Alternative splicing of the telomerase catalytic subunit in human oocytes and embryos
Alternative splicing of the telomerase catalytic subunit in human oocytes and embryos
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DOI：
10.1093/molehr/5.9.845
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发表时间：
1999-09-01
影响因子：
4
通讯作者：
Cohen, J
中科院分区：
文献类型：
--
作者：
Brenner, CA;Wolny, YM;Cohen, J
人类端粒酶催化亚单位(HTCS)是一种核糖核蛋白，可合成染色体末端的端粒重复序列。端粒酶活性被认为是在永生(癌症)和生殖细胞中维持正常端粒长度所必需的。本研究的目的是检测端粒酶基因在人卵母细胞不同减数分裂阶段和胚胎中的表达。分析了正常和异常的人卵母细胞、植入前胚胎和囊胚中hTcS转录的存在和表达。逆转录聚合酶链式反应(RT-PCR)检测多种端粒酶基因产物。对这些扩增片段的DNA测序表明，存在与其他端粒酶逆转录酶(RT)共识结构域对齐的选择性剪接变体。令人惊讶的是，在未受精和未成熟的配子以及植入前的胚胎中，HTCS的表达显示了三种不同的PCR产物大小，457、421和275bp。在卵母细胞中，275bpDNA产物的频率为6.6%(2/30)，而在发育不良的人类植入前胚胎中，这一比例为56.6%(17/30)(P<；0.005)。在人类植入前胚胎中出现交替剪接的mRNA变体可能意味着端粒酶活性的缺乏，从而表明染色体与端粒缩短有关。
The human telomerase catalytic subunit (hTCS) is a ribonucleoprotein which synthesizes telomere repeats on the ends of chromosomes. Telomerase activity is thought to be essential in maintaining normal telomere length in immortal (cancer) and germ cells. The objective of this study was to determine the gene expression of telomerase mRNA in human oocytes at different meiotic stages and in embryos. Normal and abnormal human oocytes, preimplantation embryos, and blastocysts were analysed for the presence and expression of the hTCS transcripts. Multiple telomerase mRNA products were identified by reverse transcription-polymerase chain reaction (RT-PCR) using primers within the reverse transcriptase domain. DNA sequencing of these amplicons suggest that there are alternative splicing variants which align to other telomerase reverse transcriptase (RT) consensus domains. Surprisingly, in unfertilized and immature gametes, as well as preimplantation embryos, hTCS expression revealed three different PCR product sizes, 457, 421 and 275 bp. The frequency of the 275 bp DNA product was 6.6% in oocytes (two out of 30) compared with 56.6% (17 out of 30) in poorly developing human preimplantation embryos (P < 0.005). The presence of alternately spliced mRNA variants in human preimplantation embryos may suggest a lack of telomerase activity and thus chromosomes associated with shortened telomeres.