scholarly journals A putative long noncoding RNA-encoded micropeptide maintains cellular homeostasis in pancreatic β-cells

2020 ◽  
Author(s):  
Mark Li ◽  
Fan Shao ◽  
Qingwen Qian ◽  
Wenjie Yu ◽  
Zeyuan Zhang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Cell Function ◽  
Transmembrane Domain ◽  
Critical Role ◽  
Human Pancreas ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells

ABSTRACTMicropeptides (microproteins) encoded by transcripts previously annotated as long noncoding RNA (IncRNAs) are emerging as important mediators of fundamental biological processes in health and disease. Here we applied two computational tools to identify putative micropeptides encoded by lncRNAs that are expressed in the human pancreas. We experimentally verified one such micropeptide encoded by a β-cell- and neural cell-enriched lncRNA TUNAR (also known as TUNA, HI-LNC78 or LINC00617). We named this highly conserved 48-amino-acid micropeptide Beta cell- and Neural cell-regulin (BNLN). BNLN contains a single-pass transmembrane domain and localized at the endoplasmic reticulum in pancreatic β-cells. Overexpression of BNLN lowered ER calcium levels, increased cytosolic calcium levels, and maintained ER homeostasis in response to high glucose challenge. To determine the physiological and pathological roles of BNLN, we assessed the BNLN expression in islets from mice fed with a high-fat diet and a regular diet, and found that BNLN is suppressed by diet-induced obesity (DIO). Conversely, overexpression of BNLN elevated glucose-stimulated insulin secretion in INS-1 cells. Lastly, BNLN overexpression enhanced insulin secretion in islets from lean and obese mice as well as from humans. Taken together, our study provides the first evidence that lncRNA-encoded micropeptides play a critical role in pancreatic β-cell function and provides a foundation for future comprehensive analyses of micropeptide function and pathophysiological impact on diabetes.

scholarly journals Oxytocin signal contributes to the adaptative growth of islets during gestation

2021 ◽  
Author(s):  
Ping Gu ◽  
Yuege Lin ◽  
Qi Wan ◽  
Dongming Su ◽  
Qun Shu
Keyword(s):  
Insulin Secretion ◽  
Pregnant Women ◽  
Cell Function ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Cell Adaptation ◽  
Β Cell Function ◽  
Insulinoma Cells

Background: Increased insulin production and secretion by pancreatic β-cells are important for ensuring the high insulin demand during gestation. However, the underlying mechanism of β-cell adaptation during gestation or in gestational diabetes mellitus (GDM) remains unclear. Oxytocin is an important physiological hormone in gestation and delivery, and it also contributes to the maintenance of β-cell function. The aim of this study was to investigate the role of oxytocin in β-cell adaptation during pregnancy. Methods: The relationship between the blood oxytocin level and pancreatic β-cell function in patients with GDM and healthy pregnant women was investigated. Gestating and non-gestating mice were used to evaluate the in vivo effect of oxytocin signal on β-cells during pregnancy. In vitro experiments were performed on INS-1 insulinoma cells. Results: The blood oxytocin levels were lower in patients with GDM than in healthy pregnant women and were associated with impaired pancreatic β-cell function. Acute administration of oxytocin increased insulin secretion in both gestating and non-gestating mice. A three-week oxytocin treatment promoted the proliferation of pancreatic β-cells and increased the β-cell mass in gestating but not non-gestating mice. Antagonism of oxytocin receptors by atosiban impaired insulin secretion and induced GDM in gestating but not non-gestating mice. Oxytocin enhanced glucose-stimulated insulin secretion, activated the mitogen-activated protein kinase pathway, and promoted cell proliferation in INS-1 cells. Conclusions: These findings provide strong evidence that oxytocin is needed for β-cell adaptation during pregnancy to maintain β-cell function, and lack of oxytocin could be associated with the risk of GDM.

scholarly journals Downregulation of lncRNA TUG1 Affects Apoptosis and Insulin Secretion in Mouse Pancreatic β Cells

