scholarly journals The PACAP-Regulated Gene Selenoprotein T Is Abundantly Expressed in Mouse and Human β-Cells and Its Targeted Inactivation Impairs Glucose Tolerance

Endocrinology ◽  
2013 ◽  
Vol 154 (10) ◽  
pp. 3796-3806 ◽  
Author(s):  
Gaëtan Prevost ◽  
Arnaud Arabo ◽  
Long Jian ◽  
Eddy Quelennec ◽  
Dorthe Cartier ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Redox Status ◽  
Human Islets ◽  
Mutant Mice ◽  
Wild Type ◽  
Β Cells ◽  
Cellular Processes ◽  
Insulin Promoter ◽  
Selenoprotein T

Selenoproteins are involved in the regulation of redox status, which affects several cellular processes, including cell survival and homeostasis. Considerable interest has arisen recently concerning the role of selenoproteins in the regulation of glucose metabolism. Here, we found that selenoprotein T (SelT), a new thioredoxin-like protein of the endoplasmic reticulum, is present at high levels in human and mouse pancreas as revealed by immunofluorescence and quantitative PCR. Confocal immunohistochemistry studies revealed that SelT is mostly confined to insulin- and somatostatin-producing cells in mouse and human islets. To elucidate the role of SelT in β-cells, we generated, using a Cre-Lox strategy, a conditional pancreatic β-cell SelT-knockout C57BL/6J mice (SelT-insKO) in which SelT gene disruption is under the control of the rat insulin promoter Cre gene. Glucose administration revealed that male SelT-insKO mice display impaired glucose tolerance. Although insulin sensitivity was not modified in the mutant mice, the ratio of glucose to insulin was significantly higher in the SelT-insKO mice compared with wild-type littermates, pointing to a deficit in insulin production/secretion in mutant mice. In addition, morphometric analysis showed that islets from SelT-insKO mice were smaller and that their number was significantly increased compared with islets from their wild-type littermates. Finally, we found that SelT is up-regulated by pituitary adenylate cyclase-activating polypeptide (PACAP) in β-pancreatic cells and that SelT could act by facilitating a feed-forward mechanism to potentiate insulin secretion induced by the neuropeptide. Our findings are the first to show that the PACAP-regulated SelT is localized in pancreatic β- and δ-cells and is involved in the control of glucose homeostasis.

scholarly journals Role of Proinsulin Self-Association in Mutant INS gene-induced Diabetes of Youth

2019 ◽  
Author(s):  
Jinhong Sun ◽  
Yi Xiong ◽  
Xin Li ◽  
Leena Haataja ◽  
Wei Chen ◽  
...  
Keyword(s):  
Human Islets ◽  
Dominant Negative ◽  
Negative Behavior ◽  
Insulin Production ◽  
Wild Type ◽  
Negative Effects ◽  
Β Cells ◽  
Self Association ◽  
Novel Therapeutic

AbstractAbnormal interactions between misfolded mutant and wild-type (WT) proinsulin in the endoplasmic reticulum (ER) drive the molecular pathogenesis of Mutant-INS-gene induced Diabetes of Youth (MIDY). How these abnormal interactions are initiated remains unknown. Normally, proinsulin-WT dimerizes in the ER. Here, we suggest that the normal proinsulin-proinsulin contact surface, involving the B-chain, contributes to dominant-negative effects of misfolded MIDY mutants. Specifically, we find that proinsulin Tyr-B16, which is a key residue in normal proinsulin dimerization, helps confer dominant-negative behavior of MIDY mutant proinsulin-C(A7)Y. Substitutions of Tyr-B16 with ether Ala, Asp, or Pro in proinsulin-C(A7)Y each decrease the abnormal interactions between the MIDY mutant and proinsulin-WT, rescuing proinsulin-WT export, limiting ER stress, and increasing insulin production in β-cells and human islets. This study reveals the first evidence indicating that noncovalent proinsulin-proinsulin contact initiates dominant-negative behavior of misfolded proinsulin, pointing to a novel therapeutic target to enhance bystander proinsulin export for increased insulin production.

scholarly journals Combinatorial transcription factor profiles predict mature and functional human islet α and β cells

