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Li L, Lixia D, Gan G, Li J, Yang L, Wu Y, Fang Z, Zhang X. Astrocytic HILPDA promotes lipid droplets generation to drive cognitive dysfunction in mice with sepsis-associated encephalopathy. CNS Neurosci Ther 2024; 30:e14758. [PMID: 38757390 PMCID: PMC11099789 DOI: 10.1111/cns.14758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 05/18/2024] Open
Abstract
AIMS Sepsis-associated encephalopathy (SAE) is manifested as a spectrum of disturbed cerebral function ranging from mild delirium to coma. However, the pathogenesis of SAE has not been clearly elucidated. Astrocytes play important roles in maintaining the function and metabolism of the brain. Most recently, it has been demonstrated that disorders of lipid metabolism, especially lipid droplets (LDs) dyshomeostasis, are involved in a variety of neurodegenerative diseases. The aim of this study was to investigate whether LDs are involved in the underlying mechanism of SAE. METHODS The open field test, Y-maze test, and contextual fear conditioning test (CFCT) were used to test cognitive function in SAE mice. Lipidomics was utilized to investigate alterations in hippocampal lipid metabolism in SAE mice. Western blotting and immunofluorescence labeling were applied for the observation of related proteins. RESULTS In the current study, we found that SAE mice showed severe cognitive dysfunction, including spatial working and contextual memory. Meanwhile, we demonstrated that lipid metabolism was widely dysregulated in the hippocampus by using lipidomic analysis. Furthermore, western blotting and immunofluorescence confirmed that LDs accumulation in hippocampal astrocytes was involved in the pathological process of cognitive dysfunction in SAE mice. We verified that LDs can be inhibited by specifically suppress hypoxia-inducible lipid droplet-associated protein (HILPDA) in astrocytes. Meanwhile, cognitive dysfunction in SAE was ameliorated by reducing A1 astrocyte activation and inhibiting presynaptic membrane transmitter release. CONCLUSION The accumulation of astrocytic lipid droplets plays a crucial role in the pathological process of SAE. HILPDA is an attractive therapeutic target for lipid metabolism regulation and cognitive improvement in septic patients.
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Affiliation(s)
- Ling Li
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of PediatricXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
| | - Du Lixia
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
| | - Guifen Gan
- Department of Critical Care MedicineQinghai University Affiliated HospitalXiningQinghaiChina
| | - Jin Li
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
| | - Lin Yang
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
| | - You Wu
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
| | - Zongping Fang
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Translational Research Institute of Brain and Brain‐Like IntelligenceShanghai Fourth People's HospitalSchool of MedicineTongji UniversityShanghaiChina
- Department of Critical Care MedicineShanghai Fourth People's HospitalSchool of MedicineTongji UniversityShanghaiChina
| | - Xijing Zhang
- Department of Critical Care MedicineXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
- Department of Anesthesiology and Perioperative Medicine and Department of Intensive Care UnitXijing HospitalFourth Military Medical UniversityXi'anShaanxiChina
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Wang S, Lu Y, Chi T, Zhang Y, Zhao Y, Guo H, Feng L. Identification of ferroptosis-related genes in type 2 diabetes mellitus based on machine learning. Immun Inflamm Dis 2023; 11:e1036. [PMID: 37904700 PMCID: PMC10566453 DOI: 10.1002/iid3.1036] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 09/05/2023] [Accepted: 09/17/2023] [Indexed: 11/01/2023] Open
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM), which has a high incidence and several harmful consequences, poses a severe danger to human health. Research on the function of ferroptosis in T2DM is increasing. This study uses bioinformatics techniques identify new diagnostic T2DM biomarkers associated with ferroptosis. METHODS To identify ferroptosis-related genes (FRGs) that are differentially expressed between T2DM patients and healthy individuals, we first obtained T2DM sequencing data and FRGs from the Gene Expression Omnibus (GEO) database and FerrDb database. Then, drug-gene interaction networks and competitive endogenous RNA (ceRNA) networks linked to the marker genes were built after marker genes were filtered by two machine learning algorithms (LASSO and SVM-RFE algorithms). Finally, to confirm the expression of marker genes, the GSE76895 dataset was utilized. The protein and RNA expression of some marker genes in T2DM and nondiabetic tissues was also examined by Western blotting, immunohistochemistry (IHC), immunofluorescence (IF) and quantitative real-time PCR (qRT-PCR). RESULTS We obtained 58 differentially expressed genes (DEGs) associated with ferroptosis. GO and KEGG enrichment analyses showed that these DEGs were significantly enriched in hypoxia and ferroptosis. Subsequently, eight marker genes (SCD, CD44, HIF1A, BCAT2, MTF1, HILPDA, NR1D2, and MYCN) were screened by LASSO and SVM-RFE machine learning algorithms, and a model was constructed based on these eight genes. This model also has high diagnostic power. In addition, based on these eight genes, we obtained 48 drugs and constructed a complex ceRNA network map. Finally, Western blotting, IHC, IF, and qRT-PCR results of clinical samples further confirmed the results of public databases. CONCLUSIONS The diagnosis and aetiology of T2DM can be greatly aided by eight FRGs, providing novel therapeutic avenues.
