外源性ATM基因对辐射诱导AT细胞端粒酶逆转录酶mRNA表达的影响

Effects of exogenous ATM gene on mRNA expression of human telomerase reverse transcriptase in AT cells induced by irradiation

通过观察外源性毛细血管扩张性共济失调症突变基因(Ataxia-telangiectasiamutation,ATM)对毛细血管扩张性共济失调症(Ataxia-telangiectasia,AT)患者皮肤的成纤维细胞系AT5BIVA(AT细胞)端粒酶逆转录酶(humantelomerasereversetranscriptase,hTERT)mRNA表达的影响,探讨ATM对hTERT的调控作用。采用RT-PCR法,对比ATM基因转染前、后AT细胞hTERTmRNA表达的变化及与源自正常人皮肤的成纤维细胞系GM0639(GM细胞)相比的差异;以及细胞经3Gy60Coγ射线照射后其hTERTmRNA表达的变化。结果显示,未照射时,GM细胞hTERTmRNA表达呈阴性,AT细胞hTERTmRNA表达呈阳性,转染ATM基因后的ATM+-AT细胞其hTERTmRNA的表达明显下降(p<0.05);60Coγ射线照射后,GM细胞hTERTmRNA表达呈阳性,AT细胞、空载体AT细胞(PEBS7-AT细胞)和ATM+-AT细胞hTERTmRNA的表达量比未照射时明显增加(p<0.05),ATM+-AT细胞hTERTmRNA相对表达量的增加低于AT细胞和空载体AT细胞(p<0.05)。提示ATM可下调hTERTmRNA的表达;电离辐射可诱导细胞hTERTmRNA表达;端粒酶参与DNA损伤修复。

The study is to observe effects of exogenous ATM gene on mRNA expression of hTERT （human telomerase reverse transcriptase） in fibroblast cells （AT5BIVA cells） from skin of Ataxia-telangiectasia （AT） patients and to study the regulation of ATM to hTERT. Using reverse transcription polymerase chain reaction （RT-PCR）, mRNA expression of hTERT in AT. PEBS7-AT, ATM^＋-AT and GM cells irradiated with 0 and 3Gy of ^60Coγ-rays were examined respectively. The difference of the mRNA expression of hTERT among AT. PEBS7-AT, ATM^＋-AT and GM cells were analyzed. Difference of the mRNA expression of hTERT between 0Gy and 3Gy groups was analyzed, too. The results showed that the mRNA expression of hTERT in GM cells was negative, but positive mRNA expression of hTERT in AT cells. The mRNA expression of hTERT in ATM^＋-AT cells decreased significantly （p〈0.05）. After exposure to ^60Coγ-rays, the mRNA expression of hTERT in GM cells was positive, and that in AT, PEBS7-AT, ATM^＋-AT cells was increased （p〈0.05）. The increase of relative expression of hTERT mRNA in ATM^＋-AT cells was lower than that in AT and PEBS7-AT cells respectively （p〈0.05）. It is postulated that exogenous ATM is able to downregulate the mRNA expression of hTERT in AT cells, ionizing radiation can induce the mRNA expression of hTERT in cells and telomerase anticipates the repair of damaged DNA.