Loss of telomerase activity during male germ cell differentiation.
Loss of telomerase activity during male germ cell differentiation.
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DOI：
10.1210/endo.138.9.5488
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发表时间：
1997-09
期刊：
影响因子：
4.8
通讯作者：
N. Ravindranath;Rakhi Dalal;Bogdan Solomon;D. Djakiew;M. Dym
中科院分区：
文献类型：
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作者：
N. Ravindranath;Rakhi Dalal;Bogdan Solomon;D. Djakiew;M. Dym
端粒酶是一种合成端粒并稳定端粒长度的酶，虽然已在睾丸中得到证实，但不同类型生殖细胞中端粒酶活性的确切表达尚不清楚。我们使用基于聚合酶链式反应的端粒重复扩增方法检测了大鼠从出生到成年的睾丸发育过程中的端粒酶活性。从出生到4周龄端粒酶活性相对较高，5~10周龄端粒酶活性较低，提示A型精原干细胞可能是表达端粒酶活性最高的群体。为了确定哪些生殖细胞表达端粒酶活性，分离了9日龄大鼠的A型精原细胞和成年大鼠的粗线期精母细胞、圆形精子细胞和附睾精子。A型精原细胞表达很强的端粒酶活性，含有粗线期精母细胞和圆形精细胞的部分也表达端粒酶活性，但水平相对较低。附睾精子端粒酶活性完全缺失。因此，端粒酶活性在A型精原干细胞中高水平表达，在精子发生过程中表达下调，在分化后的精子中缺失。
Although the activity of telomerase, an enzyme which synthesizes telomeres de novo and stabilizes telomere length has been demonstrated in the testis, the precise expression of activity in different germ cell types is not known. We examined telomerase activity using a PCR-based telomeric repeat amplification protocol during development of the rat testis from birth to adulthood. Telomerase activity was relatively high from birth to the 4th week of age, and then low between the 5th to 10th week, suggesting that the type A spermatogonial stem cells may be the population which is expressing the highest levels of telomerase activity. To ascertain which germ cells expresses the telomerase activity, purified populations of type A spermatogonia from 9-day old rats, and pachytene spermatocytes, round spermatids and epididymal spermatozoa from adult rats were isolated. While type A spermatogonia expressed very strong telomerase activity, the fractions containing pachytene spermatocytes and round spermatids also expressed telomerase activity, but at comparatively lower levels. Telomerase activity was totally absent in epididymal spermatozoa. Thus, it appears that the telomerase activity is expressed at high levels in the type A spermatogonial stem cells, is down-regulated during spermatogenesis, and is absent in the differentiated spermatozoa.