RESUMO
The SARS-CoV-2 coronavirus encodes an essential papain-like protease domain as part of its non-structural protein (nsp)-3, namely SARS2 PLpro, that cleaves the viral polyprotein, but also removes ubiquitin-like ISG15 protein modifications as well as, with lower activity, Lys48-linked polyubiquitin. Structures of PLpro bound to ubiquitin and ISG15 reveal that the S1 ubiquitin-binding site is responsible for high ISG15 activity, while the S2 binding site provides Lys48 chain specificity and cleavage efficiency. To identify PLpro inhibitors in a repurposing approach, screening of 3,727 unique approved drugs and clinical compounds against SARS2 PLpro identified no compounds that inhibited PLpro consistently or that could be validated in counterscreens. More promisingly, non-covalent small molecule SARS PLpro inhibitors also target SARS2 PLpro, prevent self-processing of nsp3 in cells and display high potency and excellent antiviral activity in a SARS-CoV-2 infection model.
Assuntos
Antivirais/farmacologia , Proteases 3C de Coronavírus/antagonistas & inibidores , Proteases 3C de Coronavírus/metabolismo , SARS-CoV-2/metabolismo , Ubiquitina/metabolismo , Animais , Sítios de Ligação , Chlorocebus aethiops , Proteases 3C de Coronavírus/química , Proteases 3C de Coronavírus/genética , Cristalografia por Raios X , Citocinas/genética , Avaliação Pré-Clínica de Medicamentos/métodos , Reposicionamento de Medicamentos , Polarização de Fluorescência , Células HEK293 , Humanos , Cinética , Modelos Moleculares , Inibidores de Proteases/farmacologia , Conformação Proteica , SARS-CoV-2/química , SARS-CoV-2/genética , Ubiquitinas/genética , Células VeroRESUMO
Myeloid cell leukemia-1 (MCL-1) is a prosurvival B-cell lymphoma 2 (BCL-2) family member required for the sustained growth of many cancers. Recently, a highly specific MCL-1 inhibitor, S63845, showing sixfold higher affinity to human compared with mouse MCL-1, has been described. To accurately test efficacy and tolerability of this BH3-mimetic (BH3-only protein mimetic) drug in preclinical cancer models, we developed a humanized Mcl-1 (huMcl-1) mouse strain in which MCL-1 was replaced with its human homolog. huMcl-1 mice are phenotypically indistinguishable from wild-type mice but are more sensitive to the MCL-1 inhibitor S63845. Importantly, nontransformed cells and lymphomas from huMcl-1;Eµ-Myc mice are more sensitive to S63845 in vitro than their control counterparts. When huMcl-1;Eµ-Myc lymphoma cells were transplanted into huMcl-1 mice, treatment with S63845 alone or alongside cyclophosphamide led to long-term remission in â¼60% or almost 100% of mice, respectively. These results demonstrate the potential of our huMcl-1 mouse model for testing MCL-1 inhibitors, allowing precise predictions of efficacy and tolerability for clinical translation.