Tumor Necrosis Factor-α Converting Enzyme Research Articles

TGF-α/EGFR signaling promotes lipopolysaccharide-induced abnormal elastin deposition and alveolar simplification

Bronchopulmonary dysplasia (BPD) is characterized by shortened secondary septa and fewer, larger alveoli. Elastin deposition to the distal tips of the secondary septa is critical for elongation of the secondary septa. Alveolar myofibroblasts, which are thought to migrate to the septal tips during alveolarization, are mainly responsible for elastin production and deposition. Antenatal exposure to inflammation induces abnormal elastin deposition, thereby increasing the risk of developing BPD. Here, we found that lipopolysaccharide (LPS) significantly increased the expression of transforming growth factor-α (TGF-α) in an LPS-induced rat model of BPD and in LPS-treated human pulmonary epithelial cells (BEAS-2B). In addition, in vitro experiments suggested that LPS upregulated TGF-α expression via toll-like receptor 4 (TLR4)/tumor necrosis factor α-converting enzyme (TACE) signaling. Increased TGF-α levels via its receptor epidermal growth factor receptor (EGFR)-induced lysyl oxidase (LOX) overactivation and cell division cycle 42 (Cdc42) activity inhibition of myofibroblasts. Similarly, in vivo LOX overactivation and inhibition of Cdc42 activity were observed in the lungs of LPS-exposed pups. LOX overactivation led to abnormal elastin deposition, and inhibition of Cdc42 activity disturbed the directional migration of myofibroblasts and disrupted elastin localization. Most importantly, the EGFR inhibitor erlotinib partially rescued LOX overactivation and Cdc42 activity inhibition, and improved elastin deposition and alveolar development in antenatal LPS-treated rats. Taken together, our data suggest that TGF-α/EGFR signaling is critically involved in the regulation of elastin deposition and represents a novel therapeutic target.

Exposure to Low-Intensity Blast Increases Clearance of Brain Amyloid Beta.

The long-term effects of exposure to blast overpressure are an important health concern in military personnel. Increase in amyloid beta (Aβ) has been documented after non-blast traumatic brain injury (TBI) and may contribute to neuropathology and an increased risk for Alzheimer's disease. We have shown that Aβ levels decrease following exposure to a low-intensity blast overpressure event. To further explore this observation, we examined the effects of a single 37 kPa (5.4 psi) blast exposure on brain Aβ levels, production, and clearance mechanisms in the acute (24 h) and delayed (28 days) phases post-blast exposure in an experimental rat model. Aβ and, notably, the highly neurotoxic detergent soluble Aβ42 form, was reduced at 24 h but not 28 days after blast exposure. This reduction was not associated with changes in the levels of Aβ oligomers, expression levels of amyloid precursor protein (APP), or increase in enzymes involved in the amyloidogenic cleavage of APP, the β- and ϒ-secretases BACE1 and presenilin-1, respectively. The levels of ADAM17 α-secretase (also known as tumor necrosis factor α-converting enzyme) decreased, concomitant with the reduction in brain Aβ. Additionally, significant increases in brain levels of the endothelial transporter, low-density related protein 1 (LRP1), and enhancement in co-localization of aquaporin-4 (AQP4) to perivascular astrocytic end-feet were observed 24 h after blast exposure. These findings suggest that exposure to low-intensity blast may enhance endothelial clearance of Aβ by LRP1-mediated transcytosis and alter AQP4-aided glymphatic clearance. Collectively, the data demonstrate that low-intensity blast alters enzymatic, transvascular, and perivascular clearance of Aβ.

The mechanism by which cannabidiol (CBD) suppresses TNF-α secretion involves inappropriate localization of TNF-α converting enzyme (TACE)

