scholarly journals A novel disease mechanism leading to the expression of a disallowed gene in the pancreatic beta-cell identified by non-coding, regulatory mutations controlling HK1

2021 ◽  
Author(s):  
Matthew N. Wakeling ◽  
Nick D. L. Owens ◽  
Jessica R. Hopkinson ◽  
Matthew B. Johnson ◽  
Jayne A.L. Houghton ◽  
...  
Keyword(s):  
Beta Cell ◽  
Pancreatic Beta Cells ◽  
De Novo ◽  
Regulatory Element ◽  
Pancreatic Beta Cell ◽  
Regulatory Region ◽  
Protein Product ◽  
Congenital Hyperinsulinism ◽  
Disease Mechanism ◽  
Regulatory Mutations

AbstractGene expression is tightly regulated with many genes exhibiting cell-specific silencing when their protein product would disrupt normal cellular function. This silencing is largely controlled by non-coding elements and their disruption might cause human disease. We performed gene-agnostic screening of the non-coding regions to discover new molecular causes of congenital hyperinsulinism. This identified 14 non-coding de novo mutations affecting a 42bp conserved region encompassed by a regulatory element in intron 2 of Hexokinase 1 (HK1), a pancreatic beta-cell disallowed gene. We demonstrated that these mutations resulted in expression of HK1 in the pancreatic beta-cells causing inappropriate insulin secretion and congenital hyperinsulinism. These mutations identify a regulatory region critical for cell-specific silencing. Importantly, this has revealed a new disease mechanism for non-coding mutations that cause inappropriate expression of a disallowed gene.

scholarly journals Update on the Protective Molecular Pathways Improving Pancreatic Beta-Cell Dysfunction

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Alessandra Puddu ◽  
Roberta Sanguineti ◽  
François Mach ◽  
Franco Dallegri ◽  
Giorgio Luciano Viviani ◽  
...  
Keyword(s):  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Cell Function ◽  
Pancreatic Beta Cell ◽  
Cell Mass ◽  
Beta Cell Mass ◽  
Beta Cell Dysfunction ◽  
Molecular Pathways ◽  
Cell Dysfunction

The primary function of pancreatic beta-cells is to produce and release insulin in response to increment in extracellular glucose concentrations, thus maintaining glucose homeostasis. Deficient beta-cell function can have profound metabolic consequences, leading to the development of hyperglycemia and, ultimately, diabetes mellitus. Therefore, strategies targeting the maintenance of the normal function and protecting pancreatic beta-cells from injury or death might be crucial in the treatment of diabetes. This narrative review will update evidence from the recently identified molecular regulators preserving beta-cell mass and function recovery in order to suggest potential therapeutic targets against diabetes. This review will also highlight the relevance for novel molecular pathways potentially improving beta-cell dysfunction.

scholarly journals High dose of histone deacetylase inhibitors affects insulin secretory mechanism of pancreatic beta cell line

2018 ◽  
Vol 52 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Eiji Yamato
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Cell Line ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
High Dose ◽  
Min6 Cells ◽  
Beta Cell Line ◽  
High Doses

Abstract Objective. Histone deacytylase inhibitors (HDACis) inhibit the deacetylation of the lysine residue of proteins, including histones, and regulate the transcription of a variety of genes. Recently, HDACis have been used clinically as anti-cancer drugs and possible anti-diabetic drugs. Even though HDACis have been proven to protect the cytokine-induced damage of pancreatic beta cells, evidence also shows that high doses of HDACis are cytotoxic. In the present study, we, therefore, investigated the eff ect of HDACis on insulin secretion in a pancreatic beta cell line. Methods. Pancreatic beta cells MIN6 were treated with selected HDACis (trichostatin A, TSA; valproic acid, VPA; and sodium butyrate, NaB) in medium supplemented with 25 mM glucose and 13% heat-inactivated fetal bovine serum (FBS) for indicated time intervals. Protein expression of Pdx1 and Mafa in MIN6 cells was demonstrated by immunohistochemistry and immunocytochemistry, expression of Pdx1 and Mafa genes was measured by quantitative RT-PCR method. Insulin release from MIN6 cells and insulin cell content were estimated by ELISA kit. Superoxide production in MIN6 cells was measured using a Total ROS/Superoxide Detection System. Results. TSA, VPA, and NaB inhibited the expression of Pdx1 and Mafa genes and their products. TSA treatment led to beta cell malfunction, characterized by enhanced insulin secretion at 3 and 9 mM glucose, but impaired insulin secretion at 15 and 25 mM glucose. Th us, TSA induced dysregulation of the insulin secretion mechanism. TSA also enhanced reactive oxygen species production in pancreatic beta cells. Conclusions. Our results showed that HDACis caused failure to suppress insulin secretion at low glucose concentrations and enhance insulin secretion at high glucose concentrations. In other words, when these HDACis are used clinically, high doses of HDACis may cause hypoglycemia in the fasting state and hyperglycemia in the fed state. When using HDACis, physicians should, therefore, be aware of the capacity of these drugs to modulate the insulin secretory capacity of pancreatic beta cells.

