RESUMO
The SARS-CoV-2 main protease (Mpro ) holds significant importance as a biological target in combating coronaviruses due to its importance in virus replication. Considering the emergence of novel SARS-CoV-2 variants and the mutations observed in the Mpro sequence, we hypothesized that these mutations may have a potential impact on the protease's specificity. To test this, we expressed Mpro corresponding to the original strain and variants Beta1, Beta2, and Omicron and analyzed their activity on protein-based and peptide substrates. Although we observed differential activity on the protein-based substrate, there was very little difference when analyzed on the peptide substrate. We conclude that mutations on the Mpro sequence, despite having a minor effect on a peptide substrate cleavage, did not change the catalytic site environment enough to build resistance to inhibition. Therefore, we propose that inhibitors initially designed for the Mpro of the original strain will be effective in all the variants. Thus, Mpro is likely to continue to be a target of therapeutic interest as mutations in its sequence are rare and, as we show here, have a minor effect on the protease's recognition of peptide-based molecules.
Assuntos
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/genética , COVID-19/genética , Proteínas não Estruturais Virais/genética , Peptídeos/genética , Proteases 3C de Coronavírus/genética , Inibidores de Proteases/química , Antivirais/farmacologia , Peptídeo HidrolasesRESUMO
Many proinflammatory proteins are released via the necrotic form of cell death known as pyroptosis. Sometimes known as gasdermin D (GSDMD) dependent cell death, pyroptosis results from the formation of pores in the plasma membrane leading to eventual cell lysis. Seeking to understand the magnitude of this cell lysis we measured the size of proteins released during pyroptosis. We demonstrate that there is no restriction on the size of soluble proteins released during pyroptosis even at early timepoints. However, even though large molecules can exit the dying cell, organelles are retained within it. This observation indicates that complete cell rupture may not be a consequence of pyroptosis, and that plasma membrane architecture is retained.
Assuntos
Inflamassomos , Peptídeos e Proteínas de Sinalização Intracelular , Inflamassomos/metabolismo , Piroptose , Proteínas Reguladoras de Apoptose/metabolismo , Organelas/metabolismoRESUMO
Purpose: Retinal vein occlusion (RVO) is a sight-threatening condition typically treated with intravitreal injection of vascular endothelial growth factor (VEGF) antagonists. Treatment response to anti-VEGF therapies is highly variable, with poor visual outcomes and treatment response in patients with significant retinal nonperfusion following RVO. Recently, caspase-9 has been identified as a potent regulator of edema, gliosis, and neuronal dysfunction during acute retinal hypoxia. The purpose of this study was to compare the therapeutic effect of caspase-9 inhibition against VEGF-neutralization in an established mouse model of RVO. Methods: Adult male C57Bl/6 J mice were randomized to induction of RVO and treatment with either vehicle, intravitreal injection of anti-VEGF antibody, topical administration of a selective caspase-9 inhibitor (Pen1-XBir3), or a combination therapy. Animals were followed on days 1, 2, and 8 after RVO with fundus retinal imaging, and with optical coherence tomography (OCT) to capture retinal swelling, capillary nonperfusion (measured by disorganization of retinal inner layers, DRIL), hyperreflective foci (HRF), and retinal atrophy. Focal electroretinography (ERG) measurements were performed on day 7. Histology was performed on retinal sections from day 8. Results: Both VEGF neutralization and caspase-9 inhibition showed significant retinal protection from RVO compared to vehicle treatment arm. Retinal reperfusion of occluded veins was accelerated in eyes receiving caspase-9 inhibitor, but not significantly different from vehicle in the anti-VEGF group. Retinal edema was suppressed in all treatment groups, with approximately 2-fold greater edema reduction with caspase-9 inhibition compared to VEGF neutralization. HRF were reduced similarly across all treatment groups compared to vehicle. Retinal detachment was reduced only in eyes treated with caspase-9 inhibitor monotherapy. Caspase-9 inhibition reduced retinal atrophy and preserved ERG response; VEGF neutralization did not prevent neurodegeneration following RVO. Conclusion: Caspase-9 inhibition confers stronger neuronal and vascular protection compared to VEGF neutralization in the mouse laser-induced model of RVO.
