Loss of CCM3 impairs DLL4-Notch signalling: implication in endothelial angiogenesis and in inherited cerebral cavernous malformations.
Bottom Line: Silencing CCM3 by siRNA stimulated endothelial proliferation, migration and sprouting accompanied by significant downregulation of the core components of Notch signalling including DLL4, Notch4, HEY2 and HES1 and by activation of VEGF and Erk pathways.Treatment with recombinant DLL4 (rhDLL4) restored DLL4 expression and reversed CCM3-silence-mediated impairment of Notch signalling and reduced the ratio of VEGF-R2 to VEGF-R1 expression.CCM3/DLL4-Notch pathway serves as an important signalling for endothelial angiogenesis and is potentially implicated in the pathomechanism of human CCMs.
Affiliation: Department of Neurosurgery, University of Duisburg-Essen, Essen, Germany.Show MeSH
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Mentions: To study the downstream pathway(s) influenced by CCM3-silence-mediated inactivation of DLL4-Notch signalling, we examined the expression of VEGF, VEGF-R1 and VEGF-R2 in different types of cultured endothelial cells. In CCMEC, CCM3 siRNA transfection resulted in an efficient down-regulation of CCM3 level to 30% and 20% of the control at 48 hrs (P < 0.001) and 72 hrs (P < 0.001) respectively. Under these silence conditions, the level of VEGF elevated by 76% (P < 0.01) and 55% (P < 0.01), and more interestingly, the expression of VEGF-R2 increased by 82% and 187% of control at 48 hrs (P < 0.01) and 72 hrs (P < 0.001), respectively, after the transfection. In contrast, the VEGF-R1 mRNA level was moderately down-regulated at 72 hrs after siCCM3 transfection (P < 0.05; Fig. 5A). A similar tendency of change in the expression of VEGF, and VEGF-R1 and VEGF-R2 was observed in CCM3-silenced HUVEC (Fig. 5C), whereas CCM3 silencing in HBMEC resulted in only minor elevation of VEGF-R2 level (Fig. 5B).
Affiliation: Department of Neurosurgery, University of Duisburg-Essen, Essen, Germany.