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Lu Y, Ma WB, Ren GM, Li YT, Wang T, Zhan YQ, Xiang SS, Chen H, Gao HY, Zhao K, Yu M, Li CY, Yang XM, Yin RH. GPS2 promotes erythroid differentiation in K562 erythroleukemia cells primarily via NCOR1. Int J Hematol 2024:10.1007/s12185-024-03797-x. [PMID: 38814500 DOI: 10.1007/s12185-024-03797-x] [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: 11/22/2023] [Revised: 05/10/2024] [Accepted: 05/20/2024] [Indexed: 05/31/2024]
Abstract
G protein pathway suppressor 2 (GPS2) has been shown to play a pivotal role in human and mouse definitive erythropoiesis in an EKLF-dependent manner. However, whether GPS2 affects human primitive erythropoiesis is still unknown. This study demonstrated that GPS2 positively regulates erythroid differentiation in K562 cells, which have a primitive erythroid phenotype. Overexpression of GPS2 promoted hemin-induced hemoglobin synthesis in K562 cells as assessed by the increased percentage of benzidine-positive cells and the deeper red coloration of the cell pellets. In contrast, knockdown of GPS2 inhibited hemin-induced erythroid differentiation of K562 cells. GPS2 overexpression also enhanced erythroid differentiation of K562 cells induced by cytosine arabinoside (Ara-C). GPS2 induced hemoglobin synthesis by increasing the expression of globin and ALAS2 genes, either under steady state or upon hemin treatment. Promotion of erythroid differentiation of K562 cells by GPS2 mainly relies on NCOR1, as knockdown of NCOR1 or lack of the NCOR1-binding domain of GPS2 potently diminished the promotive effect. Thus, our study revealed a previously unknown role of GPS2 in regulating human primitive erythropoiesis in K562 cells.
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Affiliation(s)
- Ying Lu
- College of Life Science and Bioengineering, Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, 100124, China
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Wen-Bing Ma
- Institute of Health Service and Transfusion Medicine, Beijing, 100850, China
| | - Guang-Ming Ren
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Ya-Ting Li
- College of Life Science and Bioengineering, Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, 100124, China
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Ting Wang
- College of Life Science and Bioengineering, Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, 100124, China
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Yi-Qun Zhan
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Shen-Si Xiang
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Hui Chen
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Hui-Ying Gao
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Ke Zhao
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Miao Yu
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Chang-Yan Li
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Xiao-Ming Yang
- College of Life Science and Bioengineering, Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, 100124, China.
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China.
| | - Rong-Hua Yin
- State Key Laboratory of Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Radiation Medicine, Beijing, 100850, China.
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Grigorova N, Ivanova Z, Vachkova E, Petrova V, Penev T. DHA-Provoked Reduction in Adipogenesis and Glucose Uptake Could Be Mediated by Gps2 Upregulation in Immature 3T3-L1 Cells. Int J Mol Sci 2023; 24:13325. [PMID: 37686130 PMCID: PMC10487817 DOI: 10.3390/ijms241713325] [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: 08/04/2023] [Revised: 08/24/2023] [Accepted: 08/26/2023] [Indexed: 09/10/2023] Open
Abstract
The signaling pathway of fatty acids in the context of obesity is an extensively explored topic, yet their primary mechanism of action remains incompletely understood. This study aims to examine the effect of docosahexaenoic acid (DHA) on some crucial aspects of adipogenesis in differentiating 3T3-L1 cells, using palmitic acid-treated (PA), standard differentiated, and undifferentiated adipocytes as controls. Employing 60 µM DHA or PA, 3T3-L1 preadipocytes were treated from the onset of adipogenesis, with negative and positive controls included. After eight days, we performed microscopic observations, cell viability assays, the determination of adiponectin concentration, intracellular lipid accumulation, and gene expression analysis. Our findings demonstrated that DHA inhibits adipogenesis, lipolysis, and glucose uptake by suppressing peroxisome proliferator-activated receptor gamma (Pparg) and G-protein coupled receptor 120 (Gpr120) gene expression. Cell cytotoxicity was ruled out as a causative factor, and β-oxidation involvement was suspected. These results challenge the conventional belief that omega-3 fatty acids, acting as Pparg and Gpr120 agonists, promote adipogenesis and enhance insulin-dependent glucose cell flux. Moreover, we propose a novel hypothesis suggesting the key role of the co-repressor G protein pathway suppressor 2 in mediating this process. Additional investigations are required to elucidate the molecular mechanisms driving DHA's anti-adipogenic effect and its broader health implications.
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Affiliation(s)
- Natalia Grigorova
- Department of Pharmacology, Animal Physiology, Biochemistry and Chemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria; (Z.I.); (E.V.); (V.P.)
| | - Zhenya Ivanova
- Department of Pharmacology, Animal Physiology, Biochemistry and Chemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria; (Z.I.); (E.V.); (V.P.)
| | - Ekaterina Vachkova
- Department of Pharmacology, Animal Physiology, Biochemistry and Chemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria; (Z.I.); (E.V.); (V.P.)
| | - Valeria Petrova
- Department of Pharmacology, Animal Physiology, Biochemistry and Chemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria; (Z.I.); (E.V.); (V.P.)
| | - Toncho Penev
- Department of Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria;
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English J, Orofino J, Cederquist CT, Paul I, Li H, Auwerx J, Emili A, Belkina A, Cardamone D, Perissi V. GPS2-mediated regulation of the adipocyte secretome modulates adipose tissue remodeling at the onset of diet-induced obesity. Mol Metab 2023; 69:101682. [PMID: 36731652 PMCID: PMC9922684 DOI: 10.1016/j.molmet.2023.101682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 01/22/2023] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE Dysfunctional, unhealthy expansion of white adipose tissue due to excess dietary intake is a process at the root of obesity and Type 2 Diabetes development. The objective of this study is to contribute to a better understanding of the underlying mechanism(s) regulating the early stages of adipose tissue expansion and adaptation to dietary stress due to an acute, high-fat diet (HFD) challenge, with a focus on the communication between adipocytes and other stromal cells. METHODS We profiled the early response to high-fat diet exposure in wildtype and adipocyte-specific GPS2-KO (GPS2-AKO) mice at the cellular, tissue and organismal level. A multi-pronged approach was employed to disentangle the complex cellular interactions dictating tissue remodeling, via single-cell RNA sequencing and FACS profiling of the stromal fraction, and semi-quantitative proteomics of the adipocyte-derived exosomal cargo after 5 weeks of HFD feeding. RESULTS Our results indicate that loss of GPS2 in mature adipocytes leads to impaired adaptation to the metabolic stress imposed by HFD feeding. GPS2-AKO mice are significantly more inflamed, insulin resistant, and obese, compared to the WT counterparts. At the cellular level, lack of GPS2 in adipocytes impacts upon other stromal populations, with both the eWAT and scWAT depots exhibiting changes in the immune and non-immune compartments that contribute to an increase in inflammatory and anti-adipogenic cell types. Our studies also revealed that adipocyte to stromal cell communication is facilitated by exosomes, and that transcriptional rewiring of the exosomal cargo is crucial for tissue remodeling. Loss of GPS2 results in increased expression of secreted factors promoting a TGFβ-driven fibrotic microenvironment favoring unhealthy tissue remodeling and expansion. CONCLUSIONS Adipocytes serve as an intercellular signaling hub, communicating with the stromal compartment via paracrine signaling. Our study highlights the importance of proper regulation of the 'secretome' released by energetically stressed adipocytes at the onset of obesity. Altered transcriptional regulation of factors secreted via adipocyte-derived exosomes (AdExos), in the absence of GPS2, contributes to the establishment of an anti-adipogenic, pro-fibrotic adipose tissue environment, and to hastened progression towards a metabolically dysfunctional phenotype.
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Affiliation(s)
- Justin English
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA.
| | - Joseph Orofino
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
| | - Carly T. Cederquist
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Indranil Paul
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; Center for Network Systems Biology, Boston University, Boston, MA, USA.
| | - Hao Li
- Laboratory of Integrative Systems Physiology, Interfaculty Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland.
| | - Johan Auwerx
- Laboratory of Integrative Systems Physiology, Interfaculty Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland.
| | - Andrew Emili
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; Center for Network Systems Biology, Boston University, Boston, MA, USA.
| | - Anna Belkina
- Flow Cytometry Core Facility, Boston University School of Medicine, Boston, MA, USA; Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA.
| | - Dafne Cardamone
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
| | - Valentina Perissi
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; School of Life Science, Northwestern Polytechnical University, Xi'an 710072, China.
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Lau KH, Waldhart AN, Dykstra H, Avequin T, Wu N. PPARγ and C/EBPα response to acute cold stress in brown adipose tissue. iScience 2022; 26:105848. [PMID: 36624847 PMCID: PMC9823219 DOI: 10.1016/j.isci.2022.105848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/14/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Brown adipose tissue (BAT) has the ability to burn calories as heat. Utilizing BAT thermogenesis is thus an attractive way to combat obesity. However, the transcriptional network resulting in the lipid synthesis to oxidation shift during thermogenesis is not completely understood. Here, we report the regulation of two master regulators of adipogenesis, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα), during acute cold stress in BAT. We found PPARγ dissociates from DNA in a fifth of its binding sites and these include Cebpa enhancers, leading to decreased C/EBPα expression. This dissociation requires PPARγ binding to activating ligands and is thus modulated by diet. Meanwhile, PPARα also detaches from DNA, and co-activator PGC1α associates with ERRα as part of a transcriptional network regulating lipid metabolism. Subsequent global replacement of C/EBPα by C/EBPβ and its associated transcriptional machinery is required for upregulation of structural lipid synthesis despite general upregulation of fatty acid oxidation.
