(CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons)
Programmed cell death, otherwise known as apoptosis, is an important physiological process that allows the body to get rid of cells that are no longer needed or are damaged. These functions help foster normal growth and development as well as prevent cancer. Apoptosis is a highly regulated process that involves various caspase enzymes, with caspase-3 being among the “executioner” enzymes responsible for the final stages of apoptosis and ultimate cellular self-destruction. In other words, activation of caspase-3 is considered the point of no return. Failure of apoptosis to remove dysfunctional cells can result in cancer, various autoimmune diseases, as well as various neurodegenerative diseases (National Human Genome Research Institute).
Interestingly, hibernating animals routinely experience stressors known to trigger apoptosis in non-hibernators such as anorexia, hypothermia, acidosis, and ischemia/reperfusion. During the winter when environmental conditions are harsh and food resources low, ground squirrels undergo cycles of arousal and torpor during which time their metabolism and body temperature drop. Although well-adapted for hibernation, up to 40% of adult ground squirrels do not survive the winter. Researchers at the University of Las Vegas – Nevada were therefore curious whether torpor and arousals affect apoptotic pathways in these animals as resilience to apoptosis would be necessary to survive hibernation. Their results were published in Physiological and Biochemical Zoology.
Studying golden-mantled ground squirrels (Spermphilus [Callospermophilus] lateralis, the researchers discovered that, although caspase-3 enzyme activity nearly doubled during torpor and arousals, it did not trigger cell death in these animals. In fact, very few (0.001-0.009%) of their cells showed signs of apoptosis during hibernation. Just how these animals are able to block the effects of caspase-3 are not known. Understanding the molecular switches that regulate apoptosis would help inform the development of therapies for cancer as well as other diseases associated with dysregulated apoptosis.
Sources:
National Human Genome Research Institute
MD Treat, AJ Marlon, F van Breukelen. Incomplete caspase 3 activation and mitigation of apoptosis in hibernating ground squirrels, Spermophilus lateralis. Physiological and Biochemical Zoology. 96(2): 128-137, 2023.
Categories: Environment, Extreme Animals, Hibernation and Hypoxia, Illnesses and Injuries, Nature's Solutions
Tags: apoptosis, biology, cancer, development, health, nutrition, squirrel, torpor, wellness
Life Lines by Dr. Dolittle 