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He W, Loganathan N, Tran A, Belsham DD. Npy transcription is regulated by noncanonical STAT3 signaling in hypothalamic neurons: Implication with lipotoxicity and obesity. Mol Cell Endocrinol 2024; 586:112179. [PMID: 38387703 DOI: 10.1016/j.mce.2024.112179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/27/2024] [Accepted: 02/05/2024] [Indexed: 02/24/2024]
Abstract
Neuropeptide Y (Npy) is an abundant neuropeptide expressed in the central and peripheral nervous systems. NPY-secreting neurons in the hypothalamic arcuate nucleus regulate energy homeostasis, and Npy mRNA expression is regulated by peripheral nutrient and hormonal signals like leptin, interleukin-6 (IL-6), and fatty acids. This study demonstrates that IL-6, which phosphorylates tyrosine 705 (Y705) of STAT3, decreased Npy mRNA in arcuate immortalized hypothalamic neurons. In parallel, inhibitors of STAT3-Y705 phosphorylation, stattic and cucurbitacin I, robustly upregulated Npy mRNA. Chromatin-immunoprecipitation showed high baseline total STAT3 binding to multiple regulatory regions of the Npy gene, which are decreased by IL-6 exposure. The STAT3-Npy interaction was further examined in obesity-related pathologies. Notably, in four different hypothalamic neuronal models where palmitate potently stimulated Npy mRNA, Socs3, a specific STAT3 activity marker, was downregulated and was negatively correlated with Npy mRNA levels (R2 = 0.40, p < 0.001), suggesting that disrupted STAT3 signaling is involved in lipotoxicity-mediated dysregulation of Npy. Finally, human NPY SNPs that map to human obesity or body mass index were investigated for potential STAT3 binding sites. Although none of the SNPs were linked to direct STAT3 binding, analysis show that rs17149106 (-602 G > T) is located on an upstream enhancer element of NPY, where the variant is predicted to disrupt validated binding of KLF4, a known inhibitory cofactor of STAT3 and downstream effector of leptin signaling. Collectively, this study demonstrates that STAT3 signaling negatively regulates Npy transcription, and that disruption of this interaction may contribute to metabolic disorders.
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Affiliation(s)
- Wenyuan He
- Departments of Physiology, University of Toronto, Ontario, Canada
| | | | - Andy Tran
- Departments of Physiology, University of Toronto, Ontario, Canada
| | - Denise D Belsham
- Departments of Physiology, University of Toronto, Ontario, Canada; Departments of Medicine, University of Toronto, Ontario, Canada.
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Tang W, Wu S, Tang Y, Ma J, Ao Y, Liu L, Wei K. Microarray analysis identifies lncFirre as a potential regulator of obesity-related acute lung injury. Life Sci 2024; 340:122459. [PMID: 38307237 DOI: 10.1016/j.lfs.2024.122459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/21/2024] [Accepted: 01/22/2024] [Indexed: 02/04/2024]
Abstract
AIMS The inflammatory response in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is heightened in obesity. The aim of this study was to investigate whether lncRNAs are involved in the effects of obesity on acute lung injury and to find possible effector lncRNAs. MAIN METHODS Microarray analysis was used to assess the transcriptional profiles of lncRNAs and mRNAs in lung tissues from normal (CON), high-fat diet induced obese (DIO), and obese ALI mice (DIO-ALI). GO and KEGG analyses were employed to explore the biological functions of differentially expressed genes. A lncRNA-mRNA co-expression network was constructed to identify specific lncRNA. Lung tissues and peripheral blood samples from patients with obesity and healthy lean donors were utilized to confirm the expression characteristics of lncFirre through qRT-PCR. lncFirre was knocked down in MH-S macrophages to explore its function. ELISA and Griess reagent kit were used to detect PGE2 and NO. Flow cytometry was used to detect macrophages polarization. KEY FINDINGS There were 475 lncRNAs and 404 mRNAs differentially expressed between DIO and CON, while 1348 lncRNAs and 1349 mRNAs between DIO-ALI and DIO. Obesity increased lncFirre expression in both mice and patients, and PA elevated lncFirre in MH-S. PA exacerbated the inflammation and proinflammatory polarization of MH-S induced by LPS. LncFirre knockdown inhibited the secretion of PGE2 and NO, M1 differentiation while promoted the M2 differentiation in PA and LPS co-challenged MH-S. SIGNIFICANCE Interfering with lncFirre effectively inhibit inflammation in MH-S, lncFirre can serve as a promising target for treating obesity-related ALI.
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Affiliation(s)
- Wenjing Tang
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Siqi Wu
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Yin Tang
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Jingyue Ma
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Yichan Ao
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Ling Liu
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
| | - Ke Wei
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
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Taheripak G, Sabeti N, Najar N, Razavi Z, Saharkhiz S, Alipourfard I. SIRT1 activation attenuates palmitate induced apoptosis in C 2C 12 muscle cells. Mol Biol Rep 2024; 51:354. [PMID: 38400872 DOI: 10.1007/s11033-024-09250-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/12/2024] [Indexed: 02/26/2024]
Abstract
BACKGROUND Type 2 diabetes is characterized by insulin resistance, which manifests mainly in skeletal muscles. SIRT1 has been found to play a role in the insulin signaling pathway. However, the molecular underpinnings of SIRT1's function in palmitate fatty acid-induced apoptosis still need to be better understood. METHODS In this research, skeletal muscle cells are treated with palmitate to be insulin resistant. It is approached that SIRT1 is downregulated in C2C12 muscle cells during palmitate-induced apoptosis and that activating SIRT1 mitigates this effect. RESULTS Based on these findings, palmitate-induced apoptosis suppressed mitochondrial biogenesis by lowering PGC-1 expression, while SIRT1 overexpression boosted. The SIRT1 inhibitor sirtinol, on the other hand, decreased mitochondrial biogenesis under the same conditions. This research also shows that ROS levels rise in the conditions necessary for apoptosis induction by palmitate, and ROS inhibitors can mitigate this effect. This work demonstrated that lowering ROS levels by boosting SIRT1 expression inhibited apoptotic induction in skeletal muscle cells. CONCLUSION This study's findings suggested that SIRT1 can improve insulin resistance in type 2 diabetes by slowing the rate of lipo-apoptosis and boosting mitochondrial biogenesis, among other benefits.
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Affiliation(s)
- Gholamreza Taheripak
- Department of Biochemistry, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Niusha Sabeti
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Naba Najar
- Department of Biochemistry, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zahrasadat Razavi
- Department of Biochemistry, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Saber Saharkhiz
- Division of Neuroscience, Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Iraj Alipourfard
- Institute of Physical Chemistry, Polish Academy of Sciences, Marcina Kasprzaka 44/52, Warsaw, 01-224, Poland.
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Sood A, Fernandes V, Preeti K, Rajan S, Khatri DK, Singh SB. S1PR2 inhibition mitigates cognitive deficit in diabetic mice by modulating microglial activation via Akt-p53-TIGAR pathway. Int Immunopharmacol 2024; 126:111278. [PMID: 38011768 DOI: 10.1016/j.intimp.2023.111278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/07/2023] [Accepted: 11/20/2023] [Indexed: 11/29/2023]
Abstract
Cognitive deficit is one of the challenging complications of type 2 diabetes. Sphingosine 1- phosphate receptors (S1PRs) have been implicated in various neurodegenerative and metabolic disorders. The association of S1PRs and cognition in type 2 diabetes remains elusive. Microglia-mediated neuronal damage could be the thread propagating cognitive deficit. The effects of S1PR2 inhibition on cognition in high-fat diet and streptozotocin-induced diabetic mice were examined in this work. We further assessed microglial activation and putative microglial polarisation routes. Cognitive function loss was observed after four months of diabetes induction in Type 2 diabetes animal model. JTE013, an S1PR2 inhibitor, was used to assess neuroprotection against cognitive decline and neuroinflammation in vitro and in vivo diabetes model. JTE013 (10 mg/kg) improved synaptic plasticity by upregulating psd95 and synaptophysin while reducing cognitive decline and neuroinflammation. It further enhanced anti-inflammatory microglia in the hippocampus and prefrontal cortex (PFC), as evidenced by increased Arg-1, CD206, and YM-1 levels and decreased iNOS, CD16, and MHCII levels. TIGAR, TP53-induced glycolysis and apoptosis regulator, might facilitate the anti-inflammatory microglial phenotype by promoting oxidative phosphorylation and decreasing apoptosis. However, since p53 is a TIGAR suppressor, inhibiting p53 could be beneficial. S1PR2 inhibition increased p-Akt and TIGAR levels and reduced the levels of p53 in the PFC and hippocampus of type 2 diabetic mice, thereby decreasing apoptosis. In vitro, palmitate was used to imitate sphingolipid dysregulation in BV2 cells, followed by conditioned media exposure to Neuro2A cells. JTE013 rescued the palmitate-induced neuronal apoptosis by promoting the anti-inflammatory microglia. In the present study, we demonstrate that the inhibition of S1PR2 improves cognitive function and skews microglia toward anti-inflammatory phenotype in type 2 diabetic mice, thereby promising to be a potential therapy for neuroinflammation.
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Affiliation(s)
- Anika Sood
- Department of Pharmacology and Toxicology, NIPER Hyderabad, Hyderabad, Telangana 500037, India
| | - Valencia Fernandes
- Department of Pharmacology and Toxicology, NIPER Hyderabad, Hyderabad, Telangana 500037, India
| | - Kumari Preeti
- Department of Pharmacology and Toxicology, NIPER Hyderabad, Hyderabad, Telangana 500037, India
| | - Shruti Rajan
- Department of Pharmacology and Toxicology, NIPER Hyderabad, Hyderabad, Telangana 500037, India
| | - Dharmendra Kumar Khatri
- Department of Pharmacology and Toxicology, NIPER Hyderabad, Hyderabad, Telangana 500037, India.
| | - Shashi Bala Singh
- Department of Pharmacology and Toxicology, NIPER Hyderabad, Hyderabad, Telangana 500037, India.
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Cheng L, Xu Y, Long Y, Yu F, Gui L, Zhang Q, Lu Y. Liraglutide attenuates palmitate-induced apoptosis via PKA/β-catenin/Bcl-2/Bax pathway in MC3T3-E1 cells. Naunyn Schmiedebergs Arch Pharmacol 2024; 397:329-341. [PMID: 37439807 DOI: 10.1007/s00210-023-02572-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 06/09/2023] [Indexed: 07/14/2023]
Abstract
Liraglutide (LRG), one agonist of glucagon-like peptide-1 receptor (GLP1R), has multiple lipid-lowering effects in type 2 diabetes mellitus, however, studies on the role of LRG in saturated fatty acid-induced bone loss are limited. Therefore, our aim was to investigate whether LRG reduces palmitate (PA)-induced apoptosis and whether the mechanism involves PKA/β-catenin/Bcl-2/Bax in osteoblastic MC3T3-E1 cells. MC3T3-E1 cells were treated with different concentrations of PA, LRG, or pretreated with Exendin 9-39 and H89, cell viability, intracellular reactive oxygen species (ROS), cAMP levels, apoptosis and the expression of protein kinase A (PKA) and phosphorylation of PKA (p-PKA), β-catenin and phosphorylation of β-catenin (Ser675)(p-β-catenin), GLP1R, cleaved-capase 3, Bcl2-Associated X Protein (Bax) and B-cell lymphoma-2 (Bcl-2) along with expression of Osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) were evaluated. PA treatment inhibited cell proliferation and cAMP levels, elevated intracellular ROS levels and promoted apoptosis, increased protein expressions of RANKL, Bax and cleaved-caspase3, meanwhile decreased protein expression of OPG and Bcl-2 in a dose-dependent manner. LRG inverted PA-induced apoptosis, increased cAMP levels, promoted expression of p-PKA, p-β-catenin (Ser675) and reversed these gene expressions via increasing GLP1R expression. Pretreatment of the cells with Exendin 9-39 and H89 partially eradicated the protective effect of LRG on PA-induced apoptosis and gene expressions. Therefore, these findings indicated that LRG attenuates PA-induced apoptosis possibly by GLP1R-mediated PKA/β-catenin/Bcl-2/Bax pathway in MC3T3-E1 cells. Our results point to LRG as a new strategy to attenuate bone loss associated with high fat diet beyond its lipid-lowering actions. LRG inhibits PA-mediated apoptosis via GLP1R-mediated PKA/β-catenin/Bcl-2/ Bax pathway, while possibly enhances PA-inhibited differentiation by regulating the expression of OPG and RANKL.
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Affiliation(s)
- Lanlan Cheng
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Yijing Xu
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Yueming Long
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Fangmei Yu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Li Gui
- The Comprehensive Laboratory, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Qiu Zhang
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Anhui Medical University, Hefei, China.
| | - Yunxia Lu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Anhui Medical University, Hefei, China.
- The Comprehensive Laboratory, School of Basic Medical Science, Anhui Medical University, Hefei, China.
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de Freitas-Marchi BL, Dos Santos JF, Reigado GR, Fernandes MTP, Alcalde FSC, de Oliveira Carvalho CR, Nunes VA. Effect of Uncaria tomentosa aqueous extract on the response to palmitate-induced lipotoxicity in cultured skeletal muscle cells. BMC Complement Med Ther 2023; 23:412. [PMID: 37968654 PMCID: PMC10647034 DOI: 10.1186/s12906-023-04204-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 10/06/2023] [Indexed: 11/17/2023] Open
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) is frequently associated with dyslipidemia, which corresponds to the increase in the triglycerides and fatty acid concentrations in tissues, such as the skeletal muscle. Also, T2DM molecular mechanism involves increasing in reactive oxygen species (ROS) production and oxidative stress. The use of herbal medicines such as Uncaria tomentosa (Ut) has been proposed as an auxiliary treatment for patients with T2DM. In this study, it was evaluated the effect of Ut aqueous extract on cell viability and ROS production, in skeletal myoblasts from C2C12 lineage exposed to the free fatty acid palmitate (PA). METHODS Cells were incubated with PA in different concentrations ranging from 10 to 1000 μM, for 24 or 48 h, for cytotoxicity assay. Cell death, DNA fragmentation and ROS production assays were performed in cell cultures incubated with PA for 24 h, in the pre (preventive condition) or post treatment (therapeutic condition) with 250 μg/ml Ut aqueous extract, for 2 or 6 h. Cell death was evaluated by MTT method or flow cytometry. ROS generation was measured by fluorescence spectroscopy using the DCFDA probe. RESULTS Cell viability was reduced to approximately 44% after the incubation with PA for 24 h from the concentration of 500 µM. In the incubation of cells with 500 μM PA and Ut extract for 6 h, in both conditions (preventive or therapeutic), it was observed an increase of 27 and 70% in cell viability respectively, in comparison to the cultures incubated with only PA. Also, the incubation of cultures with 500 μM PA, for 24 h, increased 20-fold the ROS formation, while the treatment with Ut extract, for 6 h, both in the preventive or therapeutic conditions, promoted decrease of 21 and 55%, respectively. CONCLUSION The Ut extract was efficient in promoting cell protection against PA lipotoxicity and ROS generation, potentially preventing oxidative stress in C2C12 skeletal muscle cells. Since T2DM molecular mechanism involves oxidative stress condition and it is often associated with dyslipidemia and fatty acid accumulation in muscle tissue, these results open perspectives for the use of Ut as an auxiliary strategy for T2DM management.
