scholarly journals Role of the G-Protein Coupled Receptor 3-Salt Inducible Kinase 2 Pathway in Human β Cell Proliferation

2021 ◽  
Author(s):  
Caterina Iorio ◽  
Jillian L Rourke ◽  
Lisa Wells ◽  
Jun-Ichi Sakamaki ◽  
Emily Moon ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
G Protein ◽  
Cell Mass ◽  
Standard Of Care ◽  
G Protein Coupled Receptor ◽  
Β Cells ◽  
Β Cell ◽  
Cell Therapies ◽  
G Protein Coupled

Loss of pancreatic β cells is the hallmark of type 1 diabetes (T1D), for which provision of insulin is the standard of care. While regenerative and stem cell therapies hold the promise of generating single-source or host-matched tissue to obviate immune-mediated complications, these will still require surgical intervention and immunosuppression. Thus, methods that harness the innate capacity of β cells to proliferate to increase β cell mass in vivo are considered vital for future T1D treatment. However, early in life β cells enter what appears to be a permanent state of quiescence, directed by an evolutionarily selected genetic program that establishes a β cell mass setpoint to guard against development of fatal endocrine tumours. Here we report the development of a high-throughput RNAi screening approach to identify upstream pathways that regulate adult human β cell quiescence and demonstrate in a screen of the GPCRome that silencing G-protein coupled receptor 3 (GPR3) leads to human pancreatic β cell proliferation. Loss of GPR3 leads to activation of Salt Inducible Kinase 2 (SIK2), which is necessary and sufficient to drive cell cycle entry, increase β cell mass, and enhance insulin secretion in mice. Taken together, targeting the GPR3-SIK2 pathway represents a novel avenue to stimulate the regeneration of β cells.

scholarly journals Silencing the G-protein coupled receptor 3-salt inducible kinase 2 pathway promotes human β cell proliferation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Caterina Iorio ◽  
Jillian L. Rourke ◽  
Lisa Wells ◽  
Jun-Ichi Sakamaki ◽  
Emily Moon ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
G Protein ◽  
Cell Mass ◽  
Standard Of Care ◽  
G Protein Coupled Receptor ◽  
Β Cells ◽  
Β Cell ◽  
Cell Therapies ◽  
Potential Strategy ◽  
G Protein Coupled

AbstractLoss of pancreatic β cells is the hallmark of type 1 diabetes, for which provision of insulin is the standard of care. While regenerative and stem cell therapies hold the promise of generating single-source or host-matched tissue to obviate immune-mediated complications, these will still require surgical intervention and immunosuppression. Here we report the development of a high-throughput RNAi screening approach to identify upstream pathways that regulate adult human β cell quiescence and demonstrate in a screen of the GPCRome that silencing G-protein coupled receptor 3 (GPR3) leads to human pancreatic β cell proliferation. Loss of GPR3 leads to activation of Salt Inducible Kinase 2 (SIK2), which is necessary and sufficient to drive cell cycle entry, increase β cell mass, and enhance insulin secretion in mice. Taken together, our data show that targeting the GPR3-SIK2 pathway is a potential strategy to stimulate the regeneration of β cells.

scholarly journals Evidence for Osteocalcin Binding and Activation of GPRC6A in β-Cells

Endocrinology ◽  
2016 ◽  
Vol 157 (5) ◽  
pp. 1866-1880 ◽  
Author(s):  
Min Pi ◽  
Karan Kapoor ◽  
Ruisong Ye ◽  
Satoru Kenneth Nishimoto ◽  
Jeremy C. Smith ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
G Protein ◽  
Computational Models ◽  
Transmembrane Domain ◽  
Structural Basis ◽  
G Protein Coupled Receptor ◽  
Β Cells ◽  
Β Cell ◽  
Cell Functions ◽  
G Protein Coupled

