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. 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，具备多种细胞类型特异性功能，相关机制迄今尚未完全阐明。本研究阐明了MAP3K1在雌性生殖道（female reproductive tract，FRT）发育中的功能。MAP3K1激酶结构域缺陷型雌性小鼠（Map3k1ΔKD）可表现出阴道闭锁、分娩失败与不育表型。该缺陷对应胚胎时期作为雌性生殖道前体的米勒管（Müllerian duct，MD）发育异常，以及新生小鼠尾段阴道扭曲、阴道-尿生殖窦融合完全受阻。尽管MAP3K1可通过c-Jun氨基末端激酶（c-Jun N-terminal kinase，JNK）与细胞外调节蛋白激酶（Extracellular Signal-Regulated Kinase，ERK）激活上皮细胞内的WNT信号，但在体内胚胎尾段米勒管中，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MAP3K1功能完整而非缺陷型上皮细胞的条件培养基，可激活成纤维细胞内的TCF荧光素酶报告基因，这表明MAP3K1可诱导上皮细胞分泌激活因子，进而激活成纤维细胞中的WNT信号。相应地，Wnt7b在野生型个体中呈高表达，而在Map3k1敲除的尾段米勒管上皮细胞及MAP3K1缺陷型角质形成细胞中表达量显著降低。本研究数据揭示了在尾段米勒管延伸与雌性生殖道发育的调控过程中，存在时空依赖性的MAP3K1-WNT旁分泌串扰机制。本研究对3批独立的经基因修饰后MAP3K1表达上调（SAM）的人上皮HaCaT细胞，与3批独立的经基因修饰后MAP3K1表达下调（shRNA）的人上皮HaCaT细胞进行了对比分析。