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1.
Nat Commun ; 10(1): 2129, 2019 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-31086189

RESUMO

De novo heterozygous missense variants in the γ-tubulin gene TUBG1 have been linked to human malformations of cortical development associated with intellectual disability and epilepsy. Here, we investigated through in-utero electroporation and in-vivo studies, how four of these variants affect cortical development. We show that TUBG1 mutants affect neuronal positioning, disrupting the locomotion of new-born neurons but without affecting progenitors' proliferation. We further demonstrate that pathogenic TUBG1 variants are linked to reduced microtubule dynamics but without major structural nor functional centrosome defects in subject-derived fibroblasts. Additionally, we developed a knock-in Tubg1Y92C/+ mouse model and assessed consequences of the mutation. Although centrosomal positioning in bipolar neurons is correct, they fail to initiate locomotion. Furthermore, Tubg1Y92C/+ animals show neuroanatomical and behavioral defects and increased epileptic cortical activity. We show that Tubg1Y92C/+ mice partially mimic the human phenotype and therefore represent a relevant model for further investigations of the physiopathology of cortical malformations.


Assuntos
Malformações do Desenvolvimento Cortical/genética , Microtúbulos/metabolismo , Neurogênese/genética , Neurônios/fisiologia , Tubulina (Proteína)/genética , Animais , Comportamento Animal , Movimento Celular/genética , Centrossomo/metabolismo , Córtex Cerebral/anormalidades , Córtex Cerebral/citologia , Córtex Cerebral/diagnóstico por imagem , Modelos Animais de Doenças , Embrião de Mamíferos , Epilepsia/genética , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Células HeLa , Humanos , Microscopia Intravital , Masculino , Camundongos , Camundongos Transgênicos , Microscopia Confocal , Microscopia Eletrônica , Microtúbulos/genética , Mutação de Sentido Incorreto
2.
Nature ; 567(7746): 113-117, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30787442

RESUMO

The expansion of brain size is accompanied by a relative enlargement of the subventricular zone during development. Epithelial-like neural stem cells divide in the ventricular zone at the ventricles of the embryonic brain, self-renew and generate basal progenitors1 that delaminate and settle in the subventricular zone in enlarged brain regions2. The length of time that cells stay in the subventricular zone is essential for controlling further amplification and fate determination. Here we show that the interphase centrosome protein AKNA has a key role in this process. AKNA localizes at the subdistal appendages of the mother centriole in specific subtypes of neural stem cells, and in almost all basal progenitors. This protein is necessary and sufficient to organize centrosomal microtubules, and promote their nucleation and growth. These features of AKNA are important for mediating the delamination process in the formation of the subventricular zone. Moreover, AKNA regulates the exit from the subventricular zone, which reveals the pivotal role of centrosomal microtubule organization in enabling cells to both enter and remain in the subventricular zone. The epithelial-to-mesenchymal transition is also regulated by AKNA in other epithelial cells, demonstrating its general importance for the control of cell delamination.


Assuntos
Centrossomo/metabolismo , Proteínas de Ligação a DNA/metabolismo , Ventrículos Laterais/citologia , Ventrículos Laterais/embriologia , Microtúbulos/metabolismo , Neurogênese , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Animais , Movimento Celular , Células Cultivadas , Células Epiteliais/metabolismo , Transição Epitelial-Mesenquimal , Humanos , Junções Intercelulares/metabolismo , Interfase , Ventrículos Laterais/anatomia & histologia , Glândulas Mamárias Animais/citologia , Camundongos , Tamanho do Órgão , Organoides/citologia
3.
Hum Mol Genet ; 27(2): 224-238, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29077851

RESUMO

Genetic findings reported by our group and others showed that de novo missense variants in the KIF2A gene underlie malformations of brain development called pachygyria and microcephaly. Though KIF2A is known as member of the Kinesin-13 family involved in the regulation of microtubule end dynamics through its ATP dependent MT-depolymerase activity, how KIF2A variants lead to brain malformations is still largely unknown. Using cellular and in utero electroporation approaches, we show here that KIF2A disease-causing variants disrupts projection neuron positioning and interneuron migration, as well as progenitors proliferation. Interestingly, further dissection of this latter process revealed that ciliogenesis regulation is also altered during progenitors cell cycle. Altogether, our data suggest that deregulation of the coupling between ciliogenesis and cell cycle might contribute to the pathogenesis of KIF2A-related brain malformations. They also raise the issue whether ciliogenesis defects are a hallmark of other brain malformations, such as those related to tubulins and MT-motor proteins variants.

