RESUMO
The PD-1/PD-L1 pathway is a key immune checkpoint that regulates T cell activation. There is strong rationale to develop PD-1 agonists as therapeutics against autoimmunity, but progress in this area has been limited. Here, we generated T cell receptor (TCR) targeting, PD-1 agonist bispecifics called ImmTAAI molecules that mimic the ability of PD-L1 to facilitate the colocalization of PD-1 with the TCR complex at the target cell-T cell interface. PD-1 agonist ImmTAAI molecules specifically bound to target cells and were highly effective in activating the PD-1 receptor on interacting T cells to achieve immune suppression. Potent PD-1 antibody ImmTAAI molecules closely mimicked the mechanism of action of endogenously expressed PD-L1 in their localization to the target cell-T cell interface, inhibition of proximal TCR signaling events, and suppression of T cell function. At picomolar concentrations, these bispecifics suppressed cytokine production and inhibited CD8+ T cell-mediated cytotoxicity in vitro. Crucially, in soluble form, the PD-1 ImmTAAI molecules were inactive and, hence, could avoid systemic immunosuppression. This study outlines a promising new route to generate more effective, potent, tissue-targeted PD-1 agonists that can inhibit T cell function locally with the potential to treat autoimmune and chronic inflammatory diseases of high unmet need.
Assuntos
Inibidores de Checkpoint Imunológico/uso terapêutico , Imunoterapia/métodos , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Antígenos de Linfócitos T/antagonistas & inibidores , HumanosRESUMO
Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) is considered to be a promising antitumor drug because of its selective proapoptotic properties on tumor cells. However, the clinical application of TRAIL is until now limited because of the resistance of several cancer cells, which can occur at various levels in the TRAIL signaling pathway. The role of decoy receptors that can side-track TRAIL, thereby preventing the formation of an activated death receptor, has been extensively studied. In this study, we have focused on extracellular vesicles (EVs) that are known to play a role in cell-to-cell communication and that can be released by donor cells into the medium transferring their components to recipient cells. TRAIL-induced apoptotic signaling is triggered upon the binding of two death receptors, DR4 and DR5. Here, we found that DR5 but not DR4 is present in the conditioned medium (CM)-derived from various cancer cells. Moreover, we observed that DR5 was exposed on EVs and can act as "decoy receptor" for binding to TRAIL. This results in a strongly reduced number of apoptotic cells upon treatment with DR5-specific TRAIL variant DHER in CM. This reduction happened with EVs containing either the long or short isoform of DR5. Taken together, we demonstrated that colon rectal tumor cells can secrete DR5-coated EVs, and this can cause TRAIL resistance. This is to our knowledge a novel finding and provides new insights into understanding TRAIL sensitivity.
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The remarkable pro-apoptotic properties of tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) have led to considerable interest in this protein as a potential anticancer therapeutic. However, TRAIL is largely ineffective in inducing apoptosis in certain cancer cells, and the mechanisms underlying this selectivity are unknown. In colon adenocarcinomas, posttranslational modifications including O- and N- glycosylation of death receptors were found to correlate with TRAIL-induced apoptosis. Additionally, mRNA levels of fucosyltransferase 3 (FUT3) and 6 (FUT6) were found to be high in the TRAIL-sensitive colon adenocarcinoma cell line COLO 205. In this study, we use agonistic receptor-specific TRAIL variants to dissect the contribution of FUT3 and FUT6-mediated fucosylation to TRAIL-induced apoptosis via its two death receptors, DR4 and DR5. Triggering of apoptosis by TRAIL revealed that the low FUT3/6-expressing cells DLD-1 and HCT 116 are insensitive to DR5 but not to DR4-mediated apoptosis. By contrast, efficient apoptosis is mediated via both receptors in high FUT3/6-expressing COLO 205 cells. The reconstitution of FUT3/6 expression in DR5-resistant cells completely restored TRAIL sensitivity via this receptor, while only marginally enhancing apoptosis via DR4 at lower TRAIL concentrations. Interestingly, we observed that induction of the salvage pathway by external administration of l-fucose restores DR5-mediated apoptosis in both DLD-1 and HCT 116 cells. Finally, we show that fucosylation influences the ligand-independent receptor association that leads to increased death inducing signalling complex (DISC) formation and caspase-8 activation. Taken together, these results provide evidence for the differential impact of fucosylation on signalling via DR4 or DR5. These findings provide novel opportunities to enhance TRAIL sensitivity in colon adenocarcinoma cells that are highly resistant to DR5-mediated apoptosis.
