The Caenorhabditis elegans heterochronic gene lin-29 coordinates the vulval-uterine-epidermal connections

Background: The development of a connection between the uterus and the vulv a in the nematode Caenorhabditis elegans requires specification of a uterin e cell called the utse, and its attachment to the vulva and the epidermal s eam cells. The uterine pi cells generate the utse and uv1 cells, which also connect the uterus to the vulva. The uterine anchor cell (AC) induces the vulva through LIN-3/epidermal growth factor (EGF) signaling, and the pi cel ls through LIN-12/Notch signaling. Here, we report that a gene required for seam cell maturation is also required for specification of the utse and fo r vulval differentiation, and thus helps to coordinate development of the v ulval-uterine-seam cell connection. Results: We cloned the egl-29 gene, which is necessary for induction of ute rine pi cells, and found it to be allelic to lin-29, which encodes a zinc f inger transcription factor that is necessary for the terminal differentiati on of epidermal seam cells. In the uterus, lin-29 functioned upstream of li n-12 in the induction of pi cells and was necessary to maintain expression in the AC of lag-2, which encodes a ligand for LIN-12. Conclusions: The lin-29 gene controls gene expression in the epidermal seam cells, uterus and vulva, and may help to coordinate the terminal developme nt of these three tissues by regulating the timing of late gene expression during organogenesis.