Serine Peptidase Inhibitor Kunitz Type 4 (SPINT4)

Spint4 is expressed in the epithelial cells of the distal caput and early corpus. Spint4, and Rnase9 and Rnase10 , while for the ESTs AV381130 and AV381126 no putative functions could be predicted. The expression of Spint4, Rnase9, and AV381130 was found to be under a direct or indirect regulation by androgens, while the expression of Rnase10 is regulated by a testicular factor(s) other than androgen. None of the genes were expressed in the immature epididymis, while mRNAs were detected from d 17 onward, at the time of maturation of epididymal epithelium. However, the expression of AV381130 was not detected until d 30 after birth, indicating a close connection between gene expression and puberty. Spint4 is the only pure Kunitz protease inhibitor so far identified in the epididymis.