Modulation of endothelial cell adhesion by hevin, an acidic protein associated with high endothelial venules.
High endothelial venules (HEV) are specialized plump postcapillary venules in lymphoid tissues that support high levels of lymphocyte extravasation from the blood. We have recently identified a novel human transcript, expressed to high levels in HEV, that encodes a secreted, acidic protein closely related to the anti-adhesive extracellular matrix protein known as BM-40, osteonectin, and SPARC (secreted protein acidic and rich in cysteine). Here, we show that this protein, designated hevin, is associated with basal, lateral, and apical surfaces of HEV cells, and unlike MECA-79 antigen, is not expressed on the underlying basement membrane. In contrast to fibronectin or other adhesive extracellular matrix proteins, purified hevin does not support endothelial cell adhesion in vitro. Moreover, addition of soluble exogenous hevin inhibits attachment and spreading of endothelial cells on fibronectin substrates. Hevin-treated cells do not form focal adhesions and exhibit a rounded morphology. Together, these results suggest that hevin is an abundant extracellular protein that modulates high endothelial cell adhesion to the basement membrane.
Girard
J P
JP
Center for Blood Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Springer
T A
TA
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000494:pharmacology / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016326:Extracellular Matrix Proteins; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006023:Glycoproteins / Q000096:biosynthesis* / Q000494:pharmacology / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D008214:Lymphocytes / Q000166:cytology; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D015676:Osteonectin / Q000096:biosynthesis / Q000737:chemistry; D014066:Palatine Tonsil / Q000166:cytology; D011817:Rabbits / Q000276:immunology; D014158:Transcription, Genetic; D014471:Umbilical Veins; D014699:Venules / Q000502:physiology*
D000906:Antibodies; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D009842:Oligopeptides; D015676:Osteonectin; C503126:SPARCL1 protein, human