title: Identification of novel matrix metalloproteinase-7 (matrilysin) cleavage sites in murine and human Fas ligand.
abstract: Soluble Fas ligand (sFasL) is released from the cell surface by matrix metalloproteinases (MMPs), one of which is MMP-7. We have reported that MMP-7-generated sFasL is pro-apoptotic in both in vitro and in vivo systems. However, there are contradictory reports that the soluble form of FasL is inactive or anti-apoptotic, resulting in significant controversy in the literature. One potential explanation for these discrepancies is that forms of sFasL with different amino-terminal sequences have been demonstrated to have varying activities. Here we report that MMP-7 cleaves murine and human FasL at sites that are distinct from previously reported cleavage sites resulting in production of novel forms of sFasL. Cleavage of FasL by MMP-7 occurs at the leucine residues in the sequence "ELAELR" within the region between the transmembrane and trimerization domains. When this site is unavailable, a more c-terminal site, "SL," is cleaved. MMP-7 differentially processes murine and human FasL since it cleaves human FasL not only at the "ELAELR" site but also at a previously identified site. Additionally, MMP-3, but not MMP-2, was found to have the same cleavage specificity for murine FasL as MMP-7. We conclude that the controversy regarding the biological activity of sFasL may be explained, in part, by the generation of distinct forms of sFasL as a result of cleavage at specific sequences.
authors.affiliation: Department of Cancer Biology, Vanderbilt University, 736 PRB 23rd and Pierce, Nashville, TN 37232-6840, USA.
authors.forename: Tracy
authors.initials: T
authors.lastname: Vargo-Gogola
authors.forename: Howard C
authors.initials: HC
authors.lastname: Crawford
authors.forename: Barbara
authors.initials: B
authors.lastname: Fingleton
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Matrisian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D053222:Fas Ligand Protein; D006801:Humans; D007930:Leucine / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000378:metabolism; D012995:Solubility; D013379:Substrate Specificity
chemical_list: C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D019278:Matrix Metalloproteinase 3; D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2; D007930:Leucine