Abstract 199: Urocortin Promotes Cell Survival of HL-1 Cells Undergoing Serum-Starvation Inducing Overexpression of MondoA, A Novel Broad Spectrum Activator of Glycolysis
Background: Urocortin is a 40 amino acid peptide involved in cardioprotection and stress coping response mechanisms. A novel basic helix-loop-helix-leucine zipper transcription factor, MondoA, has been recently identified as an activator of a broad spectrum of glycolytic enzymes, including hexokinase II.
Aim: To verify whether urocortin promotes cell survival during starvation and, if so, to investigate the role of MondoA in urocortin-mediated pro-survival activity.
Methods and Results: Overnight serum-starvation (OSS) of HL-1 cells increased apoptotic cell death (quantified by TUNEL staining) by 1.7-fold over full serum controls (FSC) and dramatically reduced ATP reservoir (quantified by bioluminometric assay) to 38%±4.2 of FSC. Incubation of HL-1 cells with 10 nM Ucn for 15 and 60 minutes before OSS reduced myocyte apoptosis by 46.3%±3.2 and 59.2%±4.4, respectively. In addition, 15 and 60 minute incubation with Ucn induced upregulation of MondoA (134.8% and 119.1%, respectively, vs untreated OSS cells), though not of MondoB/ChREBP, a paralog from the same transcription factor family. MondoA induction paralleled overexpression (96.7% and 76.7%, respectively, vs untreated OSS cells) of hexokinase II, a MondoA target enzyme, catalyzing the first step in glycolysis. Ucn-induced up-regulation of MondoA and hexokinase II was documented not only at the protein level by Western blot analysis, but also at the mRNA level by RT-PCR. The concurrent induction of MondoA and hexokinase II paralleled a dramatic improvement in ATP reservoir (81%±5.8 of FSC; >2-fold increase vs OSS cells), which was utterly abolished by expression of a dominant-negative mutant of MondoA in transfected HL-1 cells.
Conclusions: We report for the first time that short-term treatment with Ucn induces overexpression of MondoA, a transcription activator, and hexokinase II, a target glycolytic enzyme, both at the mRNA and protein level. Concurrent induction of MondoA and hexokinase II significantly improved bioenergetics of HL-1 cells exposed to OSS, promoting cell survival.
- © 2010 by American Heart Association, Inc.