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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

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 componen...

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Detalles Bibliográficos
Autores principales: Syed, Ismail, Kyathanahalli, Chandrashekara N., Jayaram, Bhavaani, Govind, Sudha, Rhodes, Christopher J., Kowluru, Renu A., Kowluru, Anjaneyulu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Diabetes Association 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3198065/
https://www.ncbi.nlm.nih.gov/pubmed/21911753
http://dx.doi.org/10.2337/db11-0809
Descripción
Sumario: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.