Practice question

Sry gene on Y chromosome encodes HMG-box transcription factor transiently expressed in XY genital ridges between 10.5-12.5 days in mice. Protein binds with Sf1 and Wt1 to testis-specific enhancer element TESCO upstream of Sox9, causing chromatin bending, recruitment of coactivators and dramatic Sox9 transcriptional upregulation. Immediate induction commits pre-supporting cells to Sertoli lineage, initiating Amh expression, testis cord morphogenesis and repression of ovarian genes. No other autosomal genes are directly activated by Sry in this manner; Wnt4 and Foxl2 lie in opposing pathway actively suppressed following Sox9 induction.