RESUMEN
In terrestrial vertebrates, the olfactory system is divided into main (MOS) and accessory (AOS) components that process both volatile and nonvolatile cues to generate appropriate behavioral responses. While much is known regarding the molecular diversity of neurons that comprise the MOS, less is known about the AOS. Here, focusing on the vomeronasal organ (VNO), the accessory olfactory bulb (AOB), and the medial amygdala (MeA), we reveal that populations of neurons in the AOS can be molecularly subdivided based on their ongoing or prior expression of the transcription factors Foxp2 or Dbx1, which delineate separate populations of GABAergic output neurons in the MeA. We show that a majority of AOB neurons that project directly to the MeA are of the Foxp2 lineage. Using single-neuron patch-clamp electrophysiology, we further reveal that in addition to sex-specific differences across lineage, the frequency of excitatory input to MeA Dbx1- and Foxp2-lineage neurons differs between sexes. Together, this work uncovers a novel molecular diversity of AOS neurons, and lineage and sex differences in patterns of connectivity.
Asunto(s)
Complejo Nuclear Corticomedial , Órgano Vomeronasal , Animales , Femenino , Masculino , Bulbo Olfatorio/fisiología , Órgano Vomeronasal/fisiología , Caracteres Sexuales , Neuronas GABAérgicasRESUMEN
The hypothalamus integrates information required for the production of a variety of innate behaviors such as feeding, mating, aggression, and predator avoidance. Despite an extensive knowledge of hypothalamic function, how embryonic genetic programs specify circuits that regulate these behaviors remains unknown. Here, we find that in the hypothalamus the developmentally regulated homeodomain-containing transcription factor Dbx1 is required for the generation of specific subclasses of neurons within the lateral hypothalamic area/zona incerta (LH) and the arcuate (Arc) nucleus. Consistent with this specific developmental role, Dbx1 hypothalamic-specific conditional-knockout mice display attenuated responses to predator odor and feeding stressors but do not display deficits in other innate behaviors such as mating or conspecific aggression. Thus, activity of a single developmentally regulated gene, Dbx1, is a shared requirement for the specification of hypothalamic nuclei governing a subset of innate behaviors. VIDEO ABSTRACT.
Asunto(s)
Conducta Animal/fisiología , Proteínas de Homeodominio/genética , Hipotálamo/embriología , Hipotálamo/fisiología , Instinto , Animales , Tipificación del Cuerpo/genética , Conducta Alimentaria/fisiología , Femenino , Expresión Génica , Proteínas de Homeodominio/metabolismo , Hipotálamo/citología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Masculino , Ratones , Ratones Noqueados , Neuronas/metabolismo , Neuropéptidos/metabolismo , OrexinasRESUMEN
BACKGROUND: The basolateral complex, comprised of the lateral, basolateral, and basomedial nuclei, is the main structure of the amygdala and contains two neuronal cell types: excitatory neurons and inhibitory interneurons. Studies show that most of the excitatory neurons originate in the ventral pallium of the telencephalon. However, their subsequent development remains poorly understood. RESULTS: In this study, we examined the roles of the zinc finger gene Fezf2 in the development of the amygdala. Fezf2 is expressed in the lateral and basolateral nuclei during development. In Fezf2-deficient embryos, specific excitatory neuron markers in the lateral and basolateral nuclei were reduced, with concurrent induction of other markers in the endopiriform cortex. Furthermore, the morphology of the lateral and basolateral nuclei was abnormal. In the adult stages, excitatory neurons in the lateral and basolateral nuclei were greatly reduced because of apoptosis that occurred soon after birth. CONCLUSIONS: These results suggest that Fezf2 is required for the development of excitatory neurons and nuclear morphology in the lateral and basolateral nuclei, and that abnormal formation of these regions leads to cell death soon after birth in Fezf2-deficient mice.
