RASA1 Expression Highlights Z/W Dosage Dynamics and Gonadal Development in Chickens

All identified genes on the avian W chromosome have homologous counterparts on the Z chromosome, with protein-coding genes showing over 90% homology. These W-linked genes have been demonstrated to be dose-sensitive and conserved, thus ensuring a balance in expression between sexes during development.This study explores the sequence characteristics, expression patterns, and potential functions of the RASA1 gene in chicken embryos. In gonads, RASA1-Z was found to be more highly expressed in males, but total mRNA levels (RASA1-C) were higher in females due to RASA1-W compensation. However, RASA1 protein levels were significantly higher in males, suggesting limited contribution of RASA1-W to protein expression. Knockdown of RASA1-Z reduced both mRNA and protein levels, whereas overexpression of RASA1-W increased mRNA but not protein levels. Sex reversal experiments showed no significant changes in RASA1 expression, indicating it is not involved in gonadal sex differentiation. However, higher expression in the left female gonad suggests a role in gonadal development. Functional studies using CCK8 assays revealed that the knockdown of RASA1-Z led to a significant reduction in cell proliferation, while overexpression of RASA1-W had no significant impact on cell proliferation. This study indicates that RASA1 primarily functions in cell proliferation and angiogenesis rather than sex differentiation, with RASA1-W maintaining mRNA homeostasis but contributing minimally to protein levels.