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Fenske RJ, Wienkes HN, Peter DC, Schaid MD, Hurley LD, Pennati A, Galipeau J, Kimple ME. Gα z-independent and -dependent Improvements With EPA Supplementation on the Early Type 1 Diabetes Phenotype of NOD Mice. J Endocr Soc 2024; 8:bvae100. [PMID: 38831864 PMCID: PMC11146416 DOI: 10.1210/jendso/bvae100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Indexed: 06/05/2024] Open
Abstract
Prostaglandin E2 (PGE2) is a key mediator of inflammation and is derived from the omega-6 polyunsaturated fatty acid, arachidonic acid (AA). In the β-cell, the PGE2 receptor, Prostaglandin EP3 receptor (EP3), is coupled to the unique heterotrimeric G protein alpha subunit, Gɑz to reduce the production of cyclic adenosine monophosphate (cAMP), a key signaling molecule that activates β-cell function, proliferation, and survival pathways. Nonobese diabetic (NOD) mice are a strong model of type 1 diabetes (T1D), and NOD mice lacking Gɑz are protected from hyperglycemia. Therefore, limiting systemic PGE2 production could potentially improve both the inflammatory and β-cell dysfunction phenotype of T1D. Here, we sought to evaluate the effect of eicosapentaenoic acid (EPA) feeding, which limits PGE2 production, on the early T1D phenotype of NOD mice in the presence and absence of Gαz. Wild-type and Gαz knockout NOD mice were fed a control or EPA-enriched diet for 12 weeks, beginning at age 4 to 5 weeks. Oral glucose tolerance, splenic T-cell populations, islet cytokine/chemokine gene expression, islet insulitis, measurements of β-cell mass, and measurements of β-cell function were quantified. EPA diet feeding and Gɑz loss independently improved different aspects of the early NOD T1D phenotype and coordinated to alter the expression of certain cytokine/chemokine genes and enhance incretin-potentiated insulin secretion. Our results shed critical light on the Gαz-dependent and -independent effects of dietary EPA enrichment and provide a rationale for future research into novel pharmacological and dietary adjuvant therapies for T1D.
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Affiliation(s)
- Rachel J Fenske
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Nutritional Sciences, University of Wisconsin–Madison, Madison, WI 53706, USA
- Clinical Research Unit, University of Wisconsin Hospitals and Clinics, Madison, WI 53792, USA
| | - Haley N Wienkes
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Darby C Peter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Michael D Schaid
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Nutritional Sciences, University of Wisconsin–Madison, Madison, WI 53706, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Liam D Hurley
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Andrea Pennati
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
- University of Wisconsin Carbone Cancer Center, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Jacques Galipeau
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
- University of Wisconsin Carbone Cancer Center, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Michelle E Kimple
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
- Department of Cell and Regenerative Biology, University of Wisconsin–Madison, Madison, WI 53705, USA
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Shapey IM, Summers A, Yiannoullou P, Fullwood C, Augustine T, Rutter MK, van Dellen D. Donor noradrenaline use is associated with better allograft survival in recipients of pancreas transplantation. Ann R Coll Surg Engl 2024; 106:19-28. [PMID: 36927080 PMCID: PMC10757882 DOI: 10.1308/rcsann.2022.0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2022] [Indexed: 03/18/2023] Open
Abstract
INTRODUCTION Outcomes following pancreas transplantation are suboptimal and better donor selection is required to improve this. Vasoactive drugs (VaD) are commonly used to correct the abnormal haemodynamics of organ donors in intensive care units. VaDs can differentially affect insulin secretion positively (dobutamine) or negatively (noradrenaline). The hypothesis was that some VaDs might induce beta-cell stress or rest and therefore impact pancreas transplant outcomes. The aim of the study was to assess relationships between VaD use and pancreas transplant graft survival. METHODS Data from the UK Transplant Registry on all pancreas transplants performed between 2004 and 2016 with complete follow-up data were included. Univariable- and multivariable-adjusted Cox regression analyses determined risks of graft failure associated with VaD use. RESULTS In 2,183 pancreas transplants, VaDs were used in the following numbers of donors: dobutamine 76 (3.5%), dopamine 84 (3.8%), adrenaline 161 (7.4%), noradrenaline 1,589 (72.8%) and vasopressin 1,219 (55.8%). In multivariable models, adjusted for covariates and the co-administration of other VaDs, noradrenaline use (vs non-use) was a strong predictor of better graft survival (hazard ratio [95% confidence interval] 0.77 [0.64-0.94], p = 0.01). CONCLUSIONS Noradrenaline use was associated with better graft survival in models adjusted for donor and recipient variables - this may be related to inhibition of pancreatic insulin secretion initiating pancreatic beta-cell 'rest'. Further research is required to replicate these findings and establish whether relationships are causal. Identification of alternative methods of inducing beta-cell rest could be valuable in improving graft outcomes.
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Affiliation(s)
- IM Shapey
- University of Manchester, UK
- Manchester University NHS Foundation Trust, UK
| | - A Summers
- Manchester University NHS Foundation Trust, UK
| | | | - C Fullwood
- University of Manchester, UK
- Manchester University NHS Foundation Trust, UK
| | - T Augustine
- Manchester University NHS Foundation Trust, UK
| | - MK Rutter
- University of Manchester, UK
- Manchester University NHS Foundation Trust, UK
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Ramanadham S, Turk J, Bhatnagar S. Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes. Compr Physiol 2023; 13:5023-5049. [PMID: 37358504 PMCID: PMC10809800 DOI: 10.1002/cphy.c220031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.
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Affiliation(s)
- Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Alabama, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
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4
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Fenske RJ, Weeks AM, Daniels M, Nall R, Pabich S, Brill AL, Peter DC, Punt M, Cox ED, Davis DB, Kimple ME. Plasma Prostaglandin E 2 Metabolite Levels Predict Type 2 Diabetes Status and One-Year Therapeutic Response Independent of Clinical Markers of Inflammation. Metabolites 2022; 12:metabo12121234. [PMID: 36557272 PMCID: PMC9783643 DOI: 10.3390/metabo12121234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Over half of patients with type 2 diabetes (T2D) are unable to achieve blood glucose targets despite therapeutic compliance, significantly increasing their risk of long-term complications. Discovering ways to identify and properly treat these individuals is a critical problem in the field. The arachidonic acid metabolite, prostaglandin E2 (PGE2), has shown great promise as a biomarker of β-cell dysfunction in T2D. PGE2 synthesis, secretion, and downstream signaling are all upregulated in pancreatic islets isolated from T2D mice and human organ donors. In these islets, preventing β-cell PGE2 signaling via a prostaglandin EP3 receptor antagonist significantly improves their glucose-stimulated and hormone-potentiated insulin secretion response. In this clinical cohort study, 167 participants, 35 non-diabetic, and 132 with T2D, were recruited from the University of Wisconsin Hospital and Clinics. At enrollment, a standard set of demographic, biometric, and clinical measurements were performed to quantify obesity status and glucose control. C reactive protein was measured to exclude acute inflammation/illness, and white cell count (WBC), erythrocyte sedimentation rate (ESR), and fasting triglycerides were used as markers of systemic inflammation. Finally, a plasma sample for research was used to determine circulating PGE2 metabolite (PGEM) levels. At baseline, PGEM levels were not correlated with WBC and triglycerides, only weakly correlated with ESR, and were the strongest predictor of T2D disease status. One year after enrollment, blood glucose management was assessed by chart review, with a clinically-relevant change in hemoglobin A1c (HbA1c) defined as ≥0.5%. PGEM levels were strongly predictive of therapeutic response, independent of age, obesity, glucose control, and systemic inflammation at enrollment. Our results provide strong support for future research in this area.
