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PMID:29635389

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Citation

Szostak, E, García-Beyaert, M, Guitart, T, Graindorge, A, Coll, O and Gebauer, F' (2018) Hrp48 and eIF3d contribute to msl-2 mRNA translational repression. Nucleic Acids Res. '

Abstract

Translational repression of msl-2 mRNA in females of Drosophila melanogaster is an essential step in the regulation of X-chromosome dosage compensation. Repression is orchestrated by Sex-lethal (SXL), which binds to both untranslated regions (UTRs) of msl-2 and inhibits translation initiation by poorly understood mechanisms. Here we identify Hrp48 as a SXL co-factor. Hrp48 binds to the 3' UTR of msl-2 and is required for optimal repression by SXL. Hrp48 interacts with eIF3d, a subunit of the eIF3 translation initiation complex. Reporter and RNA chromatography assays showed that eIF3d binds to msl-2 5' UTR, and is required for efficient translation and translational repression of msl-2 mRNA. In line with these results, eIF3d depletion -but not depletion of other eIF3 subunits- de-represses msl-2 expression in female flies. These data are consistent with a model where Hrp48 inhibits msl-2 translation by targeting eIF3d. Our results uncover an important step in the mechanism of msl-2 translation regulation, and illustrate how general translation initiation factors can be co-opted by RNA binding proteins to achieve mRNA-specific control.

Links

PubMed Online version:10.1093/nar/gky246

Keywords


Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

DROME:EI3D1

GO:0003743: translation initiation factor activity

ECO:0000315:

F

Depletion of eIF3d from SL2 cells reduced translation of an msl-2 reporter, while depletion of other subunits (eIF3e, eIF3h) had no effect (Figure 5DE)

complete
CACAO 13244

DROME:RB27C

GO:0030371: translation repressor activity

ECO:0000315:

F

They depleted Hrp48 from SL2 cells and tested the ability of exogenous SXL to inhibit the translation of a reporter containing full-length msl-2 5′ and 3′ UTRs (Figure 3A). Depletion of Hrp48 indeed reduced the capacity of SXL to inhibit translation of the reporter (Figure 3B). The results of this paper support a model where a repressor complex composed of SXL, UNR and Hrp48 assembles at the 3′ UTR of msl-2 mRNA; Hrp48 then contributes to inhibit ribosome recruitment by targeting eIF3d.(Figure 8)

complete
CACAO 13242

Notes

See also

References

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