Asunto(s)
Amígdala del Cerebelo/citología , Neuronas/citología , Neuronas/metabolismo , Factores de Transcripción/metabolismo , Animales , Telencéfalo/citología , Factores de Transcripción/genéticaRESUMEN
A subset of preBötzinger Complex (preBötC) neurokinin 1 receptor (NK1R) and somatostatin peptide (SST)-expressing neurons are necessary for breathing in adult rats, in vivo. Their developmental origins and relationship to other preBötC glutamatergic neurons are unknown. Here we show, in mice, that the "core" of preBötC SST(+)/NK1R(+)/SST 2a receptor(+) (SST2aR) neurons, are derived from Dbx1-expressing progenitors. We also show that Dbx1-derived neurons heterogeneously coexpress NK1R and SST2aR within and beyond the borders of preBötC. More striking, we find that nearly all non-catecholaminergic glutamatergic neurons of the ventrolateral medulla (VLM) are also Dbx1 derived. PreBötC SST(+) neurons are born between E9.5 and E11.5 in the same proportion as non-SST-expressing neurons. Additionally, preBötC Dbx1 neurons are respiratory modulated and show an early inspiratory phase of firing in rhythmically active slice preparations. Loss of Dbx1 eliminates all glutamatergic neurons from the respiratory VLM including preBötC NK1R(+)/SST(+) neurons. Dbx1 mutant mice do not express any spontaneous respiratory behaviors in vivo. Moreover, they do not generate rhythmic inspiratory activity in isolated en bloc preparations even after acidic or serotonergic stimulation. These data indicate that preBötC core neurons represent a subset of a larger, more heterogeneous population of VLM Dbx1-derived neurons. These data indicate that Dbx1-derived neurons are essential for the expression and, we hypothesize, are responsible for the generation of respiratory behavior both in vitro and in vivo.
Asunto(s)
Diferenciación Celular/genética , Proteínas de Homeodominio/genética , Neurogénesis/genética , Neuronas/citología , Neuronas/fisiología , Centro Respiratorio/crecimiento & desarrollo , Animales , Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas de Homeodominio/fisiología , Ratones , Ratones Transgénicos , Células-Madre Neurales/citología , Células-Madre Neurales/metabolismo , Neuronas/efectos de los fármacos , Técnicas de Cultivo de Órganos , Receptores de Neuroquinina-1/fisiología , Receptores de Somatostatina/genética , Receptores de Somatostatina/fisiología , Centro Respiratorio/citología , Centro Respiratorio/efectos de los fármacos , Fenómenos Fisiológicos Respiratorios/genética , Somatostatina/metabolismo , Somatostatina/fisiologíaRESUMEN
In the developing mammalian basal telencephalon, neural progenitors from the subpallium generate the majority of inhibitory medium spiny neurons (MSNs) in the striatum, while both pallial- and subpallial-derived progenitors contribute to excitatory and inhibitory neuronal diversity in the amygdala. Using a combination of approaches, including genetic fate mapping, cell birth dating, cell migration assays, and electrophysiology, we find that cells derived from the Emx1 lineage contribute to two distinct neuronal populations in the mature basal forebrain: inhibitory MSNs in the striatum and functionally distinct subclasses of excitatory neurons in the amygdala. Our cell birth-dating studies reveal that these two populations are born at different times during early neurogenesis, with the amygdala population born before the MSNs. In the striatum, Emx1-lineage neurons represent a unique subpopulation of MSNs: they are disproportionately localized to the dorsal striatum, are found in dopamine receiving, reelin-positive patches, and are born throughout striatal neurogenesis. In addition, our data suggest that a subpopulation of these Emx1-lineage cells originate in the pallium and subsequently migrate to the developing striatum and amygdala. Our intersectional fate-mapping analysis further reveals that Emx1-lineage cells that coexpress Dlx exclusively generate MSNs but do not contribute to the excitatory neurons in the amygdala. Thus, both the timing of neurogenesis and differential combinatorial gene expression appear to be key determinants of striatal versus amygdala fate decisions of Emx1-lineage cells.
