Abstract 11422: Coupling Factor 6 Accelerates Aging and Shortens Lifespan Through Reduced Autophagy by Proton-Mediated Histone Acetylation
Backgrounds: Proton regulates cellular functions by modulating the charge and structure of macromolecules, but its role in aging is unknown. We recently identified a circulating peptide coupling factor 6 (CF6) which binds to the molecular rotary motor at the plasma membrane, resulting in proton import. Autophagy mediates protective effects in organ damage, and its reduction is associated with accelerated aging. We investigated whether overexpression of CF6 contributes to reduced autophagy and accelerated aging by intracellular protons.
Methods and Results: We generated transgenic mouse overexpressing CF6 by two folds (TG). Intracellular pH measured by 31P-MRS was decreased by 0.1 to 0.15 unit in various organs of TG except for the adipose tissue, being consistent with distribution of the CF6 receptor. Despite no difference in blood pressures, lifespan was shortened in TG (n=20) manifesting early senescence-associated phenotype such as signs of hair graying and sparseness, and wrinkly skin compared with wild-type mice (WT, n=13) littermates (median values; 108±2 vs 131±11 months, p<0.05). Microarray for autophagy-related genes revealed that overexpression of CF6 decreased Atg7, a key effector for both Atg8- and Atg12-conjugation systems in the heart and kidney of TG. In western blot, histone-4 acetylation at lysine 5 (H4K5) was increased in the TG heart, kidney, and liver compared with those of WT, being accompanied by decreased histone deacetylase-1 and 3. Chip assay showed that interaction between H4K5 and the Atg7 promoter at -440 through -763 being abundant of repressor binding sites of Cdx A, GATA-2, and SRY was enhanced by CF6 in C2C12 cells, and was greater in TG fibroblasts than in WT cells. Reduced autolysozome, assessed by immunofluorescence microscopy as merge of LC3II and lysosome, and LC3 II with increased p62 protein were detected in the TG organs. All of them were reappeared by either administration of amiloride or extracellular acidification. Exposure of endothelial cells to CF6 increased senescence markers and developed the senescence-associated secretory phenotype.
Conclusions: CF6 induces intracellular acidosis by promoting proton import and may be related to reduced autophagy, cellular senescence, and aging in mice.
- © 2013 by American Heart Association, Inc.