2015 ◽  
Vol 35 (5) ◽  
pp. 1892-1904 ◽  
Author(s):  
Dan-dan Yin ◽  
Er-bao Zhang ◽  
Liang-hui You ◽  
Ning Wang ◽  
Lin-tao Wang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Annexin V ◽  
Pancreatic Tissue ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Lncrna Tug1

Background: Increasing evidence indicates that long noncoding RNAs (IncRNAs) perform specific biological functions in diverse processes. Recent studies have reported that IncRNAs may be involved in β cell function. The aim of this study was to characterize the role of IncRNA TUG1 in mouse pancreatic β cell functioning both in vitro and in vivo. Methods: qRT-PCR analyses were performed to detect the expression of lncRNA TUG1 in different tissues. RNAi, MTT, TUNEL and Annexin V-FITC assays and western blot, GSIS, ELISA and immunochemistry analyses were performed to detect the effect of lncRNA TUG1 on cell apoptosis and insulin secretion in vitro and in vivo. Results: lncRNA TUG1 was highly expressed in pancreatic tissue compared with other organ tissues, and expression was dynamically regulated by glucose in Nit-1 cells. Knockdown of lncRNA TUG1 expression resulted in an increased apoptosis ratio and decreased insulin secretion in β cells both in vitro and in vivo . Immunochemistry analyses suggested decreased relative islet area after treatment with lncRNA TUG1 siRNA. Conclusion: Downregulation of lncRNA TUG1 expression affected apoptosis and insulin secretion in pancreatic β cells in vitro and in vivo. lncRNA TUG1 may represent a factor that regulates the function of pancreatic β cells.

scholarly journals IL-1β reciprocally regulates chemokine and insulin secretion in pancreatic β-cells via NF-κB

2015 ◽  
Vol 309 (8) ◽  
pp. E715-E726 ◽  
Author(s):  
Susan J. Burke ◽  
Krisztian Stadler ◽  
Danhong Lu ◽  
Evanna Gleason ◽  
Anna Han ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Insulin Secretion ◽  
Transcriptional Activity ◽  
Cell Function ◽  
Inflammatory Responses ◽  
Cell Mass ◽  
Negative Regulator ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells

Proinflammatory cytokines impact islet β-cell mass and function by altering the transcriptional activity within pancreatic β-cells, producing increases in intracellular nitric oxide abundance and the synthesis and secretion of immunomodulatory proteins such as chemokines. Herein, we report that IL-1β, a major mediator of inflammatory responses associated with diabetes development, coordinately and reciprocally regulates chemokine and insulin secretion. We discovered that NF-κB controls the increase in chemokine transcription and secretion as well as the decrease in both insulin secretion and proliferation in response to IL-1β. Nitric oxide production, which is markedly elevated in pancreatic β-cells exposed to IL-1β, is a negative regulator of both glucose-stimulated insulin secretion and glucose-induced increases in intracellular calcium levels. By contrast, the IL-1β-mediated production of the chemokines CCL2 and CCL20 was not influenced by either nitric oxide levels or glucose concentration. Instead, the synthesis and secretion of CCL2 and CCL20 in response to IL-1β were dependent on NF-κB transcriptional activity. We conclude that IL-1β-induced transcriptional reprogramming via NF-κB reciprocally regulates chemokine and insulin secretion while also negatively regulating β-cell proliferation. These findings are consistent with NF-κB as a major regulatory node controlling inflammation-associated alterations in islet β-cell function and mass.

scholarly journals Targeting Mitochondrial Calcium Uptake with the Natural Flavonol Kaempferol, to Promote Metabolism/Secretion Coupling in Pancreatic β-cells

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 538 ◽  
Author(s):  
Flavien Bermont ◽  
Aurelie Hermant ◽  
Romy Benninga ◽  
Christian Chabert ◽  
Guillaume Jacot ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Calcium Uptake ◽  
Cell Function ◽  
Intervention Strategy ◽  
Mitochondrial Calcium ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Insulin Secreting Cells ◽  
Mitochondrial Calcium Uptake

