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Armbrust F, Bickenbach K, Altmeppen H, Foggetti A, Winkelmann A, Wulff P, Glatzel M, Pietrzik CU, Becker-Pauly C. A novel mouse model for N-terminal truncated Aβ2-x generation through meprin β overexpression in astrocytes. Cell Mol Life Sci 2024; 81:139. [PMID: 38480559 PMCID: PMC10937767 DOI: 10.1007/s00018-024-05139-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 01/15/2024] [Accepted: 01/18/2024] [Indexed: 03/17/2024]
Abstract
Neurotoxic amyloid-β (Aβ) peptides cause neurodegeneration in Alzheimer's disease (AD) patients' brains. They are released upon proteolytic processing of the amyloid precursor protein (APP) extracellularly at the β-secretase site and intramembranously at the γ-secretase site. Several AD mouse models were developed to conduct respective research in vivo. Most of these classical models overexpress human APP with mutations driving AD-associated pathogenic APP processing. However, the resulting pattern of Aβ species in the mouse brains differs from those observed in AD patients' brains. Particularly mutations proximal to the β-secretase cleavage site (e.g., the so-called Swedish APP (APPswe) fostering Aβ1-x formation) lead to artificial Aβ production, as N-terminally truncated Aβ peptides are hardly present in these mouse brains. Meprin β is an alternative β-secretase upregulated in brains of AD patients and capable of generating N-terminally truncated Aβ2-x peptides. Therefore, we aimed to generate a mouse model for the production of so far underestimated Aβ2-x peptides by conditionally overexpressing meprin β in astrocytes. We chose astrocytes as meprin β was detected in this cell type in close proximity to Aβ plaques in AD patients' brains. The meprin β-overexpressing mice showed elevated amyloidogenic APP processing detected with a newly generated neo-epitope-specific antibody. Furthermore, we observed elevated Aβ production from endogenous APP as well as AD-related behavior changes (hyperlocomotion and deficits in spatial memory). The novel mouse model as well as the established tools and methods will be helpful to further characterize APP cleavage and the impact of different Aβ species in future studies.
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Affiliation(s)
- Fred Armbrust
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany.
| | - Kira Bickenbach
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany
| | - Hermann Altmeppen
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Angelica Foggetti
- Institute of Physiology, University of Kiel, Kiel, Germany
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining, 314400, China
- College of Medicine & Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
| | - Anne Winkelmann
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany
| | - Peer Wulff
- Institute of Physiology, University of Kiel, Kiel, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Claus U Pietrzik
- Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Christoph Becker-Pauly
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany.
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Abousaad S, Ahmed F, Abouzeid A, Ongeri EM. Meprin β expression modulates the interleukin-6 mediated JAK2-STAT3 signaling pathway in ischemia/reperfusion-induced kidney injury. Physiol Rep 2022; 10:e15468. [PMID: 36117389 PMCID: PMC9483619 DOI: 10.14814/phy2.15468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023] Open
Abstract
Meprin metalloproteinases have been implicated in the pathophysiology of ischemia/reperfusion (IR)-induced kidney injury. Previous in vitro data showed that meprin β proteolytically processes interleukin-6 (IL-6) resulting in its inactivation. Recently, meprin-β was also shown to cleave the IL-6 receptor. The goal of this study was to determine how meprin β expression impacts IL-6 and downstream modulators of the JAK2-STAT3-mediated signaling pathway in IR-induced kidney injury. IR was induced in 12-week-old male wild-type (WT) and meprin β knockout (βKO) mice and kidneys obtained at 24 h post-IR. Real-time PCR, western blot, and immunostaining/microscopy approaches were used to quantify mRNA and protein levels respectively, and immunofluorescence counterstaining with proximal tubule (PT) markers to determine protein localization. The mRNA levels for IL-6, CASP3 and BCL-2 increased significantly in both genotypes. Interestingly, western blot data showed increases in protein levels for IL-6, CASP3, and BCL-2 in the βKO but not in WT kidneys. However, immunohistochemical data showed increases in IL-6, CASP3, and BCL-2 proteins in select kidney tubules in both genotypes, shown to be PTs by immunofluorescence counterstaining. IR-induced increases in p-STAT-3 and p-JAK-2 in βKO at a global level but immunoflourescence counterstaining demonstrated p-JAK2 and p-STAT3 increases in select PT for both genotypes. BCL-2 increased only in the renal corpuscle of WT kidneys, suggesting a role for meprins expressed in leukocytes. Immunohistochemical analysis confirmed higher levels of leukocyte infiltration in WT kidneys when compared to βKO kidneys. The present data demonstrate that meprin β modulates IR-induced kidney injury in part via IL-6/JAK2/STAT3-mediated signaling.
