The widely expressed extracellular matrix protein SMOC-2 promotes keratinocyte attachment and migration.
SMOC-2 is a recently discovered member of the BM-40/SPARC/osteonectin family of extracellular multidomain proteins of so far unknown function. While we have shown earlier that the homologous protein SMOC-1 is associated with basement membranes, in this study we demonstrate that, in the mouse, SMOC-2 could be detected in a large number of non-basement membrane localizations, often showing a diffuse tissue distribution. A more distinct expression pattern was seen in skin where SMOC-2 is mainly present in the basal layers of the epidermis. Functionally, recombinant SMOC-2 stimulated attachment of primary epidermal cells as well as several epidermal-derived cell lines but had no effect on the attachment of non-epidermal cells. Inhibition experiments using blocking antibodies against individual integrin subunits allowed the identification of alphavbeta6 and alphavbeta1 integrins as important cellular receptors for SMOC-2. Cell attachment as well as the formation of focal adhesions could be attributed to the extracellular calcium-binding domain. The calcium-binding domain also stimulated migration, but not proliferation of keratinocyte-like HaCaT cells. We conclude that SMOC-2, like other members of the BM40/SPARC family, acts as a regulator of cell-matrix interactions.
Maier
Silke
S
Center for Biochemistry, University of Cologne, Joseph-Stelzmann-Str. 52, D-50931 Cologne, Germany.
Paulsson
Mats
M
Hartmann
Ursula
U
D000818:Animals; D000831:Animals, Newborn; D000941:Antigens / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D006168:Guinea Pigs; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D012867:Skin / Q000196:embryology / Q000378:metabolism; D014018:Tissue Distribution
D000941:Antigens; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D011994:Recombinant Proteins; C513851:SMOC-2 protein, mouse; C026908:ubiquitous tissue antigen