engleski

NME6 expression and subcellular localization in human tumor cell lines

NME6 is a member of the nucleoside diphosphate kinase (NDPK/NME/Nm23) family, enzymes which catalyze the transfer of gamma phosphate from nucleoside triphosphates to nucleoside diphosphates. The family has sparked considerable interest from the early nineties after the discovery of tumor metastasis regulation activity of NME1. The Group I members (NME1-NME4) are highly conserved in their amino acid sequence and exhibit NDPK activity, while Group II (NME5-NME9) members display less homology and seem to lack NDPK activity, with a possible exception of NME6. NDPK Group II family members are evolutionary very old, therefore, it is presumed that they participate in one or more basic cellular process. Since little is known about Group II members, we focused our studies on revealing the subcellular localization, quaternary structure and function of Group II human NME6 protein. The expression of NME6 was screened in several human tumor cell lines by Western blot, using specific anti-NME6 antibodies. Subcellular localization has been confirmed by cell fractionation followed by Western blot analysis. Immunofluorescence assays coupled with confocal microscopy has been used to validate results. All human tumor cell lines studied express significant amounts of NME6 protein. Immunofluorescence revealed the colocalization of NME6 with mitochondria, but not with cytoplasm or nucleus. The cell fractionation confirmed the presence of Nme6 in the mitochondrial fraction although human NME6 protein does not possess the mitochondrial targeting sequence. Further studies will be conducted to detect the NME6 potential NDPK activity, quaternary structure, its function in cellular processes and potential role in cancer.

Nme6 protein ; localization

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