Catecholamine modulation of calcium currents in clonal pancreatic beta-cells

1989 ◽  
Vol 257 (6) ◽  
pp. C1171-C1176 ◽  
Author(s):  
H. H. Keahey ◽  
A. E. Boyd ◽  
D. L. Kunze
Keyword(s):  
Beta Cell ◽  
G Protein ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Calcium Influx ◽  
Pancreatic Beta Cell ◽  
Cytosolic Calcium ◽  
Calcium Currents ◽  
Secretory Process ◽  
Beta Cell Line

The mechanisms by which norepinephrine and epinephrine activate alpha 2-adrenergic receptors and inhibit insulin release from the pancreatic beta-cell (19, 21, 23) are not yet clear but may involve modulation at several sites. Because intracellular calcium has been implicated in the secretory process, it has been suggested that catecholamines may inhibit secretion by blocking calcium influx, thus reducing the free cytosolic calcium concentration (23). The present study examines the effects of epinephrine, norepinephrine, and clonidine on calcium current in an SV40-transformed hamster beta-cell line (HIT cells). Under voltage-clamp conditions, calcium currents were reversibly inhibited by norepinephrine, epinephrine, and clonidine in the low nanomolar range. The effects were blocked by 1) the alpha 2-antagonist yohimbine, 2) preincubation of the cells with pertussis toxin (PTX), and 3) guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), the nonhydrolyzable GDP analogue that competitively inhibits the interaction of GTP with G proteins. In contrast, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) caused irreversible blockade by catecholamines. These effects could not be overcome by adenosine 3',5'-cyclic monophosphate (cAMP), suggesting that the adenylate cyclase pathway is not involved in the G protein coupling with the channels. These studies show that catecholamines inhibit calcium currents in beta-cells through an alpha 2-adrenoreceptor PTX-sensitive G protein pathway and could inhibit insulin secretion by this mechanism.

scholarly journals The acquisition of an insulin-secreting phenotype by HGF-treated rat pancreatic ductal cells (ARIP) is associated with the development of susceptibility to cytokine-induced apoptosis

2005 ◽  
Vol 34 (2) ◽  
pp. 367-376 ◽  
Author(s):  
E Anastasi ◽  
C Santangelo ◽  
A Bulotta ◽  
F Dotta ◽  
B Argenti ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cell ◽  
Pancreatic Beta Cells ◽  
Interleukin 1 ◽  
Pancreatic Beta Cell ◽  
Necrosis Factor Alpha ◽  
Ductal Cells ◽  
Pancreatic Ductal Cells ◽  
Induced Apoptosis

The elucidation of mechanisms regulating the regeneration and survival of pancreatic beta cells has fundamental implications in the cell therapy of type 1 diabetes. The present study had the following three aims: 1. to investigate whether pancreatic ductal epithelial cells can be induced to differentiate into insulin-producing cells by exposing them to hepatocyte growth factor (HGF); 2. to characterize some of the molecular events leading to their differentiation toward a beta-cell-like phenotype; 3. to evaluate the susceptibility of newly differentiated insulin-secreting cells to cytokine-induced apoptosis, a mechanism of beta-cell destruction occurring in type 1 diabetes. We demonstrated that HGF-treated rat pancreatic ductal cell line (ARIP) cells acquired the capability to transcribe the insulin gene and translate its counterpart protein. HGF-treated cells also exhibited a glucose-dependent capability to secrete insulin into the cultured medium. Expression analysis of some of the genes regulating pancreatic beta-cell differentiation revealed a time-dependent transcription of neurogenin-3 and Neuro-D in response to HGF. Finally, we determined the susceptibility to proinflammatory cytokine (PTh1)-induced apoptosis by incubating HGF-treated and untreated ARIP cells with a cocktail of interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ). Such treatment induced apoptotic death, as determined by the TUNEL technique, in about 40% of HGF-treated, insulin-secreting ARIP cells, while untreated ARIP cells were resistant to PTh1-induced apoptosis. In conclusion, we showed that HGF promotes the differentiation of ARIP cells into pancreatic beta-cell-like cells, and that the differentiation toward an insulin-secreting phenotype is associated with the appearance of susceptibility to cytokine-induced apoptosis.

scholarly journals PCSK9 affects expression of key surface proteins in human pancreatic beta cells through intra- and extracellular regulatory circuits