Asunto(s)
Amígdala del Cerebelo/fisiología , Diferenciación Celular/fisiología , Linaje de la Célula/fisiología , Cuerpo Estriado/fisiología , Proteínas de Homeodominio/fisiología , Células Madre/fisiología , Factores de Transcripción/fisiología , Amígdala del Cerebelo/citología , Amígdala del Cerebelo/embriología , Animales , Diferenciación Celular/genética , Linaje de la Célula/genética , Cuerpo Estriado/citología , Cuerpo Estriado/embriología , Femenino , Proteínas de Homeodominio/biosíntesis , Proteínas de Homeodominio/genética , Ratones , Ratones Endogámicos C57BL , Neurogénesis/genética , Neurogénesis/fisiología , Neuronas/clasificación , Neuronas/citología , Neuronas/fisiología , Embarazo , Proteína Reelina , Células Madre/clasificación , Células Madre/citología , Factores de Transcripción/biosíntesis , Factores de Transcripción/genéticaRESUMEN
The development of the amygdala, a central structure of the limbic system, remains poorly understood. We found that two spatially distinct and early-specified telencephalic progenitor pools marked by the homeodomain transcription factor Dbx1 are major sources of neuronal cell diversity in the mature mouse amygdala. We found that Dbx1-positive cells of the ventral pallium generate the excitatory neurons of the basolateral complex and cortical amygdala nuclei. Moreover, Dbx1-derived cells comprise a previously unknown migratory stream that emanates from the preoptic area (POA), a ventral telencephalic domain adjacent to the diencephalic border. The Dbx1-positive, POA-derived population migrated specifically to the amygdala and, as defined by both immunochemical and electrophysiological criteria, generated a unique subclass of inhibitory neurons in the medial amygdala nucleus. Thus, this POA-derived population represents a previously unknown progenitor pool dedicated to the limbic system.
Asunto(s)
Amígdala del Cerebelo/citología , Amígdala del Cerebelo/embriología , Proteínas de Homeodominio/metabolismo , Neuronas/citología , Nicho de Células Madre/citología , Células Madre/citología , Amígdala del Cerebelo/fisiología , Animales , Movimiento Celular/fisiología , Femenino , Técnicas de Sustitución del Gen , Proteínas de Homeodominio/genética , Integrasas/genética , Operón Lac , Masculino , Potenciales de la Membrana/fisiología , Ratones , Ratones Mutantes , Ratones Transgénicos , Inhibición Neural/fisiología , Técnicas de Placa-Clamp , Embarazo , Área Preóptica/citología , Área Preóptica/embriología , Área Preóptica/fisiología , Nicho de Células Madre/fisiología , Células Madre/fisiologíaRESUMEN
In the embryonic telencephalon, the pallial-subpallial boundary (PSB) separates the dorsal Pax6+ pallium from the ventral Gsh2+ subpallium. Previous studies have revealed that this region is a source of cells that will populate both the olfactory bulb and basal telencephalic limbic system. However, the level of progenitor cell heterogeneity and developmental genetic regulation of this progenitor region remains to be fully elucidated. In this study we carried out a comprehensive analysis of gene expression patterns at the PSB, in addition to an examination of the combinatorial function of Pax6 and Gsh2 in the specification of the PSB. First, we reveal that the PSB is comprised of a complex mix of molecularly distinct progenitor pools. In addition, by analysis of single Sey, Gsh2, and Sey/Gsh2 double mutant mice, we demonstrate that both Pax6 and Gsh2 are directly required for major aspects of PSB progenitor specification. Our analysis also reveals that the establishment of the epidermal growth factor receptor positive lateral cortical stream migratory route to the basal telencephalon is Pax6 dependent. Thus, in addition to their well-characterized cross-repressive roles in dorsal/ventral patterning our analyses reveal important novel functions of Gsh2 and Pax6 in the regulation of PSB progenitor pool specification and patterning.
