IGF2BP1 drives atherosclerosis by upregulating ZDHHC5, enhancing NLRP3 inflammasome activation and mitochondrial damage

Atherosclerosis (AS) is a chronic inflammatory disease characterized by the accumulation of lipids and immune cells in arterial walls, with smooth muscle-derived foam cell formation being a critical pathological event. Mitochondrial damage is increasingly recognized as a key contributor to AS pathogenesis, driving cellular dysfunction and inflammation. The NLRP3 inflammasome, a multiprotein complex, plays a central role in initiating and amplifying inflammatory responses by processing pro-inflammatory cytokines like IL-1β and IL-18. However, the precise upstream regulatory mechanisms linking mitochondrial dysfunction, foam cell formation, and NLRP3 activation in vascular smooth muscle cells (VSMCs) remain incompletely understood, representing a significant gap in therapeutic strategies.

Researchers investigated the role of ZDHHC5 in mitochondrial damage and foam cell formation in vascular smooth muscle cells. They used RT-qPCR and Western blot to measure mRNA and protein expression, respectively. Foam cell formation was assessed via ORO and Nile red staining, while mitochondrial integrity was evaluated using Mito tracker Green and Mito Tracker Red probes. Mitochondrial morphology was observed by electron microscopy, and cytoplasmic mtDNA was quantified with a mtDNA release assay. Palmitoylation levels were tested using an Acyl-biotin exchange assay. Protein interactions between ZDHHC5 and NLRP3 were detected by Co-immunoprecipitation (Co-IP), and RNA immunoprecipitation (RIP) and RNA pull down verified the interaction between ZDHHC5 and IGF2BP1. Methylated RNA immunoprecipitation (MeRIP) assessed m6A levels on ZDHHC5. An ApoE-/- mouse model of AS was constructed for in vivo studies, with histological analysis of atherosclerotic lesions and ELISA detection of serum IL-1β and IL-18 levels.

Depletion of NLRP3 significantly reduced damage to mitochondria within smooth muscle-derived foam cells, highlighting its central role. Mechanistically, inhibiting NLRP3 palmitoylation effectively hindered NLRP3 inflammasome activation, suggesting palmitoylation as a critical regulatory step. The study found that ZDHHC5 directly triggered NLRP3 activation by enhancing NLRP3 palmitoylation. Furthermore, ZDHHC5 exacerbated mitochondrial damage through this activation of the NLRP3 inflammasome, establishing a direct link between ZDHHC5, NLRP3, and mitochondrial health. A key upstream regulator was identified: IGF2BP1 enhanced both the stability and expression of ZDHHC5 mRNA in an m6A-dependent manner, revealing a novel epigenetic control mechanism. In vivo, this regulatory axis was confirmed: > IGF2BP1 triggered NLRP3-mediated mitochondrial damage and amplified atherosclerosis progression in ApoE-/- mice by upregulating ZDHHC5. This comprehensive pathway suggests IGF2BP1, ZDHHC5, and NLRP3 could serve as valuable biomarkers for the early detection of atherosclerosis.