RESUMO
Necroptosis is a form of regulated cell death triggered by various host and pathogen-derived molecules during infection and inflammation. The essential step leading to necroptosis is phosphorylation of the mixed lineage kinase domain-like protein by receptor-interacting protein kinase 3. Caspase-8 cleaves receptor-interacting protein kinases to block necroptosis, so synthetic caspase inhibitors are required to study this process in experimental models. However, it is unclear how caspase-8 activity is regulated in a physiological setting. The active site cysteine of caspases is sensitive to oxidative inactivation, so we hypothesized that oxidants generated at sites of inflammation can inhibit caspase-8 and promote necroptosis. Here, we discovered that hypothiocyanous acid (HOSCN), an oxidant generated in vivo by heme peroxidases including myeloperoxidase and lactoperoxidase, is a potent caspase-8 inhibitor. We found HOSCN was able to promote necroptosis in mouse fibroblasts treated with tumor necrosis factor. We also demonstrate purified caspase-8 was inactivated by low concentrations of HOSCN, with the predominant product being a disulfide-linked dimer between Cys360 and Cys409 of the large and small catalytic subunits. We show oxidation still occurred in the presence of reducing agents, and reduction of the dimer was slow, consistent with HOSCN being a powerful physiological caspase inhibitor. While the initial oxidation product is a dimer, further modification also occurred in cells treated with HOSCN, leading to higher molecular weight caspase-8 species. Taken together, these findings indicate major disruption of caspase-8 function and suggest a novel mechanism for the promotion of necroptosis at sites of inflammation.
Assuntos
Caspase 8 , Necroptose , Oxidantes , Fatores de Necrose Tumoral , Animais , Camundongos , Caspase 8/química , Caspase 8/metabolismo , Inflamação/metabolismo , Necroptose/efeitos dos fármacos , Oxidantes/metabolismo , Oxidantes/farmacologia , Oxirredução/efeitos dos fármacos , Fatores de Necrose Tumoral/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/enzimologia , Fibroblastos/metabolismo , Peroxidase , Lactoperoxidase , Domínio CatalíticoRESUMO
A patient diagnosed with multiple myeloma, bicuspid aortic valve, and Von Hippel-Lindau syndrome underwent whole-exome sequencing seeking a unified genetic cause for these three pathologies. The patient possessed a single-point mutation of arginine to cysteine (R24C) in the N-terminal region(pro-domain) of matrix metalloproteinase 9 (MMP-9). The pro-domain interacts with the catalytic site of this enzyme rendering it inactive. MMP-9 has previously been associated with all three pathologies suffered by the patient. We hypothesized that the observed mutation in the pro-domain would influence the activity of this enzyme. We expressed recombinant versions of MMP-9 and an investigation of their biochemical properties revealed that MMP-9 R24C is a constitutively active zymogen. To our knowledge, this is the first example of a mutation that discloses catalytic activity in the pro-form in any of the 24 human MMPs.
Assuntos
Doença da Válvula Aórtica Bicúspide , Mieloma Múltiplo , Doença de von Hippel-Lindau , Mutação com Ganho de Função , Humanos , Metaloproteinase 9 da Matriz/genética , Mieloma Múltiplo/complicações , Mieloma Múltiplo/genética , Doença de von Hippel-Lindau/complicações , Doença de von Hippel-Lindau/genéticaRESUMO
Pyroptosis is a mechanism of inflammatory cell death mediated by the activation of the prolytic protein gasdermin D by caspase-1, caspase-4, and caspase-5 in human, and caspase-1 and caspase-11 in mouse. In addition, caspase-1 amplifies inflammation by proteolytic activation of cytokine interleukin-1ß (IL-1ß). Modern mammals of the order Carnivora lack the caspase-1 catalytic domain but express an unusual version of caspase-4 that can activate both gasdermin D and IL-1ß. Seeking to understand the evolutionary origin of this caspase, we utilized the large amount of data available in public databases to perform ancestral sequence reconstruction of an inflammatory caspase of a Carnivora ancestor. We expressed the catalytic domain of this putative ancestor in Escherichia coli, purified it, and compared its substrate specificity on synthetic and protein substrates to extant caspases. We demonstrated that it activates gasdermin D but has reduced ability to activate IL-1ß. Our reconstruction suggests that caspase-1 was lost in a Carnivora ancestor, perhaps upon a selective pressure for which the generation of biologically active IL-1ß by caspase-1 was detrimental. We speculate that later, a Carnivora encountered selective pressures that required the production of IL-1ß, and caspase-4 subsequently gained this activity. This hypothesis would explain why extant Carnivora possess an inflammatory caspase with caspase-1 catalytic function placed on a caspase-4 scaffold.