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Affiliation(s)
- Shaymaa Abousaad
- Department of KinesiologyCollege of Health and Human Sciences, North Carolina A&T State UniversityGreensboroNorth CarolinaUSA
| | - Faihaa Ahmed
- Department of KinesiologyCollege of Health and Human Sciences, North Carolina A&T State UniversityGreensboroNorth CarolinaUSA
| | - Ayman Abouzeid
- Department of KinesiologyCollege of Health and Human Sciences, North Carolina A&T State UniversityGreensboroNorth CarolinaUSA
| | - Elimelda Moige Ongeri
- Department of KinesiologyCollege of Health and Human Sciences, North Carolina A&T State UniversityGreensboroNorth CarolinaUSA
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Gellrich A, Scharfenberg F, Peters F, Sammel M, Helm O, Armbrust F, Schmidt F, Lokau J, Garbers C, Sebens S, Arnold P, Becker-Pauly C. Characterization of the Cancer-Associated Meprin Βeta Variants G45R and G89R. Front Mol Biosci 2021; 8:702341. [PMID: 34692768 PMCID: PMC8526939 DOI: 10.3389/fmolb.2021.702341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/16/2021] [Indexed: 11/23/2022] Open
Abstract
Meprin β is a metalloprotease associated with neurodegeneration, inflammation, extracellular matrix homeostasis, transendothelial cell migration, and cancer. In this study, we investigated two melanoma-associated variants of meprin β, both exhibiting a single amino acid exchange, namely, meprin β G45R and G89R. Based on the structural data of meprin β and with regard to the position of the amino acid exchanges, we hypothesized an increase in proteolytic activity in the case of the G45R variant due to the induction of a potential new activation site and a decrease in proteolytic activity from the G89R variant due to structural instability. Indeed, the G89R variant showed, overall, a reduced expression level compared to wild-type meprin β, accompanied by decreased activity and lower cell surface expression but strong accumulation in the endoplasmic reticulum. This was further supported by the analysis of the shedding of the interleukin-6 receptor (IL-6R) by meprin β and its variants. In transfected HEK cells, the G89R variant was found to generate less soluble IL-6R, whereas the expression of meprin β G45R resulted in increased shedding of the IL-6R compared to wild-type meprin β and the G89R variant. A similar tendency of the induced shedding capacity of G45R was seen for the well-described meprin β substrate CD99. Furthermore, employing an assay for cell migration in a collagen IV matrix, we observed that the transfection of wild-type meprin β and the G45R variant resulted in increased migration of HeLa cells, while the G89R variant led to diminished mobility.
