scholarly journals Suppression of the Nuclear Factor Eny2 Increases Insulin Secretion in Poorly Functioning INS-1E Insulinoma Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
P. Dames ◽  
M. Weise ◽  
R. Puff ◽  
B. Göke ◽  
K. G. Parhofer ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Glucose Sensing ◽  
Metabolic Adaptation ◽  
Nuclear Factor ◽  
Experimental Conditions ◽  
Mouse Pancreatic Islets ◽  
Potential Link ◽  
Insulinoma Cells

Eny2, the mammalian ortholog of yeast Sus1 and drosophila E(y)2, is a nuclear factor that participates in several steps of gene transcription and in mRNA export. We had previously found that Eny2 expression changes in mouse pancreatic islets during the metabolic adaptation to pregnancy. We therefore hypothesized that the protein contributes to the regulation of islet endocrine cell function and tested this hypothesis in rat INS-1E insulinoma cells. Overexpression of Eny2 had no effect but siRNA-mediated knockdown of Eny2 resulted in markedly increased glucose and exendin-4-induced insulin secretion from otherwise poorly glucose-responsive INS-1E cells. Insulin content, cellular viability, and the expression levels of several key components of glucose sensing remained unchanged; however glucose-dependent cellular metabolism was higher after Eny2 knockdown. Suppression of Eny2 enhanced the intracellular incretin signal downstream of cAMP. The use of specific cAMP analogues and pathway inhibitors primarily implicated the PKA and to a lesser extent the EPAC pathway. In summary, we identified a potential link between the nuclear protein Eny2 and insulin secretion. Suppression of Eny2 resulted in increased glucose and incretin-induced insulin release from a poorly glucose-responsive INS-1E subline. Whether these findings extend to other experimental conditions or to in vivo physiology needs to be determined in further studies.

scholarly journals PINK1 deficiency in β-cells increases basal insulin secretion and improves glucose tolerance in mice

Open Biology ◽  
2014 ◽  
Vol 4 (5) ◽  
pp. 140051 ◽  
Author(s):  
Emma Deas ◽  
Kaisa Piipari ◽  
Asif Machhada ◽  
Abi Li ◽  
Ana Gutierrez-del-Arroyo ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Cell Function ◽  
Glucose Sensing ◽  
Β Cells ◽  
Β Cell Function ◽  
Basal Insulin Secretion ◽  
Low Glucose ◽  
Induced Apoptosis

The Parkinson's disease (PD) gene, PARK6 , encodes the PTEN-induced putative kinase 1 (PINK1) mitochondrial kinase, which provides protection against oxidative stress-induced apoptosis. Given the link between glucose metabolism, mitochondrial function and insulin secretion in β-cells, and the reported association of PD with type 2 diabetes, we investigated the response of PINK1-deficient β-cells to glucose stimuli to determine whether loss of PINK1 affected their function. We find that loss of PINK1 significantly impairs the ability of mouse pancreatic β-cells (MIN6 cells) and primary intact islets to take up glucose. This was accompanied by higher basal levels of intracellular calcium leading to increased basal levels of insulin secretion under low glucose conditions. Finally, we investigated the effect of PINK1 deficiency in vivo and find that PINK1 knockout mice have improved glucose tolerance. For the first time, these combined results demonstrate that loss of PINK1 function appears to disrupt glucose-sensing leading to enhanced insulin release, which is uncoupled from glucose uptake, and suggest a key role for PINK1 in β-cell function.

scholarly journals The Loss of ARNT/HIF1β in Male Pancreatic β-Cells Is Protective Against High-Fat Diet–Induced Diabetes

Endocrinology ◽  
2019 ◽  
Vol 160 (12) ◽  
pp. 2825-2836 ◽  
Author(s):  
Monica Hoang ◽  
Sabina Paglialunga ◽  
Eric Bombardier ◽  
A Russell Tupling ◽  
Jamie W Joseph
Keyword(s):  
Insulin Secretion ◽  
High Fat Diet ◽  
Cell Function ◽  
Glucose Sensing ◽  
Lipid Signaling ◽  
High Fat ◽  
Β Cells ◽  
Β Cell

