Post-translational modifications of mitochondrial proteins in hibernating thirteen-lined ground squirrels, Ictidomys tridecemlineatus
Abstract
Some species of hibernating endotherms suppress whole body metabolism by approximately 95%. I hypothesized that post-translational modifications (PTMs) of mitochondrial proteins regulate the reversible suppression of mitochondrial metabolism during hibernation. I predicted that abundance of PTMs between torpor and euthermic states of hibernation would differ based on the regulatory action of the modification. I compared abundance of acetylation, hydroxylation, phosphorylation, succinylation, sulfhydration, SUMOylation, and S-nitrosylation in torpid, interbout euthermic, and summer euthermic thirteen-lined ground squirrels (TLGS) using one-dimensional immunoblotting. I then used two-dimensional immunoblotting for PTMs displaying many significant differences among groups to further characterize differentially modified proteins. I observed differential modifications in proteins of various molecular masses among experimental groups in all one and two-dimensional immunoblots. My findings demonstrate that PTMs of mitochondrial proteins differ among physiological states, correlating with changes in liver mitochondrial respiration, supporting that reversible suppression of mitochondrial respiration during hibernation may be regulated by PTMs.