Targeting Epsins to Inhibit FGF Signaling while Potentiating TGF-β Signaling Constrains Endothelial-to-Mesenchymal-Transition in Atherosclerosis

Abstract

Epsin endocytic adaptor proteins are implicated in the progression of atherosclerosis, however the underlying molecular mechanisms have not yet been fully defined. In this study, we determined how epsins enhance endothelial-to-mesenchymal transition (EndoMT) in atherosclerosis and assessed the efficacy of a therapeutic peptide in a preclinical model of this disease. Using single cell RNA sequencing combined with molecular, cellular and biochemical analyses, we investigated the role of epsins in stimulating EndoMT using knockout mouse models. The therapeutic efficacy of a synthetic peptide targeting atherosclerotic plaques was then assessed in ApoE knockout mice. Single cell RNA sequencing and lineage tracing revealed that epsins 1 and 2 promote EndoMT and the loss of endothelial epsins inhibits EndoMT marker expression as well as transforming growth factor-beta signaling in vitro and in atherosclerotic mice, which is associated with smaller lesions in the ApoE knockout mouse model. Mechanistically, the loss of endothelial cell epsins results in increased fibroblast growth factor receptor 1 (FGFR1) expression that inhibits TGF-beta signaling and EndoMT . Epsins directly bind ubiquitinated FGFR1 through their ubiquitin-interacting motif (UIM), which results in endocytosis and degradation of this receptor complex. Consequently administration of a synthetic UIM containing peptide (API) significantly attenuates EndoMT and progression of atherosclerosis. We conclude that epsins potentiate EndoMT during atherogenesis by increasing TGF-beta signaling through FGFR1 internalization and degradation. Inhibition of EndoMT by reducing the epsin-FGFR1 interaction with a therapeutic peptide may represent a novel treatment strategy for atherosclerosis.