Small interfering RNA (siRNA) were transfected into HUVEC using Magnetofetion technology with PolyMAg trasnfection reagent.
As previsouly described in their previous paper (refer to Deleuze et al, Mol Cell Biol. 2007 Apr;27(7):2687-97) the authors used PolyMag transfection reagent from OZ Biosciences to efficiently transfect siRNA into primary endothelial cells, HUVEC.Article reference: PLoS One. 2012;7(7):e40484
Angiopoietin-2 is a direct transcriptional target of TAL1, LYL1 and LMO2 in endothelial cells.Abstract
The two related
basic helix-loop-helix, TAL1 and LYL1, and their cofactor LIM-only-2
protein (LMO2) are present in blood and endothelial cells. While their
crucial role in early hematopoiesis is well established, their function
in endothelial cells and especially in angiogenesis is less understood.
Here, we identified ANGIOPOIETIN-2 (ANG-2), which encodes a major
regulator of angiogenesis, as a direct transcriptional target of TAL1,
LYL1 and LMO2. Knockdown of any of the three transcription factors in
human blood and lymphatic endothelial cells caused ANG-2 mRNA and
protein down-regulation. Transient transfections showed that the full
activity of the ANG-2 promoter required the integrity of a highly
conserved Ebox-GATA composite element. Accordingly, chromatin
immunoprecipitation assays demonstrated that TAL1, LYL1, LMO2 and GATA2
occupied this region of ANG-2 promoter in human endothelial cells.
Furthermore, we showed that LMO2 played a central role in assembling
TAL1-E47, LYL1-LYL1 or/and LYL1-TAL1 dimers with GATA2. The resulting
complexes were able to activate endogenous ANG-2 expression in
endothelial cells as well as in non-endothelial cells. Finally, we
showed that ANG-2 gene activation during angiogenesis concurred with the
up-regulation of TAL1 and LMO2. Altogether, we identified ANG-2 as a
bona fide target gene of LMO2-complexes with TAL1 and/or LYL1,
highlighting a new function of the three hematopoietic factors in the
endothelial lineage.
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