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Affiliation(s)
- Kin H. Lau
- Van Andel Institute, Grand Rapids, MI 49503, USA
| | | | | | | | - Ning Wu
- Van Andel Institute, Grand Rapids, MI 49503, USA,Corresponding author
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Interaction of NEP with G Protein Pathway Suppressor 2 Facilitates Influenza A Virus Replication by Weakening the Inhibition of GPS2 to RNA Synthesis and Ribonucleoprotein Assembly. J Virol 2021; 95:JVI.00008-21. [PMID: 33658351 PMCID: PMC8139649 DOI: 10.1128/jvi.00008-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The nuclear export protein (NEP) serves multiple functions in the life cycle of influenza A virus (IAV). Identifying novel host proteins that interact with NEP and understanding their functions in IAV replication are of great interest. In this study, we screened and confirmed the direct interaction of G protein pathway suppressor 2 (GPS2) with NEP through a yeast two-hybrid screening assay and glutathione S-transferase-pulldown and co-immunoprecipitation assays. Knockdown or knockout of GPS2 enhanced IAV titers, whereas overexpression of GPS2 impaired IAV replication, demonstrating that GPS2 acted as a negative host factor in IAV replication. Meanwhile, GPS2 inhibited viral RNA synthesis by reducing the assembly of IAV polymerase. Interestingly, IAV NEP interacted with GPS2 and mediated its nuclear export, thereby activated the degradation of GPS2. Thus, NEP-GPS2 interaction weakened the inhibition of GPS2 to viral polymerase activity and benefited virus replication. Overall, this study identified the novel NEP-binding host partner GPS2 as a critical host factor to participate in IAV replication. These findings provided novel insights into the interactions between IAV and host cells, revealing a new function for GPS2 during IAV replication.Importance: NEP is proposed to play multiple biologically important roles in the life cycle of IAV, which largely relies on host factors by interaction. Our study demonstrated that GPS2 could reduce the interaction between PB1 and PB2 and interfere with vRNP assembly. Thus, GPS2 inhibited the RNA synthesis of IAV and negatively regulated its replication. Importantly, IAV NEP interacted with GPS2 and mediated the nuclear export of GPS2, thereby activated the degradation of GPS2. Thus, NEP-GPS2 interaction weakened the inhibition of GPS2 to viral polymerase activity and benefited virus replication.
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6
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GPS2 promotes erythroid differentiation by control of the stability of EKLF protein. Blood 2021; 135:2302-2315. [PMID: 32384137 DOI: 10.1182/blood.2019003867] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/05/2020] [Indexed: 02/08/2023] Open
Abstract
Erythropoiesis is a complex multistage process that involves differentiation of early erythroid progenitors to enucleated mature red blood cells, in which lineage-specific transcription factors play essential roles. Erythroid Krüppel-like factor (EKLF/KLF1) is a pleiotropic erythroid transcription factor that is required for the proper maturation of the erythroid cells, whose expression and activation are tightly controlled in a temporal and differentiation stage-specific manner. Here, we uncover a novel role of G-protein pathway suppressor 2 (GPS2), a subunit of the nuclear receptor corepressor/silencing mediator of retinoic acid and thyroid hormone receptor corepressor complex, in erythrocyte differentiation. Our study demonstrates that knockdown of GPS2 significantly suppresses erythroid differentiation of human CD34+ cells cultured in vitro and xenotransplanted in nonobese diabetic/severe combined immunodeficiency/interleukin-2 receptor γ-chain null mice. Moreover, global deletion of GPS2 in mice causes impaired erythropoiesis in the fetal liver and leads to severe anemia. Flow cytometric analysis and Wright-Giemsa staining show a defective differentiation at late stages of erythropoiesis in Gps2-/- embryos. Mechanistically, GPS2 interacts with EKLF and prevents proteasome-mediated degradation of EKLF, thereby increasing EKLF stability and transcriptional activity. Moreover, we identify the amino acids 191-230 region in EKLF protein, responsible for GPS2 binding, that is highly conserved in mammals and essential for EKLF protein stability. Collectively, our study uncovers a previously unknown role of GPS2 as a posttranslational regulator that enhances the stability of EKLF protein and thereby promotes erythroid differentiation.
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7
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Dias MMG, Batista FAH, Tittanegro TH, de Oliveira AG, Le Maire A, Torres FR, Filho HVR, Silveira LR, Figueira ACM. PPARγ S273 Phosphorylation Modifies the Dynamics of Coregulator Proteins Recruitment. Front Endocrinol (Lausanne) 2020; 11:561256. [PMID: 33329381 PMCID: PMC7729135 DOI: 10.3389/fendo.2020.561256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 10/20/2020] [Indexed: 11/24/2022] Open
Abstract
The nuclear receptor PPARγ is essential to maintain whole-body glucose homeostasis and insulin sensitivity, acting as a master regulator of adipogenesis, lipid, and glucose metabolism. Its activation through natural or synthetic ligands induces the recruitment of coactivators, leading to transcription of target genes such as cytokines and hormones. More recently, post translational modifications, such as PPARγ phosphorylation at Ser273 by CDK5 in adipose tissue, have been linked to insulin resistance trough the dysregulation of expression of a specific subset of genes. Here, we investigate how this phosphorylation may disturb the interaction between PPARγ and some coregulator proteins as a new mechanism that may leads to insulin resistance. Through cellular and in vitro assays, we show that PPARγ phosphorylation inhibition increased the activation of the receptor, therefore the increased recruitment of PGC1-α and TIF2 coactivators, whilst decreases the interaction with SMRT and NCoR corepressors. Moreover, our results show a shift in the coregulators interaction domains preferences, suggesting additional interaction interfaces formed between the phosphorylated PPARγ and some coregulator proteins. Also, we observed that the CDK5 presence disturb the PPARγ-coregulator's synergy, decreasing interaction with PGC1-α, TIF2, and NCoR, but increasing coupling of SMRT. Finally, we conclude that the insulin resistance provoked by PPARγ phosphorylation is linked to a differential coregulators recruitment, which may promote dysregulation in gene expression.
