Abstract 18469: Snf1-related Kinase (SNRK) Increases Cardiomyocyte Energy and Glycolytic Flux, but Not Aerobic Metabolism, and Reduces Oxidant-induced Cell Death
Background: Sucrose nonfermenting (Snf1)-related kinase (SNRK) is a mammalian homolog of the master metabolic regulator AMP-activated kinase (AMPK). AMPK increases the ATP:AMP ratio by upregulating glycolysis and mitochondrial biogenesis. However, the role of SNRK in metabolism has not been studied. We hypothesized that SNRK regulates cardiomyocyte metabolism through changes in glycolysis and mitochondrial oxygen consumption.
Methods and Results: We first overexpressed SNRK or GFP by adenovirus in neonatal rat cardiomyocytes and found that ATP levels increased by 20.7±7.76% with SNRK vs. GFP, demonstrating that SNRK increases cellular energy. To characterize the metabolic pathways that are regulated by SNRK, we measured glycolysis by extracellular acidification rate (ECAR) and mitochondrial respiration by oxygen consumption rate (OCR) using the Seahorse XF24 extracellular flux analyzer. SNRK increased ECAR by 12.6±6.55% but did not significantly affect OCR at baseline, suggesting an increase in glycolysis but not mitochondrial oxygen consumption. Mitochondrial biogenesis was also unchanged when measured by mitochondrial DNA content using real-time PCR or flow cytometry analysis of the mitochondrial lipid dye nonyl acridine orange. To support the role of SNRK in glycolysis, we measured gene expression by real-time PCR of the glucose transporters GLUT1 and GLUT4 and glycolysis genes hexokinase I and II, which increased 1.7 to 2-fold with SNRK vs. GFP. We also measured glucose uptake with [3H]-2-deoxyglucose, and showed that SNRK increased glucose uptake over GFP by 29.6±14.2%. Finally, to determine whether changes in glucose metabolism by SNRK have an effect on cell survival, we measured cell viability with SNRK transduction after treatment with H2O2. SNRK overexpression increased cell viability (97.9±5.00% vs. 84.2±4.40% with GFP) as measured by propidium iodide exclusion and flow cytometry.
Conclusions: Our results suggest that SNRK increases cardiomyocyte ATP levels through upregulation of glucose uptake and glycolysis to protect against cell death, but unlike AMPK, does not affect mitochondrial respiration. These findings identify SNRK as a unique and novel regulator of cardiomyocyte metabolism and cell death.
- © 2010 by American Heart Association, Inc.