scholarly journals m6A mRNA Methylation Controls Functional Maturation in Neonatal Murine β Cells

2020 ◽  
Author(s):  
Ada Admin ◽  
Yanqiu Wang ◽  
Jiajun Sun ◽  
Zhen Lin ◽  
Weizhen Zhang ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Cell Mass ◽  
Rna Modification ◽  
Β Cells ◽  
Β Cell ◽  
Functional Maturation ◽  
Mass Expansion ◽  
Endocrine Progenitors

<a>m<sup>6</sup>A RNA modification is essential during embryonic development of various organs; however, its role in embryonic and early postnatal islet development remains unknown.</a><a></a><a> </a>Mice in which RNA methyltransferase-like 3/14 (Mettl3/14) were deleted in Ngn3<sup>+</sup> endocrine progenitors (<i>Mettl3/14<sup>nKO</sup></i>) developed hyperglycemia and hypo-insulinemia at 2 weeks after birth. <a></a><a>We found that Mettl3/14 specifically regulated both functional maturation and mass expansion of neonatal</a><a></a><a> β cell</a>s before weaning. Transcriptome and m<sup>6</sup>A methylome analyses provided m<sup>6</sup>A-dependent mechanisms in regulating<a> cell</a> identity, insulin secretion and proliferation in neonatal<a></a><a> </a><a></a><a>β</a> cells.<a></a><a> Importantly, we found that Mettl3/14 were dispensable for β cell differentiation, but directly regulated essential transcriptional factor MafA expression</a><a> at least partially via modulating its mRNA stability and failure to maintain this modification impacted the ability to fulfill β cell functional maturity. </a>In both diabetic <i>db/db</i> mice and type 2 diabetes patients, decreased Mettl3/14 expression in <a></a><a>β</a> cells were observed, suggesting its possible role in type 2 diabetes. Our stud­­­­­­<sub>­­­</sub>y unraveled the essential role of Mettl3/14 in neonatal β cell development and functional maturation, both of which determined functional β cell mass and glycemic control in adulthood.<b></b>

scholarly journals m6A mRNA Methylation Controls Functional Maturation in Neonatal Murine β Cells

2020 ◽  
Author(s):  
Ada Admin ◽  
Yanqiu Wang ◽  
Jiajun Sun ◽  
Zhen Lin ◽  
Weizhen Zhang ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Cell Mass ◽  
Rna Modification ◽  
Β Cells ◽  
Β Cell ◽  
Functional Maturation ◽  
Mass Expansion ◽  
Endocrine Progenitors

<a>m<sup>6</sup>A RNA modification is essential during embryonic development of various organs; however, its role in embryonic and early postnatal islet development remains unknown.</a><a></a><a> </a>Mice in which RNA methyltransferase-like 3/14 (Mettl3/14) were deleted in Ngn3<sup>+</sup> endocrine progenitors (<i>Mettl3/14<sup>nKO</sup></i>) developed hyperglycemia and hypo-insulinemia at 2 weeks after birth. <a></a><a>We found that Mettl3/14 specifically regulated both functional maturation and mass expansion of neonatal</a><a></a><a> β cell</a>s before weaning. Transcriptome and m<sup>6</sup>A methylome analyses provided m<sup>6</sup>A-dependent mechanisms in regulating<a> cell</a> identity, insulin secretion and proliferation in neonatal<a></a><a> </a><a></a><a>β</a> cells.<a></a><a> Importantly, we found that Mettl3/14 were dispensable for β cell differentiation, but directly regulated essential transcriptional factor MafA expression</a><a> at least partially via modulating its mRNA stability and failure to maintain this modification impacted the ability to fulfill β cell functional maturity. </a>In both diabetic <i>db/db</i> mice and type 2 diabetes patients, decreased Mettl3/14 expression in <a></a><a>β</a> cells were observed, suggesting its possible role in type 2 diabetes. Our stud­­­­­­<sub>­­­</sub>y unraveled the essential role of Mettl3/14 in neonatal β cell development and functional maturation, both of which determined functional β cell mass and glycemic control in adulthood.<b></b>

scholarly journals Adaptive β-cell proliferation increases early in high-fat feeding in mice, concurrent with metabolic changes, with induction of islet cyclin D2 expression

