Des-Acyl Ghrelin Fragments and Analogues Promote Survival of Pancreatic β-Cells and Human Pancreatic Islets and Prevent Diabetes in Streptozotocin-Treated Rats

2012 ◽  
Vol 55 (6) ◽  
pp. 2585-2596 ◽  
Author(s):  
Riccarda Granata ◽  
Fabio Settanni ◽  
Michel Julien ◽  
Rita Nano ◽  
Gabriele Togliatto ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Human Pancreatic Islets ◽  
Acyl Ghrelin

scholarly journals Mechanism and regulation of vitamin B2 (riboflavin) uptake by mouse and human pancreatic β-cells/islets: physiological and molecular aspects

2012 ◽  
Vol 303 (9) ◽  
pp. G1052-G1058 ◽  
Author(s):  
Abhisek Ghosal ◽  
Hamid M. Said
Keyword(s):  
Pancreatic Islets ◽  
Significant Inhibition ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Human Pancreatic Islets ◽  
Primary Mouse ◽  
Metabolic Activities ◽  
Molecular Aspects ◽  
Interfering Rna ◽  
First Time

Riboflavin (RF) is essential for the normal metabolic activities of pancreatic β-cells and provides protection against oxidative stress. Very little is known about the mechanism of RF uptake by these cells and how the process is regulated. We addressed these issues using mouse-derived pancreatic β-TC-6 cells and freshly isolated primary mouse and human pancreatic islets. Our results showed 3H-RF uptake by β-TC-6 cells is Na+ independent, cis inhibited by RF-related compounds, trans stimulated by unlabeled RF, and saturable as a function of concentration (apparent Km of 0.17 ± 0.02 μM). The latter findings suggest involvement of a carrier-mediated process. Similarly, RF uptake by primary mouse and human pancreatic islets was via carrier-mediated process. RF transporters 1, 2, and 3 (RFVT-1, -3, and -2) were all expressed in mouse and human pancreatic β-cells/islets, with RFVT-1 being the predominant transporter expressed in the mouse and RFVT-3 in the human. Specific knockdown of RFVT-1 with gene-specific small interfering RNA leads to a significant inhibition in RF uptake by β-TC-6 cells. RF uptake by β-TC-6 cells was also found to be adaptively upregulated in RF deficiency via a transcriptional mechanism(s). Also, the process appears to be under the regulation of a Ca2+/calmodulin-mediated regulatory pathway. Results of these studies demonstrate, for the first time, the involvement of a carrier-mediated process for RF uptake by mouse and human pancreatic β-cells/islets. Furthermore, the process appears to be regulated by extracellular and intracellular factors.

scholarly journals The adaptor protein APPL2 controls glucose-stimulated insulin secretion via F-actin remodeling in pancreatic β-cells

2020 ◽  
Vol 117 (45) ◽  
pp. 28307-28315
Author(s):  
Baile Wang ◽  
Huige Lin ◽  
Xiaomu Li ◽  
Wenqi Lu ◽  
Jae Bum Kim ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Adaptor Protein ◽  
Hek293 Cells ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Actin Remodeling ◽  
Actin Depolymerization ◽  
Glucose Stimulated Insulin Secretion

Filamentous actin (F-actin) cytoskeletal remodeling is critical for glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells, and its dysregulation causes type 2 diabetes. The adaptor protein APPL1 promotes first-phase GSIS by up-regulating solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein expression. However, whether APPL2 (a close homology of APPL1 with the same domain organization) plays a role in β-cell functions is unknown. Here, we show that APPL2 enhances GSIS by promoting F-actin remodeling via the small GTPase Rac1 in pancreatic β-cells. β-cell specific abrogation of APPL2 impaired GSIS, leading to glucose intolerance in mice. APPL2 deficiency largely abolished glucose-induced first- and second-phase insulin secretion in pancreatic islets. Real-time live-cell imaging and phalloidin staining revealed that APPL2 deficiency abolished glucose-induced F-actin depolymerization in pancreatic islets. Likewise, knockdown of APPL2 expression impaired glucose-stimulated F-actin depolymerization and subsequent insulin secretion in INS-1E cells, which were attributable to the impairment of Ras-related C3 botulinum toxin substrate 1 (Rac1) activation. Treatment with the F-actin depolymerization chemical compounds or overexpression of gelsolin (a F-actin remodeling protein) rescued APPL2 deficiency-induced defective GSIS. In addition, APPL2 interacted with Rac GTPase activating protein 1 (RacGAP1) in a glucose-dependent manner via the bin/amphiphysin/rvs-pleckstrin homology (BAR-PH) domain of APPL2 in INS-1E cells and HEK293 cells. Concomitant knockdown of RacGAP1 expression reverted APPL2 deficiency-induced defective GSIS, F-actin remodeling, and Rac1 activation in INS-1E cells. Our data indicate that APPL2 interacts with RacGAP1 and suppresses its negative action on Rac1 activity and F-actin depolymerization thereby enhancing GSIS in pancreatic β-cells.

