Proprotein convertase furin in SARS-CoV-2 and non-small cell lung cancer.
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ABSTRACT:
SUBMITTER: Rosell R
PROVIDER: S-EPMC7481648 | biostudies-literature | 2020 Aug
REPOSITORIES: biostudies-literature
Publications
Proprotein convertase furin in SARS-CoV-2 and non-small cell lung cancer.
Rosell Rafael R Karachaliou Niki N Fancelli Sara S Arrieta Oscar O Troncone Giancarlo G Cao Peng P
Translational lung cancer research 20200801 4
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Project description:The proprotein convertase enzyme FURIN processes immature pro-proteins into functional end- products. FURIN is upregulated in activated immune cells and it regulates T-cell dependent peripheral tolerance and the Th1/Th2 balance. FURIN also promotes the infectivity of pathogens by activating bacterial toxins and by processing viral proteins. Here, we evaluated the role of FURIN in LysM+ myeloid cells in vivo. Mice with a conditional deletion of FURIN in their myeloid cells (LysMCre-fur(fl/fl)) were healthy and showed unchanged proportions of neutrophils and macrophages. Instead, LysMCre-fur(fl/fl) mice had elevated serum IL-1β levels and reduced numbers of splenocytes. An LPS injection resulted in accelerated mortality, elevated serum pro-inflammatory cytokines and upregulated numbers of pro-inflammatory macrophages. A genome-wide gene expression analysis revealed the overexpression of several pro-inflammatory genes in resting FURIN-deficient macrophages. Moreover, FURIN inhibited Nos2 and promoted the expression of Arg1, which implies that FURIN regulates the M1/M2-type macrophage balance. FURIN was required for the normal production of the bioactive TGF-β1 cytokine, but it inhibited the maturation of the inflammation-provoking TACE and Caspase-1 enzymes. In conclusion, FURIN has an anti-inflammatory function in LysM+ myeloid cells in vivo.
| S-EPMC5342350 | biostudies-literature
Project description:The proprotein convertase enzyme FURIN processes immature pro-proteins into functional end- products. FURIN is upregulated in activated immune cells and it regulates T-cell dependent peripheral tolerance and the Th1/Th2 balance. FURIN also promotes the infectivity of pathogens by activating bacterial toxins and by processing viral proteins. Here, we evaluated the role of FURIN in LysM+ myeloid cells in vivo. Mice with a conditional deletion of FURIN in their myeloid cells (LysMCre-fur(fl/fl)) were healthy and showed unchanged proportions of neutrophils and macrophages. Instead, LysMCre-fur(fl/fl) mice had elevated serum IL-1β levels and reduced numbers of splenocytes. An LPS injection resulted in accelerated mortality, elevated serum pro-inflammatory cytokines and upregulated numbers of pro-inflammatory macrophages. A genome-wide gene expression analysis revealed the overexpression of several pro-inflammatory genes in resting FURIN-deficient macrophages. Moreover, FURIN inhibited Nos2 and promoted the expression of Arg1, which implies that FURIN regulates the M1/M2-type macrophage balance. FURIN was required for the normal production of the bioactive TGF-β1 cytokine, but it inhibited the maturation of the inflammation-provoking TACE and Caspase-1 enzymes. In conclusion, FURIN has an anti-inflammatory function in LysM+ myeloid cells in vivo.
2016-12-30 | GSE84117 | GEO
Project description:Proprotein convertases (PCSK) have a critical role in the body homeostasis as enzymes responsible for processing precursor proteins into their mature forms. FURIN, the first characterized member of the mammalian PCSK family, is overexpressed in multiple malignancies and the inhibition of its activity has been considered potential cancer treatment. FURIN has also an important function in the adaptive immunity, since its deficiency in T cells causes an impaired peripheral immune tolerance and accelerates immune responses. We addressed whether deleting FURIN from the immune cells would strengthen anticancer responses by subjecting mouse strains lacking FURIN from either T cells or macrophages and granulocytes to the DMBA/TPA two-stage skin carcinogenesis protocol. Unexpectedly, deficiency of FURIN in T cells resulted in enhanced and accelerated development of tumors, whereas FURIN deletion in macrophages and granulocytes had no effect. The epidermises of T-cell-specific FURIN deficient mice were significantly thicker with more proliferating Ki67+ cells. In contrast, there were no differences in the numbers of the T cells. The flow cytometric analyses of T-cell populations in skin draining lymph nodes showed that FURIN T-cell KO mice have an inherent upregulation of early activation marker CD69 as well as more CD4+CD25+Foxp3+ positive T regulatory cells. In the early phase of tumor promotion, T cells from the T-cell-specific FURIN knockout animals produced more interferon gamma, whereas at later stage the production of Th2- and Th17-type cytokines was more prominent than in wild-type controls. In conclusion, while PCSK inhibitors are promising therapeutics in cancer treatment, our results show that inhibiting FURIN specifically in T cells may promote squamous skin cancer development.