Pancreatic β-cells secrete insulin to lower blood glucose, following a meal. Maintenance of β-cell function is essential to preventing type 2 diabetes. In pancreatic β-cells, mitochondrial matrix calcium is an activating signal for insulin secretion. Recently, the molecular identity of the mitochondrial calcium uniporter (MCU), the transporter that mediates mitochondrial calcium uptake, was revealed. Its role in pancreatic β-cell signal transduction modulation was clarified, opening new perspectives for intervention. Here, we investigated the effects of a mitochondrial Ca2+-targeted nutritional intervention strategy on metabolism/secretion coupling, in a model of pancreatic insulin-secreting cells (INS-1E). Acute treatment of INS-1E cells with the natural plant flavonoid and MCU activator kaempferol, at a low micromolar range, increased mitochondrial calcium rise during glucose stimulation, without affecting the expression level of the MCU and with no cytotoxicity. Enhanced mitochondrial calcium rises potentiated glucose-induced insulin secretion. Conversely, the MCU inhibitor mitoxantrone inhibited mitochondrial Ca2+ uptake and prevented both glucose-induced insulin secretion and kaempferol-potentiated effects. The kaempferol-dependent potentiation of insulin secretion was finally validated in a model of a standardized pancreatic human islet. We conclude that the plant product kaempferol activates metabolism/secretion coupling in insulin-secreting cells by modulating mitochondrial calcium uptake.

scholarly journals Circulating LncRNAs Analysis in Patients with Type 2 Diabetes Reveals Novel Genes Influencing Glucose Metabolism and Islet β-Cell Function

2018 ◽  
Vol 46 (1) ◽  
pp. 335-350 ◽  
Author(s):  
Yuting Ruan ◽  
Nie Lin ◽  
Qiang Ma ◽  
Rongping Chen ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Cell Function ◽  
Diabetic Patients ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Min6 Cells ◽  
Β Cell Function

Background/Aims: The islet is an important endocrine organ to secrete insulin to regulate the metabolism of glucose and maintain the stability of blood glucose. Long noncoding RNAs (lncRNAs) are involved in a variety of biological functions and play key roles in many diseases, including type 2 diabetes (T2D). The aim of this study was to determine whether lncRNA-p3134 is associated with glucose metabolism and insulin signaling in pancreatic β cells. Methods: LncRNA microarray technology was used to identify the differentially expressed circulating lncRNAs in T2D patients. RT-PCR analyses were performed to determine the expression of lncRNA-p3134 in 30 pairs of diabetic and non-diabetic patients. The correlation of lncRNA-p3134 to clinical data from T2D patients was analyzed. LncRNA-p3134 was overexpressed in Min6 cells and db/db mice by adenovirus-mediated technology. CCK-8, TUNEL, Western blot, glucose-stimulated insulin secretion (GSIS), ELISAs and immunochemistry were performed to determine the effect of lncRNA-p3134 on proliferation, apoptosis and insulin secretion both in vitro and vivo. Results: The circulating level of lncRNA-p3134 was higher in diabetic patients than in non-diabetic controls and was correlated with fasting blood glucose and HOMA-β levels. The lncRNA-p3134 had risen by 4 times in serum exosomes but nearly unchanged in exosome-free samples. The secretion of lncRNA-p3134 was dynamically modulated by glucose in both Min6 cells and isolated mouse islet cells. LncRNA-p3134 positively regulate GSIS through promoting of key regulators (Pdx-1, MafA, GLUT2 and Tcf7l2) in β cells. In addition, the overexpression of lncRNA-p3134 resulted in a decreased apoptosis ratio and partially reversed the glucotoxicity effects on GSIS function in Min6 cells. The restoration of insulin synthesis and secretion the increase of the insulin positive cells areas by upregulation of lncRNA-p3134 in db/db mice confirmed the compensatory role of lncRNA-p3134 to preserve β-cell function. Furthermore, a protective effect of lncRNA-p3134 on GSIS by positive modulation of PI3K/Akt/mTOR signaling was also confirmed. After blocking the PI3K/AKT signals with their specific inhibitor, the effect of overexpressed lncRNA-p3134 on insulin secretion was obviously attenuated. Conclusion: Taken together, the results of this study provide new insights into lncRNA-p3134 regulation in pancreatic β cells and provide a better understanding of novel mechanism of glucose homeostasis.

