tailieunhanh - Báo cáo khoa học: Pathways involved in testicular germ cell apoptosis induced by H2O2 in vitro

The chitosanase fromStreptomycessp. N174 (CsnN174) is an inverting glycoside hydrolase belonging to family 46. Previous studies identified Asp40 as the general base residue. Mutation of Asp40 into glycine revealed an unexpectedly high residual activity. D40G mutation did not affect the stereochemical mechanism of catalysis or the mode of interaction with sub-strate. | ễFEBS Journal Pathways involved in testicular germ cell apoptosis induced by H2O2 in vitro Ankur Maheshwari1 Man M. Misro1 Archana Aggarwal1 Rajnesh K. Sharma2 and Deoki Nandan1 1 Department of Reproductive Biomedicine National institute of Health and Family Welfare New Delhi India 2 Department of Zoology Kurukshetra University India Keywords apoptosis germ cell H2O2 pathways testis Correspondence M. M. Misro Department of Reproductive Biomedicine National institute of Health and Family Welfare Baba Gang Nath Marg New Delhi 110067 India Fax 91 11 2610 1623 Tel 91 11 2616 5959 E-mail mm_misro@ Received 17 October 2008 revised 28 November 2008 accepted 3 December 2008 doi H2O2 induces apoptosis in variety of cells however the sensitivities of testicular germ cells to H2O2 are not known. In the present study H2O2 at concentrations in the range 1-10 pM was found to induce apoptosis in testicular germ cells in vitro. Following 1 h of treatment with 10 pM H2O2 a 10-fold rise in the percentage of apoptotic cells was observed. Induction of germ cell apoptosis was directly associated with a significant P increase in lipid peroxidation and a concomitant decrease in superoxide dismutase and catalase activity. Examination of apoptotic signalling pathways revealed an increased expression of extrinsic Fas FasL and caspase-8 and intrinsic Bid Bak Bad Bax and caspase-9 markers as well as p53 along with a simultaneous decrease in the Bcl-2 protein at the highest concentration of H2O2 exposure. Both c-jun N-terminal kinase and p38 phosphorylated forms were found to be up-regulated. Interestingly up-regulation of the nuclear transcription factor kappa B was also observed. The respective transcripts for many of the above proteins followed an identical trend. Caspase-3 activity was also estimated to be 30-fold higher. Taken together the above data indicate that testicular germ cells are prone to apoptosis at very low concentrations of H2O2