Asunto(s)
Tipificación del Cuerpo/fisiología , Movimiento Celular/fisiología , Proteínas del Ojo/fisiología , Globo Pálido/fisiología , Proteínas de Homeodominio/fisiología , Factores de Transcripción Paired Box/fisiología , Proteínas Represoras/fisiología , Telencéfalo/fisiología , Animales , Receptores ErbB/fisiología , Femenino , Globo Pálido/citología , Globo Pálido/embriología , Masculino , Ratones , Ratones Noqueados , Ratones Transgénicos , Neuronas/citología , Neuronas/metabolismo , Neuronas/fisiología , Factor de Transcripción PAX6 , Embarazo , Células Madre/citología , Células Madre/metabolismo , Células Madre/fisiología , Telencéfalo/citología , Telencéfalo/embriologíaRESUMEN
Fluorescent semiconductor nanocrystal quantum dots (QDs) are a class of multifunctional inorganic fluorophores that hold great promise for clinical applications and biomedical research. Because no methods currently exist for directed QD-labeling of mammalian cells in the nervous system in vivo, we developed novel in utero electroporation and ultrasound-guided in vivo delivery techniques to efficiently and directly label neural stem and progenitor cells (NSPCs) of the developing mammalian central nervous system with QDs. Our initial safety and proof of concept studies of one and two-cell QD-labeled mouse embryos reveal that QDs are compatible with early mammalian embryonic development. Our in vivo experiments further show that in utero labeled NSPCs continue to develop in an apparent normal manner. These studies reveal that QDs can be effectively used to label mammalian NSPCs in vivo and will be useful for studies of in vivo fate mapping, cellular migration, and NSPC differentiation during mammalian development.
Asunto(s)
Células Madre Embrionarias/citología , Puntos Cuánticos , Animales , Diferenciación Celular , Células Cultivadas , Electroporación , Desarrollo Embrionario , Femenino , Colorantes Fluorescentes , Ratones , Neuronas/citología , Embarazo , SeguridadRESUMEN
Fez and Fez-like (Fezl) are zinc-finger genes that encode transcriptional repressors expressed in overlapping domains of the forebrain. By generating Fez;Fezl-deficient mice we found that a redundant function of Fez and Fezl is required for the formation of diencephalon subdivisions. The caudal forebrain can be divided into three transverse subdivisions: prethalamus (also called ventral thalamus), thalamus (dorsal thalamus) and pretectum. Fez;Fezl-deficient mice showed a complete loss of prethalamus and a strong reduction of the thalamus at late gestation periods. Genetic marker analyses revealed that during early diencephalon patterning in Fez;Fezl-deficient mice, the rostral diencephalon (prospective prethalamus) did not form and the caudal diencephalon (prospective thalamus and pretectum) expanded rostrally. Fez;Fezl-deficient mice also displayed defects in the formation of the zona limitans intrathalamica (ZLI), which is located on the boundary between the prethalamus and thalamus. Fez and Fezl are expressed in the region rostral to the rostral limit of Irx1 expression, which marks the prospective position of the ZLI. Transgene-mediated misexpression of Fezl or Fez caudal to the ZLI repressed the caudal diencephalon fate and affected the formation of the Shh-expressing ZLI. These data indicate that Fez and Fezl repress the caudal diencephalon fate in the rostral diencephalon, and ZLI formation probably depends on Fez/Fezl-mediated formation of diencephalon subdivisions.
Asunto(s)
Tipificación del Cuerpo/genética , Proteínas de Unión al ADN/fisiología , Diencéfalo/embriología , Proteínas del Tejido Nervioso/fisiología , Animales , Proteínas de Unión al ADN/análisis , Proteínas de Unión al ADN/genética , Diencéfalo/anomalías , Diencéfalo/anatomía & histología , Elementos de Facilitación Genéticos , Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Ratones , Ratones Transgénicos , Proteínas del Tejido Nervioso/análisis , Proteínas del Tejido Nervioso/genética , Regiones Promotoras Genéticas , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Dedos de ZincRESUMEN
Fez is a zinc-finger gene encoding a transcriptional repressor that is expressed in the olfactory epithelium, hypothalamus, ventrolateral pallium and prethalamus at mid-gestation. To reveal its function, we generated Fez-deficient mice. The Fez-deficient mice showed several abnormalities in the olfactory system: (1) impaired axonal projection of the olfactory sensory neurons; (2) reduced size of the olfactory bulb; (3) abnormal layer formation in the olfactory bulb; and (4) aberrant rostral migration of the interneuron progenitors. Fez was not expressed in the projection neurons, interneurons or interneuron progenitors. Transgene-mediated expression of Fez in olfactory sensory neurons significantly rescued the abnormalities in olfactory axon projection and in the morphogenesis of the olfactory bulb in Fez-knockout mice. Thus, Fez is cell-autonomously required for the axon termination of olfactory sensory neurons, and Fez non-cell-autonomously controls layer formation and interneuron development in the olfactory bulb. These findings suggest that signals from olfactory sensory neurons contribute to the proper formation of the olfactory bulb.
