ADAMTS-4 and biglycan are expressed at high levels and co-localize to podosomes during endothelial cell tubulogenesis in vitro.
Proteolysis of the extracellular matrix influences vascular growth. We examined the expression of ADAMTS-1, -4, and -5 metalloproteinases and their proteoglycan substrates versican, decorin, and biglycan as human umbilical vein endothelial cells (HUVECs) formed tubes within type I collagen gels in vitro. Tubulogenic and control HUVEC cultures expressed low levels of ADAMTS-1 and -5 mRNAs, but ADAMTS-4 mRNA was relatively abundant and was significantly elevated (as was ADAMTS-4 protein) in tubulogenic cultures versus controls. Immunocytochemistry revealed ADAMTS-4 in f-actin- and cortactin-positive podosome-like puncta in single cells and mature tubes. Tubulogenic and control cultures expressed low levels of versican and decorin mRNAs; however, peak levels of biglycan mRNA were 400- and 16,000-fold that of versican and decorin, respectively. Biglycan mRNA was highest at 3 hr, declined steadily through day 7 and, at 12 hr and beyond, was significantly lower in tubulogenic cultures than in controls. Western blots of extracellular matrix from tubulogenic cultures contained bands corresponding to biglycan and its cleavage products. By immunocytochemistry, biglycan was found in the pericellular matrix surrounding endothelial tubes and in cell-associated puncta that co-localized with ADAMTS-4 and cortactin. Collectively, our results suggest that ADAMTS-4 and its substrate biglycan are involved in tubulogenesis by endothelial cells.
Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama, Japan (MO).
Masanari
M
Obika
Robert B
RB
Vernon
Michel D
MD
Gooden
Kathleen R
KR
Braun
Christina K
CK
Chan
Thomas N
TN
Wight
D051722:ADAM Proteins / Q000235:genetics* / Q000378:metabolism*; D000071121:ADAMTS4 Protein; D000199:Actins / Q000378:metabolism; D058578:Biglycan / Q000378:metabolism*; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D058575:Decorin / Q000378:metabolism; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D011348:Procollagen N-Endopeptidase / Q000235:genetics* / Q000378:metabolism*; D021381:Protein Transport; D013997:Time Factors; D015854:Up-Regulation
D000199:Actins; D058578:Biglycan; D058575:Decorin; D003094:Collagen; D051722:ADAM Proteins; D011348:Procollagen N-Endopeptidase; D000071121:ADAMTS4 Protein; C000603918:ADAMTS4 protein, human
angiogenesis; collagen gel; extracellular matrix; human umbilical vein endothelial cell; matrix metalloproteinases; podosomes; tubulogenesis