4.
FEBS Lett ; 591(24): 3978-3992, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29194577

RESUMO

The cerebral cortex is a complex structure that contains different classes of neurons distributed within six layers and regionally organized into highly specialized areas. Cortical layering arises during embryonic development in an inside-out manner as forebrain progenitors proliferate and generate distinct waves of interneurons and projection neurons. Radial glial cells (RGCs) derive from neuroepithelial cells and are the founding cortical progenitors. At the onset of corticogenesis, RGCs expand their pool by proliferative divisions. As corticogenesis proceeds, they gradually undergo differentiative divisions to either generate neurons directly (direct neurogenesis) or indirectly via production of intermediate progenitors that further divide to generate pairs of neurons (indirect neurogenesis). The fate of RGCs is finely regulated during all the corticogenesis process and depends on time-scaled perception of external signals and expression of intrinsic factors. The present Review focuses on the role of physiological extracellular cues arising from the vicinity of neural progenitors on the regulation of dorsal neurogenesis and cerebral cortex patterning. It further discusses how pathogenic viral factors influence RGC behaviour and disrupt cerebral cortex development.


Assuntos
Linhagem da Célula/fisiologia , Córtex Cerebral/embriologia , Neurogênese/fisiologia , Animais , Diferenciação Celular , Córtex Cerebral/crescimento & desenvolvimento , Células Ependimogliais/fisiologia , Humanos , Células-Tronco Neurais/fisiologia , Neurônios/fisiologia
5.
Nat Genet ; 48(11): 1349-1358, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27694961

RESUMO

Neurodevelopmental disorders with periventricular nodular heterotopia (PNH) are etiologically heterogeneous, and their genetic causes remain in many cases unknown. Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay. Cellular and expression data showed sensitivity of PNH-associated mutants to proteasome degradation. Moreover, an in utero electroporation approach showed that PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation. Further investigations, including rapamycin-based experiments, found differential deregulation of pathways involved. Excess wild-type NEDD4L leads to disruption of Dab1 and mTORC1 pathways, while PNH-related mutations are associated with deregulation of mTORC1 and AKT activities. Altogether, these data provide insights into the critical role of NEDD4L in the regulation of mTOR pathways and their contributions in cortical development.


Assuntos
Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Mutação de Sentido Incorreto , Heterotopia Nodular Periventricular/genética , Ubiquitina-Proteína Ligases/genética , Animais , Células Cultivadas , Feminino , Humanos , Masculino , Camundongos , Ubiquitina-Proteína Ligases Nedd4 , Domínios Proteicos/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Ubiquitina/metabolismo
6.
Eur J Hum Genet ; 24(4): 611-4, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26395554

RESUMO

To unravel missing genetic causes underlying monogenic disorders with recurrence in sibling, we explored the hypothesis of parental germline mosaic mutations in familial forms of malformation of cortical development (MCD). Interestingly, four families with parental germline variants, out of 18, were identified by whole-exome sequencing (WES), including a variant in a new candidate gene, syntaxin 7. In view of this high frequency, revision of diagnostic strategies and reoccurrence risk should be considered not only for the recurrent forms, but also for the sporadic cases of MCD.


Assuntos
Mutação em Linhagem Germinativa , Malformações do Desenvolvimento Cortical/genética , Mosaicismo , Adulto , Exoma , Feminino , Loci Gênicos , Humanos , Masculino , Linhagem , Proteínas Qa-SNARE/genética
7.
Hum Mol Genet ; 23(6): 1516-26, 2014 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-24179174

RESUMO

Over the last years, the critical role of cytoskeletal proteins in cortical development including neuronal migration as well as in neuronal morphology has been well established. Inputs from genetic studies were provided through the identification of several mutated genes encoding either proteins associated with microtubules (DCX, LIS1, KIF2A, KIF5C, DYNC1H1) or tubulin subunits (TUBA1A, TUBB2B, TUBB5 and TUBG1), in malformations of cortical development (MCD). We also reported the identification of missense mutations in TUBB3, the postmitotic neuronal specific tubulin, in six different families presenting either polymicrogyria or gyral disorganization in combination with cerebellar and basal ganglial abnormalities. Here, we investigate further the association between TUBB3 mutations and MCDs by analyzing the consequences of Tubb3 knockdown on cortical development in mice. Using the in utero-electroporation approach, we demonstrate that Tubb3 knockdown leads to delayed bipolar morphology and radial migration with evidence, suggesting that the neuronal arrest is a transient phenomenon overcome after birth. Silenced blocked cells display a round-shape and decreased number of processes and a delay in the acquisition of the bipolar morphology. Also, more Tbr2 positive cells are observed, although less cells express the proliferation marker Ki67, suggesting that Tubb3 inactivation might have an indirect effect on intermediate progenitor proliferation. Furthermore, we show by rescue experiments the non-interchangeability of other beta-tubulins which are unable to rescue the phenotype. Our study highlights the critical and specific role of Tubb3 on the stereotyped morphological changes and polarization processes that are required for initiating radial migration to the cortical plate.