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Affiliation(s)
- Rachel J. Fenske
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Clinical Nutrition, UW Health University Hospital, Madison, WI 53705, USA
| | - Alicia M. Weeks
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Michael Daniels
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Randall Nall
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Samantha Pabich
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Allison L. Brill
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Darby C. Peter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Margaret Punt
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Elizabeth D. Cox
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53792, USA
| | - Dawn Belt Davis
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
- Correspondence: (D.B.D.); (M.E.K.); Tel.: +1-1-608-263-2443 (D.B.D.); +1-1-608-265-5627 (M.E.K.)
| | - Michelle E. Kimple
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53792, USA
- Correspondence: (D.B.D.); (M.E.K.); Tel.: +1-1-608-263-2443 (D.B.D.); +1-1-608-265-5627 (M.E.K.)
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5
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Normand C, Breton B, Salze M, Barbeau E, Mancini A, Audet M. A systematic analysis of prostaglandin E2 type 3 receptor isoform signaling reveals isoform- and species-dependent L798106 Gαz-biased agonist responses. Eur J Pharmacol 2022; 927:175043. [DOI: 10.1016/j.ejphar.2022.175043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 11/15/2022]
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Effects of Arachidonic Acid and Its Metabolites on Functional Beta-Cell Mass. Metabolites 2022; 12:metabo12040342. [PMID: 35448529 PMCID: PMC9031745 DOI: 10.3390/metabo12040342] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/06/2022] [Accepted: 04/09/2022] [Indexed: 01/26/2023] Open
Abstract
Arachidonic acid (AA) is a polyunsaturated 20-carbon fatty acid present in phospholipids in the plasma membrane. The three primary pathways by which AA is metabolized are mediated by cyclooxygenase (COX) enzymes, lipoxygenase (LOX) enzymes, and cytochrome P450 (CYP) enzymes. These three pathways produce eicosanoids, lipid signaling molecules that play roles in biological processes such as inflammation, pain, and immune function. Eicosanoids have been demonstrated to play a role in inflammatory, renal, and cardiovascular diseases as well type 1 and type 2 diabetes. Alterations in AA release or AA concentrations have been shown to affect insulin secretion from the pancreatic beta cell, leading to interest in the role of AA and its metabolites in the regulation of beta-cell function and maintenance of beta-cell mass. In this review, we discuss the metabolism of AA by COX, LOX, and CYP, the roles of these enzymes and their metabolites in beta-cell mass and function, and the possibility of targeting these pathways as novel therapies for treating diabetes.
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7
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OZITX, a pertussis toxin-like protein for occluding inhibitory G protein signalling including Gα z. Commun Biol 2022; 5:256. [PMID: 35322196 PMCID: PMC8943041 DOI: 10.1038/s42003-022-03191-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 02/17/2022] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins are the main signalling effectors for G protein-coupled receptors. Understanding the distinct functions of different G proteins is key to understanding how their signalling modulates physiological responses. Pertussis toxin, a bacterial AB5 toxin, inhibits Gαi/o G proteins and has proven useful for interrogating inhibitory G protein signalling. Pertussis toxin, however, does not inhibit one member of the inhibitory G protein family, Gαz. The role of Gαz signalling has been neglected largely due to a lack of inhibitors. Recently, the identification of another Pertussis-like AB5 toxin was described. Here we show that this toxin, that we call OZITX, specifically inhibits Gαi/o and Gαz G proteins and that expression of the catalytic S1 subunit is sufficient for this inhibition. We identify mutations that render Gα subunits insensitive to the toxin that, in combination with the toxin, can be used to interrogate the signalling of each inhibitory Gα G protein. A recently identified pertussis toxin-like AB5 toxin, OZITX, is found to inhibit Gαi/o and Gαz G proteins. In combination with directed mutations, it is a useful tool for interrogating Gαi/o/z G protein subunits individually.
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8
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Wisinski JA, Reuter A, Peter DC, Schaid MD, Fenske RJ, Kimple ME. Prostaglandin EP3 receptor signaling is required to prevent insulin hypersecretion and metabolic dysfunction in a non-obese mouse model of insulin resistance. Am J Physiol Endocrinol Metab 2021; 321:E479-E489. [PMID: 34229444 PMCID: PMC8560379 DOI: 10.1152/ajpendo.00051.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When homozygous for the LeptinOb mutation (Ob), Black-and-Tan Brachyury (BTBR) mice become morbidly obese and severely insulin resistant, and by 10 wk of age, frankly diabetic. Previous work has shown prostaglandin EP3 receptor (EP3) expression and activity is upregulated in islets from BTBR-Ob mice as compared with lean controls, actively contributing to their β-cell dysfunction. In this work, we aimed to test the impact of β-cell-specific EP3 loss on the BTBR-Ob phenotype by crossing Ptger3 floxed mice with the rat insulin promoter (RIP)-CreHerr driver strain. Instead, germline recombination of the floxed allele in the founder mouse-an event whose prevalence we identified as directly associated with underlying insulin resistance of the background strain-generated a full-body knockout. Full-body EP3 loss provided no diabetes protection to BTBR-Ob mice but, unexpectedly, significantly worsened BTBR-lean insulin resistance and glucose tolerance. This in vivo phenotype was not associated with changes in β-cell fractional area or markers of β-cell replication ex vivo. Instead, EP3-null BTBR-lean islets had essentially uncontrolled insulin hypersecretion. The selective upregulation of constitutively active EP3 splice variants in islets from young, lean BTBR mice as compared with C57BL/6J, where no phenotype of EP3 loss has been observed, provides a potential explanation for the hypersecretion phenotype. In support of this, high islet EP3 expression in Balb/c females versus Balb/c males was fully consistent with their sexually dimorphic metabolic phenotype after loss of EP3-coupled Gαz protein. Taken together, our findings provide a new dimension to the understanding of EP3 as a critical brake on insulin secretion.NEW & NOTEWORTHY Islet prostaglandin EP3 receptor (EP3) signaling is well known as upregulated in the pathophysiological conditions of type 2 diabetes, contributing to β-cell dysfunction. Unexpected findings in mouse models of non-obese insulin sensitivity and resistance provide a new dimension to our understanding of EP3 as a key modulator of insulin secretion. A previously unknown relationship between mouse insulin resistance and the penetrance of rat insulin promoter-driven germline floxed allele recombination is critical to consider when creating β-cell-specific knockouts.
