Abstract Introduction Protein translation dis-regulation is implicated in various diseases, including neurological disorders and cancer. Such dis-regulations can arise from disruptions in translation initiation, elongation, or termination, thereby affecting overall protein synthesis. For example, altered expression of initiation factors has been linked to cancer. However, the role of protein translation dis-regulation in the pathogenesis of pulmonary hypertension (PH) remains understudied and largely unclear. Methods To address this gap, we performed proteomic analysis alongside bulk RNA sequencing of distal pulmonary arteries (DPAs) (2 mm in diameter) from PH calves subjected to 14 days of hypoxia, a condition that induces early yet severe PH. Age-matched healthy calves served as controls. We analyzed activated pathways and genes in PH DPAs at both the protein and transcript levels, followed by a comparative analysis of protein and RNA datasets for each activated pathway. Results Bulk RNA analysis revealed activation of pathways related to cell proliferation, metabolism, hypoxia response, inflammation, and extracellular matrix (ECM) remodeling in PH DPAs. Proteomic analysis of the same PH and control DPAs confirmed activation of these pathways in PH DPAs. However, only a small percentage (5-20%) of genes such as TNC and PLOD1 (two ECM as example) with increased RNA levels showed corresponding increases in protein levels. Conversely, a significant number of genes exhibited increased protein levels without changes in RNA expression. Notably, genes involved in protein translation such as EIF3A and EIF1B showed increased protein levels without corresponding RNA changes. Conclusions Our study reveals that in the early stages of PH, increased protein translation leads to activation of pathways involved in proliferation, hypoxia response, ECM remodeling, and inflammation. Importantly, this protein translation-mediated activation of key PH pathways occurs independently of RNA level increases and involves genes distinct from those with elevated transcription. Thus, our findings provide evidence for the dual roles of gene transcription and protein translation activation in the onset of PH. This abstract is funded by: NHLBI P01HL01498; DOD W81XWH-1910259; DOD W81XWH-2010249
Hu et al. (Fri,) studied this question.