RESUMEN
The natural phytoalexin resveratrol (RES) has exhibited excellent anti-tumor effects on a variety of tumors including malignant melanoma. However, its specific mechanism of anti-melanoma needs to be further explored. It has been reported, that the expression of tumor suppressor gene RUNX3 was lost or substantially decreased in melanoma. Whether RES exerts its anti-tumor effect by regulating the expression of RUNX3 gene in melanoma is worthy of study. In the present study, we found the RUNX3 promoter is hypermethylated and the expression of RUNX3 mRNA and protein are absent in melanoma cells B16F10. After intervention with RES, promoter hypermethylation of RUNX3 in B16F10 cells could be significantly decreased and mRNA and protein expression of it was upregulated in a dose-dependent manner. We further investigated the effects of RES on B16F10 xenograft models. The intervention of RES and treatment of melanoma positive drug dacarbazine (DTIC) both could significantly inhibit tumor growth in xenograft mice, but only RES could upregulate the expression of RUNX3 mRNA and protein in peripheral blood and tumor tissues. Therefore, the upregulation of mRNA and protein expression of RUNX3 resulting from promoter demethylation might be one of the mechanisms of RES inhibiting melanoma. This research has revealed a novel mechanism for RES against melanoma from the epigenetic perspective, which is helpful to improve the understanding of the anti-tumor mechanism of RES and provide new insights for the treatment of melanoma.
Asunto(s)
Subunidad alfa 3 del Factor de Unión al Sitio Principal/genética , Desmetilación del ADN/efectos de los fármacos , Melanoma Experimental/tratamiento farmacológico , Melanoma Experimental/genética , Resveratrol/farmacología , Animales , Antineoplásicos Fitogénicos/farmacología , Línea Celular Tumoral , Femenino , Crecimiento/efectos de los fármacos , Xenoinjertos , Masculino , Melanoma Experimental/metabolismo , Ratones , Ratones Endogámicos C57BL , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Excessive inflammatory responses contribute to the pathogenesis and lethality of highly pathogenic human coronaviruses, but the underlying mechanism remains unclear. In this study, the N proteins of highly pathogenic human coronaviruses, including severe acute respiratory syndrome coronavirus (SARS-CoV), middle east respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), were found to bind MASP-2, a key serine protease in the lectin pathway of complement activation, resulting in excessive complement activation by potentiating MBL-dependent MASP-2 activation, and the deposition of MASP-2, C4b, activated C3 and C5b-9. Aggravated inflammatory lung injury was observed in mice infected with adenovirus expressing the N protein. Complement hyperactivation was also observed in SARS-CoV-2-infected patients. Either blocking the N protein:MASP-2 interaction, MASP-2 depletion or suppressing complement activation can significantly alleviate N protein-induced complement hyperactivation and lung injury in vitro and in vivo. Altogether, these data suggested that complement suppression may represent a novel therapeutic approach for pneumonia induced by these highly pathogenic coronaviruses.
Asunto(s)
COVID-19 , Lesión Pulmonar , Animales , COVID-19/genética , Lectina de Unión a Manosa de la Vía del Complemento/genética , Proteínas de la Nucleocápside de Coronavirus , Humanos , Inflamación/genética , Serina Proteasas Asociadas a la Proteína de Unión a la Manosa/genética , Serina Proteasas Asociadas a la Proteína de Unión a la Manosa/metabolismo , Ratones , SARS-CoV-2RESUMEN
The interaction of the solo H3K79 methyltransferase DOT1-like (DOT1L) and its regulatory factor ALL1-fused gene from chromosome 10 protein (AF10) is crucial for the transcription of developmental genes such as HOXA in acute leukemia. The octapeptide motif and leucine zipper region of AF10 is responsible for binding DOT1L and catalyzing H3K79 monomethylation to demethylation. However, the characteristics of the mechanism between DOT1L and AF10 are not clear. Here, we present the crystal structures of coiled-coil regions of DOT1L-AF10 and AF10-inhibitory peptide, demonstrating the inhibitory peptide could form a compact complex with AF10 via a different recognition pattern. Furthermore, an inhibitory peptide with structure-based optimization is identified and decreases the HOXA gene expression in a human cell line. Our studies provide an innovative pharmacologic basis for therapeutic intervention in leukemia.
Asunto(s)
Antineoplásicos/farmacología , N-Metiltransferasa de Histona-Lisina/química , Proteínas de Homeodominio/biosíntesis , Modelos Moleculares , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/química , Regulación Neoplásica de la Expresión Génica/fisiología , N-Metiltransferasa de Histona-Lisina/metabolismo , Humanos , Leucemia Mieloide Aguda/metabolismo , Conformación ProteicaRESUMEN
Dysregulated immune cell responses have been linked to the severity of coronavirus disease 2019 (COVID-19), but the specific viral factors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were currently unknown. Herein, we reveal that the Immunoglobulin-like fold ectodomain of the viral protein SARS-CoV-2 ORF7a interacts with high efficiency to CD14+ monocytes in human peripheral blood, compared to pathogenic protein SARS-CoV ORF7a. The crystal structure of SARS-CoV-2 ORF7a at 2.2 Å resolution reveals three remarkable changes on the amphipathic side of the four-stranded ß-sheet, implying a potential functional interface of the viral protein. Importantly, SARS-CoV-2 ORF7a coincubation with CD14+ monocytes ex vivo triggered a decrease in HLA-DR/DP/DQ expression levels and upregulated significant production of proinflammatory cytokines, including IL-6, IL-1ß, IL-8, and TNF-α. Our work demonstrates that SARS-CoV-2 ORF7a is an immunomodulating factor for immune cell binding and triggers dramatic inflammatory responses, providing promising therapeutic drug targets for pandemic COVID-19.
