Faculty Collaboration Database

Double-stranded RNA-dependent protein kinase is not required for double-stranded RNA-induced nitric oxide synthase expression or nuclear factor-kappaB activation by islets. Diabetes 2001 Feb;50(2):283-90

Date

03/29/2001

Pubmed ID

11272138

DOI

10.2337/diabetes.50.2.283

Scopus ID

2-s2.0-0035140170 (requires institutional sign-in at Scopus site)   23 Citations

Abstract

Environmental factors, such as viral infection, have been implicated in the destruction of beta-cells during the development of autoimmune diabetes. Double-stranded RNA (dsRNA), produced during viral replication, is an active component of a viral infection that stimulates antiviral responses in infected cells. Previous studies have shown that treatment of rat islets with dsRNA in combination with gamma-interferon (IFN-gamma) results in a nitric oxide-dependent inhibition of glucose-stimulated insulin secretion. This study examines the role of nuclear factor-kappaB (NF-kappaB) and the dsRNA-dependent protein kinase (PKR) in dsRNA + IFN-gamma-induced nitric oxide synthase (iNOS) expression and nitric oxide production by rat, mouse, and human islets. Treatment of rat and human islets with dsRNA in the form of polyinosinic-polycytidylic acid (poly IC) and IFN-gamma resulted in iNOS expression and nitric oxide production. Inhibitors of NF-kappaB activation-the proteasome inhibitor MG-132 and the antioxidant pyrrolidine-dithiocarbamate (PDTC)-prevented poly IC + IFN-gamma-induced iNOS expression and nitric oxide production. Incubation of rat islets for 3 h or human islets for 2 h with poly IC alone or poly IC + IFN-gamma resulted in NF-kappaB nuclear translocation and degradation of the NF-kappaB inhibitor protein, IkappaB, events that are prevented by MG-132. PKR has been shown to participate in dsRNA-induced NF-kappaB activation in a number of cell types, including mouse embryonic fibroblasts. However, poly IC stimulated NF-kappaB nuclear translocation and IkappaB degradation to similar levels in islets isolated from mice devoid of PKR (PKR-/-) and wild-type mice (PKR+/+). Furthermore, the genetic absence of PKR did not affect dsRNA + IFN-gamma-induced iNOS expression, nitric oxide production, or the inhibitory actions of these agents on glucose-stimulated insulin secretion. These results suggest that 1) NF-KB activation is required for dsRNA + IFN-gamma-induced iNOS expression, 2) PKR is not required for either dsRNA-induced NF-kappaB activation or dsRNA + IFN-y-induced iNOS expression by islets, and 3) PKR is not required for dsRNA + IFN-gamma-induced inhibition of glucose-stimulated insulin secretion by islets.

Author List

Blair LA, Heitmeier MR, Scarim AL, Maggi LB Jr, Corbett JA

Author

John A. Corbett PhD Chair, Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Antioxidants
Cysteine Proteinase Inhibitors
Drug Combinations
Enzyme Induction
Female
Glucose
Humans
Insulin
Interferon-gamma
Islets of Langerhans
Leupeptins
Male
Mice
Mice, Inbred C57BL
NF-kappa B
Nitric Oxide Synthase
Nitric Oxide Synthase Type II
Nitrites
Poly I-C
Pyrrolidines
Rats
Rats, Sprague-Dawley
Thiocarbamates
eIF-2 Kinase