Assuntos
Fucosiltransferases/metabolismo , Regulação Neoplásica da Expressão Gênica , Processamento de Proteína Pós-Traducional , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/genética , Fucose/metabolismo , Fucosiltransferases/genética , Glicosilação , Células HCT116 , Humanos , Especificidade de Órgãos , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/genética , Transdução de Sinais , Ligante Indutor de Apoptose Relacionado a TNF/genética , Ligante Indutor de Apoptose Relacionado a TNF/metabolismoRESUMO
Bone is a dynamic tissue that is maintained by continuous renewal. An imbalance in bone resorption and bone formation can lead to a range of disorders, such as osteoporosis. The receptor activator of NF-κB (RANK)-RANK-ligand (RANKL) pathway plays a major role in bone remodeling. Here, we investigated the effect of mutations at position I248 in the DE-loop of murine RANKL on the interaction of RANKL with RANK, and subsequent activation of osteoclastogenesis. Two single mutants, RANKL I248Y and I248K, were found to maintain binding and have the ability to reduce wild-type RANKL-induced osteoclastogenesis. The generation of RANK-antagonists is a promising strategy for the exploration of new therapeutics against osteoporosis.
Assuntos
Mutação , Osteoclastos/metabolismo , Osteogênese , Ligante RANK/metabolismo , Receptor Ativador de Fator Nuclear kappa-B/metabolismo , Substituição de Aminoácidos , Animais , Biologia Computacional , Transferência de Energia , Sistemas Inteligentes , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas Imobilizadas/química , Proteínas Imobilizadas/metabolismo , Cinética , Camundongos , Mutagênese Sítio-Dirigida , Osteoclastos/citologia , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Multimerização Proteica , Ligante RANK/química , Ligante RANK/genética , Células RAW 264.7 , Receptor Ativador de Fator Nuclear kappa-B/química , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismoRESUMO
Analysis of coupled variables is a core concept of cell biological inference, with co-localization of two molecules as a proxy for protein interaction being a ubiquitous example. However, external effectors may influence the observed co-localization independently from the local interaction of two proteins. Such global bias, although biologically meaningful, is often neglected when interpreting co-localization. Here, we describe DeBias, a computational method to quantify and decouple global bias from local interactions between variables by modeling the observed co-localization as the cumulative contribution of a global and a local component. We showcase four applications of DeBias in different areas of cell biology, and demonstrate that the global bias encapsulates fundamental mechanistic insight into cellular behavior. The DeBias software package is freely accessible online via a web-server at https://debias.biohpc.swmed.edu.
Assuntos
Biologia Computacional/métodos , Técnicas Citológicas/métodos , Biologia de Sistemas/métodos , SoftwareRESUMO
Signaling receptors are internalized and regulated by clathrin-mediated endocytosis (CME). Two clathrin light chain isoforms, CLCa and CLCb, are integral components of the endocytic machinery whose differential functions remain unknown. We report that CLCb is specifically upregulated in non-small-cell lung cancer (NSCLC) cells and is associated with poor patient prognosis. Engineered single CLCb-expressing NSCLC cells, as well as "switched" cells that predominantly express CLCb, exhibit increased rates of CME and altered clathrin-coated pit dynamics. This "adaptive CME" resulted from upregulation of dynamin-1 (Dyn1) and its activation through a positive feedback loop involving enhanced epidermal growth factor (EGF)-dependent Akt/GSK3ß phosphorylation. CLCb/Dyn1-dependent adaptive CME selectively altered EGF receptor trafficking, enhanced cell migration in vitro, and increased the metastatic efficiency of NSCLC cells in vivo. We define molecular mechanisms for adaptive CME in cancer cells and a role for the reciprocal crosstalk between signaling and CME in cancer progression.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/patologia , Cadeias Leves de Clatrina/metabolismo , Clatrina/metabolismo , Dinamina I/metabolismo , Endocitose , Receptores ErbB/metabolismo , Neoplasias Pulmonares/patologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Carcinoma Pulmonar de Células não Pequenas/genética , Linhagem Celular Tumoral , Movimento Celular , Invaginações Revestidas da Membrana Celular/metabolismo , Endossomos/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Glicogênio Sintase Quinase 3 beta/metabolismo , Humanos , Neoplasias Pulmonares/genética , Camundongos Nus , Metástase Neoplásica , Fosforilação , Transporte Proteico , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fatores de Risco , Transdução de Sinais , Análise de Sobrevida , Regulação para Cima/genéticaRESUMO