2021 ◽  
Author(s):  
Shristi Shrestha ◽  
Diane C. Saunders ◽  
John T. Walker ◽  
Joan Camunas-Soler ◽  
Xiao-Qing Dai ◽  
...  
Keyword(s):  
Islet Cells ◽  
Hormone Secretion ◽  
Developmental State ◽  
Human Islets ◽  
Glucose Sensing ◽  
Pancreatic Tissue ◽  
Β Cells ◽  
Cellular Processes ◽  
Normal Human ◽  
Multiple Donors

ABSTRACTIslet-enriched transcription factors (TFs) exert broad control over cellular processes in pancreatic α and β cells and changes in their expression are associated with developmental state and diabetes. However, the implications of heterogeneity in TF expression across islet cell populations are not well understood. To define this TF heterogeneity and its consequences for cellular function, we profiled >40,000 cells from normal human islets by scRNA-seq and stratified α and β cells based on combinatorial TF expression. Subpopulations of islet cells co-expressing ARX/MAFB (α cells) and MAFA/MAFB (β cells) exhibited greater expression of key genes related to glucose sensing and hormone secretion relative to subpopulations expressing only one or neither TF. Moreover, all subpopulations were identified in native pancreatic tissue from multiple donors. By Patch-seq, MAFA/MAFB co-expressing β cells showed enhanced electrophysiological activity. Thus, these results indicate combinatorial TF expression in islet α and β cells predicts highly functional, mature subpopulations.

scholarly journals Role of Nitric Oxide in the Pathogenesis of Encephalomyocarditis Virus-Induced Diabetes in Mice

2009 ◽  
Vol 83 (16) ◽  
pp. 8004-8011 ◽  
Author(s):  
Young-Sun Lee ◽  
Na Li ◽  
Seungjin Shin ◽  
Hee-Sook Jun
Keyword(s):  
Virus Infection ◽  
Encephalomyocarditis Virus ◽  
Wild Type ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Diabetes In Mice ◽  
Tnf Α ◽  
Deficient Mice

ABSTRACT The D variant of encephalomyocarditis virus (EMC-D virus) causes diabetes in mice by destroying pancreatic β cells. In mice infected with a low dose of EMC-D virus, macrophages play an important role in β-cell destruction by producing soluble mediators such as interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and nitric oxide (NO). To investigate the role of NO and inducible NO synthase (iNOS) in the development of diabetes in EMC-D virus-infected mice, we infected iNOS-deficient DBA/2 mice with EMC-D virus (2 × 102 PFU/mouse). Mean blood glucose levels in EMC-D virus-infected iNOS-deficient mice and wild-type mice were 205.5 and 466.7 mg/dl, respectively. Insulitis and macrophage infiltration were reduced in islets of iNOS-deficient mice compared with wild-type mice at 3 days after EMC-D virus infection. Apoptosis of β cells was decreased in iNOS-deficient mice, as evidenced by reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells. There were no differences in mRNA expression of antiapoptotic molecules Bcl-2, Bcl-xL, Bcl-w, Mcl-1, cIAP-1, and cIAP-2 between wild-type and iNOS-deficient mice, whereas expression of proapoptotic Bax and Bak mRNAs was significantly decreased in iNOS-deficient mice. Expression of IL-1β and TNF-α mRNAs was significantly decreased in both islets and macrophages of iNOS-deficient mice compared with wild-type mice after EMC-D virus infection. Nuclear factor κB was less activated in macrophages of iNOS-deficient mice after virus infection. We conclude that NO plays an important role in the activation of macrophages and apoptosis of pancreatic β cells in EMC-D virus-infected mice and that deficient iNOS gene expression inhibits macrophage activation and β-cell apoptosis, contributing to prevention of EMC-D virus-induced diabetes.

scholarly journals Enhanced Hippocampal CA1 LTP but Normal Spatial Learning in Inositol 1,4,5-trisphosphate 3-kinase(A)-Deficient Mice

1998 ◽  
Vol 5 (4) ◽  
pp. 317-330 ◽  
Author(s):  
Kisun Jun ◽  
Gildon Choi ◽  
Sung-Gu Yang ◽  
Kwan Yong Choi ◽  
Hyun Kim ◽  
...  
Keyword(s):  
Spatial Learning ◽  
Mutant Mice ◽  
Wild Type ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Morris Water Maze Task ◽  
Significant Difference ◽  
Kinase A

