Brinker requires two co repressors for maximal and versatile repression inDpp signalling

decapentaplegic (dpp) encodes a Drosophila transforming growth factor-beta homologue that functions as a morphogen in the developing embryo and in adu lt appendage formation. In the wing imaginal disc, a Dpp gradient governs p atterning along the anteroposterior axis by inducing regional expression of diverse genes in a concentration-dependent manner. Recent studies show tha t responses to graded Dpp activity also require an input from a complementa ry and opposing gradient of Brinker (Brk), a transcriptional repressor prot ein encoded by a Dpp target gene. Here we show that Brk harbours a function al and transferable repression domain, through which it recruits the corepr essors Groucho and CtBP. By analysing transcriptional outcomes arising from the genetic removal of these corepressors, and by ectopically expressing B rk variants in the embryo, we demonstrate that these corepressors are alter natively used by Brk for repressing some Dpp-responsive genes, whereas for repressing other distinct target genes they are not required. Our results s how that Brk utilizes multiple means to repress its endogenous target genes , allowing repression of a multitude of complex Dpp target promoters.