アクティブボード・２００９年　７月
　　　　　・・・・・２００９年　７月　３日更新・・・・・

研究発表を行った学会；
・42nd Annual Meeting for the Japanese Society of Developmental Biologists.
　２００９年　５月２８日〜３１日（新潟）

タイトル；Six1 and Six4 homeoproteins are required for
sex determination in mice gonad.
.
　
発表者；　藤本　由佳　氏
　　　（熊本大学　発生医学研究所　腎臓発生分野）
Abstract；
Six family genes are mammalian homolog of Drosophila sine oculis, which encodes a transcriptional factor with characteristic homeo-domain and six-domain. We previously reported the cooperative functions of Six1 and Six4 are essential for the kidney formation by analyzing Six1/Six4-deficient mice, whereas Six4-deficient mice have no apparent abnormality. We here reported that the cooperative functions of Six1 and Six4 in the sex determination that male to female sex-reversal was found in the Six1/Six4-deficient gonads due to the impaired Sry and Sox9 expression.
In the E18.5 XY-mutant gonads, expression of male-specific marker genes (Mis, 3βHSD, Sox9) expression was deceased or absent, and germ cells entered into the meiotic division, which was never observed in the XY-wild type gonads, suggesting that the XY-mutant gonad is functionally equivalent to the female gonad. On E11.5, when sex-determination gene Sry expression reaches a peak, Sry and subsequent Sox9 expression were down-regulated in the XY-mutant gonads. We also found that E11.5 mutant genital ridges were smaller than the wild-type in both sexes, and the numbers of SF1/Ad4BP positive genital ridge precursor cells were reduced in E10.5 mutant genital ridge, suggesting that Six1 and Six4 might be required for the generation of the SF1/Ad4BP positive precursor cells and subsequent Sry expression. Our findings highlight the potential functions of Six1 and Six4 in the sex determination.