2021 ◽  
Author(s):  
kevin Saitoski ◽  
Maria Ryaboshapkina ◽  
Ghaith Hamza ◽  
Andrew F Jarnuczak ◽  
claire berthault ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Beta Cell ◽  
Pancreatic Islets ◽  
Cell Line ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
Loss Of Function ◽  
Beta Cell Line ◽  
Gain And Loss

Aims/hypothesis: Proprotein convertase subtilisin/kexin 9 (PCSK9) is involved in the degradation of LDLR. However, PCSK9 can target other proteins in a cell-type specific manner. While PCSK9 has been detected in pancreatic islets, its expression in insulin-producing pancreatic beta cells is debated. Herein, we studied PCSK9 expression, regulation and function in the human pancreatic beta cell line EndoC-βH1. Methods: We assessed PCSK9 expression in mouse and human pancreatic islets, and in the pancreatic beta cell line EndoC-βH1. We also studied PCSK9 regulation by cholesterol, lipoproteins, Mevastatin, and by SREBPs transcription factors. To evaluate PCSK9 function in pancreatic beta cells, we performed PCSK9 gain-and loss-of-function experiments in EndoC-βH1 using siPCSK9 or recombinant PCSK9 treatments, respectively. Results: We demonstrate that PCSK9 is expressed and secreted by pancreatic beta cells. In EndoC-βH1 cells, PCSK9 expression is regulated by cholesterol and by SREBPs transcription factors. Importantly, PCSK9 knockdown results in multiple transcriptome, proteome and secretome deregulations and impaired insulin secretion. By gain- and loss-of- function experiments, we observed that PCSK9 regulates the expression levels of LDLR and VLDLR through an extracellular mechanism while CD36, PD-L1 and HLA-ABC are regulated through an intracellular mechanism. Conclusions/interpretation: Collectively, these results highlight PCSK9 as an important regulator of CD36, PD-L1 and HLA-ABC cell surface expression in pancreatic beta cells. Data availability: RNA-seq data have been deposited to GEO database with accession number GSE182016. Mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the following identifiers: PXD027921, PXD027911 and PXD027913.

scholarly journals Flavonoids Identification and Pancreatic Beta-Cell Protective Effect of Lotus Seedpod

Antioxidants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 658 ◽  
Author(s):  
Ming-Shih Lee ◽  
Charng-Cherng Chyau ◽  
Chi-Ping Wang ◽  
Ting-Hsuan Wang ◽  
Jing-Hsien Chen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Cell Injury ◽  
Pancreatic Beta Cell ◽  
B Cell Lymphoma ◽  
Pancreatic Cell ◽  
Traditional Chinese Herbal Medicine ◽  
Lotus Seedpod

Oxidative stress is highly associated with the development of diabetes mellitus (DM), especially pancreatic beta-cell injury. Flavonoids derived from plants have caused important attention in the prevention or treatment of DM. Lotus seedpod belongs to a traditional Chinese herbal medicine and has been indicated to possess antioxidant, anti-age, anti-glycative, and hepatoprotective activities. The purpose of this study was to demonstrate the pancreatic beta-cell protective effects of lotus seedpod aqueous extracts (LSE) against oxidative injury. According to HPLC/ESI-MS-MS method, LSE was confirmed to have flavonoids derivatives, especially quercetin-3-glucuronide (Q3G). In vitro, LSE dose-dependently improved the survival and function of rat pancreatic beta-cells (RIN-m5F) from hydrogen peroxide (H2O2)-mediated loss of cell viability, impairment of insulin secretion, and promotion of oxidative stress. LSE showed potential in decreasing the H2O2-induced occurrence of apoptosis. In addition, H2O2-triggered acidic vesicular organelle formation and microtubule-associated protein light chain 3 (LC3)-II upregulation, markers of autophagy, were increased by LSE. Molecular data explored that antiapoptotic and autophagic effects of LSE, comparable to that of Q3G, might receptively be mediated via phospho-Bcl-2-associated death promoter (p-Bad)/B-cell lymphoma 2 (Bcl-2) and class III phosphatidylinositol-3 kinase (PI3K)/LC3-II signal pathway. In vivo, LSE improved the DM symptoms and pancreatic cell injury better than metformin, a drug that is routinely prescribed to treat DM. These data implied that LSE induces the autophagic signaling, leading to protect beta-cells from oxidative stress-related apoptosis and injury.

