TFAM-dependent and independent dynamics of mtDNA levels in C2C12 myoblasts caused by redox stress

• Published in: Biochimica et biophysica acta Vol. 1760; no. 2; pp. 141 - 150
• Main Authors: Noack, Heiko, Bednarek, Tobias, Heidler, Juliana, Ladig, Roman, Holtz, Jürgen, Szibor, Marten
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2006
• Subjects: Animals; Buthionine Sulfoximine - pharmacology; Cells, Cultured; DNA, Mitochondrial - metabolism; DNA-Binding Proteins - metabolism; Glutathione - physiology; High Mobility Group Proteins - metabolism; Hydrogen Peroxide - pharmacology; Mice; Mitochondria - drug effects; Mitochondria - enzymology; mtDNA; mtTFA; Myoblasts - drug effects; Oxidation-Reduction; Oxidative Stress - physiology; Proliferation; Redox stress; Regeneration; TFAM; Regeneration; TFAM; Proliferation; mtDNA; Redox stress; mtTFA
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2005.12.007

TFAM is an essential protein factor for the initiation of transcription of the mtDNA. It also functions as a packaging factor, which stabilizes the mtDNA pool. To investigate the regulatory role of TFAM for regeneration and proliferation of the mtDNA pool, we exposed the muscle cell line C2C12 to a severe redox stress (H 2O 2) or to a moderate redox stress (GSH depletion), determined the dynamics of the mtDNA levels and correlated this with the TFAM protein levels. H 2O 2 caused a concentration-dependent loss of mtDNA molecules. The mtDNA levels recovered slowly within 3 days after H 2O 2 stress. The TFAM protein was less degraded than the mtDNA indicating an accumulation of TFAM protein per mtDNA after H 2O 2 stress. Overexpression of TFAM did not protect against the mtDNA loss after H 2O 2 stress but shortened the recovery time. GSH depletion led to a proliferation of the mtDNA pool. Although the mtDNA levels increased the TFAM protein levels were unaffected by the GSH depletion. We conclude that the accumulation of the TFAM protein after H 2O 2 stress contributes to the regeneration of the mtDNA pool but that other mechanisms, independent from the TFAM protein amount have to be postulated to explain the proliferation of the mtDNA pool after GSH depletion.