STAT SIGNALING IS ACTIVE DURING EARLY MAMMALIAN DEVELOPMENT

Cytokine activation of gene expression can be mediated through signal transducer and activator of transcription (STAT) signaling pathways re sulting in expression of target genes, Because many cytokines have imp ortant regulatory roles during early development, we wanted to ascerta in whether STAT signaling was also active at this time and could there fore have important roles in mediating developmental processes. We hav e found that Stat1 and Stat3 mRNAs are present in both maternal and ex traembryonic tissues during early postimplantation stages of murine de velopment. Furthermore, analyses of STAT activity in E4.5-E9.5 decidua l swellings by electrophoretic mobility shift assay demonstrated that Stat3 protein was active during this early developmental period. The i dentification of activated Stat3 demonstrates that STAT signaling func tions during early postimplantation development in the mouse are likel y to be important during early embryogenesis. (C) 1997 Wiley-Liss, Inc .