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Shan Y, Xie T, Sun Y, Lu Z, Topatana W, Juengpanich S, Chen T, Han Y, Cao J, Hu J, Li S, Cai X, Chen M. Lipid metabolism in tumor-infiltrating regulatory T cells: perspective to precision immunotherapy. Biomark Res 2024; 12:41. [PMID: 38644503 PMCID: PMC11034130 DOI: 10.1186/s40364-024-00588-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 04/04/2024] [Indexed: 04/23/2024] Open
Abstract
Regulatory T cells (Tregs) are essential to the negative regulation of the immune system, as they avoid excessive inflammation and mediate tumor development. The abundance of Tregs in tumor tissues suggests that Tregs may be eliminated or functionally inhibited to stimulate antitumor immunity. However, immunotherapy targeting Tregs has been severely hampered by autoimmune diseases due to the systemic elimination of Tregs. Recently, emerging studies have shown that metabolic regulation can specifically target tumor-infiltrating immune cells, and lipid accumulation in TME is associated with immunosuppression. Nevertheless, how Tregs actively regulate metabolic reprogramming to outcompete effector T cells (Teffs), and how lipid metabolic reprogramming contributes to the immunomodulatory capacity of Tregs have not been fully discussed. This review will discuss the physiological processes by which lipid accumulation confers a metabolic advantage to tumor-infiltrating Tregs (TI-Tregs) and amplifies their immunosuppressive functions. Furthermore, we will provide a summary of the driving effects of various metabolic regulators on the metabolic reprogramming of Tregs. Finally, we propose that targeting the lipid metabolism of TI-Tregs could be efficacious either alone or in conjunction with immune checkpoint therapy.
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Affiliation(s)
- Yukai Shan
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Tianao Xie
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Yuchao Sun
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Ziyi Lu
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Win Topatana
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
- School of Medicine, Zhejiang University, 310058, Hangzhou, China
| | - Sarun Juengpanich
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Tianen Chen
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Yina Han
- Department of Pathology, Sir Run-Run Shaw Hospital, Zhejiang University School of Medicine, 310016, Hangzhou, China
| | - Jiasheng Cao
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Jiahao Hu
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China
| | - Shijie Li
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China.
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China.
| | - Xiujun Cai
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China.
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China.
- School of Medicine, Zhejiang University, 310058, Hangzhou, China.
| | - Mingyu Chen
- Department of General Surgery, Sir Run-Run Shaw Hospital, Zhejiang University, Key Laboratory of Endoscopic Technique Research of Zhejiang Province, No.3 East Qingchun Road, 310016, Hangzhou, China.
- National Engineering Research Center of Innovation and Application of Minimally Invasive Instruments, Sir Run-Run Shaw Hospital, Zhejiang University, 310016, Hangzhou, China.
- School of Medicine, Zhejiang University, 310058, Hangzhou, China.
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Spaulding SC, Bollag WB. The role of lipid second messengers in aldosterone synthesis and secretion. J Lipid Res 2022; 63:100191. [PMID: 35278411 PMCID: PMC9020094 DOI: 10.1016/j.jlr.2022.100191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 11/23/2022] Open
Abstract
Second messengers are small rapidly diffusing molecules or ions that relay signals between receptors and effector proteins to produce a physiological effect. Lipid messengers constitute one of the four major classes of second messengers. The hydrolysis of two main classes of lipids, glycerophospholipids and sphingolipids, generate parallel profiles of lipid second messengers: phosphatidic acid (PA), diacylglycerol (DAG), and lysophosphatidic acid versus ceramide, ceramide-1-phosphate, sphingosine, and sphingosine-1-phosphate, respectively. In this review, we examine the mechanisms by which these lipid second messengers modulate aldosterone production at multiple levels. Aldosterone is a mineralocorticoid hormone responsible for maintaining fluid volume, electrolyte balance, and blood pressure homeostasis. Primary aldosteronism is a frequent endocrine cause of secondary hypertension. A thorough understanding of the signaling events regulating aldosterone biosynthesis may lead to the identification of novel therapeutic targets. The cumulative evidence in this literature emphasizes the critical roles of PA, DAG, and sphingolipid metabolites in aldosterone synthesis and secretion. However, it also highlights the gaps in our knowledge, such as the preference for phospholipase D-generated PA or DAG, as well as the need for further investigation to elucidate the precise mechanisms by which these lipid second messengers regulate optimal aldosterone production.
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Affiliation(s)
- Shinjini C Spaulding
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Wendy B Bollag
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, GA, USA; Research Department, Charlie Norwood VA Medical Center, Augusta, GA, USA.
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3
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Beyond Lipid Signaling: Pleiotropic Effects of Diacylglycerol Kinases in Cellular Signaling. Int J Mol Sci 2020; 21:ijms21186861. [PMID: 32962151 PMCID: PMC7554708 DOI: 10.3390/ijms21186861] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/11/2020] [Accepted: 09/16/2020] [Indexed: 12/13/2022] Open
Abstract
The diacylglycerol kinase family, which can attenuate diacylglycerol signaling and activate phosphatidic acid signaling, regulates various signaling transductions in the mammalian cells. Studies on the regulation of diacylglycerol and phosphatidic acid levels by various enzymes, the identification and characterization of various diacylglycerol and phosphatidic acid-regulated proteins, and the overlap of different diacylglycerol and phosphatidic acid metabolic and signaling processes have revealed the complex and non-redundant roles of diacylglycerol kinases in regulating multiple biochemical and biological networks. In this review article, we summarized recent progress in the complex and non-redundant roles of diacylglycerol kinases, which is expected to aid in restoring dysregulated biochemical and biological networks in various pathological conditions at the bed side.
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DGKα in Neutrophil Biology and Its Implications for Respiratory Diseases. Int J Mol Sci 2019; 20:ijms20225673. [PMID: 31766109 PMCID: PMC6887790 DOI: 10.3390/ijms20225673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 12/21/2022] Open
Abstract
Diacylglycerol kinases (DGKs) play a key role in phosphoinositide signaling by removing diacylglycerol and generating phosphatidic acid. Besides the well-documented role of DGKα and DGKζ as negative regulators of lymphocyte responses, a robust body of literature points to those enzymes, and specifically DGKα, as crucial regulators of leukocyte function. Upon neutrophil stimulation, DGKα activation is necessary for migration and a productive response. The role of DGKα in neutrophils is evidenced by its aberrant behavior in juvenile periodontitis patients, which express an inactive DGKα transcript. Together with in vitro experiments, this suggests that DGKs may represent potential therapeutic targets for disorders where inflammation, and neutrophils in particular, plays a major role. In this paper we focus on obstructive respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD), but also rare genetic diseases such as alpha-1-antitrypsin deficiency. Indeed, the biological role of DGKα is understudied outside the T lymphocyte field. The recent wave of research aiming to develop novel and specific inhibitors as well as KO mice will allow a better understanding of DGK's role in neutrophilic inflammation. Better knowledge and pharmacologic tools may also allow DGK to move from the laboratory bench to clinical trials.
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Shan L, Wang D, Mao Q, Xia H. Establishment of a DGKθ Endogenous Promoter Luciferase Reporter HepG2 Cell Line for Studying the Transcriptional Regulation of DGKθ Gene. Appl Biochem Biotechnol 2018; 187:1344-1355. [PMID: 30229432 DOI: 10.1007/s12010-018-2890-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 09/10/2018] [Indexed: 12/29/2022]
Abstract
DGKθ protein expression levels are closely related to the development of diseases including diabetes, cancer, and neuronal disease. To investigate the transcriptional regulation of the DGKθ gene, we used CRISPR/Cas9 to generate a DGKθ endogenous promoter luciferase reporter HepG2 cell line, in which the endogenous DGKθ promoter controls the expression of the luciferase reporter gene. To test the cell line, FXR, the transcription factor for upregulating the expression of DGKθ gene, was used to validate the cell line. Furthermore, the reported agonists for the expression of DGKθ, cAMP and GW4064, the known inhibitor for DGKθ enzyme activity, R59949, and a potential regulator for DGKθ enzyme expression, EGCG (the major catechin in green tea), were applied to the reporter cell line. The results indicated that these reagents could significantly regulate the expression of reporter luciferase. Finally, four transcription factors (E2F1, c-Myc, USF1, and Bmal1) potentially binding to the DGKθ gene's upstream promoter region were tested. DGKθ expression was upregulated by c-Myc and downregulated by E2F1, which was also confirmed in wild-type HepG2 cells. We found that the cell line's luciferase activity was directly correlated with DGKθ endogenous promoter activity, suggesting that it is liable and sensitive for studying DGKθ transcriptional regulation. The study provides a useful tool for high-throughput drug screening for the treatment of DGKθ-involved diseases.
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Affiliation(s)
- Linlin Shan
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, People's Republic of China
| | - Dongyang Wang
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, People's Republic of China
| | - Qinwen Mao
- Department of Pathology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Ward 3-140, Chicago, IL, 60611, USA
| | - Haibin Xia
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, People's Republic of China.
