Publications by authors named "Christoph Becker-Pauly"

84 Publications

Phosphorylation of meprin β controls its cell surface abundance and subsequently diminishes ectodomain shedding.

FASEB J 2021 07;35(7):e21677

Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Kiel, Germany.

Meprin β is a zinc-dependent metalloprotease exhibiting a unique cleavage specificity with strong preference for acidic amino acids at the cleavage site. Proteomic studies revealed a diverse substrate pool of meprin β including the interleukin-6 receptor (IL-6R) and the amyloid precursor protein (APP). Dysregulation of meprin β is often associated with pathological conditions such as chronic inflammation, fibrosis, or Alzheimer's disease (AD). The extracellular regulation of meprin β including interactors, sheddases, and activators has been intensively investigated while intracellular regulation has been barely addressed in the literature. This study aimed to analyze C-terminal phosphorylation of meprin β with regard to cell surface expression and proteolytic activity. By immunoprecipitation of endogenous meprin β from the colon cancer cell line Colo320 and subsequent LC-MS analysis, we identified several phosphorylation sites in its C-terminal region. Here, T694 in the C-terminus of meprin β was the most preferred residue after phorbol 12-myristate 13-acetate (PMA) stimulation. We further demonstrated the role of protein kinase C (PKC) isoforms for meprin β phosphorylation and identified the involvement of PKC-α and PKC-β. As a result of phosphorylation, the meprin β activity at the cell surface is reduced and, consequently, the extent of substrate cleavage is diminished. Our data indicate that this decrease of the surface activity is caused by the internalization and degradation of meprin β.
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http://dx.doi.org/10.1096/fj.202100271RDOI Listing
July 2021

Cell Surface Processing of CD109 by Meprin β Leads to the Release of Soluble Fragments and Reduced Expression on Extracellular Vesicles.

Front Cell Dev Biol 2021 2;9:622390. Epub 2021 Mar 2.

Anatomical Institute, Christian-Albrechts-University Kiel, Kiel, Germany.

Cluster of differentiation 109 (CD109) is a glycosylphosphatidylinositol (GPI)-anchored protein expressed on primitive hematopoietic stem cells, activated platelets, CD4 and CD8 T cells, and keratinocytes. In recent years, CD109 was also associated with different tumor entities and identified as a possible future diagnostic marker linked to reduced patient survival. Also, different cell signaling pathways were proposed as targets for CD109 interference including the TGFβ, JAK-STAT3, YAP/TAZ, and EGFR/AKT/mTOR pathways. Here, we identify the metalloproteinase meprin β to cleave CD109 at the cell surface and thereby induce the release of cleavage fragments of different size. Major cleavage was identified within the bait region of CD109 residing in the middle of the protein. To identify the structural localization of the bait region, homology modeling and single-particle analysis were applied, resulting in a molecular model of membrane-associated CD109, which allows for the localization of the newly identified cleavage sites for meprin β and the previously published cleavage sites for the metalloproteinase bone morphogenetic protein-1 (BMP-1). Full-length CD109 localized on extracellular vesicles (EVs) was also identified as a release mechanism, and we can show that proteolytic cleavage of CD109 at the cell surface reduces the amount of CD109 sorted to EVs. In summary, we identified meprin β as the first membrane-bound protease to cleave CD109 within the bait region, provide a first structural model for CD109, and show that cell surface proteolysis correlates negatively with CD109 released on EVs.
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http://dx.doi.org/10.3389/fcell.2021.622390DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7960916PMC
March 2021

Discovery and Optimization of Selective Inhibitors of Meprin α (Part II).

Pharmaceuticals (Basel) 2021 Feb 27;14(3). Epub 2021 Feb 27.

Department of Molecular Medicine, Scripps Research, Jupiter, FL 33458, USA.

Meprin α is a zinc metalloproteinase (metzincin) that has been implicated in multiple diseases, including fibrosis and cancers. It has proven difficult to find small molecules that are capable of selectively inhibiting meprin a, or its close relative meprin b, over numerous other metzincins which, if inhibited, would elicit unwanted effects. We recently identified possible molecular starting points for meprin a-specific inhibition through an HTS effort (see part I, preceding paper). Here, in part II, we report further efforts to optimize potency and selectivity. We hope that a hydroxamic acid meprin α inhibitor probe will help define the therapeutic potential for small molecule meprin a inhibition and spur further drug discovery efforts in the area of zinc metalloproteinase inhibition.
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http://dx.doi.org/10.3390/ph14030197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7997411PMC
February 2021

Discovery and Optimization of Selective Inhibitors of Meprin α (Part I).

Pharmaceuticals (Basel) 2021 Feb 28;14(3). Epub 2021 Feb 28.

Rumbaugh-Goodwin Institute for Cancer Research, Nova Southeastern University, 3321 College Avenue, CCR r.605, Fort Lauderdale, FL 33314, USA.

Meprin α and β are zinc-dependent proteinases implicated in multiple diseases including cancers, fibrosis, and Alzheimer's. However, until recently, only a few inhibitors of either meprin were reported and no inhibitors are in preclinical development. Moreover, inhibitors of other metzincins developed in previous years are not effective in inhibiting meprins suggesting the need for de novo discovery effort. To address the paucity of tractable meprin inhibitors we developed ultrahigh-throughput assays and conducted parallel screening of >650,000 compounds against each meprin. As a result of this effort, we identified five selective meprin α hits belonging to three different chemotypes (triazole-hydroxyacetamides, sulfonamide-hydroxypropanamides, and phenoxy-hydroxyacetamides). These hits demonstrated a nanomolar to micromolar inhibitory activity against meprin α with low cytotoxicity and >30-fold selectivity against meprin β and other related metzincincs. These selective inhibitors of meprin α provide a good starting point for further optimization.
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http://dx.doi.org/10.3390/ph14030203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8000592PMC
February 2021

Cathepsin S provokes interleukin-6 (IL-6) trans-signaling through cleavage of the IL-6 receptor in vitro.

Sci Rep 2020 12 10;10(1):21612. Epub 2020 Dec 10.

Department of Pathology, Medical Faculty, Otto-Von-Guericke-University Magdeburg, Magdeburg, Germany.