Cannabidiol (CBD) is a phytocannabinoid derived from Cannabis sativa that exerts anti-inflammatory mechanisms. CBD is being examined for its putative effects on the neuroinflammatory disease, multiple sclerosis (MS). One of the major immune mediators that propagates MS and its mouse model experimental autoimmune encephalomyelitis (EAE) are macrophages. Macrophages can polarize into an inflammatory phenotype (M1) or an anti-inflammatory phenotype (M2a). Therefore, elucidating the impact on macrophage polarization with CBD pre-treatment is necessary to understand its anti-inflammatory mechanisms. To study this effect, murine macrophages (RAW 264.7) were pre-treated with CBD (10 µM) or vehicle (ethanol 0.1 %) and were either left untreated (naive; cell media only), or stimulated under M1 (IFN-γ + lipopolysaccharide, LPS) or M2a (IL-4) conditions for 24 hr. Cells were analyzed for macrophage polarization markers, and supernatants were analyzed for cytokines and chemokines. Immunofluorescence staining was performed on M1-polarized cells for the metalloprotease, tumor necrosis factor-α-converting enzyme (TACE), as this enzyme is responsible for the secretion of TNF-α. Overall results showed that CBD decreased several markers associated with the M1 phenotype while exhibiting less effects on the M2a phenotype. Significantly, under M1 conditions, CBD increased the percentage of intracellular and surface TNF-α but decreased secreted TNF-α. This phenomenon might be mediated by TACE as staining showed that CBD sequestered TACE intracellularly. CBD also prevented RelA nuclear translocation. These results suggest that CBD may exert its anti-inflammatory effects by reducing M1 polarization and decreasing TNF-α secretion via inappropriate localization of TACE and RelA.

S-1-propenyl-L-cysteine suppresses lipopolysaccharide-induced expression of matrix metalloproteinase-1 through inhibition of tumor necrosis factor-α converting enzyme-epidermal growth factor receptor axis in human gingival fibroblasts.

Periodontal disease is the most common dental health problem characterized by the destruction of connective tissue and the resorption of alveolar bone resulting from a chronic infection associated with pathogenic bacteria in the gingiva. Aged garlic extract has been reported to improve gingival bleeding index and probing pocket depth score in patients with mild to moderate periodontitis. Although our previous study found that aged garlic extract and its constituents suppressed the tumor necrosis factor-α-induced inflammatory responses in a human gingival epithelial cell line, the mechanism underlying the effect of aged garlic extract on the destruction of the gingiva remains unclear. The present study investigated the effect of S-1-propenyl-L-cysteine, one of the major sulfur bioactive compounds in aged garlic extract, on the lipopolysaccharide-induced expression of matrix metalloproteinases in human gingival fibroblasts HGF-1 cells. Matrix metalloproteinases are well known to be closely related to the destruction of the gingiva. We found that S-1-propenyl-L-cysteine suppressed the lipopolysaccharide-induced expression and secretion of matrix metalloproteinase-1 in HGF-1 cells. In addition, S-1-propenyl-L-cysteine inhibited the lipopolysaccharide-induced phosphorylation of epidermal growth factor receptor and expression of the active form of tumor necrosis factor-α converting enzyme. Furthermore, the inhibitors of epidermal growth factor receptor tyrosine kinase and tumor necrosis factor-α converting enzyme, AG-1478 and TAPI-1, respectively, reduced the lipopolysaccharide-induced protein level of matrix metalloproteinase-1, as did S-1-propenyl-L-cysteine. Taken together, these results suggested that S-1-propenyl-L-cysteine suppresses the lipopolysaccharide-induced expression of matrix metalloproteinase-1 through the blockade of the tumor necrosis factor-α converting enzyme-epidermal growth factor receptor axis in gingival fibroblasts.

Effects of Resveratrol on Tight Junction Proteins and the Notch1 Pathway in an HT-29 Cell Model of Inflammation Induced by Lipopolysaccharide.

Ulcerative colitis (UC) is closely associated with disruption of intestinal epithelial tight junction proteins. A variety of studies have confirmed that resveratrol (RSV), a natural polyphenolic compound, has a potential anti-inflammatory effect and can regulate the expression of tight junction proteins. However, the mechanism by which RSV regulates the expression of tight junction proteins in the intestinal epithelium remains unclear. Therefore, we investigated the potential effect of RSV on tight junction proteins in an HT-29 cell model of inflammation induced by lipopolysaccharide (LPS) and explored its mechanism of action. First, the downregulated expression of the tight junction proteins occludin, ZO-1, and claudin-1 in the HT-29 cell model of inflammation induced by LPS was reversed by incubation with RSV, accompanied by a decrease in the expression of tumor necrosis factor α-converting enzyme (TACE). Additionally, the Notch1 pathway was attenuated and the expression of the inflammatory factors IL-6 and TNF-α was decreased by treatment with RSV. Second, after Jagged-1 was used in combination with RSV to reactivate the Notch1 pathway, the protective effects of RSV against the LPS-induced reductions in the expression of the tight junction proteins occludin, ZO-1, and claudin-1 and the decreases in the levels of the inflammatory factors IL-6 and TNF-α were abolished. These results suggest that RSV might regulate the expression of tight junction proteins by attenuating the Notch1 pathway.

