title: Retinoic acid receptor gamma activates receptor tyrosine kinase Tie1 gene transcription through transcription factor GATA4 in F9 stem cells.
abstract: OBJECTIVE
  The retinoic acid receptors (RARs) alpha, beta2, and gamma regulate specific subsets of target genes during all-trans retinoic acid (RA) induced differentiation of F9 teratocarcinoma stem cells. The Tie1 gene exhibited reduced expression in RA-treated F9 RARgamma-/- cells as compared to wild-type (WT) by microarray analysis. Our goal was to analyze the Tie1 gene, which encodes a surface receptor tyrosine kinase expressed in the hematovascular system.
  
  
  METHODS
  We assessed Tie1, Tie2, Flk1, Runx1, Peg/Mest2, and angiopoietin-1 and 2 mRNA levels and Tie1 promoter activity.
  
  
  RESULTS
  We showed that RARgamma, but not RARalpha or RARbeta2, is required for Tie1 promoter activation by RA. Treatment with a RARgamma selective agonist plus a retinoid X receptor agonist (LGD1069) increased Tie1 mRNA levels by 11- +/- 2.5-fold 48 hours after RA addition in F9 WT, but not in F9 RARgamma-/- cells, by quantitative reverse transcription polymerase chain reaction. Multiple putative GATA elements were identified in the Tie1 proximal promoter. RA increased GATA4 transcripts by 12- +/- 1-fold in F9 WT at 48 hours, but not in F9 RARgamma-/- cells. In addition, transfection of a GATA4 expression vector increased Tie1 promoter/luciferase activity in both RA-treated F9 WT and RARgamma-/- cells. Tie1 promoter deletion analyses indicated that a region of the promoter that possessed multiple GATA sites mediated the RA-associated Tie1 transcriptional increase.
  
  
  CONCLUSIONS
  Our results indicate that GATA4 plays a role in the RA/RARgamma-associated transcriptional activation of the Tie1 promoter. An understanding of RAR specificity in RA signaling should result in insights into hematopoietic stem cell signaling and potentially in improved therapies for several human diseases.
authors.affiliation: Department of Pharmacology, Weill Cornell Medical College, New York NY 10065, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Su
authors.forename: Lorraine J
authors.initials: LJ
authors.lastname: Gudas
mesh_terms: D000818:Animals; D000077610:Bexarotene; D054278:Embryonal Carcinoma Stem Cells / Q000187:drug effects / Q000378:metabolism*; D050991:GATA4 Transcription Factor / Q000187:drug effects / Q000378:metabolism*; D020869:Gene Expression Profiling; D051379:Mice; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D042810:Receptor, TIE-1 / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000819:agonists / Q000187:drug effects / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D000097768:Retinoic Acid Receptor gamma
chemical_list: D000077610:Bexarotene; D050991:GATA4 Transcription Factor; D012333:RNA, Messenger; D042810:Receptor, TIE-1; D018168:Receptors, Retinoic Acid; D013764:Tetrahydronaphthalenes; D014212:Tretinoin; D000097768:Retinoic Acid Receptor gamma