The mechanosensory channel PIEZO1 functions upstream of angiopoietin/TIE/FOXO1 signaling in lymphatic development.

Lymphedema is a debilitating disease with no effective cure and affects an estimated 250 million individuals worldwide. Prior studies have identified mutations in piezo-type mechanosensitive ion channel component 1 (PIEZO1), angiopoietin 2 (ANGPT2), and tyrosine kinase with Ig-like and EGF-like domains 1 (TIE1) in patients with primary lymphedema. Here, we identified crosstalk between these molecules and showed that activation of the mechanosensory channel PIEZO1 in lymphatic endothelial cells (LECs) caused rapid exocytosis of the TIE ligand ANGPT2, ectodomain shedding of TIE1 by disintegrin and metalloproteinase domain-containing protein 17 (ADAM17), and increased TIE/PI3K/AKT signaling, followed by nuclear export of the transcription factor FOXO1. These data establish a functional network between lymphedema-associated genes and provide what we believe to be the first molecular mechanism bridging channel function with vascular signaling and intracellular events culminating in transcriptional regulation of genes expressed in LECs. Our study provides insights into the regulation of lymphatic function and molecular pathways involved in human disease.

FGF23 as a Potential Pathophysiological Factor in Peripheral Arterial Disease Associated with Chronic Kidney Disease.

Fibroblast growth factor 23 (FGF23) levels are often elevated in chronic kidney disease (CKD). FGF23 and inflammation are common characteristics in CKD, and both are associated with worse disease progression and the occurrence of complications. The existence of an interaction between FGF23 and inflammation has been suggested, each of which influences the expression and activity of the other, leading to a vicious feedback loop with adverse outcomes, including cardiovascular disease and mortality. In this work, we determined circulating FGF23 levels in a group of patients with CKD stages 3 and 4 subjected to elective femoral endarterectomy due to established peripheral artery disease (PAD), a condition resulting from an athero-inflammatory process, and we studied its associations with different inflammatory markers and mediators. We evaluated its association with serum tumor necrosis factor (TNF)α, interleukin (IL) 6, and IL10, as well as with the gene expression levels of these parameters and A disintegrin and metalloproteinase domain-containing protein (ADAM) 17 in femoral vascular tissue and peripheral blood circulating cells (PBCCs). We also analyzed its association with serum concentrations of C-reactive protein (CRP), the systemic immune inflammation index (SII), and the neutrophil-to-lymphocyte ratio (NLR). Finally, we determined the vascular immunoreactivity of protein TNFα in a subgroup of patients. FGF23 concentrations were independently associated with circulating and PBCC mRNA levels of TNFα. Worst kidney function and diabetes were also found to be contributing to FGF23 levels. Patients with higher levels of FGF23 also had greater vascular immunoreactivity for TNFα.

Regulation of Mertk Surface Expression via ADAM17 and γ-Secretase Proteolytic Processing.

Mertk, a type I receptor tyrosine kinase and member of the TAM family of receptors, has important functions in promoting efferocytosis and resolving inflammation under physiological conditions. In recent years, Mertk has also been linked to pathophysiological roles in cancer, whereby, in several cancer types, including solid cancers and leukemia/lymphomas. Mertk contributes to oncogenic features of proliferation and cell survival as an oncogenic tyrosine kinase. In addition, Mertk expressed on macrophages, including tumor-associated macrophages, promotes immune evasion in cancer and is suggested to act akin to a myeloid checkpoint inhibitor that skews macrophages towards inhibitory phenotypes that suppress host T-cell anti-tumor immunity. In the present study, to better understand the post-translational regulation mechanisms controlling Mertk expression in monocytes/macrophages, we used a PMA-differentiated THP-1 cell model to interrogate the regulation of Mertk expression and developed a novel Mertk reporter cell line to study the intracellular trafficking of Mertk. We show that PMA treatment potently up-regulates Mertk as well as components of the ectodomain proteolytic processing platform ADAM17, whereas PMA differentially regulates the canonical Mertk ligands Gas6 and Pros1 (Gas6 is down-regulated and Pros1 is up-regulated). Under non-stimulated homeostatic conditions, Mertk in PMA-differentiated THP1 cells shows active constitutive proteolytic cleavage by the sequential activities of ADAM17 and the Presenilin/γ-secretase complex, indicating that Mertk is cleaved homeostatically by the combined sequential action of ADAM17 and γ-secretase, after which the cleaved intracellular fragment of Mertk is degraded in a proteasome-dependent mechanism. Using chimeric Flag-Mertk-EGFP-Myc reporter receptors, we confirm that inhibitors of γ-secretase and MG132, which inhibits the 26S proteasome, stabilize the intracellular fragment of Mertk without evidence of nuclear translocation. Finally, the treatment of cells with active γ-carboxylated Gas6, but not inactive Warfarin-treated non-γ-carboxylated Gas6, regulates a distinct proteolytic itinerary-involved receptor clearance and lysosomal proteolysis. Together, these results indicate that pleotropic and complex proteolytic activities regulate Mertk ectodomain cleavage as a homeostatic negative regulatory event to safeguard against the overactivation of Mertk.