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Affiliation(s)
- Bruna Leticia de Freitas-Marchi
- Laboratory of Skin Physiology and Tissue Bioengineering, School of Arts, Sciences and Humanities, University of Sao Paulo (EACH-USP), São Paulo, SP, Brazil
| | - Jeniffer Farias Dos Santos
- Laboratory of Skin Physiology and Tissue Bioengineering, School of Arts, Sciences and Humanities, University of Sao Paulo (EACH-USP), São Paulo, SP, Brazil
| | - Gustavo Roncoli Reigado
- Laboratory of Skin Physiology and Tissue Bioengineering, School of Arts, Sciences and Humanities, University of Sao Paulo (EACH-USP), São Paulo, SP, Brazil
| | - Myrian Thiago Pruschinski Fernandes
- Laboratory of Skin Physiology and Tissue Bioengineering, School of Arts, Sciences and Humanities, University of Sao Paulo (EACH-USP), São Paulo, SP, Brazil
| | - Felipe Santiago Chambergo Alcalde
- Laboratory of Skin Physiology and Tissue Bioengineering, School of Arts, Sciences and Humanities, University of Sao Paulo (EACH-USP), São Paulo, SP, Brazil
| | | | - Viviane Abreu Nunes
- Laboratory of Skin Physiology and Tissue Bioengineering, School of Arts, Sciences and Humanities, University of Sao Paulo (EACH-USP), São Paulo, SP, Brazil.
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Tokarz VL, Mylvaganam S, Klip A. Palmitate-induced insulin resistance causes actin filament stiffness and GLUT4 mis-sorting without altered Akt signalling. J Cell Sci 2023; 136:jcs261300. [PMID: 37815440 DOI: 10.1242/jcs.261300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 09/25/2023] [Indexed: 10/11/2023] Open
Abstract
Skeletal muscle insulin resistance, a major contributor to type 2 diabetes, is linked to the consumption of saturated fats. This insulin resistance arises from failure of insulin-induced translocation of glucose transporter type 4 (GLUT4; also known as SLC2A4) to the plasma membrane to facilitate glucose uptake into muscle. The mechanisms of defective GLUT4 translocation are poorly understood, limiting development of insulin-sensitizing therapies targeting muscle glucose uptake. Although many studies have identified early insulin signalling defects and suggest that they are responsible for insulin resistance, their cause-effect has been debated. Here, we find that the saturated fat palmitate (PA) causes insulin resistance owing to failure of GLUT4 translocation in skeletal muscle myoblasts and myotubes without impairing signalling to Akt2 or AS160 (also known as TBC1D4). Instead, PA altered two basal-state events: (1) the intracellular localization of GLUT4 and its sorting towards a perinuclear storage compartment, and (2) actin filament stiffness, which prevents Rac1-dependent actin remodelling. These defects were triggered by distinct mechanisms, respectively protein palmitoylation and endoplasmic reticulum (ER) stress. Our findings highlight that saturated fats elicit muscle cell-autonomous dysregulation of the basal-state machinery required for GLUT4 translocation, which 'primes' cells for insulin resistance.
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Affiliation(s)
- Victoria L Tokarz
- Department of Physiology, University of Toronto, Ontario, M5S 1A8, Canada
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada
| | - Sivakami Mylvaganam
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada
- Department of Biochemistry, University of Toronto, Ontario, M5S 1A8, Canada
| | - Amira Klip
- Department of Physiology, University of Toronto, Ontario, M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Ontario, M5S 1A8, Canada
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Sun W, Yue J, Xu T, Cui Y, Huang D, Shi H, Xiong J, Sun W, Yi Q. Xanthohumol alleviates palmitate-induced inflammation and prevents osteoarthritis progression by attenuating mitochondria dysfunction/NLRP3 inflammasome axis. Heliyon 2023; 9:e21282. [PMID: 37964828 PMCID: PMC10641167 DOI: 10.1016/j.heliyon.2023.e21282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 11/16/2023] Open
Abstract
Osteoarthritis (OA) is a prevalent chronic degenerative joint disease worldwide. Obesity has been linked to OA, and increased free fatty acid levels (e.g., palmitate) contribute to inflammatory responses and cartilage degradation. Xanthohumol (Xn), a bioactive prenylated chalcone, was shown to exhibit antioxidative, anti-inflammatory, and anti-obesity capacities in multiple diseases. However, a clear description of the preventive effects of Xn on obesity-associated OA is unavailable. This study aimed to assess the chondroprotective function of Xn on obesity-related OA. The in vitro levels of inflammatory and ECM matrix markers in human chondrocytes were assessed after the chondrocytes were treated with PA and Xn. Additionally, in vivo cartilage degeneration was assessed following oral administration of HFD and Xn. This study found that Xn treatment completely reduces the inflammation and extracellular matrix degradation caused by PA. The proposed mechanism involves AMPK signaling pathway activation by Xn, which increases mitochondrial biogenesis, attenuates mitochondrial dysfunction, and inhibits NLRP3 inflammasome and the NF-κB signaling pathway induced by PA. In summary, this study highlights that Xn could decrease inflammation reactions and the degradation of the cartilage matrix induced by PA by inhibiting the NLRP3 inflammasome and attenuating mitochondria dysfunction in human chondrocytes.
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Affiliation(s)
- Weichao Sun
- Department of Orthopedics, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, 518035, China
- The Central Laboratory, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong 518035, China
| | - Jiaji Yue
- Department of Orthopedics, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, 518035, China
| | - Tianhao Xu
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, 646000, China
- Laboratory of Anesthesia and Organ Protection, Southwest Medical University, Luzhou, Sichuan, 646099, China
| | - Yinxing Cui
- Department of Orthopedics, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, 518035, China
- Department of Physiology, School of Basic Medical Science, Southwest Medical University, Luzhou, Sichuan, 646000, China
| | - Dixi Huang
- Department of Orthopedics, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, 518035, China
- Department of Physiology, School of Basic Medical Science, Southwest Medical University, Luzhou, Sichuan, 646000, China
| | - Houyin Shi
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, China
| | - Jianyi Xiong
- Department of Orthopedics, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, 518035, China
| | - Wei Sun
- Department of Orthopedics, Shenzhen Second People's Hospital (The First Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, 518035, China
| | - Qian Yi
- Laboratory of Anesthesia and Organ Protection, Southwest Medical University, Luzhou, Sichuan, 646099, China
- Department of Physiology, School of Basic Medical Science, Southwest Medical University, Luzhou, Sichuan, 646000, China
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Tong B, Zhang Z, Li X, Liu J, Wang H, Song L, Feng J, Dai Z, Xu Y. FUNDC1 modulates mitochondrial defects and pancreatic β-cell dysfunction under lipotoxicity. Biochem Biophys Res Commun 2023; 672:54-64. [PMID: 37336125 DOI: 10.1016/j.bbrc.2023.06.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 06/02/2023] [Accepted: 06/13/2023] [Indexed: 06/21/2023]
Abstract
Insulin resistance and many metabolic disorders are causally linked to mitochondrial dysfunction or defective mitochondrial quality control. Mitophagy is a highly selective mechanism that recognizes and removes damaged mitochondria to maintain mitochondrial homeostasis. Here, we addressed the potential role of FUNDC1, a mediator of mitophagy, in pancreatic β-cell dysfunction under lipotoxicity. In pancreatic MIN6 cells, FUNDC1 deficiency aggravated palmitate-induced mitochondrial dysfunction, which led to cell death and insulin insensitivity. Interestingly, FUNDC1 overexpression prevented these cellular harms brought on by palmitate. In mice models, pancreatic-specific FUNDC1 overexpression alleviated high-fat diet (HFD)-induced insulin resistance and obesity. Mechanistically, pancreatic-specific overexpression of FUNDC1 ameliorated mitochondrial defects and endoplasmic reticulum (ER) stress upon HFD. Our research indicates that FUNDC1 plays an essential role in apoptosis and dysfunction of pancreatic β-cells via modulating lipotoxicity-induced mitochondrial defects.
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Affiliation(s)
- Beier Tong
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Zhengwei Zhang
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Xuefeng Li
- Department of Endocrinology, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, China
| | - Jie Liu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Huawei Wang
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Linyang Song
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Jieyuan Feng
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Zhe Dai
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
| | - Yancheng Xu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
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Nag S, Mandal S, Majumdar T, Mukhopadhyay S, Kundu R. FFA-Fetuin-A regulates DPP-IV expression in pancreatic beta cells through TLR4-NFkB pathway. Biochem Biophys Res Commun 2023; 647:55-61. [PMID: 36716646 DOI: 10.1016/j.bbrc.2023.01.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 01/17/2023] [Accepted: 01/21/2023] [Indexed: 01/24/2023]
Abstract
Dipeptidyl peptidase 4 (DPP-IV) is a ubiquitous proteolytic enzyme that cleaves incretin hormones, such as glucagon-like peptide 1 (GLP1) and gastric inhibitory protein (GIP), leading to reduced glucose stimulated insulin secretion from the pancreatic beta cells. The functionally active enzyme is present in a membrane bound form in several cell types as well as in a soluble form in the circulation. The present report deals with DPP-IV expression and its regulation in the pancreatic beta cells in presence of free fatty acids (FFAs) and Fetuin-A, a circulatory glycoprotein associated with insulin resistance in humans and animals. FFA and Fetuin-A individually or in combination trigger DPP-IV expression in MIN6 cells. Islets isolated from high fat diet fed (HFD) mice (16 weeks) showed higher levels of DPP-IV expression than standard diet (SD) fed mice. Fetuin-A increased DPP-IV expression in HFD mice (4 weeks). Inhibition of TLR4 or NFkB prevented palmitate-Fetuin-A mediated DPP-IV expression in MIN6. It has been seen that Fetuin-A alone also could trigger DPP-IV expression in MIN6 cells via NFkB. Additionally, palmitate treatment exhibited reduced level of soluble DPP-IV in the media of MIN6 culture, which corroborated with the expression pattern of its protease, KLK5 that cleaves and releases the membrane bound DPP-IV into the secretion. Our results demonstrate that FFA-Fetuin-A upregulates DPP-IV expression in the pancreatic beta cells through the TLR4-NFkB pathway.
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Affiliation(s)
- Snehasish Nag
- Cell Signaling Laboratory, Department of Zoology, Visva-Bharati University, Santiniketan, 731235, India
| | - Samanwita Mandal
- Cell Signaling Laboratory, Department of Zoology, Visva-Bharati University, Santiniketan, 731235, India
| | - Tanmay Majumdar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Satinath Mukhopadhyay
- Department of Endocrinology & Metabolism, Institute of Post-Graduate Medical Education & Research-Seth Sukhlal Karnani Memorial Hospital (IPGME&R-SSKM), Kolkata, 700020, India
| | - Rakesh Kundu
- Cell Signaling Laboratory, Department of Zoology, Visva-Bharati University, Santiniketan, 731235, India.
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11
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Sood A, Fernandes V, Preeti K, Khot M, Khatri DK, Singh SB. Fingolimod Alleviates Cognitive Deficit in Type 2 Diabetes by Promoting Microglial M2 Polarization via the pSTAT3-jmjd3 Axis. Mol Neurobiol 2023; 60:901-922. [PMID: 36385233 DOI: 10.1007/s12035-022-03120-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 11/03/2022] [Indexed: 11/17/2022]
Abstract
Sphingosine receptors (S1PRs) are implicated in the progression of neurodegenerative diseases and metabolic disorders like obesity and type 2 diabetes (T2D). The link between S1PRs and cognition in type 2 diabetes, as well as the mechanisms that underpin it, are yet unknown. Neuroinflammation is the common pathology shared among T2D and cognitive impairment. However, the interplay between the M1 and M2 polarization state of microglia, a primary driver of neuroinflammation, could be the driving factor for impaired learning and memory in diabetes. In the present study, we investigated the effects of fingolimod (S1PR1 modulator) on cognition in high-fat diet and streptozotocin-induced diabetic mice. We further assessed the potential pathways linking microglial polarization and cognition in T2D. Fingolimod (0.5 mg/kg and 1 mg/kg) improved M2 polarization and synaptic plasticity while ameliorating cognitive decline and neuroinflammation. Sphingolipid dysregulation was mimicked in vitro using palmitate in BV2 cells, followed by conditioned media exposure to Neuro2A cells. Mechanistically, type 2 diabetes induced microglial activation, priming microglia towards the M1 phenotype. In the hippocampus and cortex of type 2 diabetic mice, there was a substantial drop in pSTAT3, which was reversed by fingolimod. This protective effect of fingolimod on microglial M2 polarization was primarily suppressed by selective jmjd3 blockade in vitro using GSK-J4, revealing that jmjd3 was involved downstream of STAT3 in the fingolimod-enabled shift of microglia from M1 to M2 polarization state. This study suggested that fingolimod might effectively improve cognition in type 2 diabetes by promoting M2 polarization.
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Affiliation(s)
- Anika Sood
- Molecular & Cellular Neuroscience Lab, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Hyderabad, Telangana, 500037, Hyderabad, India
| | - Valencia Fernandes
- Molecular & Cellular Neuroscience Lab, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Hyderabad, Telangana, 500037, Hyderabad, India
| | - Kumari Preeti
- Molecular & Cellular Neuroscience Lab, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Hyderabad, Telangana, 500037, Hyderabad, India
| | - Mayuri Khot
- Molecular & Cellular Neuroscience Lab, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Hyderabad, Telangana, 500037, Hyderabad, India
| | - Dharmendra Kumar Khatri
- Molecular & Cellular Neuroscience Lab, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Hyderabad, Telangana, 500037, Hyderabad, India.
| | - Shashi Bala Singh
- Molecular & Cellular Neuroscience Lab, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Hyderabad, Telangana, 500037, Hyderabad, India.
