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KIF2A is an atypical kinesin that has the capacity to depolymerize microtubules. Patients carrying mutations in KIF2A suffer from progressive microcephaly and mental disabilities. While the role of this protein is well documented in neuronal migration, the relationship between its dysfunction and the pathobiology of brain disorders is unclear. Here, we report that KIF2A is dispensable for embryogenic neurogenesis but critical in postnatal stages for maturation, connectivity, and maintenance of neurons. We used a conditional approach to inactivate KIF2A in cortical progenitors, nascent postmitotic neurons, and mature neurons in mice. We show that the lack of KIF2A alters microtubule dynamics and disrupts several microtubule-dependent processes, including neuronal polarity, neuritogenesis, synaptogenesis, and axonal transport. KIF2A-deficient neurons exhibit aberrant electrophysiological characteristics, neuronal connectivity, and function, leading to their loss. The role of KIF2A is not limited to development, as fully mature neurons require KIF2A for survival. Our results emphasize an additional function of KIF2A and help explain how its mutations lead to brain disorders.
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Encefalopatías , Proteínas Represoras , Animales , Ratones , Proteínas Represoras/metabolismo , Cinesinas/genética , Microtúbulos/metabolismo , Neuronas/metabolismo , Encefalopatías/metabolismoRESUMEN
Having experienced stress during sensitive periods of brain development strongly influences how individuals cope with later stress. Some are prone to develop anxiety or depression, while others appear resilient. The as-yet-unknown mechanisms underlying these differences may lie in how genes and environmental stress interact to shape the circuits that control emotions. Here, we investigated the role of the habenulo-interpeduncular system (HIPS), a critical node in reward circuits, in early stress-induced anxiety in mice. We found that habenular and IPN components characterized by the expression of Otx2 are synaptically connected and particularly sensitive to chronic stress (CS) during the peripubertal period. Stress-induced peripubertal activation of this HIPS subcircuit elicits both HIPS hypersensitivity to later stress and susceptibility to develop anxiety. We also show that HIPS silencing through conditional Otx2 knockout counteracts these effects of stress. Together, these results demonstrate that a genetic factor, Otx2, and stress interact during the peripubertal period to shape the stress sensitivity of the HIPS, which is shown to be a key modulator of susceptibility or resilience to develop anxiety.
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Habénula , Resiliencia Psicológica , Ratones , Animales , Trastornos de Ansiedad/metabolismo , Emociones , Habénula/metabolismo , AnsiedadRESUMEN
The habenulo-interpeduncular system (HIPS) is now recognized as a critical circuit modulating aversion, reward, and social behavior. There is evidence that dysfunction of this circuit leads to psychiatric disorders. Because psychiatric diseases may originate in developmental abnormalities, it is crucial to investigate the developmental mechanisms controlling the formation of the HIPS. Thus far, this issue has been the focus of limited studies. Here, we explored the developmental processes underlying the formation of the medial habenula (MHb) and its unique output, the interpeduncular nucleus (IPN), in mice independently of their gender. We report that the Otx2 homeobox gene is essential for the proper development of both structures. We show that MHb and IPN neurons require Otx2 at different developmental stages and, in both cases, Otx2 deletion leads to disruption of HIPS subcircuits. Finally, we show that Otx2+ neurons tend to be preferentially interconnected. This study reveals that synaptically connected components of the HIPS, despite radically different developmental strategies, share high sensitivity to Otx2 expression.SIGNIFICANCE STATEMENT Brain reward circuits are highly complex and still poorly understood. In particular, it is important to understand how these circuits form as many psychiatric diseases may arise from their abnormal development. This work shows that Otx2, a critical evolutionary conserved gene implicated in brain development and a predisposing factor for psychiatric diseases, is required for the formation of the habenulo-interpeduncular system (HIPS), an important component of the reward circuit. Otx2 deletion affects multiple processes such as proliferation and migration of HIPS neurons. Furthermore, neurons expressing Otx2 are preferentially interconnected. Therefore, Otx2 expression may represent a code that specifies the connectivity of functional subunits of the HIPS. Importantly, the Otx2 conditional knock-out animals used in this study might represent a new genetic model of psychiatric diseases.
