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Tubb5 perturbation causes microcephaly in the mouse. (A-D) Nisslstained coronal sections of the adult brain of mice of the indicated genotypes. (E-H) Axial magnetic resonance images (MRIs) of adult mice brains of the indicated genotypes. (I,J) Quantification of total brain (I) and cortical (J) volume, including a heterozygous floxed line without Cre as an additional control. (K,L) Quantification of cortical thickness during development and in adulthood for the E401K knock-in (K) and the knockout (L) lines. (I-L) Mean±s.e.m. ** /## P<0.01, ***P<0.001, ****P<0.0001 (* and # in K indicate significance relative to Tubb5 E401K/+ and Tubb5 E401K/+ ; Nestin-Cre, respectively) by (I,J) a one-way ANOVA with a Bonferroni post test for multiple comparisons for the knock-in and a two-tailed Student's t-test for the knockout and (K,L) a two-way ANOVA with a Bonferroni post test for multiple comparisons. n=3 for all conditions. Scale bars: 1 mm in D; 2 mm in H.
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Microtubules play a critical role in the generation, migration, and differentiation of nascent neurons in the developing vertebrate brain. Mutations in the constituents of microtubules, the tubulins, are known to cause an array of neurological disorders, including lissencephaly, polymicrogyria, and microcephaly. In this study we explore the genetic...
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... order to explore the genetic and cellular pathology underlying TUBB5 perturbations we engineered two conditional Tubb5 transgenic mouse lines: a conditional knock-in of the E401K patient mutation and a conditional knockout (Fig. S1A). Both the conditional knock-in and the knockout lines rely on loxP sites flanking the terminal exon (exon 4). In the case of the E401K knock- in, a modified version of exon 4 containing the E401K amino acid substitution was inserted downstream of this exon, permitting its conditional activation. mRNA analysis showed that, in the ...
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... allowing for the specific investigation of the E401K knock-in and the knockout in the developing brain ( Tronche et al., 1999). In the presence of this Cre recombinase, cDNA sequencing confirmed that the E401K mutation is expressed, and qPCR analysis at embryonic day (E) 14.5 showed that Tubb5 is expressed at similar levels as in controls (Fig. ...
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... analysed adult mice, employing Nissl stains and volumetric magnetic resonance imaging (MRI). Unexpectedly, we found that heterozygous E401K animals expressing the Cre recombinase (Tubb5 E401K/+ ;Nestin-Cre) showed no significant reduction in brain size in comparison to littermate controls (Tubb5 E401K/+ ) (Fig. 1A,B,E,F). This contrasted with homozygous E401K animals and heterozygous Tubb5 null alleles, both of which presented with large reductions in total brain (Tubb5 E401K/E401K ;Nestin-Cre, P<0.0001; Tubb5 fl/+ ;Nestin-Cre, P<0.0001; n=3) and cortical (Tubb5 E401K/E401K ;Nestin-Cre, P<0.0001; Tubb5 fl/+ ;Nestin-Cre, P=0.0025; n=3) volume (Fig. ...
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... ) (Fig. 1A,B,E,F). This contrasted with homozygous E401K animals and heterozygous Tubb5 null alleles, both of which presented with large reductions in total brain (Tubb5 E401K/E401K ;Nestin-Cre, P<0.0001; Tubb5 fl/+ ;Nestin-Cre, P<0.0001; n=3) and cortical (Tubb5 E401K/E401K ;Nestin-Cre, P<0.0001; Tubb5 fl/+ ;Nestin-Cre, P=0.0025; n=3) volume (Fig. 1C,D,G-J). This reduction was also observed in other brain regions, including the corpus callosum, cerebellum, hippocampus and putamen (Fig. S2D,E). Cortical thickness was similar in affected animals and wild-type littermate controls at E12.5, E14.5 and E16.5 (Fig. 1K,L). However, at postnatal day (P) 0 the cortex was notably thinner in ...
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... E401K/E401K ;Nestin-Cre, P<0.0001; Tubb5 fl/+ ;Nestin-Cre, P=0.0025; n=3) volume (Fig. 1C,D,G-J). This reduction was also observed in other brain regions, including the corpus callosum, cerebellum, hippocampus and putamen (Fig. S2D,E). Cortical thickness was similar in affected animals and wild-type littermate controls at E12.5, E14.5 and E16.5 (Fig. 1K,L). However, at postnatal day (P) 0 the cortex was notably thinner in affected lines, and severely reduced in adulthood (Tubb5 E401K/E401K ;Nestin-Cre, P<0.01; Tubb5 fl/+ ;Nestin-Cre, P<0.001; n=3). This suggests that the underlying defect has its origin in development and is exacerbated postnatally (Fig. 1K,L). Attempts to generate adult ...