The cytokine interleukin-6 (IL-6) fulfills its pleiotropic functions via different modes of signaling. Regenerative and anti-inflammatory activities are mediated via classic signaling, in which IL-6 binds to the membrane-bound IL-6 receptor (IL-6R). For IL-6 trans-signaling, which accounts for the pro-inflammatory properties of the cytokine, IL-6 activates its target cells via soluble forms of the IL-6R (sIL-6R). We have previously shown that the majority of sIL-6R in human serum originates from proteolytic cleavage and mapped the cleavage site of the IL-6R. The cleavage occurs between Pro-355 and Val-356, which is the same cleavage site that the metalloprotease ADAM17 uses in vitro. However, sIL-6R serum levels are unchanged in hypomorphic ADAM17 mice, making the involvement of ADAM17 questionable. In order to identify other proteases that could be relevant for sIL-6R generation in vivo, we perform a screening approach based on the known cleavage site. We identify several candidate proteases and characterize the cysteine protease cathepsin S (CTSS) in detail. We show that CTSS is able to cleave the IL-6R in vitro and that the released sIL-6R is biologically active and can induce IL-6 trans-signaling. However, CTSS does not use the Pro-355/Val-356 cleavage site, and sIL-6R serum levels are not altered in Ctss mice. In conclusion, we identify a novel protease of the IL-6R that can induce IL-6 trans-signaling, but does not contribute to steady-state sIL-6R serum levels.
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http://dx.doi.org/10.1038/s41598-020-77884-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730449PMC
December 2020

IL-6 Trans-Signaling in the Brain Influences the Metabolic Phenotype of the 3xTg-AD Mouse Model of Alzheimer's Disease.

Cells 2020 07 2;9(7). Epub 2020 Jul 2.

Institute of Neurosciences and Department of Cellular Biology, Physiology and Immunology, Faculty of Biosciences, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.

Alzheimer's disease (AD) is a neurodegenerative disorder that causes the most prevalent dementia in the elderly people. Obesity and insulin resistance, which may cause major health problems , are risk factors for AD, and cytokines such as interleukin-6 (IL-6) have a role in these conditions. IL-6 can signal either through a membrane receptor or by trans-signaling, which can be inhibited by the soluble form of the co-receptor gp130 (sgp130). We have addressed the possibility that blocking IL-6 trans-signaling in the brain could have an effect in the triple transgenic 3xTg-AD mouse model of AD and/or in obesity progression, by crossing 3xTg-AD mice with GFAP-sgp130Fc mice. To serve as control groups, GFAP-sgp130Fc mice were also crossed with C57BL/6JOlaHsd mice. Seventeen-month-old mice were fed a control diet (18% kcal from fat) and a high-fat diet (HFD; 58.4% kcal from fat). In our experimental conditions, the 3xTg-AD model showed a mild amyloid phenotype, which nevertheless altered the control of body weight and related endocrine and metabolic factors, suggestive of a hypermetabolic state. The inhibition of IL-6 trans-signaling modulated some of these traits in both 3xTg-AD and control mice, particularly during HFD, and in a sex-dependent manner. These experiments provide evidence of IL-6 trans-signaling playing a role in the CNS of a mouse model of AD.
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http://dx.doi.org/10.3390/cells9071605DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7407279PMC
July 2020

Joint Reconstituted Signaling of the IL-6 Receptor via Extracellular Vesicles.

Cells 2020 05 24;9(5). Epub 2020 May 24.

Biochemical Institute, Christian-Albrechts-University Kiel, Otto-Hahn Platz 9, 24118 Kiel, Germany.

Interleukin-6 (IL-6) signaling is a crucial regulatory event important for many biological functions, such as inflammation and tissue regeneration. Accordingly, several pathological conditions are associated with dysregulated IL-6 activity, making it an attractive therapeutic target. For instance, blockade of IL-6 or its α-receptor (IL-6R) by monoclonal antibodies has been successfully used to treat rheumatoid arthritis. However, based on different signaling modes, IL-6 function varies between pro- and anti-inflammatory activity, which is critical for therapeutic intervention. So far, three modes of IL-6 signaling have been described, the classic anti-inflammatory signaling, as well as pro-inflammatory trans-signaling, and trans-presentation. The IL-6/IL-6R complex requires an additional β-receptor (gp130), which is expressed on almost all cells of the human body, to induce STAT3 (signal transducer and activator of signal transcription 3) phosphorylation and subsequent transcriptional regulation. In contrast, the IL-6R is expressed on a limited number of cells, including hepatocytes and immune cells. However, the proteolytic release of the IL-6R enables trans-signaling on cells expressing gp130 only. Here, we demonstrate a fourth possibility of IL-6 signaling that we termed (JRS). We show that IL-6R on extracellular vesicles (EVs) can also be transported to and fused with other cells that lack the IL-6R on their surface. Importantly, JRS via EVs induces delayed STAT3 phosphorylation compared to the well-established trans-signaling mode. EVs isolated from human serum were already shown to carry the IL-6R, and thus this new signaling mode should be considered with regard to signal intervention.
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http://dx.doi.org/10.3390/cells9051307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7291149PMC
May 2020

Meprin β cleaves TREM2 and controls its phagocytic activity on macrophages.

FASEB J 2020 05 1;34(5):6675-6687. Epub 2020 Apr 1.

Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany.

The triggering receptor expressed on myeloid cells 2 (TREM2) is a multifunctional surface protein that affects survival, migration, and phagocytic capacity of myeloid cells. Soluble TREM2 levels were found to be increased in early stages of sporadic and familial Alzheimer's disease (AD) probably reflecting a defensive microglial response to some initial brain damage. The disintegrin and metalloproteases (ADAM) 10 and 17 were identified as TREM2 sheddases. We demonstrate that meprin β is a direct TREM2 cleaving enzyme using ADAM10/17 deficient HEK293 cells. LC-MS/MS analysis of recombinant TREM2 incubated with meprin β revealed predominant cleavage between Arg136 and Asp137, distant to the site identified for ADAM10/17. We further demonstrate that the metalloprotease meprin β cleaves TREM2 on macrophages concomitant with decreased levels of soluble TREM2 in the serum of Mep1b mice compared to WT controls. Isolated BMDMs from Mep1b mice showed significantly increased full-length TREM2 levels and enhanced phagocytosis efficiency compared to WT cells. The diminished constitutive shedding of TREM2 on meprin β deficient macrophages could be rescued by ADAM stimulation through LPS treatment. Our data provide evidence that meprin β is a TREM2 sheddase on macrophages and suggest that multiple proteases may be involved in the generation of soluble TREM2.
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http://dx.doi.org/10.1096/fj.201902183RDOI Listing
May 2020

Meprin β: A novel regulator of blood-brain barrier integrity.

