Collagen XVII, a type II transmembrane protein and epithelial adhesion molecule, can be proteolytically shed from the cell surface to generate a soluble collagen. Here we investigated the release of the ectodomain and identi®ed the enzymes involved. After surface biotinylation of keratinocytes, the ectodomain was detectable in the medium within minutes and remained stable for >48 h. Shedding was enhanced by phorbol esters and inhibited by metalloprotease inhibitors, including hydroxamates and TIMP-3, but not by inhibitors of other protease classes or by TIMP-2. This pro®le implicated MMPs or ADAMs as candidate sheddases. MMP-2, MMP-9 and MT1-MMP were excluded, but TACE, ADAM-10 and ADAM-9 were shown to be expressed in keratinocytes and to be actively involved. Transfection with cDNAs for the three ADAMs resulted in increased shedding and, vice versa, in TACE-de®cient cells shedding was signi®cantly reduced, indicating that transmembrane collagen XVII represents a novel class of substrates for ADAMs. Functionally, release of the ectodomain of collagen XVII from the cell surface was associated with altered keratinocyte motility in vitro.

Inflammation is frequently linked to preterm delivery (PTD). Here, we tested the hypothesis that complement activation plays a role in cervical remodeling and PTD. We studied two mouse models of inflammation-induced PTD. The first model was induced by vaginal administration of lipopolysaccharide (LPS) and the second one by administration of progesterone antagonist RU486. Increased cervical C3 deposition and macrophages infiltration and increased serum C3adesArg and C5adesArg levels were observed in both models when compared to gestational age matched controls. A significant increase in collagen degradation, matrix metalloproteinase 9 (MMP-9) activity and tissue distensibility was observed in the cervix in both models. Mice deficient in complement receptor C5a did not show increased MMP-9 activity and cervical remodeling and did not deliver preterm in response to LPS or RU486, suggesting a role for C5aR in the cervical changes that precede PTD. In vitro studies show that macrophages release MMP-9 in response to C5a. Progesterone diminished the amount of C5aR on the macrophages surface, inhibited the release of MMP-9 and prevented PTD. In addition, macrophages depletion also prevented cervical remodeling and PTD in LPS-treated mice. Our studies show that C5a-C5aR interaction is required for MMP-9 release from macrophages, and the cervical remodeling that leads to PTD. Complement inhibition and supplementation with progesterone may be good therapeutic options to prevent this serious pregnancy complication. Premature birth/delivery (PTD) is one of the most significant causes of perinatal mortality and morbidity in developed countries. Preterm infants suffer morbidities including respiratory distress, intraventricular hemorrhage, and cerebral palsy, among other serious diseases.1 These outcomes can have a life-long impact and more than $25 billion is spent each year to take care of these infants. Investigations to define the causes of PTD remain a challenge in the obstetrical field. Preterm labor is a multistage biochemical and biophysical process, during which changes in the myometrium and the cervix occur.The uterine cervix is a complex organ that undergoes extensive changes through gestation and parturition. These changes are a common first step in preterm parturition.2 As a gatekeeper for pregnancy, the cervix is a structural barrier that keeps the fetus inside the uterus until the end of gestation. Collagens, elastin, proteoglycans, and hyaluronate are responsible for the full tensile strength of the cervix.2 Ripening of the cervix is an important biological and clinical event required for a normal parturition. The process is gradual during pregnancy, with a fast final remodeling of the cervix before parturition. Increased collagen degradation and synthesis, and high activity of collagenases have been observed in the human cervix during final ripening.

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Glomerulonephritis is a major cause of morbidity in patients with systemic lupus erythematosus. Although substantial progress has been made in the identification of pathogenic triggers that result in autoantibody production, little is known about the pathogenesis of aggressive proliferative processes that lead directly to irreversible glomerular damage and compromise of renal function. In this study, we describe a model of polyinosinic: polycytidylic acid-accelerated lupus nephritis in NZB/W mice that is characterized by severe glomerular proliferative lesions with de novo crescent formation, findings that are linked with decreased survival and adverse outcomes in lupus. Proliferative glomerulonephritis was associated with infiltrating kidney macrophages and renal expression of IFNinducible genes, matrix metalloproteinases (MMPs), and growth factors. Crescent formation and renal MMP and growth factor expression were dependent on renal macrophages that expressed Il10, MMPs, osteopontin, and growth factors, including Pdgfc and Hbegf. Infiltrating macrophages and renal MMP expression were induced by type I IFN. These findings reveal a role for type I IFNs and alternatively activated macrophages in aggressive proliferative lesions of lupus nephritis.alternative macrophages | kidney disease | polyinosinic: polycytidylic acid | systemic lupus erythematosus | tissue repair