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Affiliation(s)
- Sen Wang
- Department of Medical Ultrasound, Shandong Medicine and Health Key Laboratory of Abdominal Medical Imaging, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qian Foshan HospitalShandong First Medical UniversityJinanShandongChina
| | - Yongpan Lu
- Department of Plastic Surgery, The First Clinical Medical College, Shandong University of Traditional Chinese MedicineThe First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qian Foshan HospitalJinanShandongChina
| | - Tingting Chi
- Department of Acupuncture and RehabilitationThe Affiliated Qingdao Hai Ci Hospital of Qingdao University (West Hospital Area)QingdaoShandongChina
| | - Yixin Zhang
- Department of Medical Ultrasound, Shandong Medicine and Health Key Laboratory of Abdominal Medical Imaging, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qian Foshan HospitalShandong First Medical UniversityJinanShandongChina
| | - Yuli Zhao
- Department of Medical Ultrasound, Shandong Medicine and Health Key Laboratory of Abdominal Medical Imaging, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qian Foshan HospitalShandong First Medical UniversityJinanShandongChina
| | - Huimin Guo
- Department of Medical Ultrasound, Shandong Medicine and Health Key Laboratory of Abdominal Medical Imaging, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qian Foshan HospitalShandong First Medical UniversityJinanShandongChina
| | - Li Feng
- Department of Medical Ultrasound, Shandong Medicine and Health Key Laboratory of Abdominal Medical Imaging, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qian Foshan HospitalShandong First Medical UniversityJinanShandongChina
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Ortuño-Sahagún D, Enterría-Rosales J, Izquierdo V, Griñán-Ferré C, Pallàs M, González-Castillo C. The Role of the miR-17-92 Cluster in Autophagy and Atherosclerosis Supports Its Link to Lysosomal Storage Diseases. Cells 2022; 11:cells11192991. [PMID: 36230953 PMCID: PMC9564236 DOI: 10.3390/cells11192991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/08/2022] [Accepted: 09/20/2022] [Indexed: 12/24/2022] Open
Abstract
Establishing the role of non-coding RNA (ncRNA), especially microRNAs (miRNAs), in the regulation of cell function constitutes a current research challenge. Two to six miRNAs can act in clusters; particularly, the miR-17-92 family, composed of miR-17, miR-18a, miR-19a, miR-20a, miR-19b-1, and miR-92a is well-characterized. This cluster functions during embryonic development in cell differentiation, growth, development, and morphogenesis and is an established oncogenic cluster. However, its role in the regulation of cellular metabolism, mainly in lipid metabolism and autophagy, has received less attention. Here, we argue that the miR-17-92 cluster is highly relevant for these two processes, and thus, could be involved in the study of pathologies derived from lysosomal deficiencies. Lysosomes are related to both processes, as they control cholesterol flux and regulate autophagy. Accordingly, we compiled, analyzed, and discussed current evidence that highlights the cluster's fundamental role in regulating cellular energetic metabolism (mainly lipid and cholesterol flux) and atherosclerosis, as well as its critical participation in autophagy regulation. Because these processes are closely related to lysosomes, we also provide experimental data from the literature to support our proposal that the miR-17-92 cluster could be involved in the pathogenesis and effects of lysosomal storage diseases (LSD).
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Affiliation(s)
- Daniel Ortuño-Sahagún
- Laboratorio de Neuroinmunobiología Molecular, Instituto de Investigación en Ciencias Biomédicas (IICB) CUCS, Universidad de Guadalajara, Guadalajara 44340, Jalisco, Mexico
- Correspondence: (D.O.-S.); (C.G.-C.)
| | - Julia Enterría-Rosales
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, Zapopan 45201, Jalisco, Mexico
| | - Vanesa Izquierdo
- Pharmacology and Toxicology Section and Institute of Neuroscience, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08007 Barcelona, Spain
| | - Christian Griñán-Ferré
- Pharmacology and Toxicology Section and Institute of Neuroscience, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08007 Barcelona, Spain
| | - Mercè Pallàs
- Pharmacology and Toxicology Section and Institute of Neuroscience, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08007 Barcelona, Spain
| | - Celia González-Castillo
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, Zapopan 45201, Jalisco, Mexico
- Correspondence: (D.O.-S.); (C.G.-C.)
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Grabner GF, Xie H, Schweiger M, Zechner R. Lipolysis: cellular mechanisms for lipid mobilization from fat stores. Nat Metab 2021; 3:1445-1465. [PMID: 34799702 DOI: 10.1038/s42255-021-00493-6] [Citation(s) in RCA: 226] [Impact Index Per Article: 75.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022]
Abstract
The perception that intracellular lipolysis is a straightforward process that releases fatty acids from fat stores in adipose tissue to generate energy has experienced major revisions over the last two decades. The discovery of new lipolytic enzymes and coregulators, the demonstration that lipophagy and lysosomal lipolysis contribute to the degradation of cellular lipid stores and the characterization of numerous factors and signalling pathways that regulate lipid hydrolysis on transcriptional and post-transcriptional levels have revolutionized our understanding of lipolysis. In this review, we focus on the mechanisms that facilitate intracellular fatty-acid mobilization, drawing on canonical and noncanonical enzymatic pathways. We summarize how intracellular lipolysis affects lipid-mediated signalling, metabolic regulation and energy homeostasis in multiple organs. Finally, we examine how these processes affect pathogenesis and how lipolysis may be targeted to potentially prevent or treat various diseases.
