These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Modulation of insulin effects on phosphorylation of protein kinase B and glycogen synthesis by tumor necrosis factor-alpha in HepG2 cells.
    Author: Gupta D, Khandelwal RL.
    Journal: Biochim Biophys Acta; 2004 Mar 17; 1671(1-3):51-8. PubMed ID: 15026145.
    Abstract:
    The effects of tumor necrosis factor-alpha (TNF-alpha) on insulin-induced phosphorylation of protein kinase B-alpha (PKB-alpha) and downstream enzyme glycogen synthase kinase-3 beta (GSK-3 beta) was examined in HepG2 liver cells. The exogenous treatment of HepG2 cells with TNF-alpha for 1 h caused phosphorylation of Ser473 and Thr308 residues of PKB-alpha. The maximal phosphorylation (approximately 4-fold) was obtained with 1 ng/ml TNF-alpha and no further increase was observed with higher concentrations of this cytokine. The cells pretreated with TNF-alpha for 1 h followed by incubation with insulin (10 nM) showed near additive effect on phosphorylation of PKB-alpha and downstream enzyme GSK-3 beta. The long-term (4, 8, 24 h) exogenous treatment of cells with optimal (1 ng/ml) concentration of TNF-alpha also caused phosphorylation of PKB-alpha, albeit to a lesser degree. However, long-term pretreatments of cells with TNF-alpha reduced insulin-stimulated phosphorylation of PKB-alpha and GSK-3 beta. Short- and long-term preincubation of HepG2 cells with TNF-alpha also resulted in parallel changes in glycogen synthesis in the presence of insulin. In fact, long-term preincubation with TNF-alpha completely abolished the insulin-induced glycogen synthesis. These results suggest that short-term exposure to TNF-alpha augments insulin effects whereas long-term exposure causes insulin resistance in HepG2 cells.
    [Abstract] [Full Text] [Related] [New Search]