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Sex-biased expression of microRNAs in Drosophila melanogaster.

Marco A - Open Biol (2014)

Bottom Line: As with protein-coding genes, sex-biased microRNAs are associated with the reproductive function.MicroRNAs with sex-biased expression do not preferentially target sex-biased gene transcripts.These results strongly suggest that the sex-biased expression of microRNAs is mainly a consequence of high rates of microRNA emergence in the X chromosome (male bias) or hitchhiked expression by host genes (female bias).

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK.

ABSTRACT
Most animals have separate sexes. The differential expression of gene products, in particular that of gene regulators, is underlying sexual dimorphism. Analyses of sex-biased expression have focused mostly on protein-coding genes. Several lines of evidence indicate that microRNAs, a class of major gene regulators, are likely to have a significant role in sexual dimorphism. This role has not been systematically explored so far. Here, I study the sex-biased expression pattern of microRNAs in the model species Drosophila melanogaster. As with protein-coding genes, sex-biased microRNAs are associated with the reproductive function. Strikingly, contrary to protein-coding genes, male-biased microRNAs are enriched in the X chromosome, whereas female microRNAs are mostly autosomal. I propose that the chromosomal distribution is a consequence of high rates of de novo emergence, and a preference for new microRNAs to be expressed in the testis. I also suggest that demasculinization of the X chromosome may not affect microRNAs. Interestingly, female-biased microRNAs are often encoded within protein-coding genes that are also expressed in females. MicroRNAs with sex-biased expression do not preferentially target sex-biased gene transcripts. These results strongly suggest that the sex-biased expression of microRNAs is mainly a consequence of high rates of microRNA emergence in the X chromosome (male bias) or hitchhiked expression by host genes (female bias).

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Expression profile of sex-biased microRNAs. Hierarchical clustering and heatmap of microRNAs with sex-biased expression. Z-scores were scaled across rows. Green colour indicates an overexpression in a given tissue/sample with respect to the other samples (columns). SSC, somatic stem cells.
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RSOB140024F2: Expression profile of sex-biased microRNAs. Hierarchical clustering and heatmap of microRNAs with sex-biased expression. Z-scores were scaled across rows. Green colour indicates an overexpression in a given tissue/sample with respect to the other samples (columns). SSC, somatic stem cells.

Mentions: To further understand what it means to be sex-biased expressed, the expression profile of biased microRNAs was explored. Figure 2 plots a hierarchical tree of sex-biased expressed microRNAs and their relative expression levels in testes, ovaries and early embryos. Most male-biased microRNAs are highly expressed in the testes. This indicates that production of microRNAs in males is largely associated with the germline and the reproduction function. This is consistent with figure 1a in which adult samples were poorly correlated with young samples, perhaps because young individuals have not yet developed fully functional gonads.Figure 2.


Sex-biased expression of microRNAs in Drosophila melanogaster.

Marco A - Open Biol (2014)

Expression profile of sex-biased microRNAs. Hierarchical clustering and heatmap of microRNAs with sex-biased expression. Z-scores were scaled across rows. Green colour indicates an overexpression in a given tissue/sample with respect to the other samples (columns). SSC, somatic stem cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043116&req=5

RSOB140024F2: Expression profile of sex-biased microRNAs. Hierarchical clustering and heatmap of microRNAs with sex-biased expression. Z-scores were scaled across rows. Green colour indicates an overexpression in a given tissue/sample with respect to the other samples (columns). SSC, somatic stem cells.
Mentions: To further understand what it means to be sex-biased expressed, the expression profile of biased microRNAs was explored. Figure 2 plots a hierarchical tree of sex-biased expressed microRNAs and their relative expression levels in testes, ovaries and early embryos. Most male-biased microRNAs are highly expressed in the testes. This indicates that production of microRNAs in males is largely associated with the germline and the reproduction function. This is consistent with figure 1a in which adult samples were poorly correlated with young samples, perhaps because young individuals have not yet developed fully functional gonads.Figure 2.

Bottom Line: As with protein-coding genes, sex-biased microRNAs are associated with the reproductive function.MicroRNAs with sex-biased expression do not preferentially target sex-biased gene transcripts.These results strongly suggest that the sex-biased expression of microRNAs is mainly a consequence of high rates of microRNA emergence in the X chromosome (male bias) or hitchhiked expression by host genes (female bias).

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK.

ABSTRACT
Most animals have separate sexes. The differential expression of gene products, in particular that of gene regulators, is underlying sexual dimorphism. Analyses of sex-biased expression have focused mostly on protein-coding genes. Several lines of evidence indicate that microRNAs, a class of major gene regulators, are likely to have a significant role in sexual dimorphism. This role has not been systematically explored so far. Here, I study the sex-biased expression pattern of microRNAs in the model species Drosophila melanogaster. As with protein-coding genes, sex-biased microRNAs are associated with the reproductive function. Strikingly, contrary to protein-coding genes, male-biased microRNAs are enriched in the X chromosome, whereas female microRNAs are mostly autosomal. I propose that the chromosomal distribution is a consequence of high rates of de novo emergence, and a preference for new microRNAs to be expressed in the testis. I also suggest that demasculinization of the X chromosome may not affect microRNAs. Interestingly, female-biased microRNAs are often encoded within protein-coding genes that are also expressed in females. MicroRNAs with sex-biased expression do not preferentially target sex-biased gene transcripts. These results strongly suggest that the sex-biased expression of microRNAs is mainly a consequence of high rates of microRNA emergence in the X chromosome (male bias) or hitchhiked expression by host genes (female bias).

Show MeSH
Related in: MedlinePlus