Transcription suppression of thromboxane receptor gene expression by retinoids in vascular smooth muscle cells

Akira Uruno, Akira Sugawara, Masataka Kudo, Mayumi Sato, Kazunori Sato, Sadayoshi Ito, Kazuhisa Takeuchi

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Thromboxane (TX) A2 induces contraction and proliferation of vascular smooth muscle cells (VSMCs) via its specific membrane TX receptor (TXR), possibly leading to the progression of atherosclerosis. Retinoids, derivatives of vitamin A, have recently been shown to be anti-atherosclerotic in VSMCs. We therefore examined the effects of retinoids on TX-induced cell growth and TXR expression in VSMCs. TX-induced VSMC proliferation assessed by 3H-thymidine incorporation was completely abrogated by all-trans retinoic acid (ATRA) treatment. The expression of TXR mRNA was significantly decreased by treatment either with ATRA or its stereoisomer 9-cis retinoic acid (RA). Transcription activity of the TXR gene promoter was suppressed by treatment with these retinoids, and a study using retinoid receptor-selective agonists demonstrated that retinoic acid receptors (RARs), rather than retinoid X receptors (RXRs), were mainly involved in the transcription suppression. Deletion analyses demonstrated that the suppression was mediated via the -22/-7 GC-box related sequence. Electrophoretic mobility shift assays showed that Sp1, but not RAR and/or RXR, could bind to the element. The formation of the Sp1 -DNA complex was inhibited by co-incubation with RAR, but not by RXR. Taken together, these findings suggest that TXR gene transcription suppression may be mediated by the inhibition of Sp1 binding to the -22/-7 GC-box related sequence by activated RAR, which may result in the inhibition of TX-induced VSMC proliferation. Our study indicates a novel anti-atherosclerotic action of retinoids fin VSMCs.

Original languageEnglish
Pages (from-to)815-821
Number of pages7
JournalHypertension Research
Volume26
Issue number10
DOIs
Publication statusPublished - 2003 Oct

Keywords

  • 9-cis retinoic acid
  • All-trans retinoic acid
  • Retinoic acid receptor
  • Retinoid
  • Retinoid X receptor

ASJC Scopus subject areas

  • Internal Medicine
  • Physiology
  • Cardiology and Cardiovascular Medicine

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