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... controls at E12.5, E14.5 and E16.5 (Fig. 1K,L). However, at postnatal day (P) 0 the cortex was notably thinner in affected lines, and severely reduced in adulthood (Tubb5 E401K/E401K ;Nestin-Cre, P<0.01; Tubb5 fl/+ ;Nestin-Cre, P<0.001; n=3). This suggests that the underlying defect has its origin in development and is exacerbated postnatally (Fig. 1K,L). Attempts to generate adult homozygous null animals driven by Nestin-Cre were unsuccessful owing to prenatal and early postnatal lethality (no animals could be recovered past weaning ...
Citations
... A patologia cerebral dos recem-nascidos acometidos pela infecção do ZIKAV assemelha-se muito à neuropatologia associada ao citomegalovírus, podem a diferença mais notável é a distribuição de calcificações intracranianas, em que nas infecções pelo ZIKAV são tipicamente subcorticais e periventriculares em CMV(24). Tais calcificações são provavelmente distróficas e relacionadas à morte celular por ativação da proteína P53 causando necrose, apoptose ou ambos(25,26,27). ...
O vírus Zika (ZIKAV) trata-se de um flavivírus, causador de uma arbovirose de importância epidemiológica principalmente em países tropicais o que foi isolado pela primeira vez em 1947 a partir de um macaco na floresta Zika em Uganda e, posteriormente em humanos na Nigéria. No Brasil, em maio de 2015, foi identificada a infecção pelo ZIKAV, este expandiu-se pelas América e o que coincidiu com o aumento de complicações neurológicas como a microcefalia congênita e inúmeros casos de síndrome de Guillain-Barré, uma doença autoimune que pode causar paralisia flácida aguda, arreflexia e ascendente. Recentemente alguns relatos do Ministério da Saúde do Brasil mostraram que os casos de microcefalia congênita aumentaram entre os recém-nascidos da região nordeste do país, indicando uma provável associação com a infecção pelo ZIKAV na gestação. estudo apresentou como finalidade inquirir na literatura a patogênese da microcefalia causada pelo ZIKAV e apresentação do fenótipo dos recém-nascidos acometidos pela infecção pré-natal, prognóstico e resultados da neuroestimulação precoce desses recém-nascidos acometidos. foi elaborado a partir de uma revisão da literatura nas bases de dados eletrônicas BVS (Biblioteca Virtual em Saúde) e PubMed (Medline). A busca dos artigos foi restringida entre 2009 e 2019. Foi elaborada uma estratégia de busca na língua portuguesa e inglesa para cada uma das bases de dados pesquisadas, utilizando os seguintes descritores da área da saúde: Zika vírus, microcephaly e pathogenesis. Os descritores estão de acordo com o Medical Subject Headings (MeSH) e Descritores em Ciências da Saúde (DeCS). Com base na revisão realizada, a infecção por ZIKAV durante a gravidez parece ser a causa de um padrão reconhecível de anomalias congênitas que é consistente e ímpar, embora haja muitos componentes similares em outras infecções congênitas há algumas características que a difere, entre elas microcefalia grave com crânio parcialmente colapsado, córtex cerebral com calcificações subcorticais, cicatrização macular e mancha retiniana pigmentar, contraturas congênitas, e hipertonia precoce com sintomas de envolvimento extrapiramidal. A partir do fenótipo apresentado por essas crianças o tratamento determinado é individualizado sendo fundamental a neuroestimulação precoce para melhor espasticidade neuronal e possibilitar melhora da qualidade de vida desses recém-nascidos.
... Overexpression of the mutant protein in developing mouse brain resulted in aberrant neuronal migration and positioning 33 , while the presence of ectopic progenitors and defects in mitotic spindle orientation were observed in the embryonic cortex of E401K mutant mice but not of heterozygous knock-out mice 45 . These findings led to the hypothesis that the E401K variant acts through a complex dual mechanism where loss-of-function effects are associated to microcephaly while gain-of-function effects are linked to defective neuronal positioning and caused by undetected residual incorporation of the mutant protein into MTs or by a deleterious effect on the tubulin folding pathway 33,45 . ...
... Overexpression of the mutant protein in developing mouse brain resulted in aberrant neuronal migration and positioning 33 , while the presence of ectopic progenitors and defects in mitotic spindle orientation were observed in the embryonic cortex of E401K mutant mice but not of heterozygous knock-out mice 45 . These findings led to the hypothesis that the E401K variant acts through a complex dual mechanism where loss-of-function effects are associated to microcephaly while gain-of-function effects are linked to defective neuronal positioning and caused by undetected residual incorporation of the mutant protein into MTs or by a deleterious effect on the tubulin folding pathway 33,45 . We propose that reduced ciliation is due to the gainof-function mode of action of TUBB E401K and show that minimal (~2% of cells) incorporation of TUBB E401K into cellular MTs can occur, suggesting that the mutant protein is not intrinsically incapable of incorporating into MTs. ...
... We propose defective ciliogenesis to contribute to disease pathogenesis in at least a subset of TUBB-related tubulinopathy patients, alongside other cellular phenotypes associated with MT dysfunction such as the mitotic and spindle defects described for the E401K variant 45 . ...
Tubulinopathies and neurodevelopmental ciliopathies are two groups of genetic disorders characterized by abnormal brain development resulting in structural brain malformations. Tubulinopathies are caused by dominant missense mutations in genes encoding for tubulins, the building blocks of microtubules. Neurodevelopmental ciliopathies are mostly recessive disorders caused by defects in the function of the primary cilium, a sensory organelle that modulates signaling pathways important for brain development. Though more than 40 genes have been associated with neurodevelopmental ciliopathies, many patients still do not have an identified genetic etiology. Herein, we present a novel de novo heterozygous missense variant in Tubulin Beta Class I ( TUBB ) identified through whole-genome sequencing analysis in a patient with both ciliopathy and tubulinopathy brain features. While microtubules are fundamental to primary cilia formation and function, no association between mutations in tubulin genes and neurodevelopmental ciliopathies has been found to date. Using patient-derived cells and gene-edited isogenic cell lines, we show that the identified variant impairs the early stages of cilia formation by altering microtubule dynamics and structure. Furthermore, we demonstrate that the disease mechanism is not haploinsufficiency and that other patient mutations in TUBB affect cilia formation in vitro , putting forward defective ciliogenesis as a contributing pathogenic factor in a subset of tubulinopathy patients.
... Additionally, it was also shown that the mutant Tubb5 could disturb the migration process due to altered chaperone mediated tubulin folding and altered microtubule dynamics. Tubb5 is shown to be involved in neuronal differentiation as they also play a role during dendritic spine formation [102,104,105]. Together, these investigations indicate that TUBB is associated with the functions like neuronal proliferation, radial migration of neurons and even in maintaining skin morphology. ...
Tubulins are the highly conserved subunit of microtubules which involve in various fundamental functions including brain development. Microtubules help in neuronal proliferation, migration, differentiation, cargo transport along the axons, synapse formation, and many more. Tubulin gene family consisting of multiple isotypes, their differential expression and varied post translational modifications create a whole new level of complexity and diversity in accomplishing manifold neuronal functions. The studies on the relation between tubulin genes and brain development opened a new avenue to understand the role of each tubulin isotype in neurodevelopment. Mutations in tubulin genes are reported to cause brain development defects especially cortical malformations, referred as tubulinopathies. There is an increased need to understand the molecular correlation between various tubulin mutations and the associated brain pathology. Recently, mutations in tubulin isotypes (TUBA1A, TUBB, TUBB1, TUBB2A, TUBB2B, TUBB3, and TUBG1) have been linked to cause various neurodevelopmental defects like lissencephaly, microcephaly, cortical dysplasia, polymicrogyria, schizencephaly, subcortical band heterotopia, periventricular heterotopia, corpus callosum agenesis, and cerebellar hypoplasia. This review summarizes on the microtubule dynamics, their role in neurodevelopment, tubulin isotypes, post translational modifications, and the role of tubulin mutations in causing specific neurodevelopmental defects. A comprehensive list containing all the reported tubulin pathogenic variants associated with brain developmental defects has been prepared to give a bird’s eye view on the broad range of tubulin functions.
... Despite the diverse genetic causes, microcephaly phenotypes often converge to trigger p53 activation and apoptosis in dividing RGPs and/or nascent neurons. In such cases, genetic deletion of Trp53 rescues the microcephaly phenotype (41)(42)(43)(44). We noted the presence of p53-related GO terms in several modules of the STRING network (data table S1). ...
The generation of a correctly sized cerebral cortex with all-embracing neuronal and glial cell-type diversity critically depends on faithful radial glial progenitor (RGP) cell proliferation/differentiation programs. Temporal RGP lineage progression is regulated by Polycomb repressive complex 2 (PRC2), and loss of PRC2 activity results in severe neurogenesis defects and microcephaly. How PRC2-dependent gene expression instructs RGP lineage progression is unknown. Here, we use mosaic analysis with double markers (MADM)-based single-cell technology and demonstrate that PRC2 is not cell-autonomously required in neurogenic RGPs but rather acts at the global tissue-wide level. Conversely, cortical astrocyte production and maturation is cell-autonomously controlled by PRC2-dependent transcriptional regulation. We thus reveal highly distinct and sequential PRC2 functions in RGP lineage progression that are dependent on complex interplays between intrinsic and tissue-wide properties. In a broader context, our results imply a critical role for the genetic and cellular niche environment in neural stem cell behavior.
... Furthermore, a number of reports suggest that induction of p53 protein in the developing brain, by suppressing the expression of negative regulators of p53 protein stability, induces apoptosis and cell cycle arrest in the progenitor cells, leading to microcephaly . [39][40][41][42][43][44][45][46] Similarly, our data suggest that Rnf113a1 knockdown stabilizes p53 protein expression, and promotes a proapoptotic and anti-proliferation phenotype in NSCs, while loss-of-function mutations in the RNF113A gene cause a microcephaly phenotype in humans. It is therefore tempting to propose that p53 may mediate, at least partially, these effects of Rnf113a1 on the mammalian brain. ...
RNF113A (Ring Finger Protein 113A) is genetically associated with autism spectrum disorders and X-linked trichothiodystrophy (TTD) syndrome. Loss-of-function mutations in human RNF113A are causally linked to TTD, which is characterized by abnormal development of central nervous system (CNS) and mental retardation. How loss of RNF113A activity affects brain development is not known. Here we identify Rnf113a1 as a critical regulator of cell death and neurogenesis during mouse brain development. Rnf113a1 gene exhibits widespread expression in the embryonic CNS. Knockdown studies in embryonic cortical neural stem/progenitor cells (NSCs) and the mouse cortex suggest that Rnf113a1 controls survival, proliferation and differentiation properties of progenitor cells. Importantly, Rnf113a1 deficiency triggers cell apoptosis via a combined action on essential regulators of cell survival, including p53, Nupr1 and Rad51. Collectively, these observations establish Rnf113a1 as a regulatory factor in CNS development and provide insights for its role in neurodevelopmental defects associated with TTD and autism.
... Despite the diverse genetic causes, microcephaly phenotypes often converge to trigger p53 activation and apoptosis in dividing RGPs and/or nascent neurons. In such cases genetic deletion of Trp53 rescue the microcephaly phenotype (Bianchi et al., 2017;Breuss et al., 2016;Houlihan and Feng, 2014;Little and Dwyer, 2019;Mao et al., 2016;Marjanovic et al., 2015;Phan et al., 2021). ...
... The core modules encompass proliferation-associated genes. Many primary microcephaly mutants show a strong mechanical impairment of cell division (defective assembly of the mitotic spindle or centromere attachment) (Bianchi et al., 2017;Breuss et al., 2016;Keil et al., 2020;Little and Dwyer, 2019;Mao et al., 2016;Marino et al., 2000;Marjanovic et al., 2015;Nechiporuk et al., 2016;Phan et al., 2021) and a strong correlation between cell cycle mechanisms involved in DNA integrity, mitotic checkpoints and . CC-BY-NC-ND 4.0 International license available under a was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. ...
... Based on genetic epistasis experiments we demonstrated that diminished RGP proliferation and associated microcephaly in Eed cKO mice could not be rescued by concomitant loss of Trp53. These findings point towards a Trp53-independent mechanism and are insofar intriguing since other gene mutations affecting cell cycle progression trigger microcephaly in a Trp53-dependent manner (Bianchi et al., 2017;Breuss et al., 2016;Keil et al., 2020;Little and Dwyer, 2019;Mao et al., 2016;Marino et al., 2000;Marjanovic et al., 2015;Nechiporuk et al., 2016;Phan et al., 2021). Given that the global mutant cellular landscape in cKO-Eed-MADM mice is the main driver of microcephaly, it is likely that the brain size alteration due to wholetissue loss of PRC2 activity involves a complex aggregation or interplay of environmental cues and cell-intrinsic transcriptional responses. ...