Glucose metabolism and insulin release in mouse beta HC9 cells, as model for wild-type pancreatic beta-cells

1996 ◽  
Vol 270 (5) ◽  
pp. E846-E857 ◽  
Author(s):  
Y. Liang ◽  
G. Bai ◽  
N. Doliba ◽  
C. Buettger ◽  
L. Wang ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Beta Cell ◽  
Cell Line ◽  
Insulin Release ◽  
Cell Lines ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
Glucose Sensing ◽  
Cell Functions ◽  
Glucose Phosphorylation

Glucose metabolism and its relationship with glucose-induced insulin release were studied in beta HC9 and beta TC3 cells to identify and characterize key factors controlling the intermediary metabolism of glucose and glucose-induced insulin release. The beta HC9 cell line, derived from pancreatic islets with beta-cell hyperplasia, is characterized by a normal concentration-dependency curve for glucose-stimulated insulin release, whereas the beta TC3 cell line, derived from pancreatic beta-cell tumors, shows a marked leftward shift of this curve. Maximum velocity and the Michaelis-Menten constant of glucose uptake in beta HC9 and beta TC3 cells were similar, even though GLUT-2 expression in these two cell lines differed. In both cell lines, the kinetic characteristics of glucose usage, glucose oxidation, and glucose-induced oxygen consumption were similar to those of glucose phosphorylation, indicating that the kinetics of glucose metabolism from the glucose phosphorylation step in the cytosol to the mitochondrial process of oxidative phosphorylation are determined by the glucose-phosphorylating enzyme, that is, by glucokinase in beta HC9 cells and by hexokinase in beta TC3 cells. Thus beta HC9 cells provide an opportunity for the quantitative analysis of glucose metabolism, the associated generation of coupling factors, and other essential beta-cell functions involved in glucose sensing and insulin secretion.

scholarly journals Type 1 Diabetes: Interferons and the Aftermath of Pancreatic Beta-Cell Enteroviral Infection

2020 ◽  
Vol 8 (9) ◽  
pp. 1419
Author(s):  
Pouria Akhbari ◽  
Sarah J Richardson ◽  
Noel G Morgan
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cell ◽  
Pancreatic Beta Cells ◽  
Growth Regulation ◽  
Cell Function ◽  
Viral Infections ◽  
Pancreatic Beta Cell ◽  
Enteroviral Infection ◽  
Cellular Processes

Enteroviruses (EVs) have long been implicated in the pathogenesis of type 1 diabetes (T1D), and accumulating evidence has associated virus-induced autoimmunity with the loss of pancreatic beta cells in T1D. Inflammatory cytokines including interferons (IFN) form a primary line of defence against viral infections, and their chronic elevation is a hallmark feature of many autoimmune diseases. IFNs play a key role in activating and regulating innate and adaptive immune responses, and to do so they modulate the expression of networks of genes and transcription factors known generically as IFN stimulated genes (ISGs). ISGs in turn modulate critical cellular processes ranging from cellular metabolism and growth regulation to endoplasmic reticulum (ER) stress and apoptosis. More recent studies have revealed that IFNs also modulate gene expression at an epigenetic as well as post-transcriptional and post-translational levels. As such, IFNs form a key link connecting the various genetic, environmental and immunological factors involved in the initiation and progression of T1D. Therefore, gaining an improved understanding of the mechanisms by which IFNs modulate beta cell function and survival is crucial in explaining the pathogenesis of virally-induced T1D. This should provide the means to prevent, decelerate or even reverse beta cell impairment.

scholarly journals Using FluoZin-3 and fura-2 to monitor acute accumulation of free intracellular Cd2+ in a pancreatic beta cell line

BioMetals ◽  
2019 ◽  
Vol 32 (6) ◽  
pp. 951-964 ◽  
Author(s):  
Latha M. Malaiyandi ◽  
Harsh Sharthiya ◽  
Ameir N. Barakat ◽  
Joshua R. Edwards ◽  
Kirk E. Dineley
Keyword(s):  
Beta Cell ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
The Other ◽  
Selective Detection ◽  
Fluorescent Indicators ◽  
Voltage Gated ◽  
Fura 2 ◽  
Voltage Gated Calcium Channels ◽  
Beta Cell Line

AbstractThe understanding of cellular Cd2+ accumulation and toxicity is hampered by a lack of fluorescent indicators selective for intracellular free Cd2+ ([Cd2+]i). In this study, we used depolarized MIN6 mouse pancreatic beta cells as a model for evaluating [Cd2+]i detection with commercially available fluorescent probes, most of which have been traditionally used to visualize [Ca2+]i and [Zn2+]i. We trialed a panel of 12 probes including fura-2, FluoZin-3, Leadmium Green, Rhod-5N, indo-1, Fluo-5N, and others. We found that the [Zn2+]i probe FluoZin-3 and the traditional [Ca2+]i probe fura-2 responded most consistently and robustly to [Cd2+]i accumulation mediated by voltage-gated calcium channels. While selective detection of [Cd2+]i by fura-2 required the omission of Ca2+ from extracellular buffers, FluoZin-3 responded to [Cd2+]i similarly in the presence or absence of extracellular Ca2+. Furthermore, we showed that FluoZin-3 and fura-2 can be used together for simultaneous monitoring of [Ca2+]i and [Cd2+]i in the same cells. None of the other fluorophores tested were effective [Cd2+]i detectors in this model.

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