RESUMEN
Although human antibodies elicited by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein are profoundly boosted upon infection, little is known about the function of N-reactive antibodies. Herein, we isolate and profile a panel of 32 N protein-specific monoclonal antibodies (mAbs) from a quick recovery coronavirus disease-19 (COVID-19) convalescent patient who has dominant antibody responses to the SARS-CoV-2 N protein rather than to the SARS-CoV-2 spike (S) protein. The complex structure of the N protein RNA binding domain with the highest binding affinity mAb (nCoV396) reveals changes in the epitopes and antigen's allosteric regulation. Functionally, a virus-free complement hyperactivation analysis demonstrates that nCoV396 specifically compromises the N protein-induced complement hyperactivation, which is a risk factor for the morbidity and mortality of COVID-19 patients, thus laying the foundation for the identification of functional anti-N protein mAbs.
Asunto(s)
Anticuerpos Antivirales/farmacología , COVID-19/inmunología , Activación de Complemento/efectos de los fármacos , Proteínas de la Nucleocápside de Coronavirus/inmunología , SARS-CoV-2/inmunología , Regulación Alostérica , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/química , Anticuerpos Antivirales/inmunología , Afinidad de Anticuerpos , Complejo Antígeno-Anticuerpo/química , Convalecencia , Proteínas de la Nucleocápside de Coronavirus/química , Cristalografía por Rayos X , Epítopos , Humanos , Fosfoproteínas/química , Fosfoproteínas/inmunología , Conformación ProteicaRESUMEN
ORF8 is a viral immunoglobulin-like (Ig-like) domain protein encoded by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA genome. It tends to evolve rapidly and interfere with immune responses. However, the structural characteristics of various coronavirus ORF8 proteins and their subsequent effects on biological functions remain unclear. Herein, we determined the crystal structures of SARS-CoV-2 ORF8 (S84) (one of the epidemic isoforms) and the bat coronavirus RaTG13 ORF8 variant at 1.62 Å and 1.76 Å resolution, respectively. Comparison of these ORF8 proteins demonstrates that the 62-77 residues in Ig-like domain of coronavirus ORF8 adopt different conformations. Combined with mutagenesis assays, the residue Cys20 of ORF8 is responsible for forming the covalent disulfide-linked dimer in crystal packing and in vitro biochemical conditions. Furthermore, immune cell-binding assays indicate that various ORF8 (SARS-CoV-2 ORF8 (L84), ORF8 (S84), and RaTG13 ORF8) proteins have different interaction capabilities with human CD14+ monocytes in human peripheral blood. These results provide new insights into the specific characteristics of various coronavirus ORF8 and suggest that ORF8 variants may influence disease-related immune responses.
Asunto(s)
COVID-19/inmunología , Quirópteros/inmunología , Inmunidad/inmunología , Dominios de Inmunoglobulinas/inmunología , Proteínas Virales/inmunología , Animales , Sitios de Unión/genética , COVID-19/virología , Células Cultivadas , Quirópteros/genética , Quirópteros/metabolismo , Cristalografía por Rayos X , Humanos , Inmunidad/genética , Dominios de Inmunoglobulinas/genética , Receptores de Lipopolisacáridos/inmunología , Receptores de Lipopolisacáridos/metabolismo , Modelos Moleculares , Monocitos/inmunología , Monocitos/metabolismo , Mutación , Unión Proteica , Especificidad de la Especie , Proteínas Virales/clasificación , Proteínas Virales/genéticaRESUMEN
The emerging new lineages of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have marked a new phase of coronavirus disease 2019 (COVID-19). Understanding the recognition mechanisms of potent neutralizing monoclonal antibodies (NAbs) against the spike protein is pivotal for developing new vaccines and antibody drugs. Here, we isolated several monoclonal antibodies (MAbs) against the SARS-CoV-2 spike protein receptor-binding domain (S-RBD) from the B cell receptor repertoires of a SARS-CoV-2 convalescent. Among these MAbs, the antibody nCoV617 demonstrates the most potent neutralizing activity against authentic SARS-CoV-2 infection, as well as prophylactic and therapeutic efficacies against the human angiotensin-converting enzyme 2 (ACE2) transgenic mouse model in vivo. The crystal structure of S-RBD in complex with nCoV617 reveals that nCoV617 mainly binds to the back of the "ridge" of RBD and shares limited binding residues with ACE2. Under the background of the S-trimer model, it potentially binds to both "up" and "down" conformations of S-RBD. In vitro mutagenesis assays show that mutant residues found in the emerging new lineage B.1.1.7 of SARS-CoV-2 do not affect nCoV617 binding to the S-RBD. These results provide a new human-sourced neutralizing antibody against the S-RBD and assist vaccine development. IMPORTANCE COVID-19 is a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The COVID-19 pandemic has posed a serious threat to global health and the economy, so it is necessary to find safe and effective antibody drugs and treatments. The receptor-binding domain (RBD) in the SARS-CoV-2 spike protein is responsible for binding to the angiotensin-converting enzyme 2 (ACE2) receptor. It contains a variety of dominant neutralizing epitopes and is an important antigen for the development of new coronavirus antibodies. The significance of our research lies in the determination of new epitopes, the discovery of antibodies against RBD, and the evaluation of the antibodies' neutralizing effect. The identified antibodies here may be drug candidates for the development of clinical interventions for SARS-CoV-2.