2013 ◽  
Vol 305 (1) ◽  
pp. E149-E159 ◽  
Author(s):  
Rachel E. Stamateris ◽  
Rohit B. Sharma ◽  
Douglas A. Hollern ◽  
Laura C. Alonso
Keyword(s):  
Cell Proliferation ◽  
Cell Mass ◽  
Extended Period ◽  
Time Frame ◽  
High Fat ◽  
Β Cells ◽  
Β Cell ◽  
Cyclin D2 ◽  
Mass Expansion

Type 2 diabetes (T2D) is caused by relative insulin deficiency, due in part to reduced β-cell mass ( 11 , 62 ). Therapies aimed at expanding β-cell mass may be useful to treat T2D ( 14 ). Although feeding rodents a high-fat diet (HFD) for an extended period (3–6 mo) increases β-cell mass by inducing β-cell proliferation ( 16 , 20 , 53 , 54 ), evidence suggests that adult human β-cells may not meaningfully proliferate in response to obesity. The timing and identity of the earliest initiators of the rodent compensatory growth response, possible therapeutic targets to drive proliferation in refractory human β-cells, are not known. To develop a model to identify early drivers of β-cell proliferation, we studied mice during the first week of HFD exposure, determining the onset of proliferation in the context of diet-related physiological changes. Within the first week of HFD, mice consumed more kilocalories, gained weight and fat mass, and developed hyperglycemia, hyperinsulinemia, and glucose intolerance due to impaired insulin secretion. The β-cell proliferative response also began within the first week of HFD feeding. Intriguingly, β-cell proliferation increased before insulin resistance was detected. Cyclin D2 protein expression was increased in islets by day 7, suggesting it may be an early effector driving compensatory β-cell proliferation in mice. This study defines the time frame and physiology to identify novel upstream regulatory signals driving mouse β-cell mass expansion, in order to explore their efficacy, or reasons for inefficacy, in initiating human β-cell proliferation.

scholarly journals A Sustained Activation of Pancreatic NMDARs Is a Novel Factor of β-Cell Apoptosis and Dysfunction

Endocrinology ◽  
2017 ◽  
Vol 158 (11) ◽  
pp. 3900-3913 ◽  
Author(s):  
Xiao-Ting Huang ◽  
Shao-Jie Yue ◽  
Chen Li ◽  
Yan-Hong Huang ◽  
Qing-Mei Cheng ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Cell Apoptosis ◽  
Cell Function ◽  
Cell Mass ◽  
Nuclear Factor Κb ◽  
Β Cells ◽  
Β Cell ◽  
Stimulation Of ◽  
Sustained Activation

Abstract Type 2 diabetes, which features β-cell failure, is caused by the decrease of β-cell mass and insulin secretory function. Current treatments fail to halt the decrease of functional β-cell mass. Strategies to prevent β-cell apoptosis and dysfunction are highly desirable. Recently, our group and others have reported that blockade of N-methyl-d-aspartate receptors (NMDARs) in the islets has been proposed to prevent the progress of type 2 diabetes through improving β-cell function. It suggests that a sustained activation of the NMDARs may exhibit deleterious effect on β-cells. However, the exact functional impact and mechanism of the sustained NMDAR stimulation on islet β-cells remains unclear. Here, we identify a sustained activation of pancreatic NMDARs as a novel factor of apoptotic β-cell death and function. The sustained treatment with NMDA results in an increase of intracellular [Ca2+] and reactive oxygen species, subsequently induces mitochondrial membrane potential depolarization and a decrease of oxidative phosphorylation expression, and then impairs the mitochondrial function of β-cells. NMDA specifically induces the mitochondrial-dependent pathway of apoptosis in β-cells through upregulation of the proapoptotic Bim and Bax, and downregulation of antiapoptotic Bcl-2. Furthermore, a sustained stimulation of NMDARs impairs β-cell insulin secretion through decrease of pancreatic duodenal homeobox-1 (Pdx-1) and adenosine triphosphate synthesis. The activation of nuclear factor–κB partly contributes to the reduction of Pdx-1 expression induced by overstimulation of NMDARs. In conclusion, we show that the sustained stimulation of NMDARs is a novel mediator of apoptotic signaling and β-cell dysfunction, providing a mechanistic insight into the pathological role of NMDARs activation in diabetes.