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Affiliation(s)
- Marieli Mariano Gonçalves Dias
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
- Graduate Program in Functional and Molecular Biology, Institute of Biology, State University of Campinas (Unicamp), Campinas, Brazil
| | | | - Thais Helena Tittanegro
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - André Gustavo de Oliveira
- Mitochondrial Molecular Biology Laboratory, Obesity and Comorbidities Research Center (OCRC), Campinas, Brazil
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Albane Le Maire
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
- Centre de Biochimie Structurale CNRS, Université de Montpellier, Montpellier, France
| | - Felipe Rafael Torres
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Helder Veras Ribeiro Filho
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Leonardo Reis Silveira
- Mitochondrial Molecular Biology Laboratory, Obesity and Comorbidities Research Center (OCRC), Campinas, Brazil
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Ana Carolina Migliorini Figueira
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
- Graduate Program in Functional and Molecular Biology, Institute of Biology, State University of Campinas (Unicamp), Campinas, Brazil
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8
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The PPAR Ω Pocket: Renewed Opportunities for Drug Development. PPAR Res 2020; 2020:9657380. [PMID: 32695150 PMCID: PMC7351019 DOI: 10.1155/2020/9657380] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 05/13/2020] [Indexed: 12/13/2022] Open
Abstract
The past decade of PPARγ research has dramatically improved our understanding of the structural and mechanistic bases for the diverging physiological effects of different classes of PPARγ ligands. The discoveries that lie at the heart of these developments have enabled the design of a new class of PPARγ ligands, capable of isolating central therapeutic effects of PPARγ modulation, while displaying markedly lower toxicities than previous generations of PPARγ ligands. This review examines the emerging framework around the design of these ligands and seeks to unite its principles with the development of new classes of ligands for PPARα and PPARβ/δ. The focus is on the relationships between the binding modes of ligands, their influence on PPAR posttranslational modifications, and gene expression patterns. Specifically, we encourage the design and study of ligands that primarily bind to the Ω pockets of PPARα and PPARβ/δ. In support of this development, we highlight already reported ligands that if studied in the context of this new framework may further our understanding of the gene programs regulated by PPARα and PPARβ/δ. Moreover, recently developed pharmacological tools that can be utilized in the search for ligands with new binding modes are also presented.
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9
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Harris DA, Mina A, Cabarkapa D, Heshmati K, Subramaniam R, Banks AS, Tavakkoli A, Sheu EG. Sleeve gastrectomy enhances glucose utilization and remodels adipose tissue independent of weight loss. Am J Physiol Endocrinol Metab 2020; 318:E678-E688. [PMID: 32069072 PMCID: PMC7395476 DOI: 10.1152/ajpendo.00441.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sleeve gastrectomy (SG) induces weight loss-independent improvements in glucose homeostasis by unknown mechanisms. We sought to identify the metabolic adaptations responsible for these improvements. Nonobese C57BL/6J mice on standard chow underwent SG or sham surgery. Functional testing and indirect calorimetry were used to capture metabolic phenotypes. Tissue-specific glucose uptake was assessed by 18-fluorodeoxyglucose (18-FDG) PET/computed tomography, and RNA sequencing was used for gene-expression analysis. In this model, SG induced durable improvements in glucose tolerance in the absence of changes in weight, body composition, or food intake. Indirect calorimetry revealed that SG increased the average respiratory exchange ratio toward 1.0, indicating a weight-independent, systemic shift to carbohydrate utilization. Following SG, orally administered 18-FDG preferentially localized to white adipose depots, showing tissue-specific increases in glucose utilization induced by surgery. Transcriptional analysis with RNA sequencing demonstrated that increased glucose uptake in the visceral adipose tissue was associated with upregulation in transcriptional pathways involved in energy metabolism, adipocyte maturation, and adaptive and innate immune cell chemotaxis and differentiation. SG induces a rapid, weight loss-independent shift toward glucose utilization and transcriptional remodeling of metabolic and immune pathways in visceral adipose tissue. Continued study of this early post-SG physiology may lead to a better understanding of the anti-diabetic mechanisms of bariatric surgery.
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Affiliation(s)
- David A Harris
- Laboratory for Surgical and Metabolic Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amir Mina
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Dimitrije Cabarkapa
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Keyvan Heshmati
- Laboratory for Surgical and Metabolic Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Renuka Subramaniam
- Laboratory for Surgical and Metabolic Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Alexander S Banks
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Ali Tavakkoli
- Laboratory for Surgical and Metabolic Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eric G Sheu
- Laboratory for Surgical and Metabolic Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
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10
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Tillotson R, Bird A. The Molecular Basis of MeCP2 Function in the Brain. J Mol Biol 2020; 432:1602-1623. [PMID: 31629770 DOI: 10.1016/j.jmb.2019.10.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 12/14/2022]
Abstract
MeCP2 is a reader of the DNA methylome that occupies a large proportion of the genome due to its high abundance and the frequency of its target sites. It has been the subject of extensive study because of its link with 'MECP2-related disorders', of which Rett syndrome is the most prevalent. This review integrates evidence from patient mutation data with results of experimental studies using mouse models, cell lines and in vitro systems to critically evaluate our understanding of MeCP2 protein function. Recent evidence challenges the idea that MeCP2 is a multifunctional hub that integrates diverse processes to underpin neuronal function, suggesting instead that its primary role is to recruit the NCoR1/2 co-repressor complex to methylated sites in the genome, leading to dampening of gene expression.
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Affiliation(s)
- Rebekah Tillotson
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada; Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - Adrian Bird
- Wellcome Centre for Cell Biology, University of Edinburgh, The Michael Swann Building, King's Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK.