Assuntos
Caspases , Animais , Carnívoros/genética , Carnívoros/metabolismo , Caspase 1/genética , Caspase 1/metabolismo , Caspases/genética , Caspases/metabolismo , Escherichia coli/genética , Inflamação/genética , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Proteínas de Ligação a Fosfato/genética , Proteínas de Ligação a Fosfato/metabolismo , Piroptose/fisiologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Seleção GenéticaRESUMO
Regulated cell death is defined as genetically encoded pathways that lead towards the demise of cells. In mammals, cell demise can be either inflammatory or non-inflammatory, depending on whether the mechanism of death results in cell rupture or not. Inflammatory cell death can lead towards acute and chronic disease. Therefore, it becomes important to distinguish the mechanisms that result in these different inflammatory cell death outcomes. Apoptosis is a non-inflammatory form of cell death where cells resist rupture. In contrast, pyroptosis and necroptosis are inflammatory forms of cell death principally because of release of pro-inflammatory mediators from cells undergoing lysis. This review focusses on the mechanisms of these different cell death outcomes with specific emphasis on the caspase family of proteolytic enzymes.
Assuntos
Caspases , Inflamassomos , Animais , Humanos , Caspases/genética , Caspases/metabolismo , Inflamassomos/metabolismo , Piroptose , Necroptose , Inflamação , Apoptose/genética , MamíferosRESUMO
Zoonotic pathogens, such as COVID-19, reside in animal hosts before jumping species to infect humans. The Carnivora, like mink, carry many zoonoses, yet how diversity in host immune genes across species affect pathogen carriage is poorly understood. Here, we describe a progressive evolutionary downregulation of pathogen-sensing inflammasome pathways in Carnivora. This includes the loss of nucleotide-oligomerization domain leucine-rich repeat receptors (NLRs), acquisition of a unique caspase-1/-4 effector fusion protein that processes gasdermin D pore formation without inducing rapid lytic cell death, and the formation of a caspase-8 containing inflammasome that inefficiently processes interleukin-1ß. Inflammasomes regulate gut immunity, but the carnivorous diet has antimicrobial properties that could compensate for the loss of these immune pathways. We speculate that the consequences of systemic inflammasome downregulation, however, can impair host sensing of specific pathogens such that they can reside undetected in the Carnivora.