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Habénula/crecimiento & desarrollo , Núcleo Interpeduncular/crecimiento & desarrollo , Vías Nerviosas/crecimiento & desarrollo , Factores de Transcripción Otx/fisiología , Animales , Movimiento Celular/fisiología , Femenino , Regulación del Desarrollo de la Expresión Génica/genética , Regulación del Desarrollo de la Expresión Génica/fisiología , Habénula/fisiología , Núcleo Interpeduncular/fisiología , Masculino , Ratones , Ratones de la Cepa 129 , Ratones Noqueados , Vías Nerviosas/fisiología , Neuronas/fisiología , Sinapsis/fisiologíaRESUMEN
GABAergic interneurons are highly heterogeneous and originate in the subpallium mainly from the medial (MGE) and caudal (CGE) ganglionic eminences according to a precise temporal sequence. MGE-derived cells disperse dorsally and migrate towards all regions of the cortex, but little is known about how CGE-derived cells reach their targets during development. Here, we unravel the existence of two novel CGE caudo-rostral migratory streams, one located laterally (LMS) and the other one more medially (MMS), that, together with the well-known caudal migratory stream (CMS), contribute to populate the neocortex, hippocampus and amygdala. These paths appear in a precise temporal sequence and express a distinct combination of transcription factors, such as SP8, PROX1, COUP-TFI and COUP-TFII. By inactivating COUP-TFI in developing interneurons, the lateral and medial streams are perturbed and expression of SP8 and COUP-TFII affected. As a consequence, adult mutant neocortices have laminar-specific alterations of distinct cortical interneuron subtypes. Overall, we propose that the existence of spatially and temporally regulated migratory paths in the subpallium contributes to the laminar distribution and specification of distinct interneuron subpopulations in the adult brain.
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Encéfalo/citología , Encéfalo/embriología , Movimiento Celular , Interneuronas/citología , Eminencia Media/citología , Envejecimiento/metabolismo , Animales , Recuento de Células , Embrión de Mamíferos/citología , Embrión de Mamíferos/metabolismo , Proteínas Fluorescentes Verdes/metabolismo , Interneuronas/metabolismo , Ratones Transgénicos , Modelos Biológicos , Mutación/genética , Factores de Tiempo , Factores de Transcripción/metabolismoRESUMEN
A unique population of cells, called "lot cells," circumscribes the path of the lateral olfactory tract (LOT) in the rodent brain and acts to restrict its position at the lateral margin of the telencephalon. Lot cells were believed to originate in the dorsal pallium (DP). We show that Lhx2 null mice that lack a DP show a significant increase in the number of mGluR1/lot cells in the piriform cortex, indicating a non-DP origin of these cells. Since lot cells present common developmental features with Cajal-Retzius (CR) cells, we analyzed Wnt3a- and Dbx1-reporter mouse lines and found that mGluR1/lot cells are not generated in the cortical hem, ventral pallium, or septum, the best characterized sources of CR cells. Finally, we identified a novel origin for the lot cells by combining in utero electroporation assays and histochemical characterization. We show that mGluR1/lot cells are specifically generated in the lateral thalamic eminence and that they express mitral cell markers, although a minority of them express ΔNp73 instead. We conclude that most mGluR1/lot cells are prospective mitral cells migrating to the accessory olfactory bulb (OB), whereas mGluR1+, ΔNp73+ cells are CR cells that migrate through the LOT to the piriform cortex and the OB.
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Regulación del Desarrollo de la Expresión Génica/fisiología , Receptores de Glutamato Metabotrópico/metabolismo , Células Madre/fisiología , Tálamo/citología , Tálamo/metabolismo , Animales , Movimiento Celular , Células Cultivadas , Embrión de Mamíferos , Femenino , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Proteínas con Homeodominio LIM/genética , Proteínas con Homeodominio LIM/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos ICR , Ratones Transgénicos , Proteínas del Tejido Nervioso/metabolismo , Neurogénesis/fisiología , Embarazo , Receptores de Glutamato Metabotrópico/genética , Proteínas de Dominio T Box/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteína Tumoral p73/genética , Proteína Tumoral p73/metabolismoRESUMEN
Human mutations in ZIC2 have been identified in patients with holoprosencephaly and schizophrenia. Similarly, Zic2 mutant mice exhibit holoprosencephaly in homozygosis and behavioral and morphological schizophrenic phenotypes associated with forebrain defects in heterozygosis. Despite the devastating effects of mutations in Zic2, the cellular and molecular mechanisms that provoke Zic2-deficiency phenotypes are yet unclear. Here, we report a novel role for this transcription factor in the migration of three different types of forebrain neurons: the Cajal-Retzius cells that populate the surface of the telencephalic vesicles, an amygdaloid group of cells originated in the caudal pole of the telencephalic pallium, and a cell population that travels from the prethalamic neuroepithelium to the ventral lateral geniculate nucleus. Our results also suggest that the receptor EphB1, previously identified as a Zic2 target, may mediate, at least partially, Zic2-dependent migratory events. According to these results, we propose that deficiencies in cell motility and guidance contribute to most of the forebrain pathologies associated with Zic2 mutations. SIGNIFICANCE STATEMENT: Although the phenotype of Zic2 mutant individuals was reported more than 10 years ago, until now, the main function of this transcription factor during early development has not been precisely defined. Here, we reveal a previously unknown role for Zic2 in the migration of forebrain neurons such as Cajal-Retzius cells, interneurons moving to the ventral lateral geniculate nucleus, and neocortical cells going to the amygdala. We believe that the role of this transcription factor in certain populations of migratory cells contributes to defects in cortical layering and hypocellularity in the ventral LGN and amygdala and will contribute to our understanding of the devastating phenotypes associated with Zic2 mutations in both humans and mice.