The generation of a correctly-sized cerebral cortex with all-embracing neuronal and glial cell-type diversity critically depends on faithful radial glial progenitor (RGP) cell proliferation/differentiation programs. Temporal RGP lineage progression is regulated by Polycomb Repressive Complex 2 (PRC2) and loss of PRC2 activity results in severe neurogenesis defects and microcephaly. How PRC2-dependent gene expression instructs RGP lineage progression is unknown. Here we utilize Mosaic Analysis with Double Markers (MADM)-based single cell technology and demonstrate that PRC2 is not cell-autonomously required in neurogenic RGPs but rather acts at the global tissue-wide level. Conversely, cortical astrocyte production and maturation is cell-autonomously controlled by PRC2-dependent transcriptional regulation. We thus reveal highly distinct and sequential PRC2 functions in RGP lineage progression that are dependent on complex interplays between intrinsic and tissue-wide properties. In a broader context our results imply a critical role for the genetic and cellular niche environment in neural stem cell behavior.
... Analysis of mouse lines harboring tubulin isotype gene mutations has been useful to model human disease phenotypes and to test the requirement of tubulin isotype genes (2). Knockout alleles of Tubb5 (37) and Tubb1 (17) show that these tubulin isotypes are essential for mouse development with the loss-of-function phenotypes resembling the human pathologies. However, deletion of other tubulin isotype genes in mice shows only minor defects that do not recapitulate the human disease phenotypes (38,39), indicating that certain tubulin isotype genes are functionally redundant in mice. ...
Mutations in tubulins cause distinct neurodevelopmental and degenerative diseases termed "tubulinopathies"; however, little is known about the functional requirements of tubulins or how mutations cause cell-specific pathologies. Here, we identify a mutation in the gene Tubb4a that causes degeneration of cerebellar granule neurons and myelination defects. We show that the neural phenotypes result from a cell type-specific enrichment of a dominant mutant form of Tubb4a relative to the expression other β-tubulin isotypes. Loss of Tubb4a function does not underlie cellular pathology but is compensated by the transcriptional up-regulation of related tubulin genes in a cell type-specific manner. This work establishes that the expression of a primary tubulin mutation in mature neurons is sufficient to promote cell-autonomous cell death, consistent with a causative association of microtubule dysfunction with neurodegenerative diseases. These studies provide evidence that mutations in tubulins cause specific phenotypes based on expression ratios of tubulin isotype genes.
... Symptoms in our patient are less severe as seen in patients with dominant negative missense mutations, most likely due to the fact that TUBB heterodimers can still form, albeit at reduced levels. Breuss and colleagues described heterozygous Tubb5 mice as having decreased brain volumes due to increased apoptosis [90]. Another study in mice showed that perturbations to TUBB5 have a deleterious effect on multiple aspects of neuronal differentiation (e.g. ...
Hirschsprung disease (HSCR) is a complex genetic disease characterized by absence of ganglia in the intestine. HSCR etiology can be explained by a unique combination of genetic alterations: rare coding variants, predisposing haplotypes and Copy Number Variation (CNV). Approximately 18% of patients have additional anatomical malformations or neurological symptoms (HSCR-AAM). Pinpointing the responsible culprits within a CNV is challenging as often many genes are affected. Therefore, we selected candidate genes based on gene enrichment strategies using mouse enteric nervous system transcriptomes and constraint metrics. Next, we used a zebrafish model to investigate whether loss of these genes affects enteric neuron development in vivo. This study included three groups of patients, two groups without coding variants in disease associated genes: HSCR-AAM and HSCR patients without associated anomalies (HSCR-isolated). The third group consisted of all HSCR patients in which a confirmed pathogenic rare coding variant was identified. We compared these patient groups to unaffected controls. Predisposing haplotypes were determined, confirming that every HSCR subgroup had increased contributions of predisposing haplotypes, but their contribution was highest in isolated HSCR patients without RET coding variants. CNV profiling proved that specifically HSCR-AAM patients had larger Copy Number (CN) losses. Gene enrichment strategies using mouse enteric nervous system transcriptomes and constraint metrics were used to determine plausible candidate genes located within CN losses. Validation in zebrafish using CRISPR/Cas9 targeting confirmed the contribution of UFD1L, TBX2, SLC8A1, and MAPK8 to ENS development. In addition, we revealed epistasis between reduced Ret and Gnl1 expression and between reduced Ret and Tubb5 expression in vivo. Rare large CN losses-often de novo-contribute to HSCR in HSCR-AAM patients. We proved the involvement of six genes in enteric nervous system development and Hirschsprung disease.