J Cereb Blood Flow Metab 2021 01 16;41(1):31-44. Epub 2020 Feb 16.

Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.

The metalloprotease meprin β (Mep1b) is capable of cleaving cell-adhesion molecules in different tissues (e.g. skin, kidney and intestine) and is dysregulated in several diseases associated with barrier breakdown (Alzheimer´s disease, kidney disruption, inflammatory bowel disease). In this study, we demonstrate that Mep1b is a novel regulator of tight junction (TJ) composition and blood-brain barrier (BBB) integrity in brain endothelium. In Mep1b-transfected mouse brain endothelial cells (bEnd.3), we observed a reduction of the TJ protein claudin-5, decreased transendothelial electrical resistance (TEER) and an elevated permeability to paracellular diffusion marker [C]-inulin. Analysis of global Mep1b knock-out (Mep1b) mice showed increased TJ protein expression (claudin-5, occludin, ZO-1) in cerebral microvessels and increased TEER in cultivated primary mouse brain endothelial compared to wild-type (wt) mice. Furthermore, we investigated the IgG levels in cerebrospinal fluid (CSF) and the brain water content as additional permeability markers and detected lower IgG levels and reduced brain water content in Mep1b mice compared to wt mice. Showing opposing features in overexpression and knock-out, we conclude that Mep1b plays a role in regulating brain endothelial TJ-proteins and therefore affecting BBB tightness in vitro and in vivo.
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http://dx.doi.org/10.1177/0271678X20905206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7747169PMC
January 2021

Loss of ADAMTS19 causes progressive non-syndromic heart valve disease.

Nat Genet 2020 01 16;52(1):40-47. Epub 2019 Dec 16.

Cardiovascular Genetics, Department of Pediatrics, Centre Hospitalier Universitaire Sainte-Justine Research Centre, University of Montreal, Montreal, Quebec, Canada.

Valvular heart disease is observed in approximately 2% of the general population. Although the initial observation is often localized (for example, to the aortic or mitral valve), disease manifestations are regularly observed in the other valves and patients frequently require surgery. Despite the high frequency of heart valve disease, only a handful of genes have so far been identified as the monogenic causes of disease. Here we identify two consanguineous families, each with two affected family members presenting with progressive heart valve disease early in life. Whole-exome sequencing revealed homozygous, truncating nonsense alleles in ADAMTS19 in all four affected individuals. Homozygous knockout mice for Adamts19 show aortic valve dysfunction, recapitulating aspects of the human phenotype. Expression analysis using a lacZ reporter and single-cell RNA sequencing highlight Adamts19 as a novel marker for valvular interstitial cells; inference of gene regulatory networks in valvular interstitial cells positions Adamts19 in a highly discriminatory network driven by the transcription factor lymphoid enhancer-binding factor 1 downstream of the Wnt signaling pathway. Upregulation of endocardial Krüppel-like factor 2 in Adamts19 knockout mice precedes hemodynamic perturbation, showing that a tight balance in the Wnt-Adamts19-Klf2 axis is required for proper valve maturation and maintenance.
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http://dx.doi.org/10.1038/s41588-019-0536-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7197892PMC
January 2020

Role of meprin metalloproteases in metastasis and tumor microenvironment.

Cancer Metastasis Rev 2019 09;38(3):347-356

Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany.

A crucial step for tumor cell extravasation and metastasis is the migration through the extracellular matrix, which requires proteolytic activity. Hence, proteases, particularly matrix metalloproteases (MMPs), have been discussed as therapeutic targets and their inhibition should diminish tumor growth and metastasis. The metalloproteases meprin α and meprin β are highly abundant on intestinal enterocytes and their expression was associated with different stages of colorectal cancer. Due to their ability to cleave extracellular matrix (ECM) components, they were suggested as pro-tumorigenic enzymes. Additionally, both meprins were shown to have pro-inflammatory activity by cleaving cytokines and their receptors, which correlates with chronic intestinal inflammation and associated conditions. On the other hand, meprin β was identified as an essential enzyme for the detachment and renewal of the intestinal mucus, important to prevent bacterial overgrowth and infection. Considering this, it is hard to estimate whether high activity of meprins is generally detrimental or if these enzymes have also protective functions in certain cancer types. For instance, for colorectal cancer, patients with high meprin β expression in tumor tissue exhibit a better survival prognosis, which is completely different to prostate cancer. This demonstrates that the very same enzyme may have contrary effects on tumor initiation and growth, depending on its tissue and subcellular localization. Hence, precise knowledge about proteolytic enzymes is required to design the most efficient therapeutic options for cancer treatment. In this review, we summarize the current findings on meprins' functions, expression, and cancer-associated variants with possible implications for tumor progression and metastasis.
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http://dx.doi.org/10.1007/s10555-019-09805-5DOI Listing
September 2019

IL-6 trans-signaling in the brain influences the behavioral and physio-pathological phenotype of the Tg2576 and 3xTgAD mouse models of Alzheimer's disease.

Brain Behav Immun 2019 11 8;82:145-159. Epub 2019 Aug 8.

