Investigation of expression patterns of High temperature requirement A2 (HtrA2) in some tissues and cell lines and its production in prokaryotic host

HtrA2 is the mitochondrial serine protease, expressed in almost all tissues. At stressful conditions, this protease is converted into a pro-apoptic factor and induces apoptosis. It has been showed that beside protease function, HtrA2 acts as a chaperone and is involved in the proper protein folding. Considering the importance of the HtrA2 enzyme in inducing apoptosis and its association with some diseases, the expression pattern of HtrA2 protein was evaluated in natural cell lines and some disease categories. PCR results obtained in the present study showed that the normal human gastric tissue express HtrA2 gene, but the HtrA2 gene was not expressed in gastric cancer form. Also, HtrA2 gene was expressed in human lung cancer tissue, SW480 cell lines and MS cell lines. According to different expression of HtrA2 gene in natural and diseases tissues and cell lines, there was no specific pattern indicating the association of expression of this protease with a disease. In the next step, due to the importance of HtrA2, the coloning of HtrA2 gene in pET21a (+) (expression vector) has been done and the recombinant vector was transformed to the E. coli TOP10 strain cells. Finally, protein expression was analyzed with SDS-PAGE electrophoresis. Then, the produced protein was purified with Ni-NTA Agarose and protease activity of HtrA2 was assayed by casein substarte with spectrophotometer. The results showed the produced protein is active, so the produced HtrA2 has natural structure and can be used for further research.