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Protein phosphatase inhibitors and heat preconditioning prevent Hsp27 dephosphorylation, F‐actin disruption and deterioration of morphology in ATP‐depleted endothelial cells
Author(s) -
Loktionova Svetlana A.,
Kabakov Alexander E.
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00920-x
Subject(s) - dephosphorylation , hsp27 , okadaic acid , adenosine triphosphate , microbiology and biotechnology , cytoskeleton , actin cytoskeleton , heat shock protein , actin , biology , phosphatase , phosphorylation , biochemistry , chemistry , hsp70 , cell , gene
The vascular endothelium response to ischemic depletion of ATP was studied in vitro. Endothelial cells (EC) cultured from human aorta or umbilical vein were incubated in a glucose‐free medium containing CCCP or rotenone. Such blockade of energy metabolism caused a drop in ATP, destruction of actin filaments, morphological changes, and eventually disintegration of EC monolayer within 2–2.5 h. While ATP fell and F‐actin collapsed, the 27‐kDa heat shock protein (Hsp27) lost basal phosphorylation and became Triton X‐100‐insoluble forming granules inside the cell nuclei. Protein phosphatase (PP) inhibitors (okadaic acid, cantharidin, sodium orthovanadate) did not delay the ATP decrease in energy‐deprived EC but arrested both the alterations in the Hsp27 status and the changes for the worse in F‐actin and cell morphology. Similarly, the Hsp27 dephosphorylation/insolubilization/granulation and the cytoskeletal and morphological disturbances resulting from lack of ATP were suppressed in heat‐preconditioned (thermotolerant) cultures, this effect being sensitive to quercetin, a blocker of Hsp induction. The longer preservation of the cytosolic pool of phosphorylated Hsp27 during ATP depletion in the PP inhibitor‐treated or thermotolerant EC correlated with the acquired resistance of F‐actin and morphology. These data suggest that PP inhibitors as well as heat‐inducible Hsp(s) can protect ischemia‐stressed cells by preventing the ATP loss‐provoked protein dephosphorylation and breakdown of the actin cytoskeleton.