Investigation of the effects of klotho protein on P38 MAPK expression in hippocampal HT22 cell series

Klotho protein is a highly conserved protein encoded by the Klotho gene localized in chromosome 5 (5; 5 G3), 12 (12p12) and 13 (13q13.1), respectively, in mouse, rat and human. The Klotho gene is alternatively transcribed into at least two mRNAs, one encoding the large transmembrane (1012 and 1014 aa, -130 kDa, respectively in human and mouse), and the other in short soluble form (550 aa, ∼70 kDa). A defect in Klotho gene expression in the mouse were caused the short life and the many diseases in mutant mice, as similar to human aging. Mitogen-activated protein kinases (MAPKs) are serine-threonine protein kinases, which are activated by growth factors and other signaling molecules and are translocated into the nucleus, mediating intracellular signal transduction of various cellular activities. The mammalian MAPK family includes extracellular signal regulatory kinases (ERK), c-Jun NH2-terminal kinases (JNK; also known as stress-activated protein kinase or SAPK) and the p38 family. The p38 gene is located on the p arm of chromosome 6 in humans (6p21.31) and consists of 22 exons. In humans and mice, the p38 protein consists of 360 amino acids and has a molecular weight of 38 kDA. P38 MAPKs were initially identified as activated proteins in response to cellular stresses such as hyperosmolarity and pro-inflammatory cytokines. P38 MAP kinases are activated primarily by phosphorylation by MAPKK isoforms, MKK3 and MKK6. Studies have shown that p38MAPK also has role in to responding to DNA damage and redox imbalance, which plays an important role in cellular aging. In this study, the effect of Klotho protein on p38 MAPK expression in HT22 hippocampal cell line where DNA double chain fracture was produced by endusulfan, was investigated. When the Real Time PCR and Western Blot results were examined, it was observed that p38MAPK expression, which increased approximately 100 times only in Endosulfan treated cells, was limited in cells using Klotho protein. This is probably due to the suppression of the negative effects of Endosulfan by the Klotho protein. However, in order to be able to say this clearly, it is necessary to determine the level of double chain breakage in DNA and also to study the phospho-p38 protein amount of p38 which is activated by phosphorylation. Key worlds: Aging, Klotho, p38 MAPK, Cell culture