Macrophages secrete matrix metalloproteinase 9 covalently linked to the core protein of chondroitin sulphate proteoglycans.
Matrix metalloproteinases (MMPs) secreted from the leukemic macrophage cell-line THP-1 have been investigated. Under serum-free conditions, this cell-line synthesizes and secretes proMMP-9, which was detected in the culture medium as a monomer of 92 kDa, and in dimeric forms, including a homodimer of approximately 225 kDa. In addition, a new heterodimer complex is described, in which proMMP-9 is covalently linked to the core protein of chondroitin sulphate proteoglycan (CSPG) through one or more disulphide bridges. After SDS-PAGE electrophoresis, at least two forms of this complex were detected, a large form in the stacking gel and a smaller form with an estimated size of 300 kDa. When the CS chains were removed by chondroitin ABC lyase treatment, heterodimers of proMMP-9/CSPG core protein of approximately 145, 127 and 109 kDa were found, based on zymography and Western blots. Since as much as 10-15 % of the total proMMP-9 secreted from THP-1 cells was covalently linked to CSPG, this association may have important implications for transport, targetting and regulation of the enzyme activity.
Winberg
J O
JO
Department of Biochemistry Institute of Medical Biology, University of Tromso, Tromso, Norway. janow@fagmed.uit.no
Kolset
S O
SO
Berg
E
E
Uhlin-Hansen
L
L
D015153:Blotting, Western; D019765:Chondroitin ABC Lyase / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000737:chemistry / Q000378:metabolism*; D016895:Culture Media, Serum-Free; D019281:Dimerization; D004220:Disulfides / Q000378:metabolism; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000201:enzymology* / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000737:chemistry / Q000378:metabolism*; D008970:Molecular Weight; D011485:Protein Binding; D021381:Protein Transport; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D033921:Vesicular Transport Proteins
D011508:Chondroitin Sulfate Proteoglycans; D016895:Culture Media, Serum-Free; D004220:Disulfides; D004792:Enzyme Precursors; D011509:Proteoglycans; D033921:Vesicular Transport Proteins; C075430:serglycin; D020780:Matrix Metalloproteinase 9; D019765:Chondroitin ABC Lyase