Epilysin, a Novel Human Matrix Metalloproteinase (MMP-28) Expressed in Testis and Keratinocytes and in Response to Injury

Abstract

We have cloned a new human matrix metalloproteinase (MMP-28, epilysin) from human keratinocyte and testis cDNA libraries. Like most MMPs, epilysin contains a signal sequence, a prodomain with a PRCGVTD sequence, a zinc-binding catalytic domain with an HEIGHTLGLTH sequence, and a hemopexin-like domain. In addition, epilysin has a furin activation sequence (RRKKR) but has no transmembrane sequence. The exon-intron organization and splicing pattern of epilysin differ from that of other MMP genes. It has only 8 exons, and 5 exons are spliced at sites not used by other MMPs. Another novel feature of epilysin is that exon 4 is alternatively spliced to a transcript that does not encode the N-terminal half of the catalytic domain. Northern hybridization of tissue RNA indicated that epilysin is expressed at high levels in testis and at lower levels in lungs, heart, colon, intestine, and brain. RNase protection assay with various cell lines indicated that epilysin was selectively expressed in keratinocytes. Recombinant epilysin degraded casein in a zymography assay, and its proteolytic activity was inhibited by EDTA and by batimastat, a selective MMP inhibitor. Immunohistochemical staining showed expression of epilysin protein in the basal and suprabasal epidermis of intact skin. In injured skin, prominent staining for epilysin was seen in basal keratinocytes both at and some distance from the wound edge, a pattern that is quite distinct from that of other MMPs expressed during tissue repair. These findings suggest that this new MMP functions in several tissues both in tissue homeostasis and in repair. The matrix metalloproteinases (MMPs)1 compose a family of enzymes that share several common structural features and that function both in the turnover and degradation of extracellular matrix proteins and in the processing, activation, or deactivation of a variety of soluble factors (1). MMPs, or matrixins, are a subgroup of the much larger metalloproteinase superfamily, which also includes astacin and ADAM proteinases, among others. To date 23 different MMPs have been cloned, and additional members continue to be identified (2).To be classified as a matrix metalloproteinase, a protein must have conserved features of two domains, namely the prodomain and the catalytic domain. The prodomain of a typical MMP is about 80 amino acids, and all MMPs, except MMP-23 (3), contain the consensus sequence PRCXXPD. As for all metalloproteinases, the catalytic domain contains an active site Zn 2ϩ that binds three conserved histidines in the sequence HEXXHXXGXXH(S/T)XXXXXXM, which also contains a conserved methionine to the carboxyl side of the zinc-binding site (metzincins) (4). In an inactive state, the conserved cysteine residue in the prodomain provides the fourth coordination site for the catalytic zinc ion. In addition, with the exception of matrilysin (MMP-7), endometase/matrilysin-2 (MMP-26), and MMP-23, MMPs have a hinge region, which is often prolinerich, and a so-called hemopexin-like C-terminal domain (3,5,6). Other domains fou...

Comprehensive profiling and localisation of the matrix metalloproteinases in urothelial carcinoma

“…Collectively, the MMP family can degrade all components of the extracellular matrix and there is significant overlap of substrate specificity between each MMP (Sternlicht and Werb, 2001;Egeblad and Werb, 2002). Many well-established MMPs have a broad proteolytic activity; however, not all MMPs share this propertyrecently isolated members such as MMP-28 appear to have only a single identified substrate, and for others the substrate or signalling pathway is unknown (Lohi et al, 2001).…”

Matrix metalloproteinase‐19 is expressed by proliferating epithelium but disappears with neoplastic dedifferentiation

“…MMPs can be divided into 6 subgroups: interstitial collagenases (MMP-1, MMP-8 and MMP-13), stromelysins (MMP-3, MMP-10, MMP-11 and MMP-12), matrilysins (MMP-7 and MMP-26), type IV collagenases (MMP-2 and MMP-9), membrane-type MMPs (MMP-14, MMP-15, MMP-16, MMP-17, MMP-24 and MMP-25) and others (MMP-19, MMP-23 and MMP-28). [1][2][3] Collagenase-1 (MMP-1), stromelysin-2 (MMP-10) and 92 kDa gelatinase (MMP-9) participate in keratinocyte migration during wound repair as well as in cancer cell migration. 4,5 The role of the novel MMPs (from MMP-19 upward) in skin biology has not been well elucidated.…”

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Overexpression of Tissue Inhibitor of Metalloproteinases-3 in Intestinal and Cutaneous Lesions of Graft-versus-Host Disease

“…Since the early sixties, 21 human members of this enzyme family have been cloned. According to their structure and substrate specificity, MMPs can be grouped into collagenases (MMP-1, -8, and 13), gelatinases (MMP-2 and -9), stromelysins (MMP-3, -10, -11, and -12), membrane-type metalloproteinases (MMP-14, -15, -16, -17, and -24), matrilysins , and other MMPs 3,4). MMPs are regulated mainly at the transcriptional level, and their enzymatic activity can be inhibited by tissue inhibitors of metalloproteinases (TIMP), a protein group that currently comprises four members (TIMP-1, -2, -3, and -4).…”