The investigation of effect of the klotho protein on the expression of NHEJ repair pathway genes Ku70, Ku80 and DNA-PK and on the working of their proteins.

Aging is a process in which the balance of the organism's relations with the environment over time results in favor of the environment. The rate of progress of this process depends on the interaction of the organism with the environment and its inherited characteristics. In this study the Klotho (Kl) gene, which is one of the genetic factors associated with aging was discussed. The Klotho gene, which first described in the mice located in the q-arm of chromosome 13 in the human, and encodes the type 1 single-pass transmembrane glycoprotein located in the Golgi apparatus. Athough there are some studies suggesting how Klotho affects intracellular molecular mechanisms, the role of this protein on the DNA double strand brekage (DSB) repair mechanisms, which are also known to have an effect on the aging process, cannot be elucidate yet. In this study, we aimed to investigate how Klotho affects the expression of some genes, especially known to work in the non-homologous end joint (NHEJ) repair, one of the repair mechanisms in the DNA DSB repair. In the study, the mouse hippocampal cell lines HT22 cells were used. First, the IC50 dose of Endosulfan, which is known to produce double-chain fracture in DNA, was determined. Then, using this dose the HT22 cells were treated in different experimental protocols, and finally RNA and protein isolation was performed in those cells. From obtained total RNAs the cDNAs were generated, and then changes in the expressions of the Ku70, Ku80 and DNA-PK genes were determined by RT-PCR. Changes in protein level were determined by Western Blotting methods. The results showed that the expression levels of studied genes increased significantly only in endosulfan-treated cells, but was not increased in the cells which also treated with Klotho protein. These results suggest that Klotho minimizes the harmful effect of Endosulfan and suppresses the NHEJ pathway. Thus, for the first time in the literature, the role of Klotho protein in the NHEJ repair pathway was investigated.