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12
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Guo Q, Zhang B, Du H, Zhu R, Sun X, Fan X, Wei X, Yang D, Oh Y, Fan L, Wang C, Gu N. High-fat diet and palmitate inhibits FNDC5 expression via AMPK-Zfp57 pathway in mouse muscle cells. Chem Biol Interact 2023; 369:110265. [PMID: 36375515 DOI: 10.1016/j.cbi.2022.110265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 11/03/2022] [Accepted: 11/11/2022] [Indexed: 11/13/2022]
Abstract
Irisin, a muscle-secreted cytokine involved in maintaining glucose homeostasis and improving insulin resistance, is generated from the precursor fibronectin type Ⅲ domain-containing protein 5 (FNDC5) by specific proteases. Zinc-finger protein Zfp57, a transcription factor that maintains the methylation during early embryonic development, is also reported to be associated with diabetes mellitus. However, the association between Zfp57 and FNDC5 is still unclear. In our study, we explored the detailed regulatory effect of Zfp57 on FNDC5 expression. In this study, we found that high-fat diet or saturated fatty acid palmitate increased the Zfp57 expression and decreased FNDC5 expression in muscle tissue or C2C12 myotubes. RNA sequencing analysis disclosed effects of the high-fat diet on genes associated with insulin resistance and the AMP-activated protein kinase (AMPK) signaling pathway in muscle tissue of mice. Chromatin immunoprecipitation experiments revealed that Zfp57 binds the FNDC5 gene promoter at positions -308 to -188. Moreover, Zfp57 overexpression inhibited FNDC5 expression, and Zfp57 knockdown alleviated the inhibitory effect of palmitate on FNDC5 expression in C2C12 myotubes. In addition, in vivo and in vitro studies demonstrated that activation of the AMPK pathway by 5-Aminoimidazole-4-carboxamide riboside (AICAR) or metformin mitigated the inhibitory effect of Zfp57 on FNDC5 expression and improved insulin resistance. These findings collectively suggest that high-fat diet and palmitate inhibit the AMPK pathway to increase Zfp57 expression, which in turn induces FNDC5 inhibition, to further aggravate insulin resistance.
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Affiliation(s)
- Qian Guo
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China; Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, Philadelphia, USA
| | - Boya Zhang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Haining Du
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Ruijiao Zhu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Xiaotong Sun
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Xingpei Fan
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Xiangjuan Wei
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - DaQian Yang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yuri Oh
- Faculty of Education, Wakayama University, Wakayama, Japan
| | - Lei Fan
- Department of Endocrinology, Heilongjiang Provincial Hospital, Harbin, Heilongjiang, China
| | - Changlin Wang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
| | - Ning Gu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China.
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13
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Dionne G, Calder M, Betts DH, Rafea BA, Watson AJ. Expression and localization of NRF2/Keap1 signalling pathway genes in mouse preimplantation embryos exposed to free fatty acids. Gene Expr Patterns 2022; 46:119281. [PMID: 36243294 DOI: 10.1016/j.gep.2022.119281] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 09/06/2022] [Accepted: 10/07/2022] [Indexed: 11/04/2022]
Abstract
Obese women experience greater incidence of infertility, with reproductive tracts exposing preimplantation embryos to elevated free fatty acids (FFA) such as palmitic acid (PA) and oleic acid (OA). PA treatment impairs mouse preimplantation development in vitro, while OA co-treatment rescues blastocyst development of PA treated embryos. In the present study, we investigated the effects of PA and OA treatment on NRF2/Keap1 localization, and relative antioxidant enzyme (Glutathione peroxidase; Gpx1, Catalase; Cat, Superoxide dismutase; Sod1 and γ-Glutamylcysteine ligase catalytic unit; Gclc) mRNA levels, during in vitro mouse preimplantation embryo development. Female mice were superovulated, mated, and embryos cultured in the presence of bovine Serum albumin (BSA) control or PA, or OA, alone (each at 100 μM) or PA + OA combined (each at 100 μM) treatment. NRF2 displayed nuclear localization at all developmental stages, whereas Keap1 primarily displayed cytoplasmic localization throughout control mouse preimplantation development in vitro. Relative transcript levels of Nrf2, Keap1, and downstream antioxidants significantly increased throughout control mouse preimplantation development in vitro. PA treatment significantly decreased blastocyst development and the levels of nuclear NRF2, while OA and PA + OA treatments did not. PA and OA treatments did not impact relative mRNA levels of Nrf2, Keap1, Gpx1, Cat, Sod1 or Gclc. Our outcomes demonstrate that cultured mouse embryos display nuclear NRF2, but that PA treatment reduces nuclear NRF2 and thus likely impacts NRF2/KEAP1 stress response mechanisms. Further studies should investigate whether free fatty acid effects on NRF2/KEAP1 contribute to the reduced fertility displayed by obese patients.
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Affiliation(s)
- Grace Dionne
- Department of Obstetrics and Gynaecology, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London ON, N6A 5C1, Canada; The Children's Health Research Institute - Lawson Health Research Institute, London ON, N6C 2R5, Canada
| | - Michele Calder
- Department of Obstetrics and Gynaecology, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London ON, N6A 5C1, Canada; The Children's Health Research Institute - Lawson Health Research Institute, London ON, N6C 2R5, Canada
| | - Dean H Betts
- Department of Obstetrics and Gynaecology, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London ON, N6A 5C1, Canada; The Children's Health Research Institute - Lawson Health Research Institute, London ON, N6C 2R5, Canada
| | - Basim Abu Rafea
- Department of Obstetrics and Gynaecology, Canada; The Children's Health Research Institute - Lawson Health Research Institute, London ON, N6C 2R5, Canada
| | - Andrew J Watson
- Department of Obstetrics and Gynaecology, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London ON, N6A 5C1, Canada; The Children's Health Research Institute - Lawson Health Research Institute, London ON, N6C 2R5, Canada.
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14
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Jäntti MH, Jackson SN, Kuhn J, Parkkinen I, Sree S, Hinkle JJ, Jokitalo E, Deterding LJ, Harvey BK. Palmitate and thapsigargin have contrasting effects on ER membrane lipid composition and ER proteostasis in neuronal cells. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159219. [PMID: 35981704 PMCID: PMC9452468 DOI: 10.1016/j.bbalip.2022.159219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 07/21/2022] [Accepted: 08/10/2022] [Indexed: 11/25/2022]
Abstract
The endoplasmic reticulum (ER) is an organelle that performs several key functions such as protein synthesis and folding, lipid metabolism and calcium homeostasis. When these functions are disrupted, such as upon protein misfolding, ER stress occurs. ER stress can trigger adaptive responses to restore proper functioning such as activation of the unfolded protein response (UPR). In certain cells, the free fatty acid palmitate has been shown to induce the UPR. Here, we examined the effects of palmitate on UPR gene expression in a human neuronal cell line and compared it with thapsigargin, a known depletor of ER calcium and trigger of the UPR. We used a Gaussia luciferase-based reporter to assess how palmitate treatment affects ER proteostasis and calcium homeostasis in the cells. We also investigated how ER calcium depletion by thapsigargin affects lipid membrane composition by performing mass spectrometry on subcellular fractions and compared this to palmitate. Surprisingly, palmitate treatment did not activate UPR despite prominent changes to membrane phospholipids. Conversely, thapsigargin induced a strong UPR, but did not significantly change the membrane lipid composition in subcellular fractions. In summary, our data demonstrate that changes in membrane lipid composition and disturbances in ER calcium homeostasis have a minimal influence on each other in neuronal cells. These data provide new insight into the adaptive interplay of lipid homeostasis and proteostasis in the cell.
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Affiliation(s)
- Maria H Jäntti
- Molecular Mechanisms of Cellular Stress and Inflammation, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224, USA.
| | - Shelley N Jackson
- Translational Analytical Core, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Jeffrey Kuhn
- Mass Spectrometry Research and Support Group, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, NC 27709, USA
| | - Ilmari Parkkinen
- Neuroscience Center, Helsinki Institute for Life Science, University of Helsinki, Haartmaninkatu 8, 00014 Helsinki, Finland
| | - Sreesha Sree
- Cell and Tissue Dynamics Research Programme, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Joshua J Hinkle
- Molecular Mechanisms of Cellular Stress and Inflammation, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Eija Jokitalo
- Cell and Tissue Dynamics Research Programme, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Leesa J Deterding
- Mass Spectrometry Research and Support Group, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, NC 27709, USA
| | - Brandon K Harvey
- Molecular Mechanisms of Cellular Stress and Inflammation, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224, USA.
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15
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He W, Tran A, Chen CT, Loganathan N, Bazinet RP, Belsham DD. Oleate restores altered autophagic flux to rescue palmitate lipotoxicity in hypothalamic neurons. Mol Cell Endocrinol 2022; 557:111753. [PMID: 35981630 DOI: 10.1016/j.mce.2022.111753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 07/29/2022] [Accepted: 08/10/2022] [Indexed: 01/18/2023]
Abstract
Accumulation of excess lipids in non-adipose tissues, such as the hypothalamus, is termed lipotoxicity and causative of free fatty acid-mediated pathology in metabolic disease. This study aimed to elucidate the molecular mechanisms behind oleate (OA)- and palmitate (PA)-mediated changes in hypothalamic neurons. Using the well-characterized hypothalamic neuronal cell model, mHypoE-46, we assessed gene changes through qRT-PCR, cell death with quantitative imaging, PA metabolism using stable isotope labeling, and cellular mechanisms using pharmacological modulation of lipid metabolism and autophagic flux. Palmitate (PA) disrupts gene expression, including Npy, Grp78, and Il-6 mRNA in mHypoE-46 hypothalamic neurons. Blocking PA metabolism using triacsin-C prevented the increase of these genes, implying that these changes depend on PA intracellular metabolism. Co-incubation with oleate (OA) is also potently protective and prevents cell death induced by increasing concentrations of PA. However, OA does not decrease U-13C-PA incorporation into diacylglycerol and phospholipids. Remarkably, OA can reverse PA toxicity even after significant PA metabolism and cellular impairment. OA can restore PA-mediated impairment of autophagy to prevent or reverse the accumulation of PA metabolites through lysosomal degradation, and not through other reported mechanisms. The autophagic flux inhibitor chloroquine (CQ) mimics PA toxicity by upregulating autophagy-related genes, Npy, Grp78, and Il-6, an effect partially reversed by OA. CQ also prevented the OA defense against PA toxicity, whereas the autophagy inducer rapamycin provided some protection. Thus, PA impairment of autophagic flux significantly contributes to its lipotoxicity, and OA-mediated protection requires functional autophagy. Overall, our results suggest that impairment of autophagy contributes to hypothalamic lipotoxicity.
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Affiliation(s)
- Wenyuan He
- Department of Physiology, University of Toronto, Ontario, Canada
| | - Andy Tran
- Department of Physiology, University of Toronto, Ontario, Canada
| | - Chuck T Chen
- Department of Nutritional Sciences, University of Toronto, Ontario, Canada
| | | | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Ontario, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Ontario, Canada; Department of Obstetrics and Gynaecology, University of Toronto, Ontario, Canada.
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16
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Kong A, Xu D, Hao T, Liu Q, Zhan R, Mai K, Ai Q. Role of acyl-coenzyme A oxidase 1 (ACOX1) on palmitate-induced inflammation and ROS production of macrophages in large yellow croaker (Larimichthys crocea). Dev Comp Immunol 2022; 136:104501. [PMID: 35961593 DOI: 10.1016/j.dci.2022.104501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/28/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
Acyl-coenzyme A oxidase 1 (ACOX1) is the rate-limiting enzyme in peroxisomal β-oxidation, and it plays an essential role in mediating the inflammatory response and reactive oxygen species (ROS) metabolism in mammals. However, the role of ACOX1 in fish has not been completely elucidated. Herein, this study was conducted to investigate the role of large yellow croaker (Larimichthys crocea) ACOX1 (Lc-ACOX1) on palmitate (PA)-induced inflammation and ROS production. In this study, Lc-ACOX1 was cloned and characterized. The full-length CDS of Lc-acox1 was 1986 bp, encoding 661 amino acids. Tissue distribution results showed that the gene expression of Lc-acox1 was the highest in the intestine and the lowest in the spleen. Moreover, results showed that the mRNA expression of Lc-acox1 was upregulated by PA, with elevated pro-inflammatory gene expression, including il-1β, il-6, il-8, tnf-α, cox2 and ifn-γ, as well as ROS content in macrophages of large yellow croaker. Furthermore, the role of Lc-ACOX1 in inflammation induced by PA was investigated by using the ACOX1 inhibitor TDYA. Treatment of macrophages with TDYA reduced the mRNA expression of pro-inflammatory genes induced by PA. Moreover, inhibition of ACOX1 reduced the elevated level of ROS caused by PA and increased the mRNA expression of antioxidant genes. In conclusion, this study first identified that fish ACOX1 was involved in the PA-induced inflammatory response and ROS production.
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Affiliation(s)
- Adong Kong
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Dan Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Tingting Hao
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Qiangde Liu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Rui Zhan
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266237, Qingdao, Shandong, PR China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266237, Qingdao, Shandong, PR China.
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17
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Zhang B, Zhu R, Sun X, Guo Q, Zhang Y, Zhang N, Oh Y, Fan L, Wang C, Gu N. Fatty acid palmitate suppresses FoxO1 expression via PERK and IRE1 unfolded protein response in C2C12 myotubes. Toxicol In Vitro 2022; 85:105459. [PMID: 36030031 DOI: 10.1016/j.tiv.2022.105459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/01/2022] [Accepted: 08/17/2022] [Indexed: 11/15/2022]
Abstract
Forkhead Box O1 (FoxO1) is a transcription factor with a unique fork head domain that indirectly participates in a variety of physiological processes and plays an important role in type 2 diabetes. Palmitate as the most abundant free fatty acid, accounting for 28-32% of total free fatty acids in human plasma. There is a direct relationship between palmitate and insulin resistance-induced type 2 diabetes. In addition, palmitate can activate the unfolded protein response signaling pathway induced by endoplasmic reticulum (ER) stress. This study aimed to investigate the response of FoxO1 to palmitate and the relationship with ER stress in C2C12 myotubes. Treatment of palmitate or tunicamycin promoted ER stress-related genes expression but suppressed FoxO1 expression, while 4-phenylbutyrate presented the opposite activity in palmitate-pretreated C2C12 myotubes, indicating that ER stress might be closely associated with FoxO1 expression. Moreover, palmitate-suppressed FoxO1 expression was reversed in C2C12 cells when the PERK and IRE-1 signaling pathway was inhibited by treatment with GSK2656157 or 4μ8C. However, no differences were observed when the ATF6 signaling pathway was suppressed by knockout of the ATF6 gene. These findings suggest that palmitate suppressed FoxO1 expression via the PERK and IRE1 signaling pathways.
