Vyjayanti V N, Rao Kalluri Subba
ICMR Center for Research on Aging and Brain, CRAB, Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Andhra Pradesh 500046, India.
Neurosci Lett. 2006 Jan 23;393(1):18-22. doi: 10.1016/j.neulet.2005.09.053. Epub 2005 Oct 14.
Linearised pUC 19 DNA with cohesive, blunt and non-matching ends, generated by prior treatment with different restriction enzymes was presented as substrate to measure the NHEJ activity to repair DNA double strand breaks in extracts prepared from isolated neurons from neonatal, young adult and old rat cerebral cortex. Highest end joining activity was noticed with the substrates having cohesive 3' overhang (PstI) or 5' overhang (EcoRI) ends and this activity is significantly reduced with age. However, blunt and non-matching ends were very poorly repaired at all ages. Further, the end joining activity in neurons is not faithful and sequence changes occur during the repair process. Also, the end joining activity in old neuronal extracts, but not in young extracts, was found to decline very rapidly with time of cold storage. These findings, the first of their kind, thus demonstrate that neuronal cells have the capacity to repair DNA double strand breaks through error prone NHEJ mode and that the cohesive end joining activity decreases with age of the animal.
将经不同限制酶预先处理产生的具有粘性末端、平端和不匹配末端的线性化pUC 19 DNA作为底物，以测量从新生、年轻成年和老年大鼠大脑皮层分离的神经元提取物中修复DNA双链断裂的非同源末端连接（NHEJ）活性。对于具有3'突出端（PstI）或5'突出端（EcoRI）的粘性末端底物，观察到最高的末端连接活性，并且这种活性随年龄显著降低。然而，平端和不匹配末端在所有年龄段的修复效果都非常差。此外，神经元中的末端连接活性并不精确，在修复过程中会发生序列变化。而且，发现老年神经元提取物中的末端连接活性，但年轻提取物中没有，会随着冷藏时间迅速下降。这些同类研究中的首个发现表明，神经元细胞有能力通过易出错的NHEJ模式修复DNA双链断裂，并且粘性末端连接活性随动物年龄增长而降低。
