Ciliary and extraciliary Gpr161 pools repress hedgehog signaling in a tissue-specific manner

The role of compartmentalized signaling in primary cilia during tissue morphogenesis is not well understood. localized G protein-coupled receptor, Gpr161, represses hedgehog pathway via cAMP signaling. We engineered a knock-in at the Gpr161 locus mice to generate variant (Gpr161 mut1 ), which was ciliary localization defective but competent. Tissue phenotypes from depend on downstream bifunctional Gli transcriptional factors functioning as activators or repressors. Compared knockout (ko), mut1/ko had delayed embryonic lethality, moderately increased targets, and partially down-regulated Gli3 repressor. Unlike ko, mut1/ ko neural tube did show Gli2 activator-dependent expansion ventral-most progenitors. Instead, intermediate showed progenitor that depends loss Increased extraciliary receptor levels mut1/mut1 prevented ventralization. Morphogenesis limb buds midface requires repressor; these tissues manifested hyperactivation phenotypes—polydactyly midfacial widening. Thus, pools likely establish tissue-specific repressor thresholds determining morpho-phenotypic outcomes.