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Movimiento Celular/fisiología , Neuronas/citología , Prosencéfalo/citología , Factores de Transcripción/metabolismo , Animales , Ratones , Ratones Transgénicos , Neuronas/metabolismo , Prosencéfalo/metabolismo , Receptor EphB1/genética , Receptor EphB1/metabolismo , Factores de Transcripción/genéticaRESUMEN
INTRODUCTION: The AUTS2 gene is associated with various neurodevelopmental and psychiatric disorders and has been suggested to play a role in acquiring human-specific traits. Functional analyses of Auts2 knockout mice have focused on postmitotic neurons, and the reported phenotypes do not faithfully recapitulate the whole spectrum of AUTS2-related human diseases. OBJECTIVE: The objective of the study is to assess the role of AUTS2 in the biology of neural progenitor cells, cortical neurogenesis and expansion; and understand how its deregulation leads to neurological disorders. METHODS: We screened the literature and conducted a time point analysis of AUTS2 expression during cortical development. We used in utero electroporation to acutely modulate the expression level of AUTS2 in the developing cerebral cortex in vivo, and thoroughly characterized cortical neurogenesis and morphogenesis using immunofluorescence, cell tracing and sorting, transcriptomic profiling, and gene ontology enrichment analyses. RESULTS: In addition to its expression in postmitotic neurons, we showed that AUTS2 is also expressed in neural progenitor cells at the peak of neurogenesis. Upregulation of AUTS2 dramatically altered the differentiation program and fate determination of cortical progenitors. Notably, it increased the number of basal progenitors and neurons and changed the expression of hundreds of genes, among which 444 have not been implicated in mouse brain development or function. CONCLUSION: The study provides evidence that AUTS2 is expressed in germinal zones and plays a key role in fate decision of neural progenitor cells with impact on corticogenesis. It also presents comprehensive lists of AUTS2 target genes thus advancing the molecular mechanisms underlying AUTS2-associated diseases and the evolutionary expansion of the cerebral cortex.
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Background: Glioblastoma is one of the most aggressive primary brain tumors, with a poor outcome despite multimodal treatment. Methylation of the MGMT promoter, which predicts the response to temozolomide, is a well-established prognostic marker for glioblastoma. However, a difference in survival can still be detected within the MGMT methylated group, with some patients exhibiting a shorter survival than others, emphasizing the need for additional predictive factors. Methods: We analyzed DIAPH3 expression in glioblastoma samples from the cancer genome atlas (TCGA). We also retrospectively analyzed one hundred seventeen histological glioblastomas from patients operated on at Saint-Luc University Hospital between May 2013 and August 2019. We analyzed the DIAPH3 expression, explored the relationship between mRNA levels and Patient's survival after the surgical resection. Finally, we assessed the methylation pattern of the DIAPH3 promoter using a targeted deep bisulfite sequencing approach. Results: We found that 36% and 1% of the TCGA glioblastoma samples exhibit copy number alterations and mutations in DIAPH3, respectively. We scrutinized the expression of DIAPH3 at single cell level and detected an overlap with MKI67 expression in glioblastoma proliferating cells, including neural progenitor-like, oligodendrocyte progenitor-like and astrocyte-like states. We quantitatively analyzed DIAPH3 expression in our cohort and uncovered a positive correlation between DIAPH3 mRNA level and patient's survival. The effect of DIAPH3 was prominent in MGMT-methylated glioblastoma. Finally, we report that the expression of DIAPH3 is at least partially regulated by the methylation of three CpG sites in the promoter region. Conclusion: We propose that combining the DIAPH3 expression with MGMT methylation could offer a better prediction of survival and more adapted postsurgical treatment for patients with MGMT-methylated glioblastoma.