Assuntos
Carnívoros/metabolismo , Evolução Molecular , Inflamassomos/metabolismo , Zoonoses/patologia , Animais , Caspase 1/genética , Caspase 1/metabolismo , Caspase 8/metabolismo , Caspases Iniciadoras/genética , Caspases Iniciadoras/metabolismo , Morte Celular , Linhagem Celular , Humanos , Interleucina-1beta/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Proteínas NLR/genética , Proteínas NLR/metabolismo , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Salmonella typhi/patogenicidade , Zoonoses/imunologia , Zoonoses/parasitologiaRESUMO
Caspases are a family of enzymes that play roles in cell death and inflammation. It has been suggested that in the execution phase of the apoptotic pathway, caspase-3, -6 and -7 are involved. The substrate specificities of two proteases (caspases 3 and 7) are highly similar, which complicates the design of compounds that selectively interact with a single enzyme exclusively. The recognition of residues other than Asp in the P1 position of the substrate by caspase-3/-7 has been reported, promoting interest in the effects of phosphorylation of amino acids in the direct vicinity of the scissile bond. To evaluate conflicting reports on this subject, we synthesized a series of known caspase-3 and -7 substrates and phosphorylated analogs, performed enzyme kinetic assays and mapped the peptide cleavage sites using internally quenched fluorescent peptide substrates. Caspases 3 and 7 will tolerate pSer at the P1 position but only poorly at the P2' position. Our investigation demonstrates the importance of peptide length and composition in interpreting sequence/activity relationships. Based on the results, we conclude that the relationship between caspase-3/-7 and their substrates containing phosphorylated amino acids might depend on the steric conditions and not be directly connected with ionic interactions. Thus, the precise effect of phospho-amino acid residues located in the vicinity of the cleaved bond on the regulation of the substrate specificity of caspases remains difficult to predict. Our observations allow to predict that natural phosphorylated proteins may be cleaved by caspases, but only when extended substrate binding site interactions are satisfied.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/química , Caspase 3/metabolismo , Caspase 7/metabolismo , Fragmentos de Peptídeos/metabolismo , Proteólise , Serina/metabolismo , Fatores de Transcrição/química , Vimentina/química , Sítios de Ligação , Caspase 3/genética , Caspase 7/genética , Humanos , Cinética , Modelos Moleculares , Fosforilação , Serina/química , Especificidade por Substrato , Proteínas de Sinalização YAPRESUMO
Many proteases recognize their substrates with high specificities, with this in mind, it should theoretically be possible to utilize the substrate binding cleft of a protease as a scaffold to engineer an affinity reagent. In this study, we sought to develop reagents that would differentiate between substrates and products of proteolysis, based on a caspase 7 scaffold. Firstly, we engineered a form of caspase 7 that can undergo conversion to a substrate binding conformation without catalysis. Seeking to generate a product-only trap, we further engineered this construct by incorporating mutations that compensate for the generation of a negative charge in the neo C terminus of a newly generated product. This was accomplished with only three substitutions within the substrate binding cleft. Moreover, the affinity of the product trap for peptides was comparable to the affinity of caspase 7 to parental substrates. Finally, generation of a hybrid fluorescent protein with the product trap provided a reagent that specifically recognized apoptotic cells and highlights the versatility of such an approach in developing affinity and imaging agents for a variety of cysteine and serine proteases.
Assuntos
Caspase 7/genética , Proteínas Mutantes/metabolismo , Mutação , Engenharia de Proteínas/métodos , Apoptose/efeitos dos fármacos , Sítios de Ligação/genética , Caspase 7/química , Caspase 7/metabolismo , Linhagem Celular Tumoral , Endopeptidases/metabolismo , Humanos , Proteínas Mutantes/química , Proteínas Mutantes/genética , Ligação Proteica , Domínios Proteicos , Proteólise , Especificidade por Substrato , Ligante Indutor de Apoptose Relacionado a TNF/farmacologiaRESUMO
The subset of the proteome that contains enzymes in their catalytically active form can be interrogated by using probes targeted toward individual specific enzymes. A subset of such enzymes are proteases that are frequently studied with activity-based probes, small inhibitors equipped with a detectable tag, commonly a fluorophore. Due to the spectral overlap of these commonly used fluorophores, multiplex analysis becomes limited. To overcome this, we developed a series of protease-selective lanthanide-labeled probes compatible with mass cytometry giving us the ability to monitor the activity of multiple proteases in parallel. Using these probes, we were able to identify the distribution of four proteases with different active site geometries in three cell lines and peripheral blood mononuclear cells. This provides a framework for the use of mass cytometry for multiplexed enzyme activity detection.