Asunto(s)
Anticuerpos Neutralizantes/uso terapéutico , Anticuerpos Antivirales/uso terapéutico , COVID-19/terapia , SARS-CoV-2/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , Enzima Convertidora de Angiotensina 2/antagonistas & inhibidores , Enzima Convertidora de Angiotensina 2/genética , Enzima Convertidora de Angiotensina 2/inmunología , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/uso terapéutico , Anticuerpos Neutralizantes/inmunología , Anticuerpos Neutralizantes/metabolismo , Anticuerpos Antivirales/inmunología , Anticuerpos Antivirales/metabolismo , Sitios de Unión/inmunología , Vacunas contra la COVID-19/inmunología , Cristalografía por Rayos X , Modelos Animales de Enfermedad , Femenino , Humanos , Inmunización Pasiva/métodos , Inmunoglobulina G/sangre , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Dominios y Motivos de Interacción de Proteínas/inmunología , Carga Viral/efectos de los fármacos , Sueroterapia para COVID-19RESUMEN
Coronavirus disease 2019 (COVID-19) has caused massive disruptions to society and the economy, and the transcriptional regulatory mechanisms behind the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are poorly understood. Herein, we determined the crystal structure of the SARS-CoV-2 nucleocapsid protein C-terminal domain (CTD) at a resolution of 2.0 Å, and demonstrated that the CTD has a comparable distinct electrostatic potential surface to equivalent domains of other reported CoVs, suggesting that the CTD has novel roles in viral RNA binding and transcriptional regulation. Further in vitro biochemical assays demonstrated that the viral genomic intergenic transcriptional regulatory sequences (TRSs) interact with the SARS-CoV-2 nucleocapsid protein CTD with a flanking region. The unpaired adeno dinucleotide in the TRS stem-loop structure is a major determining factor for their interactions. Taken together, these results suggested that the nucleocapsid protein CTD is responsible for the discontinuous viral transcription mechanism by recognizing the different patterns of viral TRS during transcription.
RESUMEN
The outbreak of coronavirus disease (COVID-19) caused by SARS-CoV-2 virus continually lead to worldwide human infections and deaths. Currently, there is no specific viral protein-targeted therapeutics. Viral nucleocapsid protein is a potential antiviral drug target, serving multiple critical functions during the viral life cycle. However, the structural information of SARS-CoV-2 nucleocapsid protein remains unclear. Herein, we have determined the 2.7 Å crystal structure of the N-terminal RNA binding domain of SARS-CoV-2 nucleocapsid protein. Although the overall structure is similar as other reported coronavirus nucleocapsid protein N-terminal domain, the surface electrostatic potential characteristics between them are distinct. Further comparison with mild virus type HCoV-OC43 equivalent domain demonstrates a unique potential RNA binding pocket alongside the ß-sheet core. Complemented by in vitro binding studies, our data provide several atomic resolution features of SARS-CoV-2 nucleocapsid protein N-terminal domain, guiding the design of novel antiviral agents specific targeting to SARS-CoV-2.
RESUMEN
Mitofusin-2 (MFN2) is a dynamin-like GTPase that plays a central role in regulating mitochondrial fusion and cell metabolism. Mutations in MFN2 cause the neurodegenerative disease Charcot-Marie-Tooth type 2A (CMT2A). The molecular basis underlying the physiological and pathological relevance of MFN2 is unclear. Here, we present crystal structures of truncated human MFN2 in different nucleotide-loading states. Unlike other dynamin superfamily members including MFN1, MFN2 forms sustained dimers even after GTP hydrolysis via the GTPase domain (G) interface, which accounts for its high membrane-tethering efficiency. The biochemical discrepancy between human MFN2 and MFN1 largely derives from a primate-only single amino acid variance. MFN2 and MFN1 can form heterodimers via the G interface in a nucleotide-dependent manner. CMT2A-related mutations, mapping to different functional zones of MFN2, lead to changes in GTP hydrolysis and homo/hetero-association ability. Our study provides fundamental insight into how mitofusins mediate mitochondrial fusion and the ways their disruptions cause disease.