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.

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 Impact of Small-Molecule Glucokinase Activator on Glucose Metabolism and β-Cell Mass

Endocrinology ◽  
2008 ◽  
Vol 150 (3) ◽  
pp. 1147-1154 ◽  
Author(s):  
Akinobu Nakamura ◽  
Yasuo Terauchi ◽  
Sumika Ohyama ◽  
Junko Kubota ◽  
Hiroko Shimazaki ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Glucose Metabolism ◽  
Cell Mass ◽  
Isolated Islets ◽  
Brdu Incorporation ◽  
Wild Type ◽  
Β Cell ◽  
Glucokinase Activator ◽  
Insulinoma Cells

We investigated the effect of glucokinase activator (GKA) on glucose metabolism and β-cell mass. We analyzed four mouse groups: wild-type mice and β-cell-specific haploinsufficiency of glucokinase gene (Gck+/−) mice on a high-fat (HF) diet. Each genotype was also treated with GKA mixed in the HF diet. Rodent insulinoma cells and isolated islets were used to evaluate β-cell proliferation by GKA. After 20 wk on the above diets, there were no differences in body weight, lipid profiles, and liver triglyceride content among the four groups. Glucose tolerance was improved shortly after the GKA treatment in both genotypes of mice. β-Cell mass increased in wild-type mice compared with Gck+/− mice, but a further increase was not observed after the administration of GKA in both genotypes. Interestingly, GKA was able to up-regulate insulin receptor substrate-2 (Irs-2) expression in insulinoma cells and isolated islets. The administration of GKA increased 5-bromo-2-deoxyuridine (BrdU) incorporation in insulinoma cells, and 3 d administration of GKA markedly increased BrdU incorporation in mice treated with GKA in both genotypes, compared with those without GKA. In conclusion, GKA was able to chronically improve glucose metabolism for mice on the HF diet. Although chronic GKA administration failed to cause a further increase in β-cell mass in vivo, GKA was able to increase beta cell proliferation in vitro and with a 3-d administration in vivo. This apparent discrepancy can be explained by a chronic reduction in ambient blood glucose levels by GKA treatment. Glucokinase activator is able to improve glucose metabolism and has an effect on β cell proliferation.

scholarly journals The small molecule kobusone can stimulate islet β-cell replication in vivo

2021 ◽  
Vol 49 (7) ◽  
pp. 030006052110328
Author(s):  
Jin woo Choi ◽  
Jin-deok Joo ◽  
Jang hyeok In ◽  
Daewoo Kim ◽  
Yongshin Kim ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Body Weight ◽  
Serum Insulin ◽  
Cyclin D3 ◽  
Control Group ◽  
Cell Replication ◽  
Β Cell ◽  
Insulin Levels ◽  
Glucose Levels

Objective To investigate the ability of kobusone to reduce high glucose levels and promote β-cell proliferation. Methods Four-week-old female db/db mice were assigned to the kobusone (25 mg/kg body weight, intraperitoneally twice a day) or control group (same volume of PBS). Glucose levels and body weight were measured twice a week. After 6 weeks, intraperitoneal glucose tolerance tests and immunohistochemical studies were performed, and insulin levels were determined. The expression of mRNAs involved in cell proliferation, such as PI3K, Akt, cyclin D3 and p57Kip 2 , was measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Results Kobusone reduced blood glucose levels after 3 weeks and more strongly increased serum insulin levels than the vehicle. Immunohistochemistry illustrated that kobusone increased 5-bromo-2′-deoxyuridine incorporation into islet β-cells, suggesting that it can stimulate islet β-cell replication in vivo. RT-qPCR indicated that kobusone upregulated the mRNA expression of PI3K, Akt, and cyclin D3 and downregulated that of p57Kip2. Conclusion Our findings suggest that kobusone is a potent pancreatic islet β-cell inducer that has the potential to be developed as an anti-diabetic agent.

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 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.

Quantification of the relationship between glycemia and β-cell mass adaptation in vivo

2009 ◽  
Vol 87 (8) ◽  
pp. 602-609 ◽  
Author(s):  
Laura L. Atkinson ◽  
Brian G. Topp ◽  
Jenny Au ◽  
Horatiu V. Vinerian ◽  
Narinder Dhatt ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Cell Mass ◽  
Cell Replication ◽  
Sprague Dawley ◽  
Β Cell ◽  
Insulin Levels ◽  
Hyperglycemic Clamp ◽  
Sprague Dawley Rats ◽  
Significant Difference

β-cell mass dynamics play an important role in the adaptation to obesity, as well as in the pathogenesis of type 2 diabetes. Here we used a 24-hour modified hyperglycemic clamp protocol to investigate the effect of increasing glucose concentrations (15, 20, 25, or 35 mmol/L) on β-cell mass and rates of β-cell replication, death, and neogenesis in 6-week-old Sprague Dawley rats (n = 40). During the first 4 h of glucose infusion, plasma insulin levels rose to an approximate steady state in each group, but by the end of 24 h, there was no difference in insulin levels between any of the groups. There was also no difference in β-cell mass between groups. Mean β-cell replication rates displayed a linear relationship to mean plasma glucose levels in all hyperglycemic animals (r2 = 0.98, p < 0.05). Relative to the uninfused basal control animals, replication rates were significantly reduced in the 15 mmol/L glucose group. The percentage of TUNEL-positive β-cells was not different between groups. There was also no significant difference in markers of neogenesis. Thus, these data demonstrate that hyperglycemia for 24 h had no effect on β-cell mass, death, or neogenesis in 6-week-old Sprague Dawley rats. We demonstrate a linear relationship, however, between hyperglycemia and β-cell replication rates in vivo.

scholarly journals PFKFB3 DEPLETION ACTIVATES β–CELL REPLICATION BY CELL COMPETITIVE CULLING OF COMPROMISED β–CELLS UNDER STRESS

2021 ◽  
Author(s):  
Jie Min ◽  
Feyiang Ma ◽  
Matteo Pellegrini ◽  
Oppel Greeff ◽  
Salvador Moncada ◽  
...  
Keyword(s):  
Glucose Intolerance ◽  
Critical Role ◽  
Cell Mass ◽  
Cell Replication ◽  
Β Cells ◽  
Β Cell ◽  
Cell Competition ◽  
Islet Amyloid ◽  
And Function

Highly conserved hypoxia–inducible factor 1 alpha (HIF1α) and its target 6–phosphofructo–2–kinase/fructose–2,6–biphosphatase 3 (PFKFB3) play a critical role in the survival of damaged β–cells in type 2 diabetes (T2D) while rendering β–cells non–responsive to glucose stimulation by mitochondrial suppression. HIF1α –PFKFB3 is activated in 30–50% of all β–cells in diabetic islets, leaving an open question of whether targeting this pathway may adjust β–cell mass and function to the specific metabolic demands during diabetogenic stress. Our previous studies of β–cells under amyloidogenic stress by human islet amyloid polypeptide (hIAPP) revealed that PFKFB3 is a metabolic execution arm of the HIF1α pathway with potent implications on Ca2+ homeostasis, metabolome, and mitochondrial form and function. To discriminate the role of PFKFB3 from HIF1α in vivo, we generated mice with conditional β–cell specific disruption of the Pfkfb3 gene on a heterozygous hIAPP background and a high–fat diet (HFD) [PFKFB3βKO + diabetogenic stress (DS)]. PFKFB3 disruption in β–cells under diabetogenic stress led to selective purging of hIAPP–damaged β–cells and the disappearance of bihormonal insulin– and glucagon–positive cells, thus compromised β–cells. At the same time, PFKFB3 disruption led to a three–fold increase in β–cell replication resembling control levels as measured with minichromosome maintenance 2 protein (MCM2). PFKFB3 disruption depleted bihormonal cells while increased β–cell replication that was reflected in the increased β–/α–cell ratio and maintained β–cell mass. Analysis of metabolic performance indicated comparable glucose intolerance and reduced plasma insulin levels in PFKFB3βKO DS relative to PFKFB3WT DS mice. In the PFKFB3βKO DS group, plasma glucagon levels were reduced compared to PFKFB3WT DS mice and were in line with increased insulin sensitivity. Glucose intolerance in PFKFB3βKO DS mice could be explained by the compensatory expression of HIF1α after disruption of PFKFB3. Our data strongly suggest that the replication and functional recovery of β–cells under diabetogenic stress depend on selective purification of HIF1α and PFKFB3–positive β–cells. Thus, HIF1α–PFKFB3–dependent activation of cell competition and purging of compromised β–cells may yield functional competent β–cell mass in diabetes.

scholarly journals ACE2 deficiency reduces β-cell mass and impairs β-cell proliferation in obese C57BL/6 mice

2015 ◽  
Vol 309 (7) ◽  
pp. E621-E631 ◽  
Author(s):  
Robin Shoemaker ◽  
Frederique Yiannikouris ◽  
Sean Thatcher ◽  
Lisa Cassis
Keyword(s):  
Cell Proliferation ◽  
Cell Function ◽  
Critical Role ◽  
Cell Mass ◽  
Renin Angiotensin System ◽  
Β Cell ◽  
Β Cell Function ◽  
Islet Dysfunction ◽  
Glucose Stimulated Insulin Secretion