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Affiliation(s)
- Gernot F Grabner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Hao Xie
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Martina Schweiger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
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Grachan JJ, Kery M, Giaccia AJ, Denko NC, Papandreou I. Lipid droplet storage promotes murine pancreatic tumor growth. Oncol Rep 2021; 45:21. [PMID: 33649859 PMCID: PMC8889526 DOI: 10.3892/or.2021.7972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/20/2020] [Indexed: 11/06/2022] Open
Abstract
Hypoxia Inducible Lipid Droplet Associated (HILPDA) is frequently overexpressed in tumors and promotes neutral lipid storage. The impact of Hilpda on pancreatic ductal adenocarcinoma (PDAC) tumor growth is not known. In order to evaluate Hilpda‑dependent lipid storage mechanisms, expression of Hilpda in murine pancreatic cells (KPC) was genetically manipulated. Lipid droplet (LD) abundance and triglyceride content in vitro were measured, and model tumor growth in nu/nu mice was determined. The results showed that excess lipid supply increased triglyceride storage and LD formation in KPC cells in a HILPDA‑dependent manner. Contrary to published results, inhibition of Adipose Triglyceride Lipase (ATGL) did not ameliorate the triglyceride abundance differences between Hilpda WT and KO cells. Hilpda ablation significantly decreased the growth rate of model tumors in immunocompromised mice. In conclusion, Hilpda is a positive regulator of triglyceride storage and lipid droplet formation in murine pancreatic cancer cells in vitro and lipid accumulation and tumor growth in vivo. Our data suggest that deregulated ATGL is not responsible for the absence of LDs in KO cells in this context.
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Affiliation(s)
- Jeremy J. Grachan
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Martin Kery
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Amato J. Giaccia
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Nicholas C. Denko
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Ioanna Papandreou
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
- Correspondence to: Dr Ioanna Papandreou, Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, 420 W. 12th Avenue, Columbus, OH 43210, USA, E-mail:
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van Dierendonck XAMH, de la Rosa Rodriguez MA, Georgiadi A, Mattijssen F, Dijk W, van Weeghel M, Singh R, Borst JW, Stienstra R, Kersten S. HILPDA Uncouples Lipid Droplet Accumulation in Adipose Tissue Macrophages from Inflammation and Metabolic Dysregulation. Cell Rep 2021; 30:1811-1822.e6. [PMID: 32049012 DOI: 10.1016/j.celrep.2020.01.046] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/10/2019] [Accepted: 01/15/2020] [Indexed: 01/15/2023] Open
Abstract
Obesity leads to a state of chronic, low-grade inflammation that features the accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid-droplet accumulation in the development of obesity-induced adipose-tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency markedly reduced intracellular lipid levels and accumulation of fluorescently labeled fatty acids. Decreased lipid storage in HILPDA-deficient macrophages can be rescued by inhibition of adipose triglyceride lipase (ATGL) and is associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency does not alter inflammatory and metabolic parameters, despite markedly reducing lipid accumulation in macrophages. Overall, we find that HILPDA is a lipid-inducible, physiological inhibitor of ATGL-mediated lipolysis in macrophages and uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Our data question the contribution of lipid droplet accumulation in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.
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Affiliation(s)
- Xanthe A M H van Dierendonck
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands; Department of Internal Medicine, Radboud University Medical Center, Geert Grooteplein 8, 6525 GA Nijmegen, the Netherlands
| | - Montserrat A de la Rosa Rodriguez
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Anastasia Georgiadi
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Frits Mattijssen
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Wieneke Dijk
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Michel van Weeghel
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands; Gastroenterology and Metabolism, Amsterdam Cardiovascular Sciences, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
| | - Rajat Singh
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 505D, Bronx, NY 10461, USA
| | - Jan Willem Borst
- Laboratory of Biochemistry, Microspectroscopy Research Facility, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Rinke Stienstra
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands; Department of Internal Medicine, Radboud University Medical Center, Geert Grooteplein 8, 6525 GA Nijmegen, the Netherlands.
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands.
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Sheng Y, Li J, Yang Y, Lu Y. Hypoxia-inducible lipid droplet-associated (HILPDA) facilitates the malignant phenotype of lung adenocarcinoma cells in vitro through modulating cell cycle pathways. Tissue Cell 2021; 70:101495. [PMID: 33535136 DOI: 10.1016/j.tice.2021.101495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/10/2020] [Accepted: 01/11/2021] [Indexed: 12/31/2022]
Abstract
BACKGROUND Hypoxia-inducible lipid droplet-associated (HILPDA) is considered to have tumorigenic activity, but its function in lung adenocarcinoma (LUAD) is rarely known. This work aimed to assess the regulatory functions as well as the in-depth mechanism of HILPDA in LUAD. METHODS The expression of HILPDA in LUAD tissues was analyzed based on TCGA database, and then qRT-PCR was performed to confirm the HILPDA expression in LUAD cell lines. Kaplan-Meier analysis was used to measure the correlation of HILPDA expression and overall survival in patients with LUAD. Then, Cell-Counting Kit-8 (CCK-8), colony formation and transwell assays were performed to detect cell proliferation, invasion and migration. Moreover, the pathways closely related to the high HILPDA expression was analyzed by Kyoto Encyclopedia of genes and Genomes (KEGG) analysis. The levels of Cell cycle pathway-related proteins were assessed using western blotting. RESULTS Herein, we revealed that HILPDA was expressed at high levels in LUAD tissues and cell lines, and LUAD patients with the higher HILPDA expression presented the shorter survival time. Down-regulation of HILPDA in Calu-3 cells can retard cell proliferation, migration and invasion as well as arrest cells in the G1 phase, whereas overexpression of HILPDA in A549 cells presented a marked promotion on these phenotypes. Moreover, we surveyed that knockdown of HILPDA restrained the activation of cell cycle pathway, while up-regulation of HILPDA led to opponent outcomes. CONCLUSIONS In summing, HILPDA may act as an oncogenic factor in LUAD cells via modulating cell cycle pathway, which represent a novel biomarker of tumorigenesis in LUAD patients.
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Affiliation(s)
- Yanrui Sheng
- Department of Clinical Laboratory, Jining No.1 People's Hospital, Jining, PR China
| | - Jinlong Li
- Department of Respiratory Medicine, Suixi County Hospital, Huaibei, PR China
| | - Yanna Yang
- Department of Respiratory and Critical Care Medicine, Central Hospital Affiliated to Shandong First Medical University, Jinan, PR China
| | - Yingyun Lu
- Department of Rehabilitation Medicine, Shandong Provincial Third Hospital, Cheeloo College of Medicine, Shandong University, Jinan, PR China.
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de la Rosa Rodriguez MA, Deng L, Gemmink A, van Weeghel M, Aoun ML, Warnecke C, Singh R, Borst JW, Kersten S. Hypoxia-inducible lipid droplet-associated induces DGAT1 and promotes lipid storage in hepatocytes. Mol Metab 2021; 47:101168. [PMID: 33465519 PMCID: PMC7881268 DOI: 10.1016/j.molmet.2021.101168] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/08/2021] [Accepted: 01/12/2021] [Indexed: 12/26/2022] Open
Abstract
Objective Storage of triglycerides in lipid droplets is governed by a set of lipid droplet-associated proteins. One of these lipid droplet-associated proteins, hypoxia-inducible lipid droplet-associated (HILPDA), was found to impair lipid droplet breakdown in macrophages and cancer cells by inhibiting adipose triglyceride lipase. Here, we aimed to better characterize the role and mechanism of action of HILPDA in hepatocytes. Methods We performed studies in HILPDA-deficient and HILPDA-overexpressing liver cells, liver slices, and mice. The functional role and physical interactions of HILPDA were investigated using a variety of biochemical and microscopic techniques, including real-time fluorescence live-cell imaging and Förster resonance energy transfer-fluorescence lifetime imaging microscopy (FRET-FLIM). Results Levels of HILPDA were markedly induced by fatty acids in several hepatoma cell lines. Hepatocyte-specific deficiency of HILPDA in mice modestly but significantly reduced hepatic triglycerides in mice with non-alcoholic steatohepatitis. Similarly, deficiency of HILPDA in mouse liver slices and primary hepatocytes reduced lipid storage and accumulation of fluorescently-labeled fatty acids in lipid droplets, respectively, which was independent of adipose triglyceride lipase. Fluorescence microscopy showed that HILPDA partly colocalizes with lipid droplets and with the endoplasmic reticulum, is especially abundant in perinuclear areas, and mainly associates with newly added fatty acids. Real-time fluorescence live-cell imaging further revealed that HILPDA preferentially localizes to lipid droplets that are being remodeled. Overexpression of HILPDA in liver cells increased the activity of diacylglycerol acyltransferases (DGAT) and DGAT1 protein levels, concurrent with increased lipid storage. Confocal microscopy coupled to FRET-FLIM analysis demonstrated that HILPDA physically interacts with DGAT1 in living liver cells. The stimulatory effect of HILPDA on lipid storage via DGAT1 was corroborated in adipocytes. Conclusions Our data indicate that HILPDA physically interacts with DGAT1 and increases DGAT activity. Our findings suggest a novel regulatory mechanism by which fatty acids promote triglyceride synthesis and storage. HILPDA expression is induced by fatty acids in hepatoma cells. HILPDA deficiency modestly decreases liver triglyceride storage in mice with NASH. HILPDA preferentially associates with newly synthesized lipid droplets and active lipid droplets. HILPDA promotes lipid storage at least in part independently of ATGL. HILPDA physically interacts and induces DGAT1.
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Affiliation(s)
- Montserrat A de la Rosa Rodriguez
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands
| | - Lei Deng
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands
| | - Anne Gemmink
- Department of Nutrition and Movement Sciences, Maastricht University Medical Center+, Maastricht, 6200 MD, the Netherlands
| | - Michel van Weeghel
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105 AZ, the Netherlands
| | - Marie Louise Aoun
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 505D, Bronx, NY, 10461, USA
| | - Christina Warnecke
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Rajat Singh
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 505D, Bronx, NY, 10461, USA
| | - Jan Willem Borst
- Laboratory of Biochemistry, Microspectroscopy Research Facility, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands
| | - Sander Kersten
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands.
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9
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Povero D, Johnson SM, Liu J. Hypoxia, hypoxia-inducible gene 2 (HIG2)/HILPDA, and intracellular lipolysis in cancer. Cancer Lett 2020; 493:71-79. [PMID: 32818550 PMCID: PMC11218043 DOI: 10.1016/j.canlet.2020.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/27/2020] [Accepted: 06/13/2020] [Indexed: 12/16/2022]
Abstract
Tumor tissues are chronically exposed to hypoxia owing to aberrant vascularity. Hypoxia induces metabolic alterations in cancer, thereby promoting aggressive malignancy and metastasis. While previous efforts largely focused on adaptive responses in glucose and glutamine metabolism, recent studies have begun to yield important insight into the hypoxic regulation of lipid metabolic reprogramming in cancer. Emerging evidence points to lipid droplet (LD) accumulation as a hallmark of hypoxic cancer cells. One critical underlying mechanism involves the inhibition of adipose triglyceride lipase (ATGL)-mediated intracellular lipolysis by a small protein encoded by hypoxia-inducible gene 2 (HIG2), also known as hypoxia inducible lipid droplet associated (HILPDA). In this review we summarize and discuss recent key findings on hypoxia-dependent regulation of metabolic adaptations especially lipolysis in cancer. We also pose several questions and hypotheses pertaining to the metabolic impact of lipolytic regulation in cancer under hypoxia and during hypoxia-reoxygenation transition.
