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

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.

Download Full-text

Regulation of glucokinase in pancreatic islets by prolactin: a mechanism for increasing glucose-stimulated insulin secretion during pregnancy

Journal of Endocrinology ◽

10.1677/joe-07-0043 ◽

2007 ◽

Vol 193 (3) ◽

pp. 367-381 ◽

Cited By ~ 55

Author(s):

Anthony J Weinhaus ◽

Laurence E Stout ◽

Nicholas V Bhagroo ◽

T Clark Brelje ◽

Robert L Sorenson

Keyword(s):

Insulin Secretion ◽

Glucose Metabolism ◽

Pancreatic Islets ◽

Glucose Transporter ◽

Β Cells ◽

Glucose Transporter 2 ◽

Underlying Mechanisms ◽

Glucose Stimulated Insulin Secretion ◽

Induced Changes

Glucokinase activity is increased in pancreatic islets during pregnancy and in vitro by prolactin (PRL). The underlying mechanisms that lead to increased glucokinase have not been resolved. Since glucose itself regulates glucokinase activity in β-cells, it was unclear whether the lactogen effects are direct or occur through changes in glucose metabolism. To clarify the roles of glucose metabolism in this process, we examined the interactions between glucose and PRL on glucose metabolism, insulin secretion, and glucokinase expression in insulin 1 (INS-1) cells and rat islets. Although the PRL-induced changes were more pronounced after culture at higher glucose concentrations, an increase in glucose metabolism, insulin secretion, and glucokinase expression occurred even in the absence of glucose. The presence of comparable levels of insulin secretion at similar rates of glucose metabolism from both control and PRL-treated INS-1 cells suggests the PRL-induced increase in glucose metabolism is responsible for the increase in insulin secretion. Similarly, increases in other known PRL responsive genes (e.g. the PRL receptor, glucose transporter-2, and insulin) were also detected after culture without glucose. We show that the upstream glucokinase promoter contains multiple STAT5 binding sequences with increased binding in response to PRL. Corresponding increases in glucokinase mRNA and protein synthesis were also detected. This suggests the PRL-induced increase in glucokinase mRNA and its translation are sufficient to account for the elevated glucokinase activity in β-cells with lactogens. Importantly, the increase in islet glucokinase observed with PRL is in line with that observed in islets during pregnancy.

Download Full-text

Inhibition of Forkhead Box O1 Protects Pancreatic β-Cells against Dexamethasone-Induced Dysfunction

Endocrinology ◽

10.1210/en.2009-0343 ◽

2009 ◽

Vol 150 (9) ◽

pp. 4065-4073 ◽

Cited By ~ 24

Author(s):

Xiongfei Zhang ◽

Wei Yong ◽

Jinghuan Lv ◽

Yunxia Zhu ◽

Jingjing Zhang ◽

...

Keyword(s):

Insulin Secretion ◽

Cell Types ◽

Pancreatic Β Cell ◽

Rinm5f Cells ◽

Β Cells ◽

Β Cell ◽

Rat Islets ◽

Cell Dysfunction ◽

Forkhead Box ◽

Glucose Stimulated Insulin Secretion

Abstract Forkhead Box O1 (FoxO1) is a key transcription regulator of insulin/IGF-I signaling pathway, and its activity can be increased by dexamethasone (DEX) in several cell types. However, the role of FoxO1 in DEX-induced pancreatic β-cell dysfunction has not been fully understood. Therefore, in this study, we investigated whether FoxO1 could mediate DEX-induced β-cell dysfunction and the possible underlying mechanisms in pancreatic β-cell line RINm5F cells and primary rat islet. We found that DEX markedly increased FoxO1 mRNA and protein expression and decreased FoxO1 phosphorylation through the Akt pathway, which resulted in an increase in active FoxO1 in RINm5F cells and isolated rat islets. Activated FoxO1 subsequently inhibited pancreatic duodenal homeobox-1 expression and induced nuclear exclusion of pancreatic duodenal homeobox-1. Knockdown of FoxO1 by RNA interference restored the expression of pancreatic duodenal homeobox-1 and prevented DEX-induced dysfunction of glucose-stimulated insulin secretion in rat islets. Together, the results of present study demonstrate that FoxO1 is integrally involved in DEX-induced inhibition of pancreatic duodenal homeobox-1 and glucose-stimulated insulin secretion dysfunction in pancreatic islet β-cells. Inhibition of FoxO1 can effectively protect β-cells against DEX-induced dysfunction.

