cDNA cloning and functional characterization of Xenopus laevis DNase gamma

We report here the cDNA cloning and functional analysis of Xenopus DNase gamma (xDNase gamma). Two forms of cDNAs are isolated from adult spleen: one composing a 933 bp open reading frame for the enzymatically active xDNase gamma protein, and the other encoding an inactive short alternative form. Northern blot analysis revealed that the xDNase gamma mRNA is expressed in spleen, liver, testis, and ovary. xDNase gamma expression is scarcely detected in the tail muscle of tadpoles; however, it increases during metamorphosis and reaches a maximum during the late metamorphic climax. The ectopic expression of xDNase gamma results in the appearance of extensive DNA fragmentation in C2C12 myoblasts after the induction of apoptosis. In contrast, Xenopus DNase I fails to induce apoptotic DNA ladder formation under the same conditions. Our results suggest a possible involvement of xDNase gamma in apoptosis during amphibian metamorphosis.