Clathrin-mediated endocytosis (CME) constitutes the major pathway for uptake of signaling receptors into eukaryotic cells. As such, CME regulates signaling from cell-surface receptors, but whether and how specific signaling receptors reciprocally regulate the CME machinery remains an open question. Although best studied for its role in membrane fission, the GTPase dynamin also regulates early stages of CME. We recently reported that dynamin-1 (Dyn1), previously assumed to be neuron-specific, can be selectively activated in cancer cells to alter endocytic trafficking. Here we report that dynamin isoforms differentially regulate the endocytosis and apoptotic signaling downstream of TNF-related apoptosis-inducing ligand-death receptor (TRAIL-DR) complexes in several cancer cells. Whereas the CME of constitutively internalized transferrin receptors is mainly dependent on the ubiquitously expressed Dyn2, TRAIL-induced DR endocytosis is selectively regulated by activation of Dyn1. We show that TRAIL stimulation activates ryanodine receptor-mediated calcium release from endoplasmic reticulum stores, leading to calcineurin-mediated dephosphorylation and activation of Dyn1, TRAIL-DR endocytosis, and increased resistance to TRAIL-induced apoptosis. TRAIL-DR-mediated ryanodine receptor activation and endocytosis is dependent on early caspase-8 activation. These findings delineate specific mechanisms for the reciprocal crosstalk between signaling and the regulation of CME, leading to autoregulation of endocytosis and signaling downstream of surface receptors.
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Apoptose/fisiologia , Dinamina I/metabolismo , Endocitose/fisiologia , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Sinalização do Cálcio , Caspase 8/metabolismo , Linhagem Celular Tumoral , Clatrina/metabolismo , Humanos , Modelos Biológicos , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Transdução de SinaisRESUMO
The ability of cancer cells to degrade the extracellular matrix and invade interstitial tissues contributes to their metastatic potential. We recently showed that overexpression of sorting nexin 9 (SNX9) leads to increased cell invasion and metastasis in animal models, which correlates with increased SNX9 protein expression in metastases from human mammary cancers. Here, we report that SNX9 expression is reduced relative to neighboring normal tissues in primary breast tumors, and progressively reduced in more aggressive stages of non-small-cell lung cancers. We show that SNX9 is localized at invadopodia where it directly binds the invadopodia marker TKS5 and negatively regulates invadopodia formation and function. SNX9 depletion increases invadopodia number and the local recruitment of MT1-MMP by decreasing its internalization. Together, these effects result in increased localized matrix degradation. We further identify SNX9 as a Src kinase substrate and show that this phosphorylation is important for SNX9 activity in regulating cell invasion, but is dispensable for its function in regulating invadopodia. The diversified changes associated with SNX9 expression in cancer highlight its importance as a central regulator of cancer cell behavior.
Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Podossomos/metabolismo , Nexinas de Classificação/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Biomarcadores Tumorais/metabolismo , Linhagem Celular Tumoral , Endocitose , Feminino , Células HEK293 , Humanos , Metaloproteinase 14 da Matriz/metabolismo , Fosforilação , Ligação Proteica , Transporte Proteico , Especificidade por Substrato , Quinases da Família src/metabolismoRESUMO
Despite current advances in cancer research, metastasis remains the leading factor in cancer-related deaths. Here, we identify sorting nexin 9 (SNX9) as a new regulator of breast cancer metastasis. We detected an increase in SNX9 expression in human breast cancer metastases compared with primary tumors and demonstrated that SNX9 expression in MDA-MB-231 breast cancer cells is necessary to maintain their ability to metastasize in a chick embryo model. Reciprocally, SNX9 knockdown impairs the process. In vitro studies using several cancer cell lines derived from a variety of human tumors revealed a role for SNX9 in cell invasion and identified mechanisms responsible for this novel function. We showed that SNX9 controls the activation of RhoA and Cdc42 GTPases and also regulates cell motility via the modulation of well-known molecules involved in metastasis, namely RhoA-ROCK and N-WASP. In addition, we have discovered that SNX9 is required for RhoGTPase-dependent, clathrin-independent endocytosis, and in this capacity, can functionally substitute to the bona fide Rho GAP, GRAF1 (GTPase Regulator Associated with Focal Adhesion Kinase). Together, our data establish novel roles for SNX9 as a multifunctional protein scaffold that regulates, and potentially coordinates, several cellular processes that together can enhance cancer cell metastasis.