Institute of Neurosciences and Department of Cellular Biology, Physiology and Immunology, Faculty of Biosciences, Universitat Autònoma de Barcelona, 08193, Spain. Electronic address:

Alzheimer's disease (AD) is the most commonly diagnosed dementia but its underlying pathological mechanisms still unclear. Neuroinflammation and secretion of cytokines such as interleukin-6 (IL-6) accompany the main hallmarks of the disease: amyloid plaques and neurofibrillary tangles. In this study, we analyzed the role of IL-6 trans-signaling in two mouse models of AD, Tg2576 and 3xTg-AD mice. The inhibition of IL-6 trans-signaling partially rescued the AD-induced mortality in females of both models. Before amyloid plaques deposition, it reversed AD-induced changes in exploration and anxiety (but did not affect locomotion) in Tg2576 female mice. However, after plaque deposition the only behavioral trait affected by the inhibition of IL-6 trans-signaling was locomotion. Results in the Morris water maze suggest that cognitive flexibility was reduced by the blocking of the IL-6 trans-signaling in young and old Tg2576 female mice. The inhibition of IL-6 trans-signaling also decreased amyloid plaque burden in cortex and hippocampus, and Aβ and Aβ levels in the cortex, of Tg2576 female mice. The aforementioned changes might be correlated with changes in blood vessels and matrix structure and organization rather than changes in neuroinflammation. 3xTgAD mice showed a very mild phenotype regarding amyloid cascade, but results were in accordance with those of Tg2576 mice. These results strongly suggest that the inhibition of the IL-6 trans-signaling could represent a powerful therapeutic target in AD.
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http://dx.doi.org/10.1016/j.bbi.2019.08.005DOI Listing
November 2019

Meprin β induces activities of A disintegrin and metalloproteinases 9, 10, and 17 by specific prodomain cleavage.

FASEB J 2019 11 9;33(11):11925-11940. Epub 2019 Aug 9.

Institute of Biochemistry, University of Kiel, Kiel, Germany.

Meprin β is a membrane-bound metalloprotease involved in extracellular matrix assembly and inflammatory processes in health and disease. A disintegrin and metalloproteinase (ADAM)10 and ADAM17 are physiologic relevant sheddases of inactive promeprin β, which influences its substrate repertoire and subsequent biologic functions. Proteomic analysis also revealed several ADAMs as putative meprin β substrates. Here, we demonstrate specific N-terminal processing of ADAM9, 10, and 17 by meprin β and identify cleavage sites within their prodomains. Because ADAM prodomains can act as specific inhibitors, we postulate a role for meprin β in the regulation of ADAM activities. Indeed, prodomain cleavage by meprin β caused increased ADAM protease activities, as observed by peptide-based cleavage assays and demonstrated by increased ectodomain shedding activity. Direct interaction of meprin β and ADAM proteases could be shown by immunofluorescence microscopy and immunoprecipitation experiments. As demonstrated by a bacterial activator of meprin β and additional measurement of TNF-α shedding on bone marrow-derived macrophages, meprin β/ADAM protease interactions likely influence inflammatory conditions. Thus, we identified a novel proteolytic pathway of meprin β with ADAM proteases to control protease activities at the cell surface as part of the protease web.-Wichert, R., Scharfenberg, F., Colmorgen, C., Koudelka, T., Schwarz, J., Wetzel, S., Potempa, B., Potempa, J., Bartsch, J. W., Sagi, I., Tholey, A., Saftig, P., Rose-John, S., Becker-Pauly, C. Meprin β induces activities of A disintegrin and metalloproteinases 9, 10, and 17 by specific prodomain cleavage.
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http://dx.doi.org/10.1096/fj.201801371RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6902663PMC
November 2019

Differences in Shedding of the Interleukin-11 Receptor by the Proteases ADAM9, ADAM10, ADAM17, Meprin α, Meprin β and MT1-MMP.

Int J Mol Sci 2019 Jul 26;20(15). Epub 2019 Jul 26.

Institute of Biochemistry, University of Kiel, Otto-Hahn-Platz 9, 24118 Kiel, Germany.

Interleukin-11 (IL-11) has been associated with inflammatory conditions, bone homeostasis, hematopoiesis, and fertility. So far, these functions have been linked to classical IL-11 signaling via the membrane bound receptor (IL-11R). However, a signaling cascade via the soluble IL-11R (sIL-11R), generated by proteolytic cleavage, can also be induced. This process is called IL-11 trans-signaling. A disintegrin and metalloprotease 10 (ADAM10) and neutrophil elastase were described as ectodomain sheddases of the IL-11R, thereby inducing trans-signaling. Furthermore, previous studies employing approaches for the stimulation and inhibition of endogenous ADAM-proteases indicated that ADAM10, but not ADAM17, can cleave the IL-11R. Herein, we show that several metalloproteases, namely ADAM9, ADAM10, ADAM17, meprin β, and membrane-type 1 matrix metalloprotease/matrix metalloprotease-14 (MT1-MMP/MMP-14) when overexpressed are able to shed the IL-11R. All sIL-11R ectodomains were biologically active and capable of inducing signal transducer and activator of transcription 3 (STAT3) phosphorylation in target cells. The difference observed for ADAM10/17 specificity compared to previous studies can be explained by the different approaches used, such as stimulation of protease activity or making use of cells with genetically deleted enzymes.
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http://dx.doi.org/10.3390/ijms20153677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6696353PMC
July 2019

Degradome of soluble ADAM10 and ADAM17 metalloproteases.

Cell Mol Life Sci 2020 Jan 17;77(2):331-350. Epub 2019 Jun 17.

Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany.

Disintegrin and metalloproteinases (ADAMs) 10 and 17 can release the extracellular part of a variety of membrane-bound proteins via ectodomain shedding important for many biological functions. So far, substrate identification focused exclusively on membrane-anchored ADAM10 and ADAM17. However, besides known shedding of ADAM10, we identified ADAM8 as a protease capable of releasing the ADAM17 ectodomain. Therefore, we investigated whether the soluble ectodomains of ADAM10/17 (sADAM10/17) exhibit an altered substrate spectrum compared to their membrane-bound counterparts. A mass spectrometry-based N-terminomics approach identified 134 protein cleavage events in total and 45 common substrates for sADAM10/17 within the secretome of murine cardiomyocytes. Analysis of these cleavage sites confirmed previously identified amino acid preferences. Further in vitro studies verified fibronectin, cystatin C, sN-cadherin, PCPE-1 as well as sAPP as direct substrates of sADAM10 and/or sADAM17. Overall, we present the first degradome study for sADAM10/17, thereby introducing a new mode of proteolytic activity within the protease web.
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http://dx.doi.org/10.1007/s00018-019-03184-4DOI Listing
January 2020

Regulation of the alternative β-secretase meprin β by ADAM-mediated shedding.

