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: Next, we examined DLL4-Notch signalling in human CCMs. Because of the extremely rare availability, only one human surgical specimen of a CCM3 germline mutation carrier could be obtained during this study. To draw a more convinced comparison between familial and sporadic CCMs, we used six surgical specimens from sporadic CCM as control. RT2-PCR detected around 5-, 38- and 35-fold decrease in CCM3, DLL4 and Notch4 expression, respectively, in the CCM3-deficient cavernous lesion (Mu-CCM3) in comparison with the human sporadic CCMs (Sp-CCM). A dramatic down-regulation of the target gene HEY2 and HES1 was also observed in Mu-CCM3, indicating an impaired DLL4-Notch signalling in familial CCM with germline mutation in CCM3. Interestingly, the level of Notch1 was similarly detected in Mu-CCM3 and in Sp-CCMs (Fig. 3A). These data drawn from CCM patients were entirely consistent with the results obtained from CCM3-silenced HUVEC (Fig. 2A) and CCMEC (Fig. 2D).
Affiliation: Department of Neurosurgery, University of Duisburg-Essen, Essen, Germany.