Preliminary Study on Expression and Function of the Chicken W Chromosome Gene MIER3 in Embryonic Gonads.

The sex chromosomes of birds are designated Z and W. The male is homogamous (ZZ), and the female is heterogamous (ZW). The chicken W chromosome is a degenerate version of the Z chromosome and harbors only 28 protein-coding genes. We studied the expression pattern of the W chromosome gene (showing differential expression during gonadogenesis) in chicken embryonic gonads and its potential role in gonadal development. The W copy of () shows a gonad-biased expression in chicken embryonic tissues which was different from its Z copy. The overall expression of and mRNA and protein is correlated with the gonadal phenotype being higher in female gonads than in male gonads or female-to-male sex-reversed gonads. Chicken MIER3 protein is highly expressed in the nucleus, with relatively lower expression in the cytoplasm. Overexpression of in male gonad cells suggested its effect on the GnRH signaling pathway, cell proliferation, and cell apoptosis. expression is associated with the gonadal phenotype. may promote female gonadal development by regulating and genes. These findings enrich our knowledge of chicken W chromosome genes and support a more systematic and in-depth understanding of gonadal development in chickens.