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In subcellular light-sheet fluorescence microscopy (LSFM) of adherent cells, glass substrates are advantageously rotated relative to the excitation and emission light paths to avoid glass-induced optical aberrations. Because cells are spread across the sample volume, three-dimensional imaging requires a light-sheet with a long propagation length, or rapid sample scanning. However, the former degrades axial resolution and/or optical sectioning, while the latter mechanically perturbs sensitive biological specimens on pliant biomimetic substrates (e.g., collagen and basement membrane). Here, we use aberration-free remote focusing to diagonally sweep a narrow light-sheet along the sample surface, enabling multicolor imaging with high spatiotemporal resolution. Further, we implement a dithered Gaussian lattice to minimize sample-induced illumination heterogeneities, significantly improving signal uniformity. Compared with mechanical sample scanning, we drastically reduce sample oscillations, allowing us to achieve volumetric imaging at speeds of up to 3.5 Hz for thousands of Z-stacks. We demonstrate the optical performance with live-cell imaging of microtubule and actin cytoskeletal dynamics, phosphoinositide signaling, clathrin-mediated endocytosis, polarized blebbing, and endocytic vesicle sorting. We achieve three-dimensional particle tracking of clathrin-associated structures with velocities up to 4.5 µm/s in a dense intracellular environment, and show that such dynamics cannot be recovered reliably at lower volumetric image acquisition rates using experimental data, numerical simulations, and theoretical modeling.
Assuntos
Imageamento Tridimensional/métodos , Microscopia/métodos , Citoesqueleto de Actina/metabolismo , Adesão Celular , Linhagem Celular , Endossomos/metabolismo , Espaço Extracelular/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Humanos , Transdução de SinaisRESUMO
Metastasis is a multistep process requiring cancer cell signaling, invasion, migration, survival, and proliferation. These processes require dynamic modulation of cell surface proteins by endocytosis. Given this functional connection, it has been suggested that endocytosis is dysregulated in cancer. To test this, we developed In-Cell ELISA assays to measure three different endocytic pathways: clathrin-mediated endocytosis, caveolae-mediated endocytosis, and clathrin-independent endocytosis and compared these activities using two different syngeneic models for normal and oncogene-transformed human lung epithelial cells. We found that all endocytic activities were reduced in the transformed versus normal counterparts. However, when we screened 29 independently isolated non-small cell lung cancer (NSCLC) cell lines to determine whether these changes were systematic, we observed significant heterogeneity. Nonetheless, using hierarchical clustering based on their combined endocytic properties, we identified two phenotypically distinct clusters of NSCLCs. One co-clustered with mutations in KRAS, a mesenchymal phenotype, increased invasion through collagen and decreased growth in soft agar, whereas the second was enriched in cells with an epithelial phenotype. Interestingly, the two clusters also differed significantly in clathrin-independent internalization and surface expression of CD44 and CD59. Taken together, our results suggest that endocytotic alterations in cancer cells that affect cell surface expression of critical molecules have a significant influence on cancer-relevant phenotypes, with potential implications for interventions to control cancer by modulating endocytic dynamics.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/metabolismo , Endocitose , Neoplasias Pulmonares/metabolismo , Antígenos CD59/biossíntese , Carcinoma Pulmonar de Células não Pequenas/patologia , Cavéolas/metabolismo , Adesão Celular , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Movimento Celular , Proliferação de Células , Clatrina/metabolismo , Colágeno/genética , Humanos , Receptores de Hialuronatos/biossíntese , Neoplasias Pulmonares/patologia , Invasividade Neoplásica , Proteínas Proto-Oncogênicas p21(ras)/genética , Mucosa Respiratória/metabolismo , Mucosa Respiratória/patologiaRESUMO
Clathrin-mediated endocytosis (CME) regulates signaling from the plasma membrane. Analysis of clathrin-coated pit (CCP) dynamics led us to propose the existence of a rate-limiting, regulatory step(s) that monitor the fidelity of early stages in CCP maturation. Here we show that nascent endocytic vesicles formed in mutant cells displaying rapid, dysregulated CME are defective in early endosomal trafficking, maturation and acidification, confirming the importance of this "checkpoint." Dysregulated CME also alters EGF receptor signaling and leads to constitutive activation of the protein kinase Akt. Dynamin-1, which was thought to be neuron specific, is activated by the Akt/GSK3ß signaling cascade in non-neuronal cells to trigger rapid, dysregulated CME. Acute activation of dynamin-1 in RPE cells by inhibition of GSK3ß accelerates CME, alters CCP dynamics and, unexpectedly, increases the rate of CCP initiation. CRISPR-Cas9n-mediated knockout and reconstitution studies establish that dynamin-1 is activated by Akt/GSK3ß signaling in H1299 non-small lung cancer cells. These findings provide direct evidence for an isoform-specific role for dynamin in regulating CME and reveal a feed-forward pathway that could link signaling from cell surface receptors to the regulation of CME.