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11
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Soledad RB, Charles S, Samarjit D. The secret messages between mitochondria and nucleus in muscle cell biology. Arch Biochem Biophys 2019; 666:52-62. [PMID: 30935885 PMCID: PMC6538274 DOI: 10.1016/j.abb.2019.03.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/01/2019] [Accepted: 03/28/2019] [Indexed: 02/06/2023]
Abstract
Over two thousand proteins are found in the mitochondrial compartment but the mitochondrial genome codes for only 13 proteins. The majority of mitochondrial proteins are products of nuclear genes and are synthesized in the cytosol, then translocated into the mitochondria. Most of the subunits of the five respiratory chain complexes in the inner mitochondrial membrane, which generate a proton gradient across the membrane and produce ATP, are encoded by nuclear genes. Therefore, it is quite clear that import of nuclear-encoded proteins into the mitochondria is essential for mitochondrial function. Nuclear to mitochondrial communication is well studied. However, there is another arm to this communication, mitochondria to nucleus retrograde signaling. This plays an important role in the maintenance of cellular homeostasis, and is less well studied. Several transcription factors, including Sp1, SIRT3 and GSP2, are activated by altered mitochondrial function. These activated transcription factors then translocate to the nucleus. Based on the mitochondrially generated molecular signal, nuclear genes are targeted, which alters transcription of nuclear genes that code for mitochondrial proteins. This review article will mainly focus on this interactive and bi-directional communication between mitochondria and nucleus, and how this communication plays a significant role in muscle cell biology.
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Affiliation(s)
| | - Steenbergen Charles
- Department of Pathology, Johns Hopkins University, Baltimore, MD, United States
| | - Das Samarjit
- Department of Pathology, Johns Hopkins University, Baltimore, MD, United States.
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12
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Liang N, Damdimopoulos A, Goñi S, Huang Z, Vedin LL, Jakobsson T, Giudici M, Ahmed O, Pedrelli M, Barilla S, Alzaid F, Mendoza A, Schröder T, Kuiper R, Parini P, Hollenberg A, Lefebvre P, Francque S, Van Gaal L, Staels B, Venteclef N, Treuter E, Fan R. Hepatocyte-specific loss of GPS2 in mice reduces non-alcoholic steatohepatitis via activation of PPARα. Nat Commun 2019; 10:1684. [PMID: 30975991 PMCID: PMC6459876 DOI: 10.1038/s41467-019-09524-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 03/12/2019] [Indexed: 02/06/2023] Open
Abstract
Obesity triggers the development of non-alcoholic fatty liver disease (NAFLD), which involves alterations of regulatory transcription networks and epigenomes in hepatocytes. Here we demonstrate that G protein pathway suppressor 2 (GPS2), a subunit of the nuclear receptor corepressor (NCOR) and histone deacetylase 3 (HDAC3) complex, has a central role in these alterations and accelerates the progression of NAFLD towards non-alcoholic steatohepatitis (NASH). Hepatocyte-specific Gps2 knockout in mice alleviates the development of diet-induced steatosis and fibrosis and causes activation of lipid catabolic genes. Integrative cistrome, epigenome and transcriptome analysis identifies the lipid-sensing peroxisome proliferator-activated receptor α (PPARα, NR1C1) as a direct GPS2 target. Liver gene expression data from human patients reveal that Gps2 expression positively correlates with a NASH/fibrosis gene signature. Collectively, our data suggest that the GPS2-PPARα partnership in hepatocytes coordinates the progression of NAFLD in mice and in humans and thus might be of therapeutic interest.
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Affiliation(s)
- Ning Liang
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden
| | | | - Saioa Goñi
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Zhiqiang Huang
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Lise-Lotte Vedin
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Tomas Jakobsson
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Marco Giudici
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Osman Ahmed
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Matteo Pedrelli
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Serena Barilla
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Fawaz Alzaid
- INSERM, Cordeliers Research Centre, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Paris, 75013, France
| | - Arturo Mendoza
- Division of Endocrinology, Diabetes and Metabolism, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, 10021, USA
| | - Tarja Schröder
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Raoul Kuiper
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
| | - Paolo Parini
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 14157, Sweden
- Department of Medicine Huddinge, Karolinska Institutet, Huddinge, 14157, Sweden
- Inflammation and Infection Theme, Karolinska University Hospital, Huddinge, 14157, Sweden
| | - Anthony Hollenberg
- Division of Endocrinology, Diabetes and Metabolism, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, 10021, USA
| | - Philippe Lefebvre
- University Lille, INSERM, CHU Lillie, Institut Pasteur de Lille, U1011-EGID, Lille, F-59000, France
| | - Sven Francque
- Department of Gastroenterology and Hepatology, University of Antwerp, Antwerp, 2610, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, 2610, Belgium
| | - Luc Van Gaal
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, 2610, Belgium
- Department of Endocrinology, Diabetology and Metabolism, University of Antwerp, Antwerp, 2610, Belgium
| | - Bart Staels
- University Lille, INSERM, CHU Lillie, Institut Pasteur de Lille, U1011-EGID, Lille, F-59000, France
| | - Nicolas Venteclef
- INSERM, Cordeliers Research Centre, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Paris, 75013, France
| | - Eckardt Treuter
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden.
| | - Rongrong Fan
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 14157, Sweden.
