Role of Zinc Transporter ZnT5 In PKC Signaling And Cardiac Cell Survival

Irina Korichneva,Helen Khanova,Nashaba Khan,Camie Doyle

doi:10.1016/j.bpj.2008.12.1350

Irina Korichneva, Helen Khanova + Show 2 more

Open Access

https://doi.org/10.1016/j.bpj.2008.12.1350

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Abstract

Zinc transporter ZnT5 was determined to protect from intracellular zinc overload. We asked whether ZnT5 participates in intracellular signaling and regulation of cell function. Using adult rat cardiomyocytes and cultured atrial cells, HL-1, we investigated interaction of ZnT proteins with protein kinase C (PKC). ZnT5 was found to co-precipitate with PKC isoforms δ and e. Complex formation was zinc-dependent: zinc-depletion with the specific chelator TPEN promoted interaction. PKC activators increased ZnT5 association with PKC e and dissociated PKC δ from the complex. To determine functional significance we assessed translocation of PKC isoforms in HL-1 cells. The cells were transfected with ZnT5cDNA or the mutated dominant negative (DN) form. When ZnT5 expression was modified, localization of both PKC isoforms was altered, particularly pronounced with DN ZnT expression that resulted in disappearance of PKCδ from the Golgi complex. ZnT5 was found to localize in the Golgi in proliferating cultured HL-1 cells but not in adult cardiomyocytes where sarcomeric pattern was observed. Overexpression of ZnT5 enhanced proliferation of HL-1 cells. High demand for ZnT5 in the cells with high rate of proliferation was confirmed in the developing embryos and embryonic bodies. ZnT5 was prevalent in the areas of highly proliferating cells belonging to inner cell mass and not the differentiated ones surrounding basement membrane stained for laminin. Biochemical experiments confirmed that highly proliferating cells in embryonic bodies at stage D2 have higher expression of ZnT5 but not α-actin as compared to D7 stage of development. The expression of α-fetal protein (α-FP) at day 7 indicates differentiation. The data suggest that in addition of controlling zinc homeostasis, ZnT5 zinc transporter plays an important role in signaling. Both functions are likely required for cell survival, proliferation and therefore cardioprotection and embryonic development.

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