Shewale, S. | bioRxiv Science

bioRxiv2025

ROR2 drives right ventricular heart failure via disruption of proteostasis

BackgroundNo therapies exist to reverse right ventricular failure (RVF), and the molecular mechanisms that drive RVF remain under studied. We recently reported that the developmentally restricted noncanonical WNT receptor ROR2 is upregulated in human RVF in proportion to severity of disease. Here we test the mechanistic role of ROR2 in RVF pathogenesis. MethodsROR2 was overexpressed or knocked down in neonatal rat ventricular myocytes (NRVMs) and then characterized using confocal microscopy, RNAseq, proteomics, proteostatic functional assays, and pacing to assess contractile properties. The impact of cardiac ROR2 expression was evaluated in mice by AAV9-mediated overexpression and by AAV9-mediated delivery of shRNA to knockdown ROR2 in a pulmonary artery banded pressure overload model of RVF. ROR2-modified mice were evaluated by echocardiography, histology, and RV protein synthesis and proteasome capacity. ResultsIn NRVMs, we find that ROR2 profoundly dysregulates the coordination between protein translation and folding. This imbalance leads to excess protein clearance by the ubiquitin proteasome system (UPS) with dramatic impacts on sarcomere and cytoskeletal structure and function. Inhibiting the UPS or restoring chaperone expression is sufficient to partially rescue ROR2-induced structural and contractile deficits in cardiomyocytes. In mice, forced cardiac ROR2 expression is sufficient to disrupt proteostasis and drive RVF, while conversely ROR2 knockdown partially rescues proteostasis and RV structure and function in a pressure overload model of RVF. ConclusionsIn sum, ROR2 is a key driver of RVF pathogenesis through proteostatic disruption and, thus, provides a promising target to treat RVF.

molecular biology↗

bioRxiv2023

PPP1R3B is a metabolic switch that shifts hepatic energy storage from lipid to glycogen

Obesity is a growing worldwide epidemic that carries numerous metabolic complications including increased risk of type 2 diabetes (T2D), cardiovascular disease (CVD), and non-alcoholic fatty liver disease (NAFLD). Multiple genome-wide association studies (GWAS) have associated the PPP1R3B locus with cardiometabolic traits including fasting glucose and insulin levels (T2D traits), plasma lipids (CVD traits), and indications of hepatic steatosis and liver damage (NAFLD traits)1-5. The PPP1R3B gene encodes the glycogen regulatory protein PPP1R3B (also known as GL) which has an established role in liver glycogen metabolism and plasma glucose homeostasis6,7. The metabolic and NAFLD GWAS single nucleotide polymorphisms (SNPs) in this region, which are all in high linkage disequilibrium, result in increased liver PPP1R3B expression and hepatic glycogen accumulation, but have provided conflicting results on the impacts on hepatic steatosis and liver damage. Here we investigate the consequences of both Ppp1r3b overexpression and deletion in mouse and cell models and find that dysregulated Ppp1r3b expression in either direction promotes metabolic dysfunction and liver injury. Hepatocyte overexpression of Ppp1r3b increases hepatic glycogen storage, prolongs fasting blood glucose levels, and confers protection from hepatic steatosis, but increases plasma ALT in aged animals. Conversely, deletion of hepatocyte Ppp1r3b eliminates hepatic glycogen, causes impaired glucose disposal, and results in hepatic steatosis with age or high sucrose diet. We investigated the metabolic pathways contributing to steatosis and found that Ppp1r3b deletion and diminished glycogenesis diverts the storage of exogenous glucose to hepatic triglycerides (TG), and stored liver lipids are preferentially used for energy during fasting through lipid oxidation and ketogenesis. Further, we interrogated two large human biobank cohorts and found carriers of SNPs associated with increased PPP1R3B expression have increased plasma glucose, decreased hepatic fat, and lower plasma lipids, while putative loss-of-function (pLoF) variant carriers have increased hepatic fat and elevated plasma ketones and lipids, consistent with the results seen in our mouse models. These findings suggest hepatic PPP1R3B serves as a metabolic switch favoring hepatic energy storage as glycogen instead of TG.

molecular biology↗