Mizrak S C, Bogerd J, Lopez-Casas P P, Párraga M, Del Mazo J, de Rooij D G
Department of Endocrinology, Faculty of Biology, Utrecht University, Utrecht, The Netherlands.
Mol Reprod Dev. 2006 Nov;73(11):1361-6. doi: 10.1002/mrd.20548.
Phthalate esters are considered endocrine disruptors that interfere with the endocrine balance and development of the mammalian testis. Mono-2-ethylhexyl phthalate (MEHP), the active metabolite of the ubiquitously used plasticizer di-2-ethylhexyl phthalate (DEHP), acts upon Sertoli cells as initial target. By subtractive cDNA libraries we identified genes deregulated as response to MEHP in primary cultures of mouse Sertoli cells. The expression of mouse stress inducible protein 1 (Stip1) was detected as upregulated as a result of MEHP exposure. Stip1 is a cochaperone protein that is homologous to the human heat shock cognate protein 70 (hsc70)/heat shock protein 90 (hsp90)-organizing protein (Hop). To assess the presence and localization of Stip1 in mouse testis and its potential role in stress defense, we studied the expression pattern of the Stip1 protein by immunohistochemistry and of the mRNA by in situ hybridization. Both the protein and the mRNA of Stip1 were mainly found in the cytoplasm of all types of spermatogonia and spermatocytes up till zygotene, the expression decreased during late pachytene and was very weak in diplotene spermatocytes and round spermatids. Interestingly, this expression pattern resembled the pattern of stress sensitivity of spermatogenic cells in that the most sensitive cell types show the weakest expression of Stip1. This suggests an important role for Stip1 in the ability of germ cells to survive in stress conditions including high temperatures.
邻苯二甲酸酯被认为是内分泌干扰物，会干扰哺乳动物睾丸的内分泌平衡和发育。单-2-乙基己基邻苯二甲酸酯（MEHP）是广泛使用的增塑剂二-2-乙基己基邻苯二甲酸酯（DEHP）的活性代谢产物，其最初作用靶点是支持细胞。通过消减cDNA文库，我们在小鼠支持细胞原代培养物中鉴定出了因MEHP作用而失调的基因。结果发现，MEHP暴露导致小鼠应激诱导蛋白1（Stip1）的表达上调。Stip1是一种辅助伴侣蛋白，与人热休克同源蛋白70（hsc70）/热休克蛋白90（hsp90）组织蛋白（Hop）同源。为了评估Stip1在小鼠睾丸中的存在和定位及其在应激防御中的潜在作用，我们通过免疫组织化学研究了Stip1蛋白的表达模式，并通过原位杂交研究了mRNA的表达模式。Stip1的蛋白和mRNA主要存在于所有类型的精原细胞和直到偶线期的精母细胞的细胞质中，在粗线期后期表达下降，在双线期精母细胞和圆形精子细胞中非常弱。有趣的是，这种表达模式类似于生精细胞的应激敏感性模式，即最敏感的细胞类型Stip1表达最弱。这表明Stip1在生殖细胞在包括高温在内的应激条件下存活的能力中起重要作用。