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13
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Korbecki J, Bobiński R, Dutka M. Self-regulation of the inflammatory response by peroxisome proliferator-activated receptors. Inflamm Res 2019; 68:443-458. [PMID: 30927048 PMCID: PMC6517359 DOI: 10.1007/s00011-019-01231-1] [Citation(s) in RCA: 194] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 02/24/2019] [Accepted: 03/22/2019] [Indexed: 12/14/2022] Open
Abstract
The peroxisome proliferator-activated receptor (PPAR) family includes three transcription factors: PPARα, PPARβ/δ, and PPARγ. PPAR are nuclear receptors activated by oxidised and nitrated fatty acid derivatives as well as by cyclopentenone prostaglandins (PGA2 and 15d-PGJ2) during the inflammatory response. This results in the modulation of the pro-inflammatory response, preventing it from being excessively activated. Other activators of these receptors are nonsteroidal anti-inflammatory drug (NSAID) and fatty acids, especially polyunsaturated fatty acid (PUFA) (arachidonic acid, ALA, EPA, and DHA). The main function of PPAR during the inflammatory reaction is to promote the inactivation of NF-κB. Possible mechanisms of inactivation include direct binding and thus inactivation of p65 NF-κB or ubiquitination leading to proteolytic degradation of p65 NF-κB. PPAR also exert indirect effects on NF-κB. They promote the expression of antioxidant enzymes, such as catalase, superoxide dismutase, or heme oxygenase-1, resulting in a reduction in the concentration of reactive oxygen species (ROS), i.e., secondary transmitters in inflammatory reactions. PPAR also cause an increase in the expression of IκBα, SIRT1, and PTEN, which interferes with the activation and function of NF-κB in inflammatory reactions.
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Affiliation(s)
- Jan Korbecki
- Department of Molecular Biology, School of Medicine in Katowice, Medical University of Silesia, Medyków 18 Str., 40-752, Katowice, Poland. .,Department of Biochemistry and Molecular Biology, Faculty of Health Sciences, University of Bielsko-Biala, Willowa 2 Str., 43-309, Bielsko-Biała, Poland.
| | - Rafał Bobiński
- Department of Biochemistry and Molecular Biology, Faculty of Health Sciences, University of Bielsko-Biala, Willowa 2 Str., 43-309, Bielsko-Biała, Poland
| | - Mieczysław Dutka
- Department of Biochemistry and Molecular Biology, Faculty of Health Sciences, University of Bielsko-Biala, Willowa 2 Str., 43-309, Bielsko-Biała, Poland
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14
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Cardamone MD, Tanasa B, Cederquist CT, Huang J, Mahdaviani K, Li W, Rosenfeld MG, Liesa M, Perissi V. Mitochondrial Retrograde Signaling in Mammals Is Mediated by the Transcriptional Cofactor GPS2 via Direct Mitochondria-to-Nucleus Translocation. Mol Cell 2019; 69:757-772.e7. [PMID: 29499132 DOI: 10.1016/j.molcel.2018.01.037] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 12/15/2017] [Accepted: 01/29/2018] [Indexed: 12/24/2022]
Abstract
As most of the mitochondrial proteome is encoded in the nucleus, mitochondrial functions critically depend on nuclear gene expression and bidirectional mito-nuclear communication. However, mitochondria-to-nucleus communication pathways in mammals are incompletely understood. Here, we identify G-Protein Pathway Suppressor 2 (GPS2) as a mediator of mitochondrial retrograde signaling and a transcriptional activator of nuclear-encoded mitochondrial genes. GPS2-regulated translocation from mitochondria to nucleus is essential for the transcriptional activation of a nuclear stress response to mitochondrial depolarization and for supporting basal mitochondrial biogenesis in differentiating adipocytes and brown adipose tissue (BAT) from mice. In the nucleus, GPS2 recruitment to target gene promoters regulates histone H3K9 demethylation and RNA POL2 activation through inhibition of Ubc13-mediated ubiquitination. These findings, together, reveal an additional layer of regulation of mitochondrial gene transcription, uncover a direct mitochondria-nuclear communication pathway, and indicate that GPS2 retrograde signaling is a key component of the mitochondrial stress response in mammals.
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Affiliation(s)
- Maria Dafne Cardamone
- Biochemistry Department, Boston University School of Medicine, Boston, MA 02118, USA
| | - Bogdan Tanasa
- Howard Hughes Medical Institute, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Carly T Cederquist
- Biochemistry Department, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jiawen Huang
- Biochemistry Department, Boston University School of Medicine, Boston, MA 02118, USA
| | - Kiana Mahdaviani
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Wenbo Li
- Howard Hughes Medical Institute, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael G Rosenfeld
- Howard Hughes Medical Institute, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Marc Liesa
- Department of Medicine, Division of Endocrinology and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Valentina Perissi
- Biochemistry Department, Boston University School of Medicine, Boston, MA 02118, USA.