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Affiliation(s)
- Jaclyn A Wisinski
- Department of Biology, University of Wisconsin-LaCrosse, La Crosse, Wisconsin
| | - Austin Reuter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
| | - Darby C Peter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
| | - Michael D Schaid
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
- Interdepartmental Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Rachel J Fenske
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Interdepartmental Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Michelle E Kimple
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
- Interdepartmental Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin
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9
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Pancreatic Islets Exhibit Dysregulated Adaptation of Insulin Secretion after Chronic Epinephrine Exposure. Curr Issues Mol Biol 2021; 43:240-250. [PMID: 34071501 PMCID: PMC8929152 DOI: 10.3390/cimb43010020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 01/11/2023] Open
Abstract
Chronic adrenergic stimulation is the dominant factor in impairment of the β-cell function. Sustained adrenergic exposure generates dysregulated insulin secretion in fetal sheep. Similar results have been shown in Min6 under the elevated epinephrine condition, but impairments after adrenergic removal are still unknown and a high rate of proliferation in Min6 has been ignored. Therefore, we incubated primary rats' islets with half maximal inhibitory concentrations of epinephrine for three days, then determined their insulin secretion responsiveness and related signals two days after removal of adrenaline via radioimmunoassay and qPCR. Insulin secretion was not different between the exposure group (1.07 ± 0.04 ng/islet/h) and control (1.23 ± 0.17 ng/islet/h), but total islet insulin content after treatment (5.46 ± 0.87 ng/islet/h) was higher than control (3.17 ± 0.22 ng/islet/h, p < 0.05), and the fractional insulin release was 36% (p < 0.05) lower after the treatment. Meanwhile, the mRNA expression of Gαs, Gαz and Gβ1-2 decreased by 42.8% 19.4% and 24.8%, respectively (p < 0.05). Uncoupling protein 2 (Ucp2), sulphonylurea receptor 1 (Sur1) and superoxide dismutase 2 (Sod2) were significantly reduced (38.5%, 23.8% and 53.8%, p < 0.05). Chronic adrenergic exposure could impair insulin responsiveness in primary pancreatic islets. Decreased G proteins and Sur1 expression affect the regulation of insulin secretion. In conclusion, the sustained under-expression of Ucp2 and Sod2 may further change the function of β-cell, which helps to understand the long-term adrenergic adaptation of pancreatic β-cell.
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10
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Wang W, Zhong X, Guo J. Role of 2‑series prostaglandins in the pathogenesis of type 2 diabetes mellitus and non‑alcoholic fatty liver disease (Review). Int J Mol Med 2021; 47:114. [PMID: 33907839 PMCID: PMC8083810 DOI: 10.3892/ijmm.2021.4947] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/24/2021] [Indexed: 02/06/2023] Open
Abstract
Nowadays, metabolic syndromes are emerging as global epidemics, whose incidence are increasing annually. However, the efficacy of therapy does not increase proportionately with the increased morbidity. Type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) are two common metabolic syndromes that are closely associated. The pathogenic mechanisms of T2DM and NAFLD have been studied, and it was revealed that insulin resistance, hyperglycemia, hepatic lipid accumulation and inflammation markedly contribute to the development of these two diseases. The 2-series prostaglandins (PGs), a subgroup of eicosanoids, including PGD2, PGE2, PGF2α and PGI2, are converted from arachidonic acid catalyzed by the rate-limiting enzymes cyclooxygenases (COXs). Considering their wide distribution in almost every tissue, 2-series PG pathways exert complex and interlinked effects in mediating pancreatic β-cell function and proliferation, insulin sensitivity, fat accumulation and lipolysis, as well as inflammatory processes. Previous studies have revealed that metabolic disturbances, such as hyperglycemia and hyperlipidemia, can be improved by treatment with COX inhibitors. At present, an accumulating number of studies have focused on the roles of 2-series PGs and their metabolites in the pathogenesis of metabolic syndromes, particularly T2DM and NAFLD. In the present review, the role of 2-series PGs in the highly intertwined pathogenic mechanisms of T2DM and NAFLD was discussed, and important therapeutic strategies based on targeting 2-series PG pathways in T2DM and NAFLD treatment were provided.
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Affiliation(s)
- Weixuan Wang
- Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong 510006, P.R. China
| | - Xin Zhong
- Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong 510006, P.R. China
| | - Jiao Guo
- Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong 510006, P.R. China
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11
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Sandhu HK, Neuman JC, Schaid MD, Davis SE, Connors KM, Challa R, Guthery E, Fenske RJ, Patibandla C, Breyer RM, Kimple ME. Rat prostaglandin EP3 receptor is highly promiscuous and is the sole prostanoid receptor family member that regulates INS-1 (832/3) cell glucose-stimulated insulin secretion. Pharmacol Res Perspect 2021; 9:e00736. [PMID: 33694300 PMCID: PMC7947324 DOI: 10.1002/prp2.736] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/27/2021] [Accepted: 01/27/2021] [Indexed: 12/19/2022] Open
Abstract
Chronic elevations in fatty acid metabolites termed prostaglandins can be found in circulation and in pancreatic islets from mice or humans with diabetes and have been suggested as contributing to the β‐cell dysfunction of the disease. Two‐series prostaglandins bind to a family of G‐protein‐coupled receptors, each with different biochemical and pharmacological properties. Prostaglandin E receptor (EP) subfamily agonists and antagonists have been shown to influence β‐cell insulin secretion, replication, and/or survival. Here, we define EP3 as the sole prostanoid receptor family member expressed in a rat β‐cell‐derived line that regulates glucose‐stimulated insulin secretion. Several other agonists classically understood as selective for other prostanoid receptor family members also reduce glucose‐stimulated insulin secretion, but these effects are only observed at relatively high concentrations, and, using a well‐characterized EP3‐specific antagonist, are mediated solely by cross‐reactivity with rat EP3. Our findings confirm the critical role of EP3 in regulating β‐cell function, but are also of general interest, as many agonists supposedly selective for other prostanoid receptor family members are also full and efficacious agonists of EP3. Therefore, care must be taken when interpreting experimental results from cells or cell lines that also express EP3.
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Affiliation(s)
- Harpreet K Sandhu
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Joshua C Neuman
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.,Interdepartmental Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael D Schaid
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.,Interdepartmental Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Sarah E Davis
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kelsey M Connors
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Romith Challa
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Erin Guthery
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Rachel J Fenske
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.,Interdepartmental Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Chinmai Patibandla
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Richard M Breyer
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.,Interdepartmental Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA.,Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, USA
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12
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Schaid MD, Green CL, Peter DC, Gallagher SJ, Guthery E, Carbajal KA, Harrington JM, Kelly GM, Reuter A, Wehner ML, Brill AL, Neuman JC, Lamming DW, Kimple ME. Agonist-independent Gα z activity negatively regulates beta-cell compensation in a diet-induced obesity model of type 2 diabetes. J Biol Chem 2020; 296:100056. [PMID: 33172888 PMCID: PMC7948463 DOI: 10.1074/jbc.ra120.015585] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/04/2020] [Accepted: 11/10/2020] [Indexed: 12/17/2022] Open
Abstract
The inhibitory G protein alpha-subunit (Gαz) is an important modulator of beta-cell function. Full-body Gαz-null mice are protected from hyperglycemia and glucose intolerance after long-term high-fat diet (HFD) feeding. In this study, at a time point in the feeding regimen where WT mice are only mildly glucose intolerant, transcriptomics analyses reveal islets from HFD-fed Gαz KO mice have a dramatically altered gene expression pattern as compared with WT HFD-fed mice, with entire gene pathways not only being more strongly upregulated or downregulated versus control-diet fed groups but actually reversed in direction. Genes involved in the “pancreatic secretion” pathway are the most strongly differentially regulated: a finding that correlates with enhanced islet insulin secretion and decreased glucagon secretion at the study end. The protection of Gαz-null mice from HFD-induced diabetes is beta-cell autonomous, as beta cell–specific Gαz-null mice phenocopy the full-body KOs. The glucose-stimulated and incretin-potentiated insulin secretion response of islets from HFD-fed beta cell–specific Gαz-null mice is significantly improved as compared with islets from HFD-fed WT controls, which, along with no impact of Gαz loss or HFD feeding on beta-cell proliferation or surrogates of beta-cell mass, supports a secretion-specific mechanism. Gαz is coupled to the prostaglandin EP3 receptor in pancreatic beta cells. We confirm the EP3γ splice variant has both constitutive and agonist-sensitive activity to inhibit cAMP production and downstream beta-cell function, with both activities being dependent on the presence of beta-cell Gαz.