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Affiliation(s)
- Davide Povero
- From Department of Biochemistry and Molecular Biology, Rochester, MN, 55905, USA; Division of Endocrinology, Rochester, MN, 55905, USA
| | - Scott M Johnson
- From Department of Biochemistry and Molecular Biology, Rochester, MN, 55905, USA; Mayo Clinic College of Medicine & Science, Rochester, MN, 55905, USA; Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, 55905, USA
| | - Jun Liu
- From Department of Biochemistry and Molecular Biology, Rochester, MN, 55905, USA; Division of Endocrinology, Rochester, MN, 55905, USA.
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10
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Adipocyte lipolysis: from molecular mechanisms of regulation to disease and therapeutics. Biochem J 2020; 477:985-1008. [PMID: 32168372 DOI: 10.1042/bcj20190468] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/19/2020] [Accepted: 02/26/2020] [Indexed: 12/20/2022]
Abstract
Fatty acids (FAs) are stored safely in the form of triacylglycerol (TAG) in lipid droplet (LD) organelles by professional storage cells called adipocytes. These lipids are mobilized during adipocyte lipolysis, the fundamental process of hydrolyzing TAG to FAs for internal or systemic energy use. Our understanding of adipocyte lipolysis has greatly increased over the past 50 years from a basic enzymatic process to a dynamic regulatory one, involving the assembly and disassembly of protein complexes on the surface of LDs. These dynamic interactions are regulated by hormonal signals such as catecholamines and insulin which have opposing effects on lipolysis. Upon stimulation, patatin-like phospholipase domain containing 2 (PNPLA2)/adipocyte triglyceride lipase (ATGL), the rate limiting enzyme for TAG hydrolysis, is activated by the interaction with its co-activator, alpha/beta hydrolase domain-containing protein 5 (ABHD5), which is normally bound to perilipin 1 (PLIN1). Recently identified negative regulators of lipolysis include G0/G1 switch gene 2 (G0S2) and PNPLA3 which interact with PNPLA2 and ABHD5, respectively. This review focuses on the dynamic protein-protein interactions involved in lipolysis and discusses some of the emerging concepts in the control of lipolysis that include allosteric regulation and protein turnover. Furthermore, recent research demonstrates that many of the proteins involved in adipocyte lipolysis are multifunctional enzymes and that lipolysis can mediate homeostatic metabolic signals at both the cellular and whole-body level to promote inter-organ communication. Finally, adipocyte lipolysis is involved in various diseases such as cancer, type 2 diabetes and fatty liver disease, and targeting adipocyte lipolysis is of therapeutic interest.
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11
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Cheng J, Song Q, Yang Y, Sun Z, Tian X, Tian X, Feng L. Lipolysis by downregulating miR-92a activates the Wnt/β-catenin signaling pathway in hypoxic rats. Biomed Rep 2020; 13:33. [PMID: 32793347 PMCID: PMC7418506 DOI: 10.3892/br.2020.1340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/03/2020] [Indexed: 11/30/2022] Open
Abstract
The aim of the present study was to investigate the role of miR-92a in lipid metabolism in hypoxic rats. Microarray analysis and reverse transcription-quantitative (RT-q)PCR were used to detect changes in the mRNA expression levels of miR-92a in the epididymal fat of hypoxic and normoxic rats. The downstream target mRNA of miR-92a was predicted using bioinformatics analysis and verified using a dual luciferase reporter assay. Changes in the expression of frizzled (Fzd)10 and c-Myc in the epididymal fat were detected using RT-qPCR and western blotting. Microarray analysis and RT-qPCR results showed that the expression of miR-92a was significantly lower in the fat tissues of the hypoxic rats compared with the normoxic rats. The results of the dual luciferase reporter assay showed that the target gene of miR-92a was Fzd10, which is an acceptor in the Wnt pathway. Fzd10 expression was upregulated in the hypoxic rats. The mRNA expression levels of c-Myc, which is located downstream of the Wnt pathway, was increased significantly. The increase in the mRNA and protein expression levels of Fzd10 and c-Myc may be associated with miR-92a downregulation. Downregulation of miR-92a in-turn may result in lipolysis through the regulation of the Wnt/β-catenin signaling pathway, and thus weight loss in the rats.