To define the physiological role of IP33-kinase(A) in vivo, we have generated a mouse strain with a null mutation of the IP33-kinase(A) locus by gene targeting. Homozygous mutant mice were fully viable, fertile, apparently normal, and did not show any morphological anomaly in brain sections. In the mutant brain, the IP4 level was significantly decreased whereas the IP3 level did not change, demonstrating a major role of IP33-kinase(A) in the generation of IP4. Nevertheless, no significant difference was detected in the hippocampal neuronal cells of the wild-type and the mutant mice in the kinetics of Ca2+ regulation after glutamate stimulation. Electrophysiological analyses carried out in hippocampal slices showed that the mutation significantly enhanced the LTP in the hippocampal CA1 region, but had no effect on the LTP in dentate gyrus (DG). No difference was noted, however, between the mutant and the wild-type mice in the Morris water maze task. Our results indicate that IP33-kinase(A) may play an important role in the regulation of LTP in hippocampal CA1 region through the generation of IP4, but the enhanced LTP in the hippocampal CA1 does not affect spatial learning and memory.

scholarly journals The clock gene Period1 regulates innate routine behaviour in mice

2014 ◽  
Vol 281 (1781) ◽  
pp. 20140034 ◽  
Author(s):  
Philipp Bechstein ◽  
Nils-Jörn Rehbach ◽  
Gowzekan Yuhasingham ◽  
Christoph Schürmann ◽  
Melanie Göpfert ◽  
...  
Keyword(s):  
Clock Gene ◽  
Memory Deficits ◽  
Nest Building ◽  
Partner Choice ◽  
Mutant Mice ◽  
Spatial Learning And Memory ◽  
Wild Type ◽  
Circadian Clock Gene ◽  
Deficient Mice

Laboratory mice are well capable of performing innate routine behaviour programmes necessary for courtship, nest-building and exploratory activities although housed for decades in animal facilities. We found that in mice inactivation of the clock gene Period1 profoundly changes innate routine behaviour programmes like those necessary for courtship, nest building, exploration and learning. These results in wild-type and Period1 mutant mice, together with earlier findings on courtship behaviour in wild-type and period -mutant Drosophila melanogaster , suggest a conserved role of Period- genes on innate routine behaviour. Additionally, both per -mutant flies and Period1 -mutant mice display spatial learning and memory deficits. The profound influence of Period1 on routine behaviour programmes in mice, including female partner choice, may be independent of its function as a circadian clock gene, since Period1 -deficient mice display normal circadian behaviour.

scholarly journals Endogenous Somatostatin Is Critical in Regulating the Acute Effects of l-Arginine on Growth Hormone and Insulin Release in Mice

Endocrinology ◽  
2013 ◽  
Vol 154 (7) ◽  
pp. 2393-2398 ◽  
Author(s):  
Jose Córdoba-Chacón ◽  
Manuel D. Gahete ◽  
Ana I. Pozo-Salas ◽  
Justo P. Castaño ◽  
Rhonda D. Kineman ◽  
...  
Keyword(s):  
Insulin Release ◽  
Fold Increase ◽  
Second Phase ◽  
Acute Effects ◽  
Wild Type ◽  
Β Cells ◽  
Glucose Levels ◽  
First Phase Insulin Secretion

Abstract l-arginine (l-Arg) rapidly stimulates GH and insulin release in vivo. It has been hypothesized that l-Arg stimulates GH release by lowering hypothalamic somatostatin (SST) tone. l-Arg may also act directly at the pituitary to stimulate GH release. Moreover, l-Arg has a direct stimulatory effect on β-cells, which is thought to be blunted by the release of SST from pancreatic δ-cells. To confirm the role of endogenous SST on l-Arg-induced GH and insulin release, wild-type (WT) and SST-knockout (SST-KO) mice were injected with l-Arg (ip; 0.8 g/kg), and pre-/post-injection GH, insulin, and glucose levels were measured. In WT mice, l-Arg evoked a 6-fold increase in circulating GH. However, there was only a modest increase in GH levels in WT pituitary cell cultures treated with l-Arg. In contrast, l-Arg failed to increase GH in SST-KO beyond their already elevated levels. These results further support the hypothesis that the primary mechanism by which l-Arg acutely increases GH in vivo is by lowering hypothalamic SST input to the pituitary and not via direct pituitary effects. Additionally, l-Arg induced a clear first-phase insulin secretion in WT mice, but not in SST-KO. However, SST-KO, but not WT mice, displayed a robust and sustained second-phase insulin release. These results further support a role for endogenous SST in regulating l-Arg-mediated insulin release.

