An RNA-binding protein Blanks plays important roles in defining small RNA and mRNA profiles in Drosophila testes

Post-transcriptional regulation of gene expression plays an essential role during oocyte maturation. Here we report that Drosophila MARF1 (Meiosis Regulator And mRNA Stability Factor 1), which consists of one RNA-recognition motif and six tandem LOTUS domains with unknown molecular function, is essential for oocyte maturation. When tethered to a reporter mRNA, MARF1 post-transcriptionally silences reporter expression by shortening reporter mRNA poly-A tail length and thereby reducing reporter protein level. This activity is mediated by the MARF1 LOTUS domain, which binds the CCR4-NOT deadenylase complex. MARF1 binds cyclin A mRNA and shortens its poly-A tail to reduce Cyclin A protein level during oocyte maturation. This study identifies MARF1 as a regulator in oocyte maturation and defines the conserved LOTUS domain as a post-transcriptional effector domain that recruits CCR4-NOT deadenylase complex to shorten target mRNA poly-A tails and suppress their translation.

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“…poly-A+ mRNA libraries were prepared and sequenced on Hiseq4000 as in manufacture protocols (Illumina) 42 , 57 , 58 .…”

Section: Methodsmentioning

confidence: 99%

LOTUS domain protein MARF1 binds CCR4-NOT deadenylase complex to post-transcriptionally regulate gene expression in oocytes

et al. 2018

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“…We noted a detectable drop between the early primer sets (~75% reduction in expression levels compared to controls) and the middle/late primer sets (~95% reduction in expression levels compared to controls), raising the possibility that blanks mutants may have difficulty transcribing this Y-loop gene soon after encountering the first satellite DNA-containing gigantic intron or stabilizing kl-3 transcripts. A recent study that examined global expression changes in blanks mutant testes reported a similar change in kl-3 gene expression [67]. In summary, the RNA-binding protein Blanks localizes to Y-loop B and allows for the robust transcription of the Y-loop B gene kl-3 .…”

Section: Resultsmentioning

confidence: 79%

Satellite DNA-containing gigantic introns in a unique gene expression program during Drosophila spermatogenesis

2019

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Intron gigantism, where genes contain megabase-sized introns, is observed across species, yet little is known about its purpose or regulation. Here we identify a unique gene expression program utilized for the proper expression of genes with intron gigantism. We find that two Drosophila genes with intron gigantism, kl-3 and kl-5 , are transcribed in a spatiotemporal manner over the course of spermatocyte differentiation, which spans ~90 hours. The introns of these genes contain megabases of simple satellite DNA repeats that comprise over 99% of the gene loci, and these satellite-DNA containing introns are transcribed. We identify two RNA-binding proteins that specifically localize to kl-3 and kl-5 transcripts and are needed for the successful transcription or processing of these genes. We propose that genes with intron gigantism require a unique gene expression program, which may serve as a platform to regulate gene expression during cellular differentiation.

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“…Small RNA and mRNA sequencing small RNA and poly(A) + mRNA libraries were prepared and sequenced on Hiseq4000 (Illumina) as previously described (Fukunaga et al 2012;Liao et al 2018;Vakrou et al 2018;Zhu et al 2018b).…”

Section: Qrt-pcrmentioning

confidence: 99%

DEAD-box RNA helicase Belle posttranscriptionally promotes gene expression in an ATPase activity-dependent manner

Liao

Kandasamy

Zhu

et al. 2019

RNA

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Drosophila Belle (human ortholog DDX3) is a conserved DEAD-box RNA helicase implicated in regulating gene expression. However, the molecular mechanisms by which Belle/DDX3 regulates gene expression are poorly understood. Here we performed systematic mutational analysis to determine the contributions of conserved motifs within Belle to its in vivo function. We found that Belle RNA-binding and RNA-unwinding activities and intrinsically disordered regions (IDRs) are required for Belle in vivo function. Expression of Belle ATPase mutants that cannot bind, hydrolyze, or release ATP resulted in dominant toxic phenotypes. Mechanistically, we discovered that Belle up-regulates reporter protein level when tethered to reporter mRNA, without corresponding changes at the mRNA level, indicating that Belle promotes translation of mRNA that it binds. Belle ATPase activity and amino-terminal IDR were required for this translational promotion activity. We also found that ectopic ovary expression of dominant Belle ATPase mutants decreases levels of cyclin proteins, including Cyclin B, without corresponding changes in their mRNA levels. Finally, we found that Belle binds endogenous cyclin B mRNA. We propose that Belle promotes translation of specific target mRNAs, including cyclin B mRNA, in an ATPase activity-dependent manner.

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An RNA-binding protein Blanks plays important roles in defining small RNA and mRNA profiles in Drosophila testes

Cited by 9 publications

References 26 publications

LOTUS domain protein MARF1 binds CCR4-NOT deadenylase complex to post-transcriptionally regulate gene expression in oocytes

LOTUS domain protein MARF1 binds CCR4-NOT deadenylase complex to post-transcriptionally regulate gene expression in oocytes

Satellite DNA-containing gigantic introns in a unique gene expression program during Drosophila spermatogenesis

DEAD-box RNA helicase Belle posttranscriptionally promotes gene expression in an ATPase activity-dependent manner

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