Physical interaction between retinoic acid receptor and Sp1: Mechanism for induction of urokinase by retinoic acid

Yasuhiro Suzuki, Jun Shimada, Koichi Shudo, Masatoshi Matsumura, Massimo P. Crippa, Soichi Kojima

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96 Citations (Scopus)


Induction of urokinase plasminogen activator (uPA) by retinoic acid (RA) is the initial event preceding certain subsequent biological changes in vascular endothelial cells. We investigated the molecular mechanism by which RA stimulates the expression of uPA, which lacks a canonical RA receptor (RAR)-responsive element, in bovine and human aortic endothelial cells. Upon stimulation with RA, mRNA levels of RARα and β transiently increased in parallel with the induction of uPA, and this increase was inhibited by cycloheximide. Results of transient transfection of RAR/RXR cDNAs and experiments using specific agonists and antagonists suggested that uPA induction is dependent upon RAR (initially, RARα) with the help of RXRα. Deletion analysis of the uPA promoter suggested that RAR/RXR acts on GC box region within the uPA promoter. This was further supported by inhibition of Sp1 binding to this region. Coimmunoprecipitation studies, glutathione S- transferase pull-down experiment, and mammalian two-hybrid assays suggested a physical interaction between RAR/RXR and Sp1. Furthermore, gel shift studies showed that the binding of Sp1 to the uPA GC box is significantly potentiated in the presence of RARs/RXRs. Finally, Sp1 and RAR/RXR synergistically enhanced the transactivation activity of the uPA promoter. These results suggest that (1) RA induces RARs mainly via RARα and that (2) RAR/RXR physically and functionally interact with Sp1, resulting in a potentiation of uPA transcription.

Original languageEnglish
Pages (from-to)4264-4276
Number of pages13
Issue number12
Publication statusPublished - 1999 Jun 15
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology


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