Novel Loss-of-Function KCNA5 Variants in Pulmonary Arterial Hypertension

Abstract

Reduced expression and/or activity of Kv1.5 channels (encoded byKCNA5) is a common hallmark in human or experimentalpulmonary arterial hypertension (PAH). Likewise, genetic variantsinKCNA5have been found in patients with PAH, but theirfunctional consequences and potential impact on the disease arelargely unknown. Herein, this study aimed to characterize thefunctional consequences of sevenKCNA5variants found in a cohortof patients with PAH. Potassium currents were recorded by patch-clamp technique in HEK293 cells transfected with wild-type ormutant Kv1.5 cDNA. Flow cytometry, Western blot, and confocalmicroscopy techniques were used for measuring protein expressionand cell apoptosis in HEK293 and human pulmonary artery smoothmuscle cells.KCNA5variants (namely, Arg184Pro and Gly384Arg)found in patients with PAH resulted in a clear loss of potassiumchannel function as assessed by electrophysiological and molecular modeling analyses. The Arg184Pro variant also resulted in apronounced reduction of Kv1.5 expression. Transfection withArg184Pro or Gly384Arg variants decreased apoptosis ofhuman pulmonary artery smooth muscle cells compared withthe wild-type cells, demonstrating thatKCNA5dysfunction inboth variants affects cell viability. Thus, in addition toaffecting channel activity, both variants were associated withimpaired apoptosis, a crucial process linked to the disease. Theestimated prevalence of dysfunctionalKCNA5variants in thePAH population analyzed was around 1%. The data indicatethat someKCNA5variants found in patients with PAH havecritical consequences for channel function, supporting the ideathatKCNA5pathogenic variants may be a causative orcontributing factor for PAH.