Expression and characterization of androgen receptor coregulators, SRC-2 and HBO1, during human testis ontogenesis and in androgen signaling deficient patients

Androgen receptor (AR) is essential for testicular physiology and spermatogenesis. SRC-2 and HBO1 are two AR coregulators yet their expression and roles in human testis are unknown. For the first time, we studied by immunohistochemistry and RT-PCR, the expression and distribution of these two coregulators during human testicular ontogenesis, in patients with altered AR signaling (Androgen insensitivity syndrome, AIS) and evaluated the functional impact of SRC-2 and HBO1 on AR signaling in a Sertoli cell context. SRC-2 was present in Sertoli cells at all developmental stages. HBO1 was barely or focally detected in the fetal testis yet its expression, in Sertoli and germ cells, drastically increased postnatally from early infancy to adulthood. In transient co-transfection studies we showed that SRC-2 induced, while HBO1 inhibited AR-mediated transactivation of reporter constructs in murine Sertoli SMAT1 cells. HBO1, but not SRC-2, expression was reduced in testes of patients with AIS compared to normal testes.