IRhom2 Promotes Lupus Nephritis through ADAM17-Dependent TNF-α and EGFR Signaling
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ABSTRACT: Lupus nephritis (LN) often results in progressive renal dysfunction. The inactive Rhomboid 2 (iRhom2) is a newly identified key regulator of A disintegrin and metalloprotease 17 (ADAM17), whose substrates, such as TNF-α and heparin-binding EGF (HB-EGF), have been implicated in the pathogenesis of chronic kidney disease. Here we demonstrate that deficiency of iRhom2 protects the lupus-prone Fcgr2b-/- mice from developing severe kidney damage without altering anti-double stranded (ds) DNA Ab production, by simultaneously blocking the HB-EGF/EGFR and the TNF-α signaling in the kidney tissues. Unbiased transcriptome profiling of kidneys and kidney macrophages revealed that TNF-α and HB-EGF/EGFR signaling pathways are highly upregulated in Fcgr2b-/- mice; alterations that were diminished in the absence of iRhom2. Pharmacological blockade of either TNF-α or EGFR signaling protected Fcgr2b-/- mice from severe renal damage. Finally, kidneys from LN patients showed increased iRhom2 and HB-EGF expression, with interstitial HB-EGF expression significantly associated with chronicity indices. Our data suggest that activation of iRhom2/ADAM17-dependent TNF-α and EGFR signaling plays a crucial role in mediating irreversible kidney damage in LN, thereby uncovering a novel target for selective and simultaneous dual inhibition of two major pathological pathways in the effector arm of the disease.
Project description:Ectodomain shedding, which is the proteolytic release of transmembrane proteins from the cell surface, is crucial for cell-to-cell communication and other biological processes. The metalloproteinase ADAM17 mediates ectodomain shedding of over 50 transmembrane proteins ranging from cytokines and growth factors, such as TNF and EGFR ligands, to signaling receptors and adhesion molecules. Yet, the ADAM17 sheddome is only partly defined and biological functions of the protease have not been fully characterized. Some ADAM17 substrates (e.g. HB-EGF) are known to bind to heparan sulfate proteoglycans (HSPG), and we hypothesised that such substrates would be under-represented in traditional secretome analyses, due to their binding to cell surface or pericellular HSPGs. Thus, to identify novel HSPG-binding ADAM17 substrates, we developed a proteomic workflow that involves addition of heparin to solubilize HSPG-binding proteins from the cell layer, thereby allowing their mass spectrometry detection by heparin-secretome (HEP-SEC) analysis. Applying this methodology to murine embryonic fibroblasts stimulated with an ADAM17 activator enabled us to identify 47 transmembrane proteins that were shed in response to ADAM17 activation. This included known HSPG-binding ADAM17 substrates (i.e. HB-EGF, CX3CL1) and 14 novel HSPG-binding putative ADAM17 substrates.
Project description:The cell surface metalloprotease ADAM17 and its binding partners iRhom2 and iRhom1 modulate cell-cell interactions by mediating the release of membrane proteins such as TNFa and EGFR-ligands from the cell surface. Most cell types express both iRhoms, though myeloid cells exclusively express iRhom2, and iRhom1 is the main iRhom in the mouse brain. Here we report that iRhom2 is uniquely expressed in olfactory sensory neurons (OSNs), highly specialized cells expressing one olfactory receptor (OR) from a repertoire of over a thousand OR genes in mice. iRhom2-/- mice had no evident morphological defects in the olfactory epithelium (OE), yet RNAseq analysis revealed differential expression of a small subset of ORs. Notably, while the majority of ORs remain unaffected in iRhom2-/- OE, OSNs expressing ORs that are enriched in iRhom2-/- OE showed fewer gene expression changes upon odor environmental changes than the majority of OSNs. Moreover, we discovered an inverse correlation between the expression of iRhom2 compared to OSN activity genes and that odor exposure negatively regulates iRhom2 expression. Given that ORs are specialized G-protein coupled receptors (GPCRs) and many GPCRs activate iRhom2/ADAM17, we investigated if ORs could activate iRhom2/ADAM17. Activation of OR2AT4 by its agonist sandalore in keratinocytes, where this receptor is ectopically expressed, leads to ERK1/2 phosphorylation, likely via an iRhom2/ADAM17-dependent pathway. Taken together, these findings point to a mechanism by which odor stimulation of OSNs activates iRhom2/ADAM17 catalytic activity, resulting in downstream transcriptional changes to the OR repertoire and activity genes, and driving a negative feedback loop to downregulate iRhom2 expression.
