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bioRxiv · 10.1101/2020.02.16.951954

The tRNA pseudouridine synthase TruB1 regulates the maturation and function of let-7 miRNA

Kurimoto, R.·Chiba, T.·Ito, Y.·Matsushima, T.·Yano, Y.·Miyata, K.·Suzuki, T.·Tomita, K.·Asahara, H.
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Abstract

Let-7 is an evolutionary conserved microRNA that mediates post-transcriptional gene silencing to regulate a wide range of biological processes, including development, differentiation, and tumor suppression. Let-7 biogenesis is tightly regulated by several RNA-binding proteins, including Lin28A/B, which represses let-7 maturation. To identify new regulators of let-7, we devised a cell-based functional screen of RNA-binding proteins using a let-7 sensor luciferase reporter, and identified the tRNA pseudouridine synthase, TruB1. TruB1 enhanced maturation specifically of let-7 family members. Rather than inducing pseudouridylation of the miRNAs, HITS-CLIP (High throughput sequencing crosslinking immunoprecipitation) and biochemical analyses revealed direct binding between endogenous TruB1 and the stem-loop structure of pri-let-7, which also binds Lin28A/B. TruB1 selectively enhanced the interaction between pri-let-7 and the microprocessor DGCR-8, which mediates miRNA maturation. Finally, TruB1 suppressed cell proliferation, which was mediated in part by let-7. Altogether, we reveal an unexpected function for TruB1 in promoting let-7 maturation and function.

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Kurimoto, R., Chiba, T., Ito, Y., Matsushima, T., Yano, Y., Miyata, K., Suzuki, T., Tomita, K., Asahara, H.. 2020-02-18. The tRNA pseudouridine synthase TruB1 regulates the maturation and function of let-7 miRNA. https://doi.org/10.1101/2020.02.16.951954

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