Drugs that inhibit the renin-angiotensin system (RAS) decrease the onset of type 2 diabetes (T2D). Pancreatic islets express RAS components, including angiotensin-converting enzyme 2 (ACE2), which cleaves angiotensin II (Ang II) to angiotensin-(1–7) [Ang-(1–7)]. Overexpression of ACE2 in pancreas of diabetic mice improved glucose homeostasis. The purpose of this study was to determine if deficiency of endogenous ACE2 contributes to islet dysfunction and T2D. We hypothesized that ACE2 deficiency potentiates the decline in β-cell function and augments the development of diet-induced T2D. Male Ace2 +/y or Ace2 −/y mice were fed a low-fat (LF) or high-fat (HF) diet for 1 or 4 mo. A subset of 1-mo HF-fed mice were infused with Sal (Sal), losartan (Los), or Ang-(1–7). At 4 mo, while both genotypes of HF-fed mice developed a similar level of insulin resistance, adaptive hyperinsulinemia was reduced in Ace2 −/y vs. Ace2 +/y mice. Similarly, in vivo glucose-stimulated insulin secretion (GSIS) was reduced in 1-mo HF-fed Ace2 −/y compared with Ace2 +/y mice, resulting in augmented hyperglycemia. The average islet area was significantly smaller in both LF- and HF-fed Ace2 −/y vs. Ace2 +/y mice. Additionally, β-cell mass and proliferation were reduced significantly in HF-fed Ace2 −/y vs. Ace2 +/y mice. Neither infusion of Los nor Ang-(1–7) was able to correct impaired in vivo GSIS of HF-fed ACE2-deficient mice. These results demonstrate a critical role for endogenous ACE2 in the adaptive β-cell hyperinsulinemic response to HF feeding through regulation of β-cell proliferation and growth.

scholarly journals First quantitative high-throughput screen in zebrafish identifies novel pathways for increasing pancreatic β-cell mass

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Guangliang Wang ◽  
Surendra K Rajpurohit ◽  
Fabien Delaspre ◽  
Steven L Walker ◽  
David T White ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Drug Discovery ◽  
High Throughput ◽  
Cell Mass ◽  
In Vitro Assays ◽  
Β Cell ◽  
Federal Drug Administration ◽  
Chemical Screening ◽  
Endocrine Differentiation

Whole-organism chemical screening can circumvent bottlenecks that impede drug discovery. However, in vivo screens have not attained throughput capacities possible with in vitro assays. We therefore developed a method enabling in vivo high-throughput screening (HTS) in zebrafish, termed automated reporter quantification in vivo (ARQiv). In this study, ARQiv was combined with robotics to fully actualize whole-organism HTS (ARQiv-HTS). In a primary screen, this platform quantified cell-specific fluorescent reporters in >500,000 transgenic zebrafish larvae to identify FDA-approved (Federal Drug Administration) drugs that increased the number of insulin-producing β cells in the pancreas. 24 drugs were confirmed as inducers of endocrine differentiation and/or stimulators of β-cell proliferation. Further, we discovered novel roles for NF-κB signaling in regulating endocrine differentiation and for serotonergic signaling in selectively stimulating β-cell proliferation. These studies demonstrate the power of ARQiv-HTS for drug discovery and provide unique insights into signaling pathways controlling β-cell mass, potential therapeutic targets for treating diabetes.

scholarly journals Prolactin Receptor Is Required for Normal Glucose Homeostasis and Modulation of β-Cell Mass during Pregnancy

Endocrinology ◽  
2008 ◽  
Vol 150 (4) ◽  
pp. 1618-1626 ◽  
Author(s):  
Carol Huang ◽  
Frances Snider ◽  
James C. Cross
Keyword(s):  
Cell Proliferation ◽  
Glucose Tolerance ◽  
Glucose Homeostasis ◽  
Prolactin Receptor ◽  
Cell Mass ◽  
Β Cell ◽  
Related Factors ◽  
Maternal Glucose

Increased islet mass is an adaptive mechanism that occurs to combat insulin resistance during pregnancy. Prolactin (PRL) can enhance β-cell proliferation and insulin secretion in vitro, yet whether it is PRL or other pregnancy-related factors that mediate these adaptive changes during pregnancy is unknown. The objective of this study was to determine whether prolactin receptor (Prlr) is required for normal maternal glucose homeostasis during pregnancy. An ip glucose tolerance test was performed on timed-pregnant Prlr+/+ and heterozygous null Prlr+/− mice on d 0, 15, and 18 of pregnancy. Compared with Prlr+/+ mice, Prlr+/− mice had impaired glucose clearance, decreased glucose-stimulated insulin release, higher nonfasted blood glucose, and lower insulin levels during but not before pregnancy. There was no difference in their insulin tolerance. Prlr+/+ mice show a significant incremental increase in islet density and β-cell number and mass throughout pregnancy, which was attenuated in the Prlr+/− mice. Prlr+/+ mice also had a more robust β-cell proliferation rate during pregnancy, whereas there was no difference in apoptosis rate between the Prlr+/+ and Prlr+/− mice before, during, or after pregnancy. Interestingly, genotype of the mothers had a significant impact on the offspring’s phenotype, such that daughters derived from Prlr+/− mothers had a more severe phenotype than those derived from Prlr+/+ mothers. In conclusion, this is the first in vivo demonstration that the action of pregnancy hormones, acting through Prlr, is required for normal maternal glucose tolerance during pregnancy by increasing β-cell mass.

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