Celecoxib, Glipizide, Lapatinib, and Sitagliptin as potential suspects of aggravating SARS-CoV-2 (COVID-19) infection: a computational approach

COVID-19 caused by SARS-CoV-2 has emerged as a potential threat to human life, especially to people suffering from chronic diseases. In this study, we investigated the ability of selected FDA-approved drugs to inhibit TACE (tumor necrosis factor α converting enzyme), which is responsible for the shedding of membrane-bound ACE2 (angiotensin-converting enzyme2) receptors into soluble ACE2. The inhibition of TACE would lead to an increased population of membrane-bound ACE2, which would facilitate ACE2-Spike protein interaction and viral entry. A total of 50 drugs prescribed in treating various chronic diseases in Saudi Arabia were screened by performing molecular docking using AutoDock4.2. Based on docking energy (≤ −9.00 kcal mol−1), four drugs (Celecoxib, Glipizide, Lapatinib, and Sitagliptin) were identified as potential inhibitors of TACE, with binding affinities up to 106–107 M −1. Analysis of the molecular docking suggests that these drugs were bound to TACE's catalytic domain and interact with the key residues such as His405, Glu406, and His415, which are involved in active site Zn2+ ion chelation. Molecular dynamics simulation was performed to confirm the stability of TACE-drugs complexes. RMSD (root mean square deviation), RMSF (root mean square fluctuation), Rg (radius of gyration), and SASA (solvent accessible surface area) were within the acceptable limits. Free energy calculations using Prime-MM/GBSA suggest that Celecoxib formed the most stable complex with TACE, followed by Glipizide, Sitagliptin, and Lapatinib. The finding of this study suggests a mechanism for drugs to aggravate SARS-CoV-2 infection and hence high mortality in patients suffering from chronic diseases. Communicated by Ramaswamy H. Sarma

Structural and Functional Aspects of Ebola Virus Proteins.

Ebola virus (EBOV), member of genus Ebolavirus, family Filoviridae, have a non-segmented, single-stranded RNA that contains seven genes: (a) nucleoprotein (NP), (b) viral protein 35 (VP35), (c) VP40, (d) glycoprotein (GP), (e) VP30, (f) VP24, and (g) RNA polymerase (L). All genes encode for one protein each except GP, producing three pre-proteins due to the transcriptional editing. These pre-proteins are translated into four products, namely: (a) soluble secreted glycoprotein (sGP), (b) Δ-peptide, (c) full-length transmembrane spike glycoprotein (GP), and (d) soluble small secreted glycoprotein (ssGP). Further, shed GP is released from infected cells due to cleavage of GP by tumor necrosis factor α-converting enzyme (TACE). This review presents a detailed discussion on various functional aspects of all EBOV proteins and their residues. An introduction to ebolaviruses and their life cycle is also provided for clarity of the available analysis. We believe that this review will help understand the roles played by different EBOV proteins in the pathogenesis of the disease. It will help in targeting significant protein residues for therapeutic and multi-protein/peptide vaccine development.

Tumor necrosis factor receptor-1 is selectively sequestered into Schwann cell extracellular vesicles where it functions as a TNFα decoy.

Schwann cells (SCs) are known to produce extracellular vesicles (EV) that participate in cell-cell communication by transferring cargo to target cells, including mRNAs, microRNAs, and biologically active proteins. Herein, we report a novel mechanism whereby SC EVs may regulate PNS physiology, especially in injury, by controlling the activity of TNFα. SCs actively sequester tumor necrosis factor receptor-1 (TNFR1) into EVs at high density, accounting for about 2% of the total protein in SC EVs (~1000 copies TNFR1/EV). Although TNFR2 was robustly expressed by SCs in culture, TNFR2 was excluded from SC EVs. SC EV TNFR1 bound TNFα, decreasing the concentration of free TNFα available to bind to cells and thus served as a TNFα decoy. SC EV TNFR1 significantly inhibited TNFα-induced p38 MAPK phosphorylation in cultured SCs. When TNFR1 was proteolytically removed from SC EVs using tumor necrosis factor-α converting enzyme (TACE) or neutralized with antibody, the ability of TNFα to activate p38 MAPK in the presence of these EVs was restored. As further evidence of its decoy activity, SC EV TNFR1 modified TNFα activities in vitro including: (1) regulation of expression of other cytokines; (2) effects on SC morphology; and (3) effects on SC viability. SC EVs also modified the effects of TNFα on sciatic nerve morphology and neuropathic pain-related behavior in vivo. By sequestering TNFR1 in EVs, SCs may buffer against the potentially toxic effects of TNFα. SC EVs provide a novel mechanism for the spatial and temporal regulation of neuro-inflammation.

Combined Detection of Plasma Tumor Necrosis Factor-α Converting Enzyme and Notch1 is Valuable in Screening Endoleak After Endovascular Abdominal Aortic Aneurysms Repair

Endoleaks may be present in up to 25% of patients after endovascular abdominal aortic aneurysm repair (EVAR) and there is no clear consensus on valuable biomarkers to determine endoleak presence. The aim of this study was to examine the potential value of plasma tumor necrosis factor-α converting enzyme (TACE) and Notch1 concentrations in determining endoleak presence after EVAR. A total of 110 patients with abdominal aortic aneurysm (AAA) who underwent EVAR were enrolled in our study, and plasma TACE and Notch1 concentrations were measured prior to and 6 months after EVAR. Logistic regression was performed to assess the association of postoperative plasma TACE and Notch1 concentrations with endoleak after adjusting for potential confounders. The ability of plasma TACE and Notch1 concentrations to determine endoleak presence was assessed using receiver operating characteristic (ROC) curves and area under the curve (AUC). Twenty-four patients developed endoleaks 6 months after EVAR. Both postoperative plasma TACE and Notch1 concentrations were higher in patients with endoleak than in those without endoleak (2376.4 ± 28.1 pg/ml vs. 2094.1 ± 27.3 pg/ml, P < 0.01; 218.6 ± 1.9 pg/ml vs. 195.0 ± 2.1 pg/ml, P < 0.01, respectively). The AUCs from ROC curve analysis of plasma TACE and Notch1 concentrations in determining endoleak presence were 0.844 (95% CI 0.771 to 0.918, P < 0.01) and 0.860 (95% CI 0.791 to 0.930, P < 0.01), respectively. Combining the detection of plasma Notch1 and TACE concentrations could improve the accuracy in determining endoleak presence (AUC 0.930, 95% CI 0.883 to 0.978, P < 0.01). The predicted probability cutoff of 0.22 yielded a sensitivity of 95.8% and a specificity of 82.6% for endoleak presence. Plasma TACE and Notch1 levels can discriminate patients with and without endoleak 6 months after EVAR, and have a potential role in screening patients requiring computed tomography angiography.

Potential Detrimental Role of Soluble ACE2 in Severe COVID-19 Comorbid Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) takes its entry to host cell via angiotensin converting enzyme 2 (ACE2) receptor. Biochemical and structural analysis indicate the roles of other important proteins and/or enzymes involved in this process including disintegrin and metalloproteinase domain-containing protein 17 (ADAM17) also known as tumor necrosis factor-α-converting enzyme (TACE) and trans membrane serine protease 2 (TMPRSS2). As a biological protective mechanism ACE2 converts angiotensin II (Ang II) to angiotensin (1-7) and helps to balance renin angiotensin system (RAS). Being the key receptor for virus spike binding and subsequent role in viral entry, the detrimental effect of ACE2 is also of great concern. Membrane-bound ACE2 ectodomain is shedded by ADAM17 upon viral spike binding, Ang II overproduction and in some disease condition. The shedded soluble ACE2 (sACE2) retains its catalytic activity, but its exact role in viral entry and pathogenesis is still unclear. It has been claimed that therapeutic sACE2 which mimic the ectodomain can exert dual effects; reduction of excess Ang II and blocking the viral entry by masking spike protein. But the important concern is why SARS-CoV-2 comorbid patients having higher amount of sACE2 cannot attain such benefit in viral infection. At this context, in this perspective we partially argue about the protective role of sACE2 and hypothesize that sACE2 can convert Ang II but we additionally speculate a series of events where protease primed or non-primed virus-sACE2 complex can possibly take entry inside the host cell. As floating virus can bind a good number of sACE2, upon endocytosis by host cell, extracellular sACE2 level could be reduced drastically. As a consequence, rapid rise in Ang II level can potentially aggravate disease severity through Ang II-angiotensin receptor 1 (AT1R) axis in comorbid patients. Thus, therapeutic recombinant sACE2 should be designed accordingly to achieve maximum outcome in treating COVID-19.