iRhom2 regulates ectodomain shedding and surface expression of the major histocompatibility complex (MHC) class I.

Proteolytic release of transmembrane proteins from the cell surface, the so called ectodomain shedding, is a key process in inflammation. Inactive rhomboid 2 (iRhom2) plays a crucial role in this context, in that it guides maturation and function of the sheddase ADAM17 (a disintegrin and metalloproteinase 17) in immune cells, and, ultimately, its ability to release inflammatory mediators such as tumor necrosis factor α (TNFα). Yet, the macrophage sheddome of iRhom2/ADAM17, which is the collection of substrates that are released by the proteolytic complex, is only partly known. In this study, we applied high-resolution proteomics to murine and human iRhom2-deficient macrophages for a systematic identification of substrates, and therefore functions, of the iRhom2/ADAM17 proteolytic complex. We found that iRhom2 loss suppressed the release of a group of transmembrane proteins, including known (e.g. CSF1R) and putative novel ADAM17 substrates. In the latter group, shedding of major histocompatibility complex class I molecules (MHC-I) was consistently reduced in both murine and human macrophages when iRhom2 was ablated. Intriguingly, it emerged that in addition to its shedding, iRhom2 could also control surface expression of MHC-I by an undefined mechanism. We have demonstrated the biological significance of this process by using an in vitro model of CD8+ T-cell (CTL) activation. In this model, iRhom2 loss and consequent reduction of MHC-I expression on the cell surface of an Epstein-Barr virus (EBV)-transformed lymphoblastoid cell line dampened activation of autologous CTLs and their cell-mediated cytotoxicity. Taken together, this study uncovers a new role for iRhom2 in controlling cell surface levels of MHC-I by a dual mechanism that involves regulation of their surface expression and ectodomain shedding.

Pathological mutations reveal the key role of the cytosolic iRhom2 N-terminus for phosphorylation-independent 14-3-3 interaction and ADAM17 binding, stability, and activity.

The protease ADAM17 plays an important role in inflammation and cancer and is regulated by iRhom2. Mutations in the cytosolic N-terminus of human iRhom2 cause tylosis with oesophageal cancer (TOC). In mice, partial deletion of the N-terminus results in a curly hair phenotype (cub). These pathological consequences are consistent with our findings that iRhom2 is highly expressed in keratinocytes and in oesophageal cancer. Cub and TOC are associated with hyperactivation of ADAM17-dependent EGFR signalling. However, the underlying molecular mechanisms are not understood. We have identified a non-canonical, phosphorylation-independent 14-3-3 interaction site that encompasses all known TOC mutations. Disruption of this site dysregulates ADAM17 activity. The larger cub deletion also includes the TOC site and thus also dysregulated ADAM17 activity. The cub deletion, but not the TOC mutation, also causes severe reductions in stimulated shedding, binding, and stability of ADAM17, demonstrating the presence of additional regulatory sites in the N-terminus of iRhom2. Overall, this study contrasts the TOC and cub mutations, illustrates their different molecular consequences, and reveals important key functions of the iRhom2 N-terminus in regulating ADAM17.