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Affiliation(s)
- Michael D Schaid
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Cara L Green
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Darby C Peter
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Shannon J Gallagher
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Erin Guthery
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Kathryn A Carbajal
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Jeffrey M Harrington
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Grant M Kelly
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Austin Reuter
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Molly L Wehner
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Allison L Brill
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Joshua C Neuman
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Dudley W Lamming
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Michelle E Kimple
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA; Department of Cell and Regenerative Biology, University of Wisconsin- Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
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13
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Amior L, Srivastava R, Nano R, Bertuzzi F, Melloul D. The role of Cox-2 and prostaglandin E 2 receptor EP3 in pancreatic β-cell death. FASEB J 2019; 33:4975-4986. [PMID: 30629897 DOI: 10.1096/fj.201801823r] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Elevated levels of lipids, in particular saturated fatty acids, are known to be associated with type 2 diabetes (T2D) and to have a negative effect on β-cell function and survival. We bring new evidence indicating that palmitate up-regulates cyclooxygenase-2 (COX-2) expression levels in human islets and in MIN6 β cells, and that it is elevated in islets isolated from T2D donors. Both small interfering specific cyclooxygenase-2 small interfering RNA (siRNA) or the COX-2 inhibitor celecoxib significantly inhibited apoptosis induced by palmitate. Prostaglandin E2 (PGE2), the predominant product of COX-2 enzymatic activity, activates membrane receptors, which are members of the GPCR-family (EP1-EP4). In the present study, elevated expression of the PGE2 receptor subtype 3 (EP3) receptor was observed in β cells exposed to palmitate and in islets from individuals with T2D. Down-regulation of the pathway using EP3 siRNA or the specific L-798,106 antagonist markedly decreased the levels of palmitate-induced apoptosis. Altogether, our data put forward the COX-2-PGE2-EP3 pathway as one of the mediators of palmitate-induced apoptosis in β-cells.-Amior, L., Srivastava, R., Nano, R., Bertuzzi, F., Melloul, D. The role of Cox-2 and prostaglandin E2 receptor EP3 in pancreatic β-cell death.
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Affiliation(s)
- Livnat Amior
- Department of Endocrinology, Hadassah University Hospital, Jerusalem, Israel; and
| | - Rohit Srivastava
- Department of Endocrinology, Hadassah University Hospital, Jerusalem, Israel; and
| | - Rita Nano
- Diabetes Research Institute, Instituto di Ricovero e Cura a Carattere Scientifico San Raffaele Scientific Institute, Milan, Italy
| | - Federico Bertuzzi
- Diabetes Research Institute, Instituto di Ricovero e Cura a Carattere Scientifico San Raffaele Scientific Institute, Milan, Italy
| | - Danielle Melloul
- Department of Endocrinology, Hadassah University Hospital, Jerusalem, Israel; and
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14
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Fenske RJ, Kimple ME. Targeting dysfunctional beta-cell signaling for the potential treatment of type 1 diabetes mellitus. Exp Biol Med (Maywood) 2018; 243:586-591. [PMID: 29504478 DOI: 10.1177/1535370218761662] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Since its discovery and purification by Frederick Banting in 1921, exogenous insulin has remained almost the sole therapy for type 1 diabetes mellitus. While insulin alleviates the primary dysfunction of the disease, many other aspects of the pathophysiology of type 1 diabetes mellitus are unaffected. Research aimed towards the discovery of novel type 1 diabetes mellitus therapeutics targeting different cell signaling pathways is gaining momentum. The focus of these efforts has been almost entirely on the impact of immunomodulatory drugs, particularly those that have already received FDA-approval for other autoimmune diseases. However, these drugs can often have severe side effects, while also putting already immunocompromised individuals at an increased risk for other infections. Potential therapeutic targets in the insulin-producing beta-cell have been largely ignored by the type 1 diabetes mellitus field, save the glucagon-like peptide 1 receptor. While there is preliminary evidence to support the clinical exploration of glucagon-like peptide 1 receptor-based drugs as type 1 diabetes mellitus adjuvant therapeutics, there is a vast space for other putative therapeutic targets to be explored. The alpha subunit of the heterotrimeric Gz protein (Gαz) has been shown to promote beta-cell inflammation, dysfunction, death, and failure to replicate in the context of diabetes in a number of mouse models. Genetic loss of Gαz or inhibition of the Gαz signaling pathway through dietary interventions is protective against the development of insulitis and hyperglycemia. The multifaceted effects of Gαz in regards to beta-cell health in the context of diabetes make it an ideal therapeutic target for further study. It is our belief that a low-risk, effective therapy for type 1 diabetes mellitus will involve a multidimensional approach targeting a number of regulatory systems, not the least of which is the insulin-producing beta-cell. Impact statement The expanding investigation of beta-cell therapeutic targets for the treatment and prevention of type 1 diabetes mellitus is fundamentally relevant and timely. This review summarizes the overall scope of research into novel type 1 diabetes mellitus therapeutics, highlighting weaknesses or caveats in current clinical trials as well as describing potential new targets to pursue. More specifically, signaling proteins that act as modulators of beta-cell function, survival, and replication, as well as immune infiltration may need to be targeted to develop the most efficient pharmaceutical interventions for type 1 diabetes mellitus. One such beta-cell signaling pathway, mediated by the alpha subunit of the heterotrimeric Gz protein (Gαz), is discussed in more detail. The work described here will be critical in moving the field forward as it emphasizes the central role of the beta-cell in type 1 diabetes mellitus disease pathology.
