Activation of hPAK65 by caspase cleavage induces some of the morphological and biochemical changes of apoptosis.
Apoptosis is a highly regulated form of cell death, characterized by distinctive features such as cellular shrinkage and nuclear condensation. We demonstrate here that proteolytic activation of hPAK65, a p21-activated kinase, induces morphological changes and elicits apoptosis. hPAK65 is cleaved both in vitro and in vivo by caspases at a single site between the N-terminal regulatory p21-binding domain and the C-terminal kinase domain. The C-terminal cleavage product becomes activated, with a kinetic profile that parallels caspase activation during apoptosis. This C-terminal hPAK65 fragment also activates the c-Jun N-terminal kinase pathway in vivo. Microinjection or transfection of this truncated hPAK65 causes striking alterations in cellular and nuclear morphology, which subsequently promotes apoptosis in both CHO and Hela cells. Conversely, apoptosis is delayed in cells expressing a dominant-negative form of hPAK65. These findings provide a direct evidence that the activated form of hPAK65 generated by caspase cleavage is a proapoptotic effector that mediates morphological and biochemical changes seen in apoptosis.
Lee
N
N
Chiron Technologies, Chiron Corporation, 4560 Horton Street, Emeryville, CA 94608, USA.
MacDonald
H
H
Reinhard
C
C
Halenbeck
R
R
Roulston
A
A
Shi
T
T
Williams
L T
LT
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases; D002460:Cell Line; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D051381:Rats; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D013379:Substrate Specificity; D014162:Transfection
D019893:Ribosomal Protein S6 Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases