[The Function of Potassium Channel in KCNQ2 G271V Mutants of Benign Familial Neonatal Convulsions].

ABSTRACT

OBJECTIVE: To determine the function of potassium channel in KCNQ2 G271V mutants of benign familial neonatal convulsions. METHODS: HEK293 cells were transfected with pcDNA3-WT-KCNQ2 and / or pcDNA3-G271V-KCNQ2 and pcDNA3-WT-KCNQ3. The potassium channel function of G271V mutants was assessed using the whole cell patch clamp technique. RESULTS: G271V mutants did not show currents in the transfected HEK cells, inducing large depolarizing shift of the conductance voltage relationship and slowing down the current activation kinetics. The required current density was (2.47±0.41) pA/pF (n=12) for the expression of G271V, and whereas (20.53±2.51) pA/pF (n=10,P<0.001) for Kv7.2. G271V mutants abolished currents in the homomeric channel. Kv7.2/Kv7.3 induced robust current was (123.68±15.21) pA/pF (n=15) and Kv7.2/G271V/Kv7.3 (42.71±6.27) pA/pF (n=10), G271V/Kv7.3 induced almost no current (3.74±0.76) pA/pF (n=10,P<0.05), resulting in about 50% reduction of currents in Kv7.2/G271V/Kv7.3 in the heteromultimeric condition. CONCLUSIONS: The G271V channel fails to open potassium currents in response to depolarization, indicating a more severe functional defect of the Kv7 potassium channel.