RESUMO
Non-structural protein 1 (NS1) is an important virulence factor encoded by influenza A virus. NS1 can interact with a variety of host cell proteins to interfere with the host innate immune response and to promote effective viral replication. Our previous work has shown that only the effector domain of NS1 (amino acid residues 74-230/237) is sufficient to interact with nucleolar and coiled-body phosphoprotein 1 (NOLC1). To investigate the exact region of NS1 that interacts with NOLC1, we used only the effector domain of NS1 and constructed various mutants having different deletions, and then tested their ability to interact with NOLC1 via pull-down assay. Only the mutant containing amino acid residues 104-200 showed positive interaction with NOLC1. To further determine the key amino acids of the NS1 effector domain which are crucial for interaction with NOLC1, several mutants containing a single amino acid substitution were made and their interaction with NOLC1 was tested. Only the mutant D120A or R195A showed reduced binding with NOLC1, suggesting that D120 and R195 were crucial to the binding of NS1 to NOLC1. This study lays the foundation for further research aiming at furthering our understanding of the interaction between NS1 and host cells.
Assuntos
Virus da Influenza A Subtipo H5N1/metabolismo , Influenza Humana/metabolismo , Proteínas Nucleares/metabolismo , Fosfoproteínas/metabolismo , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/metabolismo , Sequência de Aminoácidos , Animais , Células COS , Chlorocebus aethiops , Humanos , Virus da Influenza A Subtipo H5N1/química , Virus da Influenza A Subtipo H5N1/genética , Influenza Humana/genética , Influenza Humana/virologia , Dados de Sequência Molecular , Proteínas Nucleares/genética , Fosfoproteínas/genética , Ligação Proteica , Estrutura Terciária de Proteína , Alinhamento de Sequência , Proteínas não Estruturais Virais/genética , VirulênciaRESUMO
Anaplastic thyroid carcinoma (ATC) has a 100% disease-specific mortality rate. The JAK1/2-STAT3 pathway presents a promising target for treating hematologic and solid tumors. However, it is unknown whether the JAK1/2-STAT3 pathway is activated in ATC, and the anti-cancer effects and the mechanism of action of its inhibitor, ruxolitinib (Ruxo, a clinical JAK1/2 inhibitor), remain elusive. Our data indicated that the JAK1/2-STAT3 signaling pathway is significantly upregulated in ATC tumor tissues than in normal thyroid and papillary thyroid cancer tissues. Apoptosis and GSDME-pyroptosis were observed in ATC cells following the in vitro and in vivo administration of Ruxo. Mechanistically, Ruxo suppresses the phosphorylation of STAT3, resulting in the repression of DRP1 transactivation and causing mitochondrial fission deficiency. This deficiency is essential for activating caspase 9/3-dependent apoptosis and GSDME-mediated pyroptosis within ATC cells. In conclusion, our findings indicate DRP1 is directly regulated and transactivated by STAT3; this exhibits a novel and crucial aspect of JAK1/2-STAT3 on the regulation of mitochondrial dynamics. In ATC, the transcriptional inhibition of DRP1 by Ruxo hampered mitochondrial division and triggered apoptosis and GSDME-pyroptosis through caspase 9/3-dependent mechanisms. These results provide compelling evidence for the potential therapeutic effectiveness of Ruxo in treating ATC.