Antiapoptotic Members Inhibit Cold-induced Apoptosis And Its Modulation Mechanism In Saccharomyces Cerevisiae

Cold and apoptosis are tightly correlated and the research on cold-induced apoptosis has become one of the most important fields in the transplantation medicine area. The signal transduction involved in the cold-induced apoptosis is anfractuous, either mediated or modulated by reactive oxygen species (ROS), Ca²⁺, Fe²⁺ and cold-relevant genes in vivo. However little is known about the situation in the yeast. As yeast has been extensively characterized both biochemically and genetically with its genetic tractability, it has been used extensively as models for genetic analysis of various complex pathways and processes, including cell division, transcription and receptor-mediated signal transduction. We transformed antiapoptotic genes Bcl-2, CED-9 and PpBI-1 into the yeast to evaluate their function of resistance to cold stress. The results are as follows:(1) Cold induced apoptosis in yeast cells, moreover, yeast cells display representive features such as chromatin condensation, DNA fragmentation and chromatin margination.(2) The expression of Bcl-2, CED-9 and PpBI-1 significantly inhibits cold-induced apoptosis in the yeast.(3) ROS and Ca²⁺ act as intracellular second messager to induce cell apoptosis. The potential molecular mechanism of cold induced cell apoptosis and how Bcl-2, CED-9 and PpBI-1 fights against cold stess in the yeast is associated with the increase in intracellular ROS and Ca²⁺ induced by cold. The expression of PpBI-1 inhibits the increase in intracellular Ca²⁺, thus alleviates cell injuries induced by Ca²⁺. (4) Cold induced an increase in intracellular ROS, however it can not be inhibited directly by the expression of PpBI-1. In order to further investigate the role of ROS in the process of cold-induced apoptosis and the mechanism of antiapoptotic members mediating ROS, we used wild strain CY4 and gsh1 mutant strain CY8 to investigate the role of PpBI-1 mediating ROS. Results showed that expression of PpBI-1 could restore the growth of CY8 and significantly inhibit cold-induced cell apoptosis when adding exogenous GSH, however expression of PpBI-1 could not restore the growth of CY8 and inhibit cold-induced cell apoptosis without exogenous GSH. These data suggest the pathway of PpBI-1 against ROS stress is associated with GSH directly or indirectly.