scholarly journals RORB and RORC associate with human islet dysfunction and inhibit insulin secretion in INS-1 cells

Islets ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Jalal Taneera ◽  
Abdul Khader Mohammed ◽  
Sarah Dhaiban ◽  
Mawieh Hamad ◽  
Rashmi B. Prasad ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Human Islet ◽  
Islet Dysfunction ◽  
Inhibit Insulin Secretion

scholarly journals Identification of a small molecule that stimulates human β-cell proliferation and insulin secretion, and protects against cytotoxic stress in rat insulinoma cells

2019 ◽  
Author(s):  
Hans E. Hohmeier ◽  
Lu Zhang ◽  
Brandon Taylor ◽  
Samuel Stephens ◽  
Peter McNamara ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Insulin Secretion ◽  
Small Molecule ◽  
Islet Cell ◽  
Human Islet ◽  
Luciferase Reporter ◽  
Β Cell ◽  
Cytotoxic Stress ◽  
Insulinoma Cells ◽  
Rat Insulinoma

AbstractA key event in the development of both major forms of diabetes is the loss of functional pancreatic islet β-cell mass. Strategies aimed at enhancing β-cell regeneration have long been pursued, but methods for reliably inducing human β-cell proliferation with full retention of key functions such as glucose-stimulated insulin secretion (GSIS) are still very limited. We have previously reported that overexpression of the homeobox transcription factor Nkx6.1 stimulates β-cell proliferation, while also enhancing GSIS and providing protection against β-cell cytotoxicity through induction of the VGF prohormone. We developed an Nkx6.1 pathway screen by stably transfecting 832/13 rat insulinoma cells with a VGF promoter-luciferase reporter construct, using the resultant cell line to screen a 630,000 compound chemical library. We isolated three compounds with consistent effects to stimulate human islet cell proliferation. Further studies of the most potent of these compounds, GNF-9228, revealed that it selectively activates human β-cell relative to α-cell proliferation and has no effect on δ-cell replication. In addition, pre-treatment, but not short term exposure of human islets to GNF-9228 enhances GSIS. GNF-9228 also protects 832/13 insulinoma cells against ER stress- and inflammatory cytokine-induced cytotoxicity. In contrast to recently emergent Dyrk1a inhibitors that stimulate human islet cell proliferation, GNF-9228 does not activate NFAT translocation. These studies have led to identification of a small molecule with pleiotropic positive effects on islet biology, including stimulation of human β-cell proliferation and insulin secretion, and protection against multiple agents of cytotoxic stress.

scholarly journals Hypoglycemia and Islet Dysfunction Following Oral Glucose Tolerance Testing in Pancreatic-Insufficient Cystic Fibrosis

2020 ◽  
Vol 105 (10) ◽  
pp. 3179-3189
Author(s):  
Marissa J Kilberg ◽  
Clea Harris ◽  
Saba Sheikh ◽  
Darko Stefanovski ◽  
Marina Cuchel ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Early Phase ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Insulin Effect ◽  
Secretory Rate ◽  
C Peptide ◽  
Islet Dysfunction

Abstract Context Oral glucose tolerance test (OGTT)-related hypoglycemia is common in pancreatic-insufficient cystic fibrosis (PI-CF), but its mechanistic underpinnings are yet to be established. Objective To delineate the mechanism(s) underlying OGTT-related hypoglycemia. Design and Setting We performed 180-minute OGTTs with frequent blood sampling in adolescents and young adults with PI-CF and compared results with those from a historical healthy control group. Hypoglycemia (Hypo[+]) was defined as plasma glucose <65 mg/dL. We hypothesized that CF-Hypo[+] would demonstrate impaired early phase insulin secretion and persistent late insulin effect compared with control-Hypo[+], and explored the contextual counterregulatory response. Main Outcome Measure OGTT 1-hour and nadir glucose, insulin, C-peptide, and insulin secretory rate (ISR) incremental areas under the curve (AUC) between 0 and 30 minutes (early) and between 120 and 180 minutes (late), and Δglucagon120-180min and Δfree fatty acids (FFAs)120-180min were compared between individuals with CF and control participants with Hypo[+]. Results Hypoglycemia occurred in 15/23 (65%) patients with CF (43% female, aged 24.8 [14.6-30.6] years) and 8/15 (55%) control participants (33% female, aged 26 [21-38] years). The CF-Hypo[+] group versus the control-Hypo[+] group had higher 1-hour glucose (197 ± 49 vs 139 ± 53 mg/dL; P = 0.05) and lower nadir glucose levels (48 ± 7 vs 59 ± 4 mg/dL; P < 0.01), while insulin, C-peptide, and ISR-AUC0-30 min results were lower and insulin and C-peptide, and AUC120-180min results were higher (P < 0.05). Individuals with CF-Hypo[+] had lower Δglucagon120-180min and ΔFFA120-180min compared with the control-Hypo[+] group (P < 0.01). Conclusions OGTT-related hypoglycemia in PI-CF is associated with elevated 1-hour glucose, impaired early phase insulin secretion, higher late insulin exposure, and less increase in glucagon and FFAs. These data suggest that hypoglycemia in CF is a manifestation of islet dysfunction including an impaired counterregulatory response.