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Malformation of cortical development (MCD) is a family of neurodevelopmental disorders, which usually manifest with intellectual disability and early-life epileptic seizures. Mutations in genes encoding microtubules (MT) and MT-associated proteins are one of the most frequent causes of MCD in humans. KIF2A is an atypical kinesin that depolymerizes MT in ATP-dependent manner and regulates MT dynamics. In humans, single de novo mutations in KIF2A are associated with MCD with epileptic seizures, posterior pachygyria, microcephaly, and partial agenesis of corpus callosum. In this study, we conditionally ablated KIF2A in forebrain inhibitory neurons and assessed its role in development and function of inhibitory cortical circuits. We report that adult mice with specific deletion of KIF2A in GABAergic interneurons display abnormal behavior and increased susceptibility to epilepsy. KIF2A is essential for tangential migration of cortical interneurons, their positioning in the cerebral cortex, and for formation of inhibitory synapses in vivo. Our results shed light on how KIF2A deregulation triggers functional alterations in neuronal circuitries and contributes to epilepsy.
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The tangential migration of immature neurons in the postnatal brain involves consecutive migration cycles and depends on constant remodeling of the cell cytoskeleton, particularly in the leading process (LP). Despite the identification of several proteins with permissive and empowering functions, the mechanisms that specify the direction of migration remain largely unknown. Here, we report that planar cell polarity protein Celsr3 orients neuroblasts migration from the subventricular zone (SVZ) to olfactory bulb (OB). In Celsr3-forebrain conditional knockout mice, neuroblasts loose directionality and few can reach the OB. Celsr3-deficient neuroblasts exhibit aberrant branching of LP, de novo LP formation, and decreased growth rate of microtubules (MT). Mechanistically, we show that Celsr3 interacts physically with Kif2a, a MT depolymerizing protein and that conditional inactivation of Kif2a in the forebrain recapitulates the Celsr3 knockout phenotype. Our findings provide evidence that Celsr3 and Kif2a cooperatively specify the directionality of neuroblasts tangential migration in the postnatal brain.
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Cadherinas , Cinesinas , Células-Madre Neurales , Neurogénesis , Receptores de Superficie Celular , Proteínas Represoras , Animales , Cadherinas/fisiología , Movimiento Celular/fisiología , Cinesinas/fisiología , Ventrículos Laterales/metabolismo , Ratones , Células-Madre Neurales/fisiología , Neurogénesis/fisiología , Bulbo Olfatorio/fisiología , Receptores de Superficie Celular/fisiología , Proteínas Represoras/fisiologíaRESUMEN
Diaphanous (DIAPH) three (DIAPH3) is a member of the formin proteins that have the capacity to nucleate and elongate actin filaments and, therefore, to remodel the cytoskeleton. DIAPH3 is essential for cytokinesis as its dysfunction impairs the contractile ring and produces multinucleated cells. Here, we report that DIAPH3 localizes at the centrosome during mitosis and regulates the assembly and bipolarity of the mitotic spindle. DIAPH3-deficient cells display disorganized cytoskeleton and multipolar spindles. DIAPH3 deficiency disrupts the expression and/or stability of several proteins including the kinetochore-associated protein SPAG5. DIAPH3 and SPAG5 have similar expression patterns in the developing brain and overlapping subcellular localization during mitosis. Knockdown of SPAG5 phenocopies DIAPH3 deficiency, whereas its overexpression rescues the DIAHP3 knockdown phenotype. Conditional inactivation of Diaph3 in mouse cerebral cortex profoundly disrupts neurogenesis, depleting cortical progenitors and neurons, leading to cortical malformation and autistic-like behavior. Our data uncover the uncharacterized functions of DIAPH3 and provide evidence that this protein belongs to a molecular toolbox that links microtubule dynamics during mitosis to aneuploidy, cell death, fate determination defects, and cortical malformation.
