Introduction: Pulmonary hypertension due to left heart disease (PH-LHD) is aggravated by pulmonary vascular stiffening resulting from extracellular matrix (ECM) remodeling (Kucherenko et al., Nat. Comm. 2023). Here, we investigate how ECM remodeling in PH-LHD promotes endothelial dysfunction, focusing on metabolic reprogramming and mitochondrial (MT) adaptation as a function of the mechanosensitive transcriptional co-activator YAP1, a central mediator of the cellular response to ECM stiffness.
Methods and Results: Decellularized ECM (dECM) was generated from ECM produced by primary pulmonary arterial endothelial cells (PAEC) isolated from PH-LHD and control parients. dECM composition and stiffness were assessed by mass spectrometry and atomic force microscopy. YAP1 activation, PAEC proliferation, and MT function were measured using immunofluorescence (YAP1, Ki67, TOM20, DRP1), MT assays (JC-1, mtSOX), ATP assay, bulk- and single nuclei-RNA sequencing, and gas chromatography-mass spectrometry metabolomics. YAP1 inhibition/silencing was achieved with verteporfin or siRNA, and MT stress was induced by CCCP or paraquat.
dECM derived from PH-LHD had increased stiffness and a higher abundance of fibrillar collagen. Culturing of control PAEC on PH-LHD dECM or stiff matrices resulted in YAP1 activation and enhanced cell proliferation that was reversed by YAP1 inhibition. Transcriptomic analyses revealed upregulation of key YAP1 target genes, such as PDK4 and GLS, which induce a shift from oxidative phosphorylation to glycolytic metabolism that was evident as elevated levels of glycolytic metabolites. YAP1 inhibition in PH-LHD PAEC impaired glycolytic ATP production, decreased MT membrane potential and increased generation of ROS, that was associated with increased MT fission. Induction of MT stress in control PAECs activated YAP1, indicating a reciprocal feedback loop between MT dysfunction and YAP1 activation.
Conclusions: Our findings indicate a critical role for MT dysfunction in the pathogenesis of PH-LHD, with YAP1 acting as critical mediator linking ECM stiffening and metabolic reprogramming to reduce MT stress, thus supporting endothelial survival and proliferation. These responses, however, create a maladaptive feedback loop that exacerbates disease progression. These findings highlight the potential of targeting YAP1 and MT dysfunction as therapeutic strategies for PH-LHD.
Acknowledgements: German Centre for Cardiovascular Research (DZHK), German Research Foundation (DFG), SFB 1470, German Heart Research Foundation (DSHF).
