ABSTRACT
The aim of this study was to evaluate the effect of everolimus, a mammalian target of rapamycin (mTOR) inhibitor, on red blood cell parameters in the context of iron homeostasis in patients with tuberous sclerosis complex (TSC) and evaluate its effect on cell size in vitro. Everolimus has a significant impact on red blood cell parameters in patients with TSC. The most common alteration was microcytosis. The mean MCV value decreased by 9.2%, 12%, and 11.8% after 3, 6, and 12 months of everolimus treatment. The iron level declined during the first 3 months, and human soluble transferrin receptor concentration increased during 6 months of therapy. The size of K562 cells decreased when cultured in the presence of 5 µM everolimus by approximately 8%. The addition of hemin to the cell culture with 5 µM everolimus did not prevent any decrease in cell size. The stage of erythroid maturation did not affect the response to everolimus. Our results showed that the mTOR inhibitor everolimus caused red blood cell microcytosis in vivo and in vitro. This effect is not clearly related to a deficit of iron and erythroid maturation. This observation confirms that mTOR signaling plays a complex role in the control of cell size.
Subject(s)
Cell Size/drug effects , Erythrocytes/drug effects , Erythrocytes/pathology , Protein Kinase Inhibitors/pharmacology , TOR Serine-Threonine Kinases/antagonists & inhibitors , Adolescent , Biomarkers , Cell Differentiation/drug effects , Cell Line , Child , Child, Preschool , Erythrocyte Indices , Erythrocytes/metabolism , Everolimus/administration & dosage , Everolimus/adverse effects , Everolimus/pharmacology , Flow Cytometry , Humans , Iron/metabolism , K562 Cells , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/adverse effectsABSTRACT
In December 2019, the first cases of infection with a novel coronavirus, SARS-CoV-2, were diagnosed. Currently, there is no effective antiviral treatment for COVID-19. To address this emerging problem, we focused on the SARS-CoV-2 main protease that constitutes one of the most attractive antiviral drug targets. We have synthesized a combinatorial library of fluorogenic substrates with glutamine in the P1 position. We used it to determine the substrate preferences of the SARS-CoV and SARS-CoV-2 main proteases. On the basis of these findings, we designed and synthesized a potent SARS-CoV-2 inhibitor (Ac-Abu-DTyr-Leu-Gln-VS, half-maximal effective concentration of 3.7 µM) and two activity-based probes, for one of which we determined the crystal structure of its complex with the SARS-CoV-2 Mpro. We visualized active SARS-CoV-2 Mpro in nasopharyngeal epithelial cells of patients suffering from COVID-19 infection. The results of our work provide a structural framework for the design of inhibitors as antiviral agents and/or diagnostic tests.