1
|
Woo JR, Bae SH, Wales TE, Engen JR, Lee J, Jang H, Park S. The serine phosphorylations in the IRS-1 PIR domain abrogate IRS-1 and IR interaction. Proc Natl Acad Sci U S A 2024; 121:e2401716121. [PMID: 38625937 PMCID: PMC11046688 DOI: 10.1073/pnas.2401716121] [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: 02/02/2024] [Accepted: 03/16/2024] [Indexed: 04/18/2024] Open
Abstract
Serine phosphorylations on insulin receptor substrate 1 (IRS-1) by diverse kinases aoccur widely during obesity-, stress-, and inflammation-induced conditions in models of insulin resistance and type 2 diabetes. In this study, we define a region within the human IRS-1, which is directly C-terminal to the PTB domain encompassing numerous serine phosphorylation sites including Ser307 (mouse Ser302) and Ser312 (mouse 307) creating a phosphorylation insulin resistance (PIR) domain. We demonstrate that the IRS-1 PTB-PIR with its unphosphorylated serine residues interacts with the insulin receptor (IR) but loses the IR-binding when they are phosphorylated. Surface plasmon resonance studies further confirm that the PTB-PIR binds stronger to IR than just the PTB domain, and that phosphorylations at Ser307, Ser312, Ser315, and Ser323 within the PIR domain result in abrogating the binding. Insulin-responsive cells containing the mutant IRS-1 with all these four serines changed into glutamates to mimic phosphorylations show decreased levels of phosphorylations in IR, IRS-1, and AKT compared to the wild-type IRS-1. Hydrogen-deuterium exchange mass spectrometry experiments indicating the PIR domain interacting with the N-terminal lobe and the hinge regions of the IR kinase domain further suggest the possibility that the IRS-1 PIR domain protects the IR from the PTP1B-mediated dephosphorylation.
Collapse
Affiliation(s)
- Ju Rang Woo
- Division of Convergence Technology, New Drug Development Center, KBIOHealth, Cheongju28160, Republic of Korea
| | - Seung-Hyun Bae
- Division of Rare and Refractory Cancer, Research Institute, National Cancer Center,Goyang10408, Republic of Korea
- Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy,Goyang10408, Republic of Korea
| | - Thomas E. Wales
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA02115
| | - John R. Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA02115
| | - Jongsoon Lee
- Soonchunhyang Institute of Medi-Bio Science, Soonchunhyang University, Cheonan31151, Republic of Korea
| | - Hyonchol Jang
- Division of Rare and Refractory Cancer, Research Institute, National Cancer Center,Goyang10408, Republic of Korea
- Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy,Goyang10408, Republic of Korea
| | - SangYoun Park
- School of Systems Biomedical Science, Soongsil University, Seoul06978, Republic of Korea
- Integrative Institute of Basic Sciences, Soongsil University, Seoul06978, Republic of Korea
| |
Collapse
|
2
|
Domma AJ, Henderson LA, Goodrum FD, Moorman NJ, Kamil JP. Human cytomegalovirus attenuates AKT activity by destabilizing insulin receptor substrate proteins. J Virol 2023; 97:e0056323. [PMID: 37754763 PMCID: PMC10617551 DOI: 10.1128/jvi.00563-23] [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: 04/15/2023] [Accepted: 08/09/2023] [Indexed: 09/28/2023] Open
Abstract
IMPORTANCE Human cytomegalovirus (HCMV) requires inactivation of AKT to efficiently replicate, yet how AKT is shut off during HCMV infection has remained unclear. We show that UL38, an HCMV protein that activates mTORC1, is necessary and sufficient to destabilize insulin receptor substrate 1 (IRS1), a model insulin receptor substrate (IRS) protein. Degradation of IRS proteins in settings of excessive mTORC1 activity is an important mechanism for insulin resistance. When IRS proteins are destabilized, PI3K cannot be recruited to growth factor receptor complexes, and hence, AKT membrane recruitment, a rate limiting step in its activation, fails to occur. Despite its penchant for remodeling host cell signaling pathways, our results reveal that HCMV relies upon a cell-intrinsic negative regulatory feedback loop to inactivate AKT. Given that pharmacological inhibition of PI3K/AKT potently induces HCMV reactivation from latency, our findings also imply that the expression of UL38 activity must be tightly regulated within latently infected cells to avoid spontaneous reactivation.