Project description:Macrophages in the tumor microenvironment have a substantial impact on tumor progression. Depending on the signaling environment in the tumor, macrophages can either support or constrain tumor progression. It is therefore of therapeutic interest to identify the tumor-derived factors that control macrophage education. With this aim, we correlated the expression of A Disintegrin and Metalloproteinase (ADAM) proteases, which are key mediators of cell-cell signaling, to the expression of protumorigenic macrophage markers in human cancer cohorts. We identified ADAM17, a sheddase upregulated in many cancer types, as a protein of interest. Depletion of ADAM17 in cancer cell lines reduced the expression of several protumorigenic markers in neighboring macrophages in vitro as well as in mouse models. Moreover, ADAM17–/– educated macrophages demonstrated a reduced ability to induce cancer cell invasion. Using mass spectrometry–based proteomics and ELISA, we identified HB-EGF and AREG, shed by ADAM17 in the cancer cells, as the implicated molecular mediators of macrophage education. Additionally, RNA-Seq and ELISA experiments revealed that ADAM17-dependent HB-EGF ligand release induced the expression and secretion of CXCL chemokines in macrophages, which in turn stimulated cancer cell invasion. In conclusion, we provide evidence that ADAM17 mediates a paracrine EGFR-ligand-chemokine feedback loop, whereby cancer cells hijack macrophages to promote tumor progression.
Project description:Macrophages in the tumor microenvironment have a significant impact on tumor progression. Depending on the signaling environment in the tumor, macrophages can either support or constrain tumor growth and metastasis. It is therefore of therapeutic interest to identify the tumor-derived factors that control macrophage education. With this aim, we correlated the expression of ADAM proteases, which are key mediators of cell-cell signaling, to the expression of pro-tumorigenic macrophage markers in human cancer cohorts. We identified ADAM17, a sheddase upregulated in many cancer types, as a protein of interest. Depletion of ADAM17 in cancer cell lines reduced the expression of several pro-tumorigenic markers in neighboring macrophages in vitro as well as in mouse tumor models. Accordingly, ADAM17-/- educated macrophages demonstrated a reduced ability to induce cancer cell invasion. Using quantitative mass spectrometry-based proteomics, we identified HB-EGF, shed by ADAM17 in the cancer cells, as the implicated molecular mediator of macrophage education. Additionally, RNA-seq and ELISA experiments revealed that ADAM17-dependent HB-EGF release induces the expression and secretion of CXCL chemokines in macrophages, which in turn stimulates cancer cell invasion. In conclusion, we provide evidence that ADAM17 mediates a paracrine HB-EGF-chemokine feedback loop, whereby cancer cells hijack macrophages to promote tumor progression.
Project description:Membrane-tethered signalling proteins such as TNF������ and many EGF receptor ligands undergo shedding by the metalloproteinase ADAM17 to get released. The pseudoproteases iRhom1 and iRhom2 are important for the ER exit and activity of ADAM17. Yet, their structural requirements to promote ER exit remained unexplored. Utilising in silico and in vitro methods, we here map the conserved iRhom homology domain (IRHD) and provide insights into its structure and function. We identified a highly conserved motif within the IRHD, which is indispensable for the ER exit of iRhoms and termed it CERES (conserved ER exit sequence). Strikingly, single point mutations in CERES abrogate the ER exit without disrupting other iRhom functions. We confirmed the physiological significance of CERES by inactivating it in mice which abrogates ADAM17-mediated shedding ex vivo and in vivo. This demonstrates a crucial role of CERES in the ADAM17-dependent release of various growth factor and cytokine signals.