scholarly journals Identification and Isolation of Active Compounds from Astragalus membranaceus that Improve Insulin Secretion by Regulating Pancreatic β-Cell Metabolism

Biomolecules ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 618 ◽  
Author(s):  
Dahae Lee ◽  
Da Lee ◽  
Sungyoul Choi ◽  
Jin Lee ◽  
Dae Jang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Cell Metabolism ◽  
Astragalus Membranaceus ◽  
Peroxisome Proliferator ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Peroxisome Proliferator Activated Receptor ◽  
High Blood Glucose

In type 2 diabetes (T2D), insufficient secretion of insulin from the pancreatic β-cells contributes to high blood glucose levels, associated with metabolic dysregulation. Interest in natural products to complement or replace existing antidiabetic medications has increased. In this study, we examined the effect of Astragalus membranaceus extract (ASME) and its compounds 1–9 on glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. ASME and compounds 1–9 isolated from A. membranaceus stimulated insulin secretion in INS-1 cells without inducing cytotoxicity. A further experiment showed that compounds 2, 3, and 5 enhanced the phosphorylation of total insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), and Akt, and activated pancreatic and duodenal homeobox-1 (PDX-1) and peroxisome proliferator-activated receptor-γ (PPAR-γ), which are associated with β-cell function and insulin secretion. The data suggest that two isoflavonoids (2 and 3) and a nucleoside (compound 5), isolated from the roots of A. membranaceus, have the potential to improve insulin secretion in β-cells, representing the first step towards the development of potent antidiabetic drugs.

scholarly journals A Putative Long noncoding RNA‐encoded Micropeptide Maintains Cellular Homeostasis in Pancreatic β‐cells

2021 ◽  
Vol 35 (S1) ◽  
Author(s):  
Fan Shao ◽  
Mark Li ◽  
Qingwen Qian ◽  
Zeyuan Zhang ◽  
Dan Su ◽  
...  
Keyword(s):  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Cellular Homeostasis

scholarly journals RFX6-mediated dysregulation defines human β cell dysfunction in early type 2 diabetes

2021 ◽  
Author(s):  
John T Walker ◽  
Diane C Saunders ◽  
Vivek Rai ◽  
Chunhua Dai ◽  
Peter Orchard ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Association Studies ◽  
Critical Role ◽  
Regulatory Elements ◽  
Genome Wide Association Studies ◽  
Β Cells ◽  
Β Cell ◽  
Gene Regulatory

A hallmark of type 2 diabetes (T2D), a major cause of world-wide morbidity and mortality, is dysfunction of insulin-producing pancreatic islet β cells. T2D genome-wide association studies (GWAS) have identified hundreds of signals, mostly in the non-coding genome and overlapping β cell regulatory elements, but translating these into biological mechanisms has been challenging. To identify early disease-driving events, we performed single cell spatial proteomics, sorted cell transcriptomics, and assessed islet physiology on pancreatic tissue from short-duration T2D and control donors. Here, through integrative analyses of these diverse modalities, we show that multiple gene regulatory modules are associated with early-stage T2D β cell-intrinsic defects. One notable example is the transcription factor RFX6, which we show is a highly connected β cell hub gene that is reduced in T2D and governs a gene regulatory network associated with insulin secretion defects and T2D GWAS variants. We validated the critical role of RFX6 in β cells through direct perturbation in primary human islets followed by physiological and single nucleus multiome profiling, which showed reduced dynamic insulin secretion and large-scale changes in the β cell transcriptome and chromatin accessibility landscape. Understanding the molecular mechanisms of complex, systemic diseases necessitates integration of signals from multiple molecules, cells, organs, and individuals and thus we anticipate this approach will be a useful template to identify and validate key regulatory networks and master hub genes for other diseases or traits with GWAS data.

