Department of Chemistry and Biochemistry, University of Colorado BioFrontiers Institute, Boulder, CO 80309-0596, USA, Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309-0596, USA and Department of Chemistry and Biochemistry, DePauw University, Greencastle, IN 46135, USA.
Nucleic Acids Res. 2013 Oct;41(19):8969-78. doi: 10.1093/nar/gkt653. Epub 2013 Jul 30.
Mutations in the gene for telomerase reverse transcriptase (hTERT) are associated with diseases including dyskeratosis congenita, aplastic anemia, pulmonary fibrosis and cancer. Understanding the molecular basis of these telomerase-associated diseases requires dependable quantitative measurements of telomerase enzyme activity. Furthermore, recent findings that the human POT1-TPP1 chromosome end-binding protein complex stimulates telomerase activity and processivity provide incentive for testing variant telomerases in the presence of these factors. In the present work, we compare multiple disease-associated hTERT variants reconstituted with the RNA subunit hTR in two systems (rabbit reticulocyte lysates and human cell lines) with respect to telomerase enzymatic activity, processivity and activation by telomere proteins. Surprisingly, many of the previously reported disease-associated hTERT alleles give near-normal telomerase enzyme activity. It is possible that a small deficit in telomerase activity is sufficient to cause telomere shortening over many years. Alternatively, mutations may perturb functions such as the recruitment of telomerase to telomeres, which are essential in vivo but not revealed by simple enzyme assays.
端粒酶逆转录酶（hTERT）基因的突变与包括先天性角化不良、再生障碍性贫血、肺纤维化和癌症在内的多种疾病有关。了解这些与端粒酶相关疾病的分子基础需要可靠的端粒酶酶活性定量测量。此外，最近的发现表明，人类 POT1-TPP1 染色体末端结合蛋白复合物刺激端粒酶活性和进程性，为在这些因素存在的情况下测试变体端粒酶提供了动力。在本工作中，我们比较了在两种系统（兔网织红细胞裂解物和人细胞系）中用 hTR RNA 亚基重建的多个与疾病相关的 hTERT 变体，涉及端粒酶酶活性、进程性以及端粒蛋白的激活。令人惊讶的是，许多先前报道的与疾病相关的 hTERT 等位基因具有近乎正常的端粒酶酶活性。可能是端粒酶活性的微小缺陷足以导致在多年时间内端粒缩短。或者，突变可能会破坏端粒酶与端粒的招募等功能，这些功能在体内是必不可少的，但在简单的酶测定中并没有被揭示。