Mesenchymal Transglutaminase 2 Activates Epithelial ADAM17: Link to G-Protein-Coupled Receptor 56 (ADGRG1) Signalling.

A wound healing model was developed to elucidate the role of mesenchymal-matrix-associated transglutaminase 2 (TG2) in keratinocyte re-epithelialisation. TG2 drives keratinocyte migratory responses by activation of disintegrin and metalloproteinase 17 (ADAM17). We demonstrate that epidermal growth factor (EGF) receptor ligand shedding leads to EGFR-transactivation and subsequent rapid keratinocyte migration on TG2-positive ECM. In contrast, keratinocyte migration was impaired in TG2 null conditions. We show that keratinocytes express the adhesion G-protein-coupled receptor, ADGRG1 (GPR56), which has been proposed as a TG2 receptor. Using ADAM17 activation as a readout and luciferase reporter assays, we demonstrate that TG2 activates GPR56. GPR56 activation by TG2 reached the same level as observed with an agonistic N-GPR56 antibody. The N-terminal GPR56 domain is required for TG2-regulated signalling response, as the constitutively active C-GPR56 receptor was not activated by TG2. Signalling required the C-terminal TG2 ß-barrel domains and involved RhoA-associated protein kinase (ROCK) and ADAM17 activation, which was blocked by specific inhibitors. Cell surface binding of TG2 to the N-terminal GPR56 domain is rapid and is associated with TG2 and GPR56 endocytosis. TG2 and GPR56 represent a ligand receptor pair causing RhoA and EGFR transactivation. Furthermore, we determined a binding constant for the interaction of human TG2 with N-GPR56 and show for the first time that only the calcium-enabled "open" TG2 conformation associates with N-GPR56.

MiR-145-5p reduced ANG II-induced ACE2 shedding and the inflammatory response in alveolar epithelial cells by targeting ADAM17 and inhibiting the AT1R/ADAM17 pathway.

The excessive elevation of angiotensin II (ANG II) is closely associated with the occurrence and development of aortic dissection (AD)-related acute lung injury (ALI), through its binding to angiotensin II receptor type I (AT1R). MiR-145-5p is a noncoding RNA that can be involved in a variety of cellular physiopathological processes. Transfection with miR-145-5p was found to downregulated the expression of A disintegrin and metalloprotease 17 (ADAM17) and reduced the levels of angiotensin-converting enzyme 2 (ACE2) in lung tissue, while concurrently increasing plasma ACE2 levels in the AD combined with ALI mice. ADAM17 was proved to be a target of miR-145-5p. Transfection with miR-145-5p decreased the shedding of ACE2 and alleviated the inflammatory response induced by ANG II through targeting ADAM17 and inhibiting the AT1R/ADAM17 pathway in A549 cells. In conclusion, our present study demonstrates the role and mechanism of miR-145-5p in alleviating ANG II-induced acute lung injury, providing a new insight into miRNA therapy for reducing lung injury in patients with aortic dissection.

MiR-145 Alleviates Sepsis-Induced Inflammatory Responses and Organ Injury by Targeting ADAM17.