Assuntos
Complexos de Coordenação/química , Elementos da Série dos Lantanídeos/química , Sondas Moleculares/química , Peptídeo Hidrolases/análise , Linhagem Celular , Complexos de Coordenação/síntese química , Humanos , Sondas Moleculares/síntese química , Estrutura Molecular , Peptídeo Hidrolases/metabolismoRESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Aza-peptide aldehydes and ketones are a new class of reversible protease inhibitors that are specific for the proteasome and clan CD cysteine proteases. We designed and synthesised aza-Leu derivatives that were specific for the chymotrypsin-like active site of the proteasome, aza-Asp derivatives that were effective inhibitors of caspases-3 and -6, and aza-Asn derivatives that inhibited S. mansoni and I. ricinus legumains. The crystal structure of caspase-3 in complex with our caspase-specific aza-peptide methyl ketone inhibitor with an aza-Asp residue at P1 revealed a covalent linkage between the inhibitor carbonyl carbon and the active site cysteinyl sulphur. Aza-peptide aldehydes and ketones showed no cross-reactivity towards cathepsin B or chymotrypsin. The initial in vitro selectivity of these inhibitors makes them suitable candidates for further development into therapeutic agents to potentially treat multiple myeloma, neurodegenerative diseases, and parasitic infections.
Assuntos
Aldeídos/farmacologia , Compostos Aza/farmacologia , Desenho de Fármacos , Cetonas/farmacologia , Peptídeos/farmacologia , Inibidores de Proteases/farmacologia , Aldeídos/química , Animais , Compostos Aza/química , Bovinos , Cristalografia por Raios X , Cisteína Endopeptidases/metabolismo , Relação Dose-Resposta a Droga , Humanos , Cetonas/química , Modelos Moleculares , Estrutura Molecular , Peptídeos/química , Inibidores de Proteases/síntese química , Inibidores de Proteases/química , Complexo de Endopeptidases do Proteassoma/metabolismo , Relação Estrutura-AtividadeRESUMO
Central nervous system ischemic injury features neuronal dysfunction, inflammation and breakdown of vascular integrity. Here we show that activation of endothelial caspase-9 after hypoxia-ischemia is a critical event in subsequent dysfunction of the blood-retina barrier, using a panel of interrelated ophthalmic in vivo imaging measures in a mouse model of retinal vein occlusion (RVO). Rapid nonapoptotic activation of caspase-9 and its downstream effector caspase-7 in endothelial cells promotes capillary ischemia and retinal neurodegeneration. Topical eye-drop delivery of a highly selective caspase-9 inhibitor provides morphological and functional retinal protection. Inducible endothelial-specific caspase-9 deletion phenocopies this protection, with attenuated retinal edema, reduced inflammation and preserved neuroretinal morphology and function following RVO. These results reveal a non-apoptotic function of endothelial caspase-9 which regulates blood-retina barrier integrity and neuronal survival, and identify caspase-9 as a therapeutic target in neurovascular disease.
Assuntos
Caspase 9/metabolismo , Hipóxia/metabolismo , Isquemia/metabolismo , Oclusão da Veia Retiniana/metabolismo , Lesões do Sistema Vascular/metabolismo , Animais , Barreira Hematorretiniana/metabolismo , Caspase 7/metabolismo , Caspase 9/efeitos dos fármacos , Caspase 9/genética , Morte Celular , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Feminino , Predisposição Genética para Doença/genética , Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Coelhos , Retina/metabolismo , Retina/patologia , Oclusão da Veia Retiniana/tratamento farmacológico , Oclusão da Veia Retiniana/patologia , Lesões do Sistema Vascular/patologiaRESUMO
Pyroptosis is the caspase-dependent inflammatory cell death mechanism that underpins the innate immune response against pathogens and is dysregulated in inflammatory disorders. Pyroptosis occurs via two pathways: the canonical pathway, signaled by caspase-1, and the noncanonical pathway, regulated by mouse caspase-11 and human caspase-4/5. All inflammatory caspases activate the pyroptosis effector protein gasdermin D, but caspase-1 mostly activates the inflammatory cytokine precursors prointerleukin-18 and prointerleukin-1ß (pro-IL18/pro-IL1ß). Here, in vitro cleavage assays with recombinant proteins confirmed that caspase-11 prefers cleaving gasdermin D over the pro-ILs. However, we found that caspase-11 recognizes protein substrates through a mechanism that is different from that of most caspases. Results of kinetics analysis with synthetic fluorogenic peptides indicated that P1'-P4', the C-terminal gasdermin D region adjacent to the cleavage site, influences gasdermin D recognition by caspase-11. Furthermore, introducing the gasdermin D P1'-P4' region into pro-IL18 enhanced catalysis by caspase-11 to levels comparable with that of gasdermin D cleavage. Pro-IL1ß cleavage was only moderately enhanced by similar substitutions. We conclude that caspase-11 specificity is mediated by the P1'-P4' region in its substrate gasdermin D, and similar experiments confirmed that the substrate specificities of the human orthologs of caspase-11, i.e. caspase-4 and caspase-5, are ruled by the same mechanism. We propose that P1'-P4'-based inhibitors could be exploited to specifically target inflammatory caspases.
