Stretch-inducible expression of the angiogenic factor CCN1 in vascular smooth muscle cells is mediated by Egr-1.
CCN1 is an angiogenic factor that promotes cell adhesion, proliferation, and differentiation. CCN1-deficient mice suffer embryonic death because of vascular defects, demonstrating that CCN1 is required for vessel development. Because mechanical stretch may act as a trigger for vessel development, we investigated the impact of mechanical stretch on the regulatory mechanism of CCN1 expression. Mechanical stretch rapidly enhances CCN1 expression and release in vascular smooth muscle cells (VSMC) in vitro and CCN1 expression in murine aortic segments in vivo. Transfection experiments of VSMC with deletion constructs of the CCN1 promoter revealed the regulatory region responsible for the stretch-induced CCN1 expression in the approximately 200-bp promoter region upstream of the TATA-box containing potential binding sites for early growth response-1 (Egr-1), nuclear factor of activated T-cells and cAMP response element binding protein. Decoy oligonucleotides to Egr-1, but not to nuclear factor of activated T-cells or cAMP response element binding protein, abolished the stretch-induced transcription of CCN1. In addition, mutagenesis of the Egr-1 binding site within the CCN1 promoter completely blunted the stretch-induced activation of the promoter. Furthermore, mechanical stretch induced the expression and DNA-binding activity of Egr-1 in VSMC as demonstrated by Western blot and electromobility shift assay. Moreover, a pressure overload-dependent de novo synthesis of Egr-1 was observed after aortic banding. These findings indicate that mechanical stretch leads to enhanced expression of CCN1 via the mechanosensitive transcription factor Egr-1, suggesting a central role for mechanical stretch in the regulation of CCN1-dependent pro-angiogenic potency.
Grote
Karsten
K
Department of Cardiology and Angiology, Medical School of Hannover, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany. grote.karsten@mh-hannover.de
Bavendiek
Udo
U
Grothusen
Christina
C
Flach
Inna
I
Hilfiker-Kleiner
Denise
D
Drexler
Helmut
H
Schieffer
Bernhard
B
D000818:Animals; D001011:Aorta / Q000378:metabolism; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D055515:Cysteine-Rich Protein 61; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D051766:Early Growth Response Protein 1; D017353:Gene Deletion; D017874:Immediate-Early Proteins / Q000378:metabolism / Q000502:physiology*; D007150:Immunohistochemistry; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009132:Muscles / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D009389:Neovascularization, Pathologic; D009841:Oligonucleotides / Q000737:chemistry; D011312:Pressure; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D015854:Up-Regulation
C491850:CCN1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D055515:Cysteine-Rich Protein 61; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D009841:Oligonucleotides; D014157:Transcription Factors; D008156:Luciferases