Assuntos
Dinamina I/metabolismo , Endocitose , Células Epiteliais/fisiologia , Quinase 3 da Glicogênio Sintase/metabolismo , Mapas de Interação de Proteínas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Linhagem Celular , Vesículas Revestidas por Clatrina/metabolismo , Glicogênio Sintase Quinase 3 beta , HumanosRESUMO
The iron binding siderophore pyoverdine constitutes a major adaptive factor contributing to both virulence and survival in fluorescent pseudomonads. For decades, pyoverdine production has allowed the identification and classification of fluorescent and nonfluorescent pseudomonads. Here, we demonstrate that PvdP, a periplasmic enzyme of previously unknown function, is a tyrosinase required for the maturation of the pyoverdine chromophore in Pseudomonas aeruginosa. PvdP converts the nonfluorescent ferribactin, containing two iron binding groups, into a fluorescent pyoverdine, forming a strong hexadentate complex with ferrous iron, by three consecutive oxidation steps. PvdP represents the first characterized member of a small family of tyrosinases present in fluorescent pseudomonads that are required for siderophore maturation and are capable of acting on large peptidic substrates.
Assuntos
Proteínas de Bactérias/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Monofenol Mono-Oxigenase/metabolismo , Oligopeptídeos/metabolismo , Pseudomonas aeruginosa/enzimologia , Proteínas de Bactérias/genética , Domínio Catalítico , Regulação Bacteriana da Expressão Gênica/fisiologia , Modelos Moleculares , Monofenol Mono-Oxigenase/genética , Oligopeptídeos/genética , Filogenia , Conformação Proteica , Transporte Proteico , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismoRESUMO
The use of enzymes to interfere with quorum sensing represents an attractive strategy to fight bacterial infections. We used PvdQ, an effective quorum-quenching enzyme from Pseudomonas aeruginosa, as a template to generate an acylase able to effectively hydrolyze C8-HSL, the major communication molecule produced by the Burkholderia species. We discovered that the combination of two single mutations leading to variant PvdQ(Lα146W,Fß24Y) conferred high activity toward C8-HSL. Exogenous addition of PvdQ(Lα146W,Fß24Y) dramatically decreased the amount of C8-HSL present in Burkholderia cenocepacia cultures and inhibited a quorum sensing-associated phenotype. The efficacy of this PvdQ variant to combat infections in vivo was further confirmed by its ability to rescue Galleria mellonella larvae upon infection, demonstrating its potential as an effective agent toward Burkholderia infections. Kinetic analysis of the enzymatic activities toward 3-oxo-C12-L-HSL and C8-L-HSL corroborated a substrate switch. This work demonstrates the effectiveness of quorum-quenching acylases as potential novel antimicrobial drugs. In addition, we demonstrate that their substrate range can be easily switched, thereby paving the way to selectively target only specific bacterial species inside a complex microbial community.