Collapse
Affiliation(s)
- Anthony J. Domma
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, USA
| | - Lauren A. Henderson
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, USA
| | - Felicia D. Goodrum
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- Bio5 Institute, University of Arizona, Tucson, Arizona, USA
| | - Nathaniel J. Moorman
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jeremy P. Kamil
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, USA
| |
Collapse
|
3
|
Okita K, Hikiji H, Koga A, Nagai-Yoshioka Y, Yamasaki R, Mitsugi S, Fujii W, Ariyoshi W. Ascorbic acid enhances chondrocyte differentiation of ATDC5 by accelerating insulin receptor signaling. Cell Biol Int 2023; 47:1737-1748. [PMID: 37381608 DOI: 10.1002/cbin.12067] [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: 10/14/2022] [Revised: 05/06/2023] [Accepted: 06/20/2023] [Indexed: 06/30/2023]
Abstract
Chondrogenesis is strictly regulated by several factors, including cytokines, hormones, and extracellular matrix proteins. Mouse teratocarcinoma-derived lineage cells, differentiate into chondrocytes in the presence of insulin. Although ascorbic acid promotes chondrogenic differentiation, the detailed regulative mechanisms underlying its role in chondrogenesis remain unclear. Therefore, in this study, we evaluated the effects of ascorbic acid on insulin-induced chondrogenic differentiation of ATDC5 cells and the underlying intracellular signaling. The results revealed that insulin-stimulated collagen deposition, matrix formation, calcification, and expression of chondrogenic differentiation marker genes in ATDC5 cells. This enhancement by insulin was amplified with the addition of ascorbic acid. Molecular analysis revealed that the activation of insulin-induced phosphoinositide 3-kinase (PI3K)/Akt signaling was enhanced in the presence of ascorbic acid. In contrast, Wnt/β-catenin signaling was suppressed during chondrocyte differentiation via upregulation of the Wnt agonist, secreted Frizzled-related protein 1 (sFRP-1) and 3 (sFRP-3). Notably, ascorbic acid upregulated the expression of insulin receptors and their substrates (IRS-1 and IRS-2). Furthermore, ascorbic acid reversed the suppression of IRS-1 and IRS-2 protein by insulin. These results indicate that ascorbic acid positively regulates the chondrogenic differentiation of ATDC5 cells via enhancement of insulin signaling. Our findings provide a substantial basis for further elucidation of the regulatory mechanisms of chondrocyte differentiation and the pathophysiology of OA, thus aiding in development of effective treatment strategies.