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Conducta Animal , Corteza Cerebral/metabolismo , Forminas/deficiencia , Microtúbulos/metabolismo , Mitosis , Neurogénesis , Neuronas/metabolismo , Huso Acromático/metabolismo , Animales , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Conducta Alimentaria , Forminas/genética , Regulación del Desarrollo de la Expresión Génica , Genotipo , Humanos , Locomoción , Aprendizaje por Laberinto , Ratones , Ratones Noqueados , Microtúbulos/genética , Microtúbulos/patología , Células 3T3 NIH , Neuronas/patología , Fenotipo , Conducta Social , Huso Acromático/genética , Huso Acromático/patologíaRESUMEN
Cell polarity refers to the asymmetric distribution of signaling molecules, cellular organelles, and cytoskeleton in a cell. Neural progenitors and neurons are highly polarized cells in which the cell membrane and cytoplasmic components are compartmentalized into distinct functional domains in response to internal and external cues that coordinate polarity and behavior during development and disease. In neural progenitor cells, polarity has a prominent impact on cell shape and coordinate several processes such as adhesion, division, and fate determination. Polarity also accompanies a neuron from the beginning until the end of its life. It is essential for development and later functionality of neuronal circuitries. During development, polarity governs transitions between multipolar and bipolar during migration of postmitotic neurons, and directs the specification and directional growth of axons. Once reaching final positions in cortical layers, neurons form dendrites which become compartmentalized to ensure proper establishment of neuronal connections and signaling. Changes in neuronal polarity induce signaling cascades that regulate cytoskeletal changes, as well as mRNA, protein, and vesicle trafficking, required for synapses to form and function. Hence, defects in establishing and maintaining cell polarity are associated with several neural disorders such as microcephaly, lissencephaly, schizophrenia, autism, and epilepsy. In this review we summarize the role of polarity genes in cortical development and emphasize the relationship between polarity dysfunctions and cortical malformations.
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In rodents, the medial nucleus of the amygdala receives direct inputs from the accessory olfactory bulbs and is mainly implicated in pheromone-mediated reproductive and defensive behaviors. The principal neurons of the medial amygdala are GABAergic neurons generated principally in the caudo-ventral medial ganglionic eminence and preoptic area. Beside GABAergic neurons, the medial amygdala also contains glutamatergic Otp-expressing neurons cells generated in the lateral hypothalamic neuroepithelium and a non-well characterized Pax6-positive population. In the present work, we describe a novel glutamatergic Ebf3-expressing neuronal subpopulation distributed within the periphery of the postero-ventral medial amygdala. These neurons are generated in a pallial domain characterized by high expression of Gdf10. This territory is topologically the most caudal tier of the ventral pallium and accordingly, we named it Caudo-Ventral Pallium (CVP). In the absence of Pax6, the CVP is disrupted and Ebf3-expressing neurons fail to be generated. Overall, this work proposes a novel model of the neuronal composition of the medial amygdala and unravels for the first time a new novel pallial subpopulation originating from the CVP and expressing the transcription factor Ebf3.
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Prosencéfalo Basal/metabolismo , Complejo Nuclear Corticomedial/metabolismo , Factor 10 de Diferenciación de Crecimiento/metabolismo , Células-Madre Neurales/metabolismo , Neuronas/metabolismo , Factores de Transcripción/metabolismo , Animales , Prosencéfalo Basal/embriología , Linaje de la Célula , Complejo Nuclear Corticomedial/embriología , Regulación del Desarrollo de la Expresión Génica , Edad Gestacional , Ácido Glutámico/metabolismo , Factor 10 de Diferenciación de Crecimiento/genética , Ratones Endogámicos C57BL , Ratones Endogámicos ICR , Ratones Noqueados , Factor de Transcripción PAX6/genética , Factor de Transcripción PAX6/metabolismo , Técnicas de Cultivo de Tejidos , Factores de Transcripción/genéticaRESUMEN
The generation and differentiation of an appropriate number of neurons, as well as its distribution in different parts of the brain, is crucial for the proper establishment, maintenance and plasticity of neural circuitries. Newborn neurons travel along the brain in a process known as neuronal migration, to finalize their correct position in the nervous system. Defects in neuronal migration produce abnormalities in the brain that can generate neurodevelopmental pathologies, such as autism, schizophrenia and intellectual disability. In this review, we present an overview of the developmental origin of the different telencephalic subdivisions and a description of migratory pathways taken by distinct neural populations traveling long distances before reaching their target position in the brain. In addition, we discuss some of the molecules implicated in the guidance of these migratory paths and transcription factors that contribute to the correct migration and integration of these neurons.