The E3 ubiquitin ligase RNF12 plays essential roles during development, and the gene encoding it, RLIM, is mutated in the X-linked human developmental disorder Tonne-Kalscheuer syndrome (TOKAS). Substrates of RNF12 include transcriptional regulators such as the pluripotency-associated transcriptional repressor REX1. Using global quantitative proteomics in male mouse embryonic stem cells, we identified the deubiquitylase USP26 as a putative downstream target of RNF12 activity. RNF12 relieved REX1-mediated repression of Usp26, leading to an increase in USP26 abundance and the formation of RNF12-USP26 complexes. Interaction with USP26 prevented RNF12 autoubiquitylation and proteasomal degradation, thereby establishing a transcriptional feed-forward loop that amplified RNF12-dependent derepression of REX1 targets. We showed that the RNF12-USP26 axis operated specifically in mouse testes and was required for the expression of gametogenesis genes and for germ cell differentiation in vitro. Furthermore, this RNF12-USP26 axis was disrupted by RLIM and USP26 variants found in TOKAS and infertility patients, respectively. This work reveals synergy within the ubiquitylation cycle that controls a key developmental process in gametogenesis and that is disrupted in human genetic disorders.
Nota bibliográficaFunding Information:
We thank W. Reik and J. Spindel (Babraham Institute) and V. Cowling (University of Dundee) for helpful discussions and V. Cowling and J. Silva (University of Dundee) for mouse tissue extracts.G.M.F. and F.B. were supported by a Wellcome Trust/Royal Society Sir Henry Dale Fellowship (211209/Z/18/Z) and a Medical Research Council New Investigator Award (MR/N000609/1). A.S.-F. was supported by a MRC-PPU prize studentship. C.E.-S. was supported by a Wellcome Trust PhD studentship. H.Z. was supported by the MRC-PPU core grant. G.N. was supported by ANID/CONICYT–FONDECYT de Iniciación 11190998 and ANID–Basal funding for Scientific and Technological Center of Excellence, IMPACT, FB210024. I.B. was supported by NIH grant GM128168.
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