Fibronectin promotes brain capillary endothelial cell survival and proliferation through α5β1 and αvβ3 integrins via MAP kinase signalling

J Wang, R Milner - Journal of neurochemistry, 2006 - Wiley Online Library
J Wang, R Milner
Journal of neurochemistry, 2006Wiley Online Library
We showed previously that blood vessel maturation in the CNS is associated with a
developmental switch in brain capillary endothelial cells (BCEC), from fibronectin signalling
during angiogenesis to laminin signalling in the adult. To investigate the functional
significance of this switch, we have examined the response of BCEC to different extracellular
matrix (ECM) proteins. This showed that BCEC proliferation was significantly promoted by
fibronectin (28.2±4.0%) and by vitronectin (14.8±2.1%) compared with uncoated glass …
Abstract
We showed previously that blood vessel maturation in the CNS is associated with a developmental switch in brain capillary endothelial cells (BCEC), from fibronectin signalling during angiogenesis to laminin signalling in the adult. To investigate the functional significance of this switch, we have examined the response of BCEC to different extracellular matrix (ECM) proteins. This showed that BCEC proliferation was significantly promoted by fibronectin (28.2 ± 4.0%) and by vitronectin (14.8 ± 2.1%) compared with uncoated glass (7.2 ± 0.7%), while BCEC survival was significantly promoted by fibronectin (1130 ± 131 cells), vitronectin (830 ± 63 cells), collagen IV (703 ± 77 cells) and laminin (680 ± 34 cells) compared with the uncoated glass (367 ± 48 cells). Biochemical studies showed that BCEC express a limited repertoire of integrins, including the β1 integrins, α3β1, α5β1 and α6β1, and the αvβ3 integrin. Function‐blocking studies showed that the response to fibronectin was mediated equally by the α5β1 and αvβ3 integrins. Analysis of signalling pathways revealed that fibronectin stimulated activation of the p44/p42 MAP kinase signalling pathway and pharmacological inhibitors of this pathway blocked BCEC proliferation on fibronectin. Taken together, these findings show that fibronectin exerts a strong angiogenic influence on endothelial cells (EC) in the CNS, and that this is mediated through the α5β1 and αvβ3 integrins via MAP kinase signalling. In addition to a fundamental role in development, these findings may also have implications in pathological conditions of the CNS where fibronectin is re‐expressed.
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