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Activation of a PKC is required for vanadate-induced phosphorylation of protein kinase B (Akt), but not p70S6k in mouse epidermal JB6 cells.

Authors
Li-J; Dokka-S; Wang-L; Shi-X; Castranova-V; Yan-Y; Costa-M; Huang-C
Source
Mol Cell Biochem 2004 Jan; 255(1-2):217-225
NIOSHTIC No.
20024189
Abstract
Vanadium is a metal widely distributed in the environment. Although vanadate-containing compounds exert potent toxic effects on a wide variety of biological systems, the mechanisms by which vanadate mediates adverse effects are not well understood. The present study investigated the vanadate-induced phosphorylation of Akt and p70S6K, two kinases known to be vital for cell survival, growth, transformation, and transition of the cell cycle in mammals. Exposure of mouse epidermal JB6 cells to vanadium led to phosphorylation of Akt and p70S6K in a time- and dose-dependent manner. Vanadium exposure also caused translocation of atypical isoforms of PKC (gamma, zeta) from the cytosol to the membrane, but had no effect on PKCa translocation, suggesting that the atypical PKCs (aPKC) were specifically involved in vanadium-induced cellular response. Importantly, overexpression of a dominant negative mutant PKCgamma blocked Akt phosphorylation at Ser473 and Thr308, whereas it did not inhibit p70S6k phosphorylation at Thr389 and Thr421/Ser424, suggesting that aPKC activation is specifically involved in vanadium-induced activation of Akt, but not in activation of p70S6k. Furthermore, vanadium-induced p70S6k phosphorylation at Thr389 and Thr421/Ser424 and Akt phosphorylation at Thr308 occurred through a PI-3K-dependent pathway because a PI-3K dominant negative mutant inhibited induction as compared with vector control cells. These results indicate that there was a differential role of aPKC in vanadate-induced phosphorylation of Akt and p70S6k, suggesting that signal transduction pathways leading to the activation of Akt and p70S6k were different.
Keywords
Toxic-effects; Biological-systems; Biological-transport; Biological-monitoring; Animals; Animal-studies; Cellular-reactions
Contact
Jingxia Li, Nelson Institute of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10987, USA
CODEN
MCBIB8
CAS No.
7440-62-2
Publication Date
20040101
Document Type
Journal Article
Email Address
chuanshu@env.med.nyu.edu
Fiscal Year
2004
NTIS Accession No.
NTIS Price
Issue of Publication
1-2
ISSN
0300-8177
NIOSH Division
HELD
Source Name
Molecular and Cellular Biochemistry
State
NY; WV
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