Premium
PAK2 is cleaved and activated during hyperosmotic shock‐induced apoptosis via a caspase‐dependent mechanism: Evidence for the involvement of oxidative stress
Author(s) -
Chan WenHsiung,
Yu JauSong,
Yang ShiawDer
Publication year - 1999
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199903)178:3<397::aid-jcp14>3.0.co;2-2
Subject(s) - mechanism (biology) , oxidative stress , apoptosis , microbiology and biotechnology , osmotic shock , caspase , shock (circulatory) , chemistry , osmotic concentration , caspase 3 , oxidative phosphorylation , programmed cell death , biology , biochemistry , medicine , physics , gene , quantum mechanics
Hyperosmotic shock elicits a stress response in mammalian cells and can lead to apoptotic cell death. In the present study, we report that hyperosmotic shock can induce activation of a 36 kDa kinase detected by an in‐gel kinase assay in several cell types, including mouse Balb/c 3T3 fibroblasts, and human Hep 3B and A431 cells. This 36 kDa kinase can be recognized by an antibody against the C‐terminal region of a family of p21 Cdc42/Rac ‐activated kinases (PAKs) on immunoblot. Further studies with this antibody and a PAK2‐specific antibody against the N‐terminal region of PAK2 demonstrate that hyperosmotic shock can induce cleavage of PAK2 to generate a 36 kDa C‐terminal catalytic fragment in cells. The cleavage and activation of PAK2 was found to be closely associated with both DNA fragmentation and activation of an ICE/CED‐3 family cysteine protease termed caspase‐3 in hyperosmotically shocked cells. Furthermore, pretreating the cells with two caspase inhibitors (Ac‐DEVD‐cho and Ac‐YVAD‐cmk) could inhibit both cleavage/activation of PAK2 and DNA fragmentation induced by hyperosmotic shock. Moreover, all these hyperosmotic shock‐induced changes (i.e., activation of caspase‐3, cleavage/activation of PAK2, and DNA fragmentation) in cells could be blocked by antioxidants such as ascorbic acid (vitamine C), α‐tocopherol (vitamine E), dithiothreitol, β‐mercaptoethanol, and glutathione. Taken together, our results show that PAK2 is cleaved and activated via a caspase‐dependent mechanism during hyperosmotic shock–induced apoptosis and suggest the involvement of antioxidant‐preventable oxidative stress in inducing this process. J. Cell. Physiol. 178:397–408, 1999. © 1999 Wiley‐Liss, Inc.