... It is possible that loss of RTTN produces structural and functional centriole aberrations, which perturbs the assembly of functional centrosomes (spindle poles) in mitotic cells, leading to multiple mitotic spindle defects, aneuploidy, apoptosis, and spindle misorientation. Furthermore, acentriolar mitosis frequently activates a p53-dependent apoptotic pathway [40][41][42][43][44][45]. Strikingly, a small portion of apoptotic cells (sub-G1, 5.6 ± 1.3%) was observed in RTTN −/− ; p53 −/− cells ( Figure 2D) in the absence of p53, implying that a p53-independent apoptosis occurred in RTTN-knockout cells. ...
Autosomal recessive primary microcephaly (MCPH) is a complex neurodevelopmental disorder characterized by a small brain size with mild to moderate intellectual disability. We previously demonstrated that human microcephaly RTTN played an important role in regulating centriole duplication during interphase, but the role of RTTN in mitosis is not fully understood. Here, we show that RTTN is required for normal mitotic progression and correct spindle position. The depletion of RTTN induces the dispersion of the pericentriolar protein γ-tubulin and multiple mitotic abnormalities, including monopolar, abnormal bipolar, and multipolar spindles. Importantly, the loss of RTTN altered NuMA/p150Glued congression to the spindle poles, perturbed NuMA cortical localization, and reduced the number and the length of astral microtubules. Together, our results provide a new insight into how RTTN functions in mitosis.
... codant pour une protéine associée au microtubules impliquée dans l'orientation du fuseau mitotique et la duplication des centrioles(Fujimori et al., 2014), et qui représente 68.6 % des cas de MCPH ; WDR62 (WD repeat-containing protein 62), localisé au locus 19q13.12, codant pour une protéine impliquée dans la voie de signalisation c-Jun et dans les fonctions du centrosome (Chen et al., 2014; Nicholas et al., 2010; Yu et al., 2010), et comptabilisant 14.1 % ; MCPH1, localisé au chromosome 8p23 et codant pour la Microcéphaline, impliqué dans la condensation de la chromatine et représentant 8 % des MCPH(Gruber et al., 2011;Jackson et al., 2002;Trimborn et al., 2004).De nombreux cas de microcéphalie touchent des patients portant des mutations dans les gènes codant pour les différents isoformes de la tubuline tels que TUBA1A(Myers et al., 2015), TUBB2B(Romaniello et al., 2012) et TUBB5(Breuss et al., 2016). Par ailleurs, les mutations dans les isoformes de la tubuline entraînent des MCDs au « large spectre », combinant plusieurs pathologies comme la microcéphalie, la polymicrogyrie, l'hypoplasie du cerveau, du cervelet et du pont cérébral(Figure 21).On qualifie les pathologies présentant des tableaux cliniques de tubulinopathies(Bahi-Buisson et al., 2014;Romero et al., 2018). ...
Les malformations du développement du cortex sont associées à des troubles de la prolifération des progéniteurs et de la migration neuronale. Les glies radiaires basales (bRGs), un type de progéniteur, sont limités dans les espèces lissencéphaliques mais abondants dans les cerveaux gyrencéphaliques. Le gène LIS1, codant pour un régulateur de la dynéine, est muté dans la lissencéphalie humaine. LIS1 a un rôle dans la division cellulaire et la migration neuronale. Dans cette étude, nous avons généré des cellules bRG-like dans le cerveau embryonnaire murin, pour étudier le rôle de Lis1 dans leur production. Ceci fut réalisé par électroporation in utero du gène hominoïde-spécifique TBC1D3 au jour embryonnaire (E) 14.5. Nous avons confirmé que l’expression de TBC1D3 dans des cerveaux WT induit un grand nombre de cellules bRG-like basales. Puis, nous avons étudié la production des bRGs-like dans des cerveaux murins hétérozygotes pour Lis1. Nos résultats novateurs montrent que la déplétion de Lis1 à partir de E9.5 empêche la production de cellules bRG-like induites par TBC1D3. La déplétion de Lis1 change l’orientation du fuseau mitotique, accroit le nombre de mitoses abventriculaires et altère l’expression de N-Cadhérine. Nous concluons que la perturbation du dosage de Lis1 pourrait perturber le nombre et la position corrects des progéniteurs, contribuant à la pathogenèse de Lis1.
