Matoba Shogo, Kanai Yoshiakira, Kidokoro Tomohide, Kanai-Azuma Masami, Kawakami Hayato, Hayashi Yoshihiro, Kurohmaru Masamichi
Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
J Cell Sci. 2005 Apr 1;118(Pt 7):1449-59. doi: 10.1242/jcs.01738. Epub 2005 Mar 15.
Sry is transiently activated in pre-Sertoli cells of the gonadal ridge to initiate testis differentiation in mice. In pre-Sertoli cells, however, the cellular events induced immediately after the onset of Sry expression remain largely unknown. Here we show that testis-specific glycogen accumulation in pre-Sertoli cells is one of the earliest cellular events downstream of Sry action. In developing XY gonads, glycogen accumulation starts to occur in pre-Sertoli cells from around 11.15 dpc (tail somite 14 stage) in a center-to-pole pattern similar to the initial Sry expression profile. Glycogen accumulation was also found in XX male gonads of Sry-transgenic embryos, but not in XX female gonads of wildtype embryos at any developmental stage. In vitro analyses using various culture conditions suggest that testis-specific glycogen deposition is a tissue-autonomous event that can be induced even in serum-free conditions and in a culture of gonadal explants without adjacent mesonephros. Moreover, glycogen accumulation in pre-Sertoli cells was significantly inhibited in vitro by the PI3K inhibitor LY294002, but not by the MEK inhibitor PD98059. Active phospho-AKT (PI3K effector) showed a high degree of accumulation in gonadal somatic cells of genital ridges in a testis-specific manner, both in vitro and in vivo. Therefore, these findings suggest that immediately after the onset of Sry expression, activation of the PI3K-AKT pathway promotes testis-specific glycogen storage in pre-Sertoli cells. To the best of our knowledge, this is a novel Sry-downstream cellular event which preserves this readily available energy source in Sertoli cells for testis-specific morphogenesis and hormone production.
在小鼠性腺嵴的支持细胞前体细胞中，Sry会短暂激活以启动睾丸分化。然而，在支持细胞前体细胞中，Sry表达开始后立即诱导的细胞事件在很大程度上仍不清楚。在这里，我们表明支持细胞前体细胞中睾丸特异性糖原积累是Sry作用下游最早的细胞事件之一。在发育中的XY性腺中，糖原积累从大约11.15 dpc（尾节14期）开始在支持细胞前体细胞中以从中心到两极的模式发生，类似于最初的Sry表达模式。在Sry转基因胚胎的XX雄性性腺中也发现了糖原积累，但在任何发育阶段的野生型胚胎的XX雌性性腺中均未发现。使用各种培养条件的体外分析表明，睾丸特异性糖原沉积是一种组织自主性事件，即使在无血清条件下以及在没有相邻中肾的性腺外植体培养中也可诱导。此外，PI3K抑制剂LY294002在体外可显著抑制支持细胞前体细胞中的糖原积累，但MEK抑制剂PD98059则不能。活性磷酸化AKT（PI3K效应器）在体内外均以睾丸特异性方式在生殖嵴的性腺体细胞中高度积累。因此，这些发现表明，在Sry表达开始后，PI3K-AKT途径的激活促进了支持细胞前体细胞中睾丸特异性糖原的储存。据我们所知，这是一种新的Sry下游细胞事件，它在支持细胞中保留了这种易于利用的能量来源，用于睾丸特异性形态发生和激素产生。
