In spermatozoa, Stat1 is activated during capacitation and the acrosomal reaction

A role for sperm-specific proteins during the early embryonic development has been suggested by a number of recent studies. However, little is known about the participation of transcription factors in that stage. Here, we show that the signal transducer and activator of transcription 1 (Stat1), but not Stat4, was phosphorylated in response to capacitation and the acrosomal reaction (AR). Moreover, Stat1 phosphorylation correlatedwith changes in its localization: during capacitation, Stat1 moved fromthe cytoplasmto the theca/flagellumfraction.DuringAR, Stat1 phosphorylation increased again. In addition, blocking protein kinaseA (PKA) and PKC during capacitation abolished both phosphorylation andmigration of Stat1.Our results showtight spatiotemporal rearrangements of Stat1, suggesting that after fertilization Stat1 participates in the first rounds of transcription within the male pronucleus.