FBXL14 inhibits foam cell formation and atherosclerosis plaque progression by activating the NRF2 signal axis through ubiquitination of DUSP6.

Objectives: Atherosclerosis is characterized by persistent inflammatory condition, leading to various cardiovascular complications. Foam cell formation, resulting from macrophage uptake of oxidized low-density lipoprotein (ox-LDL), contributes significantly to atherosclerosis progression. This study was designed to investigate the involvement of bispecific phosphatase-6 (DUSP6) and its potential regulatory mechanisms in foam cell formation and atherosclerosis.

Methods: We employed THP-1 cells to induce foam cell formation. The lipid droplet accumulation, cholesterol content, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels were evaluated using Oil Red O staining, cholesterol assay, ELISA, and qRT-PCR techniques. We investigated DUSP6 ubiquitination via immunoprecipitation and western blot (WB) analysis. A bioinformatics approach identified FBXL14 as a potential E3 ligase involved in DUSP6 ubiquitination, further confirmed by siRNA and overexpression experiments. The impact of FBXL14 on the NRF2 signaling pathway was assessed using WB analysis.

Results: DUSP6 interference suppressed foam cell formation and inflammatory factor secretion. Upon ox-LDL treatment, DUSP6 underwent deubiquitylation, with FBXL14 emerging as the candidate E3 ligase. FBXL14 overexpression induced DUSP6 ubiquitination, leading to the NRF2 signaling pathway activation. It counteracted with DUSP6 overexpression on foam cell formation and inflammation. In ApoE-/- mice, sh-DUSP6 adenovirus injection mitigated atherosclerotic lesion progression and improved the lipid profile, with increased the proteins expression of NQO1, HO-1, and NRF2 in aortic tissue.

Conclusion: DUSP6 and FBXL14 play vital roles in modulating foam cell formation and inflammatory responses in atherosclerosis. Targeting these molecules could offer therapeutic potential in attenuating atherosclerosis-related complications.

Clinical trial number: Not applicable.