Szerző szerinti böngészés "Yen, Chiao-Hsin"

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    Comparison of the biophysical properties of a wild type K+ channel with its mutant found in cancer cells
    Yen, Chiao-Hsin; Varga, Zoltán; Általános Orvostudományi Kar::Biofizikai és Sejtbiológiai Intézet; DE--Általános Orvostudományi Kar
    In order to survive and proliferate, tumor cells adapt to their microenvironment, which may have non-physiological ion compositions and pH. The adaptation mechanism of the cells can involve mutations of their various proteins, including ion channels. We have collected mutation data from public online databases containing sequences of ion channels obtained from different cancers. By aligning the sequences of related channels, we observed patterns and found the residue positions of the most frequent mutations. R367C in the voltage-gated Kv1.3 K+ channel was one such mutation, which involves an arginine residue in the voltage-sensor of the channel. Kv1.3 is found in multiple cell types but is most abundant in immune cells, such as lymphocytes. Our study aimed to characterize the biophysical properties of this mutant channel and compare it to those of the wild type channel. For this purpose, we generated the R367C mutant by site- directed mutagenesis. We studied the channels by performing whole-cell or outside-out patch-clamp experiments on Chinese Hamster Ovary (CHO) cells transfected with the wild type or mutant channel gene, which were tagged with Green Fluorescent Protein to help identify the successfully transfected cells with a fluorescence microscope. Using various voltage protocols, we studied the activation and inactivation kinetics and voltage sensitivity of the steady-state gating properties of the channels. Our results indicate that the mutation significantly slows both opening kinetics and inactivation kinetics and affects the voltage-sensitivity of Kv1.3 gating. We hypothesize that tumor cells acquire ion channel mutations due to selection pressure, ultimately affecting tumor cell properties and favorably affecting their survival and functions in the tumor microenvironment. With future experiments, we plan to investigate the pH-sensitivity of the mutant channel versus the wild type and determine the functional relevance of the mutation.