Overexpression of Slc30a7/ZnT7 increases the mitochondrial matrix levels of labile Zn2+ and modifies histone modification in hyperinsulinemic cardiomyoblasts |
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| Affiliation: | 1. Department of Biophysics, Ankara University, Faculty of Medicine, Ankara, Turkiye;2. Department of Biophysics, Lokman Hekim University, Faculty of Medicine, Ankara, Turkiye;1. General Surgery Department, Chang Gung Memorial Hospital, Chang Gung University, Keelung, Taiwan, ROC;2. Department of Ophthalmology, Chang Gung Memorial Hospital, Chang Gung University, Keelung, Taiwan, ROC;3. Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, and Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC;4. Institute of Clinical Medicine, Institute of Biopharmaceutical Sciences, and Genome Research Center, Yang-Ming University, Taipei, Taiwan, ROC;5. General Surgery Department, Chang Gung Memorial Hospital, Kwei-Shan, Chang Gung University, Taoyuan, Taiwan, ROC;6. Department of Gastroenterology, Chang Gung Memorial Hospital, Chang Gung University, Keelung, Taiwan, ROC;7. Department of Endocrinology and Metabolism, Chang Gung Memorial Hospital, Chang Gung University, Keelung, Taiwan, ROC;8. Department of Anatomy, College of Medicine, Chang Gung University, Kwei-Shan Taoyuan 333, Taiwan, ROC;9. Faculty of Pharmaceutical Sciences, Teikyo University, Sagamihara, Kanagawa, 252-5195, Japan;10. Boston University School of Medicine, M-1022, 715 Albany Street, Boston, MA 02118, USA;11. Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Kwei-Shan, Taoyuan, Taiwan, ROC;2. Department of Histology and Embryology, Wroclaw Medical University, Poland Chałubińskiego 6a St., 50-368 Wrocław, Poland;1. Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden;2. Chemistry Section, Arrhenius Laboratories, Stockholm University, 106 91 Stockholm, Sweden;3. Department of Chemistry and Biotechnology, Tallinn University of Technology, 19086 Tallinn, Estonia;4. Department of Clinical Physiology, St. Göran Hospital University Unit, 112 81 Stockholm, Sweden;1. Discipline of Nutrition & Metabolism, School of Molecular Bioscience, University of Sydney, NSW 2006, Australia;2. Department of Statistics, Macquarie University, NSW 2109, Australia |
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| Abstract: | BackgroundCellular free Zn2+ concentrations ([Zn2+]) are primarily coordinated by Zn2+-transporters, although their roles are not well established in cardiomyocytes. Since we previously showed the important contribution of a Zn2+-transporter ZnT7 to [Zn2+]i regulation in hyperglycemic cardiomyocytes, here, we aimed to examine a possible regulatory role of ZnT7 not only on [Zn2+]i but also both the mitochondrial-free Zn2+ and/or Ca2+ in cardiomyocytes, focusing on the contribution of its overexpression to the mitochondrial function.MethodsWe mimicked either hyperinsulinemia (by 50-μM palmitic acid, PA-cells, for 24-h) or overexpressed ZnT7 (ZnT7OE-cells) in H9c2 cardiomyoblasts.ResultsOpposite to PA-cells, the [Zn2+]i in ZnT7OE-cells was not different from untreated H9c2-cells. An investigation of immunofluorescence imaging by confocal microscopy demonstrated a ZnT7 localization on the mitochondrial matrix. We demonstrated the ZnT7 localization on the mitochondrial matrix by using immunofluorescence imaging. Later, we determined the mitochondrial levels of [Zn2+]Mit and [Ca2+]Mit by using the Zn2+ and Ca2+ sensitive FRET probe and a Ca2+-sensitive dye Fluo4, respectively. The [Zn2+]Mit was found to increase significantly in ZnT7OE-cells, similar to the PA-cells while no significant changes in the [Ca2+]Mit in these cells. To examine the contribution of ZnT7 overexpression on the mitochondria function, we determined the level of reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP) in these cells in comparison to the PA-cells. There were significantly increased production of ROS and depolarization in MMP and increases in marker proteins of mitochondria-associated apoptosis and autophagy in ZnT7-OE cells, similar to the PA-cells, parallel to increases in K-acetylation. Moreover, we determined significant increases in trimethylation of histone H3 lysine27, H3K27me3, and the mono-methylation of histone H3 lysine36, H3K36 in the ZnT7OE-cells, demonstrating the role of [Zn2+]Mit in epigenetic regulation of cardiomyocytes under hyperinsulinemia through histone modification.ConclusionsOverall, our data have shown an important contribution of high expression of ZnT7-OE, through its buffering and muffling capacity in cardiomyocytes, on the regulation of not only [Zn2+]i but also both [Zn2+]Mit and [Ca2+]Mit affecting mitochondria function, in part, via histone modification. |
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| Keywords: | Zinc transporters Mitochondrial zinc Cardiomyocytes Insulin resistance Reactive oxygen species |
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