RESUMEN
Axon loss underlies symptom onset and progression in many neurodegenerative disorders. Axon degeneration in injury and disease is promoted by activation of the NAD-consuming enzyme SARM1. Here, we report a novel activator of SARM1, a metabolite of the pesticide and neurotoxin vacor. Removal of SARM1 completely rescues mouse neurons from vacor-induced neuron and axon death in vitro and in vivo. We present the crystal structure of the Drosophila SARM1 regulatory domain complexed with this activator, the vacor metabolite VMN, which as the most potent activator yet known is likely to support drug development for human SARM1 and NMNAT2 disorders. This study indicates the mechanism of neurotoxicity and pesticide action by vacor, raises important questions about other pyridines in wider use today, provides important new tools for drug discovery, and demonstrates that removing SARM1 can robustly block programmed axon death induced by toxicity as well as genetic mutation.
Asunto(s)
Proteínas del Dominio Armadillo/genética , Axones/patología , Proteínas del Citoesqueleto/genética , Degeneración Nerviosa/fisiopatología , Neurotoxinas/farmacología , Compuestos de Fenilurea/farmacología , Animales , Proteínas del Dominio Armadillo/metabolismo , Axones/efectos de los fármacos , Proteínas del Citoesqueleto/metabolismo , Femenino , Masculino , Ratones , Degeneración Nerviosa/inducido químicamente , Rodenticidas/farmacologíaRESUMEN
Communication between the inner cell mass (ICM) and the trophoblast layer of the blastocyst is known to occur, but its functional consequences on early developmental events is unclear. Here we demonstrate that embryonic stem (ES) cells derived from the ICM generate and shed microvesicles (MVs), a major class of extracellular vesicles (EVs), which influence trophoblast behaviour during the implantation process. The MV cargo proteins laminin and fibronectin interact with integrins along the surfaces of the trophoblasts, triggering the activation of two signalling kinases, JNK and FAK, and stimulating trophoblast migration. We further show that injecting MVs isolated from ES cells into blastocysts results in an increase in their implantation efficiency. Thus, these findings highlight a unique mechanism by which ES cells communicate with trophoblasts within the blastocyst to increase their ability to migrate into the uterus, thereby promoting one of the earliest and most important steps during pregnancy.
Asunto(s)
Comunicación Celular , Micropartículas Derivadas de Células/metabolismo , Implantación del Embrión , Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Espacio Extracelular/metabolismo , Animales , Blastocisto/citología , Blastocisto/metabolismo , Movimiento Celular , Micropartículas Derivadas de Células/ultraestructura , Células Madre Embrionarias/ultraestructura , Fibronectinas/metabolismo , Laminina/metabolismo , Ratones , Modelos Biológicos , Fenotipo , Trofoblastos/citologíaRESUMEN
The generation and shedding of extracellular vesicles (EVs), including exosomes and microvesicles (MVs), by cells has emerged as a form of intercellular communication with important roles in several physiological processes and diseases such as cancer. These membrane-enclosed packets can transfer specific proteins, RNA transcripts, microRNAs, and even DNA to target cells, thereby altering their function. Despite the exponential growth of the EV field, a great deal remains unclear about the mechanisms that regulate exosome and MV biogenesis, as well as about how to isolate different classes of EVs and how to best take advantage of them for clinical applications.