Mixed spermatogenic germ cell nuclear extracts exhibit high base excision repair activity
Mixed spermatogenic germ cell nuclear extracts exhibit high base excision repair activity
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DOI：
10.1093/nar/29.6.1366
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发表时间：
2001-03-15
影响因子：
14.9
通讯作者：
Walter, CA
中科院分区：
文献类型：
--
作者：
Intano, GW;McMahan, CA;Walter, CA
在lad转基因中，生精细胞表现出比体细胞更低的自发突变频率，并且许多碱基切除修复（BER）基因在睾丸中表现出最高的表达水平。在这项研究中，尿嘧啶-DNA糖基化酶启动的BER活性在从三种小鼠品系中的每一种获得的组织制备的核提取物中测量。对于所有三种品系，来自混合生精生殖细胞的提取物显示出最大的活性，其次是肝脏，然后是脑，并且对于给定组织的活性在三种品系中是一致的，通过蛋白质印迹分析检查各种BER蛋白质的水平，发现其与活性水平一致。从纯化的支持细胞（生精上皮的体细胞组分）制备的核提取物显示出比混合的生精细胞型核提取物显著更低的活性，从而表明在混合的生殖细胞核提取物中观察到的高BER活性不是所有睾丸细胞类型的特征。测定来自胸腺细胞和小肠的核提取物以评估有丝分裂活性细胞类型中的活性：和组织。总体而言，表现出最大至最低活性的组织/细胞的顺序为混合生殖细胞>支持细胞>胸腺细胞>小肠>肝脏>脑。
Spermatogenic cells exhibit a lower spontaneous mutation frequency than somatic tissues in a lad transgene and many base excision repair (BER) genes display the highest observed level of expression-in the:testis. In this study, uracil-DNA glycosylase-initiated BER activity was measured in nuclear extracts prepared from tissues obtained from each of three mouse strains, Extracts from mixed spermatogenic germ cells displayed the greatest activity followed by liver then brain for all three strains, and the activity for a given tissue was consistent among the three strains, Levels of various BER proteins were examined by western blot analyses and-found to be consistent with activity levels. Nuclear extracts prepared from purified Sertoli cells, a somatic component of the seminiferous epithelium, exhibited significantly lower activity than mixed spermatogenic cell-type nuclear extracts, thereby suggesting that the high BER activity observed in mixed germ cell nuclear extracts was not a characteristic of all testicular cell types, Nuclear extracts from: thymocytes and small intestines were assayed to assess activity in a mitotically active cell type: and tissue. Overall, the order of tissues/cells exhibiting the greatest to lowest activity was mixed germ cells > Sertoli cells > thymocytes > small intestine > liver > brain.