Abstract 15796: Akt1 Y350f Mutation: A Protective Mechanism Against Pulmonary Hypertension, Suppressing Endothelial-to-Mesenchymal Transition in vivo and in vitro

Abstract

Background: Pulmonary hypertension (PH) is a life-threatening condition characterized by elevated blood pressure in the lungs due to narrowed arteries. Endothelial-to-mesenchymal transition (EndMT) contributes to enhanced proliferation and metabolic changes in the pulmonary arteries of PH patients. Our previous reports have highlighted the role of Akt nitration at tyrosine 350 (Y350) residue in promoting proliferation and metabolic switch in PH models. To investigate the protective potential of inhibiting Akt nitration, we developed a mouse model with a mutation of Akt Y350 to phenylalanine (Y350F), preventing nitration and activation of Akt. Hypothesis: We hypothesized that Akt1 Y350F mutant mice would be protected in preclinical PH models due to inhibited EndMT. Methods: Both mutant Y350F and wild-type Akt1 mice were treated with Sugen5416 (20mg/kg/week i.p.)/hypoxia (10% O2) (Su/Hx) for four weeks to explore pathological mechanisms. Endothelial cells were isolated for in vitro evaluation under EndMT inducers, including Sin-1 chloride and TGF-β1. Results: The wild-type Su/Hx model exhibited vascular remodeling, increased right ventricular systolic pressure (RVSP) (p<0.001), and right ventricular hypertrophy. In contrast, the Akt Y350F mutant model displayed significant protection, with reduced vascular remodeling, pulmonary pressure, and right heart hypertrophy. Akt nitration-induced EndMT markers, TGF-β1 (p<0.05) and TWIST1 (p<0.01), were elevated in wild-type Su/Hx lung tissue. However, the Akt Y350F mutation prevented Akt activation and diminished EndMT markers in the Akt1 Y350F Su/Hx lungs. In isolated cells and lung tissue, induction of EndMT resulted in a progressive PH phenotype, while Akt inhibition exhibited a protective role against PH progression in the Akt Y350F mutant model. Conclusion: Inhibition of Akt nitration through the Y350F mutation restricts vascular remodeling and halts EndMT both in vivo and in vitro. Our findings suggest that strategies targeting Akt nitration could be effective in controlling PH.