CCN2 Modulates Vascular Smooth Muscle Cell Phenotype by Regulating De Novo Lipogenesis Restricted; Files & ToC
Holden, Claire (Fall 2025)
Abstract
Atherosclerosis is characterized as arterial stiffening due to buildup of plaque in the arteries. Atherosclerotic plaque formation is induced by a myriad of factors, and a significant contributor are smooth muscle cells (SMCs). It is well established in the literature that SMCs undergo phenotypic switching, from a more differentiated contractile phenotype to a modulated synthetic proliferative phenotype. These phenotypically modulated cells can transdifferentiate into foam cells, lipid-laden macrophage-like cells that form a significant component of the atherosclerotic plaque. Based on previous work from our lab, we hypothesized that aortas lacking connective tissue growth factor (CTGF)/cellular communication network factor 2 (CCN2) have increased neutral intracellular lipid content. Lipidomics studies were performed to elucidate which lipids SMCs produced. Interestingly, differentially produced lipids in cells lacking CCN2 included palmitate, the direct product of FASN activity, and palmitate-derivatives. In addition, loss of CCN2 in SMCs resulted in dysregulated intracellular lipid structures which we suspect are lipid rafts. To more fully understand the mechanistic components of SMC phenotypic switching, we elucidated the connection between CCN2 and de novo lipogenesis. After further investigation, it was determined that cells lacking CCN2 express an increase in fatty acid synthase (FASN), the rate-limiting enzyme in de novo lipogenesis. These cells also have simultaneous decreased levels of MRTF-A, a known co-activator of the transcriptional machinery for canonical SMC contractile genes. Single cell RNA sequencing CellChat analysis revealed increased signaling between contractile and adipogenic and fibroblast-like SMC phenotypes, and upregulated TWEAK, periostin, ncWnt, TGF-, and COMPLEMENT pathways known to be tightly regulated by lipids. Bulk RNA sequencing studies confirm that a significant loss of CCN2 in human calcified plaques results in downward trends in MRTF-A expression and upward trends in FASN expression compared to control. Single cell RNA sequencing analyses on murine and human data sets confirm that in the context of atherosclerosis, CCN2 expression is altered in SMCs, and that MRTF-A and FASN change as well. AUCell and NicheNET analysis support this conclusion by demonstrating that loss of CCN2 in SMCs increases de novo lipogenesis signature and communication between contractile VSMCs and fibroblast-like SMCs have increased cell-cell signaling and that strength and number of ligand-receptor interactions in CCN2 KO mice was higher in KO compared to WT. We therefore concluded that, collectively, increased FASN activity was responsible for the production of lipids and the lipid-laden phenotype observed with knockdown or loss of CCN2, and that CCN2 modulates SMC phenotype by upregulating de novo lipogenesis through FASN in the context of atherosclerosis.
Table of Contents
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File download under embargo until 12 January 2027 | 2025-11-10 09:22:33 -0500 | File download under embargo until 12 January 2027 |
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