Potassium channel subfamily K member 3 (KCNK3), encoded by the KCNK3 gene, is part of the two‐pore domain potassium channel family, constitutively active at resting membrane potentials in excitable cells, including smooth muscle and cardiac cells. Several physiological and pharmacological mediators, such as intracellular signalling pathways, extracellular pH, hypoxia and anaesthetics, regulate KCNK3 channel function. Recent studies show that modulation of KCNK3 channel expression and function strongly influences pulmonary vascular cell and cardiomyocyte function. The altered activity of KCNK3 in pathological situations such as atrial fibrillation, pulmonary arterial hypertension and right ventricular dysfunction demonstrates the crucial role of KCNK3 in cardiovascular homeostasis. Furthermore, loss of function variants of KCNK3 have been identified in patients suffering from pulmonary arterial hypertension and atrial fibrillation. This review focuses on current knowledge of the role of the KCNK3 channel in pulmonary circulation and the heart, in healthy and pathological conditions. image

Pulmonary arterial hypertension (PAH) is severe cardiopulmonary disease that may be triggered by exposure to drugs such as dasatinib or facilitated by genetic predispositions. The incidence of dasatinib-associated PAH is estimated at 0.45%, suggesting individual predispositions. The mechanisms of dasatinib-associated PAH are still incomplete. We discovered a KCNK3 gene (coding for outward K+ channel) variant in a patient with dasatinib-associated PAH, and we investigated the impact of this variant on KCNK3 function. Additionally, we assessed the effects of dasatinib exposure on KCNK3 expression. In control-human in pulmonary arterial smooth muscle cells (hPASMCs) and pulmonary endothelial cells (hPECs), we evaluated the consequence of KCNK3 knockdown on cell migration, mitochondrial membrane potential, ATP production, and in vitro tube formation. Using mass spectrometry, we determined the KCNK3 interactome. Patch-clamp revealed that the KCNK3 variant represents a loss-of-function variant. Dasatinib contributed to pulmonary artery constriction by decreasing KCNK3 function and expression. In control-hPASMCs, KCNK3 knockdown promotes mitochondrial membrane depolarization and glycolytic shift. Dasatinib exposure or KCNK3 knockdown reduced the number of caveolae in hPECs. Moreover, KCNK3 knockdown in control-hPECs reduced migration, proliferation, and in vitro tubulogenesis. Using proximity labeling and mass spectrometry, we identified the KCNK3 interactome, revealing that KCNK3 interacts with various proteins across different cellular compartments. We identified a novel pathogenic variant in the KCNK3 and showed that dasatinib downregulates KCNK3, emphasizing the relationship between dasatinib-associated PAH and KCNK3 dysfunction. We demonstrated that loss of KCNK3-dependent signaling contributes to endothelial dysfunction in PAH and glycolytic switch of hPASMCs.

BACKGROUND: Pulmonary hypertension is a severe disease with high mortality rates due to right ventricular (RV) failure. The molecular and cellular processes involved in RV remodeling, including Ca ²⁺ handling, remain elusive due to the lack of relevant animal models. In this study, we aim to understand better the pathophysiological mechanisms involved in RV failure. METHODS: We used the chronic thromboembolic pulmonary hypertension (CTEPH) pig model, which leads to progressive RV hypertrophy and dysfunction. Cellular, molecular unbiased global transcriptional profiling and biochemical analyses were performed on RV cardiomyocytes from CTEPH and Sham-operated pigs. RESULTS: CTEPH pigs replicated the hemodynamics and histological changes of human CTEPH features. Transcriptome analysis in Sham and CTEPH pigs revealed molecular RV remodeling close to human patients with pulmonary arterial hypertension with decompensated RV function and notably identified changes in genes involved in Ca ²⁺ signaling. At the cellular level, CTEPH myocytes presented reduced L-type Ca ²⁺ current in association with reduced mRNA of CACNA1C . Furthermore, CTEPH myocytes showed lower [Ca ²⁺ ] _i transients, decreased sarcoplasmic reticulum Ca ²⁺ content, and decreased cell shortening, related to reduced SERCA2a (Sarco/endoplasmic reticulum Ca ²⁺ -ATPase isoform 2a) protein expression. Moreover, CTEPH cardiomyocytes exhibited reduced Ca ²⁺ spark occurrence, which relied on smaller RyR2 (ryanodine receptor 2) clusters and T-tubule disorganization. Finally, these alterations in Ca ²⁺ homeostasis were also associated with an increased store-operated Ca ²⁺ entry and the de novo expression of the Ca ²⁺ sensor protein STIM1L (stromal interaction molecule 1 long isoform) in CTEPH myocytes as well as in RV from human patients with pulmonary arterial hypertension. CONCLUSIONS: Our data reveal cellular Ca ²⁺ cycling remodeling that participates in the pathogenesis of RV dysfunction and may constitute therapeutic targets to limit the development of RV dysfunction.

Pulmonary arterial hypertension (PAH) is a chronic disorder characterized by excessive pulmonary vascular remodeling, leading to elevated pulmonary vascular resistance and right ventricle (RV) overload and failure. MicroRNA-146a (miR-146a) promotes vascular smooth muscle cell proliferation and vascular neointimal hyperplasia, both hallmarks of PAH. This study aimed to investigate the effects of miR-146a through pharmacological or genetic inhibition on experimental PAH and RV pressure overload animal models. Additionally, we examined the overexpression of miR-146a on human pulmonary artery smooth muscle cells (hPASMCs). Here, we showed that miR-146a genic expression was increased in the lungs of patients with PAH and the plasma of monocrotaline (MCT) rats. Interestingly, genetic ablation of miR-146a improved RV hypertrophy and systolic pressures in Sugen 5415/hypoxia (SuHx) and pulmonary arterial banding (PAB) mice. Pharmacological inhibition of miR-146a improved RV remodeling in PAB-wild type mice and MCT rats, and enhanced exercise capacity in MCT rats. However, overexpression of miR-146a did not affect proliferation, migration, and apoptosis in control-hPASMCs. Our findings show that miR-146a may play a significant role in RV function and remodeling, representing a promising therapeutic target for RV hypertrophy and, consequently, PAH.

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary arterial hypertension (PAH) occurring in a heritable form (hPVOD) due to biallelic inactivating mutations of EIF2AK4 (encoding GCN2, general control nonderepressible 2) or in a sporadic form in older age (sPVOD), following exposure to chemotherapy or organic solvents. In contrast to PAH, PVOD is characterized by a particular remodeling of the pulmonary venous system and the obliteration of small pulmonary veins by fibrous intimal thickening and patchy capillary proliferation. The pathobiological knowledge of PVOD is poor, explaining the absence of medical therapy for PVOD. Lung transplantation remains the only therapy for eligible PVOD patients. As we recently demonstrated, respiratory diseases, chronic obstructive pulmonary disease, or cystic fibrosis exhibit lipointoxication signatures characterized by excessive levels of saturated phospholipids contributing to the pathological features of these diseases, including endoplasmic reticulum stress, pro-inflammatory cytokines production, and bronchoconstriction. In this study, we investigated and compared the clinical data and lung lipid signature of control (10 patients), idiopathic PAH (7 patients), heritable PAH (9 BMPR2 mutations carriers), hPVOD (10 EIF2AK4 mutation carriers), and sPVOD (6 non-carriers) subjects. Mass spectrometry analyses demonstrated lung lipointoxication only in hPVOD patients, characterized by an increased abundance of saturated phosphatidylcholine (PC) at the expense of the polyunsaturated species in the lungs of hPVOD patients. The present data suggest that lipointoxication could be a potential player in the etiology of PVOD.