Transcriptomic and Functional Analyses of Mitochondrial Dysfunction in Pressure Overload-induced Right Ventricular Failure
Background: In complex congenital heart disease patients such as those with tetralogy of Fallot, the right ventricle (RV) is subject to pressure overload, leading to RV hypertrophy and eventually RV failure. The mechanisms that promote the transition from stable RV hypertrophy to RV failure are unknown. We evaluated the role of mitochondrial bioenergetics in the development of RV failure. Methods: We created a murine model of RV pressure overload by pulmonary artery banding and compared with sham-operated controls. Gene expression by RNA-sequencing, oxidative stress, mitochondrial respiration, dynamics, and structure were assessed in pressure overload-induced RV failure. Results: RV failure was characterized by decreased expression of electron transport chain genes and mitochondrial antioxidant genes (aldehyde dehydrogenase 2 and superoxide dismutase 2) and increased expression of oxidant stress markers (heme oxygenase, 4-hydroxynonenal). The activities of all electron transport chain complexes decreased with RV hypertrophy and further with RV failure (oxidative phosphorylation: sham 552.3±43.07 vs. RV hypertrophy 334.3±30.65 vs. RV failure 165.4±36.72 pmol/(sec*ml), p<0.0001). Mitochondrial fission protein DRP1 did not change, while MFF decreased and fusion protein OPA1 decreased. In contrast, transcription of electron transport chain genes increased in the left ventricle of RV failure. Conclusion: Pressure overload-induced RV failure is characterized by decreased transcription and activity of electron transport chain complexes and increased oxidative stress which are associated with decreased energy generation. An improved understanding of the complex processes of energy generation could aid in developing novel therapies to mitigate mitochondrial dysfunction and delay the onset of RV failure. Overall design: The left and right ventricles from FVB mice were used for RNA-sequencing. Control and right ventricular failure samples, achieved through pulmonary artery banding, were compared. N is 4 for each group.