Kaznacheyeva E, Glushankova L, Bugaj V, Zimina O, Skopin A, Alexeenko V, Tsiokas L, Bezprozvanny I, Mozhayeva GN (2007) Suppression of TRPC3 leads to disappearance of store-operated channels and formation of a new type of store-independent channels in A431 cells., J Biol Chem 282 (32) pp. 23655-23662
In most non-excitable cells, calcium (Ca(2+)) release from the inositol 1,4,5-trisphosphate (InsP(3))-sensitive intracellular Ca(2+) stores is coupled to Ca(2+) influx through the plasma membrane Ca(2+) channels whose molecular composition is poorly understood. Several members of mammalian TRP-related protein family have been implicated to both receptor- and store-operated Ca(2+) influx. Here we investigated the role of the native transient receptor potential 3 (TRPC3) homologue in mediating the store- and receptor-operated calcium entry in A431 cells. We show that suppression of TRPC3 protein levels by small interfering RNA (siRNA) leads to a significant reduction in store-operated calcium influx without affecting the receptor-operated calcium influx. With single-channel analysis, we further demonstrate that reduction of TRPC3 levels results in suppression of specific subtype of store-operated calcium channels and activation of store-independent channels. Our data suggest that TRPC3 is required for the formation of functional store-operated channels in A431 cells.
Zimina OA, Glushankova LN, Skopin AY, Alexeenko VA, Vigont VA, Mozhayeva GN, Kaznacheyeva EV (2008) The role of STIM1 protein in the regulation of calcium entry into A431 human epidermoid carcinoma cells, Doklady Biological Sciences 420 (1) pp. 214-217
Kaznacheyeva EV, Glushankova LN, Bugaj VV, Zimina OA, Skopin AY, Alexeenko VA, Bezprozvanny IB, Mozhayeva GN (2007) Role of TRPC3 in the formation of receptor- and store-operated calcium channels in A431 carcinoma cells, Biologicheskie Membrany 24 (1) pp. 87-96
Activation of PLC-linked intracellular signaling cascades in the non-excitable cells evokes the release of calcium ions from the inositol 1,4,5-trisphosphate (InsP3)-sensitive intracellular Ca2+ stores and Ca2+ entry in the cytosol via Ca2+-channels of plasma membrane. The properties and molecular identity of these channels are now under intense investigation. It is speculated that mammalian proteins belonging to the TRP-related family take part in either receptor- and store- dependent entry, though data linking the specific TRP proteins and any endogenous Ca 2+- channel are very scarce. Thus we aimed to study the role of TRPC3 in the formation of receptor- and store- operated calcium entry pathways in A431 cells. Both whole-cell current recordings and fluorescent measurements of intracellular Ca2+ concentration have shown that partial inhibition of TRPC3 expression with small interfering RNAs (siRNA) suppresses the store-dependent Ca2+ entry, but does not affect the receptor-mediated Ca2+ entry. The investigations on the single-channel level revealed that TRPC3 suppression leads to the disappearance of one of the types of store operated Ca2+- channels in the plasma membrane and appearance of a new type of a store-independent channel in it. It might indicate that TRPC3 protein is needed for the functioning of store-dependent channel in A431 cells.
Zhang YH, Cheng H, Alexeenko VA, Dempsey CE, Hancox JC (2010) Characterization of recombinant hERG K+ channel inhibition by the active metabolite of amiodarone desethyl-amiodarone, Journal of Electrocardiology 43 (5) pp. 440-448
The aim of this study was to determine the effects of desethyl-amiodarone (DEA), the major metabolite of the class III antiarrhythmic drug amiodarone, on human ether-à-go-go-related gene (hERG) encoded potassium channel current. Materials and methods: Whole-cell patch clamp recordings were made at 37°C of ionic current (IhERG) carried by recombinant hERG channels expressed in HEK-293 cells. Results: Desethyl-amiodarone inhibited IhERG with a half-maximal inhibitory concentration of approximately 158 nmol/L, compared with approximately 47 nmol/L for amiodarone. The inhibitory action of DEA on IhERG was contingent on channel gating, showing significant time and voltage dependence. Desethyl-amiodarone also produced an approximately -9 mV shift in the voltage dependence of activation of IhERG; however, there was no significant preference for activated over inactivated channels. Conclusions: Because hERG underlies native cardiac "IKr" channels, hERG/IKr inhibition by DEA as well as amiodarone may contribute to the overall effects of amiodarone administration on cardiac repolarization. © 2010 Elsevier Inc. All rights reserved.