Collapse
Affiliation(s)
- Kaede Okita
- Department of Health Promotion, Division of Infections and Molecular Biology, Kyushu Dental University, Fukuoka, Japan
- School of Oral Health Sciences, Faculty of Dentistry, Kyushu Dental University, Fukuoka, Japan
| | - Hisako Hikiji
- School of Oral Health Sciences, Faculty of Dentistry, Kyushu Dental University, Fukuoka, Japan
| | - Ayaka Koga
- Department of Health Promotion, Division of Infections and Molecular Biology, Kyushu Dental University, Fukuoka, Japan
- School of Oral Health Sciences, Faculty of Dentistry, Kyushu Dental University, Fukuoka, Japan
| | - Yoshie Nagai-Yoshioka
- Department of Health Promotion, Division of Infections and Molecular Biology, Kyushu Dental University, Fukuoka, Japan
| | - Ryota Yamasaki
- Department of Health Promotion, Division of Infections and Molecular Biology, Kyushu Dental University, Fukuoka, Japan
| | - Sho Mitsugi
- Department of Science of Physical Functions, Division of Oral and Maxillofacial Surgery, Kyushu Dental University, Fukuoka, Japan
| | - Wataru Fujii
- School of Oral Health Sciences, Faculty of Dentistry, Kyushu Dental University, Fukuoka, Japan
| | - Wataru Ariyoshi
- Department of Health Promotion, Division of Infections and Molecular Biology, Kyushu Dental University, Fukuoka, Japan
| |
Collapse
|
4
|
Domma AJ, Goodrum FD, Moorman NJ, Kamil JP. Human cytomegalovirus attenuates AKT activity by destabilizing insulin receptor substrate proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537203. [PMID: 37131605 PMCID: PMC10153195 DOI: 10.1101/2023.04.17.537203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The phosphoinositide 3-kinase (PI3K)/AKT pathway plays crucial roles in cell viability and protein synthesis and is frequently co-opted by viruses to support their replication. Although many viruses maintain high levels of AKT activity during infection, other viruses, such as vesicular stomatitis virus and human cytomegalovirus (HCMV), cause AKT to accumulate in an inactive state. To efficiently replicate, HCMV requires FoxO transcription factors to localize to the infected cell nucleus (Zhang et. al. mBio 2022), a process directly antagonized by AKT. Therefore, we sought to investigate how HCMV inactivates AKT to achieve this. Subcellular fractionation and live cell imaging studies indicated that AKT failed to recruit to membranes upon serum-stimulation of infected cells. However, UV-inactivated virions were unable to render AKT non-responsive to serum, indicating a requirement for de novo viral gene expression. Interestingly, we were able to identify that UL38 (pUL38), a viral activator of mTORC1, is required to diminish AKT responsiveness to serum. mTORC1 contributes to insulin resistance by causing proteasomal degradation of insulin receptor substrate (IRS) proteins, such as IRS1, which are necessary for the recruitment of PI3K to growth factor receptors. In cells infected with a recombinant HCMV disrupted for UL38 , AKT responsiveness to serum is retained and IRS1 is not degraded. Furthermore, ectopic expression of UL38 in uninfected cells induces IRS1 degradation, inactivating AKT. These effects of UL38 were reversed by the mTORC1 inhibitor, rapamycin. Collectively, our results demonstrate that HCMV relies upon a cell-intrinsic negative feedback loop to render AKT inactive during productive infection.
Collapse
Affiliation(s)
- Anthony J. Domma
- Department of Microbiology and Immunology, LSU Health Sciences Center Shreveport, Shreveport Louisiana, USA
| | - Felicia D. Goodrum
- Department of Immunobiology, University of Arizona, Tucson, AZ, USA
- Bio5 Institute, University of Arizona, Tucson, AZ, USA
| | - Nathaniel J. Moorman
- Department of Microbiology and Immunology, UNC Chapel Hill, Chapel Hill, NC, USA
| | - Jeremy P. Kamil
- Department of Microbiology and Immunology, LSU Health Sciences Center Shreveport, Shreveport Louisiana, USA
| |
Collapse
|
5
|
Zhang ZD, Ren H, Wang WX, Shen GY, Huang JJ, Zhan MQ, Tang JJ, Yu X, Zhang YZ, Liang D, Yang ZD, Jiang XB. IGF-1R/β-catenin signaling axis is involved in type 2 diabetic osteoporosis. J Zhejiang Univ Sci B 2020; 20:838-848. [PMID: 31489803 DOI: 10.1631/jzus.b1800648] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Insulin-like growth factor-1 receptor (IGF-1R) is involved in both glucose and bone metabolism. IGF-1R signaling regulates the canonical Wnt/β-catenin signaling pathway. In this study, we investigated whether the IGF-1R/ β-catenin signaling axis plays a role in the pathogenesis of diabetic osteoporosis (DOP). Serum from patients with or without DOP was collected to measure the IGF-1R level using enzyme-linked immunosorbent assay (ELISA). Rats were given streptozotocin following a four-week high-fat diet induction (DOP group), or received vehicle after the same period of a normal diet (control group). Dual energy X-ray absorption, a biomechanics test, and hematoxylin-eosin (HE) staining were performed to evaluate bone mass, bone strength, and histomorphology, respectively, in vertebrae. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to measure the total and phosphorylation levels of IGF-1R, glycogen synthase kinase-3β (GSK-3β), and β-catenin. The serum IGF-1R level was much higher in patients with DOP than in controls. DOP rats exhibited strikingly reduced bone mass and attenuated compression strength of the vertebrae compared with the control group. HE staining showed that the histomorphology of DOP vertebrae was seriously impaired, which manifested as decreased and thinned trabeculae and increased lipid droplets within trabeculae. PCR analysis demonstrated that IGF-1R mRNA expression was significantly up-regulated, and western blotting detection showed that phosphorylation levels of IGF-1R, GSK-3β, and β-catenin were enhanced in DOP rat vertebrae. Our results suggest that the IGF-1R/β-catenin signaling axis plays a role in the pathogenesis of DOP. This may contribute to development of the underlying therapeutic target for DOP.
Collapse
Affiliation(s)
- Zhi-Da Zhang
- The First Clinical School, Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Hui Ren
- Department of Spinal Surgery, the First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Wei-Xi Wang
- The First Clinical School, Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Geng-Yang Shen
- Department of Spinal Surgery, the First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Jin-Jing Huang
- The First Clinical School, Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Mei-Qi Zhan
- The First Clinical School, Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Jing-Jing Tang
- Department of Spinal Surgery, the First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Xiang Yu
- The First Clinical School, Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Yu-Zhuo Zhang
- School of Basic Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - De Liang
- Department of Spinal Surgery, the First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Zhi-Dong Yang
- Department of Spinal Surgery, the First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Xiao-Bing Jiang
- Department of Spinal Surgery, the First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China.,Lingnan Medical Research Center of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| |
Collapse
|
6
|
Frendo-Cumbo S, Jaldin-Fincati JR, Coyaud E, Laurent EMN, Townsend LK, Tan JMJ, Xavier RJ, Pillon NJ, Raught B, Wright DC, Brumell JH, Klip A. Deficiency of the autophagy gene ATG16L1 induces insulin resistance through KLHL9/KLHL13/CUL3-mediated IRS1 degradation. J Biol Chem 2019; 294:16172-16185. [PMID: 31515271 DOI: 10.1074/jbc.ra119.009110] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 08/29/2019] [Indexed: 12/23/2022] Open
Abstract
Connections between deficient autophagy and insulin resistance have emerged, however, the mechanism through which reduced autophagy impairs insulin-signaling remains unknown. We examined mouse embryonic fibroblasts lacking Atg16l1 (ATG16L1 KO mouse embryonic fibroblasts (MEFs)), an essential autophagy gene, and observed deficient insulin and insulin-like growth factor-1 signaling. ATG16L1 KO MEFs displayed reduced protein content of insulin receptor substrate-1 (IRS1), pivotal to insulin signaling, whereas IRS1myc overexpression recovered downstream insulin signaling. Endogenous IRS1 protein content and insulin signaling were restored in ATG16L1 KO mouse embryonic fibroblasts (MEF) upon proteasome inhibition. Through proximity-dependent biotin identification (BioID) and co-immunoprecipitation, we found that Kelch-like proteins KLHL9 and KLHL13, which together form an E3 ubiquitin (Ub) ligase complex with cullin 3 (CUL3), are novel IRS1 interactors. Expression of Klhl9 and Klhl13 was elevated in ATG16L1 KO MEFs and siRNA-mediated knockdown of Klhl9, Klhl13, or Cul3 recovered IRS1 expression. Moreover, Klhl13 and Cul3 knockdown increased insulin signaling. Notably, adipose tissue of high-fat fed mice displayed lower Atg16l1 mRNA expression and IRS1 protein content, and adipose tissue KLHL13 and CUL3 expression positively correlated to body mass index in humans. We propose that ATG16L1 deficiency evokes insulin resistance through induction of Klhl9 and Klhl13, which, in complex with Cul3, promote proteasomal IRS1 degradation.