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Affiliation(s)
- Boya Zhang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Ruijiao Zhu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Xiaotong Sun
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Qian Guo
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China; Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, Philadelphia, USA
| | - Yao Zhang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Nanxi Zhang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yuri Oh
- Faculty of Education, Wakayama University, Wakayama, Japan
| | - Lei Fan
- Department of Endocrinology, Heilongjiang Provincial Hospital, Harbin, Heilongjiang, China.
| | - Changlin Wang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
| | - Ning Gu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
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18
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Ding Y, Cui K, Han S, Hao T, Liu Y, Lai W, Xu X, Mai K, Ai Q. Lysophosphatidylcholine acyltransferase 3 (LPCAT3) mediates palmitate-induced inflammation in macrophages of large yellow croaker (Larimichthys crocea). Fish Shellfish Immunol 2022; 126:12-20. [PMID: 35526799 DOI: 10.1016/j.fsi.2022.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 06/14/2023]
Abstract
LPCAT3, a subtype of lysophosphatidylcholine acyltransferases, is a key enzyme in phosphatidylcholine remodeling pathway and plays a significant role in mediating inflammatory response in mammals. However, its inflammatory function in fish has yet to be discovered. Herein, this study aimed to investigate its role in inflammation in Larimichthys crocea. We analyzed the coding sequence of Larimichthys crocea LPCAT3 (Lc-LPCAT3) and explored the effect of Lc-LPCAT3 on palmitate (PA)-induced inflammation. We found that in macrophage cell line of Larimichthys crocea, the mRNA expression of Lc-lpcat3 was upregulated by PA with the elevated pro-inflammatory genes expression, including il1β, il6, il8, tnfα and ifnγ. Next, the role of Lc-LPCAT3 in inflammation induced by PA was further investigated. Results showed that knockdown of Lc-LPCAT3 mitigated PA-induced pro-inflammatory genes mRNA expression, including il1β, il8, tnfα and ifnγ, in which JNK signaling pathway was involved. In contrast, overexpression of Lc-LPCAT3 induced pro-inflammatory genes expression including il1β, tnfα and ifnγ. Furthermore, several transcription factors with negative regulation of Lc-LPCAT3 promoter activity were discovered including LXRα, RXRα, PPARα, PPARγ, CEBPα, CEBPβ, CEBPδ, SREBP1 and SREBP2, and SREBP1 had the strongest regulatory effect. In conclusion, we first discovered that fish LPCAT3 participated in PA-induced inflammation, and targeting SREBP1 might be an effective coping strategy.
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Affiliation(s)
- Yi Ding
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Kun Cui
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Shangzhe Han
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Tingting Hao
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Yongtao Liu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Wencong Lai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Xiang Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266003, Qingdao, Shandong, PR China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affair), Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266003, Qingdao, Shandong, PR China.
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19
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Ishaq A, Tchkonia T, Kirkland JL, Siervo M, Saretzki G. Palmitate induces DNA damage and senescence in human adipocytes in vitro that can be alleviated by oleic acid but not inorganic nitrate. Exp Gerontol 2022; 163:111798. [PMID: 35390489 PMCID: PMC9214712 DOI: 10.1016/j.exger.2022.111798] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/28/2022] [Accepted: 03/31/2022] [Indexed: 11/22/2022]
Abstract
Hypertrophy in white adipose tissue (WAT) can result in sustained systemic inflammation, hyperlipidaemia, insulin resistance, and onset of senescence in adipocytes. Inflammation and hypertrophy can be induced in vitro using palmitic acid (PA). WAT adipocytes have innately low β-oxidation capacity, while inorganic nitrate can promote a beiging phenotype, with promotion of β-oxidation when cells are exposed to nitrate during differentiation. We hypothesized that treatment of human adipocytes with PA in vitro can induce senescence, which might be attenuated by nitrate treatment through stimulation of β-oxidation to remove accumulated lipids. Differentiated subcutaneous and omental adipocytes were treated with PA and nitrate and senescence markers were analyzed. PA induced DNA damage and increased p16INK4a levels in both human subcutaneous and omental adipocytes in vitro. However, lipid accumulation and lipid droplet size increased after PA treatment only in subcutaneous adipocytes. Thus, hypertrophy and senescence seem not to be causally associated. Contrary to our expectations, subsequent treatment of PA-induced adipocytes with nitrate did not attenuate PA-induced lipid accumulation or senescence. Instead, we found a significantly beneficial effect of oleic acid (OA) on human subcutaneous adipocytes when applied together with PA, which reduced the DNA damage caused by PA treatment.
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Affiliation(s)
- Abbas Ishaq
- Biosciences Institute, Campus for Ageing and Vitality, Newcastle upon Tyne, UK
| | - Tamara Tchkonia
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, United States of America
| | - James L Kirkland
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, United States of America
| | - Mario Siervo
- Human Nutrition Research Centre, Population Health Sciences Institute, Newcastle University, Newcastle upon Tyne, UK; School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - Gabriele Saretzki
- Biosciences Institute, Campus for Ageing and Vitality, Newcastle upon Tyne, UK.
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20
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Yuan Y, Zhou C, Guo X, Ding Y, Ma S, Gong X, Jiang H, Wang Y, Wang X. Palmitate impairs the autophagic flux to induce p62-dependent apoptosis through the upregulation of CYLD in NRCMs. Toxicology 2022; 465:153032. [PMID: 34774660 DOI: 10.1016/j.tox.2021.153032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 01/01/2023]
Abstract
The most abundant saturated free fatty acid such as palmitate (PA), can accumulate in cardiomyocytes and induce lipotoxicity. CYLD is a known regulator in the development of cardiovascular disease and an important mediator of apoptosis. The role of CYLD in PA-induced cardiomyocyte apoptosis is not completely known. Here, we showed that PA treatment resulted in a concentration- and time-dependent effect on neonatal rat cardiomyocytes (NRCMs) apoptosis. PA impaired autophagy by significantly increasing the expression levels of LC3-II, Beclin 1, and also p62 in NRCMs. The autophagy flux was measured by detecting the fluorescence in the cells with Ad-mCherry-GFP-LC3B, a decrease in red puncta and a significant increase in yellow puncta in response to PA stimulation indicated that PA impairs the autophagic flux at the late stage of autophagosome-lysosome fusion. We further found knocked down of p62 by siRNA significantly decreased the expression level of cleaved caspase-3, decreased the apoptosis rate, also alleviated the loss of mitochondrial membrane potential, and decreased AIF and Cyt C releasing from mitochondria into the cytoplasm in the PA-treated NRCMs. From this, we considered that p62 accumulation was responsible for mitochondria-mediated apoptosis in PA-treated NRCMs. In addition, PA-induced a strong elevation of CYLD, siRNA-mediated knockdown of CYLD significantly antagonized PA-induced apoptosis and restored the autophagic flux in NRCMs. Knockdown of CYLD activation of the Wnt/β-catenin pathway to restore the autophagic flux and reduce the accumulation of p62 in PA- stimulated NRCMs, while an inhibitor of the Wnt/β-catenin pathway reversed this effect. Thus, our findings provide new insight into the molecular mechanism of PA toxicity in myocardial cells and suggest that CYLD may be a new therapeutic target for lipotoxic cardiomyopathy.
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Affiliation(s)
- Yahong Yuan
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China; Hubei Clinical Research Center for Precise Diagnosis and Treatment of Liver Cancer, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Chunfang Zhou
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Xingrong Guo
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Yan Ding
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Shinan Ma
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Xuewen Gong
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Hongkuan Jiang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Yunfen Wang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Xiaoli Wang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China; Hubei Clinical Research Center for Precise Diagnosis and Treatment of Liver Cancer, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
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21
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Xu YN, Wang Z, Zhang SK, Xu JR, Pan ZX, Wei X, Wen HH, Luo YS, Guo MJ, Zhu Q. Low-grade elevation of palmitate and lipopolysaccharide synergistically induced β-cell damage via inhibition of neutral ceramidase. Mol Cell Endocrinol 2022; 539:111473. [PMID: 34610358 DOI: 10.1016/j.mce.2021.111473] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/28/2021] [Accepted: 09/30/2021] [Indexed: 02/08/2023]
Abstract
High concentrations of free fatty acids (FFAs) or lipopolysaccharide (LPS) could lead to β-cell apoptosis and dysfunction, while low-grade elevation of FFAs or LPS, which are more common in people with type 2 diabetes mellitus (T2DM) or obesity, have no obvious toxic effect on β-cells. Palmitate is a component closely related to metabolic disorders in FFAs. Recent studies have found that low-grade elevation of palmitate and LPS synergistically affects the sphingolipid signaling pathway by activating Toll-like receptor 4 (TLR4) and further enhances the expression of inflammatory cytokines in immune cells. Previous studies demonstrated that sphingolipids also played an important role in the occurrence and development of T2DM. This study aimed to investigate the synergistic effects of low-grade elevation of palmitate and LPS on viability, apoptosis and insulin secretion in the rat pancreatic β-cell line INS-1 or islets and the role of sphingolipids in this process. We showed that low-grade elevation of palmitate or LPS alone did not affect the viability, apoptosis, glucose-stimulated insulin secretion (GSIS) or intracellular insulin content of INS-1 cells or islets, while the combination of the two synergistically inhibited cell viability, induced apoptosis and decreased basal insulin secretion in INS-1 cells or islets. Treatment with palmitate and LPS markedly upregulated TLR4 protein expression and downregulated neutral ceramidase (NCDase) activity and protein expression. Additionally, low-grade elevation of palmitate and LPS synergistically induced a significant increase in ceramide and a decrease in sphingosine-1-phosphate. Blocking TLR4 signaling or overexpressing NCDase remarkably attenuated INS-1 cell injury induced by the combination of palmitate and LPS. However, inhibition of ceramide synthase did not ameliorate injury induced by palmitate and LPS. Overall, we show for the first time that low-grade elevation of palmitate and LPS synergistically induced β-cell damage by activating TLR4 signaling, inhibiting NCDase activity, and further modulating sphingolipid metabolism, which was different from a high concentration of palmitate-induced β-cell injury by promoting ceramide synthesis.
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Affiliation(s)
- Ya-Nan Xu
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China
| | - Zheng Wang
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China; Department of Nephrology, Jiangsu University Affiliated People's Hospital, Zhenjiang, 212002, China
| | - Shao-Kun Zhang
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China
| | - Jia-Rong Xu
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China
| | - Zhi-Xiong Pan
- Guangxi Health Commission Key Laboratory of Basic Research in Sphingolipid Metabolism Related Diseases, Affiliated Hospital of Guilin Medical University, Guilin, 541001, China
| | - Xiao Wei
- Department of Endocrinology, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, China
| | - Hong-Hua Wen
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China
| | - Yan-Shi Luo
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China
| | - Mao-Jun Guo
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China
| | - Qun Zhu
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, China.
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22
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Wang SY, Zou C, Liu XF, Yan YJ, Gu SZ, Li X. Vascular endothelial growth factor ameliorated palmitate-induced cardiomyocyte injury via JNK pathway. In Vitro Cell Dev Biol Anim 2021; 57:886-95. [PMID: 34791626 DOI: 10.1007/s11626-021-00616-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 08/16/2021] [Indexed: 11/02/2022]
Abstract
Enhanced apoptosis of cardiomyocytes in suffering overloaded saturated fatty acids (SFAs) can result in myocardial infarction and cardiac dysfunction. The function of vascular endothelial growth factor (VEGF) in cardiomyocyte protection was not clearly described. To investigate the preservative effects of VEGF sensitization on ceramide-mediated programmed cell death of cardiomyocytes, palmitate-induced injury in H9c2 cells was established as an in vitro model. Results revealed that 0.5 mM palmitate application effectively led to debased viability and activated apoptotic factors. A significant time-dependent relation between PAL and cardiomyocyte injury was observed. The apoptosis rate was increased greatly after 16 h of treatment with 0.5 mM PAL. In addition, cell viability was restored by VEGF overexpression during treatment with 0.5 mM PAL. Reduced apoptosis rate and expression of caspase 3, Bax, and NF-κB p65 were observed in this process, while boosted Bcl-2, p-JNK/JNK expression and activity of caspase 3 were checked. However, p-ERK/ERK levels did not exhibit a significant change. These findings indicated the protective effects of VEGF in confronting the ceramide-induced cardiomyocyte apoptosis, and would devote therapeutic targets for cardiovascular safeguard in dealing with fatty acid stress.
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23
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Loomba R, Mohseni R, Lucas KJ, Gutierrez JA, Perry RG, Trotter JF, Rahimi RS, Harrison SA, Ajmera V, Wayne JD, O'Farrell M, McCulloch W, Grimmer K, Rinella M, Wai-Sun Wong V, Ratziu V, Gores GJ, Neuschwander-Tetri BA, Kemble G. TVB-2640 (FASN Inhibitor) for the Treatment of Nonalcoholic Steatohepatitis: FASCINATE-1, a Randomized, Placebo-Controlled Phase 2a Trial. Gastroenterology 2021; 161:1475-1486. [PMID: 34310978 DOI: 10.1053/j.gastro.2021.07.025] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/17/2021] [Accepted: 07/13/2021] [Indexed: 12/30/2022]
Abstract
BACKGROUND & AIMS Increased de novo lipogenesis creates excess intrahepatic fat and lipotoxins, propagating liver damage in nonalcoholic steatohepatitis. TVB-2640, a fatty acid synthase inhibitor, was designed to reduce excess liver fat and directly inhibit inflammatory and fibrogenic pathways. We assessed the safety and efficacy of TVB-2640 in patients with nonalcoholic steatohepatitis in the United States. METHODS 3V2640-CLIN-005 (FASCINATE-1) was a randomized, placebo-controlled, single-blind study at 10 US sites. Adults with ≥8% liver fat, assessed by magnetic resonance imaging proton density fat fraction, and evidence of liver fibrosis by magnetic resonance elastography ≥2.5 kPa or liver biopsy were eligible. Ninety-nine patients were randomized to receive placebo or 25 mg or 50 mg of TVB-2640 (orally, once-daily for 12 weeks). The primary end points of this study were safety and relative change in liver fat after treatment. RESULTS Liver fat increased in the placebo cohort by 4.5% relative to baseline; in contrast TVB-2640 reduced liver fat by 9.6% in the 25-mg cohort (n = 30; least squares mean: -15.5%; 95% confidence interval, -31.3 to -0.23; P = .053), and 28.1% in the 50-mg cohort (n = 28; least squares mean: -28.0%; 95% confidence interval, -44.5 to -11.6; P = .001). Eleven percent of patients in the placebo group achieved a ≥30% relative reduction of liver fat compared to 23% in the 25-mg group, and 61% in the 50-mg group (P < .001). Secondary analyses showed improvements of metabolic, pro-inflammatory and fibrotic markers. TVB-2640 was well tolerated; adverse events were mostly mild and balanced among the groups. CONCLUSIONS TVB-2640 significantly reduced liver fat and improved biochemical, inflammatory, and fibrotic biomarkers after 12 weeks, in a dose-dependent manner in patients with nonalcoholic steatohepatitis. ClinicalTrials.gov, Number NCT03938246.
