RESUMO
Ribosomes are regulated by evolutionarily conserved ubiquitination/deubiquitination events. We uncover the role of the deubiquitinase OTUD6 in regulating global protein translation through deubiquitination of the RPS7/eS7 subunit on the free 40 S ribosome in vivo in Drosophila. Coimmunoprecipitation and enrichment of monoubiquitinated proteins from catalytically inactive OTUD6 flies reveal RPS7 as the ribosomal substrate. The 40 S protein RACK1 and E3 ligases CNOT4 and RNF10 function upstream of OTUD6 to regulate alkylation stress. OTUD6 interacts with RPS7 specifically on the free 40 S, and not on 43 S/48 S initiation complexes or the translating ribosome. Global protein translation levels are bidirectionally regulated by OTUD6 protein abundance. OTUD6 protein abundance is physiologically regulated in aging and in response to translational and alkylation stress. Thus, OTUD6 may promote translation initiation, the rate limiting step in protein translation, by titering the amount of 40 S ribosome that recycles.
Assuntos
Proteínas de Drosophila , Biossíntese de Proteínas , Proteínas Ribossômicas , Ubiquitinação , Animais , Proteínas Ribossômicas/metabolismo , Proteínas Ribossômicas/genética , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Ribossomos/metabolismo , Estresse Fisiológico , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genéticaRESUMO
Mutations in the hedgehog (Hh) signaling are implicated in birth defects and cancers, including medulloblastoma (MB), one of the most malignant pediatric brain tumors. Current Hh inhibitors face the challenge of drug resistance and tumor relapse, urging new insights in the Hh pathway regulation. Our previous study revealed how PDE4D controls global levels of cAMP in the cytoplasm to positively regulate Hh signaling; in the present study, we found that a specific isoform PDE4D3 is tethered to the centrosome by Myomegalin (Mmg), a centrosome/Golgi-associated protein. Mmg loss dislocates PDE4D3 from the centrosome, leading to local PKA overactivation and inhibition of the Hh signaling, leaving other PKA-related pathways unaffected. Mmg loss suppresses the proliferation of granule neuron precursors and blocks the growth of MB in mouse model. Our findings specify a new regulatory mechanism of the Hh pathway and highlight an exciting therapeutic avenue for Hh-related cancers with reduced side effects.