Abstract Body (Do not enter title and authors here): Background:
Pulmonary arterial hypertension (PAH) is a fatal vascular disease marked by mitochondrial dysfunction (MD), vascular proliferation, and right ventricular failure. While mitochondrial enzyme insufficiency has been observed in PAH, the upstream regulators linking metabolic shifts from OxPhos-to-Warburg remain unclear. Our analysis suggests that RBPJ, a transcription factor best known for its role as the effector of Notch signaling, can also act as a mitochondrial energy switch.
Objective:
We investigated whether glucose influx into pulmonary vascular cells triggers the suppression of mitochondrial function through transcriptional mechanisms, initiating MD and driving PAH.
Methods:
We used transgenic mice overexpressing human GLUT4^TG to model glucose-driven metabolic overload. Hemodynamic profiling, histopathology, lung metabolomics, and mitochondrial respiration assays were conducted. Promoter pulldown proteomics and gene silencing were used to identify transcriptional repressors of mitochondrial enzymes.
Results:
GLUT4^TG mice spontaneously developed PAH, as indicated by elevated RV systolic pressure (29.0±2.2;p<0.001), hypertrophy (0.32±0.02;p<0.0001) and vascular remodeling. Pulmonary artery smooth muscle cells (PASMCs) isolated from GLUT4^TG mice exhibited impaired mitochondrial respiration and increased proliferative signaling via Akt/PKC. Metabolic profiling revealed increased glucose uptake in GLUT4^TG mice, leading to glycolysis overload and dysregulation of mitochondrial metabolism. Notably, the lungs showed a significantly reduced expression of the mitochondrial enzymes PDH and complex II (SDHA) (p < 0.001). This reflects findings from a genetic model of MD, NFU1^G206C, which causes a spontaneous PAH phenotype in rats. Promoter pulldown identified the transcription factor RBPJ as a key repressor of PDH and Cx-II. Silencing RBPJ restored PDH and Cx-II and partially rescued mitochondrial function in PASMCs.
Conclusions:
While RBPJ is classically recognized as a mediator of Notch signaling and vascular cell fate, its role in modulating mitochondrial gene expression remains unexplored. Our findings demonstrate, for the first time, that RBPJ directly represses essential mitochondrial enzymes in the pulmonary vasculature under metabolic stress conditions. A new glucose-RBPJ-mitochondrial axis mediates metabolic reprogramming and MD, driving spontaneous PAH in GLUT4^TG. This pathway offers a new therapeutic target to prevent vascular remodeling in PAH.