The Nab2 RNA binding protein promotes sex-specific splicing of Sex lethal in Drosophila neuronal tissue
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PROVIDER: PRJNA682171 | ENA |
REPOSITORIES: ENA
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Project description:The Drosophila polyadenosine RNA binding protein Nab2, which is orthologous to a human protein lost in a form of inherited intellectual disability, controls axon projection, locomotion, and memory. Here we define an unexpectedly specific role for Nab2 in regulating splicing of ~150 exons/introns in the head transcriptome and link the most prominent of these, female retention of a male-specific exon in the sex determination factor Sex-lethal (Sxl), to a role in m6A-dependent mRNA splicing. Genetic evidence indicates that aberrant Sxl splicing underlies multiple phenotypes in Nab2 mutant females. At a molecular level, Nab2 associates with Sxl pre-mRNA and ensures proper female-specific splicing by preventing m6A hypermethylation by Mettl3 methyltransferase. Consistent with these results, reducing Mettl3 expression rescues developmental, behavioral and neuroanatomical phenotypes in Nab2 mutants. Overall these data identify Nab2 as a required regulator of m6A-regulated Sxl splicing and imply a broader link between Nab2 and Mettl3-regulated brain RNAs.
2020-12-02 | GSE162531 | GEO
Project description:Nab2 encodes a polyadenosine RNA-binding protein (RBP) with broad roles in post-transcriptional regulation, including in RNA export, poly(A) tail length control, and mRNA splicing, and loss of its human ortholog ZC3H14 gives rise to a form of autosomal recessive intellectual disability. Understanding of Nab2/ZC3H14 function in metazoan nervous systems is limited, in part, because no comprehensive identification of metazoan-Nab2-associated RNA transcripts has yet been conducted. Moreover, many Nab2/ZC3H14 functional protein partnerships likely remain unidentified. Here we present evidence that Drosophila melanogaster Nab2 interacts with the RBP Ataxin-2 (Atx2), a neuronal translational regulator, and implicate these proteins in coordinate regulation of neuronal morphology and adult viability. We then present the first high-throughput identifications of RNAs associating with Nab2 and Atx2 in Drosophila brain neurons using an RNA immunoprecipitation-sequencing (RIP-Seq) approach. Critically, the RNA interactomes of each RBP overlap. The identities of shared associated transcripts (e.g. drk, me31B, stai) and of transcripts specific to Nab2 or Atx2 (e.g. Arpc2, tea, respectively) promise insight into the neuronal functions of and interactions between each RBP. Significantly, we find Nab2 exhibits high specificity in its RNA associations in neurons in vivo, associating with only a fraction of all polyadenylated RNAs. These Nab2-associated RNAs are overrepresented for internal A-rich motifs, suggesting such sequences may partially mediate Nab2 target selection. Taken together, these data demonstrate 1)Nab2 opposingly regulates neuronal morphology and shares associated neuronal RNAs with Atx2 and 2)Drosophila Nab2 associates with a more specific subset of polyadenylated mRNAs than its polyadenosine affinity alone may suggest.
2021-02-05 | GSE165677 | GEO
Project description:Conversely to canonical splicing, back-splicing covalently ligates the upstream 3' splice site (SS) with downstream 5'SS and generates exonic circular RNAs (circRNAs) that are widely-identified in eukaryotes and have regulatory functions in gene expression. However, sex-specific back-splicing in Drosophila has not been investigated and its regulation remains unclear. Here, we performed multiple RNA-seq of various sex-specific Drosophila samples including head, body and gonads from both genders, and identified more than ten thousand of circular RNAs, in which hundreds are sex-differentially expressed and back-spliced. Intriguingly, we found that expression of SXL, an RNA-binding protein encoded by Sex-lethal (Sxl), the master Drosophila sex-determination gene which only functionally spliced in females, promotes back-splicing of many female-differentially expressed circRNAs in the male S2 cells, while expression of a SXL mutant did not. Using a monoclonal antibody, we further obtained the transcriptome-wide RNA-binding sites of SXL through a PAR-CLIP approach and revealed that SXL-binding on flanking exons and introns of pre-mRNAs facilitates back-splicing of those circRNAs, whereas SXL-binding on the circRNA exons inhibits the back-splicing. This study provides strong evidence that SXL has a regulatory role in back-splicing to generate sex-specifc circRNAs, as well as in the initiation of Drosophila sex-determination cascade through canoncial forward-splicing.
2023-04-23 | GSE221102 | GEO
Project description:In Drosophila female development is governed by a single RNA-binding protein, Sex lethal (Sxl), that controls the expression of key factors involved in dosage compensation, germline homeostasis and the establishment of female morphology and behaviour. Functional Sxl protein is only synthesized in female flies. Its expression is established in the pre-cellular, female embryo by an X-chromosome counting mechanism and maintained by a positive feedback loop with Sxl controlling alternative splicing of its own transcript. In male flies this feedback loop is not activated, keeping Sxl expression in the ‘off’ state. But what protects males against accidental triggering of the self-sustaining feedback loop and Sxl protein production snowballing out of control? Here we identify Sister of sex lethal (Ssx) as a protein that antagonizes Sxl in autoregulatory splicing by competition for the same RNA elements. Male flies mutant for ssx exhibit a low level of productive Sxl mRNA splicing and in cultured Drosophila cells, Sxl-induced changes in alternative splicing can be reverted by the expression of Ssx. In sum, this demonstrates that Ssx helps to establish a stable, male-specific gene expression pattern by protecting male flies against triggering Sxl expression.
