title: 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.
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.
  
  
  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.
authors.affiliation: Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, Michigan, USA.
authors.forename: Ismail
authors.initials: I
authors.lastname: Syed
authors.forename: Chandrashekara N
authors.initials: CN
authors.lastname: Kyathanahalli
authors.forename: Bhavaani
authors.initials: B
authors.lastname: Jayaram
authors.forename: Sudha
authors.initials: S
authors.lastname: Govind
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rhodes
authors.forename: Renu A
authors.initials: RA
authors.lastname: Kowluru
authors.forename: Anjaneyulu
authors.initials: A
authors.lastname: Kowluru
mesh_terms: D000818:Animals; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism; D007515:Islets of Langerhans / Q000201:enzymology / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D011924:Rats, Zucker; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D046509:Tissue Culture Techniques; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D048031:JNK Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein