PDF(Pubmed)
Abstract：
Telomeres are nucleoprotein structures at the end of chromosomes that maintain their integrity. Mutations in genes coding for proteins involved in telomere protection and elongation produce diseases such as dyskeratosis congenita or idiopathic pulmonary fibrosis known as telomeropathies. These diseases are characterized by premature telomere shortening, increased DNA damage and oxidative stress. Genetic diagnosis of telomeropathy patients has identified mutations in the genes TERT and TERC coding for telomerase components but the functional consequences of many of these mutations still have to be experimentally demonstrated. The activity of twelve TERT and five TERC mutants, five of them identified in Spanish patients, has been analyzed. TERT and TERC mutants were expressed in VA-13 human cells that express low telomerase levels and the activity induced was analyzed. The production of reactive oxygen species, DNA oxidation and TRF2 association at telomeres, DNA damage response and cell apoptosis were determined. Most mutations presented decreased telomerase activity, as compared to wild-type TERT and TERC. In addition, the expression of several TERT and TERC mutants induced oxidative stress, DNA oxidation, DNA damage, decreased recruitment of the shelterin component TRF2 to telomeres and increased apoptosis. These observations might indicate that the increase in DNA damage and oxidative stress observed in cells from telomeropathy patients is dependent on their TERT or TERC mutations. Therefore, analysis of the effect of TERT and TERC mutations of unknown function on DNA damage and oxidative stress could be of great utility to determine the possible pathogenicity of these variants.
摘要：
端粒是染色体末端的核蛋白结构，保持其完整性。编码与端粒保护和延伸有关的蛋白质的基因中的突变会产生疾病，例如先天性角化不良或称为端粒病的特发性肺纤维化。这些疾病的特征是端粒过早缩短，增加DNA损伤和氧化应激。端粒病患者的遗传诊断已经鉴定了编码端粒酶组分的基因TERT和TERC中的突变,但是这些突变中的许多的功能后果仍然需要实验证明。十二个TERT和五个TERC突变体的活性，其中5人在西班牙患者中被确认，已被分析。TERT和TERC突变体在表达低端粒酶水平的VA-13人细胞中表达,并分析诱导的活性。活性氧的产生，端粒的DNA氧化和TRF2缔合，测定DNA损伤反应和细胞凋亡。大多数突变呈现端粒酶活性降低，与野生型TERT和TERC相比。此外,几种TERT和TERC突变体的表达诱导了氧化应激，DNA氧化,DNA损伤,减少了shelterin成分TRF2向端粒的募集，并增加了细胞凋亡。这些观察结果可能表明，在端粒病患者的细胞中观察到的DNA损伤和氧化应激的增加取决于其TERT或TERC突变。因此,分析未知功能的TERT和TERC突变对DNA损伤和氧化应激的影响对于确定这些变体可能的致病性非常有用。
