The Role of MAP3K1 in the Development of the Female Reproductive Tracts. The Role of MAP3K1 in the Development of the Female Reproductive Tracts

Mitogen-Activated Protein 3 Kinase 1 (MAP3K1) is a dynamic signaling molecule with myriad cell-type specific functions not yet fully understood. Here we describe a role of MAP3K1 in the development of female reproductive tract (FRT). MAP3K1 kinase domain deficient females (Map3k1ΔKD) exhibit imperforate vagina, labor failure and sterility. The defects correspond to shunted Müllerian duct (MD), precursor of the FRT, in embryos, and contorted caudal vagina and abrogated vagina-urogenital sinus fusion in newborns. Although MAP3K1 acts through JNK and ERK to activate WNT in epithelial cells, it is dispensable for epithelial but crucial for mesenchymal WNT activity at the caudal embryonic MD in vivo. Moreover, conditional media derived from MAP3K1-compentent, but not -deficient, epithelial cells activate TCF-luciferase reporter in fibroblasts, suggesting MAP3K1 induces secreted activators from epithelial cells to activate WNT in fibroblasts. Correspondingly, the expression of Wnt7b is high in wild type, but low in Map3k1 knockout caudal MD epithelium and MAP3K1-deficient keratinocytes. Our data reveal a temporal-spatial paracrine MAP3K1-WNT crosstalk in the regulation of caudal MD elongation and FRT development. Overall design: Three independent samples of human epithelial HaCaT cells genetically-modified to have increased (SAM) MAP3K1 expression were compared to three independent samples of human epithelial HaCaT cells genetically-modified to have decreased (shRNA) MAP3K1 expression.

丝裂原活化蛋白激酶3激酶1（Mitogen-Activated Protein 3 Kinase 1，MAP3K1）是一种动态信号分子，具备众多尚未完全阐明的细胞类型特异性功能。本研究阐述了MAP3K1在雌性生殖道（female reproductive tract，FRT）发育中的作用。MAP3K1激酶结构域缺陷雌性小鼠（Map3k1ΔKD）表现出阴道闭锁、分娩失败与不育表型。上述缺陷对应胚胎时期米勒管（Müllerian duct，MD，雌性生殖道的前体）出现异常分流，以及新生小鼠的尾段阴道扭曲与阴道-尿生殖窦融合受阻。尽管MAP3K1可通过JNK与ERK通路激活上皮细胞内的WNT信号，但在体内尾段胚胎米勒管中，其对上皮细胞的WNT活性并非必需，却对间充质细胞的WNT活性至关重要。此外，源自携带功能完整型MAP3K1的上皮细胞（而非缺陷型MAP3K1上皮细胞）的条件培养基，可激活成纤维细胞中的TCF-荧光素酶报告基因，提示MAP3K1可诱导上皮细胞分泌激活因子，进而激活成纤维细胞内的WNT信号。相应地，Wnt7b的表达水平在野生型样本中较高，而在Map3k1敲除的尾段米勒管上皮细胞及MAP3K1缺陷角质形成细胞中较低。本研究揭示了时空特异性的旁分泌MAP3K1-WNT信号串扰在调控尾段米勒管延伸与雌性生殖道发育中的作用。整体实验设计：将3株经基因工程改造以升高MAP3K1表达（SAM）的人上皮HaCaT细胞独立样本，与3株经基因工程改造以降低MAP3K1表达（shRNA）的人上皮HaCaT细胞独立样本进行对照分析。