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15
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Liang N, Jakobsson T, Fan R, Treuter E. The Nuclear Receptor-Co-repressor Complex in Control of Liver Metabolism and Disease. Front Endocrinol (Lausanne) 2019; 10:411. [PMID: 31293521 PMCID: PMC6606711 DOI: 10.3389/fendo.2019.00411] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/07/2019] [Indexed: 12/21/2022] Open
Abstract
Hepatocytes are the major cell-type in the liver responsible for the coordination of metabolism in response to multiple signaling inputs. Coordination occurs primarily at the level of gene expression via transcriptional networks composed of transcription factors, in particular nuclear receptors (NRs), and associated co-regulators, including chromatin-modifying complexes. Disturbance of these networks by genetic, environmental or nutritional factors can lead to metabolic dysregulation and has been linked to the progression of non-alcoholic fatty liver disease (NAFLD) toward steatohepatitis and even liver cancer. Since there are currently no approved therapies, major efforts are dedicated to identify the critical factors that can be employed for drug development. Amongst the identified factors with clinical significance are currently lipid-sensing NRs including PPARs, LXRs, and FXR. However, major obstacles of NR-targeting are the undesired side effects associated with the genome-wide NR activities in multiple cell-types. Thus, of particular interest are co-regulators that determine NR activities, context-selectivity, and associated chromatin states. Current research on the role of co-regulators in hepatocytes is still premature due to the large number of candidates, the limited number of available mouse models, and the technical challenges in studying their chromatin occupancy. As a result, how NR-co-regulator networks in hepatocytes are coordinated by extracellular signals, and how NR-pathway selectivity is achieved, remains currently poorly understood. We will here review a notable exception, namely a fundamental transcriptional co-repressor complex that during the past decade has become the probably most-studied and best-understood physiological relevant co-regulator in hepatocytes. This multiprotein complex contains the core subunits HDAC3, NCOR, SMRT, TBL1, TBLR1, and GPS2 and is referred to as the "NR-co-repressor complex." We will particularly discuss recent advances in characterizing hepatocyte-specific loss-of-function mouse models and in applying genome-wide sequencing approaches including ChIP-seq. Both have been instrumental to uncover the role of each of the subunits under physiological conditions and in disease models, but they also revealed insights into the NR target range and genomic mechanisms of action of the co-repressor complex. We will integrate a discussion of translational aspects about the role of the complex in NAFLD pathways and in particular about the hypothesis that patient-specific alterations of specific subunits may determine NAFLD susceptibility and the therapeutic outcomes of NR-directed treatments.
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Affiliation(s)
- Ning Liang
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Tomas Jakobsson
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden
| | - Rongrong Fan
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Eckardt Treuter
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
- *Correspondence: Eckardt Treuter
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16
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Lentucci C, Belkina AC, Cederquist CT, Chan M, Johnson HE, Prasad S, Lopacinski A, Nikolajczyk BS, Monti S, Snyder-Cappione J, Tanasa B, Cardamone MD, Perissi V. Inhibition of Ubc13-mediated Ubiquitination by GPS2 Regulates Multiple Stages of B Cell Development. J Biol Chem 2016; 292:2754-2772. [PMID: 28039360 DOI: 10.1074/jbc.m116.755132] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/21/2016] [Indexed: 12/12/2022] Open
Abstract
Non-proteolytic ubiquitin signaling mediated by Lys63 ubiquitin chains plays a critical role in multiple pathways that are key to the development and activation of immune cells. Our previous work indicates that GPS2 (G-protein Pathway Suppressor 2) is a multifunctional protein regulating TNFα signaling and lipid metabolism in the adipose tissue through modulation of Lys63 ubiquitination events. However, the full extent of GPS2-mediated regulation of ubiquitination and the underlying molecular mechanisms are unknown. Here, we report that GPS2 is required for restricting the activation of TLR and BCR signaling pathways and the AKT/FOXO1 pathway in immune cells based on direct inhibition of Ubc13 enzymatic activity. Relevance of this regulatory strategy is confirmed in vivo by B cell-targeted deletion of GPS2, resulting in developmental defects at multiple stages of B cell differentiation. Together, these findings reveal that GPS2 genomic and non-genomic functions are critical for the development and cellular homeostasis of B cells.
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Affiliation(s)
| | - Anna C Belkina
- the Flow Cytometry Core Facility, Boston University School of Medicine, Boston, Massachusetts 02118 and.,Microbiology, and
| | | | | | | | | | | | | | | | - Jennifer Snyder-Cappione
- the Flow Cytometry Core Facility, Boston University School of Medicine, Boston, Massachusetts 02118 and.,Microbiology, and
| | - Bogdan Tanasa
- the Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305
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17
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Cederquist CT, Lentucci C, Martinez-Calejman C, Hayashi V, Orofino J, Guertin D, Fried SK, Lee MJ, Cardamone MD, Perissi V. Systemic insulin sensitivity is regulated by GPS2 inhibition of AKT ubiquitination and activation in adipose tissue. Mol Metab 2016; 6:125-137. [PMID: 28123943 PMCID: PMC5220281 DOI: 10.1016/j.molmet.2016.10.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 10/20/2016] [Accepted: 10/24/2016] [Indexed: 02/06/2023] Open
Abstract
Objective Insulin signaling plays a unique role in the regulation of energy homeostasis and the impairment of insulin action is associated with altered lipid metabolism, obesity, and Type 2 Diabetes. The main aim of this study was to provide further insight into the regulatory mechanisms governing the insulin signaling pathway by investigating the role of non-proteolytic ubiquitination in insulin-mediated activation of AKT. Methods The molecular mechanism of AKT regulation through ubiquitination is first dissected in vitro in 3T3-L1 preadipocytes and then validated in vivo using mice with adipo-specific deletion of GPS2, an endogenous inhibitor of Ubc13 activity (GPS2-AKO mice). Results Our results indicate that K63 ubiquitination is a critical component of AKT activation in the insulin signaling pathway and that counter-regulation of this step is provided by GPS2 preventing AKT ubiquitination through inhibition of Ubc13 enzymatic activity. Removal of this negative checkpoint, through GPS2 downregulation or genetic deletion, results in sustained activation of insulin signaling both in vitro and in vivo. As a result, the balance between lipid accumulation and utilization is shifted toward storage in the adipose tissue and GPS2-AKO mice become obese under normal laboratory chow diet. However, the adipose tissue of GPS2-AKO mice is not inflamed, the levels of circulating adiponectin are elevated, and systemic insulin sensitivity is overall improved. Conclusions Our findings characterize a novel layer of regulation of the insulin signaling pathway based on non-proteolytic ubiquitination of AKT and define GPS2 as a previously unrecognized component of the insulin signaling cascade. In accordance with this role, we have shown that GPS2 presence in adipocytes modulates systemic metabolism by restricting the activation of insulin signaling during the fasted state, whereas in absence of GPS2, the adipose tissue is more efficient at lipid storage, and obesity becomes uncoupled from inflammation and insulin resistance. Ubc13-mediated ubiquitination of AKT is required for activation of the insulin signaling pathway. GPS2 regulates insulin signaling by inhibiting AKT ubiquitination and activation. Adipo-specific deletion of GPS2 results in increased adiposity and altered lipid flux in the adipocytes. GPS2-AKO mice have higher levels of circulating adiponectin and are insulin sensitive despite being obese.