Cell Mol Life Sci 2019 Aug 14;76(16):3193-3206. Epub 2019 Jun 14.

Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany.

Alzheimer's Disease (AD) is the sixth-leading cause of death in industrialized countries. Neurotoxic amyloid-β (Aβ) plaques are one of the pathological hallmarks in AD patient brains. Aβ accumulates in the brain upon sequential, proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretases. However, so far disease-modifying drugs targeting β- and γ-secretase pathways seeking a decrease in the production of toxic Aβ peptides have failed in clinics. It has been demonstrated that the metalloproteinase meprin β acts as an alternative β-secretase, capable of generating truncated Aβ peptides that have been described to be increased in AD patients. This indicates an important β-site cleaving enzyme 1 (BACE-1)-independent contribution of the metalloprotease meprin β within the amyloidogenic pathway and may lead to novel drug targeting avenues. However, meprin β itself is embedded in a complex regulatory network. Remarkably, the anti-amyloidogenic α-secretase a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) is a direct competitor for APP at the cell surface, but also a sheddase of inactive pro-meprin β. Overall, we highlight the current cellular, molecular and structural understanding of meprin β as alternative β-secretase within the complex protease web, regulating APP processing in health and disease.
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http://dx.doi.org/10.1007/s00018-019-03179-1DOI Listing
August 2019

The cancer-associated meprin β variant G32R provides an additional activation site and promotes cancer cell invasion.

J Cell Sci 2019 05 31;132(11). Epub 2019 May 31.

Anatomical Institute, Otto-Hahn Platz 8, 24118 Kiel, Germany

The extracellular metalloprotease meprin β is expressed as a homodimer and is primarily membrane bound. Meprin β can be released from the cell surface by its known sheddases ADAM10 and ADAM17. Activation of pro-meprin β at the cell surface prevents its shedding, thereby stabilizing its proteolytic activity at the plasma membrane. We show that a single amino acid exchange variant (G32R) of meprin β, identified in endometrium cancer, is more active against a peptide substrate and the IL-6 receptor than wild-type meprin β. We demonstrate that the change to an arginine residue at position 32 represents an additional activation site used by furin-like proteases in the Golgi, which consequently leads to reduced shedding by ADAM17. We investigated this meprin β G32R variant to assess cell proliferation, invasion through a collagen IV matrix and outgrowth from tumor spheroids. We found that increased meprin β G32R activity at the cell surface reduces cell proliferation, but increases cell invasion.
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http://dx.doi.org/10.1242/jcs.220665DOI Listing
May 2019

Tethering soluble meprin α in an enzyme complex to the cell surface affects IBD-associated genes.

FASEB J 2019 06 27;33(6):7490-7504. Epub 2019 Mar 27.

Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany.

Biologic activity of proteases is mainly characterized by the substrate specificity, tissue distribution, and cellular localization. The human metalloproteases meprin α and meprin β share 41% sequence identity and exhibit a similar cleavage specificity with a preference for negatively charged amino acids. However, shedding of meprin α by furin on the secretory pathway makes it a secreted enzyme in comparison with the membrane-bound meprin β. In this study, we identified human meprin α and meprin β as forming covalently linked membrane-tethered heterodimers in the early endoplasmic reticulum, thereby preventing furin-mediated secretion of meprin α. Within this newly formed enzyme complex, meprin α was able to be activated on the cell surface and detected by cleavage of a novel specific fluorogenic peptide substrate. However, the known meprin β substrates amyloid precursor protein and CD99 were not shed by membrane-tethered meprin α. On the other hand, being linked to meprin α, activation of or substrate cleavage by meprin β on the cell surface was not altered. Interestingly, proteolytic activity of both proteases was increased in the heteromeric complex, indicating an increased proteolytic potential at the plasma membrane. Because meprins are susceptibility genes for inflammatory bowel disease (IBD), and to investigate the physiologic impact of the enzyme complex, we performed transcriptome analyses of intestinal mucosa from meprin-knockout mice. Comparison of the transcriptional gene analysis data with gene analyses of IBD patients revealed that different gene subsets were dysregulated if meprin α was expressed alone or in the enzyme complex, demonstrating the physiologic and pathophysiological relevance of the meprin heterodimer formation.-Peters, F., Scharfenberg, F., Colmorgen, C., Armbrust, F., Wichert, R., Arnold, P., Potempa, B., Potempa, J., Pietrzik, C. U., Häsler, R., Rosenstiel, P., Becker-Pauly, C. Tethering soluble meprin α in an enzyme complex to the cell surface affects IBD-associated genes.
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http://dx.doi.org/10.1096/fj.201802391RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6529335PMC
June 2019

Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases.

Sci Rep 2019 01 24;9(1):546. Epub 2019 Jan 24.

Institute of Molecular Physiology, Cell and Matrix Biology, Johannes Gutenberg University Mainz, 55099, Mainz, Germany.

Vertebrate fetuins are multi-domain plasma-proteins of the cystatin-superfamily. Human fetuin-A is also known as AHSG, α-Heremans-Schmid-glycoprotein. Gene-knockout in mice identified fetuin-A as essential for calcified-matrix-metabolism and bone-mineralization. Fetuin-B deficient mice, on the other hand, are female infertile due to zona pellucida 'hardening' caused by the metalloproteinase ovastacin in unfertilized oocytes. In wildtype mice fetuin-B inhibits the activity of ovastacin thus maintaining oocytes fertilizable. Here we asked, if fetuins affect further proteases as might be expected from their evolutionary relation to single-domain-cystatins, known as proteinase-inhibitors. We show that fetuin-A is not an inhibitor of any tested protease. In stark contrast, the closely related fetuin-B selectively inhibits astacin-metalloproteinases such as meprins and ovastacin, but not astacins of the tolloid-subfamily, nor any other proteinase. The analysis of fetuin-B expressed in various mammalian cell types, insect cells, and truncated fish-fetuin expressed in bacteria, showed that the cystatin-like domains alone are necessary and sufficient for inhibition. This report highlights fetuin-B as a specific antagonist of ovastacin and meprin-metalloproteinases. Control of ovastacin was shown to be indispensable for female fertility. Meprin inhibition, on the other hand, renders fetuin-B a potential key-player in proteolytic networks controlling angiogenesis, immune-defense, extracellular-matrix-assembly and general cell-signaling, with implications for inflammation, fibrosis, neurodegenerative disorders and cancer.
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http://dx.doi.org/10.1038/s41598-018-37024-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6346019PMC
January 2019

Inhibitors of BMP-1/tolloid-like proteinases: efficacy, selectivity and cellular toxicity.