The Blockade of TACE-Dependent EGF Receptor Activation by Losartan-Erlotinib Combination Attenuates Renal Fibrosis Formation in 5/6-Nephrectomized Rats Under Vitamin D Deficiency.

Chronic kidney disease (CKD) has been considered a major public health issue. In addition to cardiovascular diseases and infections, hypovitaminosis D has been considered a non-traditional aggravating factor for CKD progression. Interstitial fibrosis is a hallmark of CKD strongly correlated with deterioration of renal function. Transforming growth factor β (TGF-β) is the major regulatory profibrotic cytokine in CKD. Many injurious stimuli converge on the TGF-β pathway, which has context-dependent pleiotropic effects and interacts with several related renal fibrosis formation (RFF) pathways. Epidermal growth factor receptor (EGFR) is critically involved in CKD progression, exerting a pathogenic role in RFF associated with TGF-β-related fibrogenesis. Among others, EGFR pathway can be activated by a disintegrin and a metalloproteinase known as tumor necrosis factor α-converting enzyme (TACE). Currently no effective therapy is available to completely arrest RFF and slow the progression of CKD. Therefore, we investigated the effects of a double treatment with losartan potassium (L), an AT1R antagonist, and the tyrosine kinase inhibitor erlotinib (E) on the alternative pathway of RFF related to TACE-dependent EGFR activation in 5/6-nephrectomized rats under vitamin D deficiency (D). During the 90-day protocol, male Wistar rats under D, were submitted to 5/6 nephrectomy (N) on day 30 and randomized into four groups: N+D, no treatment; N+D+L, received losartan (50 mg/kg/day); N+D+E, received erlotinib (6 mg/kg/day); N+D+L+E received losartan+erlotinib treatment. N+D+L+E data demonstrated that the double treatment with losartan+erlotinib not only blocked the TACE-dependent EGF receptor activation but also prevented the expression of TGF-β, protecting against RFF. This renoprotection by losartan+erlotinib was corroborated by a lower expression of ECM proteins and markers of phenotypic alteration as well as a lesser inflammatory cell infiltrate. Although erlotinib alone has been emerging as a renoprotective drug, its association with losartan should be considered as a potential therapeutic strategy on the modulation of RFF.

Angiotensin-converting Enzyme 2–containing Small Extracellular Vesicles and Exomeres Bind the Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein

Angiotensin-converting Enzyme 2–containing Small Extracellular Vesicles and Exomeres Bind the Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein

A JUN N-terminal kinase inhibitor induces ectodomain shedding of the cancer-associated membrane protease Prss14/epithin via protein kinase CβII

Serine protease 14 (Prss14)/epithin is a transmembrane serine protease that plays essential roles in tumor progression and metastasis and therefore is a promising target for managing cancer. Prss14/epithin shedding may underlie its activity in cancer and worsen outcomes; accordingly, a detailed understanding of the molecular mechanisms in Prss14/epithin shedding may inform the design of future cancer therapies. On the basis of our previous observation that an activator of PKC, phorbol 12-myristate 13-acetate (PMA), induces Prss14/epithin shedding, here we further investigated the intracellular signaling pathway involved in this process. While using mitogen-activated protein kinase inhibitors to investigate possible effectors of downstream PKC signaling, we unexpectedly found that an inhibitor of c-Jun N-terminal kinase (JNK), SP600125, induces Prss14/epithin shedding even in the absence of PMA. SP600125-induced shedding, like that stimulated by PMA, was mediated by tumor necrosis factor-α–converting enzyme. In contrast, a JNK activator, anisomycin, partially abolished the effects of SP600125 on Prss14/epithin shedding. Moreover, the results from loss-of-function experiments with specific inhibitors, short hairpin RNA–mediated knockdown, and overexpression of dominant-negative PKCβII variants indicated that PKCβII is a major player in JNK inhibition– and PMA-mediated Prss14/epithin shedding. SP600125 increased phosphorylation of PKCβII and tumor necrosis factor-α–converting enzyme and induced their translocation into the plasma membrane. Finally, in vitro cell invasion experiments and bioinformatics analysis of data in The Cancer Genome Atlas breast cancer database revealed that JNK and PKCβII are important for Prss14/epithin-mediated cancer progression. These results provide important information regarding strategies against tumor metastasis.