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Affiliation(s)
- Carly T Cederquist
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA
| | - Claudia Lentucci
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA
| | - Camila Martinez-Calejman
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation St, Worcester, MA 01605, USA
| | - Vanessa Hayashi
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA
| | - Joseph Orofino
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA
| | - David Guertin
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation St, Worcester, MA 01605, USA
| | - Susan K Fried
- Diabetes Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, 1 Gustav Levy Place, New York, NY 10029, USA
| | - Mi-Jeong Lee
- Department of Medicine, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA
| | - M Dafne Cardamone
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA
| | - Valentina Perissi
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St, Boston, MA 02118, USA.
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18
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Lin JC. Impacts of Alternative Splicing Events on the Differentiation of Adipocytes. Int J Mol Sci 2015; 16:22169-89. [PMID: 26389882 PMCID: PMC4613302 DOI: 10.3390/ijms160922169] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 09/07/2015] [Accepted: 09/07/2015] [Indexed: 02/07/2023] Open
Abstract
Alternative splicing was found to be a common phenomenon after the advent of whole transcriptome analyses or next generation sequencing. Over 90% of human genes were demonstrated to undergo at least one alternative splicing event. Alternative splicing is an effective mechanism to spatiotemporally expand protein diversity, which influences the cell fate and tissue development. The first focus of this review is to highlight recent studies, which demonstrated effects of alternative splicing on the differentiation of adipocytes. Moreover, use of evolving high-throughput approaches, such as transcriptome analyses (RNA sequencing), to profile adipogenic transcriptomes, is also addressed.
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Affiliation(s)
- Jung-Chun Lin
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan.
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19
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Huang J, Cardamone MD, Johnson HE, Neault M, Chan M, Floyd ZE, Mallette FA, Perissi V. Exchange Factor TBL1 and Arginine Methyltransferase PRMT6 Cooperate in Protecting G Protein Pathway Suppressor 2 (GPS2) from Proteasomal Degradation. J Biol Chem 2015; 290:19044-54. [PMID: 26070566 DOI: 10.1074/jbc.m115.637660] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Indexed: 12/18/2022] Open
Abstract
G protein pathway suppressor 2 (GPS2) is a multifunctional protein involved in the regulation of a number of metabolic organs. First identified as part of the NCoR-SMRT corepressor complex, GPS2 is known to play an important role in the nucleus in the regulation of gene transcription and meiotic recombination. In addition, we recently reported a non-transcriptional role of GPS2 as an inhibitor of the proinflammatory TNFα pathway in the cytosol. Although this suggests that the control of GPS2 localization may be an important determinant of its molecular functions, a clear understanding of GPS2 differential targeting to specific cellular locations is still lacking. Here we show that a fine balance between protein stabilization and degradation tightly regulates GPS2 nuclear function. Our findings indicate that GPS2 is degraded upon polyubiquitination by the E3 ubiquitin ligase Siah2. Unexpectedly, interaction with the exchange factor TBL1 is required to protect GPS2 from degradation, with methylation of GPS2 by arginine methyltransferase PRMT6 regulating the interaction with TBL1 and inhibiting proteasome-dependent degradation. Overall, our findings indicate that regulation of GPS2 by posttranslational modifications provides an effective strategy for modulating its molecular function within the nuclear compartment.
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Affiliation(s)
- Jiawen Huang
- From the Biochemistry Department, Boston University School of Medicine, Boston, Massachusetts 02118
| | - M Dafne Cardamone
- From the Biochemistry Department, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Holly E Johnson
- From the Biochemistry Department, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Mathieu Neault
- the Chromatin Structure and Cellular Senescence Research Unit, Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Quebec H1T 2M4, Canada
| | - Michelle Chan
- From the Biochemistry Department, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Z Elizabeth Floyd
- the Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, and
| | - Frédérick A Mallette
- the Chromatin Structure and Cellular Senescence Research Unit, Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Quebec H1T 2M4, Canada, the Département de Médecine, Université de Montréal, Montréal, Quebec H1T 2M4, Canada
| | - Valentina Perissi
- From the Biochemistry Department, Boston University School of Medicine, Boston, Massachusetts 02118,
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