Paracrine role of MIS in Steroidogenesis

MIS是生长和分化因子tgf β家族中的一种糖蛋白，其在胎儿缪勒管退化中的作用对正常男性性发育至关重要。人类的支持细胞在妊娠7周开始产生MIS，这是早期SRY启动的睾丸成熟步骤的结果。MIS的产生在两性中持续到成年，这可能是其作为成人性腺功能调节器作用的基础。过表达MIS的成年转基因小鼠出现严重的性腺异常，包括间质细胞发育不全、睾酮水平降低和生育能力低下。没有MIS或II型受体的小鼠表现出相反的表型，显示出间质细胞增生和睾酮水平升高。该实验室先前的实验表明，MIS在转录水平上抑制睾酮的产生，也可能通过抑制裂解酶步骤来实现这一点。为了更好地描述裂解酶抑制的机制，我计划使用病毒启动子驱动的P450c17基因来研究MIS的作用，我还计划研究MIS对P450c17酶磷酸化状态的影响，P450c17酶是裂解酶活性的潜在调节因子。最后，我将使用重组人MIS和MA-10细胞进行基因阵列实验。这一努力的结果将使我开始研究参与MIS信号和雄激素合成的分子途径。

MIS is a glycoprotein in the TGFbeta family of Growth and differentiation factors whose role in fetal Mullerian regression is critical to normal male sexual development. The Sertoli cells begin producing MIS in humans at 7 weeks gestation as a result of the earlier SRY initiated testicular maturational steps. MIS production continues into adulthood in both sexes, which may underlie its role as a regulator of adult gonadal function. Adult transgenic mice over expressing MIS develop severe gonadal abnormalities including Leydig cell hypoplasia, lowered testosterone levels, and subfertility. Mice that are null for MIS or the type II receptor develop the opposite phenotype, showing Leydig cell hyperplasia and elevated testosterone levels. Previous experiments by this lab have shown that MIS inhibits testosterone production at the transcriptional level and may also do this by inhibition of the lyase step. To better delineate the mechanism's of the lyase suppression I plan to investigate MIS's effect using a viral-promoter driven P450c17 gene, and I also plan to examine MIS's effect on the phosphorylation state of the P450c17 enzyme, a potential regulatory of lyase activity. Finally I will perform gene array experiments using recombinant human MIS and MA-10 cells. The results of this effort will allow me to begin to study the molecular pathways involved in MIS signaling and androgen synthesis.