Project description:We report a pleiotropic disease due to loss-of-function mutations in RHBDF2, the gene encoding iRHOM2, in 2 kindreds with recurrent infections in different organs. One patient had recurrent pneumonia but no colon involvement, another had recurrent infectious hemorrhagic colitis but no lung involvement, and the other two experienced recurrent respiratory infections. Loss of iRHOM2, a rhomboid superfamily member that regulates the ADAM17 metalloproteinase, caused defective ADAM17-dependent cleavage and release of cytokines, including TNF and amphiregulin. To understand the diverse clinical phenotypes, we challenged Rhbdf2-/- mice with Pseudomonas aeruginosa by nasal gavage and observed more severe pneumonia whereas infection with Citrobacter rodentium caused worse inflammatory colitis than wild-type mice. The fecal microbiota in the colitis patient had characteristic oral species that can predispose to colitis. Thus, a new human immunodeficiency arising from iRHOM2 deficiency causes divergent disease phenotypes that can involve the local microbial environment.
Project description:We report a pleiotropic disease due to loss-of-function mutations in RHBDF2, the gene encoding iRHOM2, in 2 kindreds with recurrent infections in different organs. One patient had recurrent pneumonia but no colon involvement, another had recurrent infectious hemorrhagic colitis but no lung involvement, and the other two experienced recurrent respiratory infections. Loss of iRHOM2, a rhomboid superfamily member that regulates the ADAM17 metalloproteinase, caused defective ADAM17-dependent cleavage and release of cytokines, including TNF and amphiregulin. To understand the diverse clinical phenotypes, we challenged Rhbdf2-/- mice with Pseudomonas aeruginosa by nasal gavage and observed more severe pneumonia whereas infection with Citrobacter rodentium caused worse inflammatory colitis than wild-type mice. The fecal microbiota in the colitis patient had characteristic oral species that can predispose to colitis. Thus, a new human immunodeficiency arising from iRHOM2 deficiency causes divergent disease phenotypes that can involve the local microbial environment.
Project description:The cell surface receptor TREM2 is a key genetic risk factor and drug target in Alzheimer’s disease (AD). In the brain, TREM2 is expressed in microglia, where it undergoes proteolytic cleavage, linked to AD risk, but the responsible protease in microglia is unknown. Another microglia-expressed AD risk factor is inactive rhomboid 2 (iRhom2, RHBDF2), which acts as a non-catalytic subunit of the metalloprotease ADAM17. Its function in AD is unknown. To determine whether loss of iRhom2 and ADAM17 leads to a reduction of cleavage of additional membrane proteins beyond TNF, we used the ‘high-performance secretome protein enrichment with click sugars’ (hiSPECS) method for mass spectrometry-based secretome analysis (Tüshaus et al, 2020). hiSPECS uses a metabolic labeling with click sugars, which allows to culture cells in the presence of serum or serum-like supplements. Therefore, we have used the murine microglia cell line BV2 and introduced CRISPR/Cas9-mediated knockouts of RHBDF2/iRhom2 and ADAM17.
Project description:Doxorubicin as a commonly used anthracycline has become the cornerstone of chemotherapy in a wide range of cancers owing to its high efficacy. However, clinical applications of doxorubicin are limited mainly due to its toxic effects on myocardium but the pathogenic mechanism of doxorubicin-induced cardiomyopathy are poorly understood. ADAM17 is known as tumor necrosis factor α converting enzyme (TACE), and the cleavage of TNF-α by ADAM17 is a prerequisite for pro-inflammatory TNF-α activity, which raises a possibility that inhibition of ADAM17 may exert a beneficial effect on disease processes where TNF-α plays an essential role. Our previous research has shown that cardiomyocyte specific knockout of ADAM17 improves diabetic cardiomyopathy by modulating cardiomyocyte apoptosis. However, the relationship between ADAM17 and doxorubicin-induced cardiomyopathy is unclear.Through RNA sequencing analysis, we observed significant changes in the TNF signaling pathway genes in the heart tissue of mice with or without cardiomyocyte ADAM17 knockout.