Normal prostatic epithelium depends on androgens for growth, development, secretory function, and survival (1-4). Most remarkably, androgen ablation induces massive apoptosis of prostatic epithelium (2, 5-8). Loss of androgen dependence occurs invariably during prostate carcinogenesis, accounting for poor long term success of androgen ablation therapy (9). Recent studies (10) show that acquisition of androgen autonomy occurs despite retention or elevated expression of the androgen receptor (AR) 1 in the majority of prostate tumors. AR, a 110-kDa zinc finger transcription factor belonging to the nuclear receptor superfamily, is activated by phosphorylation (11) and dimerization upon ligand binding. This promotes nuclear localization and binding of AR to androgenresponsive elements in the promoters of androgen-regulated genes. AR-mediated transcription is regulated by many ARinteracting proteins such as ARA 70 (AR-associated proteins) (12) and ARA 160 (13), along with cAMP-response element-binding protein (14), AP-1 (9, 15), and Ets (16). The growing list of recently discovered AR transcriptional co-regulators supports the notion that complex networks of signals tightly regulate transcription by androgens. Understanding how these signals promote growth and maintain cell viability will certainly impact on the therapeutic strategies for the prevention and cure of prostate cancer.TGF-␤, a potent regulator of cell growth, differentiation, apoptosis, and carcinogenesis in the prostate (17)(18)(19)(20), is under androgenic control. TGF-␤ signals through a cooperative interaction with two cell surface serine/threonine kinase receptors, . TGF-␤ first associates with constitutively active dimeric T␤RII, which then recruits and activates T␤RI kinase by transphosphorylation at a juxtamembrane glycine-serine repeat (21,26). With the help of Smad anchor for receptor activation (27), phosphorylated T␤RI is able to activate Smads 2 and 3 by phosphorylating their carboxyl-terminal serine-serine-Xaa-serine motifs (28). Active Smads 2 and 3 can form heteromeric complexes with co-Smad4, and either directly or through interactions with transcription factors and co-regulators bind to Smad-binding elements (SBEs) in TGF-␤-regulated genes (29 -31). Further activation of Smads 2 and 3 is blocked by Smad7, whose expression is induced upon TGF-␤ stimulation (32).Androgens negatively regulate TGF-␤1 ligand (17, 33) and receptor expression (34,35), along with Smad expression and activation (36) in the prostate. Recent reports show AR associates with Smad3 and that this association may either enhance

MicroRNAs are important regulators of developmental gene expression, but their contribution to fetal gonad development is not well understood. We have identified the evolutionarily conserved gonadal microRNAs miR-202-5p and miR-202-3p as having a potential role in regulating mouse embryonic gonad differentiation. These microRNAs are expressed in a sexually dimorphic pattern as the primordial XY gonad differentiates into a testis, with strong expression in Sertoli cells. In vivo, ectopic expression of pri-miR-202 in XX gonads did not result in molecular changes to the ovarian determination pathway. Expression of the primary transcript of miR-202-5p/3p remained low in XY gonads in a conditional Sox9-null mouse model, suggesting that pri-miR-202 transcription is downstream of SOX9, a transcription factor that is both necessary and sufficient for male sex determination. We identified the pri-miR-202 promoter that is sufficient to drive expression in XY but not XX fetal gonads ex vivo. Mutation of SOX9 and SF1 binding sites reduced ex vivo transactivation of the pri-miR-202 promoter, demonstrating that pri-miR-202 may be a direct transcriptional target of SOX9/SF1 during testis differentiation. Our findings indicate that expression of the conserved gonad microRNA, miR-202-5p/3p, is downstream of the testis-determining factor SOX9, suggesting an early role in testis development.

Normal reproductive function in mammals requires precise control of LH synthesis and secretion by gonadotropes of the anterior pituitary. Synthesis of LH requires expression of two genes [alpha-glycoprotein subunit (alphaGSU) and LHbeta] located on different chromosomes. Hormones from the hypothalamus and gonads modulate transcription of both genes as well as secretion of the biologically active LH heterodimer. In males and females, the transcriptional tone of the genes encoding alphaGSU and LHbeta reflects dynamic integration of a positive signal provided by GnRH from hypothalamic neurons and negative signals emanating from gonadal steroids. Although alphaGSU and LHbeta genes respond transcriptionally in the same manner to changes in hormonal input, different combinations of regulatory elements orchestrate their response. These hormone-responsive regulatory elements are also integral members of much larger combinatorial codes responsible for targeting expression of alphaGSU and LHbeta genes to gonadotropes. In this review, we will profile the genomic landscape of the promoter-regulatory region of both genes, depicting elements and factors that contribute to gonadotrope-specific expression and hormonal regulation. Within this context, we will highlight the different combinatorial codes that control transcriptional responses, particularly those that mediate the opposing effects of GnRH and one of the sex steroids, androgens. We will use this framework to suggest that GnRH and androgens attain the same transcriptional endpoint through combinatorial codes unique to alphaGSU and LHbeta. This parallelism permits the dynamic and coordinate regulation of two genes that encode a single hormone.

Proper cell fate determination in mammalian gonads is critical for the establishment of sexual identity. The Hedgehog (Hh) pathway has been implicated in cell fate decision for various organs, including gonads. Desert Hedgehog (Dhh), one of the three mammalian Hh genes, has been implicated with other genes in the establishment of mouse fetal Leydig cells. To investigate whether Hh alone is sufficient to induce fetal Leydig cell differentiation, we ectopically activated the Hh pathway in Steroidogenic factor 1 (SF1)-positive somatic cell precursors of fetal ovaries. Hh activation transformed SF1-positive somatic ovarian cells into functional fetal Leydig cells. These ectopic fetal Leydig cells produced androgens and insulin-like growth factor 3 (INLS3) that cause virilization of female embryos and ovarian descent. However, the female reproductive system remained intact, indicating a typical example of female pseudohermaphroditism. The appearance of fetal Leydig cells was a direct consequence of Hh activation as evident by the absence of other testicular components in the affected ovary. This study provides not only insights into mechanisms of cell lineage specification in gonads, but also a model to understand defects in sexual differentiation.

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