Collapse
Affiliation(s)
- Scott Frendo-Cumbo
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | - Etienne Coyaud
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2C1, Canada
| | - Estelle M N Laurent
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2C1, Canada
| | - Logan K Townsend
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Joel M J Tan
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Ramnik J Xavier
- Gastrointestinal Unit and Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114
| | - Nicolas J Pillon
- Departments of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden 171 77
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2C1, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - David C Wright
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - John Hunter Brumell
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada .,Department of Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,SickKids IBD Centre, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Amira Klip
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada .,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| |
Collapse
|
7
|
Scheufele F, Wolf B, Kruse M, Hartmann T, Lempart J, Mühlich S, Pfeiffer AFH, Field LJ, Charron MJ, Pan ZQ, Engelhardt S, Sarikas A. Evidence for a regulatory role of Cullin-RING E3 ubiquitin ligase 7 in insulin signaling. Cell Signal 2013; 26:233-239. [PMID: 24219910 DOI: 10.1016/j.cellsig.2013.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/01/2013] [Indexed: 01/05/2023]
Abstract
Dysfunctional regulation of signaling pathways downstream of the insulin receptor plays a pivotal role in the pathogenesis of insulin resistance and type 2 diabetes. In this study we report both in vitro and in vivo experimental evidence for a role of Cullin-RING E3 ubiquitin ligase 7 (CRL7) in the regulation of insulin signaling and glucose homeostasis. We show that Cul7(-/-) mouse embryonic fibroblasts displayed enhanced AKT and Erk MAP kinase phosphorylation upon insulin stimulation. Depletion of CUL7 by RNA interference in C2C12 myotubes led to increased activation of insulin signaling pathways and cellular glucose uptake, as well as a reduced capacity of these cells to execute insulin-induced degradation of insulin receptor substrate 1 (IRS1). In vivo, heterozygosity of either Cul7 or Fbxw8, both key components of CRL7, resulted in elevated PI3 kinase/AKT activation in skeletal muscle tissue upon insulin stimulation when compared to wild-type controls. Finally, Cul7(+/-) or Fbxw8(+/-) mice exhibited enhanced insulin sensitivity and plasma glucose clearance. Collectively, our findings point to a yet unrecognized role of CRL7 in insulin-mediated control of glucose homeostasis by restraining PI3 kinase/AKT activities in skeletal muscle cells.
