RESUMEN
The dorsal and ventral human telencephalons contain different neuronal subtypes, including glutamatergic, GABAergic, and cholinergic neurons, and how these neurons are generated during early development is not well understood. Using scRNA-seq and stringent validations, we reveal here a developmental roadmap for human telencephalic neurons. Both dorsal and ventral telencephalic radial glial cells (RGs) differentiate into neurons via dividing intermediate progenitor cells (IPCs_div) and early postmitotic neuroblasts (eNBs). The transcription factor ASCL1 plays a key role in promoting fate transition from RGs to IPCs_div in both regions. RGs from the regionalized neuroectoderm show heterogeneity, with restricted glutamatergic, GABAergic, and cholinergic differentiation potencies. During neurogenesis, IPCs_div gradually exit the cell cycle and branch into sister eNBs to generate distinct neuronal subtypes. Our findings highlight a general RGs-IPCs_div-eNBs developmental scheme for human telencephalic progenitors and support that the major neuronal fates of human telencephalon are predetermined during dorsoventral regionalization with neuronal diversity being further shaped during neurogenesis and neural circuit integration.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Linaje de la Célula/genética , Regulación del Desarrollo de la Expresión Génica , Neurogénesis/genética , Neuronas/metabolismo , Telencéfalo/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Ciclo Celular/genética , Diferenciación Celular , Colina/metabolismo , Proteína Doblecortina/genética , Proteína Doblecortina/metabolismo , Feto , Ontología de Genes , Glutamato Descarboxilasa/genética , Glutamato Descarboxilasa/metabolismo , Ácido Glutámico/metabolismo , Humanos , Proteínas con Homeodominio LIM/genética , Proteínas con Homeodominio LIM/metabolismo , Anotación de Secuencia Molecular , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Células-Madre Neurales/citología , Células-Madre Neurales/metabolismo , Neuroglía/citología , Neuroglía/metabolismo , Neuronas/clasificación , Neuronas/citología , Factores de Transcripción SOXC/genética , Factores de Transcripción SOXC/metabolismo , Transducción de Señal , Estatmina/genética , Estatmina/metabolismo , Telencéfalo/citología , Telencéfalo/crecimiento & desarrollo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Human doublecortin (DCX) mutations are associated with severe brain malformations leading to aberrant neuron positioning (heterotopia), intellectual disability and epilepsy. DCX is a microtubule-associated protein which plays a key role during neurodevelopment in neuronal migration and differentiation. Dcx knockout (KO) mice show disorganized hippocampal pyramidal neurons. The CA2/CA3 pyramidal cell layer is present as two abnormal layers and disorganized CA3 KO pyramidal neurons are also more excitable than wild-type (WT) cells. To further identify abnormalities, we characterized Dcx KO hippocampal neurons at subcellular, molecular and ultrastructural levels. Severe defects were observed in mitochondria, affecting number and distribution. Also, the Golgi apparatus was visibly abnormal, increased in volume and abnormally organized. Transcriptome analyses from laser microdissected hippocampal tissue at postnatal day 60 (P60) highlighted organelle abnormalities. Ultrastructural studies of CA3 cells performed in P60 (young adult) and > 9 months (mature) tissue showed that organelle defects are persistent throughout life. Locomotor activity and fear memory of young and mature adults were also abnormal: Dcx KO mice consistently performed less well than WT littermates, with defects becoming more severe with age. Thus, we show that disruption of a neurodevelopmentally-regulated gene can lead to permanent organelle anomalies contributing to abnormal adult behavior.
Asunto(s)
Proteína Doblecortina/genética , Neuropéptidos , Animales , Proteínas de Dominio Doblecortina , Aparato de Golgi , Hipocampo/metabolismo , Ratones , Ratones Noqueados , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Mitocondrias/metabolismo , Mutación , Neuropéptidos/genética , Neuropéptidos/metabolismo , Células Piramidales/metabolismoRESUMEN
Glioblastoma (GBM) remains the leading cause of cancer-related deaths with the lowest five-year survival rates among all of the human cancers. Multiple factors contribute to its poor outcome, including intratumor heterogeneity, along with migratory and invasive capacities of tumour cells. Over the last several years Doublecortin (DCX) has been one of the debatable factors influencing GBM cells' migration. To resolve DCX's ambiguous role in GBM cells' migration, we set to analyse the expression patterns of DCX along with Nestin (NES) and Oligodendrocyte lineage transcription factor 2 (OLIG2) in 17 cases of GBM, using immunohistochemistry, followed by an analysis of single-cell RNA-seq data. Our results showed that only a small subset of DCX positive (DCX+) cells was present in the tumour. Moreover, no particular pattern emerged when analysing DCX+ cells relative position to the tumour margin. By looking into single-cell RNA-seq data, the majority of DCX+ cells were classified as non-cancerous, with a small subset of cells that could be regarded as glioma stem cells. In conclusion, our findings support the notion that glioma cells express DCX; however, there is no clear evidence to prove that DCX participates in GBM cell migration.