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Affiliation(s)
- Rohit Loomba
- Nonalcoholic Fatty Liver Disease Research Center, Division of Gastroenterology and Hepatology, Department of Medicine, University of California at San Diego, La Jolla, California.
| | | | | | | | | | - James F Trotter
- Baylor University Medical Center, Texas Digestive Disease Consultants, Dallas, Texas
| | - Robert S Rahimi
- Baylor University Medical Center, Texas Digestive Disease Consultants, Dallas, Texas
| | | | - Veeral Ajmera
- Nonalcoholic Fatty Liver Disease Research Center, Division of Gastroenterology and Hepatology, Department of Medicine, University of California at San Diego, La Jolla, California
| | | | | | | | | | - Mary Rinella
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Vincent Wai-Sun Wong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong
| | - Vlad Ratziu
- Sorbonne Université, Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtriére, Institute for Cardiometabolism and Nutrition, Paris, France
| | - Gregory J Gores
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Brent A Neuschwander-Tetri
- Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St Louis, Missouri
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24
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Griffiths A, Wang J, Song Q, Iyamu ID, Liu L, Park J, Jiang Y, Huang R, Song Z. Nicotinamide N-methyltransferase (NNMT) upregulation via the mTORC1-ATF4 pathway activation contributes to palmitate-induced lipotoxicity in hepatocytes. Am J Physiol Cell Physiol 2021; 321:C585-C595. [PMID: 34378991 DOI: 10.1152/ajpcell.00195.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Defined as the dysfunction and/or cell death caused by toxic lipids accumulation in hepatocytes, hepatic lipotoxicity plays a pathological role in non-alcoholic fatty liver disease. The cellular and molecular mechanisms underlying lipotoxicity remain to be elucidated. In this study, using AML12 cells, a non-transformed murine hepatocyte cell line, exposed to palmitate (a 16-C saturated fatty acid) as an experimental model, we investigated the role and mechanisms of nicotinamide N-methyltransferase (NNMT), a methyltransferase catalyzing nicotinamide methylation and degradation, in hepatic lipotoxicity. We initially identified activating transcription factor 4 (ATF4) as a major transcription factor for hepatic NNMT expression. Here, we demonstrated that palmitate upregulates NNMT expression via activating ATF4 in a mechanistic target of rapamycin complex 1 (mTORC1)-dependent mechanism in that mTORC1 inhibition by both Torin1 and rapamycin attenuated ATF4 activation and NNMT upregulation. We further demonstrated that the mTORC1-dependent ATF4 activation is an integral signaling event of unfolded protein response (UPR) as both ATF4 activation and NNMT upregulation by tunicamycin, a well-documented endoplasmic reticulum (ER) stress inducer, are blunted when hepatocytes were pretreated with Torin1. Importantly, our data uncovered that NNMT upregulation contributes to palmitate-induced hepatotoxicity as NNMT inhibition, via either pharmacological (NNMT inhibitors) or genetic approach (siRNA transfection), provided protection against palmitate lipotoxicity. Our further mechanistic exploration identified protein kinase A (PKA) activation to contribute, at least, partially to the protective effect of NNMT inhibition against lipotoxicity. Collectively, our data demonstrated that NNMT upregulation by the mTORC1-ATF4 pathway activation contributes to the development of lipotoxicity in hepatocytes.
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Affiliation(s)
- Alexandra Griffiths
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, United States
| | - Jun Wang
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, United States.,Department of Gastroenterology, Tongji Medical College and The Central Hospital of Wuhan, Huazhong University of Science and Technology, Wuhan, China
| | - Qing Song
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, United States
| | - Iredia D Iyamu
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Lifeng Liu
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, United States
| | - Jooman Park
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, United States
| | - Yuwei Jiang
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, United States
| | - Rong Huang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Zhenyuan Song
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, United States
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25
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Shimell JJ, Globa A, Sepers MD, Wild AR, Matin N, Raymond LA, Bamji SX. Regulation of hippocampal excitatory synapses by the Zdhhc5 palmitoyl acyltransferase. J Cell Sci 2021; 134:237816. [PMID: 33758079 PMCID: PMC8182408 DOI: 10.1242/jcs.254276] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 03/12/2021] [Indexed: 12/17/2022] Open
Abstract
Palmitoylation is the most common post-translational lipid modification in the brain; however, the role of palmitoylation and palmitoylating enzymes in the nervous system remains elusive. One of these enzymes, Zdhhc5, has previously been shown to regulate synapse plasticity. Here, we report that Zdhhc5 is also essential for the formation of excitatory, but not inhibitory, synapses both in vitro and in vivo. We demonstrate in vitro that this is dependent on the enzymatic activity of Zdhhc5, its localization at the plasma membrane and its C-terminal domain, which has been shown to be truncated in a patient with schizophrenia. Loss of Zdhhc5 in mice results in a decrease in the density of excitatory hippocampal synapses accompanied by alterations in membrane capacitance and synaptic currents, consistent with an overall decrease in spine number and silent synapses. These findings reveal an important role for Zdhhc5 in the formation and/or maintenance of excitatory synapses. Summary: The plasma membrane-associated Zdhhc5 enzyme enhances excitatory synapse formation in vitro and in vivo through motifs at its C-terminal domain.
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Affiliation(s)
- Jordan J Shimell
- Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Andrea Globa
- Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Marja D Sepers
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Psychiatry, Kinsmen Laboratory of Neurological Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Angela R Wild
- Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Nusrat Matin
- Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Lynn A Raymond
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Psychiatry, Kinsmen Laboratory of Neurological Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Shernaz X Bamji
- Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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26
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Alipourfard I, Bakhtiyari S, Gheysarzadeh A, Di Renzo L, De Lorenzo A, Mikeladze D, Khamoushi A. The Key Role of Akt Protein Kinase in Metabolic-Inflammatory Pathways Cross-Talk: TNF-α Down-Regulation and Improving of Insulin Resistance in HepG2 Cell Line. Curr Mol Med 2021; 21:257-264. [PMID: 32338219 DOI: 10.2174/1566524020666200427102209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 04/02/2020] [Accepted: 04/12/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Elevation of plasma free fatty acids as a principal aspect of type 2 diabetes maintains etiologically insulin insensitivity in target cells. TNF-α inhibitory effects on key insulin signaling pathway elements remain to be verified in insulinresistant hepatic cells. Thus, TNF-α knockdown effects on the key elements of insulin signaling were investigated in the palmitate-induced insulin-resistant hepatocytes. The Akt serine kinase, a key protein of the insulin signaling pathway, phosphorylation was monitored to understand the TNF-α effect on probable enhancing of insulin resistance. METHODS Insulin-resistant HepG2 cells were produced using 0.5 mM palmitate treatment and shRNA-mediated TNF-α gene knockdown and its down-regulation confirmed using ELISA technique. Western blotting analysis was used to assess the Akt protein phosphorylation status. RESULTS Palmitate-induced insulin resistance caused TNF-α protein overexpression 1.2-, 2.78, and 2.25- fold as compared to the control cells at post-treatment times of 8 h, 16 h, and 24 h, respectively. In the presence of palmitate, TNF-α expression showed around 30% reduction in TNF-α knockdown cells as compared to normal cells. In the TNF-α down-regulated cell, Akt phosphorylation was approximately 62% more than control cells after treatment with 100 nM insulin in conjugation with 0.5 mM palmitate. CONCLUSIONS The obtained data demonstrated that TNF-α protein expression reduction improved insulin-stimulated Akt phosphorylation in the HepG2 cells and decreased lipidinduced insulin resistance of the diabetic hepatocytes.
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Affiliation(s)
- Iraj Alipourfard
- Institute of Chemical Biology, School of Natural Sciences and Engineering, Ilia State University, Tbilisi, Georgia
| | - Salar Bakhtiyari
- Department of Clinical Biochemistry, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran
| | - Ali Gheysarzadeh
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Laura Di Renzo
- Section of Clinical Nutrition and Nutrigenomics, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy
| | - Antonio De Lorenzo
- Section of Clinical Nutrition and Nutrigenomics, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy
| | - David Mikeladze
- Institute of Chemical Biology, School of Natural Sciences and Engineering, Ilia State University, Tbilisi, Georgia
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27
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Abstract
Palmitate is a saturated fatty acid that is well known to induce endoplasmic reticulum (ER) stress and autophagy. A high-fat diet increases the palmitate level in the hypothalamus, the main region of the brain regulating energy metabolism. Interestingly, hypothalamic palmitate level is also increased under starvation, urging the study to distinguish the effects of elevated hypothalamic palmitate level under different nutrient conditions. Herein, we show that ER-phagy (ER-targeted selective autophagy) is required for progress of ER stress and that palmitate decreases ER stress by inhibiting ER-phagy in hypothalamic cells under starvation. Palmitate inhibited starvation-induced ER-phagy by increasing the level of B-cell lymphoma 2 (Bcl-2) protein, which inhibits autophagy initiation. These findings suggest that, unlike the induction of ER stress under nutrient-rich conditions, palmitate protects hypothalamic cells from starvation-induced stress by inhibiting ER-phagy.
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Affiliation(s)
- Yun Lim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea
| | - Seolsong Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea
| | - Eun-Kyoung Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea. .,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea.
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Wang X, Chen S, He J, Chen W, Ding Y, Huang J, Huang J. Histone methyltransferases G9a mediated lipid-induced M1 macrophage polarization through negatively regulating CD36. Metabolism 2021; 114:154404. [PMID: 33069810 DOI: 10.1016/j.metabol.2020.154404] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/30/2020] [Accepted: 10/11/2020] [Indexed: 01/01/2023]
Abstract
BACKGROUND Recent studies have considered the obesity-related lipid environment as the potential cause for M1 macrophage polarization in type 2 diabetes. However, the specific regulatory mechanism is still unclear. Here, we investigated the role and molecular mechanism of histone methyltransferases G9a in lipids-induced M1 macrophage polarization in type 2 diabetes. METHODS We used saturated fatty acid palmitate to induce macrophage polarization, and performed real-time PCR, western blot, flow cytometry and CHIP assay to study the function and molecular mechanism of G9a. Additionally, we isolated the peripheral blood mononuclear cells (PBMCs) from 187 patients with type 2 diabetes and 68 healthy individuals, and analyzed the expression level of G9a. RESULTS The palmitate treatment induced the macrophage M1 polarization, and decreased the expression of G9a. The deficiency of G9a could promote the palmitate-induced M1 macrophage polarization, whereas, over-expressing G9a notably suppressed this process. Meanwhile, we observed the regulatory role of G9a on the ER stress which could contribute to M1 macrophage. Furthermore, we identified the fatty acid transport protein CD36 as the potential target of G9a. Dependent on the methyltransferase activity, G9a could negatively regulate the expression of CD36 induced by palmitate. The CD36 inhibitor SSO could significantly attenuate the regulatory effect of G9a on M1 macrophage polarization and ER stress. Importantly, G9a was decreased, and suppressed CD36 and M1 macrophage genes in the PBMCs from individuals with type 2 diabetes. CONCLUSIONS Our studies demonstrate that G9a plays critical roles in lipid-induced M1 macrophage polarization via negatively regulating CD36.
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Affiliation(s)
- Xiuling Wang
- Department of Medical Laboratory, The Central Hospital of Wuhan, Huazhong University of Science and Technology, Wuhan, China
| | - Shanshan Chen
- Key Laboratory for Molecular Diagnosis of Hubei Province, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jinrong He
- Key Laboratory for Molecular Diagnosis of Hubei Province, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Weiqun Chen
- Key Laboratory for Molecular Diagnosis of Hubei Province, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Ding
- Key Laboratory for Molecular Diagnosis of Hubei Province, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Juan Huang
- Department of Nephrology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Jin Huang
- Key Laboratory for Molecular Diagnosis of Hubei Province, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Mondal A, Burchat N, Sampath H. Palmitate exacerbates bisphenol A toxicity via induction of ER stress and mitochondrial dysfunction. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158816. [PMID: 32976987 PMCID: PMC7686068 DOI: 10.1016/j.bbalip.2020.158816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/14/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022]
Abstract
Combined exposure to dietary nutrients and environmental chemicals may elicit significantly different physiological effects than single exposures. Exposure to dietary saturated fats and environmental toxins is a physiologically-significant dual exposure that is particularly associated with lower socioeconomic status, potentially placing these individuals at heightened risk of xenobiotic toxicities. However, no prior studies have examined interactions between specific lipids and environmental xenobiotics in modulating cellular health. Using primary mouse embryonic fibroblasts, we have discovered that prior exposure to the saturated fatty acid, palmitate, exacerbates cellular toxicity associated with the industrial plasticizer, bisphenol A (BPA). Cell death upon BPA exposure following palmitate pre-treatment was greater than that occurring with either exposure alone. Mechanistically, cell death was preceded by increased endoplasmic reticulum stress and loss of mitochondrial membrane potential in palmitate plus BPA exposed cells, leading to increased caspase-3 cleavage and subsequent apoptosis. Interestingly, inclusion of the unsaturated fatty acid, oleate, along with palmitate during the pre-treatment period completely abrogated the ER stress, mitochondrial toxicity, and cell death induced by subsequent exposure to BPA. Thus, our data identify for the first time an important interaction between a fatty acid and an environmental toxin and have implications for developing nutritional interventions to mitigate the deleterious effects of such xenobiotic exposures.
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Affiliation(s)
- Anupom Mondal
- Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ, USA; Center for Nutrition, Microbiome, and Health, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, USA; Invivotek, A Genesis Biotechnology Group, Hamilton, NJ, USA
| | - Natalie Burchat
- Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ, USA; Center for Nutrition, Microbiome, and Health, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, USA
| | - Harini Sampath
- Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ, USA; Center for Nutrition, Microbiome, and Health, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, USA; Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA.
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Vilas-Boas EA, Nalbach L, Ampofo E, Lucena CF, Naudet L, Ortis F, Carpinelli AR, Morgan B, Roma LP. Transient NADPH oxidase 2-dependent H 2O 2 production drives early palmitate-induced lipotoxicity in pancreatic islets. Free Radic Biol Med 2021; 162:1-13. [PMID: 33249137 DOI: 10.1016/j.freeradbiomed.2020.11.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 01/12/2023]
Abstract
Modern lifestyles, including lack of physical activity and poor nutritional habits, are driving the rapidly increasing prevalence of obesity and type 2 diabetes. Increased levels of free fatty acids (FFAs), particularly saturated FFAs, in obese individuals have been linked to pancreatic β-cell failure. This process, termed lipotoxicity, involves activation of several stress responses, including ER stress and oxidative stress. However, the molecular underpinnings and causal relationships between the disparate stress responses remain unclear. Here we employed transgenic mice, expressing a genetically-encoded cytosolic H2O2 sensor, roGFP2-Orp1, to monitor dynamic changes in H2O2 levels in pancreatic islets in response to chronic palmitate exposure. We identified a transient increase in H2O2 levels from 4 to 8 h after palmitate addition, which was mirrored by a concomitant decrease in cellular NAD(P)H levels. Intriguingly, islets isolated from NOX2 knock-out mice displayed no H2O2 transient upon chronic palmitate treatment. Furthermore, NOX2 knockout rescued palmitate-dependent impairment of insulin secretion, calcium homeostasis and viability. Chemical inhibition of NOX activity protected islets from palmitate-induced impairment in insulin secretion, however had no detectable impact upon the induction of ER stress. In summary, our results reveal that transient NOX2-dependent H2O2 production is a likely cause of early palmitate-dependent lipotoxic effects.
