Increased Phagocyte-like NADPH Oxidase and ROS Generation in Type 2 Diabetic ZDF Rat and Human Islets: Role of Rac1-JNK1/2 Signaling Pathway in Mitochondrial Dysregulation in the Diabetic Islet

Overview

Journal Diabetes

Specialty Endocrinology

Date 2011 Sep 14

PMID 21911753

Citations 68

Authors

Ismail Syed

Chandrashekara N Kyathanahalli

Bhavaani Jayaram

Sudha Govind

Christopher J Rhodes

Renu A Kowluru

Anjaneyulu Kowluru

Affiliations

Soon will be listed here.

Abstract

Objective: To determine the subunit expression and functional activation of phagocyte-like NADPH oxidase (Nox), reactive oxygen species (ROS) generation and caspase-3 activation in the Zucker diabetic fatty (ZDF) rat and diabetic human islets.

Research Design And Methods: Expression of core components of Nox was quantitated by Western blotting and densitometry. ROS levels were quantitated by the 2',7'-dichlorofluorescein diacetate method. Rac1 activation was quantitated using the gold-labeled immunosorbent assay kit.

Results: Levels of phosphorylated p47(phox), active Rac1, Nox activity, ROS generation, Jun NH(2)-terminal kinase (JNK) 1/2 phosphorylation, and caspase-3 activity were significantly higher in the ZDF islets than the lean control rat islets. Chronic exposure of INS 832/13 cells to glucolipotoxic conditions resulted in increased JNK1/2 phosphorylation and caspase-3 activity; such effects were largely reversed by SP600125, a selective inhibitor of JNK. Incubation of normal human islets with high glucose also increased the activation of Rac1 and Nox. Lastly, in a manner akin to the ZDF diabetic rat islets, Rac1 expression, JNK1/2, and caspase-3 activation were also significantly increased in diabetic human islets.

Conclusions: We provide the first in vitro and in vivo evidence in support of an accelerated Rac1-Nox-ROS-JNK1/2 signaling pathway in the islet β-cell leading to the onset of mitochondrial dysregulation in diabetes.

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