Role of smooth muscle O-GlcNAcylation on atherosclerotic lesion regression and plaque stability

Atherosclerosis underlies most cardiovascular diseases and is driven by complex cellular and molecular interactions within the vessel wall. While mechanisms promoting lesion formation have been extensively studied, far less is known about pathways that regulate lesion regression and stabilization. O-GlcNAcylation is a nutrient-sensitive post-translational modification that alters protein function and cellular signaling. We previously reported that loss of O-GlcNAc transferase (OGT), a key regulator of O-GlcNAcylation, in smooth muscle cells (SMC) prevents hyperglycemia-induced atherosclerosis. However, whether loss of smooth muscle O-GlcNAcylation affects established lesions once formed remains unclear. To address this, we utilized Apoe-/- mice with conditional SMC-specific Ogt deletion, generated via tamoxifen (tmx)-inducible SMC-restricted Cre driver (Myh11-CreERT2). Five-week-old male Apoe-/-Cretg mice bearing Ogtfl/y or Ogt+/y were fed a Western diet for eight weeks to induce advanced atherosclerotic lesions. At 14-week age, Cre recombination was induced via tmx injection (40mg/kg/day x 5 days) to generate Apoe-/-smOgtKO and Apoe-/-smOgtWT mice. Both groups were then transitioned to standard lab chow for nine weeks to promote lesion regression. At 23-week-age, mice were harvested; aortic roots and aortic vessels were collected for further analysis. Aortic root sections were assessed for plaque size, lipid burden, and collagen content via histological staining and microscopy. In parallel, aortic tissue lysates were used for high-throughput proteomic profiling. Morphometric analysis revealed a significant increase in lipid burden (Oil red O) and collagen content (Masson’s Trichrome) of aortic root lesions in Apoe-/-smOgtKO vs. Apoe-/-smOgtWT mice, while there was no difference in plaque area (H & E) between these mice. Proteomic analysis revealed a total of 4632 proteins, out of which 135 differentially expressed proteins were identified in Apoe-/-smOgtKO aortic vessels, at |log 2 FC| ≥ 1 and p ≤ 0.05 cut-off values. Specifically, top upregulated genes included Chad, P2rx1, Postn (log2FC > 1.5, p < 0.003); top downregulated genes included Itga8, Eln, Epn2 (log2FC ≥ -1.48, p ≤ 0.004). Gene Ontology enrichment analysis of differentially abundant proteins using GO-BP, GO-MF, and GO-CC categories revealed negative enrichment for processes related to cell-cell adhesion and cell-extracellular matrix adhesion in Apoe-/-smOgtKO aortic vessels. Moreover, hallmark analysis revealed significant upregulation of PI3K, AKT, and MTOR signaling pathways, accompanied by suppression of myogenesis in Apoe-/-smOgtKO vessels, using |NES| ≥ ~1.5 and FDR ≤ 0.05 cut-off values. These findings indicate that loss of smooth muscle O-GlcNAcylation during lesion regression increases collagen deposition, coupled with dysregulation of adhesion-related signaling pathways. Overall, our data suggest a novel regulatory role of smooth muscle O-GlcNAcylation in vascular smooth muscle cell signaling and plaque stability, with implications for cardiovascular disease risk and therapy. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.