Tuncay 2018 MiP2018
Zinc is an essential element in human body regulating many physiological processes. It is involved in DNA and protein synthesis, apoptosis and cardiac contractility. We hypothesized that Zn2+ transporter ZIP7 Zip7 localize not only into SER but also mitochondria affect the sarco(endo)plasmic reticulum S(E)R-mitochondria coupling, and thereby contribute to cellular Zn2+-muffling between S(E)R-mitochondria in hyperglycemic H9c2 cells. We found that ZIP7 is highly expressing in cardiomyocytes and H9c2 cells. We first observed subcellular localization of ZIP7 in mitochondria by using fluorescence technique or biochemical analysis in H9c2 cells. We incubated the H9c2 cells with 25mM glucose for 24h (HG). By using recombinant-targeted Förster resonance energy transfer sensors, we showed that HG induced a marked redistribution of cellular free Zn2+, increasing cytosolic and mitochondrial free Zn2+ and lowering free Zn2+ in the S(E)R. On the other hand, HG caused significant increase of ZIP7 protein level both in S(E)R and mitochondria. Deletion of ZIP7 prevented changes of S(E)R and mitochondrial and intracellular free Zn2+ in HG group. Determine the role of ZIP7 on sarco(endo)plasmic reticulum-mitochondria coupling and apoptosis, we measured mitofusin-protein Mfn-1/2, a mitochondrial ﬁssion protein, Fis-1, which is also a bridge proteins between mitochondria-S(E)R interface, and another bridge proteins between mitochondria-S(E)R interface, Bap31 and apoptosis markers BCL2 and Bax in H9c2 cells. We found the expression levels of Mfn-1/2 and Fis-1 in ZIP7 included cells were markedly high while the Bap31 expression level was dramatically decreased in HG-H9c2 cells. ZIP7 silenced cells slightly prevented these changes. Overall, this study provides an important description about the role of ZIP7, localized to both mitochondria and S(E)R and contribute to cellular Zn2+-muffling between cellular-compartments in HG or hypertrophic cardiomyocytes via affecting S(E)R-mitochondria coupling. Any alteration in this axis and/or cellular [Zn2+] may provide new insight for prevention/therapy of HF in diabetes and/or hypertrophy.
Organism: Rat Tissue;cell: Heart
Regulation: Ion;substrate transport
- Dept Biophysics, Ankara Univ, Fac Medicine, Turkey. - [email protected]
This project is supported by TUBITAK SBAG-216S979.