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Zhang J, Zhao J, Zheng X, Cai K, Mao Q, Xia H. Establishment of a novel hepatic steatosis cell model by Cas9/sgRNA-mediated DGKθ gene knockout. Mol Med Rep 2018; 17:2169-2176. [PMID: 29207074 PMCID: PMC5783457 DOI: 10.3892/mmr.2017.8140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 08/04/2017] [Indexed: 01/31/2023] Open
Abstract
To investigate the role of diacylglycerol kinase θ (DGKθ) in lipid metabolism and insulin resistance, the present study generated an in vitro hepatic steatosis cell model by knockout of the DGKθ gene in liver cancer cell line HepG2 using CRISPR/Cas9 technology. The cell line was characterized by Oil Red O staining and shown to exhibit increased intracellular lipid accumulation, compared with that in wild‑type liver cancer cell line HepG2. The gene expression levels of signaling proteins in pathways involved in lipid metabolism, insulin resistance and gluconeogenesis were also examined. The DGKθ‑knockout HepG2 cells showed increased mRNA and protein expression levels of lipid synthesis‑related genes, fatty acid synthase, peroxisome proliferator‑activated receptor‑γ and sterol regulatory element‑binding protein‑1c, and decreased expression levels of the lipolysis‑related gene, carnitine palmitoyltransferase1A. These changes may account for the increased intracellular lipid content of this cell line. The DGKθ‑knockout HepG2 cells also exhibited an increased phosphorylation level of protein kinase Cε and decreased phosphorylation levels of insulin receptor substrate 1, mechanistic target of rapamycin and protein kinase B (also known as Akt). These changes have been reported to mediate insulin resistance. Taken together, an in vitro hepatic steatosis cell model was established in the present study, providing a valuable tool for understanding the pathogenesis of nonalcoholic fatty liver disease and associated insulin resistance, and for developing treatment strategies for this disease.
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Affiliation(s)
- Jingjing Zhang
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi 710062, P.R. China
| | - Junli Zhao
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi 710062, P.R. China
| | - Xiaojing Zheng
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi 710062, P.R. China
| | - Kai Cai
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi 710062, P.R. China
| | - Qinwen Mao
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Haibin Xia
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi 710062, P.R. China
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7
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Abstract
The present review aimed to assess the networks of transcription factors regulating the Oct4 expression in mice. Through a comprehensive analysis of the binding sites and the interrelationships of the transcription factors of Oct4, it is found that transcription factors of Oct4 form three regulating complexes centered by Oct4-Sox2, Nanog, and Lrh1. They bind on CR4, CR2, and CR1 regions of Oct4 promoter/enhancer, respectively, to activate Oct4 transcription synergistically. This article also discusses the mechanisms of fine-tuning the Oct4 expression. These findings have important implications in the field of stem cell and developmental biology.
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Affiliation(s)
- Yu-Qiang Li
- Marine College, Shandong University (Weihai) , Weihai, China
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8
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Tu-Sekine B, Goldschmidt HL, Raben DM. DGK-θ: Structure, Enzymology, and Physiological Roles. Front Cell Dev Biol 2016; 4:101. [PMID: 27683659 PMCID: PMC5021689 DOI: 10.3389/fcell.2016.00101] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/29/2016] [Indexed: 12/13/2022] Open
Abstract
Diacylglycerol kinases (DGKs) are a family of enzymes that catalyze the ATP-dependent phosphorylation of diacylglycerol (DAG) to phosphatidic acid (PtdOH). The recognition of the importance of these enzymes has been increasing ever since it was determined that they played a role in the phosphatidylinositol (PtdIns) cycle and a number of excellent reviews have already been written [(see van Blitterswijk and Houssa, 2000; Kanoh et al., 2002; Mérida et al., 2008; Tu-Sekine and Raben, 2009, 2011; Shulga et al., 2011; Tu-Sekine et al., 2013) among others]. We now know there are ten mammalian DGKs that are organized into five classes. DGK-θ is the lone member of the Type V class of DGKs and remains as one of the least studied. This review focuses on our current understanding of the structure, enzymology, regulation, and physiological roles of this DGK and suggests some future areas of research to understand this DGK isoform.