BACKGROUND: Current studies have demonstrated that disintegrin and metalloproteinase 17 (ADAM17) plays a critical role in the pathogenesis of sepsis. MicroRNA (miR)-145 is known to control immune responses as an anti-inflammatory modulatory molecule. However, a fundamental understanding of how miR-145 regulates ADAM17 and, more broadly, sepsis-induced inflammatory response remains unknown. METHODS: We used western blotting and quantitative real-time PCR (qRT-PCR) to measure expression levels of ADAM17 and miR-145. Enzyme-linked immunosorbent assays (ELISA) were performed to measure cytokine production. To determine if ADAM17 is a target gene of miR-145, bioinformatics analyses and luciferase reporter assays were conducted. The impacts of ADAM17 and miR-145 on sepsis-induced inflammatory responses were accessed in vitro using human umbilical endothelial cells (HUVECs) treated with lipopolysaccharide (LPS). Sepsis-induced inflammatory response was measured in vivo using a polymicrobial septic mouse model induced by cecal ligation and puncture (CLP) with pre-injection of a miR-145 agomir. RESULTS: In HUVECs treated with LPS, miR-145 expression was downregulated and miR-145 negatively regulated ADAM17 expression through direct binding to the ADAM17 transcript 3'-UTR. MiR-145 overexpression markedly reduced LPS-induced inflammatory cytokine production by targeting ADAM17 in HUVECs. In comparison to CLP-induced septic mice treated with a control agomir, treatment with a miR-145 agomir significantly reduced the expression of ADAM17, numerous downstream cytokines such as IL-6, TNF-α, IL-1ß and MCP-1, and the endothelial injury factors ICAM-1, VCAM-1. The miR-145 agomir also alleviated acute lung and kidney injury and improved the survival rate of septic mice. CONCLUSIONS: This study showed that miR-145, by specifically targeting ADAM17, negatively regulates sepsis-induced inflammatory responses and vascular endothelial injury, and ultimately improved organ injury and survival during sepsis. The underlying mechanism for the regulation of ADAM17 expression by miR-145 and sepsis-induced inflammatory reactions may offer sepsis patients a novel therapeutic option.

The protease ADAM17 at the crossroads of disease: revisiting its significance in inflammation, cancer, and beyond.

The protease A Disintegrin And Metalloproteinase 17 (ADAM17) plays a central role in the pathophysiology of several diseases. ADAM17 is involved in the cleavage and shedding of at least 80 known membrane-tethered proteins, which subsequently modulate several intracellular signaling pathways, and therefore alter cell behavior. Dysregulated expression and/or activation of ADAM17 has been linked to a wide range of autoimmune and inflammatory diseases, cancer, and cardiovascular disease. In this review, we provide an overview of the current state of knowledge from preclinical models and clinical data on the diverse pathophysiological roles of ADAM17, and discuss the mechanisms underlying ADAM17-mediated protein shedding and the potential therapeutic implications of targeting ADAM17 in these diseases.

m6A­modified HOXC10 promotes HNSCC progression via co­activation of ADAM17/EGFR and Wnt/ß­catenin signaling.

The homeobox (HOX) gene family plays a fundamental role in carcinogenesis. However, the oncogenic mechanism of HOXC10 in head and neck squamous cell carcinoma (HNSCC) remains unclear. In the present study, it was revealed that HOXC10 expression was significantly higher in HNSCC tissues than in adjacent tissues, and a high level of HOXC10 was closely associated with worse clinical outcomes. HOXC10 overexpression promoted HNSCC cell proliferation, migration, and invasion, both in vitro and in vivo. Mechanistically, chromatin immunoprecipitation sequencing revealed that HOXC10 drove the transcriptional activation of a disintegrin and metalloproteinase 17 (ADAM17), and the ADAM17/epidermal growth factor receptor (EGFR)/ERK1/2 signaling pathway facilitating the proliferation of HNSCC. Furthermore, mass spectrometric analysis indicated that HOXC10 interacted with ribosomal protein S15A (RPS15A) and enhanced RPS15A protein expression, activating the Wnt/ß­catenin pathway and contributing to invasion and metastasis of HNSCC. Additionally, the methylated RNA immune precipitation and RNA antisense purification assays showed that N6­methyladenosine (m6A) writer, methyltransferase­like 3, catalyzed m6A modification of the HOXC10 transcript, m6A reader insulin like growth factor 2 mRNA binding protein (IGF2BP)1 and IGF2BP3 involved in recognizing and stabilizing m6A­tagged HOXC10 mRNA. In summary, the present study identified HOXC10 as a promising candidate oncogene in HNSCC. The m6A modification­mediated HOXC10 promoted proliferation, migration, and invasion of HNSCC through co­activation of ADAM17/EGFR and Wnt/ß­catenin signaling, providing a novel diagnostic and prognostic biomarker and a potential therapeutic target for HNSCC.