Effects of Central Intervention of Tumor Necrosis Factor‐α Converting Enzyme (TACE) on Neuroinflammation and Cardiac Function in Heart Failure

Central nervous system inflammation has been implicated in the neurohumoral activation and disease progression in experimental animal models of heart failure (HF). The pro‐inflammatory cytokine tumor necrosis factor‐α (TNF‐α) increases in cardiovascular/autonomic brain regions including the paraventricular nucleus of the hypothalamus (PVN) and subfornical organ (SFO), and contributes significantly to the augmented sympathetic nerve activity in HF. TNF‐α is initially synthesized as a membrane bound protein that is proteolytically cleaved by TNF‐α converting enzyme (TACE), also known as a disintegrin and metalloprotease 17 (ADAM17), to become the fully functional inflammatory mediator. Our previous study demonstrated that TACE has elevated expression in the PVN and SFO and mediates TNF‐α‐induced sympathetic excitation and hemodynamic responses in HF rats. However, whether inhibition of TACE in the brain has a protective effect on central inflammation and cardiac function in HF remains unclear. We hypothesized that inhibition of TACE activity in the brain reduces central inflammation and improves left ventricular (LV) function during HF. Adult male Sprague‐Dawley rats were studied 4–5 weeks after induction of HF by coronary artery ligation. TACE activity was chronically inhibited specifically in the brain by infusion of the TACE inhibitor TAPI‐1 (30μg/day) via an osmotic minipump connected to an intracerebroventricular (ICV) cannula. Treatment with TAPI‐1 or vehicle began immediately following the myocardial infarction. At the end of experiments, LV function was assessed by echocardiography and tissues were collected for molecular analysis. In HF rats‐treated with TAPI‐1, the LV ejection fraction (26.8±0.9% vs 34.8±6.4%) was improved, although this did not reach statistical significance vs. HF treated with vehicle. Wet lung weight to body weight ratio also showed a trend towards being improved in TAPI‐1 treated animals (6.3±0.3mg/g vs. 4.8±0.4mg/g, vehicle vs. TAPI‐1, p=0.32). Additionally, TAPI‐1 treatment significantly decreased mRNA levels of proinflammatory mediators including TNF‐α, IL‐1β, and TACE in the SFO (TNF‐α: 0.28±0.10, p&lt;0.05; IL1‐β: 0.25±0.11, p&gt;0.05; TACE: 0.68±0.14, p&lt;0.05, fold change vs. vehicle) and resulted in a trend toward reduced levels of these measurements in the PVN (TNF‐α: 0.52±0.13, p=0.24; IL1‐β: 0.58±0.11, p=0.21; TACE: 0.87±0.11, p=0.43, fold change vs. vehicle). TNF‐α expression was also reduced in both the superior cervical (0.35±0.07, p&lt;0.05, fold change vs. vehicle) and stellate ganglia (0.44±0.14, p&lt;0.05 fold change vs. vehicle). Taken together, these data suggest that central inhibition of TACE activity diminishes the inflammatory state in the brain and improve cardiac function in HF.

Regulation of iRhom-2/Tumor Necrosis Factor-α Converting Enzyme Pathway and Oxidative Stress Protects the Renal Injury with Anemonin in Streptozotocin-Induced Diabetic Nephropathy Neonatal Rat Model

Diabetic nephropathy (DN) is a chronic complication of diabetes, and thus the present investigation evaluates the nephroprotective effect of anemonin against streptozotocin (STZ)-induced DN rats. Diabetes was induced by intraperitoneal administration of STZ (50 mg/kg) on day 2 and 3 postnatal, and rats were kept as such for the duration of 12 weeks. Thereafter, rats were treated with anemonin 75 and 150 mg/kg per oral for the period 4 week which means between the period of 12–16 weeks. Effect of anemonin was estimated by determining the blood glucose, markers of nephropathy, and mediators of inflammation in the serum and activity of tumor necrosis factor-α (TNF-α)converting enzyme (TACE) in the kidney tissue of DN rats. Moreover, reverse transcriptase polymerase chain reaction and western blot assay were determined in the kidney tissue homogenate of DN rats. Histopathology study was done by Periodic acid-Schiff’s and masson staining for the pathological changes and apoptosis of podocytes in the kidney tissue of DN rats. Moreover, production of reactive oxygen species (ROS) was estimated in the kidney tissue by 2’,7’-dichlorofluorescein staining. Data of study reveal that anemonin significantly reduces (p < 0.01) the blood glucose and markers of renal injury in the serum and urine of DN rats. There was a reduction in the level of cytokines in the serum, and production of ROS and activity of TACE were reduced in the kidney tissue of the anemonin-treated group than in the DN group. Expression of iRhom-2, TACE, TNF-α, and inducible nitric oxide synthase protein and histopathology of kidney tissue were attenuated in the anemonin-treated group in DN rats. In conclusion, data of study reveal that treatment with anemonin ameliorates progression of renal injury by regulating TACE/iRhom-2 signaling pathway.