2019-01-15 | GSE98188 | GEO
Project description:In Drosophila female development is governed by a single RNA-binding protein, Sex lethal (Sxl), that controls the expression of key factors involved in dosage compensation, germline homeostasis and the establishment of female morphology and behaviour. Functional Sxl protein is only synthesized in female flies. Its expression is established in the pre-cellular, female embryo by an X-chromosome counting mechanism and maintained by a positive feedback loop with Sxl controlling alternative splicing of its own transcript. In male flies this feedback loop is not activated, keeping Sxl expression in the ‘off’ state. But what protects males against accidental triggering of the self-sustaining feedback loop and Sxl protein production snowballing out of control? Here we identify Sister of sex lethal (Ssx) as a protein that antagonizes Sxl in autoregulatory splicing by competition for the same RNA elements. Male flies mutant for ssx exhibit a low level of productive Sxl mRNA splicing and in cultured Drosophila cells, Sxl-induced changes in alternative splicing can be reverted by the expression of Ssx. In sum, this demonstrates that Ssx helps to establish a stable, male-specific gene expression pattern by protecting male flies against triggering Sxl expression.
2019-01-15 | GSE98187 | GEO
Project description:Nascent RNA sequencing has recently revealed that pre-mRNA splicing can occur shortly after the intron emerges from RNA polymerase II (Pol II). Differences in co-transcriptional splicing profiles suggest regulation by cis- and/or trans-acting factors. Here we used Single Molecule Intron Tracking (SMIT) in budding yeast to identify a cohort of regulators by machine learning. One candidate, Nab2, displayed reduced co-transcriptional splicing of some pre-mRNAs when depleted. Unexpectedly, these splicing defects were attributable to readthrough transcription, which was revealed by long read sequencing of nascent RNA; individual readthrough transcripts induced by Nab2 depletion sometimes spanned multiple genes. Thus, Nab2 regulation of splicing was indirect. Moreover, unspliced transcripts displayed downstream readthrough in both control and Nab2-depleted cells, highlighting the coupling between splicing and 3′ end formation. We conclude that Nab2 is required for proper 3′ end processing, which ensures both transcription termination as well as proper splicing of downstream genes.
2020-10-27 | GSE156133 | GEO
Project description:Flipping the switch on Sex-lethal expression: Sister of Sex-lethal antagonizes Sxl-dependent alternative splicing to maintain a male-specific gene expression pattern in Drosophila
| PRJNA384219 | ENA
Project description:Gene expression in eukaryotes is an essential process that includes transcription, pre-RNA processing and RNA export. All these steps are coupled and normally, any failure in one step affects the other steps and could cause nuclear mRNA retention. One important player in this interface is the poly(A)-RNA binding protein Nab2, which regulates the poly(A)-tail length of mRNAs protecting their 3’-ends from a second round of polyadenylation and facilitating their nucleo-cytoplasmic export. Interestingly, here we show that Nab2 has additional roles in mRNA transcription elongation, tRNA metabolism and rRNA export. We use Genome-wide analysis of expression of a conditional degron nab2 mutant that allows the depletion of the protein in 15 minutes, to demosntrate that the role of Nab2 in RNAPII transcription and RNAPIII metabolism is not the result of a secondary effect. Our results identify primary targets of nab2 revealing novel functions for Nab2 in transcription and metabolism of most types of RNAs, not only poly(A) mRNAs, indicating that Nab2 function is more ubiquitous than previously anticipated, being a central player in the general and coordinated control of gene expression from transcription elongation to translation initiation.
2011-12-01 | GSE19302 | GEO
Project description:Gene expression in eukaryotes is an essential process that includes transcription, pre-RNA processing and RNA export. All these steps are coupled and normally, any failure in one step affects the other steps and could cause nuclear mRNA retention. One important player in this interface is the poly(A)-RNA binding protein Nab2, which regulates the poly(A)-tail length of mRNAs protecting their 3M-bM-^@M-^Y-ends from a second round of polyadenylation and facilitating their nucleo-cytoplasmic export. Interestingly, here we show that Nab2 has additional roles in mRNA transcription elongation, tRNA metabolism and rRNA export. We use Genome-wide analysis of expression of nab2-1 mutant to demosntrate that the role of Nab2 in RNAPII transcription and RNAPIII metabolism is not the result of a secondary effect. Our results identify primary targets of nab2 revealing novel functions for Nab2 in transcription and metabolism of most types of RNAs, not only poly(A) mRNAs, indicating that Nab2 function is more ubiquitous than previously anticipated, being a central player in the general and coordinated control of gene expression from transcription elongation to translation initiation. Three repeats of the wild type and nab2-1 mutant
2011-12-01 | E-GEOD-26303 | biostudies-arrayexpress
Project description:Gene expression in eukaryotes is an essential process that includes transcription, pre-RNA processing and RNA export. All these steps are coupled and normally, any failure in one step affects the other steps and could cause nuclear mRNA retention. One important player in this interface is the poly(A)-RNA binding protein Nab2, which regulates the poly(A)-tail length of mRNAs protecting their 3’-ends from a second round of polyadenylation and facilitating their nucleo-cytoplasmic export. Interestingly, here we show that Nab2 has additional roles in mRNA transcription elongation, tRNA metabolism and rRNA export. We use Genome-wide analysis of expression of nab2-1 mutant to demosntrate that the role of Nab2 in RNAPII transcription and RNAPIII metabolism is not the result of a secondary effect. Our results identify primary targets of nab2 revealing novel functions for Nab2 in transcription and metabolism of most types of RNAs, not only poly(A) mRNAs, indicating that Nab2 function is more ubiquitous than previously anticipated, being a central player in the general and coordinated control of gene expression from transcription elongation to translation initiation.
2011-12-01 | GSE26303 | GEO