Co-regulation by Notch and Fos is required for cell fate specification of intermediate precursors during C. elegans uterine development

Abstract

The Notch pathway is the key signal for many cell fate decisions in the nematode Caenorhabditis elegans including the uterine π cell fate, crucial for a proper uterine-vulval connection and egg laying. Expression of the egl-13 SOX domain transcription factor is specifically upregulated upon induction of the π lineage and not in response to other LIN-12/Notch-mediated decisions. We determined that dual regulation by LIN-12 and FOS-1 is required for egl-13 expression at specification and for complete rescue of egl-13 mutants. We found that fos-1 mutants exhibit uterine defects and fail to express π markers. We show that FOS-1 is expressed at π cell specification and can bind in vitro to egl-13 upstream regulatory sequence (URS) as a heterodimer with C. elegans Jun.