Download Full-text

Maternal Low Protein Isocaloric Diet Suppresses Pancreatic β-Cell Proliferation in Mouse Offspring via miR-15b

Endocrinology ◽

10.1210/en.2016-1167 ◽

2016 ◽

Vol 157 (12) ◽

pp. 4782-4793 ◽

Cited By ~ 12

Author(s):

Yutong Su ◽

Xiuli Jiang ◽

Yanli Li ◽

Feng Li ◽

Yulong Cheng ◽

...

Keyword(s):

Cell Proliferation ◽

Insulin Secretion ◽

Islet Cells ◽

Control Diet ◽

Cell Mass ◽

Pancreatic Β Cell ◽

Β Cell ◽

Isocaloric Diet ◽

Low Protein ◽

And Control

The mechanism underlying the increased susceptibility of type 2 diabetes in offspring of maternal malnutrition is poorly determined. Here we tested the hypothesis that functional microRNAs (miRNAs) mediated the maternal low-protein (LP) isocaloric diet induced pancreatic β-cell impairment. We performed miRNA profiling in the islets from offspring of LP and control diet mothers to explore the potential functional miRNAs responsible for β-cell dysfunction. We found that LP offspring exhibited impaired glucose tolerance due to decreased β-cell mass and insulin secretion. Reduction in the β-cell proliferation rate and cell size contributed to the decreased β-cell mass. MiR-15b was up-regulated in the islets of LP offspring. The up-regulated miR-15b inhibited pancreatic β-cell proliferation via targeting cyclin D1 and cyclin D2. Inhibition of miR-15b in LP islet cells restored β-cell proliferation and insulin secretion. Our findings demonstrate that miR-15b is critical for the regulation of pancreatic β-cells in offspring of maternal protein restriction, which may provide a further insight for β-cell exhaustion originated from intrauterine growth restriction.

Download Full-text

The Plasticity of Pancreatic β-Cells

Metabolites ◽

10.3390/metabo11040218 ◽

2021 ◽

Vol 11 (4) ◽

pp. 218

Author(s):

Norikiyo Honzawa ◽

Kei Fujimoto

Keyword(s):

Insulin Secretion ◽

Progenitor Cells ◽

Islet Cells ◽

Cell Mass ◽

Pancreatic Β Cell ◽

Cell Plasticity ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Impaired Insulin

Type 2 diabetes is caused by impaired insulin secretion and/or insulin resistance. Loss of pancreatic β-cell mass detected in human diabetic patients has been considered to be a major cause of impaired insulin secretion. Additionally, apoptosis is found in pancreatic β-cells; β-cell mass loss is induced when cell death exceeds proliferation. Recently, however, β-cell dedifferentiation to pancreatic endocrine progenitor cells and β-cell transdifferentiation to α-cell was reported in human islets, which led to a new underlying molecular mechanism. Hyperglycemia inhibits nuclear translocation and expression of forkhead box-O1 (FoxO1) and induces the expression of neurogenin-3(Ngn3), which is required for the development and maintenance of pancreatic endocrine progenitor cells. This new hypothesis (Foxology) is attracting attention because it explains molecular mechanism(s) underlying β-cell plasticity. The lineage tracing technique revealed that the contribution of dedifferentiation is higher than that of β-cell apoptosis retaining to β-cell mass loss. In addition, islet cells transdifferentiate each other, such as transdifferentiation of pancreatic β-cell to α-cell and vice versa. Islet cells can exhibit plasticity, and they may have the ability to redifferentiate into any cell type. This review describes recent findings in the dedifferentiation and transdifferentiation of β-cells. We outline novel treatment(s) for diabetes targeting islet cell plasticity.