| S-EPMC5214164 | biostudies-literature
Project description:Osteocalcin (OCN) is an osteoblast-derived hormone that increases energy expenditure, insulin sensitivity, insulin secretion, and glucose tolerance. The cDNA sequence of OCN predicts that, like many other peptide hormones, OCN is first synthesized as a prohormone (pro-OCN). The importance of pro-OCN maturation in regulating OCN and the identity of the endopeptidase responsible for pro-OCN cleavage in osteoblasts are still unknown. Here, we show that the proprotein convertase furin is responsible for pro-OCN maturation in vitro and in vivo. Using pharmacological and genetic experiments, we also determined that furin-mediated pro-OCN cleavage occurred independently of its γ-carboxylation, a posttranslational modification that is known to hamper OCN endocrine action. However, because pro-OCN is not efficiently decarboxylated and activated during bone resorption, inactivation of furin in osteoblasts in mice resulted in decreased circulating levels of undercarboxylated OCN, impaired glucose tolerance, and reduced energy expenditure. Furthermore, we show that Furin deletion in osteoblasts reduced appetite, a function not modulated by OCN, thus suggesting that osteoblasts may secrete additional hormones that regulate different aspects of energy metabolism. Accordingly, the metabolic defects of the mice lacking furin in osteoblasts became more apparent under pair-feeding conditions. These findings identify furin as an important regulator of bone endocrine function.
| S-EPMC5663350 | biostudies-literature
Project description:The multinucleated syncytial trophoblast, which forms the outermost layer of the placenta and serves multiple functions, is differentiated from and maintained by cytotrophoblast cell fusion. Deficiencies in syncytial trophoblast differentiation or maintenance likely contribute to intrauterine growth restriction and pre-eclampsia, two common gestational diseases. The cellular and molecular mechanisms governing trophoblast syncytialization are poorly understood. We report here that the proprotein convertase furin is highly expressed in syncytial trophoblast in the first trimester human placentas, and expression of furin in the syncytiotrophoblast is significantly lower in the placentas from pre-eclamptic patients as compared with their gestational age-matched control placentas. Using multiple experimental models including induced fusion of choriocarcinoma BeWo cells and spontaneous fusion of primary cultured cytotrophoblast cells or placental explants, we demonstrate that cytotrophoblast cell fusion and syncytialization are accompanied by furin expression. Furin-specific siRNAs or inhibitors inhibit cell fusion in BeWo cells, as well as trophoblast syncytialization in human placental explants. Furthermore, type 1 IGF receptor (IGF1R) is indicated in this study as a substrate of furin, and processing of IGF1R by furin is an essential mechanism for syncytialization. Finally, using lentivirus-mediated RNAi targeting to mouse trophectoderm, we demonstrate that furin function is required for the development of syncytiotrophoblast structure in the labyrinth layer, as well as for normal embryonic development.
| S-EPMC3641329 | biostudies-literature
Project description:The pro-protein convertase furin is a highly specific serine protease involved in the proteolytic maturation of many proteins in the secretory pathway. It also activates surface proteins of many viruses including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Furin inhibitors effectively suppress viral replication and thus are promising antiviral therapeutics with broad application potential. Polybasic substrate-like ligands typically trigger conformational changes shifting furin's active site cleft from the OFF-state to the ON-state. Here, we solved the X-ray structures of furin in complex with four different arginine mimetic compounds with reduced basicity. These guanylhydrazone-based inhibitor complexes showed for the first time an active site-directed binding mode to furin's OFF-state conformation. The compounds undergo unique interactions within the S1 pocket, largely different compared to substrate-like ligands. A second binding site was identified at the S4/S5 pocket of furin. Crystallography-based titration experiments confirmed the S1 site as the primary binding pocket. We also tested the proprotein convertases PC5/6 and PC7 for inhibition by guanylhydrazones and found an up to 7-fold lower potency for PC7. Interestingly, the observed differences in the Ki values correlated with the sequence conservation of the PCs at the allosteric sodium binding site. Therefore, OFF-state-specific targeting of furin can serve as a valuable strategy for structure-based development of PC-selective small-molecule inhibitors.
