Fisetin, via CKIP-1/REGγ, limits oxidized LDL-induced lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells

Eur J Pharmacol. 2019 Dec 15:865:172748. doi: 10.1016/j.ejphar.2019.172748. Epub 2019 Oct 23.

Abstract

To test the hypothesis that the flavonoid compound, fisetin, protects macrophages from lipid accumulation and senescence through regulation of casein kinase 2-interacting protein-1 (CKIP-1)/REGγ (11S regulatory particles, 28 kDa proteasome activator, proteasome activator subunit 3) signaling. RAW264.7 macrophage cells were exposed to 100 μg/ml oxidized low-density lipoprotein (ox-LDL) with or without 20 μg/ml fisetin for 24 h. Cell viability was detected by CCK-8 after 1 h. Intracellular lipid accumulation was measured using Oil Red O staining. Total cholesterol (TC) and free cholesterol (FC) contents were measured using assay kits, and cell senescence was inferred by β-gal staining. Protein expression levels of CKIP-1, REGγ, organic cation transporter 1 (Oct-1), lectin-like oxidized LDL receptor-1 (LOX-1), tumor suppressor protein p53 (p53), cell cycle regulatory protein p21 (p21), and multiple tumor suppressor-1 (p16) were detected by immunofluorescence and confirmed by Western blot. Stimulating RAW264.7 macrophage cells with 100 μg/ml ox-LDL for 24 h induced the formation of foam cells, increased intracellular lipid accumulation, increased TC and FC content, and promoted cell senescence. Furthermore, cells induced with 100 μg/ml ox-LDL for 24 h showed decreased CKIP-1 and REGγ protein, while the expressions of Oct-1, LOX-1, p53, p21 and p16 were increased. In contrast, treatment with 20 μg/ml fisetin reversed 100 μg/ml ox-LDL effects to increase cell viability, and decrease β-gal staining, intracellular lipid levels and TC and FC levels. These beneficial effects were associated with increased CKIP-1 and REGγ and decreased Oct-1, LOX-1, p53, p21, and p16 protein expression. Results indicated that fisetin limited ox-LDL-mediated lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells. The mechanism underlying these effects may involve regulation of CKIP-1/REGγ signaling.

Keywords: CKIP-1/REGγ signaling; Fisetin; Lipid accumulation; RAW264.7; Senescence.

MeSH terms

  • Animals
  • Autoantigens / metabolism*
  • Carrier Proteins / metabolism*
  • Cellular Senescence / drug effects
  • Flavonoids / pharmacology*
  • Flavonols
  • Foam Cells / drug effects*
  • Foam Cells / metabolism
  • Lipid Metabolism / drug effects
  • Lipoproteins, LDL / metabolism*
  • Mice
  • Proteasome Endopeptidase Complex / metabolism*
  • RAW 264.7 Cells
  • Signal Transduction / drug effects

Substances

  • Autoantigens
  • CKIP-1 protein, mouse
  • Carrier Proteins
  • Flavonoids
  • Flavonols
  • Ki antigen
  • Lipoproteins, LDL
  • oxidized low density lipoprotein
  • Proteasome Endopeptidase Complex
  • fisetin