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Affiliation(s)
- Jingjing Cheng
- Department of Sports and Health, Shandong Sport University, Jinan, Shandong 250102, P.R. China
| | - Qipeng Song
- Department of Sports and Health, Shandong Sport University, Jinan, Shandong 250102, P.R. China
| | - Yingjie Yang
- Department of Sports and Health, Shandong Sport University, Jinan, Shandong 250102, P.R. China
| | - Zhiyuan Sun
- Department of Sports and Health, Shandong Sport University, Jinan, Shandong 250102, P.R. China
| | - Xiaoyi Tian
- Department of Sports and Health, Shandong Sport University, Jinan, Shandong 250102, P.R. China
| | - Xuewen Tian
- Department of Sports and Health, Shandong Sport University, Jinan, Shandong 250102, P.R. China.,Biology Center, China Institute of Sport Science, Beijing 100061, P.R. China
| | - Lianshi Feng
- Biology Center, China Institute of Sport Science, Beijing 100061, P.R. China
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12
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de la Rosa Rodriguez MA, Kersten S. Regulation of lipid droplet homeostasis by hypoxia inducible lipid droplet associated HILPDA. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158738. [PMID: 32417386 DOI: 10.1016/j.bbalip.2020.158738] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/17/2020] [Accepted: 05/06/2020] [Indexed: 12/28/2022]
Abstract
Nearly all cell types have the ability to store excess energy as triglycerides in specialized organelles called lipid droplets. The formation and degradation of lipid droplets is governed by a diverse set of enzymes and lipid droplet-associated proteins. One of the lipid droplet-associated proteins is Hypoxia Inducible Lipid Droplet Associated (HILPDA). HILPDA was originally discovered in a screen to identify novel hypoxia-inducible proteins. Apart from hypoxia, levels of HILPDA are induced by fatty acids and adrenergic agonists. HILPDA is a small protein of 63 amino acids in humans and 64 amino acids in mice. Inside cells, HILPDA is located in the endoplasmic reticulum and around lipid droplets. Gain- and loss-of-function experiments have demonstrated that HILPDA promotes lipid storage in hepatocytes, macrophages and cancer cells. HILPDA increases lipid droplet accumulation at least partly by inhibiting triglyceride hydrolysis via ATGL and stimulating triglyceride synthesis via DGAT1. Overall, HILPDA is a novel regulatory signal that adjusts triglyceride storage and the intracellular availability of fatty acids to the external fatty acid supply and the capacity for oxidation.
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Affiliation(s)
- Montserrat A de la Rosa Rodriguez
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands.
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13
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Hofer P, Taschler U, Schreiber R, Kotzbeck P, Schoiswohl G. The Lipolysome-A Highly Complex and Dynamic Protein Network Orchestrating Cytoplasmic Triacylglycerol Degradation. Metabolites 2020; 10:E147. [PMID: 32290093 PMCID: PMC7240967 DOI: 10.3390/metabo10040147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 12/25/2022] Open
Abstract
The catabolism of intracellular triacylglycerols (TAGs) involves the activity of cytoplasmic and lysosomal enzymes. Cytoplasmic TAG hydrolysis, commonly termed lipolysis, is catalyzed by the sequential action of three major hydrolases, namely adipose triglyceride lipase, hormone-sensitive lipase, and monoacylglycerol lipase. All three enzymes interact with numerous protein binding partners that modulate their activity, cellular localization, or stability. Deficiencies of these auxiliary proteins can lead to derangements in neutral lipid metabolism and energy homeostasis. In this review, we summarize the composition and the dynamics of the complex lipolytic machinery we like to call "lipolysome".
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Affiliation(s)
- Peter Hofer
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Petra Kotzbeck
- Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria;
| | - Gabriele Schoiswohl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
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14
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Kulminskaya N, Oberer M. Protein-protein interactions regulate the activity of Adipose Triglyceride Lipase in intracellular lipolysis. Biochimie 2020; 169:62-68. [DOI: 10.1016/j.biochi.2019.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/06/2019] [Indexed: 12/31/2022]
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15
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VandeKopple MJ, Wu J, Auer EN, Giaccia AJ, Denko NC, Papandreou I. HILPDA Regulates Lipid Metabolism, Lipid Droplet Abundance, and Response to Microenvironmental Stress in Solid Tumors. Mol Cancer Res 2019; 17:2089-2101. [PMID: 31308147 DOI: 10.1158/1541-7786.mcr-18-1343] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/24/2019] [Accepted: 07/10/2019] [Indexed: 01/05/2023]
Abstract
Accumulation of lipid droplets has been observed in an increasing range of tumors. However, the molecular determinants of this phenotype and the impact of the tumor microenvironment on lipid droplet dynamics are not well defined. The hypoxia-inducible and lipid droplet associated protein HILPDA is known to regulate lipid storage and physiologic responses to feeding conditions in mice, and was recently shown to promote hypoxic lipid droplet formation through inhibition of the rate-limiting lipase adipose triglyceride lipase (ATGL). Here, we identify fatty acid loading and nutrient deprivation-induced autophagy as stimuli of HILPDA-dependent lipid droplet growth. Using mouse embryonic fibroblasts and human tumor cells, we found that genetic ablation of HILPDA compromised hypoxia-fatty acid- and starvation-induced lipid droplet formation and triglyceride storage. Nutrient deprivation upregulated HILPDA protein posttranscriptionally by a mechanism requiring autophagic flux and lipid droplet turnover, independent of HIF1 transactivation. Mechanistically, loss of HILPDA led to elevated lipolysis, which could be corrected by inhibition of ATGL. Lipidomic analysis revealed not only quantitative but also qualitative differences in the glycerolipid and phospholipid profile of HILPDA wild-type and knockout cells, indicating additional HILPDA functions affecting lipid metabolism. Deletion studies of HILPDA mutants identified the N-terminal hydrophobic domain as sufficient for targeting to lipid droplets and restoration of triglyceride storage. In vivo, HILPDA-ablated cells showed decreased intratumoral triglyceride levels and impaired xenograft tumor growth associated with elevated levels of apoptosis. IMPLICATIONS: Tumor microenvironmental stresses induce changes in lipid droplet dynamics via HILPDA. Regulation of triglyceride hydrolysis is crucial for cell homeostasis and tumor growth.
