DNA damage and expression of checkpoint genes p21(WAF1/CIP1) and 14-3-3 sigma in taurine-deficient cardiomyocytes.
OBJECTIVE
Taurine depletion is associated with development of cardiomyopathy. Further, oxidative stress is advanced as a critical factor mediating the effect of taurine deficiency on target organs. However, the molecular mechanism(s) linking taurine deficiency with the development of cardiomyopathy remains elusive. Since transition between apoptotic degeneration and cell proliferation in stress conditions is regulated at cell cycle checkpoints, we determined the expression of two such genes, namely p21(WAF1/CIP1) and 14-3-3 sigma as well as p53 that are responsible for oxidative stress and DNA damage. We also carried out quantitative determination of DNA damage.


METHODS
Cardiomyocytes from beta-alanine-induced taurine-depleted (TD) rats were used for this investigation. Single- and double-stranded DNA damage was quantified using comet assay analysis. Western blot and two-dimensional polyacrylamide gel electrophoresis with immunoblotting analysis were applied for protein analysis.


RESULTS
Comet assay analysis indicated that the extent of double-stranded DNA damage was greater in TD than in control cardiomyocytes. Whereas only traces of both p53 and p21(WAF1/CIP1) and no detectable expression of 14-3-3 sigma were found in cardiomyocytes of control animals, the TD cardiomyocytes expressed all three genes.


CONCLUSIONS
DNA damage and the consequent up-regulation of checkpoint proteins observed in TD cardiomyocytes indicate the involvement of cell cycle control mechanisms in the effect of taurine deficiency on cardiomyocytes. Single- and double-stranded DNA damage and the consequent arrest of cell proliferation in both G(1) and G(2) phases of the cell cycle induced by checkpoint proteins may trigger the cardiomyopathy that is associated with taurine deficiency.
Golubnitschaja
Olga
O
Department of Radiology, Division of Molecular/Experimental Radiology, University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany. Olga.Golubnitschaja@ukb.uni-bonn.de
Moenkemann
Heike
H
Kim
Kerstin
K
Mozaffari
Mahmood S
MS
D048948:14-3-3 Proteins; D000818:Animals; D014408:Biomarkers, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000096:biosynthesis*; D004249:DNA Damage / Q000502:physiology*; D005092:Exonucleases / Q000096:biosynthesis*; D005095:Exoribonucleases; D006801:Humans; D015151:Immunoblotting; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009363:Neoplasm Proteins; D051381:Rats; D013654:Taurine / Q000172:deficiency / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; C493956:CDKN1A protein, human; C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D009363:Neoplasm Proteins; D013654:Taurine; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human