Assuntos
Amidoidrolases/metabolismo , Burkholderia cenocepacia/patogenicidade , Percepção de Quorum , Amidoidrolases/química , Animais , Burkholderia cenocepacia/enzimologia , Cinética , Larva/microbiologia , Modelos Moleculares , Mariposas/crescimento & desenvolvimento , Mariposas/microbiologia , Especificidade por Substrato , VirulênciaRESUMO
The bone marrow microenvironment provides important signals for the survival and proliferation of hematopoietic and malignant cells. In multiple myeloma, plasma cells are surrounded by stromal cells including osteoblasts. These stromal cells protect multiple myeloma cells from apoptosis induced by chemotherapeutic agents. Osteoprotegerin (OPG), a soluble receptor of the cytokine TNF-related apoptosis-inducing ligand (TRAIL), is secreted by osteoblasts and has been implicated in the prevention of cell death induced by TRAIL in malignant cells. Previously, we have designed death receptor-specific TRAIL variants that induce apoptosis exclusively via one of its death receptors. Here, we have studied in detail the interaction between recombinant human (rhTRAIL) variants and OPG. We show that a DR5-specific variant (rhTRAIL D269H/E195R) displays a significantly decreased affinity to OPG. Furthermore, this rhTRAIL variant shows a much higher activity when compared with rhTRAIL WT and retains its effectiveness in inducing cell death in multiple myeloma cell lines, in the presence of OPG secreted by stromal cells. We also demonstrate that stromal cells are largely insensitive to high concentrations of this rhTRAIL variant. In conclusion, rhTRAIL D269H/E195R is a potential therapy for multiple myeloma due to its high effectiveness and diminished binding to OPG.
Assuntos
Medula Óssea/metabolismo , Mutação , Osteoprotegerina/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/genética , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Substituição de Aminoácidos , Apoptose/efeitos dos fármacos , Ligação Competitiva , Western Blotting , Medula Óssea/efeitos dos fármacos , Medula Óssea/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Humanos , Mieloma Múltiplo/genética , Mieloma Múltiplo/metabolismo , Mieloma Múltiplo/patologia , Proteínas Mutantes/metabolismo , Proteínas Mutantes/farmacologia , Osteoprotegerina/genética , Osteoprotegerina/farmacologia , Ligação Proteica , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Ressonância de Plasmônio de Superfície , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Microambiente Tumoral/efeitos dos fármacos , Microambiente Tumoral/genéticaRESUMO
Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumour in humans and is highly resistant to current treatment modalities. We have explored the combined treatment of the endoplasmic reticulum (ER) stress-inducing agent 2,5-dimethyl-celecoxib (DMC) and TNF-related apoptosis-inducing ligand (TRAIL WT) or the DR5-specific TRAIL D269H/E195R variant as a potential new strategy to eradicate GBM cells using TRAIL-resistant and -sensitive GBM cells. GBM cell lines were investigated for their sensitivity to TRAIL, DMC and combination of both agents. Cell viability was measured by MTS assay and apoptosis was assessed by Annexin V/PI and acridine orange staining. Caspase activation and protein expression levels were analysed with Western blotting. Death Receptor (DR) cell surface expression levels were quantified by flow cytometry. DR5 expression was increased in U87 cells by ectopic expression using a retroviral plasmid and survivin expression was silenced using specific siRNAs. We demonstrate that A172 expresses mainly DR5 on the cell surface and that these cells show increased sensitivity for the DR5-specific rhTRAIL D269H/E195R variant. In contrast, U87 cells show low DR cell surface levels and is insensitive via both DR4 and DR5. We determined that DMC treatment displays a dose-dependent reduction in cell viability against a number of GBM cells, associated with ER stress induction, as shown by the up-regulation of glucose-regulated protein 78 (GRP78) and CCAAT/-enhancer-binding protein homologous protein (CHOP) in A172 and U87 cells. The dramatic decrease in cell viability is not accompanied by a correspondent increase in Annexin V/PI or caspase activation typically seen in apoptotic or/and necrotic cells within 24h of treatment. Although DMC did not affect DR5 expression in the GBM cells, it increased TRAIL-induced caspase-8 activation in both TRAIL-sensitive and -resistant cells, indicating that DMC potentiates initiator caspase activation in these cells. In A172 cells, sub-toxic concentrations of DMC greatly potentiated TRAIL-induced apoptosis. Furthermore, DMC strongly reduced survivin expression in A172 and U87 cells and silencing of this anti-apoptotic protein partially sensitized cells to TRAIL-induced apoptosis. Our findings corroborate that DMC is a promising agent against GBM, and uncovers a potential synergistic cooperation with TRAIL in this highly malignant cancer.
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[This corrects the article DOI: 10.1186/2193-1801-3-495.].
