Vincent Center of Reproductive Biology, Department of Obstetrics, Gynecology, and Reproductive Biology, Massachusetts General Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States.
Pediatric Surgical Research Laboratories, Department of Surgery, Massachusetts General Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States.
Dev Biol. 2014 Feb 1;386(1):227-36. doi: 10.1016/j.ydbio.2013.12.015. Epub 2013 Dec 19.
A key event during mammalian sexual development is regression of the Müllerian ducts (MDs) in the bipotential urogenital ridges (UGRs) of fetal males, which is caused by the expression of Müllerian inhibiting substance (MIS) in the Sertoli cells of the differentiating testes. The paracrine signaling mechanisms involved in MD regression are not completely understood, particularly since the receptor for MIS, MISR2, is expressed in the mesenchyme surrounding the MD, but regression occurs in both the epithelium and mesenchyme. Microarray analysis comparing MIS signaling competent and Misr2 knockout embryonic UGRs was performed to identify secreted factors that might be important for MIS-mediated regression of the MD. A seven-fold increase in the expression of Wif1, an inhibitor of WNT/β-catenin signaling, was observed in the Misr2-expressing UGRs. Whole mount in situ hybridization of Wif1 revealed a spatial and temporal pattern of expression consistent with Misr2 during the window of MD regression in the mesenchyme surrounding the MD epithelium that was absent in both female UGRs and UGRs knocked out for Misr2. Knockdown of Wif1 expression in male UGRs by Wif1-specific siRNAs beginning on embryonic day 13.5 resulted in MD retention in an organ culture assay, and exposure of female UGRs to added recombinant human MIS induced Wif1 expression in the MD mesenchyme. Knockdown of Wif1 led to increased expression of β-catenin and its downstream targets TCF1/LEF1 in the MD mesenchyme and to decreased apoptosis, resulting in partial to complete retention of the MD. These results strongly suggest that WIF1 secretion by the MD mesenchyme plays a role in MD regression in fetal males.
哺乳动物性发育过程中的一个关键事件是雄性胎儿双潜能尿生殖嵴（UGR）中的缪勒管（MD）退化，这是由分化睾丸中的支持细胞中缪勒抑制物质（MIS）的表达引起的。MD 退化中涉及的旁分泌信号机制尚不完全清楚，特别是因为 MIS 的受体，MISR2，在 MD 周围的间质中表达，但退化发生在上皮细胞和间质中。为了鉴定可能对 MIS 介导的 MD 退化很重要的分泌因子，对 MIS 信号传导有能力和 Misr2 敲除胚胎 UGR 进行了微阵列分析。在表达 Misr2 的 UGR 中观察到 Wif1 的表达增加了七倍，Wif1 是 WNT/β-catenin 信号的抑制剂。Wif1 的整体原位杂交揭示了与 MD 上皮周围间质中的 Misr2 一致的时空表达模式，而在雌性 UGR 和敲除 Misr2 的 UGR 中均不存在。从胚胎第 13.5 天开始，通过 Wif1 特异性 siRNA 对雄性 UGR 中的 Wif1 表达进行敲低导致 MD 在器官培养测定中保留，并且向雌性 UGR 添加重组人 MIS 诱导了 MD 间质中的 Wif1 表达。Wif1 的敲低导致 MD 间质中β-catenin 及其下游靶标 TCF1/LEF1 的表达增加，以及细胞凋亡减少，导致 MD 的部分至完全保留。这些结果强烈表明，MD 间质中 WIF1 的分泌在雄性胎儿的 MD 退化中起作用。