Genetic Association Between NGFR, ADAM17 Gene Polymorphism, and Parkinson's Disease in the Chinese Han Population.

Parkinson's disease (PD) is a common neurodegenerative disease characterized by neuronal loss in the substantia nigra. The p75 neurotrophin receptor (p75NTR, encoded by NGFR) was found to play an important role in the selective neuronal death of dopamine neurons in the substantia nigra, as well as the pathogenesis and development of PD. To assess the association between NGFR gene polymorphism and the susceptibility of PD, this case-control study consisting of 414 PD patients and 623 age- and sex-matched controls in a Chinese Han cohort was conducted. Twelve tag-single nucleotide polymorphisms (tag-SNPs) were selected from the NGFR gene through the construction of linkage disequilibrium blocks. One tag-SNP from the ADAM17 gene was also selected owing to its function of encoding tumor necrosis factor α-converting enzyme, which is responsible for the shedding of the extracellular domain of p75NTR. A multiplex polymerase chain reaction-ligase detection reaction (PCR-LDR) method was applied for genotyping. The associations between tag-SNPs and the risk of PD with the adjustment for age and sex were analyzed by unconditional logistic regression, and five genetic models including codominant, dominant, recessive, over-dominant, and additive models were applied. The results showed that among the 13 tag-SNPs, rs741073 was associated with a reduced risk of PD in the codominant (OR = 0.71, 95% CI = 0.54-0.93, P = 0.037), dominant (OR = 0.76, 95% CI = 0.58-0.98, P = 0.033), and over-dominant models (OR = 0.71, 95% CI = 0.54-0.92, P = 0.010), and rs1804011 was also associated with a reduced risk of PD in the codominant (OR = 0.69, 95% CI = 0.50-0.95, P = 0.049), dominant (OR = 0.69, 95% CI = 0.50-0.93, P = 0.014), over-dominant (OR = 0.70, 95% CI = 0.51-0.96, P = 0.025), and additive models (OR = 0.72, 95% CI = 0.54-0.94, P = 0.016). However, these associations did not retain after Bonferroni correction. Conclusively, our study failed to reveal the association between the selected tag-SNPs within NGFR, ADAM17, and the susceptibility of PD. The role of p75NTR and its gene polymorphisms in the pathogenesis of PD needs to be further studied.

Metalloproteinases TACE and MMP-9 Differentially Regulate Death Factors on Adult and Neonatal Monocytes After Infection with Escherichia coli.

Background: Cleaving ligands and receptors of the tumor necrosis factor (TNF) superfamily can critically regulate the induction of apoptosis. Matrix metalloproteinases (MMPs) such as MMP-9 and tumor necrosis factor-α-converting enzyme (TACE) have been shown to cleave CD95-Ligand (CD95L) and TNF/(TNF receptor-1) TNFR1 which induce phagocytosis induced cell death (PICD) in adult monocytes. This process is reduced in neonatal monocytes. Methods: Here we tested in vitro, whether Escherichia coli infection mounts for activation of MMP-9 and TACE in monocytes and whether this process regulates PICD. Results: The surface expression of TACE was most prominent on infected adult monocytes. In contrast, surface presentation of MMP-9 was highest on infected neonatal monocytes. Selective blocking of MMP-9 decreased CD95L secretion, while inhibition of TACE left CD95L secretion unaltered. Blocking of MMP-9 increased surface CD95L (memCD95L) expression on infected neonatal monocytes to levels comparable to infected adult monocytes. Moreover, MMP-9 inhibition raised PICD of infected neonatal monocytes to levels observed for infected adult monocytes. In contrast, TACE inhibition decreased PICD in infected monocytes. Addition of extracellular TNF effectively induced memCD95L presentation and PICD of adult monocytes and less of neonatal monocytes. Conclusion: MMP-9 activity is crucial for downregulating cell-contact dependent PICD in E. coli infected neonatal monocytes. By this mechanism, MMP-9 could contribute to reducing sustained inflammation in neonates.