Assuntos
Caspases/metabolismo , Inflamação/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Proteínas de Ligação a Fosfato/fisiologia , Piroptose , Animais , Catálise , Humanos , Imunidade Inata , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Proteínas de Ligação a Fosfato/química , Proteínas de Ligação a Fosfato/metabolismo , Proteólise , Especificidade por SubstratoRESUMO
Genetic polymorphisms in the region of the trimeric serine hydrolase high-temperature requirement 1 (HTRA1) are associated with increased risk of age-related macular degeneration (AMD) and disease progression, but the precise biological function of HtrA1 in the eye and its contribution to disease etiologies remain undefined. In this study, we have developed an HtrA1-blocking Fab fragment to test the therapeutic hypothesis that HtrA1 protease activity is involved in the progression of AMD. Next, we generated an activity-based small-molecule probe (ABP) to track target engagement in vivo. In addition, we used N-terminomic proteomic profiling in preclinical models to elucidate the in vivo repertoire of HtrA1-specific substrates, and identified substrates that can serve as robust pharmacodynamic biomarkers of HtrA1 activity. One of these HtrA1 substrates, Dickkopf-related protein 3 (DKK3), was successfully used as a biomarker to demonstrate the inhibition of HtrA1 activity in patients with AMD who were treated with the HtrA1-blocking Fab fragment. This pharmacodynamic biomarker provides important information on HtrA1 activity and pharmacological inhibition within the ocular compartment.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Anticorpos Anti-Idiotípicos/farmacologia , Atrofia Geográfica/tratamento farmacológico , Serina Peptidase 1 de Requerimento de Alta Temperatura A/genética , Degeneração Macular/tratamento farmacológico , Proteínas Adaptadoras de Transdução de Sinal/isolamento & purificação , Idoso , Animais , Anticorpos Anti-Idiotípicos/genética , Anticorpos Anti-Idiotípicos/imunologia , Biomarcadores/sangue , Progressão da Doença , Feminino , Predisposição Genética para Doença , Genótipo , Atrofia Geográfica/sangue , Atrofia Geográfica/genética , Atrofia Geográfica/imunologia , Serina Peptidase 1 de Requerimento de Alta Temperatura A/antagonistas & inibidores , Humanos , Fragmentos Fab das Imunoglobulinas/imunologia , Fragmentos Fab das Imunoglobulinas/farmacologia , Degeneração Macular/sangue , Degeneração Macular/genética , Degeneração Macular/imunologia , Masculino , Polimorfismo de Nucleotídeo Único/genética , Proteoma/genética , Proteoma/imunologia , Ratos , Retina/efeitos dos fármacos , Retina/imunologia , Retina/patologia , Bibliotecas de Moléculas Pequenas/farmacologiaAssuntos
Caspases/classificação , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/classificação , Proteínas de Plantas/classificação , Terminologia como Assunto , Animais , Caspases/química , Caspases/metabolismo , Consenso , Humanos , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/química , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
Since their discovery, the matrix metalloproteinase (MMP) family proteases have been considered as therapeutic targets in numerous diseases and disorders. Unfortunately, clinical trials with MMP inhibitors have failed to yield any clinical benefits of these inhibitors. These failures were largely due to a lack of MMP-selective agents; accordingly, it has become important to identify a platform with which high selectivity can be achieved. To this end, we propose using MMP-targeting antibodies that can achieve high specificity in interactions with their targets. Using a scaffold of single-domain antibodies, here we raised a panel of MMP10-selective antibodies through immunization of llamas, a member of the camelid family, whose members generate conventional heavy/light-chain antibodies and also smaller antibodies lacking light-chain and CH1 domains. We report the generation of a highly selective and tightly binding MMP10 inhibitor (Ki < 2 nm). Using bio-layer interferometry-based binding assays, we found that this antibody interacts with the MMP10 active site. Activity assays demonstrated that the antibody selectively inhibits MMP10 over its closest relative, MMP3. The ability of a single-domain antibody to discriminate between the most conserved MMP pair via an active site-directed mechanism of inhibition reported here supports the potential of this antibody as a broadly applicable scaffold for the development of selective, tightly binding MMP inhibitors.