Assuntos
Movimento Celular , Córtex Cerebral/metabolismo , Malformações do Desenvolvimento Cortical/genética , Tubulina (Proteína)/metabolismo , Animais , Eletroporação , Feminino , Técnicas de Silenciamento de Genes , Humanos , Malformações do Desenvolvimento Cortical/patologia , Camundongos , Mutação de Sentido Incorreto , Gravidez , Isoformas de Proteínas , Tubulina (Proteína)/genética
8.
Nat Genet ; 45(6): 639-47, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23603762

RESUMO

The genetic causes of malformations of cortical development (MCD) remain largely unknown. Here we report the discovery of multiple pathogenic missense mutations in TUBG1, DYNC1H1 and KIF2A, as well as a single germline mosaic mutation in KIF5C, in subjects with MCD. We found a frequent recurrence of mutations in DYNC1H1, implying that this gene is a major locus for unexplained MCD. We further show that the mutations in KIF5C, KIF2A and DYNC1H1 affect ATP hydrolysis, productive protein folding and microtubule binding, respectively. In addition, we show that suppression of mouse Tubg1 expression in vivo interferes with proper neuronal migration, whereas expression of altered γ-tubulin proteins in Saccharomyces cerevisiae disrupts normal microtubule behavior. Our data reinforce the importance of centrosomal and microtubule-related proteins in cortical development and strongly suggest that microtubule-dependent mitotic and postmitotic processes are major contributors to the pathogenesis of MCD.


Assuntos
Dineínas do Citoplasma/genética , Cinesina/genética , Microcefalia/genética , Mutação de Sentido Incorreto , Tubulina (Proteína)/genética , Animais , Células COS , Movimento Celular , Cercopithecus aethiops , Exoma , Estudos de Associação Genética , Mutação em Linhagem Germinativa , Humanos , Lisencefalia/genética , Lisencefalia/patologia , Imagem por Ressonância Magnética , Malformações do Desenvolvimento Cortical/genética , Malformações do Desenvolvimento Cortical/patologia , Camundongos , Microcefalia/patologia , Modelos Moleculares , Neuroimagem , Linhagem , Análise de Sequência de DNA
9.
Haematologica ; 97(2): 168-78, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22298821

RESUMO

BACKGROUND: Expansion of hematopoietic stem cells represents an important objective for improving cell and gene therapy protocols. Retroviral transduction of the HoxB4 homeogene in mouse and human hematopoietic stem cells and hematopoietic progenitors is known to promote the cells' expansion. A safer approach consists in transferring homeobox proteins into hematopoietic stem cells taking advantage of the natural ability of homeoproteins to cross cell membranes. Thus, HOXB4 protein transfer is operative for expanding human hematopoietic cells, but such expansion needs to be improved. DESIGN AND METHODS: To that aim, we evaluated the effects of HOXC4, a protein encoded by a HOXB4 paralog gene, by co-culturing HOXC4-producing stromal cells with human CD34(+) hematopoietic cells. Numbers of progenitors and stem cells were assessed by in vitro cloning assays and injection into immuno-deficient mice, respectively. We also looked for activation or inhibition of target downstream gene expression. RESULTS: We show that the HOXC4 homeoprotein expands human hematopoietic immature cells by 3 to 6 times ex vivo and significantly improves the level of in vivo engraftment. Comparative transcriptome analysis of CD34(+) cells subjected or not to HOXB4 or HOXC4 demonstrated that both homeoproteins regulate the same set of genes, some of which encode key hematopoietic factors and signaling molecules. Certain molecules identified herein are factors reported to be involved in stem cell fate or expansion in other models, such as MEF2C, EZH2, DBF4, DHX9, YPEL5 and Pumilio. CONCLUSIONS: The present study may help to identify new HOX downstream key factors potentially involved in hematopoietic stem cell expansion or in leukemogenesis.


Assuntos
Células-Tronco Hematopoéticas/fisiologia , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Animais , Proliferação de Células , Células Cultivadas , Técnicas de Cocultura , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID
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