Predictive Roles of ADAM17 in Patient Survival and Immune Cell Infiltration in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the deadliest malignant tumour worldwide. The metalloproteinase ADAM17 is associated with tumour formation and development; however, its significance in HCC is unclear. This study aimed to investigate the role of ADAM17 in HCC and the correlation between its expression and immune cell infiltration. ADAM17 expression was analysed in pan-cancer and HCC tissues using The Cancer Genome Atlas and Genotype-Tissue Expression datasets. Kaplan-Meier survival analysis displayed a negative association between ADAM17 expression and the overall survival of patients with HCC. High ADAM17 expression was linked to poor tumour/node (T/N) stage and alpha fetoprotein (AFP) levels. Gene Set Enrichment Analysis, Gene Ontology, and Kyoto Encyclopaedia of Genes and Genomes analyses revealed the enrichment of several pathways, including epithelial-mesenchymal transition, inflammatory response, Hedgehog, and KRAS signalling, in patients with upregulated ADAM17. ADAM17 was shown to be positively correlated with immune cell infiltration and immune checkpoint expression via the Tumour Immune Estimation Resource (TIMER) database and immunohistochemistry analyses. Protein-protein interaction (PPI) network analysis revealed that ADAM17 plays a core role in cancer development and immune evasion. In vitro and in vivo experiments demonstrated that ADAM17 influences HCC growth and metastasis. In conclusion, ADAM17 is upregulated in most cancers, particularly HCC, and is critical in the development and immune evasion of HCC.

Genetic Predisposition to Elevated Levels of Circulating ADAM17 Is Associated with the Risk of Severe COVID-19.

High levels of ADAM17 activity have emerged as an important mediator in severe COVID-19. This study aims to characterize eventual causal relationships between ADAM17 and COVID-19. Using Mendelian randomization analyses, we examined the causal effects of circulating ADAM17 on COVID-19 outcomes using summary statistics from large, genome-wide association studies of ADAM17 (up to 35,559 individuals) from the Icelandic Cancer Project and deCODE genetics, as well as critically ill COVID-19 patients (cases: 13,769; controls: 1,072,442), hospitalized COVID-19 patients (cases: 32,519; controls: 2,062,805) and reported SARS-CoV-2 infections (cases: 122,616; controls: 2,475,240) from the COVID-19 Host Genetics Initiative. The Mendelian randomization (MR) analyses demonstrated that a 1 standard deviation increase in genetically determined circulating ADAM17 (extracellular domain) was associated with an increased risk of developing critical ill COVID-19 (odds ratio [OR] = 1.26, 95% confidence interval [CI]:1.03-1.55). The multivariable MR analysis suggested a direct causal role of circulating ADAM17 (extracellular domain) in the risk of developing critical COVID-19 (OR = 1.09; 95% CI:1.01-1.17) when accounting for body mass index. No causal effect for the cytoplasmic domain of ADAM17 on COVID-19 was observed. Our results suggest that an increased genetic susceptibility to elevated levels of circulating ADAM17 (extracellular domain) is associated with a higher risk of suffering from severe COVID-19, strengthening the idea that the timely selective inhibition of ADAM17 could be a potential therapeutic target worthy of investigation.

ADAM17 targeting by human cytomegalovirus remodels the cell surface proteome to simultaneously regulate multiple immune pathways.