scholarly journals Selective Serotonin Reuptake Inhibitors (SSRIs) Inhibit Insulin Secretion and Action in Pancreatic β Cells

2012 ◽  
Vol 288 (8) ◽  
pp. 5682-5693 ◽  
Author(s):  
Roi Isaac ◽  
Sigalit Boura-Halfon ◽  
Diana Gurevitch ◽  
Alla Shainskaya ◽  
Yechiel Levkovitz ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Serotonin Reuptake ◽  
Selective Serotonin Reuptake Inhibitors ◽  
Serotonin Reuptake Inhibitors ◽  
Selective Serotonin ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Inhibit Insulin Secretion

scholarly journals Lipid Modulation in the Formation of β-Sheet Structures. Implications for De Novo Design of Human Islet Amyloid Polypeptide and the Impact on β-Cell Homeostasis

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1201 ◽  
Author(s):  
Israel Martínez-Navarro ◽  
Raúl Díaz-Molina ◽  
Angel Pulido-Capiz ◽  
Jaime Mas-Oliva ◽  
Ismael Luna-Reyes ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Membrane Lipids ◽  
Islet Amyloid Polypeptide ◽  
Human Islet ◽  
Β Cells ◽  
Islet Amyloid ◽  
Human Islet Amyloid Polypeptide ◽  
Insulin Granules ◽  
The Impact ◽  
Β Sheet

Human islet amyloid polypeptide (hIAPP) corresponds to a 37-residue hormone present in insulin granules that maintains a high propensity to form β-sheet structures during co-secretion with insulin. Previously, employing a biomimetic approach, we proposed a panel of optimized IAPP sequences with only one residue substitution that shows the capability to reduce amyloidogenesis. Taking into account that specific membrane lipids have been considered as a key factor in the induction of cytotoxicity, in this study, following the same design strategy, we characterize the effect of a series of lipids upon several polypeptide domains that show the highest aggregation propensity. The characterization of the C-native segment of hIAPP (residues F23-Y37), together with novel variants F23R and I26A allowed us to demonstrate an effect upon the formation of β-sheet structures. Our results suggest that zwitterionic phospholipids promote adsorption of the C-native segments at the lipid-interface and β-sheet formation with the exception of the F23R variant. Moreover, the presence of cholesterol did not modify this behavior, and the β-sheet structural transitions were not registered when the N-terminal domain of hIAPP (K1-S20) was characterized. Considering that insulin granules are enriched in phosphatidylserine (PS), the property of lipid vesicles containing negatively charged lipids was also evaluated. We found that these types of lipids promote β-sheet conformational transitions in both the C-native segment and the new variants. Furthermore, these PS/peptides arrangements are internalized in Langerhans islet β-cells, localized in the endoplasmic reticulum, and trigger critical pathways such as unfolded protein response (UPR), affecting insulin secretion. Since this phenomenon was associated with the presence of cytotoxicity on Langerhans islet β-cells, it can be concluded that the anionic lipid environment and degree of solvation are critical conditions for the stability of segments with the propensity to form β-sheet structures, a situation that will eventually affect the structural characteristics and stability of IAPP within insulin granules, thus modifying the insulin secretion.