scholarly journals Usp14 is required for spermatogenesis and ubiquitin stress responses in Drosophila melanogaster

2019 ◽  
Author(s):  
Levente Kovács ◽  
Ágota Nagy ◽  
Margit Pál ◽  
Peter Deák
Keyword(s):  
Male Sterility ◽  
Stress Responses ◽  
Expression Patterns ◽  
Loss Of Function ◽  
Wild Type ◽  
Cellular Processes ◽  
Protein Conjugates ◽  
Covalently Linked ◽  
Mutant Phenotypes

ABSTRACTDeubiquitinating (DUB) enzymes free covalently linked ubiquitins from ubiquitin-ubiquitin and ubiquitin-protein conjugates, and thereby maintain the equilibrium between free and conjugated ubiquitins and regulate ubiquitin-mediated cellular processes. The present genetic analyses of mutant phenotypes demonstrate that loss of Usp14 function results in male sterility, with defects in spermatid individualization and reduced testicular free monoubiquitin levels. These phenotypes were rescued by germline specific overexpression of wild type Usp14. Synergistic genetic interactions with Ubi-p63E and cycloheximide sensitivity suggest that ubiquitin shortage is a primary cause of male sterility. In addition, Usp14 is predominantly expressed in testes in Drosophila, and differential expression patterns may be causative of testis-specific loss of function Usp14 phenotypes. Collectively, these results suggest a major role of Usp14 in maintaining normal steady state free monoubiquitin levels during the later stages of Drosophila spermatogenesis.

scholarly journals A4 THE CIRCADIAN TIMING OF INFLAMMATORY BOWEL DISEASE

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 4-5
Author(s):  
Z Taleb ◽  
K Stokes ◽  
H Wang ◽  
S M Collins ◽  
W I Khan ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Circadian Clock ◽  
Bowel Disease ◽  
Mutant Mice ◽  
Intestinal Epithelial ◽  
Wild Type ◽  
Colon Tissue ◽  
Rhythmic Expression ◽  
Inflammatory Bowel

Abstract Background The circadian clock is a highly conserved molecular pacemaker found in nearly every cell of the body. It consists of the genes BMAL1 and CLOCK that positively regulate CRY and PER, their negative regulators, resulting in a transcription/translation feedback loop that has a 24 hour cycle. This core clock mechanism drives the rhythmic expression of over 40% of the genome in a tissue-specific manner and therefore imposes 24 hour rhythms on many physiological processes. Shift work, which causes disruptions to the natural 24 hour physiological rhythms, has been shown to lead to an increased incidence of inflammatory bowel disease (IBD). Aims This study aims to characterize daily rhythms in inflammation and regeneration of the colon upon induction of acute colitis. We also aim to investigate the intestinal epithelial-specific effects of circadian clock disruption on overall disease progression. We hypothesize that the absence of a functional circadian clock eliminates proliferation rhythms of intestinal epithelial cells and disrupts the rhythms of inflammatory cytokines, thereby increasing the pathogenesis of IBD. Methods We tested the role of the clock in IBD using BMAL1+/+ (wild type) and BMAL1-/- (null mutant) mice. We also investigated the effects of the circadian clock specific to intestinal epithelial tissue using Vil+/+;BMAL1flox/flox (control) and VilCre/+;BMAL1flox/flox (conditional intestinal epithelial mutant) mice. Dextran Sulfate Sodium (DSS) was applied to induce acute colitis. Results We observed significantly decreased survival of BMAL1 circadian clock mutant mice when given colitis. A histology analysis indicates increased lesioning and overall inflammation in BMAL1-/- colon tissue. Disease activity and cytokine analyses reveal time-dependent severity in inflammatory response that is worse in BMAL1-/- mice. To test the circadian rhythms in intestinal regeneration of mice with IBD, we performed a 24 hour analysis comparing epithelial cell proliferation and cell death in colon tissue. We observed rhythmic expression of phosphor-histone H3 (a mitosis marker) in wild type mice which is eliminated in the BMAL1-/- lacking a circadian clock. Cell death which was measured by caspase 3 did not exhibit any differences between genotypes. Based on these results, we conclude that the loss of clock function leads to impaired regeneration during IBD, in part due to decreased and arrhythmic cell proliferation. Preliminary results in our VilCre/+;BMAL1flox/flox conditional intestinal epithelial mutant mice indicate that some of these effects may be epithelial-specific. Conclusions Our results support a critical role of the circadian clock in inflammatory bowel disease development. These data highlight that the circadian clock affects the regenerative abilities of intestinal epithelial cells. Funding Agencies CIHRChron’s and Colitis Canada, Ontario, University of Windsor

