Fig. 7.

Model for RNT-1/BRO-1-mediated repression of POP-1. The RNT-1/BRO-1 repressor reduces the overall POP-1 expression levels in early L2-stage seam cells below the level needed for transcriptional repression and differentiation induction, thereby converting asymmetric to symmetric division (left panel). RNT-1 is degraded during the L2 symmetric division (dashed outline) and POP-1 expression is no longer repressed, causing a switch from symmetric cell division back to asymmetric cell division (middle panel). Heat shock-induced increased expression of RNT-1/BRO-1 reduces POP-1 expression levels, converting the original asymmetric seam cell division into a symmetric division (right panel).