Asunto(s)
Proteínas de Unión al ADN/genética , Proteínas del Tejido Nervioso/genética , Neuronas Aferentes/metabolismo , Neuronas Aferentes/fisiología , Bulbo Olfatorio/embriología , Dedos de Zinc/genética , Animales , Transporte Axonal/genética , Diferenciación Celular/genética , Movimiento Celular/genética , Cruzamientos Genéticos , Proteínas de Unión al ADN/biosíntesis , Proteínas de Unión al ADN/deficiencia , Proteínas de Unión al ADN/fisiología , Femenino , Interneuronas/citología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Datos de Secuencia Molecular , Proteínas del Tejido Nervioso/biosíntesis , Proteínas del Tejido Nervioso/deficiencia , Proteínas del Tejido Nervioso/fisiología , Neuronas Aferentes/citología , Bulbo Olfatorio/citología , Transducción de Señal/genética , Células Madre/metabolismoRESUMEN
sax1/nkx1.2 and sax2/nkx1.1 are members of the evolutionally conserved NK-1 homeobox gene family. sax1/nkx1.2 is reported to be expressed in the central nervous system during early and late neurogenesis in the chick and mouse, but the expression of sax2/nkx1.1 has not been reported. We isolated zebrafish cDNAs for sax1/nkx1.2 and sax2/nkx1.1 and examined their expression. In zebrafish, unlike chick and mouse, sax1/nkx1.2 was expressed in the prospective medial floor plate from the mid-gastrula period and was dependent on Nodal signaling. From the early segmentation period, sax1/nkx1.2 was also expressed in the posterior neuroectoderm. sax2/nkx1.1 was expressed in the prospective extraocular muscles, mesencephalic neurons residing along the tract of the posterior commissure, ventral neurons in the hindbrain, and interneurons in the spinal cord.
Asunto(s)
Sistema Nervioso Central/embriología , Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas de Homeodominio/biosíntesis , Factores de Transcripción/biosíntesis , Proteínas de Pez Cebra/biosíntesis , Pez Cebra/embriología , Animales , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas de Homeodominio/genética , Humanos , Datos de Secuencia Molecular , Proteína Nodal , Transducción de Señal/fisiología , Factores de Transcripción/genética , Factor de Crecimiento Transformador beta/metabolismo , Pez Cebra/genética , Proteínas de Pez Cebra/genéticaRESUMEN
In zebrafish, the program for dorsal specification begins soon after fertilization. Dorsal determinants are localized initially to the vegetal pole, then transported to the blastoderm, where they are thought to activate the canonical Wnt pathway, which induces the expression of dorsal-specific genes. We identified a novel maternal-effect recessive mutation, tokkaebi (tkk), that affects formation of the dorsal axis. Severely ventralized phenotypes, including a lack of dorso-anterior structures, were seen in 5-100% of the embryos obtained from tkk homozygous transmitting females. tkk embryos displayed defects in the nuclear accumulation of beta-catenin on the dorsal side, and reduced or absent expression of dorsal-specific genes. Mesoderm and endoderm formation outside the dorsal axis was not significantly affected. Injection of RNAs for activated beta-catenin, dominant-negative forms of Axin1 and GSK3beta, and wild-type Dvl3, into the tkk embryos suppressed the ventralized phenotypes and/or dorsalized the embryos, and restored or induced an ectopic and expanded expression of bozozok/dharma and goosecoid. However, dorsalization by wnt RNAs was affected in the tkk embryos. Inhibition of cytoplasmic calcium release elicited an ectopic and expanded expression of chordin in the wild-type, but did not restore chordin expression efficiently in the tkk embryos. These data indicate that the tkk gene product functions upstream of or parallel to the beta-catenin-degradation machinery to control the stability of beta-catenin. The tkk locus was mapped to chromosome 16. These data provide genetic evidence that the maternally derived canonical Wnt pathway upstream of beta-catenin is involved in dorsal axis formation in zebrafish.