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Affiliation(s)
| | | | - Florian Peters
- Department of Ophthalmology, Laboratory for Retinal Cell Biology, University Hospital Zurich, Zurich, Switzerland
| | - Martin Sammel
- Biochemical Institute, Kiel University, Kiel, Germany
| | - Ole Helm
- Institute for Experimental Cancer Research, Kiel University, Kiel, Germany
| | - Fred Armbrust
- Biochemical Institute, Kiel University, Kiel, Germany
| | | | - Juliane Lokau
- Institute of Pathology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Christoph Garbers
- Institute of Pathology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Susanne Sebens
- Institute for Experimental Cancer Research, Kiel University, Kiel, Germany
| | - Philipp Arnold
- Institute of Functional and Clinical Anatomy, FAU Erlangen, Erlangen, Germany
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Armbrust F, Bickenbach K, Marengo L, Pietrzik C, Becker-Pauly C. The Swedish dilemma - the almost exclusive use of APPswe-based mouse models impedes adequate evaluation of alternative β-secretases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119164. [PMID: 34699873 DOI: 10.1016/j.bbamcr.2021.119164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/30/2021] [Accepted: 10/11/2021] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia, however incurable so far. It is widely accepted that aggregated amyloid β (Aβ) peptides play a crucial role for the pathogenesis of AD, as they cause neurotoxicity and deposit as so-called Aβ plaques in AD patient brains. Aβ peptides derive from the amyloid precursor protein (APP) upon consecutive cleavage at the β- and γ-secretase site. Hence, mutations in the APP gene are often associated with autosomal dominant inherited AD. Almost thirty years ago, two mutations at the β-secretase site were observed in two Swedish families (termed Swedish APP (APPswe) mutations), which led to early-onset AD. Consequently, APPswe was established in almost every common AD mouse model, as it contributes to early Aβ plaque formation and cognitive impairments. Analyzing these APPswe-based mouse models, the aspartyl protease BACE1 has been evolving as the prominent β-secretase responsible for Aβ release in AD and as the most important therapeutic target for AD treatment. However, with respect to β-secretase processing, the very rare occurring APPswe variant substantially differs from wild-type APP. BACE1 dominates APPswe processing resulting in the release of Aβ1-x, whereas N-terminally truncated Aβ forms are scarcely generated. However, these N-terminally truncated Aβ species such as Aβ2-x, Aβ3-x and Aβ4-x are elevated in AD patient brains and exhibit an increased potential to aggregate compared to Aβ1-x peptides. Proteases such as meprin β, cathepsin B and ADAMTS4 were identified as alternative β-secretases being capable of generating these N-terminally truncated Aβ species from wild-type APP. However, neither meprin β nor cathepsin B are capable of generating N-terminally truncated Aβ peptides from APPswe. Hence, the role of BACE1 for the Aβ formation during AD might be overrepresented through the excessive use of APPswe mouse models. In this review we critically discuss the consideration of BACE1 as the most promising therapeutic target. Shifting the focus of AD research towards alternative β secretases might unveil promising alternatives to BACE1 inhibitors constantly failing in clinical trials due to ineffectiveness and harmful side effects.
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Affiliation(s)
- Fred Armbrust
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Kiel, Germany
| | - Kira Bickenbach
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Kiel, Germany
| | - Liana Marengo
- Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Claus Pietrzik
- Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.
| | - Christoph Becker-Pauly
- Biochemical Institute, Unit for Degradomics of the Protease Web, University of Kiel, Kiel, Germany.
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Regulation of meprin metalloproteases in mucosal homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119158. [PMID: 34626680 DOI: 10.1016/j.bbamcr.2021.119158] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/15/2021] [Accepted: 09/20/2021] [Indexed: 12/20/2022]
Abstract
Mucus is covering the entire epithelium of the gastrointestinal tract (GIT), building the interface for the symbiosis between microorganisms and their host. Hence, a disrupted mucosal barrier or alterations of proper mucus composition, including the gut microbiota, can cause severe infection and inflammation. Meprin metalloproteases are well-known to cleave various pro-inflammatory molecules, contributing to the onset and progression of pathological conditions including sepsis, pulmonary hypertension or inflammatory bowel disease (IBD). Moreover, meprins have an impact on migration and infiltration of immune cells like monocytes or leukocytes during intestinal inflammation by cleaving tight junction proteins or cell adhesion molecules, thereby disrupting epithelial cell barrier and promoting transendothelial cell migration. Interestingly, both meprin α and meprin β are susceptibility genes for IBD. However, both genes are significantly downregulated in inflamed intestinal tissue in contrast to healthy donors. Therefore, a detailed understanding of the underlying molecular mechanisms is the basis for developing new and effective therapies against manifold pathologies like IBD. This review focuses on the regulation of meprin metalloproteases and its impact on physiological and pathological conditions related to mucosal homeostasis.
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