Human cytomegalovirus (HCMV) is a major human pathogen whose life-long persistence is enabled by its remarkable capacity to systematically subvert host immune defenses. In exploring the finding that HCMV infection up-regulates tumor necrosis factor receptor 2 (TNFR2), a ligand for the pro-inflammatory antiviral cytokine TNFα, we found that the underlying mechanism was due to targeting of the protease, A Disintegrin And Metalloproteinase 17 (ADAM17). ADAM17 is the prototype 'sheddase', a family of proteases that cleaves other membrane-bound proteins to release biologically active ectodomains into the supernatant. HCMV impaired ADAM17 surface expression through the action of two virally-encoded proteins in its UL/b' region, UL148 and UL148D. Proteomic plasma membrane profiling of cells infected with an HCMV double-deletion mutant for UL148 and UL148D with restored ADAM17 expression, combined with ADAM17 functional blockade, showed that HCMV stabilized the surface expression of 114 proteins (P < 0.05) in an ADAM17-dependent fashion. These included reported substrates of ADAM17 with established immunological functions such as TNFR2 and jagged1, but also numerous unreported host and viral targets, such as nectin1, UL8, and UL144. Regulation of TNFα-induced cytokine responses and NK inhibition during HCMV infection were dependent on this impairment of ADAM17. We therefore identify a viral immunoregulatory mechanism in which targeting a single sheddase enables broad regulation of multiple critical surface receptors, revealing a paradigm for viral-encoded immunomodulation.

Ectodomain Shedding by ADAM17 Increases the Release of Soluble CD40 from Human Endothelial Cells under Pro-Inflammatory Conditions.

BACKGROUND: Homozygosity for the C allele of the -1T>C single nucleotide polymorphism (SNP) of the CD40 gene (rs1883832) is associated with susceptibility to coronary heart disease (CHD), enhanced CD40 expression, and shedding. The disintegrin metalloprotease ADAM17 can cleave various cell surface proteins. This study investigates an association between ADAM17-mediated CD40 shedding and inflammation in CC genotype human endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVEC) carrying the CC genotype were stimulated with soluble CD40 ligand (sCD40L) or tumor necrosis factor-α (TNFα). Messenger RNA and protein expression were determined with standard methods. Levels of high sensitive c-reactive protein (hs-CRP), interleukin-6 (IL-6), and sCD40 in plasma samples from patients with CHD were assessed using ELISA. RESULTS: ADAM17 surface abundance was elevated following stimulation with CD40L and TNFα just as its regulator iRhom2. Inhibition of ADAM17 prevented TNFα-induced sCD40 and soluble vascular cell adhesion molecule-1 release into the conditioned medium and reinforced CD40 surface abundance. Secondary to inhibition of ADAM17, stimulation with CD40L or TNFα upregulated monocyte chemoattractant protein-1 mRNA and protein. Levels of sCD40 and the inflammatory biomarkers hs-CRP and IL-6 were positively correlated in the plasma of patients with CHD. CONCLUSIONS: We provide a mechanism by which membrane-bound CD40 is shed from the endothelial cell surface by ADAM17, boosting sCD40 formation and limiting downstream CD40 signaling. Soluble CD40 may represent a robust biomarker for CHD, especially in conjunction with homozygosity for the C allele of the -1T>C SNP of the CD40 gene.

Analysis of the function of ADAM17 in iRhom2 curly-bare and tylosis with esophageal cancer mutant mice.

Tylosis with oesophageal cancer (TOC) is a rare familial disorder caused by cytoplasmic mutations in inactive rhomboid 2 (iRhom2 or iR2, encoded by Rhbdf2). iR2 and the related iRhom1 (or iR1, encoded by Rhbdf1) are key regulators of the membrane-anchored metalloprotease ADAM17, which is required for activating EGFR ligands and for releasing pro-inflammatory cytokines such as TNFα (or TNF). A cytoplasmic deletion in iR2, including the TOC site, leads to curly coat or bare skin (cub) in mice, whereas a knock-in TOC mutation (toc) causes less severe alopecia and wavy fur. The abnormal skin and hair phenotypes of iR2cub/cub and iR2toc/toc mice depend on amphiregulin (Areg) and Adam17, as loss of one allele of either gene rescues the fur phenotypes. Remarkably, we found that iR1-/- iR2cub/cub mice survived, despite a lack of mature ADAM17, whereas iR2cub/cub Adam17-/- mice died perinatally, suggesting that the iR2cub gain-of-function mutation requires the presence of ADAM17, but not its catalytic activity. The iR2toc mutation did not substantially reduce the levels of mature ADAM17, but instead affected its function in a substrate-selective manner. Our findings provide new insights into the role of the cytoplasmic domain of iR2 in vivo, with implications for the treatment of TOC patients.

