RESUMEN
Cells respond to perturbations such as inflammation by sensing changes in metabolite levels. Especially prominent is arginine, which has known connections to the inflammatory response. Aminoacyl-tRNA synthetases, enzymes that catalyse the first step of protein synthesis, can also mediate cell signalling. Here we show that depletion of arginine during inflammation decreased levels of nuclear-localized arginyl-tRNA synthetase (ArgRS). Surprisingly, we found that nuclear ArgRS interacts and co-localizes with serine/arginine repetitive matrix protein 2 (SRRM2), a spliceosomal and nuclear speckle protein, and that decreased levels of nuclear ArgRS correlated with changes in condensate-like nuclear trafficking of SRRM2 and splice-site usage in certain genes. These splice-site usage changes cumulated in the synthesis of different protein isoforms that altered cellular metabolism and peptide presentation to immune cells. Our findings uncover a mechanism whereby an aminoacyl-tRNA synthetase cognate to a key amino acid that is metabolically controlled during inflammation modulates the splicing machinery.
Asunto(s)
Aminoacil-ARNt Sintetasas , Arginino-ARNt Ligasa , Aminoácidos/metabolismo , Aminoacil-ARNt Sintetasas/genética , Aminoacil-ARNt Sintetasas/metabolismo , Arginina/química , Arginina/genética , Arginina/metabolismo , Arginino-ARNt Ligasa/química , Arginino-ARNt Ligasa/genética , Arginino-ARNt Ligasa/metabolismo , Empalme del ARN , Proteínas de Unión al ARN/metabolismoRESUMEN
While it is now appreciated that certain long noncoding RNAs (lncRNAs) have important functions in cell biology, relatively few have been shown to regulate development in vivo, particularly with genetic strategies that establish cis versus trans mechanisms. Pnky is a nuclear-enriched lncRNA that is transcribed divergently from the neighboring proneural transcription factor Pou3f2. Here, we show that conditional deletion of Pnky from the developing cortex regulates the production of projection neurons from neural stem cells (NSCs) in a cell-autonomous manner, altering postnatal cortical lamination. Surprisingly, Pou3f2 expression is not disrupted by deletion of the entire Pnky gene. Moreover, expression of Pnky from a BAC transgene rescues the differential gene expression and increased neurogenesis of Pnky-knockout NSCs, as well as the developmental phenotypes of Pnky-deletion in vivo. Thus, despite being transcribed divergently from a key developmental transcription factor, the lncRNA Pnky regulates development in trans.
Asunto(s)
Corteza Cerebral/embriología , Células-Madre Neurales/metabolismo , ARN Largo no Codificante/genética , Animales , Encéfalo/metabolismo , Corteza Cerebral/metabolismo , Femenino , Interneuronas/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas del Tejido Nervioso/genética , Neurogénesis/genética , Neuronas/metabolismo , Factores del Dominio POU/genética , ARN Largo no Codificante/metabolismo , Transactivadores/genética , Transactivadores/metabolismo , Factores de Transcripción/metabolismoRESUMEN
Phagocytosis, a critical early event in the microbicidal response of neutrophils, is now appreciated to serve multiple functions in a variety of cell types. Professional phagocytes play a central role in innate immunity by eliminating pathogenic bacteria, fungi and malignant cells, and contribute to adaptive immunity by presenting antigens to lymphocytes. In addition, phagocytes play a part in tissue remodeling and maintain overall homeostasis by disposing of apoptotic cells, a task shared by non-professional phagocytes, often of epithelial origin. This functional versatility is supported by a vast array of receptors capable of recognizing a striking variety of foreign and endogenous ligands. Here we present an abbreviated overview of the different types of phagocytes, their varied modes of signaling and particle engulfment, and the multiple physiological roles of phagocytosis.