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Affiliation(s)
- Becky Tu-Sekine
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Hana L Goldschmidt
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Daniel M Raben
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine Baltimore, MD, USA
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Zhang P, Verity MA, Reue K. Lipin-1 regulates autophagy clearance and intersects with statin drug effects in skeletal muscle. Cell Metab 2014; 20:267-79. [PMID: 24930972 PMCID: PMC4170588 DOI: 10.1016/j.cmet.2014.05.003] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/03/2014] [Accepted: 04/21/2014] [Indexed: 02/04/2023]
Abstract
LPIN1 encodes lipin-1, a phosphatidic acid phosphatase (PAP) enzyme that catalyzes the dephosphorylation of phosphatidic acid to form diacylglycerol. Homozygous LPIN1 gene mutations cause severe rhabdomyolysis, and heterozygous LPIN1 missense mutations may promote statin-induced myopathy. We demonstrate that lipin-1-related myopathy in the mouse is associated with a blockade in autophagic flux and accumulation of aberrant mitochondria. Lipin-1 PAP activity is required for maturation of autolysosomes, through its activation of the protein kinase D (PKD)-Vps34 phosphatidylinositol 3-kinase signaling cascade. Statin treatment also reduces PKD activation and autophagic flux, which are compounded by diminished mammalian target of rapamycin (mTOR) abundance in lipin-1-haploinsufficent and -deficient muscle. Lipin-1 restoration in skeletal muscle prevents myonecrosis and statin toxicity in vivo, and activated PKD rescues autophagic flux in lipin-1-deficient cells. Our findings identify lipin-1 PAP activity as a component of the macroautophagy pathway and define the basis for lipin-1-related myopathies.
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Affiliation(s)
- Peixiang Zhang
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - M Anthony Verity
- Division of Neuropathology, Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Karen Reue
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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10
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Blind RD. Disentangling biological signaling networks by dynamic coupling of signaling lipids to modifying enzymes. Adv Biol Regul 2014; 54:25-38. [PMID: 24176936 PMCID: PMC3946453 DOI: 10.1016/j.jbior.2013.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 09/08/2013] [Accepted: 09/09/2013] [Indexed: 06/02/2023]
Abstract
An unresolved problem in biological signal transduction is how particular branches of highly interconnected signaling networks can be decoupled, allowing activation of specific circuits within complex signaling architectures. Although signaling dynamics and spatiotemporal mechanisms serve critical roles, it remains unclear if these are the only ways cells achieve specificity within networks. The transcription factor Steroidogenic Factor-1 (SF-1) is an excellent model to address this question, as it forms dynamic complexes with several chemically distinct lipid species (phosphatidylinositols, phosphatidylcholines and sphingolipids). This property is important since lipids bound to SF-1 are modified by lipid signaling enzymes (IPMK & PTEN), regulating SF-1 biological activity in gene expression. Thus, a particular SF-1/lipid complex can interface with a lipid signaling enzyme only if SF-1 has been loaded with a chemically compatible lipid substrate. This mechanism permits dynamic downstream responsiveness to constant upstream input, disentangling specific pathways from the full network. The potential of this paradigm to apply generally to nuclear lipid signaling is discussed, with particular attention given to the nuclear receptor superfamily of transcription factors and their phospholipid ligands.
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Affiliation(s)
- Raymond D Blind
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA.
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11
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Cai K, Lucki NC, Sewer MB. Silencing diacylglycerol kinase-theta expression reduces steroid hormone biosynthesis and cholesterol metabolism in human adrenocortical cells. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:552-62. [PMID: 24369117 DOI: 10.1016/j.bbalip.2013.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 12/10/2013] [Accepted: 12/13/2013] [Indexed: 11/29/2022]
Abstract
Diacylglycerol kinase theta (DGKθ) plays a pivotal role in regulating adrenocortical steroidogenesis by synthesizing the ligand for the nuclear receptor steroidogenic factor 1 (SF1). In response to activation of the cAMP signaling cascade nuclear DGK activity is rapidly increased, facilitating PA-mediated, SF1-dependent transcription of genes required for cortisol and dehydroepiandrosterone (DHEA) biosynthesis. Based on our previous work identifying DGKθ as the enzyme that produces the agonist for SF1, we generated a tetracycline-inducible H295R stable cell line to express a short hairpin RNA (shRNA) against DGKθ and characterized the effect of silencing DGKθ on adrenocortical gene expression. Genome-wide DNA microarray analysis revealed that silencing DGKθ expression alters the expression of multiple genes, including steroidogenic genes, nuclear receptors and genes involved in sphingolipid, phospholipid and cholesterol metabolism. Interestingly, the expression of sterol regulatory element binding proteins (SREBPs) was also suppressed. Consistent with the suppression of SREBPs, we observed a down-regulation of multiple SREBP target genes, including 3-hydroxy-3-methylglutary coenzyme A reductase (HMG-CoA red) and CYP51, concomitant with a decrease in cellular cholesterol. DGKθ knockdown cells exhibited a reduced capacity to metabolize PA, with a down-regulation of lipin and phospholipase D (PLD) isoforms. In contrast, suppression of DGKθ increased the expression of several genes in the sphingolipid metabolic pathway, including acid ceramidase (ASAH1) and sphingosine kinases (SPHK). In summary, these data demonstrate that DGKθ plays an important role in steroid hormone production in human adrenocortical cells.
