Activation of Rac1 increases c-Jun NH(2)-terminal kinase activity and DNA fragmentation in a calcium-dependent manner in rat myoblast cell line H9c2.
We examined the role of intracellular Ca(2+) in c-Jun NH(2)-terminal kinase (JNK) activation and DNA fragmentation in the rat myoblast cell line H9c2 using small GTP-binding protein Rac1. A constitutively active mutant of Rac1 (V12-Rac1) increased JNK-responsive gene expression 6-fold, although this increase was attenuated by the intracellular Ca(2+) chelator BAPTA-AM. V12-Rac1 also increased the number of DNA fragmentated cells. However, V12-Rac1-mediated JNK activation was not affected by BAPTA-AM as determined by direct measurement of active forms, and V12-Rac1 did not affect intracellular Ca(2+) concentration. These results suggest that Rac1 can activate JNK and induces cell injury, but [Ca(2+)](i) is necessary for V12-Rac1 to induce DNA fragmentation downstream of JNK activation.
Nishida
M
M
Graduate School of Pharmaceutical Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Nagao
T
T
Kurose
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D053938:DNA Fragmentation; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein
D018797:Cell Cycle Proteins; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D002118:Calcium