With No Lysine Kinase 1 Promotes Right Ventricular Dysfunction Via Glucotoxicity

Objectives Investigate how WNK1 inhibition modulates glucotoxicity, mitochondrial/peroxisomal protein regulation and metabolism, and right ventricular (RV) function in pulmonary arterial hypertension (PAH). Determine how hypochloremia impacts RV function in PAH patients. Background In PAH-induced RV failure, GLUT1/GLUT4 expression is elevated, which increases glucose uptake and glycolytic flux to compensate for mitochondrial dysfunction. However, the resultant consequences of the glucose-mediated post-translational modifications (PTM), protein O-GlcNAcylation/glycation in RV failure are understudied. WNK1, a chloride-sensitive kinase, increases GLUT1/GLUT4 expression in skeletal muscle, but its regulation in RV dysfunction is unexplored. Methods Rats were treated with WNK463 (small molecule WNK inhibitor) or vehicle starting two weeks after monocrotaline injection. Immunoblots quantified protein abundance/PTMs. Mitochondrial/peroxisomal proteomics and global metabolomics evaluated glucose metabolism and mitochondrial/peroxisomal function. Pulmonary vascular and cardiac histology, echocardiography, and pressure-volume loop analysis quantified RV function and PAH severity. Finally, the relationship between hypochloremia, a WNK1-activating state, and RV function was evaluated in 217 PAH patients. Results WNK463 decreased WNK1/GLUT1/GLUT4 expression, normalized glucose metabolite levels, which dampened excess protein O-GlcNAcylation/glycation. Integration of RV mitochondrial/peroxisomal proteomics and metabolomics identified fatty acid oxidation (FAO) as the most dysregulated metabolic pathway. WNK463 enhanced FAO as demonstrated by increased expression of mitochondrial FAO proteins and normalization of RV acylcarnitines. WNK463 reduced glutaminolysis induction and lipotoxicity, two secondary consequences of diminished FAO. WNK463 augmented RV systolic and diastolic function independent of pulmonary vascular disease severity. In PAH patients, hypochloremia resulted in more severe RV dysfunction. Conclusions WNK463 combated RV glucotoxicity and impaired FAO, which directly improved RV function. Highlights ### Competing Interest Statement KWP served on an advisory board for Actelion and Edwards and receives grant funding from United Therapeutics. TT served on an advisory board for Actelion, United Therapeutics, Altavant Sciences, and Aria CV. TT receives research funding for clinical trials from United Therapeutics, Aria CV, Gossimer Bio, and Acceleron. The other authors have declared that no conflict of interest exists. * Aco2 : Aconitase 2 AS160 : 160 kDa substrate of the Akt serine/threonine kinase ATP : Adenosine triphosphate DCA : Dicarboxylic fatty acid DJ-1 : Protein deglycase Ea : Effective arterial elastance Ees : End-systolic elastance ETC : Electron transport chain FAO : Fatty acid oxidation GFAT1 : Glutamine-fructose-6-phosphate transaminase 1 GLO1 : Glyoxalase 1 GLO2 : Glyoxalase 2 GLS : Glutaminase GLUT1 : Glucose transporter 1 GLUT4 : Glucose transporter 4 LV : Left ventricle/ventricular MCT : Monocrotaline MCT V : Monocrotaline-vehicle ME2 : Malic enzyme 2 OGA : O-GlcNAcase OGT : O-linked β- N -acetylglucosamine transferase PAAT : Pulmonary artery acceleration time PAH : Pulmonary arterial hypertension PPARγ : Peroxisome proliferator-activated receptor gamma PTM : Post-translationally modify/modifications PV : Pressure-volume PVR : Pulmonary vascular resistance RA : Right atrial RV : Right ventricle/ventricular RVEDP : Right ventricular end-diastolic pressure RV-PA : Right ventricular-pulmonary artery RVD : Right ventricular dysfunction RVSP : Right ventricular systolic pressure Sdha : Succinate dehydrogenase complex flavoprotein subunit A Sdhb : Succinate dehydrogenase complex iron sulfur subunit B TAPSE : Tricuspid annular plane systolic excursion Tau/τ : Right ventricular relaxation time TCA : Tricarboxylic acid TNFα : Tumor necrosis factor-α UDP-GlcNAC : Uridine diphosphate N -acetylglucosamine WNK : With No Lysine kinase