FEBS Open Bio 2018 Dec 12;8(12):2011-2021. Epub 2018 Nov 12.

Tissue Biology and Therapeutic Engineering Unit (LBTI) UMR5305, CNRS Univ Lyon Université Claude Bernard Lyon1 France.

BMP-1/tolloid-like proteinases belong to the astacin family of human metalloproteinases, together with meprins and ovastacin. They represent promising targets to treat or prevent a wide range of diseases such as fibrotic disorders or cancer. However, the study of their pathophysiological roles is still impaired by the lack of well-characterized inhibitors and the questions that remain regarding their selectivity and efficiency. As a first step towards the identification of suitable tools to be used in functional studies, we have undertaken a systematic comparison of seven molecules known to affect the proteolytic activity of human astacins including three hydroxamates (FG-2575, UK383,367, S33A), the protein sizzled, a new phosphinic inhibitor (RXP-1001) and broad-spectrum protease inhibitors (GM6001, actinonin). Their efficacy , their cellular toxicity and efficacy in cell cultures were thoroughly characterized. We found that these molecules display very different potency and selectivity profiles, with hydroxamate FG-2575 and the protein sizzled being very powerful and selective inhibitors of BMP-1, whereas phosphinic peptide RXP-1001 behaves as a broad-spectrum inhibitor of astacins. Their use should therefore be carefully considered in agreement with the aim of the study to avoid result misinterpretation.
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http://dx.doi.org/10.1002/2211-5463.12540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6275283PMC
December 2018

The metalloprotease ADAMTS4 generates N-truncated Aβ4-x species and marks oligodendrocytes as a source of amyloidogenic peptides in Alzheimer's disease.

Acta Neuropathol 2019 02 13;137(2):239-257. Epub 2018 Nov 13.

Department of Neuropathology, Heinrich-Heine University, Moorenstrasse 5, 40225, Düsseldorf, Germany.

Brain accumulation and aggregation of amyloid-β (Aβ) peptides is a critical step in the pathogenesis of Alzheimer's disease (AD). Full-length Aβ peptides (mainly Aβ1-40 and Aβ1-42) are produced through sequential proteolytic cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. However, studies of autopsy brain samples from AD patients have demonstrated that a large fraction of insoluble Aβ peptides are truncated at the N-terminus, with Aβ4-x peptides being particularly abundant. Aβ4-x peptides are highly aggregation prone, but their origin and any proteases involved in their generation are unknown. We have identified a recognition site for the secreted metalloprotease ADAMTS4 (a disintegrin and metalloproteinase with thrombospondin motifs 4) in the Aβ peptide sequence, which facilitates Aβ4-x peptide generation. Inducible overexpression of ADAMTS4 in HEK293 cells resulted in the secretion of Aβ4-40 but unchanged levels of Aβ1-x peptides. In the 5xFAD mouse model of amyloidosis, Aβ4-x peptides were present not only in amyloid plaque cores and vessel walls, but also in white matter structures co-localized with axonal APP. In the ADAMTS4 knockout background, Aβ4-40 levels were reduced confirming a pivotal role of ADAMTS4 in vivo. Surprisingly, in the adult murine brain, ADAMTS4 was exclusively expressed in oligodendrocytes. Cultured oligodendrocytes secreted a variety of Aβ species, but Aβ4-40 peptides were absent in cultures derived from ADAMTS4 mice indicating that the enzyme was essential for Aβ4-x production in this cell type. These findings establish an enzymatic mechanism for the generation of Aβ4-x peptides. They further identify oligodendrocytes as a source of these highly amyloidogenic Aβ peptides.
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http://dx.doi.org/10.1007/s00401-018-1929-5DOI Listing
February 2019

Propeptide glycosylation and galectin-3 binding decrease proteolytic activation of human proMMP-9/progelatinase B.

FEBS J 2019 03 30;286(5):930-945. Epub 2018 Nov 30.

Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven, Belgium.

Matrix metalloproteinases (MMPs) are secreted as proenzymes, containing propeptides that interact with the catalytic zinc, thereby controlling MMP activation. The MMP-9 propeptide is unique in the MMP family because of its post-translational modification with an N-linked oligosaccharide. ProMMP-9 activation by MMP-3 occurs stepwise by cleavage of the propeptide in an aminoterminal (pro-AT) and carboxyterminal (pro-CT) peptide. We chemically synthesized aglycosyl pro-AT and pro-CT and purified recombinant glycosylated pro-AT . First, we report new cleavage sites in the MMP-9 propeptide by MMP-3 and neutrophil elastase. Additionally, we demonstrated with the use of western blot analysis a higher resistance of glycosylated versus aglycosyl pro-AT against proteolysis by MMP-3, MMP-9, meprin α, neutrophil elastase and by protease-rich synovial fluids from rheumatoid arthritis patients. Moreover, we investigated the effect of glycosylation on proteolytic activation of human proMMP-9 with the use of zymography and dye-quenched gelatin cleavage analysis. Compared to recombinant Sf-9 proMMP-9 glycoforms, larger oligosaccharides of human neutrophil proMMP-9 increased resistance against proteolytic activation. Additionally, proMMP-9 from Congenital Disorder of Glycosylation patients, compared to healthy controls, showed a higher activation rate by MMP-3. Finally, we demonstrated that glycan-galectin-3 interactions reduced proMMP-9 activation. In conclusion, modification of MMP-9 propeptide glycosylation is a fine-tuning mechanism and co-determines the specific activity of MMP-9 in physiology and pathology. ENZYMES: MMP-9 EC 3.4.24.35, MMP-3 EC 3.4.24.17, meprin α EC 3.4.24.18, neutrophil elastase EC 3.4.21.37, trypsin EC 3.4.21.4 and PNGase F EC 3.5.1.52.
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http://dx.doi.org/10.1111/febs.14698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379967PMC
March 2019

Docking of Meprin α to Heparan Sulphate Protects the Endothelium from Inflammatory Cell Extravasation.