Collapse
Affiliation(s)
- Florian Scheufele
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Benjamin Wolf
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Michael Kruse
- German Institute of Human Nutrition Potsdam-Rehbrücke, Department of Clinical Nutrition, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.,Departments of Biochemistry, Medicine (Endocrinology) and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Thomas Hartmann
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Justine Lempart
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Susanne Mühlich
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, Goethestraße 33, 80336 Munich, Germany
| | - Andreas F H Pfeiffer
- German Institute of Human Nutrition Potsdam-Rehbrücke, Department of Clinical Nutrition, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.,Department of Endocrinology, Diabetes and Nutrition, Charité University Medicine, 10117 Berlin, Germany
| | - Loren J Field
- Krannert Institute of Cardiology, University of Indiana, Indianapolis, IN 46202, USA
| | - Maureen J Charron
- Departments of Biochemistry, Medicine (Endocrinology) and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Zhen-Qiang Pan
- Mount Sinai School of Medicine, Icahn Medical Institute, Dept. of Oncological Sciences, 1425 Madison Avenue, New York, NY 10029, USA
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany.,DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, 80802 Munich, Germany
| | - Antonio Sarikas
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany.,DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, 80802 Munich, Germany
| |
Collapse
|
8
|
Beck A, Vinik Y, Shatz-Azoulay H, Isaac R, Streim S, Jona G, Boura-Halfon S, Zick Y. Otubain 2 is a novel promoter of beta cell survival as revealed by siRNA high-throughput screens of human pancreatic islets. Diabetologia 2013; 56:1317-26. [PMID: 23515685 DOI: 10.1007/s00125-013-2889-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 02/28/2013] [Indexed: 12/19/2022]
Abstract
AIMS/HYPOTHESIS Pro-inflammatory cytokines induce death of beta cells and hamper engraftment of transplanted islet mass. Our aim was to reveal novel genes involved in this process, as a platform for innovative therapeutic approaches. METHODS Small interfering RNA (siRNA) high-throughput screening (HTS) of primary human islets was employed to identify novel genes involved in cytokine-induced beta cell apoptosis. Dispersed human islets from nine human donors, treated with a combination of TNF-α, IL-1β and IFN-γ were transfected with ∼730 different siRNAs. Caspase-3/7 activity was measured, results were analysed and potential anti- and pro-apoptotic genes were identified. RESULTS Dispersed human pancreatic islets appeared to be suitable targets for performance of siRNA HTS. Using this methodology we found a number of potential pro- and anti-apoptotic target hits that have not been previously associated with pancreatic beta cell death. One such hit was the de-ubiquitinating enzyme otubain 2 (OTUB2). OTUB2 knockdown increased caspase-3/7 activity in MIN6 cells and primary human islets and inhibited insulin secretion and increased nuclear factor-κB (NF-κB) activity both under basal conditions and following cytokine treatment. CONCLUSIONS Use of dispersed human islets provides a new platform for functional HTS in a highly physiological system. Employing this technique enabled the identification of OTUB2 as a novel promoter of viability and insulin secretion in human beta cells. OTUB2 acts through the inhibition of NF-κB signalling, which is deleterious to beta cell survival. siRNA screens of human islets may therefore identify new targets, such as OTUB2, for therapeutic intervention in type 1 diabetes and islet transplantation.
Collapse
Affiliation(s)
- A Beck
- Department of Molecular Cell Biology, Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Isaac R, Boura-Halfon S, Gurevitch D, Shainskaya A, Levkovitz Y, Zick Y. Selective serotonin reuptake inhibitors (SSRIs) inhibit insulin secretion and action in pancreatic β cells. J Biol Chem 2012; 288:5682-93. [PMID: 23275337 DOI: 10.1074/jbc.m112.408641] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are antidepressants used for the treatment of mood and anxiety disorders. Here, we demonstrate that incubation (2 h) of murine islets or Min6 β cell line with the SSRIs paroxetine, fluoxetine, or sertraline inhibited insulin-induced Tyr phosphorylation of insulin receptor substrate (IRS)-2 protein and the activation of its downstream targets Akt and the ribosomal protein S6 kinase-1 (S6K1). Inhibition was dose-dependent with half-maximal effects at ∼15-20 μM. It correlated with a rapid dephosphorylation and activation of the IRS kinase GSK3β. Introduction of GSK3β siRNAs eliminated the inhibitory effects of the SSRIs. Inhibition of IRS-2 action by 30 μM SSRI was associated with a marked inhibition of glucose-stimulated insulin secretion from murine and human pancreatic islets. Secretion induced by basic secretagogues (KCl and Arg) was not affected by these drugs. Prolonged treatment (16 h) of Min6 cells with sertraline resulted in the induction of inducible nitric oxide synthase; activation of endoplasmic reticulum stress, and the initiation of the unfolded protein response, manifested by enhanced transcription of ATF4 and C/EBP homologous protein. This triggered an apoptotic process, manifested by enhanced caspase 3/7 activity, which resulted in β cell death. These findings implicate SSRIs as inhibitors of IRS protein function and insulin action through the activation of GSK3β. They further suggest that SSRIs inhibit insulin secretion; induce the unfolded protein response; activate an apoptotic process, and trigger β cell death. Given that SSRIs promote insulin resistance while inhibiting insulin secretion, these drugs might accelerate the transition from an insulin-resistant state to overt diabetes.