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Affiliation(s)
- Matthew J VandeKopple
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Jinghai Wu
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Erich N Auer
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Amato J Giaccia
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Nicholas C Denko
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Ioanna Papandreou
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio.
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16
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Cui C, Fu K, Yang L, Wu S, Cen Z, Meng X, Huang Q, Xie Z. Hypoxia-inducible gene 2 promotes the immune escape of hepatocellular carcinoma from nature killer cells through the interleukin-10-STAT3 signaling pathway. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:229. [PMID: 31142329 PMCID: PMC6542136 DOI: 10.1186/s13046-019-1233-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/15/2019] [Indexed: 01/07/2023]
Abstract
Background The study examines the expression and function of hypoxia-inducible gene 2 (HIG2) in hepatocellular carcinoma (HCC) tissues and cells. Methods Forty patients with HCC were included in the study. Bioinformatic analysis was used to analyze the clinical relevance of HIG2 expression in HCC tissue samples. Immunohistochemistry was employed to determine the expression of target proteins in tumor tissues. Hepatic HepG2 and SMMC-7721 cells were transfected with HIG2-targeting siRNA with Lipofectamine 2000. qRT-PCR was carried out to determine gene expression levels, while Western blotting was used to determine protein expression. A CCK-8 assay was performed to detect proliferation of cells, while migration and invasion of cells were studied by Transwell assay. Flow cytometry was carried out to detect surface markers and effector molecules in Nature killercells, as well as the killing effect of NK cells. Results HIG2 expression was upregulated in HCC. Silencing of HIG2 suppressed HCC cell migration and invasion. The killing effect of NK cells on HCC cells was enhanced after HIG2 was silenced in HCC cells. Conditioned media from HIG2-silenced SMMC-7721 cells inhibited the phenotype and function of NK cells. HCC cells with silenced expression of HIG2 modulated the activity of NK cells via STAT3. HIG2 promoted the evasion of HCC cells from killing by NK cells through upregulation of IL-10 expression. Conclusion The study demonstrates that HIG2 activates the STAT3 signaling pathway in NK cells by promoting IL-10 release by HCC cells, thereby inhibiting the killing activity of NK cells, and subsequently promoting the recurrence and metastasis of HCC.
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Affiliation(s)
- Chuanbao Cui
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China
| | - Kaiwen Fu
- Department of Pathology, Chongqing University Cancer Hospital, Chongqing, People's Republic of China
| | - Lu Yang
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China
| | - Shuzhi Wu
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China
| | - Zuojie Cen
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China
| | - Xingxing Meng
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China
| | - Qiongguang Huang
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China
| | - Zhichun Xie
- Department of Epidemiology, Guangxi Medical University, No. 22 Shuangyong Road, Nanning, 530021, Guangxi Zhuang Autonomous Region, People's Republic of China.
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17
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Padmanabha Das KM, Wechselberger L, Liziczai M, De la Rosa Rodriguez M, Grabner GF, Heier C, Viertlmayr R, Radler C, Lichtenegger J, Zimmermann R, Borst JW, Zechner R, Kersten S, Oberer M. Hypoxia-inducible lipid droplet-associated protein inhibits adipose triglyceride lipase. J Lipid Res 2018; 59:531-541. [PMID: 29326160 PMCID: PMC5832925 DOI: 10.1194/jlr.m082388] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/10/2018] [Indexed: 11/29/2022] Open
Abstract
Elaborate control mechanisms of intracellular triacylglycerol (TAG) breakdown are critically involved in the maintenance of energy homeostasis. Hypoxia-inducible lipid droplet-associated protein (HILPDA)/hypoxia-inducible gene-2 (Hig-2) has been shown to affect intracellular TAG levels, yet, the underlying molecular mechanisms are unclear. Here, we show that HILPDA inhibits adipose triglyceride lipase (ATGL), the enzyme catalyzing the first step of intracellular TAG hydrolysis. HILPDA shares structural similarity with G0/G1 switch gene 2 (G0S2), an established inhibitor of ATGL. HILPDA inhibits ATGL activity in a dose-dependent manner with an IC50 value of ∼2 μM. ATGL inhibition depends on the direct physical interaction of both proteins and involves the N-terminal hydrophobic region of HILPDA and the N-terminal patatin domain-containing segment of ATGL. Finally, confocal microscopy combined with Förster resonance energy transfer-fluorescence lifetime imaging microscopy analysis indicated that HILPDA and ATGL colocalize and physically interact intracellularly. These findings provide a rational biochemical explanation for the tissue-specific increased TAG accumulation in HILPDA-overexpressing transgenic mouse models.
