51. Antiapoptotic signaling as a cytoprotection mechanism during Mammalian hibernation

Apoptosis (programmed cell death) is an essential natural biological process. A synergy between proapoptotic and antiapoptotic proteins, interacting at several signalling crossroads determines a cell’s commitment to mitochondria-activated apoptosis. We proposed that changes in expression of antiapoptotic proteins may aid cytoprotection during hibernation of thirteen-lined ground squirrels ( Spermophilus tridecemlineatus ) to cope with events including low body temperatures, changes in metabolic requirements, ischemia–reperfusion, muscle disuse, etc. Immunoblotting was used to analyse expression of proteins associated with apoptosis in three tissues. In brown adipose Bcl-2, cIAP and xIAP decreased significantly during torpor (compared with euthermia) whereas p-Bcl-2 (Thr 56), p-Bcl-2 (Ser 70), Bcl-X L , Bcl-3, Mcl-1, and BI-1 were unaltered. In skeletal muscle only xIAP levels were altered during hibernation. In heart, most proteins increased significantly, except for Bcl-X L (significant decrease) and xIAP/BI-1 (unchanged). The data show that antiapoptotic pathways have organ-specific responses in hibernators with a prominent potential role in heart. Funded by NSERC Canada. For more information go to: www.carleton.ca/∼kbstorey .