Collapse
Affiliation(s)
- Roi Isaac
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100 Israel
| | | | | | | | | | | |
Collapse
|
10
|
Copps KD, White MF. Regulation of insulin sensitivity by serine/threonine phosphorylation of insulin receptor substrate proteins IRS1 and IRS2. Diabetologia 2012; 55:2565-2582. [PMID: 22869320 PMCID: PMC4011499 DOI: 10.1007/s00125-012-2644-8] [Citation(s) in RCA: 690] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/23/2012] [Indexed: 12/11/2022]
Abstract
The insulin receptor substrate proteins IRS1 and IRS2 are key targets of the insulin receptor tyrosine kinase and are required for hormonal control of metabolism. Tissues from insulin-resistant and diabetic humans exhibit defects in IRS-dependent signalling, implicating their dysregulation in the initiation and progression of metabolic disease. However, IRS1 and IRS2 are regulated through a complex mechanism involving phosphorylation of >50 serine/threonine residues (S/T) within their long, unstructured tail regions. In cultured cells, insulin-stimulated kinases (including atypical PKC, AKT, SIK2, mTOR, S6K1, ERK1/2 and ROCK1) mediate feedback (autologous) S/T phosphorylation of IRS, with both positive and negative effects on insulin sensitivity. Additionally, insulin-independent (heterologous) kinases can phosphorylate IRS1/2 under basal conditions (AMPK, GSK3) or in response to sympathetic activation and lipid/inflammatory mediators, which are present at elevated levels in metabolic disease (GRK2, novel and conventional PKCs, JNK, IKKβ, mPLK). An emerging view is that the positive/negative regulation of IRS by autologous pathways is subverted/co-opted in disease by increased basal and other temporally inappropriate S/T phosphorylation. Compensatory hyperinsulinaemia may contribute strongly to this dysregulation. Here, we examine the links between altered patterns of IRS S/T phosphorylation and the emergence of insulin resistance and diabetes.
Collapse
Affiliation(s)
- K D Copps
- Howard Hughes Medical Institute, Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, CLS 16020, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - M F White
- Howard Hughes Medical Institute, Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, CLS 16020, 300 Longwood Avenue, Boston, MA, 02115, USA.
| |
Collapse
|
11
|
Kondakova IV, Spirina LV, Shashova EE, Koval' VD, Kolomiets LA, Chernysheva AL, Slonimskaia EM. [Proteasome activity in tumors of female reproductive system]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2012; 38:106-10. [PMID: 22792713 DOI: 10.1134/s106816201201013x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Proteasomes (multiproteinase protein complexes) are known to play an important role in cancer pathogenesis, however, few information about their activity in human tumor tissues is available so far. We studied chymotrypsin-like activity of proteasomes in tissues of breast cancer (BC) and endometrial cancer (EC). The chymotrypsin-like total proteasome activity and the 20S and 26S proteasome activity in malignant tissues were shown to be significantly higher in malignant tumors than in normal tissues. No increase in proteasome activity was registered with larger tumor size in both BC and EC, whereas proteasome activity was changed with respect to the extent of tumor involvement. In breast cancer tissues, significant reductions in the total and the 26S proteaome activities were observed in tumors with regional lymph node metastases as compared to tumors without metastases. In endometrial cancer tissues, the total proteasome activity and the 20S and 26S proteasome activities were increased as the depth of myometrial invasion. The data obtained indicate that the proteasome acyivity is significantly changed in the process of cancerogenesis and further study is needed to develop new additional prognostic criteria and effective anti-tumor agents in molecular-directed therapy.
Collapse
|