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Updated: May 2, 2026
Xenopus laevis as a Model to Identify Translation Impairment
Published on: September 27, 2015
Musashi protein-directed translational activation of target mRNAs is mediated by the poly(A) polymerase, germ line
Chad Cragle1, Angus M MacNicol2
1From the Interdiciplinary Biomedical Sciences, Departments of Neurobiology and Developmental Sciences.
Abstract:
The mRNA-binding protein, Musashi, has been shown to regulate translation of select mRNAs and to control cellular identity in both stem cells and cancer cells. Within the mammalian cells, Musashi has traditionally been characterized as a repressor of translation. However, we have demonstrated that Musashi is an activator of translation in progesterone-stimulated oocytes of the frog Xenopus laevis, and recent evidence has revealed Musashi's capability to function as an activator of translation in mammalian systems. The molecular mechanism by which Musashi directs activation of target mRNAs has not been elucidated. Here, we report a specific association of Musashi with the noncanonical poly(A) polymerase germ line development defective-2 (GLD2) and map the association domain to 31 amino acids within the C-terminal domain of Musashi. We show that loss of GLD2 interaction through deletion of the binding domain or treatment with antisense oligonucleotides compromises Musashi function. Additionally, we demonstrate that overexpression of both Musashi and GLD2 significantly enhances Musashi function. Finally, we report a similar co-association also occurs between murine Musashi and GLD2 orthologs, suggesting that coupling of Musashi to the polyadenylation apparatus is a conserved mechanism to promote target mRNA translation.
Insights
Musashi protein activates mRNA translation, a function previously thought to be repressive. This study reveals Musashi partners with GLD2, a poly(A) polymerase, to enhance translation, a conserved mechanism across species.
Area of Science:
- Molecular Biology
- Developmental Biology
- Cell Biology
Background:
- Musashi (MSI) is an mRNA-binding protein regulating translation and cellular identity.
- MSI is traditionally viewed as a translational repressor in mammals.
- Recent findings suggest MSI can activate translation in certain contexts.
Purpose of the Study:
- To elucidate the molecular mechanism of MSI-mediated translational activation.
- To investigate the interaction between MSI and other regulatory proteins.
- To determine if this mechanism is conserved.
Main Methods:
- Co-immunoprecipitation to detect protein-protein interactions.
- Mapping of the MSI-GLD2 interaction domain using deletion mutants.
- Antisense oligonucleotide treatment to inhibit GLD2.
- Overexpression studies of MSI and GLD2.
- Comparative analysis with murine orthologs.
Main Results:
- Identified a specific association between Musashi and germ line development defective-2 (GLD2), a noncanonical poly(A) polymerase.
- Mapped the interaction domain to a 31-amino acid region in Musashi's C-terminus.
- Disruption of the MSI-GLD2 interaction impaired Musashi function.
- Overexpression of both MSI and GLD2 synergistically enhanced MSI's translational activation.
- Confirmed a similar association between murine Musashi and GLD2.
Conclusions:
- Musashi functions as a translational activator, contrary to its traditional role.
- The interaction with GLD2 is crucial for Musashi's activation function.
- Coupling Musashi to the polyadenylation machinery via GLD2 is a conserved mechanism for promoting target mRNA translation.
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