ProMMP-2: TIMP-1 complexes identified in plasma of healthy individuals.
Activation of MMPs in tissues is an important component of tissue injury. Based on earlier reports that (latent) proMMP-2 is incapable of forming a complex with TIMP-1, we reasoned that the identification of MMP-2:TIMP-1 complexes in blood might serve as a surrogate marker ("smoking gun") of MMP-2 activation in tissues. Using specific antibodies, we developed a sensitive and specific assay to detect MMP-2:TIMP-1 complexes. We were perplexed to find that approximate 40% of plasma specimens from healthy individuals had detectable levels of the MMP-2:TIMP-1 complexes. Employing recombinant TIMP-1 bound Sepharose beads and Western blots, we demonstrated binding between recombinant proMMP-2 and TIMP-1 proteins. Recombinant MMP-2 lacking the catalytic domain also bound to TIMP-1 coated beads. These data are consistent with TIMP-1 binding to the hemopexin or hinge domain of proMMP-2. The explanation for the presence of plasma proMMP-2:TIMP-1 complexes in selected healthy individuals remains to be determined. In contrast to our immunoassay and bead-binding experiments, proMMP-2 failed to bind to immobilized TIMP-1 employing surface plasmon resonance technology. Additional studies are needed to clarify these contrasting results.
Zucker
Stanley
S
Department of Research, Veterans Affairs Medical Center, Northport, New York 11768, USA. s_zucker@yahoo.com
Schmidt
Cathleen E
CE
Dufour
Antoine
A
Kaplan
Robert C
RC
Park
Hyun I
HI
Jiang
Weiping
W
D000328:Adult; D004792:Enzyme Precursors / Q000097:blood*; D005260:Female; D018093:Gelatinases / Q000097:blood*; D006801:Humans; D008297:Male; D045726:Metalloproteases / Q000097:blood*; D008875:Middle Aged; D011485:Protein Binding / Q000502:physiology; D011994:Recombinant Proteins / Q000378:metabolism; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000097:blood*
D004792:Enzyme Precursors; D011994:Recombinant Proteins; D019715:Tissue Inhibitor of Metalloproteinase-1; D045726:Metalloproteases; D018093:Gelatinases; C069860:progelatinase