Telomere length in male germ cells is inversely correlated with telomerase activity
Telomere length in male germ cells is inversely correlated with telomerase activity
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DOI：
10.1095/biolreprod63.2.591
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发表时间：
2000-08-01
影响因子：
3.6
通讯作者：
Dym, M
中科院分区：
文献类型：
--
作者：
Achi, MV;Ravindranath, N;Dym, M
端粒，染色体末端的非编码序列，随着每次细胞分裂而逐渐缩短。精子有很长的端粒，但它们缺乏端粒从头合成和添加所必需的端粒酶活性。我们进行了端粒限制性片段分析，以比较未成熟大鼠睾丸（含A型精原细胞）和成年大鼠睾丸（含更多分化的生殖细胞）的端粒长度。未成熟睾丸的平均端粒长度明显短于成年睾丸，这表明A型精原细胞的端粒可能比更分化的生殖细胞短。在此基础上，分离出未成熟睾丸中的A型精原细胞和成年睾丸中的粗线期精母细胞和圆形精子细胞。粗线期精母细胞的端粒比A型精原细胞长。令人惊讶的是，虽然统计学上不显着，圆形精子细胞显示端粒长度减少。附睾精子端粒长度最长。与此形成鲜明对比的是，端粒酶活性，测量端粒重复序列扩增协议是非常高的A型精原细胞，减少粗线期精母细胞和圆形精子细胞，是完全不存在的附睾精子。总之，这些结果表明，在从精原细胞到精子的交配生殖细胞的发育过程中，端粒长度增加，并且与端粒酶活性的表达呈负相关。
Telomeres, the noncoding sequences at the ends of chromosomes, progressively shorten with each cellular division. Spermatozoa have very long telomeres but they lack telomerase enzymatic activity that is necessary for de novo synthesis and addition of telomeres. We performed a telomere restriction fragment analysis to compare the telomere lengths in immature rat testis (containing type A spermatogonia) with adult rat testis (containing more differentiated germ cells). Mean telomere length in the immature testis was significantly shorter in comparison to adult testis, suggesting that type A spermatogonia probably have shorter telomeres than more differentiated germ cells. Then, we isolated type A spermatogonia from immature testis, and pachytene spermatocytes and round spermatids from adult testis. Pachytene spermatocytes exhibited longer telomeres compared to type A spermatogonia. Surprisingly, although statistically not significant, round spermatids showed a decrease in telomere length. Epididymal spermatozoa exhibited the longest mean telomere length. In marked contrast, telomerase activity, measured by the telomeric repeat amplification protocol was very high in type A spermatogonia, decreased in pachytene spermatocytes and round spermatids, and was totally absent in epididymal spermatozoa. in summary, these results indicate that telomere length increases during the development of mate germ cells from spermatogonia to spermatozoa and is inversely correlated with the expression of telomerase activity.