Assuntos
Metaloproteinase 10 da Matriz/metabolismo , Inibidores de Metaloproteinases de Matriz/farmacologia , Anticorpos de Domínio Único/farmacologia , Animais , Camelídeos Americanos , Humanos , Imunização , Cinética , Biblioteca de Peptídeos , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/metabolismo , Especificidade por Substrato/efeitos dos fármacos , alfa 1-Antitripsina/metabolismoRESUMO
Neutrophils are primary host innate immune cells defending against pathogens. One proposed mechanism by which neutrophils prevent the spread of pathogens is NETosis, the extrusion of cellular DNA resulting in neutrophil extracellular traps (NETs). The protease neutrophil elastase (NE) has been implicated in the formation of NETs through proteolysis of nuclear proteins leading to chromatin decondensation. In addition to NE, neutrophils contain three other serine proteases that could compensate if the activity of NE was neutralized. However, whether they do play such a role is unknown. Thus, we deployed recently described specific inhibitors against all four of the neutrophil serine proteases (NSPs). Using specific antibodies to the NSPs along with our labeled inhibitors, we show that catalytic activity of these enzymes is not required for the formation of NETs. Moreover, the NSPs that decorate NETs are in an inactive conformation and thus cannot participate in further catalytic events. These results indicate that NSPs play no role in either NETosis or arming NETs with proteolytic activity.
Assuntos
Armadilhas Extracelulares/metabolismo , Neutrófilos/enzimologia , Serina Proteases/metabolismo , Animais , Anticorpos/química , Anticorpos/imunologia , Candida albicans/fisiologia , DNA/metabolismo , Escherichia coli/fisiologia , Armadilhas Extracelulares/efeitos dos fármacos , Humanos , Elastase de Leucócito/antagonistas & inibidores , Elastase de Leucócito/imunologia , Elastase de Leucócito/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Microscopia Confocal , Neutrófilos/efeitos dos fármacos , Piroptose/efeitos dos fármacos , Células RAW 264.7 , Serina Proteases/química , Serina Proteases/imunologia , Inibidores de Serina Proteinase/química , Inibidores de Serina Proteinase/metabolismo , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
The cytosolic appearance and propagation of bacteria cause overwhelming cellular stress responses that induce apoptosis under normal conditions. Therefore, successful bacterial colonization depends on the ability of intracellular pathogens to block apoptosis and to safeguard bacterial replicative niches. Here, we show that the cytosolic Gram-negative bacterium Shigella flexneri stalls apoptosis by inhibiting effector caspase activity. Our data identified lipopolysaccharide (LPS) as a bona fide effector caspase inhibitor that directly binds caspases by involving its O-antigen (O Ag) moiety. Bacterial strains that lacked the O Ag or failed to replicate within the cytosol were incapable of blocking apoptosis and exhibited reduced virulence in a murine model of bacterial infection. Our findings demonstrate how Shigella inhibits pro-apoptotic caspase activity, effectively delays coordinated host-cell demise and supports its intracellular propagation. Next to the recently discovered pro-inflammatory role of cytosolic LPS, our data reveal a distinct mode of LPS action that, through the disruption of the early coordinated non-lytic cell death response, ultimately supports the inflammatory breakdown of infected cells at later time points.