scholarly journals NKX6.1 transcription factor: a crucial regulator of pancreatic β cell development, identity, and proliferation

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Idil I. Aigha ◽  
Essam M. Abdelalim
Keyword(s):  
Transcription Factor ◽  
Cell Function ◽  
Disease Modeling ◽  
Critical Role ◽  
Cell Mass ◽  
Cell Development ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function

Abstract Understanding the biology underlying the mechanisms and pathways regulating pancreatic β cell development is necessary to understand the pathology of diabetes mellitus (DM), which is characterized by the progressive reduction in insulin-producing β cell mass. Pluripotent stem cells (PSCs) can potentially offer an unlimited supply of functional β cells for cellular therapy and disease modeling of DM. Homeobox protein NKX6.1 is a transcription factor (TF) that plays a critical role in pancreatic β cell function and proliferation. In human pancreatic islet, NKX6.1 expression is exclusive to β cells and is undetectable in other islet cells. Several reports showed that activation of NKX6.1 in PSC-derived pancreatic progenitors (MPCs), expressing PDX1 (PDX1+/NKX6.1+), warrants their future commitment to monohormonal β cells. However, further differentiation of MPCs lacking NKX6.1 expression (PDX1+/NKX6.1−) results in an undesirable generation of non-functional polyhormonal β cells. The importance of NKX6.1 as a crucial regulator in MPC specification into functional β cells directs attentions to further investigating its mechanism and enhancing NKX6.1 expression as a means to increase β cell function and mass. Here, we shed light on the role of NKX6.1 during pancreatic β cell development and in directing the MPCs to functional monohormonal lineage. Furthermore, we address the transcriptional mechanisms and targets of NKX6.1 as well as its association with diabetes.

scholarly journals Nitric oxide interacts with cholinoceptors to modulate insulin secretion by pancreatic β cells

2020 ◽  
Vol 472 (10) ◽  
pp. 1469-1480
Author(s):  
Bashair M. Mussa ◽  
Ankita Srivastava ◽  
Abdul Khader Mohammed ◽  
Anthony J. M. Verberne
Keyword(s):  
Nitric Oxide ◽  
Insulin Secretion ◽  
Cell Viability ◽  
Combined Treatment ◽  
No Production ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Tnf Α ◽  
Ifn Γ

Abstract Dysfunction of the pancreatic β cells leads to several chronic disorders including diabetes mellitus. Several mediators and mechanisms are known to be involved in the regulation of β cell secretory function. In this study, we propose that cytokine-induced nitric oxide (NO) production interacts with cholinergic mechanisms to modulate insulin secretion from pancreatic β cells. Using a rat insulinoma cell line INS-1, we demonstrated that β cell viability decreases significantly in the presence of SNAP (NO donor) in a concentration- and time-dependent manner. Cell viability was also found to be decreased in the presence of a combined treatment of SNAP with SMN (muscarinic receptor antagonist). We then investigated the impact of these findings on insulin secretion and found a significant reduction in glucose uptake by INS-1 cells in the presence of SNAP and SMN as compared with control. Nitric oxide synthase 3 gene expression was found to be significantly reduced in response to combined treatment with SNAP and SMN suggesting an interaction between the cholinergic and nitrergic systems. The analysis of gene and protein expression further pin-pointed the involvement of M3 muscarinic receptors in the cholinergic pathway. Upon treatment with cytokines, reduced cell viability was observed in the presence of TNF-α and IFN-γ. A significant reduction in insulin secretion was also noted after treatment with TNF-α and IFN-γ and IL1-β. The findings of the present study have shown for the first time that the inhibition of the excitatory effects of cholinergic pathways on glucose-induced insulin secretion may cause β cell injury and dysfunction of insulin secretion in response to cytokine-induced NO production.

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