Connective tissue growth factor with a novel fibronectin binding site promotes cell adhesion and migration during rat oval cell activation.
Oval cell activation, as part of the regenerative process after liver injury, involves considerable cell-matrix interaction. The matricellular protein, connective tissue growth factor (CTGF), has been shown to be critical for oval cell activation during liver regeneration following N-2-acetylaminofluorene/partial hepatectomy. To understand the mode of action of CTGF during this process, N-terminal CTGF was used as bait to screen a yeast two-hybrid complementary DNA library specific for regenerating livers with massive oval cell presence. Fibronectin (FN), a prominent component of hepatic extracellular matrix (ECM), was found to specifically bind to a new site on CTGF. In addition to module IV, this study showed that module I of CTGF was sufficient for binding to FN in both solid-phase in vitro binding assays and immunoprecipitation. Immunofluorescent staining revealed a dynamic ECM remodeling characterized by an FN-concentrated provisional matrix during oval cell-aided liver regeneration. Abundant CTGF protein was colocalized with FN in the provisional matrix. When expressed as recombinant proteins and immobilized on plastic surfaces, modules I and IV of CTGF were selectively adhesive to thymus cell antigen 1-positive (Thy1(+)) oval cells, stellate cells, and sinusoidal endothelial cells but not to hepatocytes. The adhesion of these two modules on Thy1(+) oval cells required heparan sulfate proteoglycan and integrin alpha(5)beta(1). Recombinant CTGF promoted an integrin alpha(5)beta(1)-dependent migration but not proliferation on Thy1(+) oval cells.


CONCLUSIONS
Modules I and IV enabled the linkage of CTGF to FN and activated hepatic cells. Through these bindings, CTGF on the FN-concentrated provisional matrix promoted cell adhesion and migration, thereby facilitating oval cell activation.
Pi
Liya
L
Department of Pathology Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, USA. lpi@ufl.edu
Ding
Xiaodong
X
Jorgensen
Marda
M
Pan
Jen-Jung
JJ
Oh
Seh-Hoon
SH
Pintilie
Dana
D
Brown
Alicia
A
Song
Wen-Yuan
WY
Petersen
Bryon E
BE
D000818:Animals; D001665:Binding Sites; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D055513:Connective Tissue Growth Factor; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000032:analysis / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D017874:Immediate-Early Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D039081:Integrin alpha5beta1 / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008115:Liver Regeneration / Q000187:drug effects; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D018800:Thy-1 Antigens / Q000032:analysis; D020798:Two-Hybrid System Techniques
C526316:CCN2 protein, rat; D005353:Fibronectins; D019812:Heparan Sulfate Proteoglycans; D017874:Immediate-Early Proteins; D039081:Integrin alpha5beta1; D036341:Intercellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D018800:Thy-1 Antigens; D055513:Connective Tissue Growth Factor