Mechanical activation of lung epithelial cells through the ion channel Piezo1 activates the metalloproteinases ADAM10 and ADAM17 and promotes growth factor and adhesion molecule release.

In the lung, pulmonary epithelial cells undergo mechanical stretching during ventilation. The associated cellular mechanoresponse is still poorly understood at the molecular level. Here, we demonstrate that activation of the mechanosensitive cation channel Piezo1 in a human epithelial cell line (H441) and in primary human lung epithelial cells induces the proteolytic activity of the metalloproteinases ADAM10 and ADAM17 at the plasma membrane. These ADAMs are known to convert cell surface expressed proteins into soluble and thereby play major roles in proliferation, barrier regulation and inflammation. We observed that chemical activation of Piezo1 promotes cleavage of substrates that are specific for either ADAM10 or ADAM17. Activation of Piezo1 also induced the synthesis and ADAM10/17-dependent release of the growth factor amphiregulin (AREG). In addition, junctional adhesion molecule A (JAM-A) was shed in an ADAM10/17-dependent manner resulting in a reduction of cell contacts. Stretching experiments combined with Piezo1 knockdown further demonstrated that mechanical activation promotes shedding via Piezo1. Most importantly, high pressure ventilation of murine lungs increased AREG and JAM-A release into the alveolar space, which was reduced by a Piezo1 inhibitor. Our study provides a novel link between stretch-induced Piezo1 activation and the activation of ADAM10 and ADAM17 in lung epithelium. This may help to understand acute respiratory distress syndrome (ARDS) which is induced by ventilation stress and goes along with perturbed epithelial permeability and release of growth factors.

ADAM17 Confers Temozolomide Resistance in Human Glioblastoma Cells and miR-145 Regulates Its Expression.

Glioblastoma (GBM) is a malignant brain tumor, commonly treated with temozolomide (TMZ). Upregulation of A disintegrin and metalloproteinases (ADAMs) is correlated to malignancy; however, whether ADAMs modulate TMZ sensitivity in GBM cells remains unclear. To explore the role of ADAMs in TMZ resistance, we analyzed changes in ADAM expression following TMZ treatment using RNA sequencing and noted that ADAM17 was markedly upregulated. Hence, we established TMZ-resistant cell lines to elucidate the role of ADAM17. Furthermore, we evaluated the impact of ADAM17 knockdown on TMZ sensitivity in vitro and in vivo. Moreover, we predicted microRNAs upstream of ADAM17 and transfected miRNA mimics into cells to verify their effects on TMZ sensitivity. Additionally, the clinical significance of ADAM17 and miRNAs in GBM was analyzed. ADAM17 was upregulated in GBM cells under serum starvation and TMZ treatment and was overexpressed in TMZ-resistant cells. In in vitro and in vivo models, ADAM17 knockdown conferred greater TMZ sensitivity. miR-145 overexpression suppressed ADAM17 and sensitized cells to TMZ. ADAM17 upregulation and miR-145 downregulation in clinical specimens are associated with disease progression and poor prognosis. Thus, miR-145 enhances TMZ sensitivity by inhibiting ADAM17. These findings offer insights into the development of therapeutic approaches to overcome TMZ resistance.

Disruption of the ADAM17/NF-κB feedback loop in astrocytes ameliorates HIV-1 Tat-induced inflammatory response and neuronal death.

