Sexually Dimorphic MicroRNA Expression During Chicken Embryonic Gonadal Development1

Abstract

MicroRNAs are a highly conserved class of small RNAs that function in a sequence-specific manner to posttranscriptionally regulate gene expression. Tissue-specific miRNA expression studies have discovered numerous functions for miRNAs in various aspects of embryogenesis, but a role for miRNAs in gonadal development and sex differentiation has not yet been reported. Using the chicken embryo as a model, microarrays were used to profile the expression of chicken miRNAs prior to, during, and after the time of gonadal sex differentiation (Embryonic Day 5.5 [E5.5], E6.5, and E9.5). Sexually dimorphic miRNAs were identified, and the expression patterns of several were subjected to further validation by in situ hybridization and Northern blot analysis. Expression of one chicken miRNA, MIR202*, was observed to be sexually dimorphic, with upregulation in the developing testis from the onset of sexual differentiation. Additional data from deep sequencing of male and female embryonic gonad RNA samples also indicated upregulation of MIR202* in male gonads. These findings provide the first evidence of sexually dimorphic miRNA expression during vertebrate gonadal sex differentiation and suggest that MIR202* may function in regulating testicular development.

Sex-biased microRNA expression in mammals and birds reveals underlying regulatory mechanisms and a role in dosage compensation

“…However, from a regulatory perspective, ovary-biased and testis-biased miRNAs may be better described as tissue-biased, since male and female gonads start diverging from a common tissue precursor in early development and have highly distinct transcriptional programs in adulthood (Mank et al 2010;Necsulea et al 2014). To study the regulatory origins of gonadal miRNA expression, a more detailed investigation of sex-biased miRNA expression throughout development would be a useful first step (Bannister et al 2009). …”

“…Even so, previous efforts to identify sex-biased miRNAs in mammals and birds were restricted to a single species and typically also to a single tissue, and many had limited resolution, because they were based on microarray technology and/or lacked biological replicates (Mishima et al 2008;Bannister et al 2009;Cheung et al 2009;Ciaudo et al 2009;Chiang et al 2010;Luo et al 2012;Mujahid et al 2013;Murphy et al 2014;Ziats and Rennert 2014;Kwekel et al 2015Kwekel et al , 2017Link et al 2017). To provide a more complete view of mammalian and avian sex-biased miRNAs, we have conducted the first comprehensive survey of male and female miRNA transcriptomes based on small RNA sequencing of somatic and gonadal tissues from mouse, opossum, and chicken.…”

Role of miR-34c microRNA in the late steps of spermatogenesis

“…The microRNAs, miRNA-372 and miRNA-373, have been implicated as oncogenes in testicular germ cells, but their precise role during spermatogenesis remains elusive (Voorhoeve et al 2006). miRNA expression profiles of various testicular cell populations have been described, and many testicular miRNAs have been isolated (Yu et al 2005;Ro et al 2007;Yan et al 2007;Hayashi et al 2008;Bannister et al 2009;Yan et al 2009). Furthermore, Dicer1, a protein necessary for miRNA processing, and Dnd1, a protein implicated in the protection of mRNAs from miRNAs, are essential for spermatogenesis completion (Kedde et al 2007;Hayashi et al 2008;Maatouk et al 2008).…”

The potential role of microRNAs in regulating gonadal sex differentiation in the chicken embryo

“…MiRNAs are known to regulate cell division and cell fate and identity (reviewed, Pauli et al 2011;Suh and Blelloch 2011). Furthermore, miRNAs have been detected in mammalian and avian gonads during development (Bannister et al 2009;Tripurani et al 2010;Torley et al 2011). Some of these gonadal miRNAs show sexually dimorphic expression patterns and are candidate regulators of sex-specific development.…”