Download Full-text

Nuclear Factor Y in Male Mouse pancreatic β-cells Plays a Crucial Role in Glucose Homeostasis by Regulating β-Cell Mass and Insulin Secretion

10.2337/figshare.14547255 ◽

2021 ◽

Author(s):

Yin Liu ◽

Siyuan He ◽

Ruixue Zhou ◽

Xueping Zhang ◽

Shanshan Yang ◽

...

Keyword(s):

Cell Proliferation ◽

Insulin Secretion ◽

Cell Mass ◽

Physiological Role ◽

Nuclear Factor ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Nuclear Factor Y

Pancreatic β-cell mass and insulin secretion are determined by the dynamic change of transcription factor expression levels in response to altered metabolic demand. Nuclear factor-Y (NF-Y) is an evolutionarily conserved transcription factor playing critical roles in multiple cellular processes. However, the physiological role of NF-Y in pancreatic β-cells is poorly understood. The present study was undertaken in a conditional knockout of Nf-ya specifically in pancreatic β-cells (Nf-ya βKO) to define the essential physiological role of NF-Y in β-cells. Nf-ya βKO mice exhibited glucose intolerance without changes in insulin sensitivity. Reduced β-cell proliferation resulting in decreased β-cell mass was observed in these mice, which was associated with disturbed actin cytoskeleton. NF-Y-deficient β-cells also exhibited impaired insulin secretion with a reduced Ca2+ influx in response to glucose, which was associated an inefficient glucose uptake into β-cells due to a decreased expression of glucose transporter 2 and a reduction in ATP production resulting from the disruption of mitochondrial integrity. This study is the first to show that NF-Y is critical for pancreatic islets homeostasis and function through regulation in β-cell proliferation, glucose uptake into β-cells, and mitochondrial energy metabolism. Modulating NF-Y expression in β-cells may therefore offer an attractive approach for therapeutic intervention.

Download Full-text

Puerarin protects pancreatic β-cell survival via PI3K/Akt signaling pathway

Journal of Molecular Endocrinology ◽

10.1530/jme-13-0302 ◽

2014 ◽

Vol 53 (1) ◽

pp. 71-79 ◽

Cited By ~ 36

Author(s):

Zhipeng Li ◽

Zhaoshui Shangguan ◽

Yijie Liu ◽

Jihua Wang ◽

Xuejun Li ◽

...

Keyword(s):

Cell Survival ◽

Cell Mass ◽

Akt Signaling ◽

Pancreatic Β Cell ◽

Diabetic Mice ◽

Akt Signaling Pathway ◽

Β Cells ◽

Β Cell ◽

Glucose Stimulated Insulin Secretion ◽

And Function

Pancreatic β-cell loss because of apoptosis is the major cause of type 1 diabetes (T1D) and late stage T2D. Puerarin possesses anti-diabetic properties; whether it acts directly on pancreatic β-cell is not clear. This study was designed to investigate the effects of puerarin on pancreatic β-cell survival and function. Diabetes was induced in male C57BL/6 mice by a single peritoneal injection of streptozotocin (STZ). Pancreatic β-cell survival and function were assessed in diabetic mice by measuring β-cell apoptosis, β-cell mass, pancreatic insulin content, and glucose tolerance, and in cultured islets and clonial MIN6 β-cells by measuring β-cell viability and apoptosis and glucose-stimulated insulin secretion. We found that pre-treatment with puerarin decreased the incidence of STZ-induced diabetes. Puerarin increased pancreatic β-cell mass via β-cell apoptosis inhibition in diabetic mice, and increased serum insulin, whereas it decreased blood glucose levels and improved glucose tolerance. In cultured islets and MIN6 cells, puerarin protected β-cell from cobalt chloride (CoCl2)-induced apoptosis and restored the impaired capacity of glucose-stimulated insulin secretion. Puerarin protection of β-cell survival involved the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. In conclusion, puerarin protects pancreatic β-cell function and survival via direct effects on β-cells, and its protection of β-cell survival is mediated by the PI3K/Akt pathway. As a safe natural plant extraction, puerarin might serve as a preventive and/or therapeutic approach for diabetes.