Tyrosine phosphorylation directs TACE into extracellular vesicles via unconventional secretion.

When studying how HIV-1 Nef can promote packaging of the proinflammatory transmembrane protease TACE (tumor necrosis factor-α converting enzyme) into extracellular vesicles (EVs) we have revealed a novel tyrosine kinase-regulated unconventional protein secretion (UPS) pathway for TACE. When TACE was expressed without its trafficking cofactor iRhom allosteric Hck activation by Nef triggered translocation of TACE into EVs. This process was insensitive to blocking of classical secretion by inhibiting endoplasmic reticulum (ER) to Golgi transport, and involved a distinct form of TACE devoid of normal glycosylation and incompletely processed for prodomain removal. Like most other examples of UPS this process was Golgi reassembly stacking protein (GRASP)-dependent but was not associated with ER stress. These data indicate that Hck-activated UPS provides an alternative pathway for TACE secretion that can bypass iRhom-dependent ER to Golgi transfer, and suggest that tyrosine phosphorylation might have a more general role in regulating UPS.

Fisetin attenuates high fat diet-triggered hepatic lipid accumulation: A mechanism involving liver inflammation overload associated TACE/TNF-α pathway

Excess fat-rich diet ingestion predisposes the liver to non-alcoholic fatty liver disease (NAFLD), but the mechanism is complicated. Fisetin (Fn) as a natural flavonoid with many bio-activities was determined in a number of diseases models. TACE (tumor necrosis factor-α-converting enzyme)-combined tumor necrosis factor-α (TACE/TNF-α) signaling played a significant role in inflammation-associated diseases. The study aimed to explore the protective mechanisms of Fn against high fat diet (HFD)-induced nonalcoholic steatohepatitis (NASH), with particular focus on TACE/TNF-α signaling. HFD-fed C57BL/6 mice were used as the metabolic syndrome model to explore the effects of Fn on NASH and to determine whether TACE/TNF-α activation was involved in the process. Indeed, HFD increases systemic metabolic disorder, promotes circulating levels of pro-inflammatory cytokines produce, aggravates development of hepatic inflammation, resulting in inflammation overload-associated excessive activation of TACE/TNF-α, ultimately induces hepatic lipid accumulation and NASH. Fisetin protected against HFD-induced liver inflammation and lipid accumulation by decreasing metabolic disorder and inflammation overload-related TACE/TNF-α activation, inhibiting over-expression of pro-inflammatory cytokines, negatively regulating HFD-triggered abnormal lipid metabolism-related genes expression, finally restricting lipid deposition and hepatic steatosis. Fisetin suppressed HFD-induced liver inflammation and lipid accumulation by decreasing metabolic disorder and hepatic inflammation overload-related TACE/TNF-α activation.

Translocation and activation of sphingosine kinase 1 by ceramide-1-phosphate.

Sphingosine kinases (SphKs) and ceramide kinase (CerK) phosphorylate sphingosine to sphingosine-1-phosphate (S1P) and ceramide to ceramide-1-phosphate (C1P), respectively. S1P and C1P are bioactive lipids that regulate cell fate/function and human health/diseases. The translocation and activity of SphK1 are regulated by its phosphorylation of Ser 225 and by anionic lipids such as phosphatidic acid and phosphatidylserine. However, the roles of another anionic lipid C1P on SphK1 functions have not yet been elucidated, thus, we here investigated the regulation of SphK1 by CerK/C1P. C1P concentration dependently bound with and activated recombinant human SphK1. The inhibition of CerK reduced the phorbol 12-myristate 13-acetate-induced translocation of SphK1 to the plasma membrane (PM) and activation of the enzyme in membrane fractions of cells. A treatment with C1P translocated wild-type SphK1, but not the SphK1-S225A mutant, to the PM without affecting phosphorylation signaling. A cationic RxRH sequence is proposed to be a C1P-binding motif in α-type cytosolic phospholipase A 2 and tumor necrosis factor α-converting enzyme. The mutation of four cationic amino acids to Ala in the 56-RRNHAR-61 domain in SphK1 reduced the phorbol 12-myristate 13-acetate- and C1P-induced translocation of SphK1 to the PM, however, the capacity of C1P to bind with and activate SphK1 was not affected by this mutation. In conclusion, C1P modulates SphK1 functions by interacting with multiple sites in SphK1.