The membrane skeletal complex, protein 4.1G-membrane palmitoylated protein 6 (MPP6), is localized in spermatogonia and early spermatocytes of mouse seminiferous tubules. In this study, we investigated the Lin7 family of scaffolding proteins, which interact with MPP6. By immunohistochemistry, Lin7a and Lin7c were localized in germ cells, and Lin7c had especially strong staining in spermatogonia and early spermatocytes, characterized by staging of seminiferous tubules. By immunoelectron microscopy, Lin7 localization appeared under cell membranes in germ cells. The Lin7 staining pattern in seminiferous tubules was partially similar to that of 4.1G, cell adhesion molecule 1 (CADM1), and melanoma cell adhesion molecule (MCAM). Lin7-positive cells included type A spermatogonia, as revealed by double staining for Lin28a. Lin7 staining became weaker in MPP6-deficient mice by immunohistochemistry and western blotting, indicating that MPP6 transports and maintains Lin7 in germ cells. The histology of seminiferous tubules was unchanged in MPP6-deficient mice compared to that of wild-type mice. In cultured spermatogonial stem cells maintained with glial cell line-derived neurotropic factor (GDNF), Lin7 was clearly expressed and immunolocalized along cell membranes, especially at cell-cell junctions. Thus, Lin7 protein is expressed in germ cells, and Lin7, particularly Lin7c, is a useful marker for early spermatogenesis.

中文翻译：

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小鼠曲细精管中膜骨架蛋白复合物中的支架蛋白Lin7家族。

膜骨架复合物蛋白4.1G-膜棕榈酰化蛋白6（MPP6）位于小鼠精管的精原细胞和早期精母细胞中。在这项研究中，我们研究了与MPP6相互作用的脚手架蛋白Lin7家族。通过免疫组织化学，Lin7a和Lin7c定位在生殖细胞中，并且Lin7c在精原细胞和早期精母细胞中的染色特别强，其特征是生精小管的分期。通过免疫电子显微镜，Lin7定位出现在生殖细胞的细胞膜下。曲细精管中的Lin7染色模式与4.1G，细胞粘附分子1（CADM1）和黑素瘤细胞粘附分子（MCAM）的部分相似。Lin7阳性细胞包括A型精原细胞，如Lin28a的两次染色所揭示。通过免疫组织化学和蛋白质印迹，在MPP6缺陷小鼠中，Lin7染色变弱，表明MPP6在生殖细胞中转运并维持Lin7。与野生型小鼠相比，MPP6缺陷小鼠的曲细精管的组织学没有变化。在神经胶质细胞源性神经营养因子（GDNF）维持的培养的精原干细胞中，Lin7清楚地表达并沿细胞膜免疫定位，特别是在细胞-细胞连接处。因此，Lin7蛋白在生殖细胞中表达，Lin7，尤其是Lin7c，是早期精子发生的有用标记。在神经胶质细胞源性神经营养因子（GDNF）维持的培养的精原干细胞中，Lin7清楚地表达并沿细胞膜免疫定位，尤其是在细胞-细胞连接处。因此，Lin7蛋白在生殖细胞中表达，Lin7，尤其是Lin7c，是早期精子发生的有用标记。在神经胶质细胞源性神经营养因子（GDNF）维持的培养的精原干细胞中，Lin7清楚地表达并沿细胞膜免疫定位，特别是在细胞-细胞连接处。因此，Lin7蛋白在生殖细胞中表达，Lin7，尤其是Lin7c，是早期精子发生的有用标记。