Abstract 13527: Inhibition of With-No-Lysine Kinase Improves Right Ventricular Function by Blunting Excess Protein O-GlcNAcylation

Abstract

Introduction: Pulmonary arterial hypertension (PAH) is caused by obstructive remodeling of the pulmonary arteries which ultimately causes right ventricle (RV) failure and death. Increased expression of the glucose membrane transporters Glut1 and Glut4 occurs in the failing RV, but the upstream regulators of these proteins are unknown. The With-no-Lysine (WNK) kinase-1, a kinase activated in low chloride conditions, promotes expression of Glut1/4 in skeletal muscle, but its regulation in the RV in PAH is unexplored. Furthermore, the relationship between WNK1 and protein O-GlcNAcylation, a glucose based post-translational modification, has not been examined. Methods: Immunoblots quantified the abundance of WNK1, Glut1, Glut4, and total protein O-GlcNAcylation in the RV of control, monocrotaline (MCT) rats, and MCT rats treated with a WNK inhibitor two weeks after MCT injection. Echocardiography and pressure-volume loop analysis assessed RV function and pulmonary vascular disease severity. Results: Treatment with WNK inhibitor improved TAPSE (2.4±0.1 vs 1.8±0.1 mm, p =0.0007), cardiac output (86.0±9.1 vs 52.5±5.6 ml/min, p =0.02), and cardiac output normalized body weight (0.26±0.03 vs 0.15±0.02 ml/min/g, p =0.0032). Importantly, the WNK inhibitor did not alter pulmonary vascular disease severity as there were no differences in pulmonary artery acceleration time (18.2±1.5 vs 14.2±0.9 sec, p =0.22), Ea (0.58±0.07 vs 0.58±0.08 mmHg/μL, p=1.00), or right ventricular systolic pressure (71.8±7.6 vs 72.0±4.0 mmHg, p =1.00) compared to MCT. At the molecular level, WNK1 inhibition decreased expression of WNK1 (MCT: 1.3±0.2 fold increase, MCT-WNK: 3.4±2.2 fold decrease), Glut1 (MCT: 2.7±0.9 fold increase, MCT-WNK: 1.2±0.2 fold increase), Glut4 (MCT: 1.7±0.4 fold increase, MCT-WNK: 1.0±0.2 fold increase), and protein O-GlcNAcylation (MCT: 2.4±0.7 fold increase, MCT-WNK: 1.1±0.1 fold increase). Conclusions: WNK inhibition normalized Glut1/4 expression and protein O-GlcNAcylation in the RV. These molecular changes resulted in improved RV function without a change in pulmonary vascular disease burden.