ERKs and p38 kinases mediate ultraviolet B-induced phosphorylation of histone H3 at serine 10

Histone H3 is the core protein of the nucleosome. Phosphorylation of H3 inv olves immediate early gene expression, chromatin remodeling, and chromosome condensation during mitosis. Very recently, Rsk2 or MSK1 kinase-mediated p hosphorylation of H3 at serine 10 was reported. In the present study, we sh ow that both ERKs and p38 kinase may mediate ultraviolet B-induced phosphor ylation of H3 at serine 10. PD 98059, a MEK1 inhibitor, and SE 202190, a p3 8 kinase inhibitor, efficiently inhibited ultraviolet B-induced phosphoryla tion of H3. Phosphorylation of H3 was also inhibited in cells expressing do minant negative mutant (DNM) ERK2 and DNM p38 kinase. In contrast, no inhib ition of H3 phosphorylation in Jnk1 or Jnk2 knockout cells (Jnk1(-/-) or Jn k2(-/-)) and cells expressing DNM JNK1 was observed. More importantly, incu bation of active ERK2 or p38 kinase with H3 protein resulted in phosphoryla tion of H3 at serine 10 in vitro. These results suggest that ERK and p38 ki nase are at least two important mediators of phosphorylation of H3 at serin e 10.