Arachidonic acid fights palmitate: new insights into fatty acid toxicity in β-cells

2010 ◽  
Vol 120 (5) ◽  
pp. 179-181 ◽  
Author(s):  
Henrik Ortsäter
Keyword(s):  
Type 2 Diabetes ◽  
Arachidonic Acid ◽  
Fatty Acid ◽  
Saturated Fatty Acids ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Self Protection

Saturated fatty acids are toxic to pancreatic β-cells. By inducing apoptosis, they contribute to a decrease in β-cell mass, a hallmark of Type 2 diabetes. In the present issue of Clinical Science, Keane and co-workers show that the polyunsaturated fatty acid arachidonic acid protects the β-cell against the toxic effects of palmitate. As Type 2 diabetes is characterized by subclinical inflammation, and arachidonic acid and metabolites thereof are produced during states of inflammation, it is possible that pancreatic β-cells use arachidonic acid as a compound for self-protection.

scholarly journals β cell-specific deletion of HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase causes overt diabetes due to reduction of β cell mass and impaired insulin secretion

2020 ◽  
Author(s):  
Ada Admin ◽  
Shoko Takei ◽  
Shuichi Nagashima ◽  
Akihito Takei ◽  
Daisuke Yamamuro ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Coenzyme A ◽  
Cell Mass ◽  
Bzip Transcription Factor ◽  
Β Cells ◽  
Β Cell ◽  
Embryonic Pancreas ◽  
Endocrine Progenitors ◽  
Coenzyme A Reductase

Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), statins, which are used to prevent cardiovascular diseases, are associated with a modest increase in the risk of new-onset diabetes mellitus. To investigate the role of HMGCR in the development of β cells and glucose homeostasis, we deleted <i>Hmgcr</i> in a β cell-specific manner by using the Cre-loxP technique. Mice lacking <i>Hmgcr</i> in β cells (β-KO) exhibited hypoinsulinemic hyperglycemia as early as postnatal day 9 (P9) due to decreases in both β cell mass and insulin secretion. Ki67 positive cells were reduced in β-KO mice at P9, thus β cell mass reduction was caused by proliferation disorder immediately after birth. The mRNA expression of <i>neurogenin3 (Ngn3)</i>, which is transiently expressed in endocrine progenitors of the embryonic pancreas, was maintained despite a striking reduction in the expression of β cell-associated genes, such as <i>insulin</i>, <i>Pancreatic and duodenal homeobox 1</i> <i>(Pdx1)</i> and <i>MAF BZIP transcription factor A (</i><i>Mafa)</i> in the islets from β-KO mice. Histological analyses revealed dysmorphic islets with markedly reduced numbers of β cells, some of which were also positive for glucagon. In conclusion, HMGCR plays critical roles not only in insulin secretion but also in the development of β cells in mice.

scholarly journals Insulin: The Friend and the Foe in the Development of Type 2 Diabetes Mellitus

2020 ◽  
Vol 21 (5) ◽  
pp. 1770
Author(s):  
Nadia Rachdaoui
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Insulin Secretion ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Peripheral Insulin Resistance