A disintegrin and metalloproteinases (ADAMs) are involved in multiple neurodegenerative diseases. However, the roles and mechanisms of ADAMs in HIV-associated neurocognitive disorder (HAND) remain unclear. Transactivator of transcription (Tat) induces inflammatory response in astrocytes, thereby leading to neuronal apoptosis in the central nervous system. In this study, we determined that ADAM17 expression was upregulated during soluble Tat stimulus in HEB astroglial cells. Inhibition of ADAM17 suppressed Tat-induced pro-inflammatory cytokines production and rescued the astrocytes-derived conditioned media (ACM)-mediated SH-SY5Y neural cells apoptosis. Moreover, ADAM17 mediated Tat-triggered inflammatory response in a NF-κB-dependent manner. Conversely, Tat induced ADAM17 expression via NF-κB signaling pathway. In addition, pharmacological inhibition of NF-κB signaling inhibited Tat-induced inflammatory response, which could be rescued by overexpression of ADAM17. Taken together, our study clarifies the potential role of the ADAM17/NF-κB feedback loop in Tat-induced inflammatory response in astrocytes and the ACM-mediated neuronal death, which could be a novel therapeutic target for relief of HAND.

MiR-26a-5p from HucMSC-derived extracellular vesicles inhibits epithelial mesenchymal transition by targeting Adam17 in silica-induced lung fibrosis.

Silicosis is one of several potentially fatal occupational pathologies caused by the prolonged inhalation of respirable crystalline silica. Previous studies have shown that lung epithelial-mesenchymal transition (EMT) plays a significant role in the fibrosis effect of silicosis. Human umbilical cord mesenchymal stem cells-derived Extracellular vesicles (hucMSC-EVs) have attracted great interest as a potential therapy of EMT and fibrosis-related diseases. However, the potential effects of hucMSC-EVs in inhibiting EMT in silica-induced fibrosis, as well as its underlying mechanisms, remain largely unknown. In this study, we used the EMT model in MLE-12 cells and observed the effects and mechanism of hucMSC-EVs inhibition of EMT. The results revealed that hucMSC-EVs can indeed inhibit EMT. MiR-26a-5p was highly enriched in hucMSC-EVs but was down-regulated in silicosis mice. We found that miR-26a-5p in hucMSC-EVs was over-expressed after transfecting miR-26a-5p expressing lentivirus vectors into hucMSCs. Subsequently, we explored if miR-26a-5p, attained from hucMSC-EVs, was involved in inhibiting EMT in silica-induced lung fibrosis. Our findings suggested that hucMSC-EVs could deliver miR-26a-5p into MLE-12 cells and cause the inhibition of the Adam17/Notch signalling pathway to ameliorate EMT in silica-induced pulmonary fibrosis. These findings might represent a novel insight into treating silicosis fibrosis.

ARPC5 is transcriptionally activated by KLF4, and promotes cell migration and invasion in prostate cancer via up-regulating ADAM17 : ARPC5 serves as an oncogene in prostate cancer.

BACKGROUND: Prostate cancer (PCa) is one of the most common cancers in men worldwide. Actin-related protein 2/3 complex subunit 5 (ARPC5) has been validated as a critical regulator in several kinds of human tumors. However, whether ARPC5 is implicated in PCa progression remains largely unknown. METHODS: PCa specimens and PCa cell lines were obtained for detecting gene expressions using western blot and quantitative reverse transcriptase PCR (qRT-PCR). PCa cells transfected with ARPC5 shRNA or a disintegrin and metalloprotease 17 (ADAM17) overexpressed plasmids were harvested for assessing cell proliferation, migration and invasion by using cell counting kit-8 (CCK-8), colony formation and transwell assays, respectively. The interaction relationship between molecules was testified with chromatin immunoprecipitation and luciferase reporter assay. Xenograft mice model was conducted for confirming the role of ARPC5/ADAM17 axis in vivo. RESULTS: Upregulated ARPC5 was observed in PCa tissues and cells, as well as forecasted poor prognosis of PCa patients. Depletion of ARPC5 inhibited PCa cell proliferation, migration and invasion. Krüppel-like factor 4 (KLF4) was identified to be a transcriptional activator of ARPC5 via binding with its promoter region. Furthermore, ADAM17 served as a downstream effector of ARPC5. ADAM17 overexpression overturned ARPC5 knockdown-induced repressive impacts on PCa progression in vitro and in vivo. CONCLUSION: Collectively, ARPC5 was activated by KLF4 and upregulated ADAM17 to promote PCa progression, which might act as a promising therapeutic target and prognostic biomarker for PCa.