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Modulation of stress proteins and apoptotic regulators in the anoxia tolerant turtle brain
Author(s) -
Kesaraju Shailaja,
SchmidtKastner Rainald,
Prentice Howard M.,
Milton Sarah L.
Publication year - 2009
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2009.06068.x
Subject(s) - hsp60 , apoptosis , biology , hsp27 , heat shock protein , microbiology and biotechnology , western blot , cytosol , mitochondrion , oxidative stress , hsp70 , programmed cell death , biochemistry , gene , enzyme
Freshwater turtles survive prolonged anoxia and reoxygenation without overt brain damage by well‐described physiological processes, but little work has been done to investigate the molecular changes associated with anoxic survival. We examined stress proteins and apoptotic regulators in the turtle during early (1 h) and long‐term anoxia (4, 24 h) and reoxygenation. Western blot analyses showed changes within the first hour of anoxia; multiple stress proteins (Hsp72, Grp94, Hsp60, Hsp27, and HO‐1) increased while apoptotic regulators (Bcl‐2 and Bax) decreased. Levels of the ER stress protein Grp78 were unchanged. Stress proteins remained elevated in long‐term anoxia while the Bcl‐2/Bax ratio was unaltered. No changes in cleaved caspase 3 levels were observed during anoxia while apoptosis inducing factor increased significantly. Furthermore, we found no evidence for the anoxic translocation of Bax from the cytosol to mitochondria, nor movement of apoptosis inducing factor between the mitochondria and nucleus. Reoxygenation did not lead to further increases in stress proteins or apoptotic regulators except for HO‐1. The apparent protection against cell damage was corroborated with immunohistochemistry, which indicated no overt damage in the turtle brain subjected to anoxia and reoxygenation. The results suggest that molecular adaptations enhance pro‐survival mechanisms and suppress apoptotic pathways to confer anoxia tolerance in freshwater turtles.