Abstract The transcription factor aryl hydrocarbon receptor nuclear translocator (ARNT)/hypoxia-inducible factor (HIF)-1β (ARNT/HIF1β) plays a key role in maintaining β-cell function and has been shown to be one of the most downregulated transcription factors in islets from patients with type 2 diabetes. We have shown a role for ARNT/HIF1β in glucose sensing and insulin secretion in vitro and no defects in in vivo glucose homeostasis. To gain a better understanding of the role of ARNT/HIF1β in the development of diabetes, we placed control (+/+/Cre) and β-cell–specific ARNT/HIF1β knockout (fl/fl/Cre) mice on a high-fat diet (HFD). Unlike the control (+/+/Cre) mice, HFD-fed fl/fl/Cre mice had no impairment in in vivo glucose tolerance. The lack of impairment in HFD-fed fl/fl/Cre mice was partly due to an improved islet glucose-stimulated NADPH/NADP+ ratio and glucose-stimulated insulin secretion. The effects of the HFD-rescued insulin secretion in fl/fl/Cre islets could be reproduced by treating low-fat diet (LFD)–fed fl/fl/Cre islets with the lipid signaling molecule 1-monoacylglcyerol. This suggests that the defects seen in LFD-fed fl/fl/Cre islet insulin secretion involve lipid signaling molecules. Overall, mice lacking ARNT/HIF1β in β-cells have altered lipid signaling in vivo and are resistant to an HFD’s ability to induce diabetes.

scholarly journals Follow-up of GK rats during prediabetes highlights increased insulin action and fat deposition despite low insulin secretion

2008 ◽  
Vol 294 (1) ◽  
pp. E168-E175 ◽  
Author(s):  
Jamileh Movassat ◽  
Danièle Bailbé ◽  
Cécile Lubrano-Berthelier ◽  
Françoise Picarel-Blanchot ◽  
Eric Bertin ◽  
...  
Keyword(s):  
Body Composition ◽  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Cell Function ◽  
Cell Mass ◽  
The Body ◽  
Whole Body ◽  
Β Cell ◽  
Gk Rats

The adult Goto-Kakizaki (GK) rat is characterized by impaired glucose-induced insulin secretion in vivo and in vitro, decreased β-cell mass, decreased insulin sensitivity in the liver, and moderate insulin resistance in muscles and adipose tissue. GK rats do not exhibit basal hyperglycemia during the first 3 wk after birth and therefore could be considered prediabetic during this period. Our aim was to identify the initial pathophysiological changes occurring during the prediabetes period in this model of type 2 diabetes (T2DM). To address this, we investigated β-cell function, insulin sensitivity, and body composition in normoglycemic prediabetic GK rats. Our results revealed that the in vivo secretory response of GK β-cells to glucose is markedly reduced and the whole body insulin sensitivity is increased in the prediabetic GK rats in vivo. Moreover, the body composition of suckling GK rats is altered compared with age-matched Wistar rats, with an increase of the number of adipocytes before weaning despite a decreased body weight and lean mass in the GK rats. None of these changes appeared to be due to the postnatal nutritional environment of GK pups as demonstrated by cross-fostering GK pups with nondiabetic Wistar dams. In conclusion, in the GK model of T2DM, β-cell dysfunction associated with increased insulin sensitivity and the alteration of body composition are proximal events that might contribute to the establishment of overt diabetes in adult GK rats.

scholarly journals A Systematic Review of Beta Cell Function in Adults of Black African Ethnicity

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
M. Ladwa ◽  
O. Hakim ◽  
S. A. Amiel ◽  
L. M. Goff
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Beta Cell ◽  
Beta Cell Function ◽  
Cell Function ◽  
Normal Glucose Tolerance ◽  
Qualitative Synthesis ◽  
Intravenous Glucose ◽  
Black African

Background. Understanding ethnic differences in beta cell function has important implications for preventative and therapeutic strategies in populations at high risk of type 2 diabetes (T2D). The existing literature, largely drawn from work in children and adolescents, suggests that beta cell function in black African (BA) populations is upregulated when compared to white Europeans (WE). Methods. A systematic literature search was undertaken in June 2018 to identify comparative studies of beta cell function between adults (>age 18 years) of indigenous/diasporic BA and WE ethnicity. All categories of glucose tolerance and all methodologies of assessing beta cell function in vivo were included. Results. 41 studies were identified for inclusion into a qualitative synthesis. The majority were studies in African American populations (n=30) with normal glucose tolerance (NGT)/nondiabetes (n=25), using intravenous glucose stimulation techniques (n=27). There were fewer studies in populations defined as only impaired fasting glucose/impaired glucose tolerance (IFG/IGT) (n=3) or only T2D (n=3). Although BA broadly exhibited greater peripheral insulin responses than WE, the relatively small number of studies which measured C-peptide to differentiate between beta cell insulin secretion and hepatic insulin extraction (n=14) had highly variable findings. In exclusively IGT or T2D cohorts, beta cell insulin secretion was found to be lower in BA compared to WE. Conclusions. There is inconsistent evidence for upregulated beta cell function in BA adults, and they may in fact exhibit greater deficits in insulin secretory function as glucose intolerance develops.