N-Terminally elongated fragments of galanin(1–16) inhibit insulin secretion from isolated mouse islets

1994 ◽  
Vol 53 (1) ◽  
pp. 31-37 ◽  
Author(s):  
S. Gregersen ◽  
Ü. Langel ◽  
T. Bartfai ◽  
B. Ahrén
Keyword(s):  
Insulin Secretion ◽  
Mouse Islets ◽  
Inhibit Insulin Secretion

scholarly journals PKA-dependent potentiation of glucose-stimulated insulin secretion by Epac activator 8-pCPT-2′-O-Me-cAMP-AM in human islets of Langerhans

2010 ◽  
Vol 298 (3) ◽  
pp. E622-E633 ◽  
Author(s):  
Oleg G. Chepurny ◽  
Grant G. Kelley ◽  
Igor Dzhura ◽  
Colin A. Leech ◽  
Michael W. Roe ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Islets Of Langerhans ◽  
Human Islets ◽  
Human Islet ◽  
Second Phase ◽  
Acetoxymethyl Ester ◽  
Insulin Secretagogue ◽  
Camp Analog ◽  
Human Islets Of Langerhans ◽  
Glucose Stimulated Insulin Secretion

Potential insulin secretagogue properties of an acetoxymethyl ester of a cAMP analog (8-pCPT-2′- O-Me-cAMP-AM) that activates the guanine nucleotide exchange factors Epac1 and Epac2 were assessed using isolated human islets of Langerhans. RT-QPCR demonstrated that the predominant variant of Epac expressed in human islets was Epac2, although Epac1 was detectable. Under conditions of islet perifusion, 8-pCPT-2′- O-Me-cAMP-AM (10 μM) potentiated first- and second-phase 10 mM glucose-stimulated insulin secretion (GSIS) while failing to influence insulin secretion measured in the presence of 3 mM glucose. The insulin secretagogue action of 8-pCPT-2′- O-Me-cAMP-AM was associated with depolarization and an increase of [Ca2+]i that reflected both Ca2+ influx and intracellular Ca2+ mobilization in islet β-cells. As expected for an Epac-selective cAMP analog, 8-pCPT-2′- O-Me-cAMP-AM (10 μM) failed to stimulate phosphorylation of PKA substrates CREB and Kemptide in human islets. Furthermore, 8-pCPT-2′- O-Me-cAMP-AM (10 μM) had no significant ability to activate AKAR3, a PKA-regulated biosensor expressed in human islet cells by viral transduction. Unexpectedly, treatment of human islets with an inhibitor of PKA activity (H-89) or treatment with a cAMP antagonist that blocks PKA activation (Rp-8-CPT-cAMPS) nearly abolished the action of 8-pCPT-2′- O-Me-cAMP-AM to potentiate GSIS. It is concluded that there exists a permissive role for PKA activity in support of human islet insulin secretion that is both glucose dependent and Epac regulated. This permissive action of PKA may be operative at the insulin secretory granule recruitment, priming, and/or postpriming steps of Ca2+-dependent exocytosis.

scholarly journals In vivo studies of glucagon secretion by human islets transplanted in mice

2019 ◽  
Author(s):  
Krissie Tellez ◽  
Yan Hang ◽  
Xueying Gu ◽  
Roland W. Stein ◽  
Seung K. Kim
Keyword(s):  
Insulin Secretion ◽  
Islet Transplantation ◽  
Glucagon Secretion ◽  
Human Islets ◽  
Human Islet ◽  
In Vivo Studies ◽  
Cell Regulation ◽  
Cell Hyperplasia ◽  
Human Islet Transplantation

AbstractRelatively little is known about regulated glucagon secretion by human islet α cells compared to insulin secretion from β cells, despite conclusive evidence of dysfunction in both cell types in diabetes mellitus. Distinct insulin sequences in humans and mice permit in vivo studies of β cell regulation after human islet transplantation in immunocompromised mice, whereas identical glucagon sequences prevent analogous in vivo measures of glucagon output from human α cells. We used CRISPR/Cas9 genome editing to remove glucagon-encoding codons 2-29 in immunocompromised (NSG) mice, preserving production of other proglucagon-derived hormones, like Glucagon-like-peptide 1. These NSG-Glucagon knockout (NSG-GKO) mice had phenotypes associated with glucagon signaling deficits, including hypoglycemia, hyperaminoacidemia, hypoinsulinemia, and islet α cell hyperplasia. NSG-GKO host metabolic and islet phenotypes reverted after human islet transplantation, and human islets retained regulated glucagon and insulin secretion. NSG-GKO mice provide an unprecedented resource to investigate unique, species-specific human α cell regulation in vivo.

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