UAA Biological Sciences Weekly Seminar: Frank van Breukelen, Ph.D., April 25

Friday, April 25, 12-1 p.m. ConocoPhillips Integrated Science Building, Room 120

Frank van Breukelen, Ph.D., faculty at University of Nevada - Las Vegas, will present his research in a talk titled, "Hibernation: Homeostasis on Hold."

Abstract: During mammalian hibernation, metabolic rates may be as low as 1/100th of active rates. Although considered a critical component of homeostasis, protein metabolism represents an energetic cost that is incompatible with the severe metabolic depression of torpor. Concordant with energetic constraints, passive depression and active suppression both contribute to depression of transcription, translation and protein degradation. Passive depression of transcriptional elongation essentially ceases transcription during torpor. Nevertheless, the transcription factor, p53, moves into the nucleus during torpor, binds DNA and recruits RNA polymerase II. Van Breukelen's research shows there is no associated change in p53 target [mRNAs] consistent with the marked depression of transcription. While the bulk of translation is depressed during torpor through passive mechanisms, there is an accumulation of internal ribosome entry site-bearing messages on ribosomes. This accumulation may allow for preferential translation of stress proteins when animals arouse from torpor. Ubiquitylation, or the tagging of proteins for degradation, is less temperature sensitive than proteolysis per se. The result is an accumulation of polyubiquitylated proteins that must be reconciled during the interbout arousal. The imprecise coordination of these anabolic and catabolic pathways leads to physiological mismatches that van Breukelen suggests may lead to significant mortality during hibernation.

April Archive