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Affiliation(s)
| | - Lisa Wechselberger
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Márton Liziczai
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | | | - Gernot F Grabner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Christoph Heier
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Roland Viertlmayr
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Claudia Radler
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Jörg Lichtenegger
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Robert Zimmermann
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.,BioTechMed-Graz, 8010 Graz, Austria
| | - Jan Willem Borst
- Laboratory of Biochemistry and Microspectroscopy Research Facility, Wageningen University, Wageningen, The Netherlands
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.,BioTechMed-Graz, 8010 Graz, Austria
| | - Sander Kersten
- Division of Human Nutrition University of Graz, 8010 Graz, Austria
| | - Monika Oberer
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria .,BioTechMed-Graz, 8010 Graz, Austria
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18
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Zhang X, Saarinen AM, Hitosugi T, Wang Z, Wang L, Ho TH, Liu J. Inhibition of intracellular lipolysis promotes human cancer cell adaptation to hypoxia. eLife 2017; 6:31132. [PMID: 29256392 PMCID: PMC5739538 DOI: 10.7554/elife.31132] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 12/02/2017] [Indexed: 12/16/2022] Open
Abstract
Tumor tissues are chronically exposed to hypoxia owing to aberrant vascularity. Lipid droplet (LD) accumulation is a hallmark of hypoxic cancer cells, yet how LDs form and function during hypoxia remains poorly understood. Herein, we report that in various cancer cells upon oxygen deprivation, HIF-1 activation down-modulates LD catabolism mediated by adipose triglyceride lipase (ATGL), the key enzyme for intracellular lipolysis. Proteomics and functional analyses identified hypoxia-inducible gene 2 (HIG2), a HIF-1 target, as a new inhibitor of ATGL. Knockout of HIG2 enhanced LD breakdown and fatty acid (FA) oxidation, leading to increased ROS production and apoptosis in hypoxic cancer cells as well as impaired growth of tumor xenografts. All of these effects were reversed by co-ablation of ATGL. Thus, by inhibiting ATGL, HIG2 acts downstream of HIF-1 to sequester FAs in LDs away from the mitochondrial pathways for oxidation and ROS generation, thereby sustaining cancer cell survival in hypoxia.
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Affiliation(s)
- Xiaodong Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic in Arizona, Scottsdale, United States
| | - Alicia M Saarinen
- Department of Biochemistry and Molecular Biology, Mayo Clinic in Arizona, Scottsdale, United States.,HEALth Program, Mayo Clinic in Arizona, Scottsdale, United States
| | - Taro Hitosugi
- Department of Pharmacology, Mayo Clinic, Rochester, United States
| | - Zhenghe Wang
- Department of Genetics and Genome Sciences, Case Medical Center, Case Western Reserve University, Cleveland, United States
| | - Liguo Wang
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, United States
| | - Thai H Ho
- Division of Hematology and Medical Oncology, Mayo Clinic in Arizona, Scottsdale, United States
| | - Jun Liu
- Department of Biochemistry and Molecular Biology, Mayo Clinic in Arizona, Scottsdale, United States.,HEALth Program, Mayo Clinic in Arizona, Scottsdale, United States.,Division of Endocrinology, Mayo Clinic in Arizona, Scottsdale, United States
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de la Rosa Rodriguez MA, Kersten S. Regulation of lipid droplet-associated proteins by peroxisome proliferator-activated receptors. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1212-1220. [DOI: 10.1016/j.bbalip.2017.07.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/13/2017] [Accepted: 07/14/2017] [Indexed: 12/24/2022]
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20
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VandeKopple MJ, Wu J, Baer LA, Bal NC, Maurya SK, Kalyanasundaram A, Periasamy M, Stanford KI, Giaccia AJ, Denko NC, Papandreou I. Stress-responsive HILPDA is necessary for thermoregulation during fasting. J Endocrinol 2017; 235:27-38. [PMID: 28739822 PMCID: PMC5567683 DOI: 10.1530/joe-17-0289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 07/24/2017] [Indexed: 02/02/2023]
Abstract
Hypoxia-inducible lipid droplet-associated protein (HILPDA) has been shown to localize to lipid droplets in nutrient-responsive cell types such as hepatocytes and adipocytes. However, its role in the control of whole-body homeostasis is not known. We sought to measure cell-intrinsic and systemic stress responses in a mouse strain harboring whole-body Hilpda deficiency. We generated a genetically engineered mouse model of whole-body HILPDA deficiency by replacing the coding Hilpda exon with luciferase. We subjected the knockout animals to environmental stresses and measured whole-animal metabolic and behavioral parameters. Brown adipocyte precursors were isolated and differentiated in vitro to quantify the impact of HILPDA ablation in lipid storage and mobilization in these cells. HILPDA-knockout animals are viable and fertile, but show reduced ambulatory activity and oxygen consumption at regular housing conditions. Acclimatization at thermoneutral conditions abolished the phenotypic differences observed at 22°C. When fasted, HILPDA KO mice are unable to maintain body temperature and become hypothermic at 22°C, without apparent abnormalities in blood chemistry parameters or tissue triglyceride content. HILPDA expression was upregulated during adipocyte differentiation and activation in vitro; however, it was not required for lipid droplet formation in brown adipocytes. We conclude that HILPDA is necessary for efficient fuel utilization suggesting a homeostatic role for Hilpda in sub-optimal environments.
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Affiliation(s)
| | - Jinghai Wu
- Department of Radiation OncologyThe Ohio State University, Columbus, Ohio, USA
| | - Lisa A Baer
- Dorothy M. Davis Heart and Lung Research InstituteDepartment of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio, USA
| | - Naresh C Bal
- Department of Physiology and Cell BiologyThe Ohio State University, Columbus, Ohio, USA
| | - Santosh K Maurya
- Department of Physiology and Cell BiologyThe Ohio State University, Columbus, Ohio, USA
| | | | - Muthu Periasamy
- Department of Physiology and Cell BiologyThe Ohio State University, Columbus, Ohio, USA
| | - Kristin I Stanford
- Dorothy M. Davis Heart and Lung Research InstituteDepartment of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio, USA
| | - Amato J Giaccia
- Department of Radiation OncologyStanford University, Stanford, CA, USA
| | - Nicholas C Denko
- Department of Radiation OncologyThe Ohio State University, Columbus, Ohio, USA
| | - Ioanna Papandreou
- Department of Radiation OncologyThe Ohio State University, Columbus, Ohio, USA
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