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Affiliation(s)
- Eloisa Aparecida Vilas-Boas
- Department of Biophysics, Center for Human and Molecular Biology (ZHMB), Saarland University, Homburg, Germany; Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Lisa Nalbach
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Camila Ferraz Lucena
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Léa Naudet
- Department of Biophysics, Center for Human and Molecular Biology (ZHMB), Saarland University, Homburg, Germany
| | - Fernanda Ortis
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Bruce Morgan
- Institute for Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Leticia Prates Roma
- Department of Biophysics, Center for Human and Molecular Biology (ZHMB), Saarland University, Homburg, Germany.
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Wang J, Lin Z, Yang Z, Liu X. lncRNA Eif4g2 improves palmitate-induced dysfunction of mouse β-cells via modulation of Nrf2 activation. Exp Cell Res 2020; 396:112291. [PMID: 32956705 DOI: 10.1016/j.yexcr.2020.112291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 12/22/2022]
Abstract
Chronic oxidative stress resulting from hyperlipidemia is thought to be a key pathogenic driver of pancreatic β-cell dysfunction in leading to the onset of type 2 diabetes mellitus (T2DM). Long non-coding RNAs (lncRNAs) have been increasingly recognized to regulate dysfunction within pancreatic β-cells in the context of T2DM. In the present study, we sought to comprehensively analyze the roles of lncRNAs in dysfunctional β-cells and mouse islets. Analyses of INS-1E cells were performed by RNA-seq and qRT-PCR after treating with or without 0.5 mM palmitate for 4 days, leading us to identify the novel lncRNA Eif4g2 (lncEif4g2) as a functional regulator within these cells. When we overexpressed lncEif4g2 in INS-1E β-cells and mouse islets, this was sufficient for the reversal of palmitate-mediated reductions in cell viability, insulin production, ATP production by mitochondria, and creation of intracellular reactive oxygen species (ROS) and the dysfunction of mouse islets, with nuclear factor erythroid 2 related factor 2 (Nrf2) activation also being observed. In contrast, when lncEif4g2 was knocked down this led INS-1E cells and mouse islets to become more sensitive to palmitate-induced dysfunction, with reduced Nrf2 nuclear translocation also being detected. When antioxidants were used to treat INS-1E cells and mouse islets, however, these negative effects were reversed. Additional functional analyses revealed lncEif4g2 to be capable of directly binding to miR-3074-5p in β-cells, with the expression of lncEif4g2 and miR-3074-5p being negatively correlated with one another. We further found that cAMP-responsive element binding-protein (CREB) was a miR-3074-5p target gene in these cells, thus at least in part serving as a functional mediator of the lncEif4g2/miR-3074-5p axis within dysfunctional β-cells. In summary, our results thus reveal that lncEif4g2 is able to indirectly regulate the expression of CREB via targeting miR-3074-5p in INS-1E cells and mouse islets, thereby leading to enhanced Nrf2 activation.
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Affiliation(s)
- Jing Wang
- Department of Endocrinology, The 1st Affiliated Hospital of Harbin Medical University, Harbin, 150001, China.
| | - Zijing Lin
- Department of Endocrinology, The 1st Affiliated Hospital of Harbin Medical University, Harbin, 150001, China
| | - Zhuowen Yang
- Department of Gerontology, The 1st Affiliated Hospital of Harbin Medical University, Harbin, 150001, China
| | - Xiaomin Liu
- Department of Endocrinology, The 1st Affiliated Hospital of Harbin Medical University, Harbin, 150001, China
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Su Y, Chen Q, Ju Y, Li W, Li W. Palmitate induces human glomerular mesangial cells fibrosis through CD36-mediated transient receptor potential canonical channel 6/nuclear factor of activated T cell 2 activation. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158793. [PMID: 32800850 DOI: 10.1016/j.bbalip.2020.158793] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/06/2020] [Accepted: 08/09/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Our previous study suggested that palmitate (PA) induces human glomerular mesangial cells (HMCs) fibrosis. However, the mechanism is not fully understood. Recent studies suggested that transient receptor potential canonical channel 6 (TRPC6)/nuclear factor of activated T cell 2 (NFAT2) played an important role in renal fibrosis. Moreover, cluster of differentiation 36 (CD36) regulated the synthesis of TPRC6 agonist diglyceride. In the present study, we investigated whether PA induced HMCs fibrosis via TRPC6/NFAT2 mediated by CD36. METHODS A type 2 diabetic nephropathy (DN) model was established in Sprague Dawley rats, and HMCs were stimulated with PA. Lipid accumulation and free fatty acid (FFA) uptake were measured. The expression levels of TGF-β1, p-Smad2/3, FN, TRPC6, NFAT2 and CD36 were evaluated. The intracellular calcium concentration ([Ca2+]i) was assessed. RESULTS FFA were elevated in type 2 DN rats with kidney fibrosis in addition to NFAT2 and CD36 expression. In vitro, PA induced HMCs fibrosis, [Ca2+]i elevation and NFAT2 activation. SKF96365 or TRPC6-siRNA could attenuate PA-induced HMCs damage. By contrast, the TRPC6 activator showed the opposite effect. Moreover, NFAT2-siRNA also suppressed PA-induced HMCs fibrosis. CD36 knockdown inhibited the PA-induced [Ca2+]i elevation and NFAT2 expression. In addition, long-term treatment with PA decreased TRPC6 expression in HMCs. CONCLUSION The results of this study demonstrated that PA could induce the activation of the [Ca2+]i/NFAT2 signaling pathway through TRPC6, which led to HMCs fibrosis. Although activation of TRPC6 attributed to CD36-mediated lipid deposition, long-term stimulation of PA may lead to negative feedback on the expression of TPRC6.
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Affiliation(s)
- Yong Su
- Department of Pharmacy, The First Affiliated Hospital of Anhui Medical University, Hefei 230032, Anhui, China; Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China
| | - Qingqing Chen
- Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China
| | - Yinghui Ju
- Department of Pharmacy, Hefei Ion Medical Center, Hefei 230032, Anhui, China
| | - Weizu Li
- Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China.
| | - Weiping Li
- Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China; Anqing Medical and Pharmaceutical College, Anqing 246052, Anhui, China.
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Swapna Sasi US, Sindhu G, Raghu KG. Fructose- palmitate based high calorie induce steatosis in HepG2 cells via mitochondrial dysfunction: An in vitro approach. Toxicol In Vitro 2020; 68:104952. [PMID: 32730863 DOI: 10.1016/j.tiv.2020.104952] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/10/2020] [Accepted: 07/23/2020] [Indexed: 02/08/2023]
Abstract
A proper in vitro model for conducting research on high energy food induced steatosis via defective energy metabolism in the liver is not visible in the literature. The present study developed an in vitro model in HepG2 cell line to mimic high energy diet induced steatosis in liver via mitochondrial dysfunction. For this, HepG2 cells were treated with fructose (100 mM) and palmitate (100 μM) for about 24 h and subjected for biochemical analysis relevant to lipogenesis and mitochondrial biology. Our findings showed that fructose-palmitate treatment caused significant lipid accumulation and rise in lipogenic proteins. Further studies showed alteration in mitochondrial integrity, dynamics and oxidative phosphorylation. Mitochondrial integrity was affected by the dissipation of trans-membrane potential, surplus mitochondrial superoxide with calcium overload. Similarly, mitochondrial dynamics were altered with up regulation of mitochondrial fission proteins: DRP1 and FIS1, cytochrome c release, caspase-3 activity and apoptosis. Various components of the electron transport chain: complex I, II, III and IV were altered with significant depletion in oxygen consumption. Overall our findings illustrate the dominant role of mitochondria in the genesis of high fructose-palmitate induced steatosis in HepG2 cells. Since continuous high energy food consumption is the main inducer of steatosis, this model is found to be an ideal one for preliminary and basic research in the area of liver disease via mitochondrial dysfunction.
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Affiliation(s)
- U S Swapna Sasi
- Academy of Scientific & Innovative Research (AcSIR), CSIR-HRDC, Ghaziabad, Uttar Pradesh 201002, India; Biochemistry and Molecular Mechanism Laboratory, Agro-processing and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Thiruvananthapuram, Kerala, 695019, India.
| | - G Sindhu
- Biochemistry and Molecular Mechanism Laboratory, Agro-processing and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Thiruvananthapuram, Kerala, 695019, India.
| | - K G Raghu
- Academy of Scientific & Innovative Research (AcSIR), CSIR-HRDC, Ghaziabad, Uttar Pradesh 201002, India; Biochemistry and Molecular Mechanism Laboratory, Agro-processing and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Thiruvananthapuram, Kerala, 695019, India.
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Lainšček D, Šuštar U, Carter RN, Morton NM, Horvat S. Tst gene mediates protection against palmitate-induced inflammation in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2020; 527:1008-13. [PMID: 32444140 DOI: 10.1016/j.bbrc.2020.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/01/2020] [Indexed: 01/22/2023]
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Botta A, Elizbaryan K, Tashakorinia P, Lam NH, Sweeney G. An adiponectin-S1P autocrine axis protects skeletal muscle cells from palmitate-induced cell death. Lipids Health Dis 2020; 19:156. [PMID: 32611437 DOI: 10.1186/s12944-020-01332-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 06/17/2020] [Indexed: 12/15/2022] Open
Abstract
Background The prevalence of type 2 diabetes, obesity and their various comorbidities have continued to rise. In skeletal muscle lipotoxicity is well known to be a contributor to the development of insulin resistance. Here it was examined if the small molecule adiponectin receptor agonist AdipoRon mimicked the effect of adiponectin to attenuate palmitate induced reactive oxygen species (ROS) production and cell death in L6 skeletal muscle cells. Methods L6 cells were treated ±0.1 mM PA, and ± AdipoRon, then assays analyzing reactive oxygen species (ROS) production and cell death, and intracellular and extracellular levels of sphingosine-1 phosphate (S1P) were conducted. To determine the mechanistic role of S1P gain (using exogenous S1P or using THI) or loss of function (using the SKI-II) were conducted. Results Using both CellROX and DCFDA assays it was found that AdipoRon reduced palmitate-induced ROS production. Image-IT DEAD, MTT and LDH assays all indicated that AdipoRon reduced palmitate-induced cell death. Palmitate significantly increased intracellular accumulation of S1P, whereas in the presence of AdipoRon there was increased release of S1P from cells to extracellular medium. It was also observed that direct addition of extracellular S1P prevented palmitate-induced ROS production and cell death, indicating that S1P is acting in an autocrine manner. Pharmacological approaches to enhance or decrease S1P levels indicated that accumulation of intracellular S1P correlated with enhanced cell death. Conclusion This data indicates that increased extracellular levels of S1P in response to adiponectin receptor activation can activate S1P receptor-mediated signaling to attenuate lipotoxic cell death. Taken together these findings represent a possible novel mechanism for the protective action of adiponectin.
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Lochner A, Genade S, Genis A, Marais E, Salie R. Long-chain free fatty acids inhibit ischaemic preconditioning of the isolated rat heart. Mol Cell Biochem 2020; 473:111-32. [PMID: 32602016 DOI: 10.1007/s11010-020-03812-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 06/18/2020] [Indexed: 02/07/2023]
Abstract
We recently reported that non-preconditioned hearts from diet-induced obese rats showed, compared to controls, a significant reduction in infarct size after ischaemia/reperfusion, whilst ischaemic preconditioning was without effect. In view of the high circulating FFA concentration in diet rats, the aims of the present study were to: (i) compare the effect of palmitate on the preconditioning potential of hearts from age-matched controls and diet rats (ii) elucidate the effects of substrate manipulation on ischaemic preconditioning. Substrate manipulation was done with dichloroacetate (DCA), which enhances glucose oxidation and decreases fatty acid oxidation. Isolated hearts from diet rats, age-matched controls or young rats, were perfused in the working mode using the following substrates: glucose (10 mM); palmitate (1.2 mM)/3% albumin) + glucose (10 mM) (HiFA + G); palmitate (1.2 mM/3% albumin) (HiFA); palmitate (0.4 mM/3% albumin) + glucose(10 mM) (LoFA + G); palmitate (0.4 mM/3% albumin) (LoFA). Hearts were preconditioned with 3 × 5 min ischaemia/reperfusion, followed by 35 min coronary ligation and 60 min reperfusion for infarct size determination (tetrazolium method) or 20 min global ischaemia/10 or 30 min reperfusion for Western blotting (ERKp44/42, PKB/Akt). Preconditioning of glucose-perfused hearts from age-matched control (but not diet) rats reduced infarct size, activated ERKp44/42 and PKB/Akt and improved functional recovery during reperfusion (ii) perfusion with HiFA + G abolished preconditioning and activation of ERKp44/42 (iii) DCA pretreatment largely reversed the harmful effects of HiFA. Hearts from non-preconditioned diet rats exhibited smaller infarcts, but could not be preconditioned, regardless of the substrate. Similar results were obtained upon substrate manipulation of hearts from young rats. Abolishment of preconditioning in diet rats may be due to altered myocardial metabolic patterns resulting from changes in circulating FA. The harmful effects of HiFA were attenuated by stimulation of glycolysis and inhibition of FA oxidation.