Thromb Haemost 2018 Oct 20;118(10):1790-1802. Epub 2018 Sep 20.

Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.

Pulmonary arterial hypertension (PAH) is a rare disease characterized by increased pulmonary pressure and vascular remodelling as a consequence of smooth muscle cell proliferation, endothelial cell dysfunction and inflammatory infiltrates. Meprin α is a metalloproteinase whose substrates include adhesion and cell-cell contact molecules involved in the process of immune cell extravasation. In this study, we aimed to unravel the role of meprin α in PAH-induced vascular remodelling. Our results showed that meprin α was present in the apical membrane of endothelial cells in the lungs and pulmonary arteries of donors and idiopathic PAH (IPAH) patients. Elevated circulating meprin α levels were detected in the plasma of IPAH patients. In vitro binding assays and electron microscopy confirmed binding of meprin α to the glycocalyx of human pulmonary artery endothelial cells (hPAECs). Enzymatic and genetic approaches identified heparan sulphate (HS) as an important determinant of the meprin α binding capacity to hPAEC. Meprin α treatment protected from excessive neutrophil infiltration and the protective effect observed in the presence of neutrophils was partially reversed by removal of HS from hPAEC. Importantly, HS levels in pulmonary arteries were decreased in IPAH patients and binding of meprin α to HS was impaired in IPAH hPAEC. In summary, our results suggest a role of HS in docking meprin α to the endothelium and thus in the modulation of inflammatory cell extravasation. In IPAH, the decreased endothelial HS results in the reduction of meprin α binding which might contribute to enhanced inflammatory cell extravasation and potentially to pathological vascular remodelling.
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http://dx.doi.org/10.1055/s-0038-1670657DOI Listing
October 2018

ADAM17 is required for EGF-R-induced intestinal tumors via IL-6 trans-signaling.

J Exp Med 2018 04 22;215(4):1205-1225. Epub 2018 Feb 22.

Institute of Clinical Molecular Biology, Christian Albrechts Universität Kiel, Kiel, Germany.

Colorectal cancer is treated with antibodies blocking epidermal growth factor receptor (EGF-R), but therapeutic success is limited. EGF-R is stimulated by soluble ligands, which are derived from transmembrane precursors by ADAM17-mediated proteolytic cleavage. In mouse intestinal cancer models in the absence of ADAM17, tumorigenesis was almost completely inhibited, and the few remaining tumors were of low-grade dysplasia. RNA sequencing analysis demonstrated down-regulation of STAT3 and Wnt pathway components. Because EGF-R on myeloid cells, but not on intestinal epithelial cells, is required for intestinal cancer and because IL-6 is induced via EGF-R stimulation, we analyzed the role of IL-6 signaling. Tumor formation was equally impaired in IL-6 mice and sgp130Fc transgenic mice, in which only trans-signaling via soluble IL-6R is abrogated. ADAM17 is needed for EGF-R-mediated induction of IL-6 synthesis, which via IL-6 trans-signaling induces β-catenin-dependent tumorigenesis. Our data reveal the possibility of a novel strategy for treatment of colorectal cancer that could circumvent intrinsic and acquired resistance to EGF-R blockade.
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http://dx.doi.org/10.1084/jem.20171696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5881468PMC
April 2018

Mucus Detachment by Host Metalloprotease Meprin β Requires Shedding of Its Inactive Pro-form, which Is Abrogated by the Pathogenic Protease RgpB.

Cell Rep 2017 Nov;21(8):2090-2103

Institute of Biochemistry, University of Kiel, Kiel, Germany. Electronic address:

The host metalloprotease meprin β is required for mucin 2 (MUC2) cleavage, which drives intestinal mucus detachment and prevents bacterial overgrowth. To gain access to the cleavage site in MUC2, meprin β must be proteolytically shed from epithelial cells. Hence, regulation of meprin β shedding and activation is important for physiological and pathophysiological conditions. Here, we demonstrate that meprin β activation and shedding are mutually exclusive events. Employing ex vivo small intestinal organoid and cell culture experiments, we found that ADAM-mediated shedding is restricted to the inactive pro-form of meprin β and is completely inhibited upon its conversion to the active form at the cell surface. This strict regulation of meprin β activity can be overridden by pathogens, as demonstrated for the bacterial protease Arg-gingipain (RgpB). This secreted cysteine protease potently converts membrane-bound meprin β into its active form, impairing meprin β shedding and its function as a mucus-detaching protease.
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http://dx.doi.org/10.1016/j.celrep.2017.10.087DOI Listing
November 2017

Cancer-associated mutations in the canonical cleavage site do not influence CD99 shedding by the metalloprotease meprin β but alter cell migration .

Oncotarget 2017 Aug 4;8(33):54873-54888. Epub 2017 Jul 4.

Unit for Degradomics of the Protease Web, Institute of Biochemistry, University of Kiel, 24118 Kiel, Germany.

Transendothelial cell migration (TEM) is crucial for inflammation and metastasis. The adhesion molecule CD99 was shown to be important for correct immune cell extravasation and is highly expressed on certain cancer cells. Recently, we demonstrated that ectodomain shedding of CD99 by the metalloprotease meprin β promotes TEM . In this study, we employed an acute inflammation model (air pouch/carrageenan) and found significantly less infiltrated cells in meprin β knock-out animals validating the previously observed pro-inflammatory activity. To further analyze the impact of meprin β on CD99 shedding with regard to cell adhesion and proliferation we characterized two lung cancer associated CD99 variants (D92H, D92Y), carrying point mutations at the main cleavage site. Interestingly, ectodomain shedding of these variants by meprin β was still detectable. However the cleavage site shifted to adjacent positions. Nevertheless, expression of CD99 variants D92H and D92Y revealed partial misfolding and proteasomal degradation. A previously observed influence of CD99 on Src activation and increased proliferation could not be confirmed in this study, independent of wild-type CD99 or the variants D92H and D92Y. However, we identified meprin β as a potent inducer of Src phosphorylation. Importantly, we found significantly increased cell migration when expressing the cancer-associated CD99 variant D92H compared to the wild-type protein.
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http://dx.doi.org/10.18632/oncotarget.18966DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5589627PMC
August 2017

Meprin metalloproteases: Molecular regulation and function in inflammation and fibrosis.

Biochim Biophys Acta Mol Cell Res 2017 Nov 11;1864(11 Pt B):2096-2104. Epub 2017 May 11.

Unit for Degradomics of the Protease Web, Institute of Biochemistry, University of Kiel, Germany. Electronic address:

The zinc-endopeptidases meprin α and meprin β are extracellular proteases involved in connective tissue homeostasis, intestinal barrier function and immunological processes. Meprins are unique among other extracellular proteases with regard to cleavage specificity and structure. Meprin α and meprin β have a strong preference for negatively charged amino acids around the scissile bond, reflected by cleavage sites identified in procollagen I, the amyloid precursor protein (APP) and the interleukin-6 receptor (IL-6R). In this review we report on recent findings that summarize the complex molecular regulation of meprins, particular folding, activation and shedding. Dysregulation of meprin α and meprin β is often associated with pathological conditions such as neurodegeneration, inflammatory bowel disease and fibrosis. Based on mouse models and patient data we suggest meprins as possible key regulators in the onset and progression of fibrotic disorders, leading to severe diseases such as pulmonary hypertension. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.
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http://dx.doi.org/10.1016/j.bbamcr.2017.05.011DOI Listing
November 2017

Discovery of an enzyme and substrate selective inhibitor of ADAM10 using an exosite-binding glycosylated substrate.

Sci Rep 2016 Dec 5;6(1):11. Epub 2016 Dec 5.

Department of Drug Discovery and Development, Harrison School of Pharmacy, 3211B Walker Building, Auburn University, Auburn, Alabama, 36849, USA.

ADAM10 and ADAM17 have been shown to contribute to the acquired drug resistance of HER2-positive breast cancer in response to trastuzumab. The majority of ADAM10 and ADAM17 inhibitor development has been focused on the discovery of compounds that bind the active site zinc, however, in recent years, there has been a shift from active site to secondary substrate binding site (exosite) inhibitor discovery in order to identify non-zinc-binding molecules. In the present work a glycosylated, exosite-binding substrate of ADAM10 and ADAM17 was utilized to screen 370,276 compounds from the MLPCN collection. As a result of this uHTS effort, a selective, time-dependent, non-zinc-binding inhibitor of ADAM10 with K = 883 nM was discovered. This compound exhibited low cell toxicity and was able to selectively inhibit shedding of known ADAM10 substrates in several cell-based models. We hypothesize that differential glycosylation of these cognate substrates is the source of selectivity of our novel inhibitor. The data indicate that this novel inhibitor can be used as an in vitro and, potentially, in vivo, probe of ADAM10 activity. Additionally, results of the present and prior studies strongly suggest that glycosylated substrate are applicable as screening agents for discovery of selective ADAM probes and therapeutics.
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http://dx.doi.org/10.1038/s41598-016-0013-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5431342PMC
December 2016

Meprin β and BMP-1 are differentially regulated by CaCl.

Cell Calcium 2017 07 19;65:8-13. Epub 2017 Mar 19.

Anatomical Institute, Otto-Hahn-Platz 8, 24118 Kiel, Germany. Electronic address:

The two metalloproteases meprin β and bone morphogenetic protein 1 (BMP-1) are both members of the astacin protease family. They share specificity for negatively charged residues around the scissile bond and they are expressed in overlapping compartments of the human body. One important proteolytic substrate they share is pro-collagen I. Ablation of one of the two proteases however leads to different collagen I associated phenotypes in vivo. Over the last years calcium emerged as a regulator for the proteolytic activity of both enzymes. For meprin β a reduction and for BMP-1 an increase in activity was reported under increasing calcium concentrations. Here we revisit different compartments that rely on pro-collagen I maturation and explore the crystal structure of both proteases to highlight possible calcium binding sites. With this we aim to emphasize a to date underestimated regulator that influences both proteases.
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http://dx.doi.org/10.1016/j.ceca.2017.03.005DOI Listing
July 2017

Meprin Metalloproteases Generate Biologically Active Soluble Interleukin-6 Receptor to Induce Trans-Signaling.

Sci Rep 2017 03 9;7:44053. Epub 2017 Mar 9.

Institute of Biochemistry, University of Kiel, 24118 Kiel, Germany.

Soluble Interleukin-6 receptor (sIL-6R) mediated trans-signaling is an important pro-inflammatory stimulus associated with pathological conditions, such as arthritis, neurodegeneration and inflammatory bowel disease. The sIL-6R is generated proteolytically from its membrane bound form and A Disintegrin And Metalloprotease (ADAM) 10 and 17 were shown to perform ectodomain shedding of the receptor in vitro and in vivo. However, under certain conditions not all sIL-6R could be assigned to ADAM10/17 activity. Here, we demonstrate that the IL-6R is a shedding substrate of soluble meprin α and membrane bound meprin β, resulting in bioactive sIL-6R that is capable of inducing IL-6 trans-signaling. We determined cleavage within the N-terminal part of the IL-6R stalk region, distinct from the cleavage site reported for ADAM10/17. Interestingly, meprin β can be shed from the cell surface by ADAM10/17 and the observation that soluble meprin β is not capable of shedding the IL-6R suggests a regulatory mechanism towards trans-signaling. Additionally, we observed a significant negative correlation of meprin β expression and IL-6R levels on human granulocytes, providing evidence for in vivo function of this proteolytic interaction.
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http://dx.doi.org/10.1038/srep44053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5343444PMC
March 2017
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