Tetracaine stimulates insulin secretion through the mobilization of Ca2+ from thapsigargin- and IP3-insensitive Ca2+ reservoir in pancreatic β-cells

2000 ◽  
Vol 78 (6) ◽  
pp. 462-468 ◽  
Author(s):  
José Roberto Bosqueiro ◽  
Everardo Magalhães Carneiro ◽  
Silvana Bordin ◽  
Antonio Carlos Boschero
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Isolated Islets ◽  
Inositol Triphosphate ◽  
Free Medium ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Isolated Pancreatic Islets ◽  
High Concentrations

The effect of tetracaine on 45Ca efflux, cytoplasmic Ca2+ concentration [Ca2+]i, and insulin secretion in isolated pancreatic islets and β-cells was studied. In the absence of external Ca2+, tetracaine (0.1-2.0 mM) increased the 45Ca efflux from isolated islets in a dose-dependant manner. Tetracaine did not affect the increase in 45Ca efflux caused by 50 mM K+ or by the association of carbachol (0.2 mM) and 50 mM K+. Tetracaine permanently increased the [Ca2+]i in isolated β-cells in Ca2+-free medium enriched with 2.8 mM glucose and 25 µM D-600 (methoxiverapamil). This effect was also observed in the presence of 10 mM caffeine or 1 µM thapsigargin. In the presence of 16.7 mM glucose, tetracaine transiently increased the insulin secretion from islets perfused in the absence and presence of external Ca2+. These data indicate that tetracaine mobilises Ca2+ from a thapsigargin-insensitive store and stimulates insulin secretion in the absence of extracellular Ca2+. The increase in 45Ca efflux caused by high concentrations of K+ and by carbachol indicates that tetracaine did not interfere with a cation or inositol triphosphate sensitive Ca2+ pool in β-cells.

scholarly journals Palmitate Activates Autophagy in INS-1E β-Cells and in Isolated Rat and Human Pancreatic Islets

PLoS ONE ◽  
2012 ◽  
Vol 7 (5) ◽  
pp. e36188 ◽  
Author(s):  
Luisa Martino ◽  
Matilde Masini ◽  
Michela Novelli ◽  
Pascale Beffy ◽  
Marco Bugliani ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Β Cells ◽  
Human Pancreatic Islets ◽  
Isolated Rat

Bach1 deficiency protects pancreatic β-cells from oxidative stress injury

2013 ◽  
Vol 305 (5) ◽  
pp. E641-E648 ◽  
Author(s):  
Keiichi Kondo ◽  
Yasushi Ishigaki ◽  
Junhong Gao ◽  
Tetsuya Yamada ◽  
Junta Imai ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Pancreatic Islets ◽  
Antioxidative Enzymes ◽  
Heme Oxygenase 1 ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Stress Injury ◽  
Induced Apoptosis ◽  
Deficient Mice

BTB and CNC homology 1 (Bach1) is a transcriptional repressor of antioxidative enzymes, such as heme oxygenase-1 (HO-1). Oxidative stress is reportedly involved in insulin secretion impairment and obesity-associated insulin resistance. However, the role of Bach1 in the development of diabetes is unclear. HO-1 expression in the liver, white adipose tissue, and pancreatic islets was markedly upregulated in Bach1-deficient mice. Unexpectedly, glucose and insulin tolerance tests showed no differences in obese wild-type (WT) and obese Bach1-deficient mice after high-fat diet loading for 6 wk, suggesting minimal roles of Bach1 in the development of insulin resistance. In contrast, Bach1 deficiency significantly suppressed alloxan-induced pancreatic insulin content reduction and the resultant glucose elevation. Furthermore, TUNEL-positive cells in pancreatic islets of Bach1-deficient mice were markedly decreased, by 60%, compared with those in WT mice. HO-1 expression in islets was significantly upregulated in alloxan-injected Bach1-deficient mice, whereas expression of other antioxidative enzymes, e.g., catalase, superoxide dismutase, and glutathione peroxidase, was not changed by either alloxan administration or Bach1 deficiency. Our results suggest that Bach1 deficiency protects pancreatic β-cells from oxidative stress-induced apoptosis and that the enhancement of HO-1 expression plays an important role in this protection.

scholarly journals Identification of a novel lncRNA (G3R1) regulated by GLIS3 in pancreatic β-cells

2020 ◽  
Vol 65 (3) ◽  
pp. 59-67
Author(s):  
David W Scoville ◽  
Artiom Gruzdev ◽  
Anton M Jetten
Keyword(s):  
Pancreatic Islets ◽  
Knockout Mouse ◽  
Cell Function ◽  
Significant Loss ◽  
Messenger Rnas ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Phenotypic Analysis ◽  
Cell Functions

Recent advances in high throughput RNA sequencing have revealed that, in addition to messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs) play an important role in the regulation of many cell functions and of organ development. While a number of lncRNAs have been identified in pancreatic islets, their function remains largely undetermined. Here, we identify a novel long ncRNA regulated by the transcription factor GLIS3, which we refer to as GLIS3 regulated 1 (G3R1). This lncRNA was identified for its significant loss of expression in GLIS3 knockout mouse pancreatic islets. G3R1 appears to be specifically expressed in mouse pancreatic β-cells and in a β-cell line (βTC-6). ChIP-seq analysis indicated that GLIS3 and other islet-enriched transcription factors bind near the G3R1 gene, suggesting they directly regulate G3R1 transcription. Similarly, an apparent human homolog of G3R1 displays a similar expression pattern, with additional expression seen in human brain. In order to determine the function of G3R1 in mouse pancreatic β-cells, we utilized CRISPR to develop a knockout mouse where ~80% of G3R1 sequence is deleted. Phenotypic analysis of these mice did not reveal any impairment in β-cell function or glucose regulation, indicating the complexity underlying the study of lncRNA function.

scholarly journals Bionic Organs: Shear Forces Reduce Pancreatic Islet and Mammalian Cell Viability during the Process of 3D Bioprinting

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 304
Author(s):  
Marta Klak ◽  
Patrycja Kowalska ◽  
Tomasz Dobrzański ◽  
Grzegorz Tymicki ◽  
Piotr Cywoniuk ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Culture Medium ◽  
Control Group ◽  
3D Bioprinting ◽  
Β Cells ◽  
Carrier Solution ◽  
Human Pancreatic Islets ◽  
Cell Carrier ◽  
Inner Diameter ◽  
Extrusion Method

Background: 3D bioprinting is the future of constructing functional organs. Creating a bioactive scaffold with pancreatic islets presents many challenges. The aim of this paper is to assess how the 3D bioprinting process affects islet viability. Methods: The BioX 3D printer (Cellink), 600 μm inner diameter nozzles, and 3% (w/v) alginate cell carrier solution were used with rat, porcine, and human pancreatic islets. Islets were divided into a control group (culture medium) and 6 experimental groups (each subjected to specific pressure between 15 and 100 kPa). FDA/PI staining was performed to assess the viability of islets. Analogous studies were carried out on α-cells, β-cells, fibroblasts, and endothelial cells. Results: Viability of human pancreatic islets was as follows: 92% for alginate-based control and 94%, 90%, 74%, 48%, 61%, and 59% for 15, 25, 30, 50, 75, and 100 kPa, respectively. Statistically significant differences were observed between control and 50, 75, and 100 kPa, respectively. Similar observations were made for porcine and rat islets. Conclusions: Optimal pressure during 3D bioprinting with pancreatic islets by the extrusion method should be lower than 30 kPa while using 3% (w/v) alginate as a carrier.

scholarly journals SARS-CoV-2 receptor Angiotensin I-Converting Enzyme type 2 (ACE2) is expressed in human pancreatic β-cells and in the human pancreas microvasculature

2020 ◽  
Author(s):  
Daniela Fignani ◽  
Giada Licata ◽  
Noemi Brusco ◽  
Laura Nigi ◽  
Giuseppina E. Grieco ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Human Pancreas ◽  
Converting Enzyme ◽  
Angiotensin I ◽  
Β Cells ◽  
Β Cell ◽  
Human Pancreatic Islets ◽  
Ductal Cells ◽  
Angiotensin I Converting Enzyme

AbstractIncreasing evidence demonstrated that the expression of Angiotensin I-Converting Enzyme type 2 (ACE2), is a necessary step for SARS-CoV-2 infection permissiveness. In the light of the recent data highlighting an association between COVID-19 and diabetes, a detailed analysis aimed at evaluating ACE2 expression pattern distribution in human pancreas is still lacking. Here, we took advantage of INNODIA network EUnPOD biobank collection to thoroughly analyse ACE2, both at mRNA and protein level, in multiple human pancreatic tissues and using several methodologies.Using multiple reagents and antibodies, we showed that ACE2 is expressed in human pancreatic islets, where it is preferentially expressed in subsets of insulin producing β-cells. ACE2 is also is highly expressed in pancreas microvasculature pericytes and moderately expressed in rare scattered ductal cells. By using different ACE2 antibodies we showed that a recently described short-ACE2 isoform is also prevalently expressed in human β-cells.Finally, using RT-qPCR, RNA-seq and High-Content imaging screening analysis, we demonstrated that pro-inflammatory cytokines, but not palmitate, increases ACE2 expression in the β-cell line EndoC-βH1 and in primary human pancreatic islets.Taken together, our data indicate a potential link between SARS-CoV-2 and diabetes through putative infection of pancreatic microvasculature and/or ductal cells and/or through direct β-cell virus tropism.

Sign in / Sign up

Export Citation Format

Share Document