A novel standardized in vitro islet model system for efficacy and toxicity testing in pancreatic β-cells

2016 ◽  
Vol 258 ◽  
pp. S158
Author(s):  
B. Yesildag ◽  
A. Neelakandhan ◽  
S. Messner ◽  
W. Moritz
Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 128
Author(s):  
Yaser Albadr ◽  
Andrew Crowe ◽  
Rima Caccetta

The prevalence of type 2 diabetes mellitus is rising globally and this disease is proposed to be the next pandemic after COVID-19. Although the cause of type 2 diabetes mellitus is unknown, it is believed to involve a complex array of genetic defects that affect metabolic pathways which eventually lead to hyperglycaemia. This hyperglycaemia arises from an inability of the insulin-sensitive cells to sufficiently respond to the secreted insulin, which eventually results in the inadequate secretion of insulin from pancreatic β-cells. Several treatments, utilising a variety of mechanisms, are available for type 2 diabetes mellitus. However, more medications are needed to assist with the optimal management of the different stages of the disease in patients of varying ages with the diverse combinations of other medications co-administered. Throughout modern history, some lead constituents from ancient medicinal plants have been investigated extensively and helped in developing synthetic antidiabetic drugs, such as metformin. Teucrium polium L. (Tp) is a herb that has a folk reputation for its antidiabetic potential. Previous studies indicate that Tp extracts significantly decrease blood glucose levels r and induce insulin secretion from pancreatic β-cells in vitro. Nonetheless, the constituent/s responsible for this action have not yet been elucidated. The effects appear to be, at least in part, attributable to the presence of selected flavonoids (apigenin, quercetin, and rutin). This review aims to examine the reported glucose-lowering effect of the herb, with a keen focus on insulin secretion, specifically related to type 2 diabetes mellitus. An analysis of the contribution of the key constituent flavonoids of Tp extracts will also be discussed.


2019 ◽  
Vol 9 ◽  
Author(s):  
Rashmi Rajappa ◽  
Dornadula Sireesh ◽  
Magesh B. Salai ◽  
Kunka M. Ramkumar ◽  
Suryanarayanan Sarvajayakesavulu ◽  
...  

2020 ◽  
Vol 21 (13) ◽  
pp. 4668
Author(s):  
Rebecca Scheuer ◽  
Stephan Ernst Philipp ◽  
Alexander Becker ◽  
Lisa Nalbach ◽  
Emmanuel Ampofo ◽  
...  

The regulation of insulin biosynthesis and secretion in pancreatic β-cells is essential for glucose homeostasis in humans. Previous findings point to the highly conserved, ubiquitously expressed serine/threonine kinase CK2 as having a negative regulatory impact on this regulation. In the cell culture model of rat pancreatic β-cells INS-1, insulin secretion is enhanced after CK2 inhibition. This enhancement is preceded by a rise in the cytosolic Ca2+ concentration. Here, we identified the serine residues S2362 and S2364 of the voltage-dependent calcium channel CaV2.1 as targets of CK2 phosphorylation. Furthermore, co-immunoprecipitation experiments revealed that CaV2.1 binds to CK2 in vitro and in vivo. CaV2.1 knockdown experiments showed that the increase in the intracellular Ca2+ concentration, followed by an enhanced insulin secretion upon CK2 inhibition, is due to a Ca2+ influx through CaV2.1 channels. In summary, our results point to a modulating role of CK2 in the CaV2.1-mediated exocytosis of insulin.


2010 ◽  
Vol 1 (6) ◽  
pp. 242-251 ◽  
Author(s):  
Kohtaro Minami ◽  
Kazumasa Miyawaki ◽  
Manami Hara ◽  
Shuichi Yamada ◽  
Susumu Seino
Keyword(s):  
Β Cells ◽  

2017 ◽  
Vol 448 ◽  
pp. 108-121 ◽  
Author(s):  
Lukas A. Berchtold ◽  
Michela Miani ◽  
Thi A. Diep ◽  
Andreas N. Madsen ◽  
Valentina Cigliola ◽  
...  

Cell ◽  
2014 ◽  
Vol 159 (2) ◽  
pp. 428-439 ◽  
Author(s):  
Felicia W. Pagliuca ◽  
Jeffrey R. Millman ◽  
Mads Gürtler ◽  
Michael Segel ◽  
Alana Van Dervort ◽  
...  
Keyword(s):  
Β Cells ◽  

Endocrinology ◽  
2010 ◽  
Vol 151 (10) ◽  
pp. 4688-4695 ◽  
Author(s):  
Ye Zhang ◽  
Zhifang Xie ◽  
Guangdi Zhou ◽  
Hai Zhang ◽  
Jian Lu ◽  
...  

Pancreatic β-cells can precisely sense glucose stimulation and accordingly adjust their insulin secretion. Fructose-1,6-bisphosphatase (FBPase) is a gluconeogenic enzyme, but its physiological significance in β-cells is not established. Here we determined its physiological role in regulating glucose sensing and insulin secretion of β-cells. Considerable FBPase mRNA was detected in normal mouse islets and β-cell lines, although their protein levels appeared to be quite low. Down-regulation of FBP1 in MIN6 cells by small interfering RNA could enhance the glucose-stimulated insulin secretion (GSIS), whereas FBP1-overexpressing MIN6 cells exhibited decreased GSIS. Inhibition of FBPase activity in islet β-cells by its specific inhibitor MB05032 led to significant increase of their glucose utilization and cellular ATP to ADP ratios and consequently enhanced GSIS in vitro. Pretreatment of mice with the MB05032 prodrug MB06322 could potentiate GSIS in vivo and improve their glucose tolerance. Therefore, FBPase plays an important role in regulating glucose sensing and insulin secretion of β-cells and serves a promising target for diabetes treatment.


2009 ◽  
Vol 296 (2) ◽  
pp. C306-C316 ◽  
Author(s):  
Omar M. Faruque ◽  
Dung Le-Nguyen ◽  
Anne-Dominique Lajoix ◽  
Eric Vives ◽  
Pierre Petit ◽  
...  

Stimulation of numerous G protein-coupled receptors leads to the elevation of intracellular concentrations of cAMP, which subsequently activates the PKA pathway. Specificity of the PKA signaling module is determined by a sophisticated subcellular targeting network that directs the spatiotemporal activation of the kinase. This specific compartmentalization mechanism occurs through high-affinity interactions of PKA with A-kinase anchoring proteins (AKAPs), the role of which is to target the kinase to discrete subcellular microdomains. Recently, a peptide designated “AKAPis” has been proposed to competitively inhibit PKA-AKAP interactions in vitro. We therefore sought to characterize a cell-permeable construct of the AKAPis inhibitor and use it as a tool to characterize the impact of PKA compartmentalization by AKAPs. Using insulin-secreting pancreatic β-cells (INS-1 cells), we showed that TAT-AKAPis (at a micromolar range) dose dependently disrupted a significant fraction of endogenous PKA-AKAP interactions. Immunoflurescent analysis also indicated that TAT-AKAPis significantly affected PKA subcellular localization. Furthermore, TAT-AKAPis markedly attenuated glucagon-induced phosphorylations of p44/p42 MAPKs and cAMP response element binding protein, which are downstream effectors of PKA. In parallel, TAT-AKAPis dose dependently inhibited the glucagon-induced potentiation of insulin release. Therefore, AKAP-mediated subcellular compartmentalization of PKA represents a key mechanism for PKA-dependent phosphorylation events and potentiation of insulin secretion in intact pancreatic β-cells. More interestingly, our data highlight the effectiveness of the cell-permeable peptide-mediated approach to monitoring in cellulo PKA-AKAP interactions and delineating PKA-dependent phosphorylation events underlying specific cellular responses.


2010 ◽  
Vol 38 (1) ◽  
pp. 205-208 ◽  
Author(s):  
Angela McDonald ◽  
Sarah Fogarty ◽  
Isabelle Leclerc ◽  
Elaine V. Hill ◽  
D. Grahame Hardie ◽  
...  

Glucose-stimulated insulin secretion from pancreatic β-cells requires the kinesin-1/Kif5B-mediated transport of insulin granules along microtubules. 5′-AMPK (5′-AMP-activated protein kinase) is a heterotrimeric serine/threonine kinase which is activated in β-cells at low glucose concentrations, but inhibited as glucose levels increase. Active AMPK blocks glucose-stimulated insulin secretion and the recruitment of insulin granules to the cell surface, suggesting motor proteins may be targets for this kinase. While both kinesin-1/Kif5B and KLC1 (kinesin light chain-1) contain consensus AMPK phosphorylation sites (Thr693 and Ser520, respectively) only recombinant GST (glutathione transferase)–KLC1 was phosphorylated by purified AMPK in vitro. To test the hypothesis that phosphorylation at this site may modulate kinesin-1-mediated granule movement, we developed an approach to study the dynamics of all the resolvable granules within a cell in three dimensions. This cell-wide approach revealed that the number of longer excursions (>10 μm) increased significantly in response to elevated glucose concentration (30 versus 3 mM) in control MIN6 β-cells. However, similar changes were seen in cells overexpressing wild-type KLC1, phosphomimetic (S517D/S520D) or non-phosphorylatable (S517A/S520A) mutants of KLC1. Thus, changes in the phosphorylation state of KLC1 at Ser517/Ser520 seem unlikely to affect motor function.


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