title: Possible mechanisms of type I collagen-induced vascular tube formation.
abstract: We investigated the effect of type I collagen on endothelial behaviour following its contact with the apical versus basal surface of cultured human endothelial cells. When endothelial cells were plated onto type I collagen they attached via their basal surface and formed a confluent monolayer. However, when type I collagen (100 micrograms/ml) was added directly to the growth medium, so that it made contact with the apical surface of endothelial cells, it induced rapid capillary-like tube formation. Possible mechanisms were assessed using a) polyclonal (anti-VLA-2) and monoclonal (AK7) antibodies to different epitopes on the alpha 2 beta 1 integrin receptor for collagen and b) drugs (chlorpromazine and trifluoperazine) that inhibit protein kinase C activity. Both anti-VLA-2 and AK7 (1-50 micrograms/ml) showed a dose-dependent inhibition of tube formation and cell attachment. At 50 micrograms/ml, anti-VLA-2 completely inhibited tube formation whereas AK7 caused only partial inhibition (less than 50%). By contrast, AK7 was a more potent inhibitor of cell attachment than anti-VLA-2. Both chlorpromazine and trifluoperazine prevented tube formation.
  
  
  CONCLUSIONS
  1) The alpha 2 beta 1 integrin receptor plays a role in both endothelial cell attachment and the induction of tube formation by type I collagen. 2) Protein kinase C may be involved in collagen-induced tube formation.
authors.affiliation: Professorial Department of Rheumatology, Sutton Rheumatism Research Laboratory, Royal North Shore Hospital (RNSH), St Leonards, Sydney, Australia.
authors.forename: C J
authors.initials: CJ
authors.lastname: Jackson
authors.forename: K
authors.initials: K
authors.lastname: Jenkins
authors.forename: L
authors.initials: L
authors.lastname: Schrieber
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D002746:Chlorpromazine / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007074:Immunoglobulin G; D007231:Infant, Newborn; D016023:Integrins / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008833:Microcirculation; D011247:Pregnancy; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012867:Skin / Q000098:blood supply; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology; D014471:Umbilical Veins
chemical_list: D007074:Immunoglobulin G; D016023:Integrins; D014268:Trifluoperazine; D003094:Collagen; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002746:Chlorpromazine