scholarly journals Diurnal Amplitudes of Arterial Pressure and Heart Rate Are Dampened in Clock Mutant Mice and Adrenalectomized Mice

Endocrinology ◽  
2008 ◽  
Vol 149 (7) ◽  
pp. 3576-3580 ◽  
Author(s):  
Hiroyoshi Sei ◽  
Katsutaka Oishi ◽  
Sachiko Chikahisa ◽  
Kazuyoshi Kitaoka ◽  
Eiji Takeda ◽  
...  
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Clock Gene ◽  
Clock Genes ◽  
Plasma Aldosterone ◽  
Mutant Mice ◽  
Wild Type ◽  
Clock Mutant ◽  
Wild Type Control

Arterial pressure (AP), heart rate (HR), and cardiovascular diseases, including ischemic heart attack and cerebrovascular accident, show diurnal variation. Evidence that circadian-related genes contribute to cardiovascular control has been accumulated. In this study, we measured the AP and HR of Clock mutant mice on the Jcl/ICR background to determine the role of the Clock gene in cardiovascular function. Mice with mutated Clock genes had a dampened diurnal rhythm of AP and HR, compared with wild-type control mice, and this difference disappeared after adrenalectomy. The diurnal acrophase in both mean arterial pressure and HR was delayed significantly in Clock mutant mice, compared with wild-type mice, and this difference remained after adrenalectomy. Clock mutant mice had a lower concentration of plasma aldosterone, compared with wild-type mice. Our data suggest that the adrenal gland is involved in the diurnal amplitude, but not the acrophase, of AP and HR, and that the function of the Clock gene may be related to the nondipping type of AP elevation.

Improved blood glucose disposal and altered insulin secretion patterns in adenosine A1 receptor knockout mice

2012 ◽  
Vol 303 (2) ◽  
pp. E180-E190 ◽  
Author(s):  
Gary K. Yang ◽  
Bertil B. Fredholm ◽  
Timothy J. Kieffer ◽  
Yin Nam Kwok
Keyword(s):  
Glucose Tolerance ◽  
Insulin Release ◽  
Knockout Mice ◽  
The Body ◽  
Glucose Disposal ◽  
Wild Type ◽  
Β Cells ◽  
Pancreas Perfusion ◽  
Glucose Levels ◽  
Glucose Challenge

Type 2 diabetes mellitus (T2DM) is characterized by the inability of the pancreatic β-cells to secrete enough insulin to meet the demands of the body. Therefore, research of potential therapeutic approaches to treat T2DM has focused on increasing insulin output from β-cells or improving systemic sensitivity to circulating insulin. In this study, we examined the role of the A1 receptor in glucose homeostasis with the use of A1 receptor knockout mice (A1R−/−). A1R−/− mice exhibited superior glucose tolerance compared with wild-type controls. However, glucose-stimulated insulin release, insulin sensitivity, weight gain, and food intake were comparable between the two genotypes. Following a glucose challenge, plasma glucagon levels in wild-type controls decreased, but this was not observed in A1R−/− mice. In addition, pancreas perfusion with oscillatory glucose levels of 10-min intervals produced a regular pattern of pulsatile insulin release with a 10-min cycling period in wild-type controls and 5 min in A1R−/− mice. When the mice were fed a high-fat diet (HFD), both genotypes exhibited impaired glucose tolerance and insulin resistance. Increased insulin release was observed in HFD-fed mice in both genotypes, but increased glucagon release was observed only in HFD-fed A1R−/− mice. In addition, the regular patterns of insulin release following oscillatory glucose perfusion were abolished in HFD-fed mice in both genotypes. In conclusion, A1 receptors in the pancreas are involved in regulating the temporal patterns of insulin release, which could have implications in the development of glucose intolerance seen in T2DM.

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