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Affiliation(s)
- Kai Cai
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
| | - Natasha C Lucki
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
| | - Marion B Sewer
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA.
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12
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Wang CM, Liu R, Wang L, Yang WH. Acidic residue Glu199 increases SUMOylation level of nuclear hormone receptor NR5A1. Int J Mol Sci 2013; 14:22331-45. [PMID: 24232453 PMCID: PMC3856066 DOI: 10.3390/ijms141122331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 11/01/2013] [Accepted: 11/05/2013] [Indexed: 01/29/2023] Open
Abstract
Steroidogenic factor 1 (NR5A1/SF1) is a well-known master regulator in controlling adrenal and sexual development, as well as regulating numerous genes involved in adrenal and gonadal steroidogenesis. Several studies including ours have demonstrated that NR5A1 can be SUMOylated on lysine 194 (K194, the major site) and lysine 119 (K119, the minor site), and the cycle of SUMOylation regulates NR5A1’s transcriptional activity. An extended consensus negatively charged amino acid-dependent SUMOylation motif (NDSM) enhances the specificity of substrate modification by SUMO has been reported; however, the mechanism of NDSM for NR5A1 remains to be clarified. In this study, we investigated the functional significance of the acidic residue located downstream from the core consensus SUMO site of NR5A1. Here we report that E199A (glutamic acid was replaced with alanine) of NR5A1 reduced, but not completely abolished, its SUMOylation level. We next characterized the functional role of NR5A1 E199A on target gene expression and protein levels. We found that E199A alone, as well as combination with K194R, increased Mc2r and Cyp19a1 reporter activities. Moreover, E199A alone as well as combination with K194R enhanced NR5A1-mediated STAR protein levels in mouse adrenocortical cancer Y1 cells. We also observed that E199A increased interaction of NR5A1 with CDK7 and SRC1. Overall, we provide the evidence that the acidic residue (E199) located downstream from the core consensus SUMO site of NR5A1 is, at least in part, required for SUMOylation of NR5A1 and for its mediated target gene and protein expression.
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Affiliation(s)
- Chiung-Min Wang
- Department of Biomedical Sciences, Mercer University School of Medicine, Savannah, GA 31404, USA; E-Mail:
| | - Runhua Liu
- Department of Genetics and Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA; E-Mails: (R.L.); (L.W.)
| | - Lizhong Wang
- Department of Genetics and Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA; E-Mails: (R.L.); (L.W.)
| | - Wei-Hsiung Yang
- Department of Biomedical Sciences, Mercer University School of Medicine, Savannah, GA 31404, USA; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-912-350-1708; Fax: +1-912-350-1765
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13
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Diacylglycerol kinase θ couples farnesoid X receptor-dependent bile acid signalling to Akt activation and glucose homoeostasis in hepatocytes. Biochem J 2013; 454:267-74. [PMID: 23767959 DOI: 10.1042/bj20130609] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
DGKs (diacylglycerol kinases) catalyse the conversion of diacylglycerol into PA (phosphatidic acid), a positive modulator of mTOR (mammalian target of rapamycin). We have found that chenodeoxycholic acid and the synthetic FXR (farnesoid X receptor) ligand GW4064 induce the mRNA and protein expression of DGKθ in the HepG2 cell line and in primary human hepatocytes. Reporter gene studies using 1.5 kB of the DGKθ promoter fused to the luciferase gene revealed that bile acids increase DGKθ transcriptional activity. Mutation of putative FXR-binding sites attenuated the ability of GW4046 to increase DGKθ luciferase activity. Consistent with this finding, ChIP (chromatin immunoprecipitation) assays demonstrated that bile acid signalling increased the recruitment of FXR to the DGKθ promoter. Furthermore, GW4064 evoked a time-dependent increase in the cellular concentration of PA. We also found that GW4064 and PA promote the phosphorylation of mTOR, Akt and FoxO1 (forkhead box O1), and that silencing DGKθ expression significantly abrogated the ability of GW4046 to promote the phosphorylation of these PA-regulated targets. DGKθ was also required for bile-acid-dependent decreased glucose production. Taken together, our results establish DGKθ as a key mediator of bile-acid-stimulated modulation of mTORC2 (mTOR complex 2), the Akt pathway and glucose homoeostasis.
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