Human islet amyloid polypeptide oligomers disrupt cell coupling, induce apoptosis, and impair insulin secretion in isolated human islets.
Insulin secretion from the 2,000-3,000 beta-cells in an islet is a highly synchronized activity with discharge of insulin in coordinate secretory bursts at approximately 4-min intervals. Insulin secretion progressively declines in type 2 diabetes and following islet transplantation. Both are characterized by the presence of islet amyloid derived from islet amyloid polypeptide (IAPP). In the present studies, we examined the action of extracellular human IAPP (h-IAPP) on morphology and function of human islets. Because oligomers of h-IAPP are known to cause membrane disruption, we questioned if application of h-IAPP oligomers to human islets would lead to disruption of islet architecture (specifically cell-to-cell adherence) and a decrease in coordinate function (e.g., increased entropy of insulin secretion and diminished coordinate secretory bursts). Both hypotheses are affirmed, leading to a novel hypothesis for impaired insulin secretion in type 2 diabetes and following islet transplantation, specifically disrupted cell-to-cell adherence in islets through the actions of membrane-disrupting IAPP oligomers.
Ritzel
Robert A
RA
Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 24-130 Warren Hall, 900 Veteran Ave., Los Angeles, CA 90095-7073, USA.
Meier
Juris J
JJ
Lin
Chia-Yu
CY
Veldhuis
Johannes D
JD
Butler
Peter C
PC
D000682:Amyloid / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects*; D006801:Humans; D020287:In Situ Nick-End Labeling; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D018613:Microscopy, Confocal; D010446:Peptide Fragments / Q000494:pharmacology
D000682:Amyloid; D007328:Insulin; D058228:Islet Amyloid Polypeptide; D010446:Peptide Fragments