Abstract The possibility that G protein-coupled receptor family C member A (GPRC6A) is the osteocalcin (Ocn)-sensing G protein-coupled receptor that directly regulates pancreatic β-cell functions is controversial. In the current study, we found that Ocn and an Ocn-derived C-terminal hexapeptide directly activate GPRC6A-dependent ERK signaling in vitro. Computational models probe the structural basis of Ocn binding to GPRC6A and predict that the C-terminal hexapeptide docks to the extracellular side of the transmembrane domain of GPRC6A. Consistent with the modeling, mutations in the computationally identified binding pocket of GPRC6A reduced Ocn and C-terminal hexapeptide activation of this receptor. In addition, selective deletion of Gprc6a in β-cells (Gprc6aβ-cell-cko) by crossing Gprc6aflox/flox mice with Ins2-Cre mice resulted in reduced pancreatic weight, islet number, insulin protein content, and insulin message expression. Both islet size and β-cell proliferation were reduced in Gprc6aβ-cell-cko compared with control mice. Gprc6aβ-cell-cko exhibited abnormal glucose tolerance, but normal insulin sensitivity. Islets isolated from Gprc6aβ-cell-cko mice showed reduced insulin simulation index in response to Ocn. These data establish the structural basis for Ocn direct activation of GPRC6A and confirm a role for GPRC6A in regulating β-cell proliferation and insulin secretion.

scholarly journals NF-κB activity during pancreas development regulates adult β-cell mass by modulating neonatal β-cell proliferation and apoptosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dror Sever ◽  
Anat Hershko-Moshe ◽  
Rohit Srivastava ◽  
Roy Eldor ◽  
Daniel Hibsher ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Developmental Stages ◽  
Cell Mass ◽  
Diabetes Incidence ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Regulatory Circuit ◽  
Proliferation And Apoptosis

AbstractNF-κB is a well-characterized transcription factor, widely known for its roles in inflammation and immune responses, as well as in control of cell division and apoptosis. However, its function in β-cells is still being debated, as it appears to depend on the timing and kinetics of its activation. To elucidate the temporal role of NF-κB in vivo, we have generated two transgenic mouse models, the ToIβ and NOD/ToIβ mice, in which NF-κB activation is specifically and conditionally inhibited in β-cells. In this study, we present a novel function of the canonical NF-κB pathway during murine islet β-cell development. Interestingly, inhibiting the NF-κB pathway in β-cells during embryogenesis, but not after birth, in both ToIβ and NOD/ToIβ mice, increased β-cell turnover, ultimately resulting in a reduced β-cell mass. On the NOD background, this was associated with a marked increase in insulitis and diabetes incidence. While a robust nuclear immunoreactivity of the NF-κB p65-subunit was found in neonatal β-cells, significant activation was not detected in β-cells of either adult NOD/ToIβ mice or in the pancreata of recently diagnosed adult T1D patients. Moreover, in NOD/ToIβ mice, inhibiting NF-κB post-weaning had no effect on the development of diabetes or β-cell dysfunction. In conclusion, our data point to NF-κB as an important component of the physiological regulatory circuit that controls the balance of β-cell proliferation and apoptosis in the early developmental stages of insulin-producing cells, thus modulating β-cell mass and the development of diabetes in the mouse model of T1D.

scholarly journals Loss of Foxd3 Results in Decreased β-Cell Proliferation and Glucose Intolerance During Pregnancy

Endocrinology ◽  
2011 ◽  
Vol 152 (12) ◽  
pp. 4589-4600 ◽  
Author(s):  
Jennifer L. Plank ◽  
Audrey Y. Frist ◽  
Alison W. LeGrone ◽  
Mark A. Magnuson ◽  
Patricia A. Labosky
Keyword(s):  
Cell Proliferation ◽  
Cell Mass ◽  
Diabetic Patients ◽  
Β Cells ◽  
Β Cell ◽  
Forkhead Box ◽  
Physiological Demands ◽  
Mass Expansion ◽  
Specific Deletion

A complete molecular understanding of β-cell mass expansion will be useful for the improvement of therapies to treat diabetic patients. During normal periods of metabolic challenges, such as pregnancy, β-cells proliferate, or self-renew, to meet the new physiological demands. The transcription factor Forkhead box D3 (Foxd3) is required for maintenance and self-renewal of several diverse progenitor cell lineages, and Foxd3 is expressed in the pancreatic primordium beginning at 10.5 d postcoitum, becoming localized predominantly to β-cells after birth. Here, we show that mice carrying a pancreas-specific deletion of Foxd3 have impaired glucose tolerance, decreased β-cell mass, decreased β-cell proliferation, and decreased β-cell size during pregnancy. In addition, several genes known to regulate proliferation, Foxm1, Skp2, Ezh2, Akt2, and Cdkn1a, are misregulated in islets isolated from these Foxd3 mutant mice. Together, these data place Foxd3 upstream of several pathways critical for β-cell mass expansion in vivo.

scholarly journals GRK2 regulates GLP-1R-mediated early phase insulin secretion in vivo

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Alba C. Arcones ◽  
Rocío Vila-Bedmar ◽  
Mercedes Mirasierra ◽  
Marta Cruces-Sande ◽  
Mario Vallejo ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
G Protein ◽  
Insulin Release ◽  
Cell Lines ◽  
Early Phase ◽  
G Protein Coupled Receptor ◽  
Β Cell ◽  
Insulin Secretion In Vivo ◽  
G Protein Coupled

Abstract Background Insulin secretion from the pancreatic β-cell is finely modulated by different signals to allow an adequate control of glucose homeostasis. Incretin hormones such as glucagon-like peptide-1 (GLP-1) act as key physiological potentiators of insulin release through binding to the G protein-coupled receptor GLP-1R. Another key regulator of insulin signaling is the Ser/Thr kinase G protein-coupled receptor kinase 2 (GRK2). However, whether GRK2 affects insulin secretion or if GRK2 can control incretin actions in vivo remains to be analyzed. Results Using GRK2 hemizygous mice, isolated pancreatic islets, and model β-cell lines, we have uncovered a relevant physiological role for GRK2 as a regulator of incretin-mediated insulin secretion in vivo. Feeding, oral glucose gavage, or administration of GLP-1R agonists in animals with reduced GRK2 levels (GRK2+/− mice) resulted in enhanced early phase insulin release without affecting late phase secretion. In contrast, intraperitoneal glucose-induced insulin release was not affected. This effect was recapitulated in isolated islets and correlated with the increased size or priming efficacy of the readily releasable pool (RRP) of insulin granules that was observed in GRK2+/− mice. Using nanoBRET in β-cell lines, we found that stimulation of GLP-1R promoted GRK2 association to this receptor and that GRK2 protein and kinase activity were required for subsequent β-arrestin recruitment. Conclusions Overall, our data suggest that GRK2 is an important negative modulator of GLP-1R-mediated insulin secretion and that GRK2-interfering strategies may favor β-cell insulin secretion specifically during the early phase, an effect that may carry interesting therapeutic applications.

Islet-selectivity of G-protein coupled receptor ligands evaluated for PET imaging of pancreatic β-cell mass

2011 ◽  
Vol 412 (3) ◽  
pp. 413-418 ◽  
Author(s):  
Gary W. Cline ◽  
Xiaojian Zhao ◽  
Amy B. Jakowski ◽  
Walter C. Soeller ◽  
Judith L. Treadway
Keyword(s):  
G Protein ◽  
Pet Imaging ◽  
Cell Mass ◽  
Pancreatic Β Cell ◽  
Receptor Ligands ◽  
G Protein Coupled Receptor ◽  
Β Cell ◽  
G Protein Coupled

scholarly journals Ontology of the apelinergic system in mouse pancreas during pregnancy and relationship with β-cell mass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brenda Strutt ◽  
Sandra Szlapinski ◽  
Thineesha Gnaneswaran ◽  
Sarah Donegan ◽  
Jessica Hill ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Insulin Secretion ◽  
Glucose Transporter ◽  
Cell Mass ◽  
Elevated Serum ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Glucose Transporter 2 ◽  
Glucose Stimulated Insulin Secretion

AbstractThe apelin receptor (Aplnr) and its ligands, Apelin and Apela, contribute to metabolic control. The insulin resistance associated with pregnancy is accommodated by an expansion of pancreatic β-cell mass (BCM) and increased insulin secretion, involving the proliferation of insulin-expressing, glucose transporter 2-low (Ins+Glut2LO) progenitor cells. We examined changes in the apelinergic system during normal mouse pregnancy and in pregnancies complicated by glucose intolerance with reduced BCM. Expression of Aplnr, Apelin and Apela was quantified in Ins+Glut2LO cells isolated from mouse pancreata and found to be significantly higher than in mature β-cells by DNA microarray and qPCR. Apelin was localized to most β-cells by immunohistochemistry although Aplnr was predominantly associated with Ins+Glut2LO cells. Aplnr-staining cells increased three- to four-fold during pregnancy being maximal at gestational days (GD) 9–12 but were significantly reduced in glucose intolerant mice. Apelin-13 increased β-cell proliferation in isolated mouse islets and INS1E cells, but not glucose-stimulated insulin secretion. Glucose intolerant pregnant mice had significantly elevated serum Apelin levels at GD 9 associated with an increased presence of placental IL-6. Placental expression of the apelinergic axis remained unaltered, however. Results show that the apelinergic system is highly expressed in pancreatic β-cell progenitors and may contribute to β-cell proliferation in pregnancy.

scholarly journals Insulin Stimulates Primary β-Cell Proliferation via Raf-1 Kinase

Endocrinology ◽  
2008 ◽  
Vol 149 (5) ◽  
pp. 2251-2260 ◽  
Author(s):  
Jennifer L. Beith ◽  
Emilyn U. Alejandro ◽  
James D. Johnson
Keyword(s):  
Cell Proliferation ◽  
Dominant Role ◽  
Cell Mass ◽  
Diabetes Type 2 ◽  
Dominant Negative ◽  
Cell Replication ◽  
Β Cell ◽  
Physiological Control ◽  
Primary Mouse

A relative decrease in β-cell mass is key in the pathogenesis of type 1 diabetes, type 2 diabetes, and in the failure of transplanted islet grafts. It is now clear that β-cell duplication plays a dominant role in the regulation of adult β-cell mass. Therefore, knowledge of the endogenous regulators of β-cell replication is critical for understanding the physiological control of β-cell mass and for harnessing this process therapeutically. We have shown that concentrations of insulin known to exist in vivo act directly on β-cells to promote survival. Whether insulin stimulates adult β-cell proliferation remains unclear. We tested this hypothesis using dispersed primary mouse islet cells double labeled with 5-bromo-2-deoxyuridine and insulin antisera. Treating cells with 200-pm insulin significantly increased proliferation from a baseline rate of 0.15% per day. Elevating glucose from 5–15 mm did not significantly increase β-cell replication. β-Cell proliferation was inhibited by somatostatin as well as inhibitors of insulin signaling. Interestingly, inhibiting Raf-1 kinase blocked proliferation stimulated by low, but not high (superphysiological), insulin doses. Insulin-stimulated mouse insulinoma cell proliferation was dependent on both phosphatidylinositol 3-kinase/Akt and Raf-1/MAPK kinase pathways. Overexpression of Raf-1 was sufficient to increase proliferation in the absence of insulin, whereas a dominant-negative Raf-1 reduced proliferation in the presence of 200-pm insulin. Together, these results demonstrate for the first time that insulin, at levels that have been measured in vivo, can directly stimulate β-cell proliferation and that Raf-1 kinase is involved in this process. These findings have significant implications for the understanding of the regulation of β-cell mass in both the hyperinsulinemic and insulin-deficient states that occur in the various forms of diabetes.

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