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Collagen XVII is a transmembrane collagen and the major autoantigen of the autoimmune skin blistering disease bullous pemphigoid. Collagen XVII is proteolytically released from the membrane, and the pathogenic epitope harbors the cleavage site for its ectodomain shedding, suggesting that proteolysis has an important role in regulating the function of collagen XVII in skin homeostasis. Previous studies identified ADAMs 9, 10, and 17 as candidate collagen XVII sheddases and suggested that ADAM17 is a major sheddase. Here we show that ADAM17 only indirectly affects collagen XVII shedding and that ADAMs 9 and 10 are the most prominent collagen XVII sheddases in primary keratinocytes because (a) collagen XVII shedding was not stimulated by phorbol esters, known activators of ADAM17, (b) constitutive and calcium influx-stimulated shedding was sensitive to the ADAM10-selective inhibitor GI254023X and was strongly reduced in Adam10 ؊/؊ cells, (c) there was a 55% decrease in constitutive collagen XVII ectodomain shedding from Adam9 ؊/؊ keratinocytes, and (d) H 2 O 2 enhanced ADAM9 expression and stimulated collagen XVII shedding in skin and keratinocytes of wild type mice but not of Adam9 ؊/؊ mice. We conclude that ADAM9 and ADAM10 can both contribute to collagen XVII shedding in skin with an enhanced relative contribution of ADAM9 in the presence of reactive oxygen species. These results provide critical new insights into the identity and regulation of the major sheddases for collagen XVII in keratinocytes and skin and have implications for the treatment of blistering diseases of the skin.Collagen XVII (also called BP180 or BPAG2) is a hemidesmosomal adhesion component in the skin and mucosa and belongs to the emerging group of collagenous transmembrane proteins (1). This type II oriented transmembrane protein is involved in the molecular pathology of human skin diseases. Mutations in the COL17A1 gene are associated with junctional epidermolysis bullosa, a genetic skin blistering disease (2). Patients with bullous pemphigoid and related autoimmune bullous dermatoses have tissue-bound and circulating autoantibodies targeting collagen XVII (3). Structural and functional changes of collagen XVII play an important role in these diseases, although the molecular pathology is not yet fully understood. The collagen XVII consists of three 180-kDa ␣1 (XVII) chains, each with an intracellular N-terminal domain, a short transmembrane stretch, and a flexible extracellular C-terminal ectodomain with collagenous (Col) 2 subdomains that are interrupted by short non-collagenous (NC) sequences. The human and murine collagen XVII molecules differ in size and in the number of the Col and NC domains. Human collagen XVII consists of 1497 amino acid residues with 15 Col and 16 NC domains, whereas the murine form, which is 86% identical (4), consists of 1433 amino acid residues with 13 Col and 14 NC domains. In humans the extracellular linker domain NC16A between the plasma membrane and the Col15 domain is functionally important because it i...

Collagen XVII (BP180) and its shed ectodomain represent major autoantigens in dermatoses of the pemphigoid group. The 120 kDa ectodomain is constitutively shed from the cell surface by disintegrin-metalloproteinases (ADAMs). Part of it is further processed to a 97 kDa fragment (LABD97), an autoantigen in linear IgA dermatosis (LAD), but the responsible proteinases remain elusive. In this study, we identified the 120 and the 97 kDa ectodomain in blister fluids of bullous pemphigoid patients using new mAbs. As blister fluids contain significant plasmin-like serine protease activity, HaCaT keratinocytes or purified 120 kDa ectodomain were incubated with several human serine proteases. In vitro, only plasmin generated a stable 97 kDa fragment that was also targeted by LAD sera. Characterization of the plasmin-derived 97 kDa fragment with domain-specific collagen XVII antibodies, heparin binding and N-glycosylation studies indicates that the N-terminus is located approximately at AA 515 and the C-terminus N-terminally from AA 1,421. Interestingly, plasmin-derived LABD97 was also generated in the presence of ADAM inhibitors and remained stable over more than 12 hours incubation at 37 degrees C, indicating that this disease relevant collagen XVII fragment can also arise in an ADAM-independent manner through direct action by plasmin.

Gliomedin, which has been implicated as a major player in genesis of the nodes of Ranvier, contains two collagenous domains and an olfactomedin-like domain and belongs to the group of type II transmembrane collagens that includes collagens XIII and XVII and ectodysplasin A. One characteristic of this protein family is that constituent proteins can exist in both transmembrane and soluble forms. Recently, gliomedin expressed at the tips of Schwann cell microvilli was found to bind axonal adhesion molecules neurofascin and NrCAM in interactions essential for Na ؉ -channel clustering at the nodes of Ranvier in myelinating peripheral nerves. Interestingly, exogenously added olfactomedin domain was found to have the same effect as intact gliomedin. Here we analyze the tissue form of gliomedin and demonstrate that the molecule not only exists as full-length gliomedin but also as a soluble form shed from the cell surface in a furin-dependent manner. In addition, gliomedin can be further proteolytically processed by bone morphogenetic protein 1/Tolloid-like enzymes, resulting in release of the olfactomedin domain from the collagen domains. Interestingly, the later cleavage induces formation of higher order, insoluble molecular aggregates that may play important roles in Na ؉ -channel clustering.Collagens and other proteins with collagenous domains constitute the most abundant components of the extracellular matrix. They also play essential roles in development and provision of structural integrity to most tissues and organs and can be divided into nine subgroups (1). Type II-oriented transmembrane collagens are one such subgroup. These play roles in cellmatrix interactions both as integral membrane proteins and as shed forms cleaved from cell surfaces by limited proteolysis (2). Transmembrane collagens XIII (3) and XXV (4) and transmembrane protein ectodysplasin A, which is not formally a collagen but which contains collagenous domains (5), are shed by cleavage at the juxtamembrane consensus sequence (K/R)X n (K/R) (n ϭ 0, 2, 4, 6). Such cleavage is by furin-like proprotein convertases of the S8 family of Kex/subtilisin-related serine endopeptidases (6 -8). In contrast, collagen XVII is not directly cleaved by furin-like convertases. Rather, furin-like convertases activate ADAM (a disintegrin and metalloproteinase) family proteinases that cleave collagen XVII (2, 9).The designation colmedin (collagen repeat plus olfactomedin domain) describes a new type of transmembrane collagen (10) containing an ϳ260-amino acid olfactomedin-like domain at the C terminus. The prototype, olfactomedin, was first identified in the extracellular mucus matrix of the olfactory neuroepithelium of Rana catesbeiana (11,12). With the exception of the sea urchin protein amassin (13), all subsequently characterized olfactomedin-like domain-containing proteins are expressed in neural tissues and seem involved in neural function. Noelin-1 participates in generation of neural crest cells (14, 15), photomedins are expressed in retina (16), tiarin is re...