RESUMEN
Tactical disruption of protein synthesis is an attractive therapeutic strategy, with the first-in-class eIF4A-targeting compound zotatifin in clinical evaluation for cancer and COVID-19. The full cellular impact and mechanisms of these potent molecules are undefined at a proteomic level. Here, we report mass spectrometry analysis of translational reprogramming by rocaglates, cap-dependent initiation disruptors that include zotatifin. We find effects to be far more complex than simple "translational inhibition" as currently defined. Translatome analysis by TMT-pSILAC (tandem mass tag-pulse stable isotope labeling with amino acids in cell culture mass spectrometry) reveals myriad upregulated proteins that drive hitherto unrecognized cytotoxic mechanisms, including GEF-H1-mediated anti-survival RHOA/JNK activation. Surprisingly, these responses are not replicated by eIF4A silencing, indicating a broader translational adaptation than currently understood. Translation machinery analysis by MATRIX (mass spectrometry analysis of active translation factors using ribosome density fractionation and isotopic labeling experiments) identifies rocaglate-specific dependence on specific translation factors including eEF1ε1 that drive translatome remodeling. Our proteome-level interrogation reveals that the complete cellular response to these historical "translation inhibitors" is mediated by comprehensive translational landscape remodeling.
Asunto(s)
Biosíntesis de Proteínas/efectos de los fármacos , Inhibidores de la Síntesis de la Proteína/farmacología , Animales , Benzofuranos/farmacología , Línea Celular Tumoral , Factor 4A Eucariótico de Iniciación/efectos de los fármacos , Factor 4A Eucariótico de Iniciación/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos NOD , Cultivo Primario de Células , Biosíntesis de Proteínas/fisiología , Proteómica/métodos , Ribosomas/metabolismo , Transcriptoma/efectos de los fármacos , Transcriptoma/genética , Triterpenos/farmacologíaRESUMEN
Flavaglines are cyclopenta[b]benzofurans found in plants of the genus Aglaia, several species of which are used in traditional Chinese medicine. These compounds target the initiation factor of translation eIF4A and the scaffold proteins prohibitins-1 and 2 (PHB1/2) to exert various pharmacological activities, including antiviral effects against several types of viruses, including coronaviruses. This review is focused on the antiviral effects of flavaglines and their therapeutic potential against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Asunto(s)
Aglaia/química , Antivirales/uso terapéutico , Productos Biológicos/uso terapéutico , Infecciones por Coronavirus/tratamiento farmacológico , Factor 4A Eucariótico de Iniciación/genética , Neumonía Viral/tratamiento farmacológico , Proteínas Represoras/genética , Animales , COVID-19 , Factor 4A Eucariótico de Iniciación/efectos de los fármacos , Humanos , Medicina Tradicional China , Pandemias , Prohibitinas , Proteínas Represoras/efectos de los fármacosRESUMEN
Flavaglines are complex natural products that are found in several medicinal plants of Southeast Asia in the genus Aglaia; these compounds have shown exceptional anticancer and cytoprotective activities. This review describes the significance of flavaglines as a new class of pharmacological agents and presents recent developments in their synthesis, structure-activity relationships, identification of their molecular targets and modes of action. Flavaglines display a unique profile of anticancer activities that are mediated by two classes of unrelated proteins: prohibitins and the translation initiation factor eIF4A. The identification of these molecular targets is expected to accelerate advancement toward clinical studies. The selectivity of cytotoxicity towards cancer cells has been shown to be due to an inhibition of the transcription factor HSF1 and an upregulation of the tumor suppressor TXNIP. In addition, flavaglines display potent anti-inflammatory, cardioprotective and neuroprotective activities; however, the mechanisms underlying these activities are yet to be elucidated.
Asunto(s)
Antineoplásicos/farmacología , Productos Biológicos/farmacología , Factor 4A Eucariótico de Iniciación/efectos de los fármacos , Proteínas Represoras/antagonistas & inhibidores , Antineoplásicos/química , Productos Biológicos/química , Humanos , Prohibitinas , Relación Estructura-ActividadRESUMEN
A recent publication revealing that the cytotoxic marine natural product pateamine A targets eukaryotic initiation factor eIF4A continues a story with lessons for both chemists and biologists, that is, the significance of natural products, the importance of synthetic organic chemistry, the small molecule regulation of eukaryotic translation machinery, and possibly a new approach to cancer chemotherapy.
Asunto(s)
Compuestos Epoxi/uso terapéutico , Factor 4A Eucariótico de Iniciación/antagonistas & inhibidores , Macrólidos/uso terapéutico , Tiazoles/uso terapéutico , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Compuestos Epoxi/síntesis química , Compuestos Epoxi/química , Compuestos Epoxi/farmacología , Factor 4A Eucariótico de Iniciación/efectos de los fármacos , Factor 4A Eucariótico de Iniciación/genética , Macrólidos/síntesis química , Macrólidos/química , Macrólidos/farmacología , Modelos Genéticos , Modelos Moleculares , Biosíntesis de Proteínas/efectos de los fármacos , ARN Mensajero/genética , Tiazoles/síntesis química , Tiazoles/química , Tiazoles/farmacologíaRESUMEN
Eukaryotic initiation factor 4A (eIF4A) is a member of the DEAD-box family of putative RNA helicases whose members are involved in many aspects of RNA metabolism. eIF4A is thought to facilitate binding of 43S preinitiation complexes to mRNAs by unwinding secondary structures present in the 5' untranslated region. Pateamine A, a small-molecule inhibitor of translation initiation, acts in an unusual manner by stimulating eIF4A activity. Herein, we report the elucidation of pateamine's mode of action. We demonstrate that Pateamine A is a chemical inducer of dimerization that forces an engagement between eIF4A and RNA and prevents eIF4A from participating in the ribosome-recruitment step of translation initiation.
Asunto(s)
Compuestos Epoxi/farmacología , Factor 4A Eucariótico de Iniciación/efectos de los fármacos , Factor 4A Eucariótico de Iniciación/metabolismo , Macrólidos/farmacología , Biosíntesis de Proteínas/fisiología , ARN/metabolismo , Tiazoles/farmacología , Dimerización , Factor 4G Eucariótico de Iniciación/efectos de los fármacos , Factor 4G Eucariótico de Iniciación/metabolismo , Humanos , Células Jurkat , Complejos Multiproteicos/efectos de los fármacos , Complejos Multiproteicos/metabolismo , Unión Proteica/fisiología , Biosíntesis de Proteínas/efectos de los fármacosRESUMEN
Translation initiation in eukaryotes is accomplished through the coordinated and orderly action of a large number of proteins, including the eIF4 initiation factors. Herein, we report that pateamine A (PatA), a potent antiproliferative and proapoptotic marine natural product, inhibits cap-dependent eukaryotic translation initiation. PatA bound to and enhanced the intrinsic enzymatic activities of eIF4A, yet it inhibited eIF4A-eIF4G association and promoted the formation of a stable ternary complex between eIF4A and eIF4B. These changes in eIF4A affinity for its partner proteins upon binding to PatA caused the stalling of initiation complexes on mRNA in vitro and induced stress granule formation in vivo. These results suggest that PatA will be a valuable molecular probe for future studies of eukaryotic translation initiation and may serve as a lead compound for the development of anticancer agents.