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The major challenge in targeted protein quantification by LC-MS/MS in serum lies in the complexity of the biological matrix with regard to the wide diversity of proteins and their extremely large dynamic concentration range. In this study, an LC-MS/MS method was developed for the simultaneous quantification of the 60-kDa biopharmaceutical proteins recombinant human tumor necrosis factor-related apoptosis-inducing ligand wild type (rhTRAIL(WT)) and its death receptor 4 (DR4)-specific variant rhTRAIL(4C7) in human and mouse serum. Selective enrichment of TRAIL was accomplished by immobilized metal affinity chromatography (IMAC), which was followed by tryptic digestion of the enriched sample and quantification of a suitable signature peptide. For absolute quantification, (15)N-metabolically labeled internal standards of rhTRAIL(WT) and rhTRAIL(4C7) were used. Since the signature peptides that provided the highest sensitivity and allowed discrimination between rhTRAIL(WT) and rhTRAIL(4C7) contained methionine residues, we oxidized these quantitatively to their sulfoxides by the addition of 0.25% (w/w) hydrogen peroxide. The final method has a lower limit of quantification of 20 ng/mL (ca. 350 pM) and was fully validated according to current international guidelines for bioanalysis. To show the applicability of the LC-MS/MS method for pharmacokinetic studies, we quantified rhTRAIL(WT) and rhTRAIL(4C7) simultaneously in serum from mice injected intraperitoneally at a dose of 5 mg/kg for each protein. This is the first time that two variants of rhTRAIL differing by only a few amino acids have been analyzed simultaneously in serum, an approach that is not possible by conventional enzyme-linked immuno-sorbent assay (ELISA) analysis.
Assuntos
Cromatografia Líquida/métodos , Metionina/química , Fragmentos de Peptídeos/sangue , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/sangue , Proteínas Recombinantes/sangue , Espectrometria de Massas em Tandem/métodos , Animais , Cromatografia de Afinidade , Eletroforese em Gel de Poliacrilamida , Humanos , Camundongos , Camundongos Endogâmicos C57BLRESUMO
The redesign of enzymes to produce catalysts for a predefined transformation remains a major challenge in protein engineering. Here, we describe the structure-based engineering of methylaspartate ammonia lyase (which in nature catalyses the conversion of 3-methylaspartate to ammonia and 2-methylfumarate) to accept a variety of substituted amines and fumarates and catalyse the asymmetric synthesis of aspartic acid derivatives. We obtained two single-active-site mutants, one exhibiting a wide nucleophile scope including structurally diverse linear and cyclic alkylamines and one with broad electrophile scope including fumarate derivatives with alkyl, aryl, alkoxy, aryloxy, alkylthio and arylthio substituents at the C2 position. Both mutants have an enlarged active site that accommodates the new substrates while retaining the high stereo- and regioselectivity of the wild-type enzyme. As an example, we demonstrate a highly enantio- and diastereoselective synthesis of threo-3-benzyloxyaspartate (an important inhibitor of neuronal excitatory glutamate transporters in the brain).
Assuntos
Aminoácidos/síntese química , Amônia-Liases/química , Catálise , Domínio Catalítico , Cristalografia por Raios X , Modelos Moleculares , Mutagênese Sítio-DirigidaRESUMO
Previously studied Bacillus subtilis carboxylesterases (CesA and CesB) have potential for the kinetic resolution of racemic esters of 1,2-O-isopropylideneglycerol (IPG). CesA exhibits high activity but low enantioselectivity towards IPG-butyrate and IPG-caprylate, while the more enantioselective CesB does not process IPG-butyrate and exhibits several-fold lower activity than CesA towards IPG-caprylate. A sequence and structure comparison allowed us to identify active site residues that may cause the difference in (enantio)selectivities of CesA and CesB towards these IPG esters. This structure-based approach led to the identification of two active site residues in CesA (F166 and F182), as promising candidates for mutagenesis in order to enhance its enantioselectivity. Mutagenesis of positions 166 and 182 in CesA yielded novel variants with enhanced enantioselectivity and without significant loss of catalytic activity. For IPG-butyrate, a CesA double mutant F166V/F182C (ER=13) was generated showing a â¼13-fold increased enantioselectivity as compared to wild-type CesA (E=1). For IPG-caprylate, we designed a CesA double mutant F166V/F182Y (ER=9) displaying a â¼5-fold increased enantioselectivity as compared to the wild-type enzyme (ER=2). These findings, combined with the results of molecular docking experiments, demonstrate the importance of residues at positions 166 and 182 for the enantioselectivity of CesA, and may contribute to the development of efficient biocatalysts.