RESUMEN
Plants continuously form new organs in different developmental contexts in response to environmental cues. Underground lateral roots initiate from prepatterned cells in the main root, but cells can also bypass the root-shoot trajectory separation and generate shoot-borne roots through an unknown mechanism. We mapped tomato (Solanum lycopersicum) shoot-borne root development at single-cell resolution and showed that these roots initiate from phloem-associated cells through a unique transition state. This state requires the activity of a transcription factor that we named SHOOTBORNE ROOTLESS (SBRL). Evolutionary analysis reveals that SBRL's function and cis regulation are conserved in angiosperms and that it arose as an ancient duplication, with paralogs controlling wound-induced and lateral root initiation. We propose that the activation of a common transition state by context-specific regulators underlies the plasticity of plant root systems.
Asunto(s)
Genes de Plantas , Raíces de Plantas/crecimiento & desarrollo , Brotes de la Planta/crecimiento & desarrollo , Solanum lycopersicum/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas , Sitios Genéticos , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Magnoliopsida/genética , Magnoliopsida/crecimiento & desarrollo , Magnoliopsida/metabolismo , Meristema/crecimiento & desarrollo , Meristema/metabolismo , Proteínas de Plantas/genética , Raíces de Plantas/citología , Raíces de Plantas/metabolismo , Brotes de la Planta/citología , Brotes de la Planta/metabolismo , RNA-Seq , Análisis de la Célula Individual , Transcripción GenéticaRESUMEN
Hematopoietic stem and progenitor cells (HSPCs) are a small population of undifferentiated cells that have the capacity for self-renewal and differentiate into all blood cell lineages. These cells are the most useful cells for clinical transplantations and for regenerative medicine. So far, it has not been possible to expand adult hematopoietic stem cells (HSCs) without losing their self-renewal properties. CD74 is a cell surface receptor for the cytokine macrophage migration inhibitory factor (MIF), and its mRNA is known to be expressed in HSCs. Here, we demonstrate that mice lacking CD74 exhibit an accumulation of HSCs in the bone marrow (BM) due to their increased potential to repopulate and compete for BM niches. Our results suggest that CD74 regulates the maintenance of the HSCs and CD18 expression. Its absence leads to induced survival of these cells and accumulation of quiescent and proliferating cells. Furthermore, in in vitro experiments, blocking of CD74 elevated the numbers of HSPCs. Thus, we suggest that blocking CD74 could lead to improved clinical insight into BM transplant protocols, enabling improved engraftment.
Asunto(s)
Antígenos de Diferenciación de Linfocitos B/genética , Antígenos de Diferenciación de Linfocitos B/metabolismo , Células Madre Hematopoyéticas/metabolismo , Antígenos de Histocompatibilidad Clase II/genética , Antígenos de Histocompatibilidad Clase II/metabolismo , Adulto , Animales , Células de la Médula Ósea/metabolismo , Trasplante de Médula Ósea/métodos , Linaje de la Célula , Femenino , Voluntarios Sanos , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/fisiología , Humanos , Oxidorreductasas Intramoleculares/metabolismo , Factores Inhibidores de la Migración de Macrófagos/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Transducción de SeñalRESUMEN
The root meristem can regenerate following removal of its stem-cell niche by recruitment of remnant cells from the stump. Regeneration is initiated by rapid accumulation of auxin near the injury site but the source of this auxin is unknown. Here, we show that auxin accumulation arises from the activity of multiple auxin biosynthetic sources that are newly specified near the cut site and that their continuous activity is required for the regeneration process. Auxin synthesis is highly localized while PIN-mediated transport is dispensable for auxin accumulation and tip regeneration. Roots lacking the activity of the regeneration competence factor ERF115, or that are dissected at a zone of low regeneration potential, fail to activate local auxin sources. Remarkably, restoring auxin supply is sufficient to confer regeneration capacity to these recalcitrant tissues. We suggest that regeneration competence relies on the ability to specify new local auxin sources in a precise temporal pattern.
Asunto(s)
Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/fisiología , Raíces de Plantas/fisiología , Arabidopsis/metabolismo , Arabidopsis/fisiología , Meristema/metabolismo , Meristema/fisiología , Reguladores del Crecimiento de las Plantas/metabolismo , Regeneración/fisiologíaRESUMEN
CD74 is a cell-surface receptor for the cytokine macrophage migration inhibitory factor. Macrophage migration inhibitory factor binding to CD74 induces its intramembrane cleavage and the release of its cytosolic intracellular domain (CD74-ICD), which regulates cell survival. In the present study, we characterized the transcriptional activity of CD74-ICD in chronic lymphocytic B cells. We show that following CD74 activation, CD74-ICD interacts with the transcription factors RUNX (Runt related transcription factor) and NF-κB and binds to proximal and distal regulatory sites enriched for genes involved in apoptosis, immune response, and cell migration. This process leads to regulation of expression of these genes. Our results suggest that identifying targets of CD74 will help in understanding of essential pathways regulating B-cell survival in health and disease.
