RRR-α-tocopherol decreases the expression of the major scavenger receptor, CD36, in human macrophages via inhibition of tyrosine kinase (Tyk2)

Senthil Kumar Venugopal, Sridevi Devaraj, Ishwarlal Jialal

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

The class B scavenger receptor, CD36, binds to oxidized LDL (OxLDL), is present in atherosclerotic lesions, and is upregulated by OxLDL or AcLDL. Previously we have shown that RRR-α-tocopherol (AT) enrichment of human monocyte-derived macrophages inhibited OxLDL or AcLDL induced CD36 expression. The mechanism by which AT inhibited CD36 expression is not known. In the present study, we explored the mechanism by which AT decreases CD36 expression in human macrophages. Macrophages were enriched with AT (100 μM) or N-acetyl cysteine (NAC, 6 mM) overnight and then incubated with oxLDL or AcLDL for 48 h. The effect of protein kinase C inhibitors, and tyrosine kinase inhibitors on OxLDL or AcLDL-induced CD36 expression was quantitated by flow cytometry. Protein kinase C inhibitors or NAC had no effect while there was a significant inhibition with tyrosine kinase inhibitors (P<0.01). OxLDL or AcLDL significantly increased tyrosine kinase activity which was significantly inhibited by pre-incubation with AT or with tyrosine kinase inhibitors. Western blotting revealed an increase in Tyk2 as well as phosphotyk2 with OxLDL or AcLDL. Immunoprecipitation of CD36 followed by Western blotting with Tyk2 antibodies revealed that Tyk2 was associated with CD36. In conclusion, this study demonstrates an additional direct cellular effect of AT, i.e. inhibition of CD36 expression via inhibition of tyrosine kinase (Tyk2).

Original languageEnglish (US)
Pages (from-to)213-220
Number of pages8
JournalAtherosclerosis
Volume175
Issue number2
DOIs
StatePublished - Aug 2004

Keywords

  • α-tocopherol
  • acetylated LDL
  • AcLDL
  • Bim
  • bisindoleylmaleimide
  • Cal C
  • calphostin C
  • dimethyl sulfoxide
  • DMSO
  • EDTA
  • N-acetyl cysteine
  • NAC
  • oxidized LDL
  • OxLDL
  • p-Tyk2
  • phospho-tyrosine kinase 2
  • RRR-AT
  • scavenger receptors
  • SR
  • Tyk2
  • tyrosine kinase 2

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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