TAL-1/SCL and its partners E47 and LMO2 up-regulate VE-cadherin expression in endothelial cells

Mol Cell Biol. 2007 Apr;27(7):2687-97. doi: 10.1128/MCB.00493-06. Epub 2007 Jan 22.

Abstract

The basic helix-loop-helix TAL-1/SCL essential for hematopoietic development is also required during vascular development for embryonic angiogenesis. We reported that TAL-1 acts positively on postnatal angiogenesis by stimulating endothelial morphogenesis. Here, we investigated the functional consequences of TAL-1 silencing in human primary endothelial cells. We found that TAL-1 knockdown caused the inhibition of in vitro tubulomorphogenesis, which was associated with a dramatic reduction in vascular endothelial cadherin (VE-cadherin) at intercellular junctions. Consistently, silencing of TAL-1 as well as of its cofactors E47 and LMO2 down-regulated VE-cadherin at both the mRNA and the protein level. Endogenous VE-cadherin transcription could be activated in nonendothelial HEK-293 cells by the sole concomitant ectopic expression of TAL-1, E47, and LMO2. Transient transfections in human primary endothelial cells derived from umbilical vein (HUVECs) demonstrated that VE-cadherin promoter activity was dependent on the integrity of a specialized E-box associated with a GATA motif and was maximal with the coexpression of the different components of the TAL-1 complex. Finally, chromatin immunoprecipitation assays showed that TAL-1 and its cofactors occupied the VE-cadherin promoter in HUVECs. Together, these data identify VE-cadherin as a bona fide target gene of the TAL-1 complex in the endothelial lineage, providing a first clue to TAL-1 function in angiogenesis.

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Amino Acid Sequence
  • Antigens, CD / biosynthesis*
  • Antigens, CD / genetics
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors / physiology*
  • Cadherins / biosynthesis*
  • Cadherins / genetics
  • Cells, Cultured
  • Collagen
  • DNA-Binding Proteins / physiology*
  • Drug Combinations
  • Endothelial Cells / metabolism*
  • Endothelial Cells / physiology
  • Endothelium, Vascular / cytology
  • Humans
  • LIM Domain Proteins
  • Laminin
  • Metalloproteins / physiology*
  • Molecular Sequence Data
  • Neovascularization, Physiologic
  • Promoter Regions, Genetic
  • Protein Binding
  • Proteoglycans
  • Proto-Oncogene Proteins / physiology*
  • T-Cell Acute Lymphocytic Leukemia Protein 1
  • TCF Transcription Factors / physiology*
  • Transcription Factor 7-Like 1 Protein
  • Up-Regulation*

Substances

  • Adaptor Proteins, Signal Transducing
  • Antigens, CD
  • Basic Helix-Loop-Helix Transcription Factors
  • Cadherins
  • DNA-Binding Proteins
  • Drug Combinations
  • LIM Domain Proteins
  • LMO2 protein, human
  • Laminin
  • Metalloproteins
  • Proteoglycans
  • Proto-Oncogene Proteins
  • T-Cell Acute Lymphocytic Leukemia Protein 1
  • TCF Transcription Factors
  • TCF7L1 protein, human
  • Transcription Factor 7-Like 1 Protein
  • cadherin 5
  • matrigel
  • TAL1 protein, human
  • Collagen