Download Full-text

Increased Pancreatic β-Cell Proliferation Mediated by CREB Binding Protein Gene Activation

Molecular and Cellular Biology ◽

10.1128/mcb.02353-05 ◽

2006 ◽

Vol 26 (20) ◽

pp. 7747-7759 ◽

Cited By ~ 66

Author(s):

Mehboob A. Hussain ◽

Delia L. Porras ◽

Matthew H. Rowe ◽

Jason R. West ◽

Woo-Jin Song ◽

...

Keyword(s):

Cell Proliferation ◽

Insulin Secretion ◽

Gene Activation ◽

Phosphorylation Site ◽

Creb Binding Protein ◽

Wild Type ◽

Β Cells ◽

Β Cell ◽

Glucose Stimulated Insulin Secretion

ABSTRACT The cyclic AMP (cAMP) signaling pathway is central in β-cell gene expression and function. In the nucleus, protein kinase A (PKA) phosphorylates CREB, resulting in recruitment of the transcriptional coactivators p300 and CREB binding protein (CBP). CBP, but not p300, is phosphorylated at serine 436 in response to insulin action. CBP phosphorylation disrupts CREB-CBP interaction and thus reduces nuclear cAMP action. To elucidate the importance of the cAMP-PKA-CREB-CBP pathway in pancreatic β cells specifically at the nuclear level, we have examined mutant mice lacking the insulin-dependent phosphorylation site of CBP. In these mice, the CREB-CBP interaction is enhanced in both the absence and presence of cAMP stimulation. We found that islet and β-cell masses were increased twofold, while pancreas weights were not different from the weights of wild-type littermates. β-Cell proliferation was increased both in vivo and in vitro in isolated islet cultures. Surprisingly, glucose-stimulated insulin secretion from perfused, isolated mutant islets was reduced. However, β-cell depolarization with KCl induced similar levels of insulin release from mutant and wild-type islets, indicating normal insulin synthesis and storage. In addition, transcripts of pgc1a, which disrupts glucose-stimulated insulin secretion, were also markedly elevated. In conclusion, sustained activation of CBP-responsive genes results in increased β-cell proliferation. In these β cells, however, glucose-stimulated insulin secretion was diminished, resulting from concomitant CREB-CBP-mediated pgc1a gene activation.

Download Full-text

Nuclear Factor Y in Male Mouse pancreatic β-cells Plays a Crucial Role in Glucose Homeostasis by Regulating β-Cell Mass and Insulin Secretion

10.2337/figshare.14547255.v1 ◽

2021 ◽

Author(s):

Yin Liu ◽

Siyuan He ◽

Ruixue Zhou ◽

Xueping Zhang ◽

Shanshan Yang ◽

...

Keyword(s):

Cell Proliferation ◽

Insulin Secretion ◽

Cell Mass ◽

Physiological Role ◽

Nuclear Factor ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Nuclear Factor Y

Download Full-text

Arachidonic acid, palmitic acid and glucose are important for the modulation of clonal pancreatic β-cell insulin secretion, growth and functional integrity

Clinical Science ◽

10.1042/cs20030261 ◽

2004 ◽

Vol 106 (2) ◽

pp. 191-199 ◽

Cited By ~ 44

Author(s):

Gordon DIXON ◽

John NOLAN ◽

Neville H. McCLENAGHAN ◽

Peter R. FLATT ◽

Philip NEWSHOLME

Keyword(s):

Nitric Oxide ◽

Fatty Acids ◽

Cell Proliferation ◽

Arachidonic Acid ◽

Insulin Secretion ◽

Type Ii Diabetes ◽

Cell Mass ◽

Type Ii ◽

Β Cells ◽

Β Cell

Insulin-resistant states such as obesity can result in an increase in the function and mass of pancreatic β-cells, so that insulin secretion is up-regulated and Type II diabetes does not develop. However, expansion of β-cell mass is not indefinite and may well decrease with time. Changes in circulating concentrations of nutritional factors, such as fatty acids and/or glucose, may lead to a reduction in β-cell mass in vivo. Few previous studies have attempted to explore the interplay between glucose, amino acids and fatty acids with respect to β-cell mass and functional integrity. In the present study, we demonstrate that culture of clonal BRIN-BD11 cells for 24 h with the polyunsaturated fatty acid arachidonic acid (AA) increased β-cell proliferation and enhanced alanine-stimulated insulin secretion. These effects of AA were associated with significant decreases in the cellular consumption of D-glucose and L-alanine as well as decreased rates of production of nitric oxide and ammonia. Conversely 24 h exposure to the saturated fatty acid palmitic acid (PA) was found to decrease β-cell viability (by increasing apoptosis), increase the intracellular concentration of triacylglycerol (triglyceride), while inhibiting alanine-stimulated insulin secretion. These effects of PA were associated with significant increases in D-glucose and L-glutamine consumption as well as nitric oxide and ammonia production. However, L-alanine consumption was decreased in the presence of PA. The effects of AA, but not PA, were additionally dependent on glucose concentration. These studies indicate that AA may have a critical role in maintaining the appropriate mass and function of islet β-cells by influencing rates of cell proliferation and insulin secretion. This regulatory effect may be compromised by high circulating levels of glucose and/or PA, both of which are elevated in Type II diabetes and may impact upon dysfunctional and apoptotic intracellular events in the β-cell.

Download Full-text

Hypoxylonol F Isolated from Annulohypoxylon annulatum Improves Insulin Secretion by Regulating Pancreatic β-cell Metabolism

Biomolecules ◽

10.3390/biom9080335 ◽

2019 ◽

Vol 9 (8) ◽

pp. 335 ◽

Cited By ~ 1

Author(s):

Dahae Lee ◽

Buyng Su Hwang ◽

Pilju Choi ◽

Taejung Kim ◽

Youngseok Kim ◽

...

Keyword(s):

Insulin Secretion ◽

Molecular Mechanisms ◽

Cell Metabolism ◽

Peroxisome Proliferator ◽

Pancreatic Β Cell ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Peroxisome Proliferator Activated Receptor ◽

Glucose Stimulated Insulin Secretion

Insulin plays a key role in glucose homeostasis and is hence used to treat hyperglycemia, the main characteristic of diabetes mellitus. Annulohypoxylon annulatum is an inedible ball-shaped wood-rotting fungus, and hypoxylon F is one of the major compounds of A. annulatum. The aim of this study is to evaluate the effects of hypoxylonol F isolated from A. annulatum on insulin secretion in INS-1 pancreatic β-cells and demonstrate the molecular mechanisms involved. Glucose-stimulated insulin secretion (GSIS) values were evaluated using a rat insulin ELISA kit. Moreover, the expression of proteins related to pancreatic β-cell metabolism and insulin secretion was evaluated using Western blotting. Hypoxylonol F isolated from A. annulatum was found to significantly enhance glucose-stimulated insulin secretion without inducing cytotoxicity. Additionally, hypoxylonol F enhanced insulin receptor substrate-2 (IRS-2) levels and activated the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway. Interestingly, it also modulated the expression of peroxisome proliferator-activated receptor γ (PPARγ) and pancreatic and duodenal homeobox 1 (PDX-1). Our findings showed that A. annulatum and its bioactive compounds are capable of improving insulin secretion by pancreatic β-cells. This suggests that A. annulatum can be used as a therapeutic agent to treat diabetes.

Download Full-text