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The enzymatic activity of ADAM8 and ADAM9 is not regulated by TIMPs
Augustin Amour1, C Graham Knight, William R English
1School of Biological Sciences, University of East Anglia, Norwich, UK.
Abstract:
The ADAM family of proteases are type I transmembrane proteins with both metalloproteinase and disintegrin containing extracellular domains. ADAMs are implicated in the proteolytic processing of membrane-bound precursors and involved in modulating cell-cell and cell-matrix interactions. ADAM8 (MS2, CD156) has been identified in myeloid and B cells. In this report we demonstrate that soluble ADAM8 is an active metalloprotease in vitro and is able to hydrolyse myelin basic protein and a variety of peptide substrates based on the cleavage sites of membrane-bound cytokines, growth factors and receptors which are known to be processed by metalloproteinases. Interestingly, although ADAM8 was inhibited by a number of peptide analogue hydroxamate inhibitors, it was not inhibited by the tissue inhibitors of metalloproteinases (TIMPs). We also demonstrate that the activity of recombinant soluble ADAM9 (meltrin-gamma, MDC9) lacks inhibition by the TIMPs, but can be inhibited by hydroxamate inhibitors. The lack of TIMP inhibition of ADAM8 and 9 contrasts with other membrane-associated metalloproteinases characterised to date in this respect (ADAM10, 12, 17, and the membrane-type metalloproteinases) which have been implicated in protein processing at the cell surface.
Insights
Soluble ADAM8 and ADAM9 are active metalloproteases. Unlike other metalloproteinases, ADAM8 and ADAM9 are not inhibited by tissue inhibitors of metalloproteinases (TIMPs), suggesting unique regulatory mechanisms for these ADAM proteases.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- ADAM proteases are type I transmembrane proteins involved in proteolytic processing and cell interactions.
- ADAM8 (MS2, CD156) is found in myeloid and B cells.
- ADAM9 (meltrin-gamma, MDC9) is another member of the ADAM family.
Purpose of the Study:
- To investigate the enzymatic activity of soluble ADAM8 and ADAM9.
- To determine the inhibition profiles of ADAM8 and ADAM9 against metalloproteinase inhibitors, including TIMPs.
Main Methods:
- In vitro enzymatic assays using myelin basic protein and peptide substrates.
- Testing inhibition by peptide analogue hydroxamate inhibitors and tissue inhibitors of metalloproteinases (TIMPs).
- Characterization of recombinant soluble ADAM8 and ADAM9 activity.
Main Results:
- Soluble ADAM8 demonstrated active metalloprotease activity in vitro.
- ADAM8 hydrolyzed myelin basic protein and various peptide substrates.
- ADAM8 was inhibited by hydroxamate inhibitors but not by TIMPs.
- Soluble ADAM9 was inhibited by hydroxamate inhibitors but not by TIMPs.
Conclusions:
- ADAM8 and ADAM9 exhibit distinct inhibition profiles compared to other metalloproteinases.
- The lack of TIMP inhibition for ADAM8 and ADAM9 suggests unique regulatory mechanisms.
- These findings contribute to understanding the functional diversity within the ADAM protease family.