Insulin, a hormone produced by pancreatic β-cells, has a primary function of maintaining glucose homeostasis. Deficiencies in β-cell insulin secretion result in the development of type 1 and type 2 diabetes, metabolic disorders characterized by high levels of blood glucose. Type 2 diabetes mellitus (T2DM) is characterized by the presence of peripheral insulin resistance in tissues such as skeletal muscle, adipose tissue and liver and develops when β-cells fail to compensate for the peripheral insulin resistance. Insulin resistance triggers a rise in insulin demand and leads to β-cell compensation by increasing both β-cell mass and insulin secretion and leads to the development of hyperinsulinemia. In a vicious cycle, hyperinsulinemia exacerbates the metabolic dysregulations that lead to β-cell failure and the development of T2DM. Insulin and IGF-1 signaling pathways play critical roles in maintaining the differentiated phenotype of β-cells. The autocrine actions of secreted insulin on β-cells is still controversial; work by us and others has shown positive and negative actions by insulin on β-cells. We discuss findings that support the concept of an autocrine action of secreted insulin on β-cells. The hypothesis of whether, during the development of T2DM, secreted insulin initially acts as a friend and contributes to β-cell compensation and then, at a later stage, becomes a foe and contributes to β-cell decompensation will be discussed.

scholarly journals The role of adipokines in β-cell failure of type 2 diabetes

2012 ◽  
Vol 216 (1) ◽  
pp. T37-T45 ◽  
Author(s):  
Simon J Dunmore ◽  
James E P Brown
Keyword(s):  
Type 2 Diabetes ◽  
Β Cells ◽  
Β Cell ◽  
Beneficial Effects ◽  
Published Evidence ◽  
Key Factor ◽  
Excessive Adiposity ◽  
Factor Α

β-Cell failure coupled with insulin resistance is a key factor in the development of type 2 diabetes. Changes in circulating levels of adipokines, factors released from adipose tissue, form a significant link between excessive adiposity in obesity and both aforementioned factors. In this review, we consider the published evidence for the role of individual adipokines on the function, proliferation, death and failure of β-cells, focusing on those reported to have the most significant effects (leptin, adiponectin, tumour necrosis factor α, resistin, visfatin, dipeptidyl peptidase IV and apelin). It is apparent that some adipokines have beneficial effects whereas others have detrimental properties; the overall contribution to β-cell failure of changed concentrations of adipokines in the blood of obese pre-diabetic subjects will be highly dependent on the balance between these effects and the interactions between the adipokines, which act on the β-cell via a number of intersecting intracellular signalling pathways. We emphasise the importance, and comparative dearth, of studies into the combined effects of adipokines on β-cells.

scholarly journals Hope and fear for new classes of type 2 diabetes drugs: is there preclinical evidence that incretin-based therapies alter pancreatic morphology?

2014 ◽  
Vol 221 (1) ◽  
pp. T43-T61 ◽  
Author(s):  
Benjamin J Lamont ◽  
Sofianos Andrikopoulos
Keyword(s):  
Type 2 Diabetes ◽  
Cell Mass ◽  
Preclinical Studies ◽  
Β Cells ◽  
Β Cell ◽  
Dipeptidyl Peptidase 4 ◽  
Dpp4 Inhibitors ◽  
Natural Progression ◽  
Glucagon Like Peptide 1

Incretin-based therapies appear to offer many advantages over other approaches for treating type 2 diabetes. Some preclinical studies have suggested that chronic activation of glucagon-like peptide 1 receptor (GLP1R) signalling in the pancreas may result in the proliferation of islet β-cells and an increase in β-cell mass. This provided hope that enhancing GLP1 action could potentially alter the natural progression of type 2 diabetes. However, to date, there has been no evidence from clinical trials suggesting that GLP1R agonists or dipeptidyl peptidase-4 (DPP4) inhibitors can increase β-cell mass. Nevertheless, while the proliferative capacity of these agents remains controversial, some studies have raised concerns that they could potentially contribute to the development of pancreatitis and hence increase the risk of pancreatic cancer. Currently, there are very limited clinical data to directly assess these potential benefits and risks of incretin-based therapies. However, a review of the preclinical studies indicates that incretin-based therapies probably have only a limited capacity to regenerate pancreatic β-cells, but may be useful for preserving any remaining β-cells in type 2 diabetes. In addition, the majority of preclinical evidence does not support the notion that GLP1R agonists or DPP4 inhibitors cause pancreatitis.

Could lncRNAs contribute to β-cell identity and its loss in Type 2 diabetes?

2013 ◽  
Vol 41 (3) ◽  
pp. 797-801 ◽  
Author(s):  
Timothy J. Pullen ◽  
Guy A. Rutter
Keyword(s):  
Type 2 Diabetes ◽  
Cell Mass ◽  
Cell Types ◽  
Human Populations ◽  
Β Cell ◽  
Cell Identity ◽  
Genome Wide ◽  
And Function

The progression of Type 2 diabetes is accompanied by diminishing islet β-cell mass and function. It has been proposed that β-cells are lost not only through apoptosis, but also by dedifferentiating into progenitor-like cells. There is therefore much interest in the mechanisms which define and maintain β-cell identity. The advent of genome-wide analyses of chromatin modifications has highlighted the role of epigenetic factors in determining cell identity. There is also evidence from both human populations and animal models for an epigenetic component in susceptibility to Type 2 diabetes. The mechanisms responsible for defining the epigenetic landscape in individual cell types are poorly understood, but there is growing evidence of a role for lncRNAs (long non-coding RNAs) in this process. In the present paper, we discuss some of the mechanisms through which lncRNAs may contribute to β-cell identity and Type 2 diabetes risk.

β-Cell compensation concomitant with adaptive endoplasmic reticulum stress and β-cell neogenesis in a diet-induced type 2 diabetes model

2019 ◽  
Vol 44 (12) ◽  
pp. 1355-1366 ◽  
Author(s):  
Hui Huang ◽  
Kaiyuan Yang ◽  
Rennian Wang ◽  
Woo Hyun Han ◽  
Sharee Kuny ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Endoplasmic Reticulum ◽  
Insulin Secretion ◽  
Cell Function ◽  
Cell Mass ◽  
Temporal Association ◽  
Adaptive Responses ◽  
Β Cells ◽  
Β Cell

Insulin-secreting pancreatic β-cells adapt to obesity-related insulin resistance via increases in insulin secretion and β-cell mass. Failed β-cell compensation predicts the onset of type 2 diabetes (T2D). However, the mechanisms of β-cell compensation are not fully understood. Our previous study reported changes in β-cell mass during the progression of T2D in the Nile rat (NR; Arvicanthis niloticus) fed standard chow. In the present study, we measured other β-cell adaptive responses, including glucose metabolism and β-cell insulin secretion in NRs at different ages, thus characterizing NR at 2 months as a model of β-cell compensation followed by decompensation at 6 months. We observed increased proinsulin secretion in the transition from compensation to decompensation, which is indicative of impaired insulin processing. Subsequently, we compared adaptive unfolded protein response in β-cells and demonstrated a positive role of endoplasmic reticulum (ER) chaperones in insulin secretion. In addition, the incidence of insulin-positive neogenic but not proliferative cells increased during the compensation phase, suggesting nonproliferative β-cell growth as a mechanism of β-cell mass adaptation. In contrast, decreased neogenesis and β-cell dedifferentiation were observed in β-cell dysfunction. Furthermore, the progression of T2D and pathophysiological changes of β-cells were prevented by increasing fibre content of the diet. Novelty Our study characterized a novel model for β-cell compensation with adaptive responses in cell function and mass. The temporal association of adaptive ER chaperones with blood insulin and glucose suggests upregulated chaperone capacity as an adaptive mechanism. β-Cell neogenesis but not proliferation contributes to β-cell mass adaptation.

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