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Wang J, Zhang X, Zhang L, Yan T, Wu B, Xu F, Jia Y. Silychristin A activates Nrf2-HO-1/SOD2 pathway to reduce apoptosis and improve GLP-1 production through upregulation of estrogen receptor α in GLUTag cells. Eur J Pharmacol 2020; 881:173236. [PMID: 32497626 DOI: 10.1016/j.ejphar.2020.173236] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/21/2020] [Accepted: 05/29/2020] [Indexed: 01/08/2023]
Abstract
Glucagon-like peptide-1 (GLP-1), a glucagon-like peptide secreted mainly from intestinal L cells, possesses the functions of promoting synthesis and secretion of insulin in pancreatic β-cells, and maintaining glucose homeostasis in an insulin-independent manner. Silychristin A, a major flavonolignan from silymarin, was reported to protect pancreatic β-cells from oxidative damage in streptozotocin (STZ)-induced diabetic rats. However, the role of silychristin A in the protection of intestinal L-cells is still unknown. Our current study demonstrated that palmitate (PA) inhibited protein expression of NF-E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and superoxide dismutase 2 (SOD2), and subsequently increased reactive oxygen species level to induce apoptosis and decrease GLP-1 content in intestinal L-cell line GLUTag cells. Pre-incubation of silychristin A effectively reversed PA-inactivated Nrf2-HO-1/SOD2 antioxidative pathway accompanied with decreased apoptosis level and increased GLP-1 level in GLUTag cells. As a potential target of silychristin A, estrogen receptor α was shown to be downregulated by PA stimulation, and the expression of which was improved by silychristin A in a concentration-dependent manner. Further study revealed that the treatment of estrogen receptor α antagonist MPP induced apoptosis and blocked the stimulation of GLP-1 production by silychristin A through the activation of Nrf2-HO-1/SOD2 pathway in GLUTag cells. Taken together, our study found silychristin A activated estrogen receptor α-dependent Nrf2-HO-1/SOD2 pathway to decrease apoptosis and upregulate GLP-1 production in GLUTag cells.
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Affiliation(s)
- Jinyu Wang
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, 110016, PR China
| | - Xiaoying Zhang
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, 110016, PR China
| | - Luxin Zhang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, 110016, PR China
| | - Tingxu Yan
- Faculty of Functional Food and Wine, Shenyang Pharmaceutical University, Shenyang, 110016, PR China
| | - Bo Wu
- Faculty of Functional Food and Wine, Shenyang Pharmaceutical University, Shenyang, 110016, PR China
| | - Fanxing Xu
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, 110016, PR China.
| | - Ying Jia
- Faculty of Functional Food and Wine, Shenyang Pharmaceutical University, Shenyang, 110016, PR China.
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Wang X, Tian J, Zhao Q, Yang N, Ying P, Peng X, Zou D, Zhu Y, Zhong R, Gao Y, Chang J, Miao X. Functional characterization of a low-frequency V1937I variant in FASN associated with susceptibility to esophageal squamous cell carcinoma. Arch Toxicol 2020; 94:2039-2046. [PMID: 32388819 DOI: 10.1007/s00204-020-02738-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/06/2020] [Indexed: 12/31/2022]
Abstract
Metabolic reprogramming has been regarded as one of the core hallmarks of cancer and increased de novo fatty acid synthesis has been documented in multiple tumors including esophageal squamous cell carcinoma (ESCC). Our previous exome-wide analyses found a Val1937Ile variant (rs17848945) in the 34th exon of fatty acid synthase (FASN) that showed a strong association with the risk of ESCC. In this study, we performed a series of functional assays to investigate the biological functions underlying this variant in the development of ESCC. We demonstrated that FASN was upregulated in ESCC and both knockdown and knockout of FASN significantly inhibited ESCC cell proliferation, suggesting a tumor promoter role for this gene in ESCC. Furthermore, the results showed that overexpression of FASN[I] in the ESCC cells substantially enhanced cell proliferation, compared with overexpression of FASN[V], or the control vector. Intriguingly, we found that the FASN[I] variant can enhance the enzyme activity of FASN, and, thus, increase the amount of the FASN end-product, palmitate in the ESCC cells. We also observed elevated palmitate levels in the plasma of the FASN[I] genotype carriers among a total of 632 healthy Chinese adults. In conclusion, our results suggested that the FASN V1937I variant influenced ESCC cell proliferation and susceptibility by altering the catabolic activity of FASN on palmitate. These findings may highlight an important role of palmitate metabolism in the development of ESCC and may contribute to the personalized medicine of this disease.
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Affiliation(s)
- Xiaoyang Wang
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jianbo Tian
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qianyu Zhao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Nan Yang
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Pingting Ying
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiating Peng
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Danyi Zou
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Zhu
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Rong Zhong
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Gao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jiang Chang
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Xiaoping Miao
- Department of Epidemiology and Biostatistics, Key Laboratory for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Vilas-Boas EA, Karabacz N, Marsiglio-Librais GN, Valle MMR, Nalbach L, Ampofo E, Morgan B, Carpinelli AR, Roma LP. Chronic activation of GPR40 does not negatively impact upon BRIN-BD11 pancreatic β-cell physiology and function. Pharmacol Rep 2020; 72:1725-1737. [PMID: 32274767 PMCID: PMC7704488 DOI: 10.1007/s43440-020-00101-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/18/2020] [Accepted: 03/21/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Free fatty acids (FFAs) are known for their dual effects on insulin secretion and pancreatic β-cell survival. Short-term exposure to FFAs, such as palmitate, increases insulin secretion. On the contrary, long-term exposure to saturated FFAs results in decreased insulin secretion, as well as triggering oxidative stress and endoplasmic reticulum (ER) stress, culminating in cell death. The effects of FFAs can be mediated either via their intracellular oxidation and consequent effects on cellular metabolism or via activation of the membrane receptor GPR40. Both pathways are likely to be activated upon both short- and long-term exposure to FFAs. However, the precise role of GPR40 in β-cell physiology, especially upon chronic exposure to FFAs, remains unclear. METHODS We used the GPR40 agonist (GW9508) and antagonist (GW1100) to investigate the impact of chronically modulating GPR40 activity on BRIN-BD11 pancreatic β-cells physiology and function. RESULTS We observed that chronic activation of GPR40 did not lead to increased apoptosis, and both proliferation and glucose-induced calcium entry were unchanged compared to control conditions. We also observed no increase in H2O2 or superoxide levels and no increase in the ER stress markers p-eIF2α, CHOP and BIP. As expected, palmitate led to increased H2O2 levels, decreased cell viability and proliferation, as well as decreased metabolism and calcium entry. These changes were not counteracted by the co-treatment of palmitate-exposed cells with the GPR40 antagonist GW1100. CONCLUSIONS Chronic activation of GPR40 using GW9508 does not negatively impact upon BRIN-BD11 pancreatic β-cells physiology and function. The GPR40 antagonist GW1100 does not protect against the deleterious effects of chronic palmitate exposure. We conclude that GPR40 is probably not involved in mediating the toxicity associated with chronic palmitate exposure.
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Affiliation(s)
- Eloisa Aparecida Vilas-Boas
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil.,Department of Biophysics, Center for Human and Molecular Biology, Saarland University, Universität Des Saarlandes, CIPMM, Geb. 48, 66421, Homburg/Saar, Germany
| | - Noémie Karabacz
- Department of Biophysics, Center for Human and Molecular Biology, Saarland University, Universität Des Saarlandes, CIPMM, Geb. 48, 66421, Homburg/Saar, Germany
| | | | - Maíra Melo Rezende Valle
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil
| | - Lisa Nalbach
- Institute for Clinical and Experimental Surgery, Saarland University, 66421, Homburg/Saar, Germany
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, 66421, Homburg/Saar, Germany
| | - Bruce Morgan
- Institute of Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, 66123, Saarbrücken, Germany
| | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil
| | - Leticia Prates Roma
- Department of Biophysics, Center for Human and Molecular Biology, Saarland University, Universität Des Saarlandes, CIPMM, Geb. 48, 66421, Homburg/Saar, Germany.
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Zhang J, Zhang R, Wang H, Yang K. Direct interspecies electron transfer stimulated by granular activated carbon enhances anaerobic methanation efficiency from typical kitchen waste lipid-rapeseed oil. Sci Total Environ 2020; 704:135282. [PMID: 31787308 DOI: 10.1016/j.scitotenv.2019.135282] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/28/2019] [Accepted: 10/28/2019] [Indexed: 06/10/2023]
Abstract
Due to long-chain fatty acids (LCFAs) and acidification, rapeseed oil as a typical lipid in kitchen waste is difficult to be biodegraded by anaerobic digestion. It has been reported that incorporation of some conductive materials into reactors treating complex organic matter could enhance reactor performance. In this study, the aim was to study this possibility of application of granular activated carbon (GAC) in anaerobic digestion of rapeseed oil. As expected, the GAC-amended reactor could significantly improve methane yield and reduce acidification. Besides, the GAC-amended broth could efficiently degrade palmitate into methane. Microbial community analysis showed that bacteria (Syntrophomonas) and methanogens (Methanosarcina) were greatly enriched on the GAC surface in GAC-amended system. These results, and the kwon of easy enrichment of Syntrophomonas on conductive materials or current-harvesting electrodes in methanogenic and/or electrogenic systems, suggest that Syntrophomonas could participate in direct interspecies electron transfer with Methanosarcina species, when GAC is available as an electron transfer mediator. Hence, the addition of GAC could efficiently, stably and environmentally enhance the methanogenic metabolism of rapeseed oil.
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Affiliation(s)
- Jing Zhang
- School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan 430072, China.
| | - Rongtang Zhang
- School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan 430072, China
| | - Hongyu Wang
- School of Civil Engineering, Wuhan University, Wuhan 430072, China
| | - Kai Yang
- School of Civil Engineering, Wuhan University, Wuhan 430072, China
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Takeuchi T, Masuno K, Umeda M, Tanaka A, Tominaga K. Palmitate induces apoptosis and inhibits osteogenic differentiation of human periodontal ligament stem cells. Arch Oral Biol 2020; 112:104681. [PMID: 32070866 DOI: 10.1016/j.archoralbio.2020.104681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 01/22/2020] [Accepted: 02/10/2020] [Indexed: 10/25/2022]
Abstract
OBJECTIVE The aim of the present study was to investigate the effect of palmitate on human periodontal ligament stem cells (PDLSCs). DESIGN PDLSCs were isolated from the third molars of healthy adult donors, and cultured in normal or osteogenic medium supplemented with palmitate (0, 100, or 250 μM) for 21 days. Cell proliferation was evaluated by measuring the amount of formazan at 6, 24, 48, and 72 h. Apoptosis was detected by ELISA and terminal deoxynucleotidyl transferase dUTP nick end labeling assay at days 3 and 7. Osteogenic differentiation was evaluated by measuring the alkaline phosphatase (ALP) activity, production of procollagen type I C-peptide and osteocalcin, mineralization, and mRNA expression of Runx2 at days 3, 7, 14, and 21. In addition, mRNA expression of IL-6 and IL-8 was measured at day 3. RESULTS Palmitate inhibited the proliferation, ALP activity, production of procollagen type I C-peptide and osteocalcin, mineralization, and mRNA expression of Runx2 in the cultured PDLSCs. Palmitate also induced apoptosis and mRNA expression of IL-6 and IL-8 in the PDLSCs. CONCLUSIONS The results of the present study demonstrate that palmitate induces apoptosis and inhibits osteogenic differentiation of PDLSCs. These findings may help clarify the relationship between palmitate and periodontal tissue regeneration.
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Affiliation(s)
- Tomoki Takeuchi
- Department of Oral Pathology, Osaka Dental University, Osaka, Japan.
| | - Kazuya Masuno
- Department of Innovations in Dental Education, Osaka Dental University, Osaka, Japan
| | - Makoto Umeda
- Department of Periodontology, Osaka Dental University, Osaka, Japan
| | - Akio Tanaka
- Department of Pathology, Osaka Dental University, Osaka, Japan
| | - Kazuya Tominaga
- Department of Oral Pathology, Osaka Dental University, Osaka, Japan
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Tricò D, Mengozzi A, Nesti L, Hatunic M, Gabriel Sanchez R, Konrad T, Lalić K, Lalić NM, Mari A, Natali A. Circulating palmitoleic acid is an independent determinant of insulin sensitivity, beta cell function and glucose tolerance in non-diabetic individuals: a longitudinal analysis. Diabetologia 2020; 63:206-218. [PMID: 31676981 DOI: 10.1007/s00125-019-05013-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 08/27/2019] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS Experimental studies suggest that the fatty acid palmitoleate may act as an adipocyte-derived lipid hormone (or 'lipokine') to regulate systemic metabolism. We investigated the relationship of circulating palmitoleate with insulin sensitivity, beta cell function and glucose tolerance in humans. METHODS Plasma NEFA concentration and composition were determined in non-diabetic individuals from the Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) study cohort at baseline (n = 1234) and after a 3 year follow-up (n = 924). Glucose tolerance, insulin secretion and beta cell function were assessed during an OGTT. Whole-body insulin sensitivity was measured by a hyperinsulinaemic-euglycaemic clamp (M/I) and OGTT (oral glucose insulin sensitivity index [OGIS]). The liver insulin resistance index was calculated using clinical and biochemical data. Body composition including fat mass was determined by bioelectrical impedance. RESULTS Circulating palmitoleate was proportional to fat mass (r = 0.21, p < 0.0001) and total NEFA levels (r = 0.19, p < 0.0001). It correlated with whole-body insulin sensitivity (M/I: standardised regression coefficient [std. β] = 0.16, p < 0.0001), liver insulin resistance (std. β = -0.14, p < 0.0001), beta cell function (potentiation: std. β = 0.08, p = 0.045) and glucose tolerance (2 h glucose: std. β = -0.24, p < 0.0001) after adjustment for age, sex, BMI, adiposity and other NEFA. High palmitoleate concentrations prevented the decrease in insulin sensitivity associated with excess palmitate (p = 0.0001). In a longitudinal analysis, a positive independent relationship was observed between changes in palmitoleate and insulin sensitivity over time (std. β = 0.07, p = 0.04). CONCLUSIONS/INTERPRETATION We demonstrated that plasma palmitoleate is an independent determinant of insulin sensitivity, beta cell function and glucose tolerance in non-diabetic individuals. These results support the role of palmitoleate as a beneficial lipokine released by adipose tissue to prevent the negative effects of adiposity and excess NEFA on systemic glucose metabolism.
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Affiliation(s)
- Domenico Tricò
- Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 67, 56126, Pisa, Italy.
- Institute of Life Sciences, Sant'Anna School of Advanced Studies, Pisa, Italy.
| | - Alessandro Mengozzi
- Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 67, 56126, Pisa, Italy
| | - Lorenzo Nesti
- Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 67, 56126, Pisa, Italy
| | - Mensud Hatunic
- Department of Endocrinology, Mater Misericordiae University Hospital, University College Dublin School of Medicine, Dublin, Ireland
| | | | - Thomas Konrad
- Institute for Metabolic Research, Goethe University, Frankfurt am Main, Germany
| | - Katarina Lalić
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Nebojša M Lalić
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Andrea Mari
- Institute of Neuroscience, National Research Council, Padua, Italy
| | - Andrea Natali
- Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 67, 56126, Pisa, Italy
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Xue RQ, Zhao M, Wu Q, Yang S, Cui YL, Yu XJ, Liu J, Zang WJ. Regulation of mitochondrial cristae remodelling by acetylcholine alleviates palmitate-induced cardiomyocyte hypertrophy. Free Radic Biol Med 2019; 145:103-117. [PMID: 31553938 DOI: 10.1016/j.freeradbiomed.2019.09.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 09/21/2019] [Indexed: 12/31/2022]
Abstract
Mitochondrial dysfunction is associated with obesity-induced cardiac remodelling. Recent research suggests that the cristae are the true bioenergetic components of cells. Acetylcholine (ACh), the major neurotransmitter of the vagus nerve, exerts cardio-protective effects against ischaemia. This study investigated the role of cristae remodelling in palmitate (PA)-induced neonatal rat cardiomyocyte hypertrophy and explored the beneficial effects of ACh. We found loose, fragmented and even lysed cristae in PA-treated neonatal cardiomyocytes along with declines in mitochondrial network and complex expression and overproduction of mitochondrial reactive oxygen species (ROS); these changes ultimately resulted in increased myocardial size. Overexpression of mitofilin by adenoviral infection partly improved cristae shape, mitochondrial network, and ATP content and attenuated cell hypertrophy. Interestingly, siRNA-mediated AMP-activated protein kinase (AMPK) silencing increased the number of cristae with a balloon-like morphology without disturbing mitofilin expression. Furthermore, AMPK knockdown abolished the effects of mitofilin overexpression on cristae remodelling and inhibited the interaction of mitofilin with sorting and assembly machinery 50 (Sam50) and coiled-coil helix coiled-coil helix domain-containing protein 3 (CHCHD3), two core components of the mitochondrial contact site and cristae organizing system (MICOS) complex. Intriguingly, ACh upregulated mitofilin expression and AMPK phosphorylation via the muscarinic ACh receptor (MAChR). Moreover, ACh enhanced protein-protein interactions between mitofilin and other components of the MICOS complex, thereby preventing PA-induced mitochondrial dysfunction and cardiomyocyte hypertrophy; however, these effects were abolished by AMPK silencing. Taken together, our data suggest that ACh improves cristae remodelling to defend against PA-induced myocardial hypertrophy, presumably by increasing mitofilin expression and activating AMPK to form the MICOS complex through MAChR. These results suggest new and promising therapeutic approaches targeting mitochondria to prevent lipotoxic cardiomyopathy.
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Affiliation(s)
- Run-Qing Xue
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China
| | - Ming Zhao
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China
| | - Qing Wu
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China
| | - Si Yang
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China
| | - Yan-Ling Cui
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China
| | - Xiao-Jiang Yu
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China
| | - Jiankang Liu
- Frontier Institute of Science and Technol, and Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Wei-Jin Zang
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, PR China.
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Abstract
Saturated fatty acids, such as palmitate, lead to circadian disruption. We aimed at studying the effect of low doses of palmitate on circadian metabolism and to decipher the mechanism by which fatty acids convey their effect in adipocytes. Mice were fed non-obesogenic doses of palm or olive oil and adipocytes were treated with palmitate and oleate. Cultured adipocytes treated with oleate showed increased AMPK activity and induced the expression of mitochondrial genes indicating increased fatty acid oxidation, while palmitate increased ACC activity and induced the expression of lipogenic genes, indicating increased fatty acid synthesis. Low doses of palmitate were sufficient to alter circadian rhythms, due to changes in the expression and/or activity of key metabolic proteins including GSK3β and AKT. Palmitate-induced AKT and GSK3β activation led to the phosphorylation of BMAL1 that resulted in low levels as well as high amplitude of circadian clock expression. In adipocytes, the detrimental metabolic alteration of palmitate manifests itself early on even at non-obesogenic levels. This is accompanied by modulating BMAL1 expression and phosphorylation levels, which lead to dampened clock gene expression.
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Affiliation(s)
- Yael Tal
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Nava Chapnik
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Oren Froy
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Abstract
PURPOSE OF REVIEW Obesity is a major risk factor for type 2 diabetes. Although adipose tissue allows storage of excess calories in periods of overnutrition, in obesity, adipose tissue metabolism becomes dysregulated and can promote metabolic diseases. This review discusses recent advances in understandings how adipocyte metabolism impacts metabolic homeostasis. RECENT FINDINGS The ability of adipocytes to synthesize lipids from glucose is a marker of metabolic fitness, e.g., low de novo lipogenesis (DNL) in adipocytes correlates with insulin resistance in obesity. Adipocyte DNL may promote synthesis of special "insulin sensitizing" signaling lipids that act hormonally. However, each metabolic intermediate in the DNL pathway (i.e., citrate, acetyl-CoA, malonyl-CoA, and palmitate) also has second messenger functions. Mounting evidence suggests these signaling functions may also be important for maintaining healthy adipocytes. While adipocyte DNL contributes to lipid storage, lipid precursors may have additional second messenger functions critical for maintaining adipocyte health, and thus systemic metabolic homeostasis.
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Affiliation(s)
- Wen-Yu Hsiao
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA, 01605, USA
| | - David A Guertin
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA, 01605, USA.
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Abstract
Nonalcoholic fatty liver disease is a major public health burden. Although many features of nonalcoholic fatty liver disease pathogenesis are known, the specific mechanisms and susceptibilities that determine an individual's risk of developing nonalcoholic steatohepatitis versus isolated steatosis are not well delineated. The predominant and defining histologic and imaging characteristic of nonalcoholic fatty liver disease is the accumulation of lipids. Dysregulation of lipid homeostasis in hepatocytes leads to transient generation or accumulation of toxic lipids that result in endoplasmic reticulum (ER) stress with inflammation, hepatocellular damage, and apoptosis. ER stress activates the unfolded protein response (UPR) which is classically viewed as an adaptive pathway to maintain protein folding homeostasis. Recent studies have uncovered the contribution of the UPR sensors in the regulation of hepatic steatosis and in the cellular response to lipotoxic stress. Interestingly, the UPR sensors can be directly activated by toxic lipids, independently of the accumulation of misfolded proteins, termed lipotoxic and proteotoxic stress, respectively. The dual function of the UPR sensors in protein and lipid homeostasis suggests that these two types of stress are interconnected likely due to the central role of the ER in protein folding and trafficking and lipid biosynthesis and trafficking, such that perturbations in either impact the function of the ER and activate the UPR sensors in an effort to restore homeostasis. The precise molecular similarities and differences between proteotoxic and lipotoxic ER stress are beginning to be understood. Herein, we provide an overview of the mechanisms involved in the activation and cross-talk between the UPR sensors, hepatic lipid metabolism, and lipotoxic stress, and discuss the possible therapeutic potential of targeting the UPR in nonalcoholic fatty liver disease.
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Affiliation(s)
- Myeong Jun Song
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States of America; Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States of America.
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Lytrivi M, Castell AL, Poitout V, Cnop M. Recent Insights Into Mechanisms of β-Cell Lipo- and Glucolipotoxicity in Type 2 Diabetes. J Mol Biol 2019; 432:1514-1534. [PMID: 31628942 DOI: 10.1016/j.jmb.2019.09.016] [Citation(s) in RCA: 184] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 09/15/2019] [Accepted: 09/16/2019] [Indexed: 12/24/2022]
Abstract
The deleterious effects of chronically elevated free fatty acid (FFA) levels on glucose homeostasis are referred to as lipotoxicity, and the concurrent exposure to high glucose may cause synergistic glucolipotoxicity. Lipo- and glucolipotoxicity have been studied for over 25 years. Here, we review the current evidence supporting the role of pancreatic β-cell lipo- and glucolipotoxicity in type 2 diabetes (T2D), including lipid-based interventions in humans, prospective epidemiological studies, and human genetic findings. In addition to total FFA quantity, the quality of FFAs (saturation and chain length) is a key determinant of lipotoxicity. We discuss in vitro and in vivo experimental models to investigate lipo- and glucolipotoxicity in β-cells and describe experimental pitfalls. Lipo- and glucolipotoxicity adversely affect many steps of the insulin production and secretion process. The molecular mechanisms underpinning lipo- and glucolipotoxic β-cell dysfunction and death comprise endoplasmic reticulum stress, oxidative stress and mitochondrial dysfunction, impaired autophagy, and inflammation. Crosstalk between these stress pathways exists at multiple levels and may aggravate β-cell lipo- and glucolipotoxicity. Lipo- and glucolipotoxicity are therapeutic targets as several drugs impact the underlying stress responses in β-cells, potentially contributing to their glucose-lowering effects in T2D.
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Affiliation(s)
- Maria Lytrivi
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Anne-Laure Castell
- CRCHUM, Montréal, QC, Canada; Department of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Vincent Poitout
- CRCHUM, Montréal, QC, Canada; Department of Medicine, Université de Montréal, Montréal, QC, Canada.
| | - Miriam Cnop
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium.
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Guo Q, Wei X, Hu H, Yang D, Zhang B, Fan X, Liu J, He H, Oh Y, Wu Q, Zhang Y, Wang C, Liu C, Gu N. The saturated fatty acid palmitate induces insulin resistance through Smad3-mediated down-regulation of FNDC5 in myotubes. Biochem Biophys Res Commun 2019; 520:619-626. [PMID: 31623832 DOI: 10.1016/j.bbrc.2019.10.077] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 10/09/2019] [Indexed: 12/16/2022]
Abstract
Elevated plasma free fatty acid (FFA) levels are associated with insulin resistance and can cause lipotoxicity in skeletal muscles. In response to FFAs, skeletal muscle can secrete a variety of cytokines. Irisin, one such muscle-secreted cytokine, can improve glucose tolerance, glucose uptake, and lipid metabolism. It is produced by the transmembrane protein fibronectin type Ⅲ domain containing 5 (FNDC5) by specific proteases. The purpose of this study was to investigate the regulatory mechanisms of the FNDC5 response to palmitate and their relationships with insulin resistance in C2C12 myotubes. RNA sequencing analysis results from C2C12 myotubes treated with palmitate showed that palmitate could activate the TGF-β signaling pathway. Palmitate directly affected the expression of Smad3, but not its phosphorylation level, in C2C12 myotubes. Furthermore, knockdown and knockout of Smad3 alleviated the inhibitory effect of palmitate on the expression of FNDC5. In contrast, overexpression of Smad3 aggravated the inhibition of FNDC5 expression. There is a Smad3 binding motif in the -660 bp to -649 bp region of the Fndc5 promoter. CRISPR/Cas9 knockout of this region also alleviated the inhibition of FNDC5 expression in response to palmitate. More importantly, inhibition of FNDC5 expression mediated by Smad3 led to a decrease in insulin sensitivity in C2C12 myotubes. Collectively, these findings suggest that palmitate could induce insulin resistance through Smad3-mediated down-regulation of the Fndc5 gene.
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Affiliation(s)
- Qian Guo
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Xiangjuan Wei
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Hailong Hu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - DaQian Yang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Boya Zhang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Xingpei Fan
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Jing Liu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Hongjuan He
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yuri Oh
- Faculty of Education, Wakayama University, Wakayama, Japan
| | - Qiong Wu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yao Zhang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Changlin Wang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Chuanpeng Liu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Ning Gu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
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Mitchell DA, Pendleton LC, Deschenes RJ. In Vitro Assays to Monitor the Enzymatic Activities of zDHHC Protein Acyltransferases. Methods Mol Biol 2019; 2009:169-177. [PMID: 31152403 DOI: 10.1007/978-1-4939-9532-5_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A family of zDHHC protein acyltransferase (PAT) enzymes catalyze the S-palmitoylation of target proteins via a two-step mechanism. The first step involves transfer of palmitate from the palmitoyl-CoA donor to the active site cysteine of the zDHHC PAT enzyme, releasing reduced CoA (CoASH). In the second step, the palmitoyl-PAT intermediate thioester reacts with a cysteine side chain within the target substrate to produce the palmitoylated substrate product or, in the absence of a protein substrate, the palmitoyl-PAT intermediate thioester is hydrolyzed and releases palmitate. Formation and resolution of the palmitoyl-PAT intermediate complex (autopalmitoylation) is measured using a coupled enzyme system that monitors the production of CoASH via reduction of NAD+ by the α-ketoglutarate dehydrogenase complex. This assay can be used to isolate and characterize modulators of autopalmitoylation and is scalable to high-throughput screening (HTS). A second fluorescence-based assay is described that monitors the hydrolysis of the palmitoyl-PAT thioester linked intermediate by thin-layer chromatography using a palmitoyl-CoA analog, BODIPY®-C12:0-CoA, as a substrate. These two assays provide a methodology to quantify the first enzymatic step of the two-step zDHHC PAT reaction.
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Affiliation(s)
- David A Mitchell
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Laura C Pendleton
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Robert J Deschenes
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
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Nisr RB, Shah DS, Ganley IG, Hundal HS. Proinflammatory NFkB signalling promotes mitochondrial dysfunction in skeletal muscle in response to cellular fuel overloading. Cell Mol Life Sci 2019; 76:4887-4904. [PMID: 31101940 PMCID: PMC6881256 DOI: 10.1007/s00018-019-03148-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 11/29/2022]
Abstract
Sustained nutrient (fuel) excess, as occurs during obesity and diabetes, has been linked to increased inflammation, impaired mitochondrial homeostasis, lipotoxicity, and insulin resistance in skeletal muscle. Precisely how mitochondrial dysfunction is initiated and whether it contributes to insulin resistance in this tissue remains a poorly resolved issue. Herein, we examine the contribution that an increase in proinflammatory NFkB signalling makes towards regulation of mitochondrial bioenergetics, morphology, and dynamics and its impact upon insulin action in skeletal muscle cells subject to chronic fuel (glucose and palmitate) overloading. We show sustained nutrient excess of L6 myotubes promotes activation of the IKKβ-NFkB pathway (as judged by a six-fold increase in IL-6 mRNA expression; an NFkB target gene) and that this was associated with a marked reduction in mitochondrial respiratory capacity (>50%), a three-fold increase in mitochondrial fragmentation and 2.5-fold increase in mitophagy. Under these circumstances, we also noted a reduction in the mRNA and protein abundance of PGC1α and that of key mitochondrial components (SDHA, ANT-1, UCP3, and MFN2) as well as an increase in cellular ROS and impaired insulin action in myotubes. Strikingly, pharmacological or genetic repression of NFkB activity ameliorated disturbances in mitochondrial respiratory function/morphology, attenuated loss of SDHA, ANT-1, UCP3, and MFN2 and mitigated the increase in ROS and the associated reduction in myotube insulin sensitivity. Our findings indicate that sustained oversupply of metabolic fuel to skeletal muscle cells induces heightened NFkB signalling and that this serves as a critical driver for disturbances in mitochondrial function and morphology, redox status, and insulin signalling.
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Affiliation(s)
- Raid B Nisr
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Dinesh S Shah
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Ian G Ganley
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
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