Molecular characteristics of equine stromelysin and the tissue inhibitor of metalloproteinase 1

Objective-To clone the entire coding sequence of equine matrix metalloprote inase-3 (MMP-3, stromelysin) and tissue inhibitor of metalloproteinase-1 (T IMP-1) and compare their nucleotide and amino acid sequences with those of MMP-3 and TIMP-1 from other species. Samples-Articular cartilage harvested from the joints of 4 foals, 2 yearlin gs, and 3 adult horses. Procedure-A cDNA library was constructed from mRNA extracted from equine ch ondrocytes. The library was screened and clones selected that contained the cDNA for MMP-3 and TIMP-1. The cDNA was sequenced and the nucleotide and d educed amino acid sequences compared with known sequences in other species. Northern blot analysis was performed, using the resulting cDNA clones. Results-An 1803-bp cDNA for MMP-3 including the entire coding sequence of 1 434 bases was cloned and sequenced. A 744-bp cDNA for TIMP-1 including the entire coding sequence of 624 bases was cloned and sequenced. Northern anal ysis revealed MMP-3 to hybridize to a single mRNA species at approximately 2.1 kb. TIMP-1 hybridized to a single mRNA species at approximately 0.8 kb. Conclusions-MMP3 and TIMP-1 were highly homologous to that of other species at the nucleotide and amino acid level although each had unique residues i n part of the peptide that is generally conserved. Clinical Relevance-Understanding the molecular structure of MMP-3 and TIMP- 1 and the availability of their cDNA should allow a more detailed understan ding of their balance in cartilage and the degradative processes in joint d isease.