TY - JOUR
T1 - Adenoviral overexpression of the glutamylcysteine ligase catalytic subunit protects pancreatic islets against oxidative stress
AU - Tran, Phuong Oanh T.
AU - Parker, Sarah M.
AU - LeRoy, Eric
AU - Franklin, Christopher C.
AU - Kavanagh, Terrance J.
AU - Zhang, Tao
AU - Zhou, Huarong
AU - Vliet, Portia
AU - Oseid, Elizabeth
AU - Harmon, Jamie S.
AU - Robertson, R. Paul
PY - 2004/12/24
Y1 - 2004/12/24
N2 - The catalytic subunit of glutamylcysteine ligase (GCLC) primarily regulates de novo synthesis of glutathione (GSH) in mammalian cells and is central to the antioxidant capacity of the cell. However, GCLC expression in pancreatic islets has not been previously examined. We designed experiments to ascertain whether GCLC is normally expressed in islets and whether it is up-regulated by interleukin-1β (IL-1β). GCLC expression levels were intermediate compared with other metabolic tissues (kidney, liver, muscle, fat, and lung). IL-1β up-regulated GCLC expression (10 ng/ml IL-1β, 3.76 ± 0.86; 100 ng/ml IL-1β, 4.22 ± 0.68-fold control) via the p38 form of mitogen-activated protein kinase and NFκB and also increased reactive oxygen species levels (10 ng/ml IL-1β, 5.41 ± 1.8-fold control). This was accompanied by an increase in intraislet GSH/GSSG ratio (control, 7.1 ± 0.1; 10 ng/ml IL-1β, 8.0 ± 0.5; 100 ng/ml IL-1β, 8.2 ± 0.5-fold control; p < 0.05). To determine whether overexpression of GCLC increases the antioxidant capacity of the islet and prevents the adverse effects of IL-1β on glucose-induced insulin secretion, islets were infected with an adenovirus encoding GCLC. IL-1β significantly decreased glucose-stimulated insulin secretion (control, 123.8 ± 17.7; IL-1β, 40.2 ± 3.9 microunits/ml insulin/islet). GCLC overespression increased intraislet GSH levels and partially prevented the decrease in glucose-stimulated insulin secretion caused by IL-1β. These data provide the first report of GCLC expression in the islet and demonstrate that adenoviral overexpression of GCLC increases intracellular GSH levels and protects the beta cell from the adverse effects of IL-1β.
AB - The catalytic subunit of glutamylcysteine ligase (GCLC) primarily regulates de novo synthesis of glutathione (GSH) in mammalian cells and is central to the antioxidant capacity of the cell. However, GCLC expression in pancreatic islets has not been previously examined. We designed experiments to ascertain whether GCLC is normally expressed in islets and whether it is up-regulated by interleukin-1β (IL-1β). GCLC expression levels were intermediate compared with other metabolic tissues (kidney, liver, muscle, fat, and lung). IL-1β up-regulated GCLC expression (10 ng/ml IL-1β, 3.76 ± 0.86; 100 ng/ml IL-1β, 4.22 ± 0.68-fold control) via the p38 form of mitogen-activated protein kinase and NFκB and also increased reactive oxygen species levels (10 ng/ml IL-1β, 5.41 ± 1.8-fold control). This was accompanied by an increase in intraislet GSH/GSSG ratio (control, 7.1 ± 0.1; 10 ng/ml IL-1β, 8.0 ± 0.5; 100 ng/ml IL-1β, 8.2 ± 0.5-fold control; p < 0.05). To determine whether overexpression of GCLC increases the antioxidant capacity of the islet and prevents the adverse effects of IL-1β on glucose-induced insulin secretion, islets were infected with an adenovirus encoding GCLC. IL-1β significantly decreased glucose-stimulated insulin secretion (control, 123.8 ± 17.7; IL-1β, 40.2 ± 3.9 microunits/ml insulin/islet). GCLC overespression increased intraislet GSH levels and partially prevented the decrease in glucose-stimulated insulin secretion caused by IL-1β. These data provide the first report of GCLC expression in the islet and demonstrate that adenoviral overexpression of GCLC increases intracellular GSH levels and protects the beta cell from the adverse effects of IL-1β.
UR - http://www.scopus.com/inward/record.url?scp=19944429847&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=19944429847&partnerID=8YFLogxK
U2 - 10.1074/jbc.M404809200
DO - 10.1074/jbc.M404809200
M3 - Article
C2 - 15485876
AN - SCOPUS:19944429847
VL - 279
SP - 53988
EP - 53993
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 52
ER -