Effect of gestational hyperglycemia on insulin secretion in vivo and in vitro by fetal rat pancreas

1986 ◽  
Vol 251 (1) ◽  
pp. E86-E91 ◽  
Author(s):  
M. T. Bihoreau ◽  
A. Ktorza ◽  
A. Kervran ◽  
L. Picon
Keyword(s):  
Insulin Secretion ◽  
B Cell ◽  
Insulin Release ◽  
Plasma Insulin ◽  
Cell Function ◽  
Pregnant Rats ◽  
Fetal Rat ◽  
Gestational Hyperglycemia

The effects of gestational hyperglycemia on B-cell function were studied in near-term fetuses from unrestrained pregnant rats made slightly or highly hyperglycemic using continuous glucose infusion during the last week of pregnancy. Pancreatic and plasma insulin and insulin secretion in vitro were studied in the fetuses. Compared with controls, slightly hyperglycemic fetuses showed increased pancreatic and plasma insulin concentrations and similar insulin release in response to glucose in vitro. In highly hyperglycemic fetuses, pancreatic and plasma insulin concentrations were unchanged compared with controls, and insulin release in vitro was insensitive to glucose and to the mixture glucose plus theophylline. These results confirm that glucose is able to stimulate insulin secretion in normal or slightly hyperglycemic fetuses and suggest that severe hyperglycemia per se, without association of other metabolic disorders or toxic injuries, profoundly alters the stimulus-secretion coupling of the fetal rat B-cell.

scholarly journals Antigen recognition. V. Requirement for histocompatibility between antigen-presenting cell and B cell in the response to a thymus-dependent antigen, and lack of allogeneic restriction between T and B cells.

1981 ◽  
Vol 154 (3) ◽  
pp. 676-687 ◽  
Author(s):  
E Nisbet-Brown ◽  
B Singh ◽  
E Diener
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Function ◽  
Fetal Liver ◽  
T And B Cells ◽  
Antigen Presenting Cell ◽  
Experimental Conditions ◽  
Left Hand ◽  
Antigen Presenting

The restrictions imposed by the major histocompatibility complex on T-B-antigen-presenting cell (APC) interactions were studied with an in vivo adoptive transfer system, using mutually tolerant T and B cells taken from one-way fetal liver chimeras. It was found that the B cells and adoptive recipient (which provides APC function) have to share determinants encoded by the left-hand end of the H-2 complex for cooperation, whereas there is apparently no such requirement for T-B cell syngeneicity. Suppression arising from allogeneic effects between the host and the transferred T or B cells was excluded by the use of tolerant as well as normal adoptive recipients; both were functionally equivalent. We conclude that under experimental conditions, unrestricted helper T cell function and concurrent APC-B cell genetic restriction can be demonstrated in vivo.

scholarly journals Nuclear factor κB–inducing kinase activation as a mechanism of pancreatic β cell failure in obesity

2015 ◽  
Vol 212 (8) ◽  
pp. 1239-1254 ◽  
Author(s):  
Elisabeth K. Malle ◽  
Nathan W. Zammit ◽  
Stacey N. Walters ◽  
Yen Chin Koay ◽  
Jianmin Wu ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Association Studies ◽  
Nuclear Factor Κb ◽  
Negative Regulator ◽  
Genome Wide Association Studies ◽  
Nuclear Factor ◽  
Pancreatic Β Cell ◽  
Β Cell ◽  
The Metabolic Syndrome

The nuclear factor κB (NF-κB) pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic β cell dysfunction in the metabolic syndrome. Whereas canonical NF-κB signaling is well studied, there is little information on the divergent noncanonical NF-κB pathway in the context of pancreatic islet dysfunction. Here, we demonstrate that pharmacological activation of the noncanonical NF-κB–inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. We identify NIK as a critical negative regulator of β cell function, as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of noncanonical NF-κB components p100 to p52, and accumulation of RelB. TNF and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive β cell–intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the noncanonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to β cell failure. These studies reveal that NIK contributes a central mechanism for β cell failure in diet-induced obesity.

scholarly journals Combined Deficiency of p50 and cRel in CD4+ T Cells Reveals an Essential Requirement for Nuclear Factor κB in Regulating Mature T Cell Survival and In Vivo Function

2003 ◽  
Vol 197 (7) ◽  
pp. 861-874 ◽  
Author(s):  
Ye Zheng ◽  
Monika Vig ◽  
Jesse Lyons ◽  
Luk Van Parijs ◽  
Amer A. Beg
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
Cd4 T Cells ◽  
Cell Function ◽  
Nuclear Factor ◽  
T Cell Function ◽  
T Cell Survival

Signaling pathways involved in regulating T cell proliferation and survival are not well understood. Here we have investigated a possible role of the nuclear factor (NF)-κB pathway in regulating mature T cell function by using CD4+ T cells from p50−/− cRel−/− mice, which exhibit virtually no inducible κB site binding activity. Studies with these mice indicate an essential role of T cell receptor (TCR)-induced NF-κB in regulating interleukin (IL)-2 expression, cell cycle entry, and survival of T cells. Our results further indicate that NF-κB regulates TCR-induced expression of antiapoptotic Bcl-2 family members. Strikingly, retroviral transduction of CD4+ T cells with the NF-κB–inducing IκB kinase β showed that NF-κB activation is not only necessary but also sufficient for T cell survival. In contrast, our results indicate a lack of involvement of NF-κB in both IL-2 and Akt-induced survival pathways. In vivo, p50−/− cRel−/− mice showed impaired superantigen-induced T cell responses as well as decreased numbers of effector/memory and regulatory CD4+ T cells. These findings provide the first demonstration of a role for NF-κB proteins in regulating T cell function in vivo and establish a critically important function of NF-κB in TCR-induced regulation of survival.

scholarly journals Anti-Inflammatory and Antinociceptive Activities of Anthraquinone-2-Carboxylic Acid

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Jae Gwang Park ◽  
Seung Cheol Kim ◽  
Yun Hwan Kim ◽  
Woo Seok Yang ◽  
Yong Kim ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Molecular Mechanisms ◽  
Interleukin 1 ◽  
Nuclear Factor ◽  
Experimental Conditions ◽  
Gene Assay ◽  
Anti Inflammatory ◽  
Gastric Irritation

Anthraquinone compounds are one of the abundant polyphenols found in fruits, vegetables, and herbs. However, thein vivoanti-inflammatory activity and molecular mechanisms of anthraquinones have not been fully elucidated. We investigated the activity of anthraquinones using acute inflammatory and nociceptive experimental conditions. Anthraquinone-2-carboxylic acid (9,10-dihydro-9,10-dioxo-2-anthracenecarboxylic acid, AQCA), one of the major anthraquinones identified from Brazilian taheebo, ameliorated various inflammatory and algesic symptoms in EtOH/HCl- and acetylsalicylic acid- (ASA-) induced gastritis, arachidonic acid-induced edema, and acetic acid-induced abdominal writhing without displaying toxic profiles in body and organ weight, gastric irritation, or serum parameters. In addition, AQCA suppressed the expression of inflammatory genes such as cyclooxygenase- (COX-) 2 in stomach tissues and lipopolysaccharide- (LPS-) treated RAW264.7 cells. According to reporter gene assay and immunoblotting analyses, AQCA inhibited activation of the nuclear factor- (NF-)κB and activator protein- (AP-) 1 pathways by suppression of upstream signaling involving interleukin-1 receptor-associated kinase 4 (IRAK1), p38, Src, and spleen tyrosine kinase (Syk). Our data strongly suggest that anthraquinones such as AQCA act as potent anti-inflammatory and antinociceptive componentsin vivo, thus contributing to the immune regulatory role of fruits and herbs.

scholarly journals The Acute Effects of Low-Dose TNF-αon Glucose Metabolism andβ-Cell Function in Humans

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Tobias Ibfelt ◽  
Christian P. Fischer ◽  
Peter Plomgaard ◽  
Gerrit van Hall ◽  
Bente Klarlund Pedersen
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Low Dose ◽  
Cell Function ◽  
Low Grade ◽  
Intravenous Glucose ◽  
Insulin Levels ◽  
Basal Period

Type 2 diabetes is characterized by increased insulin resistance and impaired insulin secretion. Type 2 diabetes is also associated with low-grade inflammation and increased levels of proinflammatory cytokines such as TNF-α. TNF-αhas been shown to impair peripheral insulin signalingin vitroandin vivo. However, it is unclear whether TNF-αmay also affect endogenous glucose production (EGP) during fasting and glucose-stimulated insulin secretion (GSIS)in vivo. We hypothesized that low-dose TNF-αwould increase EGP and attenuate GSIS. Recombinant human TNF-αor placebo was infused in healthy, nondiabetic young men (n=10) during a 4-hour basal period followed by an intravenous glucose tolerance test (IVGTT). TNF-αlowered insulin levels by 12% during the basal period (P<0.05). In response to the IVGTT, insulin levels increased markedly in both trials, but there was no difference between trials. Compared to placebo, TNF-αdid not affect EGP during the basal period. Our results indicate that TNF-αacutely lowers basal plasma insulin levels but does not impair GSIS. The mechanisms behind this are unknown but we suggest that it may be due to TNF-αincreasing clearance of insulin from plasma without impairing beta-cell function or hepatic insulin sensitivity.

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