| S-EPMC8453481 | biostudies-literature
Project description:Novel elongated and shortened derivatives of the peptidomimetic furin inhibitor phenylacetyl-Arg-Val-Arg-4-amidinobenzylamide were synthesized. The most potent compounds, such as Nα (carbamidoyl)Arg-Arg-Val-Arg-4-amidinobenzylamide (Ki =6.2 pm), contain additional basic residues at the N terminus and inhibit furin in the low-picomolar range. Furthermore, to decrease the molecular weight of this inhibitor type, compounds that lack the P5 moiety were prepared. The best inhibitors of this series, 5-(guanidino)valeroyl-Val-Arg-4-amidinobenzylamide and its P3 tert-leucine analogue displayed Ki values of 2.50 and 1.26 nm, respectively. Selected inhibitors, together with our previously described 4-amidinobenzylamide derivatives as references, were tested in cell culture for their activity against furin-dependent infectious pathogens. The propagation of the alphaviruses Semliki Forest virus and chikungunya virus was strongly inhibited in the presence of selected derivatives. Moreover, a significant protective effect of the inhibitors against diphtheria toxin was observed. These results confirm that the inhibition of furin should be a promising approach for the short-term treatment of acute infectious diseases.
| S-EPMC5572662 | biostudies-literature
Project description:Furin is one of seven proprotein convertase family members that promote proteolytic maturation of proproteins. It is induced in activated T cells and is reported to process a variety of substrates including the anti-inflammatory cytokine transforming growth factor (TGF)-beta1 (refs 2-4), but the non-redundant functions of furin versus other proprotein convertases in T cells are unclear. Here we show that conditional deletion of furin in T cells allowed for normal T-cell development but impaired the function of regulatory and effector T cells, which produced less TGF-beta1. Furin-deficient T regulatory (Treg) cells were less protective in a T-cell transfer colitis model and failed to induce Foxp3 in normal T cells. Additionally, furin-deficient effector cells were inherently over-active and were resistant to suppressive activity of wild-type Treg cells. Thus, our results indicate that furin is indispensable in maintaining peripheral tolerance, which is due, at least in part, to its non-redundant, essential function in regulating TGF-beta1 production. Targeting furin has emerged as a strategy in malignant and infectious disease. Our results suggest that inhibiting furin might activate immune responses, but may result in a breakdown in peripheral tolerance.
| S-EPMC2758057 | biostudies-literature
Project description:Furin is a proprotein convertase induced in activated T cells, reported to processes the anti-inflammatory cytokine TGFb-1. Herein, we show that conditional deletion of furin in T cells allowed for normal T cell development but impaired the function of regulatory T cells and effector cells, which produced less TGFb-1. Furin-deficient Treg cells, were less protective in a T cell transfer colitis model and failed to induce Foxp3 in normal T cells. Furin-deficient effector cells were inherently overly active and were resistant to suppressive activity of wild-type Tregs. Thus, our results indicate that furin is indispensable in maintaining peripheral tolerance, which is due, at least in part, to its nonredundant, essential function in regulating TGFb-1 production. Targeting furin has emerged as a strategy in malignant and infectious disease. The current work suggests that inhibiting furin might activate immune responses, but may result in a breakdown in peripheral tolerance.
2008-06-26 | GSE11884 | GEO
Project description:In the present study, we have investigated processing and maturation of the envelope glycoprotein (GP) of Ebola virus. When GP expressed from vaccinia virus vectors was analyzed by pulse-chase experiments, the mature form and two different precursors were identified. First, the endoplasmic reticulum form preGPer, full-length GP with oligomannosidic N-glycans, was detected. preGPer (110 kDa) was replaced by the Golgi-specific form preGP (160 kDa), full-length GP containing mature carbohydrates. preGP was finally converted by proteolysis into mature GP1,2, which consisted of two disulfide-linked cleavage products, the amino-terminal 140-kDa fragment GP1, and the carboxyl-terminal 26-kDa fragment GP2. GP1,2 was also identified in Ebola virions. Studies employing site-directed mutagenesis revealed that GP was cleaved at a multibasic amino acid motif located at positions 497 to 501 of the ORF. Cleavage was blocked by a peptidyl chloromethylketone containing such a motif. GP is cleaved by the proprotein convertase furin. This was indicated by the observation that cleavage did not occur when GP was expressed in furin-defective LoVo cells but that it was restored in these cells by vector-expressed furin. The Reston subtype, which differs from all other Ebola viruses by its low human pathogenicity, has a reduced cleavability due to a mutation at the cleavage site. As a result of these observations, it should now be considered that proteolytic processing of GP may be an important determinant for the pathogenicity of Ebola virus.
| S-EPMC20453 | biostudies-literature