Abstract 12626: Coupling Factor 6 Affects Lifespan By Reduced Autophagy Irrespectively Of Blood Pressure
Backgrounds: Autophagy mediates protective effects in organ damage, and its reduction is associated with accelerated aging. We recently identified a circulating peptide coupling factor 6 (CF6) which binds to the molecular rotary motor F1Fo complex at the plasma membrane, resulting in proton import. We investigated whether overexpression of CF6 contributes to reduced autophagy and accelerated aging by intracellular acidosis.
Methods and Results: We generated transgenic mouse overexpressing CF6 by two folds (TG). Intracellular pH measured by 31P-MR spectroscopy was decreased by 0.1 to 0.15 pH unit in the skeletal muscle and the liver (both p<0.05) in TG compared with wild type mice (WT). TG and WT were fed with either normal or high salt diet (each n=10), and autophagy and lifespan were analyzed. Microarray for autophagy-related genes revealed that overexpression of CF6 was associated with decreased Atg8-conjugation (Atg3, 4A, 4C, and 7) and Atg12-conjugation (Atg7 and 16L1) systems in the heart and kidney, respectively. Salt loading in WT decreased autophagy-related genes similarly to overexpression of CF6. Systolic blood pressure was similar between WT and TG under a normal salt diet. It was unchanged in WT but was elevated by 20 mmHg in TG during salt loading. Lifespan was decreased in TG fed with normal and high salt diets (117±7 and 110±17 months, respectively) and WT fed with a high salt diet (107±8 months) compared with WT with a normal salt diet (134±25 months, p<0.05 vs all other groups). In western blot, an increase in LC3 II and p62 was detected in the TG heart and liver, whereas a decrease in LC3 II with increased p62 was in the TG kidney, both suggesting reduced autophagy. Either administration of amiloride at 10-3M or extracellular acidification increased LC3 II and p62 in the WT heart and liver, and decreased LC3 II with increased p62 in the WT kidney. Exposure of the vascular endothelial cells to CF6 at 10-7M for 24 hours increased the cell senescence markers of p16INK4a, RB1, and p53 expression, and developed the senescence-associated secretory phenotype as the increase in IL1A, IL1B, CCL1, CCL3, and IGFBP5.
Conclusions: CF6 induces intracellular acidosis by promoting proton import and may be related to reduced autophagy, cell senescence, and aging in mice.
- © 2012 by American Heart Association, Inc.