ATPase activity of the heat shock protein Hsp72 is dispensable for its effects on dephosphorylation of stress kinase JNK and on heat-induced apoptosis

• Published in: FEBS letters Vol. 461; no. 1; pp. 73 - 76
• Main Authors: Volloch, Vladimir, Gabai, Vladimir L., Rits, Sophia, Sherman, Michael Y.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 12.11.1999
• Subjects: Adenosine Triphosphatases - metabolism; Animals; Apoptosis; Cell Line; Fibroblasts - metabolism; Heat shock protein; Heat-Shock Proteins - metabolism; Hsp70 ATPase; HSP72 Heat-Shock Proteins; Humans; Immunoblotting; JNK Mitogen-Activated Protein Kinases; JNK stress kinase; Mitogen-Activated Protein Kinases - metabolism; Phosphorylation; Rats; Recombinant Proteins - metabolism; Signal Transduction; Temperature; Time Factors; Hsp70 ATPase; JNK stress kinase; Heat shock protein; Apoptosis
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(99)01428-3

A major inducible heat shock protein, Hsp72, has previously been found to stimulate dephosphorylation (inactivation) of stress kinase JNK in heat-shocked cells and protect them from apoptosis. Using Rat-1 fibroblasts with constitutive expression of a human Hsp72 or its deletion mutant lacking an ATPase domain (C-terminal fragment (CTF)), we tested whether ATPase activity of Hsp72 is necessary for these effects. We found that expression of CTF markedly increased, similarly to the intact protein, JNK dephosphorylation in heat-shocked cells. As a result, JNK inactivation following heat shock occurred much faster in cells expressing either full-length or mutant Hsp72 than in parental cells and this was accompanied by suppression of heat-induced apoptosis. Thus, protein refolding activity of Hsp72 appears to be dispensable for its effect on JNK inactivation and apoptosis.