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Affiliation(s)
- Rachel J Fenske
- 1 Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.,2 Department of Medicine, Division of Endocrinology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA.,3 Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
| | - Michelle E Kimple
- 1 Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.,2 Department of Medicine, Division of Endocrinology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA.,3 Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA.,4 Department of Cell and Regenerative Biology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
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15
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Schaid MD, Wisinski JA, Kimple ME. The EP3 Receptor/G z Signaling Axis as a Therapeutic Target for Diabetes and Cardiovascular Disease. AAPS J 2017; 19:1276-1283. [PMID: 28584908 PMCID: PMC7934137 DOI: 10.1208/s12248-017-0097-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 05/05/2017] [Indexed: 12/25/2022] Open
Abstract
Cardiovascular disease is a common co-morbidity found with obesity-linked type 2 diabetes. Current pharmaceuticals for these two diseases treat each of them separately. Yet, diabetes and cardiovascular disease share molecular signaling pathways that are increasingly being understood to contribute to disease pathophysiology, particularly in pre-clinical models. This review will focus on one such signaling pathway: that mediated by the G protein-coupled receptor, Prostaglandin E2 Receptor 3 (EP3), and its associated G protein in the insulin-secreting beta-cell and potentially the platelet, Gz. The EP3/Gz signaling axis may hold promise as a dual target for type 2 diabetes and cardiovascular disease.
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Affiliation(s)
- Michael D Schaid
- Interdisciplinary Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, 4148 UW Medical Foundation Centennial Building, 1685 Highland Ave, Madison, Wisconsin, 53705, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA
| | - Jaclyn A Wisinski
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA
- Department of Medicine, Division of Endocrinology, School of Medicine and Public Health, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Michelle E Kimple
- Interdisciplinary Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, 4148 UW Medical Foundation Centennial Building, 1685 Highland Ave, Madison, Wisconsin, 53705, USA.
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA.
- Department of Medicine, Division of Endocrinology, School of Medicine and Public Health, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
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Affiliation(s)
- R Paul Robertson
- Pacific Northwest Diabetes Research Institute and Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Seattle, WA, and Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN
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17
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Fenske RJ, Cadena MT, Harenda QE, Wienkes HN, Carbajal K, Schaid MD, Laundre E, Brill AL, Truchan NA, Brar H, Wisinski J, Cai J, Graham TE, Engin F, Kimple ME. The Inhibitory G Protein α-Subunit, Gαz, Promotes Type 1 Diabetes-Like Pathophysiology in NOD Mice. Endocrinology 2017; 158:1645-1658. [PMID: 28419211 PMCID: PMC5460933 DOI: 10.1210/en.2016-1700] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 04/11/2017] [Indexed: 01/23/2023]
Abstract
The α-subunit of the heterotrimeric Gz protein, Gαz, promotes β-cell death and inhibits β-cell replication when pancreatic islets are challenged by stressors. Thus, we hypothesized that loss of Gαz protein would preserve functional β-cell mass in the nonobese diabetic (NOD) model, protecting from overt diabetes. We saw that protection from diabetes was robust and durable up to 35 weeks of age in Gαz knockout mice. By 17 weeks of age, Gαz-null NOD mice had significantly higher diabetes-free survival than wild-type littermates. Islets from these mice had reduced markers of proinflammatory immune cell infiltration on both the histological and transcript levels and secreted more insulin in response to glucose. Further analyses of pancreas sections revealed significantly fewer terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL)-positive β-cells in Gαz-null islets despite similar immune infiltration in control mice. Islets from Gαz-null mice also exhibited a higher percentage of Ki-67-positive β-cells, a measure of proliferation, even in the presence of immune infiltration. Finally, β-cell-specific Gαz-null mice phenocopy whole-body Gαz-null mice in their protection from developing hyperglycemia after streptozotocin administration, supporting a β-cell-centric role for Gαz in diabetes pathophysiology. We propose that Gαz plays a key role in β-cell signaling that becomes dysfunctional in the type 1 diabetes setting, accelerating the death of β-cells, which promotes further accumulation of immune cells in the pancreatic islets, and inhibiting a restorative proliferative response.
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MESH Headings
- Animals
- Apoptosis/genetics
- Blood Glucose/metabolism
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Female
- GTP-Binding Protein alpha Subunits/genetics
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, Knockout
- Mice, Transgenic
- Streptozocin
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Affiliation(s)
- Rachel J. Fenske
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Mark T. Cadena
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Quincy E. Harenda
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Haley N. Wienkes
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Kathryn Carbajal
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Michael D. Schaid
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Erin Laundre
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Allison L. Brill
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Nathan A. Truchan
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Harpreet Brar
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Jaclyn Wisinski
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Jinjin Cai
- Molecular Medicine Program, Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, Department of Nutrition, and Department of Biological Chemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
- George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah 84112
| | - Timothy E. Graham
- Molecular Medicine Program, Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, Department of Nutrition, and Department of Biological Chemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
- George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah 84112
| | - Feyza Engin
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Michelle E. Kimple
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53705
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18
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Carboneau BA, Allan JA, Townsend SE, Kimple ME, Breyer RM, Gannon M. Opposing effects of prostaglandin E 2 receptors EP3 and EP4 on mouse and human β-cell survival and proliferation. Mol Metab 2017; 6:548-559. [PMID: 28580285 PMCID: PMC5444094 DOI: 10.1016/j.molmet.2017.04.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVE Hyperglycemia and systemic inflammation, hallmarks of Type 2 Diabetes (T2D), can induce the production of the inflammatory signaling molecule Prostaglandin E2 (PGE2) in islets. The effects of PGE2 are mediated by its four receptors, E-Prostanoid Receptors 1-4 (EP1-4). EP3 and EP4 play opposing roles in many cell types due to signaling through different G proteins, Gi and GS, respectively. We previously found that EP3 and EP4 expression are reciprocally regulated by activation of the FoxM1 transcription factor, which promotes β-cell proliferation and survival. Our goal was to determine if EP3 and EP4 regulate β-cell proliferation and survival and, if so, to elucidate the downstream signaling mechanisms. METHODS β-cell proliferation was assessed in mouse and human islets ex vivo treated with selective agonists and antagonists for EP3 (sulprostone and DG-041, respectively) and EP4 (CAY10598 and L-161,982, respectively). β-cell survival was measured in mouse and human islets treated with the EP3- and EP4-selective ligands in conjunction with a cytokine cocktail to induce cell death. Changes in gene expression and protein phosphorylation were analyzed in response to modulation of EP3 and EP4 activity in mouse islets. RESULTS Blockade of EP3 enhanced β-cell proliferation in young, but not old, mouse islets in part through phospholipase C (PLC)-γ1 activity. Blocking EP3 also increased human β-cell proliferation. EP4 modulation had no effect on ex vivo proliferation alone. However, blockade of EP3 in combination with activation of EP4 enhanced human, but not mouse, β-cell proliferation. In both mouse and human islets, EP3 blockade or EP4 activation enhanced β-cell survival in the presence of cytokines. EP4 acts in a protein kinase A (PKA)-dependent manner to increase mouse β-cell survival. In addition, the positive effects of FoxM1 activation on β-cell survival are inhibited by EP3 and dependent on EP4 signaling. CONCLUSIONS Our results identify EP3 and EP4 as novel regulators of β-cell proliferation and survival in mouse and human islets ex vivo.
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Key Words
- COX-2, cyclooxygenase-2
- Cell death
- DAG, diacylglycerol
- EP1-4, E-Prostanoid Receptors 1-4
- GPCR, G protein-coupled receptor
- IP3, inositol 1,4,5-trisphosphate
- PGE2, prostaglandin E2
- PKA, protein kinase A
- PL, placental lactogen
- PLC, phospholipase C
- PT, pertussis toxin
- Pancreatic β-cell
- Proliferation
- Prostaglandin E2
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Affiliation(s)
- Bethany A Carboneau
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Jack A Allan
- School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Shannon E Townsend
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Richard M Breyer
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Maureen Gannon
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
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19
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Neuman JC, Fenske RJ, Kimple ME. Dietary polyunsaturated fatty acids and their metabolites: Implications for diabetes pathophysiology, prevention, and treatment. NUTRITION AND HEALTHY AGING 2017; 4:127-140. [PMID: 28447067 PMCID: PMC5391679 DOI: 10.3233/nha-160004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Affiliation(s)
- Joshua C. Neuman
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Rachel J. Fenske
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Michelle E. Kimple
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Department of Medicine, Division of Endocrinology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
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20
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Carboneau BA, Breyer RM, Gannon M. Regulation of pancreatic β-cell function and mass dynamics by prostaglandin signaling. J Cell Commun Signal 2017; 11:105-116. [PMID: 28132118 DOI: 10.1007/s12079-017-0377-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/16/2017] [Indexed: 01/09/2023] Open
Abstract
Prostaglandins (PGs) are signaling lipids derived from arachidonic acid (AA), which is metabolized by cyclooxygenase (COX)-1 or 2 and class-specific synthases to generate PGD2, PGE2, PGF2α, PGI2 (prostacyclin), and thromboxane A2. PGs signal through G-protein coupled receptors (GPCRs) and are important modulators of an array of physiological functions, including systemic inflammation and insulin secretion from pancreatic islets. The role of PGs in β-cell function has been an active area of interest, beginning in the 1970s. Early studies demonstrated that PGE2 inhibits glucose-stimulated insulin secretion (GSIS), although more recent studies have questioned this inhibitory action of PGE2. The PGE2 receptor EP3 and one of the G-proteins that couples to EP3, GαZ, have been identified as negative regulators of β-cell proliferation and survival. Conversely, PGI2 and its receptor, IP, play a positive role in the β-cell by enhancing GSIS and preserving β-cell mass in response to the β-cell toxin streptozotocin (STZ). In comparison to PGE2 and PGI2, little is known about the function of the remaining PGs within islets. In this review, we discuss the roles of PGs, particularly PGE2 and PGI2, PG receptors, and downstream signaling events that alter β-cell function and regulation of β-cell mass.
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Affiliation(s)
- Bethany A Carboneau
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Richard M Breyer
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, USA
| | - Maureen Gannon
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA. .,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA. .,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA. .,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA. .,Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA.
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21
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Zhao Y, Fang Q, Straub SG, Lindau M, Sharp GWG. Prostaglandin E1 inhibits endocytosis in the β-cell endocytosis. J Endocrinol 2016; 229:287-94. [PMID: 27068696 DOI: 10.1530/joe-15-0435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/11/2016] [Indexed: 12/23/2022]
Abstract
Prostaglandins inhibit insulin secretion in a manner similar to that of norepinephrine (NE) and somatostatin. As NE inhibits endocytosis as well as exocytosis, we have now examined the modulation of endocytosis by prostaglandin E1 (PGE1). Endocytosis following exocytosis was recorded by whole-cell patch clamp capacitance measurements in INS-832/13 cells. Prolonged depolarizing pulses producing a high level of Ca(2+) influx were used to stimulate maximal exocytosis and to deplete the readily releasable pool (RRP) of granules. This high Ca(2+) influx eliminates the inhibitory effect of PGE1 on exocytosis and allows specific characterization of the inhibitory effect of PGE1 on the subsequent compensatory endocytosis. After stimulating exocytosis, endocytosis was apparent under control conditions but was inhibited by PGE1 in a Pertussis toxin-sensitive (PTX)-insensitive manner. Dialyzing a synthetic peptide mimicking the C-terminus of the α-subunit of the heterotrimeric G-protein Gz into the cells blocked the inhibition of endocytosis by PGE1, whereas a control-randomized peptide was without effect. These results demonstrate that PGE1 inhibits endocytosis and Gz mediates the inhibition.
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Affiliation(s)
- Ying Zhao
- Department of Molecular MedicineCornell University, Ithaca, New York, USA School of Applied and Engineering PhysicsCornell University, Ithaca, New York, USA Laboratory for Nanoscale Cell BiologyMax-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Qinghua Fang
- School of Applied and Engineering PhysicsCornell University, Ithaca, New York, USA Laboratory for Nanoscale Cell BiologyMax-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Susanne G Straub
- Department of Molecular MedicineCornell University, Ithaca, New York, USA
| | - Manfred Lindau
- School of Applied and Engineering PhysicsCornell University, Ithaca, New York, USA Laboratory for Nanoscale Cell BiologyMax-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Geoffrey W G Sharp
- Department of Molecular MedicineCornell University, Ithaca, New York, USA
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22
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Brill AL, Wisinski JA, Cadena MT, Thompson MF, Fenske RJ, Brar HK, Schaid MD, Pasker RL, Kimple ME. Synergy Between Gαz Deficiency and GLP-1 Analog Treatment in Preserving Functional β-Cell Mass in Experimental Diabetes. Mol Endocrinol 2016; 30:543-56. [PMID: 27049466 DOI: 10.1210/me.2015-1164] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A defining characteristic of type 1 diabetes mellitus (T1DM) pathophysiology is pancreatic β-cell death and dysfunction, resulting in insufficient insulin secretion to properly control blood glucose levels. Treatments that promote β-cell replication and survival, thus reversing the loss of β-cell mass, while also preserving β-cell function, could lead to a real cure for T1DM. The α-subunit of the heterotrimeric Gz protein, Gαz, is a tonic negative regulator of adenylate cyclase and downstream cAMP production. cAMP is one of a few identified signaling molecules that can simultaneously have a positive impact on pancreatic islet β-cell proliferation, survival, and function. The purpose of our study was to determine whether mice lacking Gαz might be protected, at least partially, from β-cell loss and dysfunction after streptozotocin treatment. We also aimed to determine whether Gαz might act in concert with an activator of the cAMP-stimulatory glucagon-like peptide 1 receptor, exendin-4 (Ex4). Without Ex4 treatment, Gαz-null mice still developed hyperglycemia, albeit delayed. The same finding held true for wild-type mice treated with Ex4. With Ex4 treatment, Gαz-null mice were protected from developing severe hyperglycemia. Immunohistological studies performed on pancreas sections and in vitro apoptosis, cytotoxicity, and survival assays demonstrated a clear effect of Gαz signaling on pancreatic β-cell replication and death; β-cell function was also improved in Gαz-null islets. These data support our hypothesis that a combination of therapies targeting both stimulatory and inhibitory pathways will be more effective than either alone at protecting, preserving, and possibly regenerating β-cell mass and function in T1DM.
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Affiliation(s)
- Allison L Brill
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Jaclyn A Wisinski
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Mark T Cadena
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Mary F Thompson
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Rachel J Fenske
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Harpreet K Brar
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Michael D Schaid
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Renee L Pasker
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Michelle E Kimple
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
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23
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Neuman JC, Truchan NA, Joseph JW, Kimple ME. A method for mouse pancreatic islet isolation and intracellular cAMP determination. J Vis Exp 2014:e50374. [PMID: 24998772 DOI: 10.3791/50374] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing prevalence of diabetes, both immune-mediated type 1 and obesity-linked type 2, studies aimed at delineating diabetes pathophysiology and therapeutic mechanisms are of critical importance. The β-cells of the pancreatic islets of Langerhans are responsible for appropriately secreting insulin in response to elevated blood glucose concentrations. In addition to glucose and other nutrients, the β-cells are also stimulated by specific hormones, termed incretins, which are secreted from the gut in response to a meal and act on β-cell receptors that increase the production of intracellular cyclic adenosine monophosphate (cAMP). Decreased β-cell function, mass, and incretin responsiveness are well-understood to contribute to the pathophysiology of type 2 diabetes, and are also being increasingly linked with type 1 diabetes. The present mouse islet isolation and cAMP determination protocol can be a tool to help delineate mechanisms promoting disease progression and therapeutic interventions, particularly those that are mediated by the incretin receptors or related receptors that act through modulation of intracellular cAMP production. While only cAMP measurements will be described, the described islet isolation protocol creates a clean preparation that also allows for many other downstream applications, including glucose stimulated insulin secretion, [3(H)]-thymidine incorporation, protein abundance, and mRNA expression.
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Affiliation(s)
- Joshua C Neuman
- Department of Nutrional Sciences, University of Wisconsin-Madison
| | - Nathan A Truchan
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison
| | | | - Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison;
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24
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Kimple ME, Neuman JC, Linnemann AK, Casey PJ. Inhibitory G proteins and their receptors: emerging therapeutic targets for obesity and diabetes. Exp Mol Med 2014; 46:e102. [PMID: 24946790 PMCID: PMC4081554 DOI: 10.1038/emm.2014.40] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/10/2014] [Accepted: 02/17/2014] [Indexed: 12/21/2022] Open
Abstract
The worldwide prevalence of obesity is steadily increasing, nearly doubling between 1980 and 2008. Obesity is often associated with insulin resistance, a major risk factor for type 2 diabetes mellitus (T2DM): a costly chronic disease and serious public health problem. The underlying cause of T2DM is a failure of the beta cells of the pancreas to continue to produce enough insulin to counteract insulin resistance. Most current T2DM therapeutics do not prevent continued loss of insulin secretion capacity, and those that do have the potential to preserve beta cell mass and function are not effective in all patients. Therefore, developing new methods for preventing and treating obesity and T2DM is very timely and of great significance. There is now considerable literature demonstrating a link between inhibitory guanine nucleotide-binding protein (G protein) and G protein-coupled receptor (GPCR) signaling in insulin-responsive tissues and the pathogenesis of obesity and T2DM. These studies are suggesting new and emerging therapeutic targets for these conditions. In this review, we will discuss inhibitory G proteins and GPCRs that have primary actions in the beta cell and other peripheral sites as therapeutic targets for obesity and T2DM, improving satiety, insulin resistance and/or beta cell biology.
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Affiliation(s)
- Michelle E Kimple
- Department of Medicine-Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua C Neuman
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Amelia K Linnemann
- Department of Medicine-Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Patrick J Casey
- Duke University Medical Center Department of Pharmacology and Cancer Biology, Durham, NC, USA
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25
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Straub SG, Sharp GWG. Evolving insights regarding mechanisms for the inhibition of insulin release by norepinephrine and heterotrimeric G proteins. Am J Physiol Cell Physiol 2012; 302:C1687-98. [PMID: 22492651 DOI: 10.1152/ajpcell.00282.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Norepinephrine has for many years been known to have three major effects on the pancreatic β-cell which lead to the inhibition of insulin release. These are activation of K(+) channels to hyperpolarize the cell and prevent the gating of voltage-dependent Ca(2+) channels that increase intracellular Ca(2+) concentration ([Ca(2+)](i)) and trigger release; inhibition of adenylyl cyclases, thus preventing the augmentation of stimulated insulin release by cyclic AMP; and a "distal" effect that occurs downstream of increased [Ca(2+)](i) to inhibit exocytosis. All three are mediated by the pertussis toxin (PTX)-sensitive heterotrimeric Gi and Go proteins. The distal inhibitory effect on exocytosis is now known to be due to the binding of G protein βγ subunits to the synaptosomal-associated protein of 25 kDa (SNAP-25) on the soluble NSF attachment protein receptor (SNARE) complex. Recent studies have uncovered two more actions of norepinephrine on the β-cell: 1) retardation of the refilling of the readily releasable granule pool after it has been discharged, an action that is mediated by Gαi(1) and/or Gαi(2); and 2) inhibition of endocytosis that is mediated by Gz. Of importance also are new findings that Gαo regulates the number of docked granules in the β-cell, and that Gαo(2) maintains a tonic inhibitory influence on secretion. The latter provides another explanation as to why PTX, which blocks the effect of Gαo(2), was initially called "islet activating protein." Finally, there is clear evidence that overexpression of α(2A)-adrenergic receptors in β-cells can cause type 2 diabetes.
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Affiliation(s)
- Susanne G Straub
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853-6401, USA
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26
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Kimple ME, Moss JB, Brar HK, Rosa TC, Truchan NA, Pasker RL, Newgard CB, Casey PJ. Deletion of GαZ protein protects against diet-induced glucose intolerance via expansion of β-cell mass. J Biol Chem 2012; 287:20344-55. [PMID: 22457354 DOI: 10.1074/jbc.m112.359745] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Insufficient plasma insulin levels caused by deficits in both pancreatic β-cell function and mass contribute to the pathogenesis of type 2 diabetes. This loss of insulin-producing capacity is termed β-cell decompensation. Our work is focused on defining the role(s) of guanine nucleotide-binding protein (G protein) signaling pathways in regulating β-cell decompensation. We have previously demonstrated that the α-subunit of the heterotrimeric G(z) protein, Gα(z), impairs insulin secretion by suppressing production of cAMP. Pancreatic islets from Gα(z)-null mice also exhibit constitutively increased cAMP production and augmented glucose-stimulated insulin secretion, suggesting that Gα(z) is a tonic inhibitor of adenylate cyclase, the enzyme responsible for the conversion of ATP to cAMP. In the present study, we show that mice genetically deficient for Gα(z) are protected from developing glucose intolerance when fed a high fat (45 kcal%) diet. In these mice, a robust increase in β-cell proliferation is correlated with significantly increased β-cell mass. Further, an endogenous Gα(z) signaling pathway, through circulating prostaglandin E activating the EP3 isoform of the E prostanoid receptor, appears to be up-regulated in insulin-resistant, glucose-intolerant mice. These results, along with those of our previous work, link signaling through Gα(z) to both major aspects of β-cell decompensation: insufficient β-cell function and mass.
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Affiliation(s)
- Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705, USA.
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27
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Zhao Y, Fang Q, Straub SG, Lindau M, Sharp GWG. Hormonal inhibition of endocytosis: novel roles for noradrenaline and G protein G(z). J Physiol 2010; 588:3499-509. [PMID: 20643775 DOI: 10.1113/jphysiol.2010.190116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The modulation of endocytosis following exocytosis by noradrenaline (NA), a physiological inhibitor of insulin secretion, was investigated in INS 832/13 cells using patch-clamp capacitance measurements. Endocytosis was inhibited by NA in a pertussis toxin-insensitive manner. Dialysing a synthetic peptide mimicking the C-terminus of the α-subunit of G(z) into the cells blocked the inhibition of endocytosis by NA. Cell-attached capacitance measurements indicated that inhibition by NA was due to a decreased number of endocytotic events without a change in vesicle size. Analysis of fission pore closure kinetics revealed two distinct fission modes, with NA selectively inhibiting the rapid fission pore closure events. Comparison of the actions of NA and deltamethrin, a calcineurin antagonist and potent inhibitor of endocytosis, demonstrated that they inhibit endocytosis by different mechanisms. These findings establish novel actions for NA and G(z) in insulin-secreting cells and possibly other cell types.
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Affiliation(s)
- Ying Zhao
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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Cyclic AMP signaling in pancreatic islets. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:281-304. [PMID: 20217503 DOI: 10.1007/978-90-481-3271-3_13] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cyclic 3'5'AMP (cAMP) is an important physiological amplifier of glucose-induced insulin secretion by the pancreatic islet beta-cell, where it is formed by the activity of adenylyl cyclases, which are stimulated by glucose, through elevation in intracellular calcium concentrations, and by the incretin hormones (GLP-1 and GIP). cAMP is rapidly degraded in the pancreatic islet beta-cell by various cyclic nucleotide phosphodiesterase (PDE) enzymes. Many steps involved in glucose-induced insulin secretion are modulated by cAMP, which is also important in regulating pancreatic islet beta-cell differentiation, growth and survival. This chapter discusses the formation, destruction and actions of cAMP in the islets with particular emphasis on the beta-cell.
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29
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Kelly P, Bailey CL, Fueger PT, Newgard CB, Casey PJ, Kimple ME. Rap1 promotes multiple pancreatic islet cell functions and signals through mammalian target of rapamycin complex 1 to enhance proliferation. J Biol Chem 2010; 285:15777-85. [PMID: 20339002 DOI: 10.1074/jbc.m109.069112] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Recent studies have implicated Epac2, a guanine-nucleotide exchange factor for the Rap subfamily of monomeric G proteins, as an important regulator of insulin secretion from pancreatic beta-cells. Although the Epac proteins were originally identified as cAMP-responsive activators of Rap1 GTPases, the role of Rap1 in beta-cell biology has not yet been defined. In this study, we examined the direct effects of Rap1 signaling on beta-cell biology. Using the Ins-1 rat insulinoma line, we demonstrate that activated Rap1A, but not related monomeric G proteins, promotes ribosomal protein S6 phosphorylation. Using isolated rat islets, we show that this signaling event is rapamycin-sensitive, indicating that it is mediated by the mammalian target of rapamycin complex 1-p70 S6 kinase pathway, a known growth regulatory pathway. This newly defined beta-cell signaling pathway acts downstream of cAMP, in parallel with the stimulation of cAMP-dependent protein kinase, to drive ribosomal protein S6 phosphorylation. Activated Rap1A promotes glucose-stimulated insulin secretion, islet cell hypertrophy, and islet cell proliferation, the latter exclusively through mammalian target of rapamycin complex 1, suggesting that Rap1 is an important regulator of beta-cell function. This newly defined signaling pathway may yield unique targets for the treatment of beta-cell dysfunction in diabetes.
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Affiliation(s)
- Patrick Kelly
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Kimple ME, Joseph JW, Bailey CL, Fueger PT, Hendry IA, Newgard CB, Casey PJ. Galphaz negatively regulates insulin secretion and glucose clearance. J Biol Chem 2007; 283:4560-7. [PMID: 18096703 DOI: 10.1074/jbc.m706481200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Relatively little is known about the in vivo functions of the alpha subunit of the heterotrimeric G protein Gz (Galphaz). Clues to one potential function recently emerged with the finding that activation of Galphaz inhibits glucose-stimulated insulin secretion in an insulinoma cell line (Kimple, M. E., Nixon, A. B., Kelly, P., Bailey, C. L., Young, K. H., Fields, T. A., and Casey, P. J. (2005) J. Biol. Chem. 280, 31708-31713). To extend this study in vivo, a Galphaz knock-out mouse model was utilized to determine whether Galphaz function plays a role in the inhibition of insulin secretion. No differences were discovered in the gross morphology of the pancreatic islets or in the islet DNA, protein, or insulin content between Galphaz-null and wild-type mice. There was also no difference between the insulin sensitivity of Galphaz-null mice and wild-type controls, as measured by insulin tolerance tests. Galphaz-null mice did, however, display increased plasma insulin concentrations and a corresponding increase in glucose clearance following intraperitoneal and oral glucose challenge as compared with wild-type controls. The increased plasma insulin observed in Galphaz-null mice is most likely a direct result of enhanced insulin secretion, since pancreatic islets isolated from Galphaz-null mice exhibited significantly higher glucose-stimulated insulin secretion than those of wild-type mice. Finally, the increased insulin secretion observed in Galphaz-null islets appears to be due to the relief of a tonic inhibition of adenylyl cyclase, as cAMP production was significantly increased in Galphaz-null islets in the absence of exogenous stimulation. These findings indicate that Galphaz may be a potential new target for therapeutics aimed at ameliorating beta-cell dysfunction in Type 2 diabetes.
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Affiliation(s)
- Michelle E Kimple
- Department of Pharmacology, and The Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina 27710-3813, USA
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Nunn C, Mao H, Chidiac P, Albert PR. RGS17/RGSZ2 and the RZ/A family of regulators of G-protein signaling. Semin Cell Dev Biol 2006; 17:390-9. [PMID: 16765607 DOI: 10.1016/j.semcdb.2006.04.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Regulators of G-protein signaling (RGS proteins) comprise over 20 different proteins that have been classified into subfamilies on the basis of structural homology. The RZ/A family includes RGSZ2/RGS17 (the most recently discovered member of this family), GAIP/RGS19, RGSZ1/RGS20, and the RGSZ1 variant Ret-RGS. The RGS proteins are GTPase activating proteins (GAPs) that turn off G-proteins and thus negatively regulate the signaling of G-protein coupled receptors (GPCRs). In addition, some RZ/A family RGS proteins are able to modify signaling through interactions with adapter proteins (such as GIPC and GIPN). The RZ/A proteins have a simple structure that includes a conserved amino-terminal cysteine string motif, RGS box and short carboxyl-terminal, which confer GAP activity (RGS box) and the ability to undergo covalent modification and interact with other proteins (amino-terminal). This review focuses on RGS17 and its RZ/A sibling proteins and discusses the similarities and differences among these proteins in terms of their palmitoylation, phosphorylation, intracellular localization and interactions with GPCRs and adapter proteins. The specificity of these RGS protein for different Galpha proteins and receptors, and the consequences for signaling are discussed. The tissue and brain distribution, and the evolving understanding of the roles of this family of RGS proteins in receptor signaling and brain function are highlighted.
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Affiliation(s)
- Caroline Nunn
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ont., Canada, N6A 5C1
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