A RNF12-USP26 amplification loop promotes germ cell specification and is disrupted in urogenital disorders

Ubiquitylation regulates all aspects of development, and components are frequently mutated in developmental disorders. Tonne-Kalscheuer Syndrome (TOKAS) is a X-linked multiple congenital anomaly disorder caused by mutations in the E3 ubiquitin ligase RNF12/RLIM and characterized by intellectual disability and urogenital abnormalities. However, the molecular underpinnings of TOKAS remain largely unknown. Here, we show that RNF12 catalytic activity relieves gene repression to drive a transcriptional program required for germ cell development and priming of pluripotent cells towards the germline. A major feature of the RNF12-dependent gametogenesis gene program is a transcriptional feed-forward loop featuring the deubiquitylase Usp26/USP26. Usp26/USP26 induction stabilises RNF12 to amplify transcriptional responses, which is disrupted by RNF12 TOKAS mutations and USP26 variants identified in patients with fertility defects. In summary, we uncover remarkable synergy within a ubiquitylation cycle that controls expression of key genes required for germ cell development and is disrupted in patients with urogenital abnormalities.