Lead-stimulated p38MAPK-dependent Hsp27 phosphorylation.
Lead (Pb2+) is a cytotoxic metal ion whose mechanism of action is not established. However, Pb2+ is known to interact with a wide variety of molecules involved in signal transduction. In this study the effect of Pb2+ on protein phosphorylation in bovine adrenal chromaffin cells and human SH SY5Y cells was examined. Cells were incubated with 32P(i) for 1 h in the presence of Pb2+ (1-10 microM) and the proteins were separated by two-dimensional PAGE. An increase in the phosphorylation of a number of proteins was observed in response to Pb2+, including three spots, MW 25 kDa, and pI's in the range 4.0-4.5. These proteins were immunoidentified as three isoforms of the heat-shock protein 27 kDa (Hsp27), and the identity of the most basic spot was confirmed by amino acid sequencing. Phosphorylation of p38MAPK was increased by Pb2+ and the effect of Pb2+ on Hsp27 phosphorylation was blocked by the p38MAPK inhibitor SB203580 (1 microM). The results were similar for bovine chromaffin cells and human SH SY5Y cells. This is the first report showing that Pb2+ can modulate the phosphorylation state of Hsp27 via activation of the p38MAPK pathway.
Leal
Rodrigo B
RB
Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, 88040-900, Brazil. rbleal@yahoo.com.br
Cordova
Fabiano M
FM
Herd
Lynn
L
Bobrovskaya
Larisa
L
Dunkley
Peter R
PR
D000818:Animals; D001345:Autoradiography; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007854:Lead / Q000633:toxicity*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D048051:p38 Mitogen-Activated Protein Kinases
D009363:Neoplasm Proteins; D010710:Phosphates; D007854:Lead; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases