抄録
The c-Jun N-terminal kinases (JNKs) are a subfamily of MAPKs. The JNKs are encoded by three separate genes (jnk1, jnk2, and jnk3), which are spliced alternatively to create ten JNK isoforms that are either p46 or p54 in size. We found that the p52 form of JNK emerged in MOLT-4 or U937 cells following X-irradiation or heat treatment. The accumulation of p52 coincided with the reduction of p54 JNK, while, the amounts of p46 JNK did not change by X-irradiation. Induction of the p52 JNK also paralleled the appearance of the active form of caspase-3, and was suppressed by a caspase-inhibitor, Ac-DEVD-CHO, but not by Ac-YVAD-CHO. In vitro cleavage assays indicated that recombinant JNK1 beta 2 was cleaved by caspase-3, and that the mutation of aspartic acid at position 413 of JNK1 beta 2 to alanine abolished the cleavage. Our results demonstrated that p54 JNKs were new selective targets of caspases, and suggested that the p52 form could serve as an apoptotic marker. [J Radiat Res 44:445 (2003)]
