Musashi interaction with poly(A) binding protein is required for activation of target mRNA translation

ABSTRACT: The Musashi family of mRNA translational regulators control both physiological and pathological stem cell self-renewal primarily by repressing targets that promote differentiation. In response to differentiation cues, Musashi can switch from a repressor to an activator of target mRNA translation. However, the molecular events that distinguish Musashi-mediated translational activation from repression are not understood. We have previously reported that Musashi function is required for the maturation of Xenopus oocytes, and specifically for translational activation of specific dormant maternal mRNAs. Here, we employed mass spectrometry to identify cellular factors necessary for Musashi-dependent mRNA translational activation. We report a requirement for association of Musashi1 with the embryonic poly(A) binding protein (ePABP) or the canonical somatic cell poly(A) binding protein PABPC1 for activation of Musashi target mRNA translation. Co-immunoprecipitation studies demonstrated an increased Musashi1 interaction with ePABP during oocyte maturation. Attenuation of endogenous ePABP activity severely compromised Musashi function, preventing downstream signaling and blocking oocyte maturation. Recovery of Musashi-dependent mRNA translational activation and maturation of ePABP attenuated oocytes was achieved through ectopic expression of either ePABP or PABPC1. Consistent with the findings in Xenopus oocytes, PABPC1 remained associated with Musashi under conditions of Musashi target mRNA de-repression and translation during mammalian stem cell differentiation. Since association of Musashi1 with poly(A) binding proteins has previously only been implicated in repression of Musashi target mRNAs, our findings reveal distinct context-dependent roles for the interaction of Musashi with poly[A] binding protein family members in response to extracellular cues that control cell fate.

OTHER RELATED OMICS DATASETS IN: MODEL1109130000 MODEL1311110000 MODEL1909260003 MODEL1311110001 MODEL1909260004 MODEL1703310000 MODEL1909260005 MODEL1909260006

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Xenopus Laevis (african Clawed Frog)

TISSUE(S): Oocyte

SUBMITTER: Stephanie Byrum  

LAB HEAD: Angus M. MacNicol

PROVIDER: PXD013585 | Pride | 2019-05-31

REPOSITORIES: Pride