Biosynthesis of alpha2(IV) and alpha1(IV) chains of collagen IV and interactions with matrix metalloproteinase-9

J Cell Physiol. 1999 Jul;180(1):131-9. doi: 10.1002/(SICI)1097-4652(199907)180:1<131::AID-JCP15>3.0.CO;2-S.


In vitro binding studies with latent matrix metalloproteinase-9 (pro-MMP-9) have revealed the existence of nondisulfide-bonded alpha2(IV) chains on the cell surface capable of forming a high-affinity complex with the enzyme. Here we investigated the biosynthesis and cellular distribution of alpha2(IV) and alpha1(IV) chains in breast epithelial (MCF10A and MDA-MB-231) and fibrosarcoma (HT1080) cells by pulse-chase analysis followed by immunoprecipitation with chain-specific monoclonal antibodies (mAb). These studies showed that whereas the alpha1(IV) chain remained in the intracellular compartment, nondisulfide-bonded alpha2(IV) chains were secreted into the media in a stable form. Consistently, only alpha2(IV) was detected on the cell surface by surface biotinylation or indirect immunofluorescence. In agreement with the pulse-chase analysis, media subjected to co-precipitation experiments with pro-MMP-9 or pro-MMP-9-affinity chromatography followed by immunoblotting with chain-specific mAbs resulted in the detection of alpha2(IV). A preferential secretion of nondisulfide-bonded alpha2(IV) chains was also observed in CHO-K1 cells transiently transfected with full-length mouse alpha2(IV) or alpha (IV) cDNAs. However, a complex of mouse alpha1(IV) with pro-MMP-9 was coprecipitated with exogenous enzyme from lysates of CHO-K1 cells transfected with mouse alpha1(IV), suggesting that under overexpression conditions the enzyme can also interact with the alpha1 (IV) chain. Collectively, these studies further demonstrate the interactions of pro-MMP-9 with collagen IV chains and a unique processing and targeting of nondisulfide-bonded alpha2(IV) chains that may play a role in the surface/matrix association of pro-MMP-9.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal
  • Breast / cytology
  • CHO Cells
  • Cells, Cultured
  • Collagen / analysis
  • Collagen / genetics*
  • Collagen / immunology
  • Collagen Type IV*
  • Collagenases / metabolism*
  • Cricetinae
  • Enzyme Precursors / metabolism
  • Epithelial Cells / chemistry
  • Epithelial Cells / cytology
  • Epitopes / genetics
  • Fluorescent Antibody Technique
  • Gene Expression Regulation, Enzymologic
  • HeLa Cells
  • Humans
  • Matrix Metalloproteinase 9
  • Mice
  • Molecular Sequence Data
  • Peptide Fragments / analysis
  • Peptide Fragments / genetics*
  • Peptide Fragments / immunology
  • Recombinant Proteins / genetics
  • Transfection


  • Antibodies, Monoclonal
  • Collagen Type IV
  • Enzyme Precursors
  • Epitopes
  • Peptide Fragments
  • Recombinant Proteins
  • collagen type IV alpha1 (531-543)
  • Collagen
  • Collagenases
  • Matrix Metalloproteinase 9