Asunto(s)
Tipificación del Cuerpo/genética , Proteínas Proto-Oncogénicas/genética , Transducción de Señal/genética , Pez Cebra/embriología , Animales , Tipificación del Cuerpo/fisiología , Señalización del Calcio/fisiología , Núcleo Celular/metabolismo , Mapeo Cromosómico , Cruzamientos Genéticos , Proteínas del Citoesqueleto/metabolismo , Ligandos , Organizadores Embrionarios/fisiología , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal/fisiología , Transactivadores/metabolismo , Proteínas Wnt , Pez Cebra/genética , Pez Cebra/metabolismo , Proteínas de Pez Cebra , beta CateninaRESUMEN
The zebrafish mutant ogon (also called mercedes and short tail) displays ventralized phenotypes similar to the chordino (dino) mutant, in which the gene for the Bmp antagonist Chordin is mutated. We isolated the gene responsible for ogon by a positional cloning strategy and found that the ogon locus encodes a zebrafish homolog of Secreted Frizzled (Sizzled), which has sequence similarity to a Wnt receptor, Frizzled. Unlike other secreted Frizzled-related proteins (sFrps) and the Wnt inhibitor Dickkopf1, the misexpression of Ogon/Sizzled dorsalized, but did not anteriorize, the embryos, suggesting a role for Ogon/Sizzled in Bmp inhibition. Ogon/Sizzled did not inhibit a Wnt8-dependent transcription in the zebrafish embryo. ogon/sizzled was expressed on the ventral side from the late blastula through the gastrula stages. The ventral ogon/sizzled expression in the gastrula stage was reduced or absent in the swirl/bmp2b mutants but expanded in the chordino mutants. Misexpression of ogon/sizzled did not dorsalize the chordino mutants, suggesting that Ogon/Sizzled required Chordin protein for dorsalization and Bmp inhibition. These data indicate that Ogon/Sizzled functions as a negative regulator of Bmp signaling and reveal a novel role for a sFrp in dorsoventral patterning.
Asunto(s)
Proteínas Morfogenéticas Óseas/metabolismo , Glicoproteínas , Péptidos y Proteínas de Señalización Intercelular , Proteínas/metabolismo , Proteínas de Xenopus , Proteínas de Pez Cebra , Secuencia de Aminoácidos , Animales , Tipificación del Cuerpo/fisiología , Retroalimentación Fisiológica , Datos de Secuencia Molecular , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Wnt , Pez Cebra/embriología , Pez Cebra/metabolismoRESUMEN
A homeobox gene, pnx, is expressed in prospective posterior neurogenic regions and later in primary neurons. pnx expression was regulated by a signal from the non-axial mesendoderm and by Notch signaling. Pnx contains an Eh1 repressor domain, which interacted with Groucho and acted as a transcriptional repressor. Misexpression of pnx increased neural precursor cells and postmitotic neurons, which express neurogenin1 and elavl3/HuC, respectively. Expression of an antimorphic Pnx (VP16Pnx) or inhibition of Pnx by antisense morpholino oligonucleotide led to the reduction in the number of a subset of primary neurons. Misexpression of pnx promoted neurogenesis independent of Notch signaling. Epistatic analyses showed that Pnx also functions downstream of the Notch signal. These data indicate that pnx is a novel repressor-type homeobox gene that regulates posterior neurogenesis.