The Reelin gene located on the human chromosome region 7q22, encodes an extracellular matrix glycoprotein, a ligand for ApoER2 and low-density lipoprotein receptors (LDL) Receptor, is required for mediating the correct positioning of neurons during embryonic brain development1. In the current study, first we applied RT-PCR and immunohistochemistry analysis (IHC) analysis on tissue microarrays (TMA) to verify the Reelin expression patterns in a variety of adult tissues, suggesting additional roles for Reelin in stabling the cyto-architecture and controlling the remodeling of many organs during development. Second, we report the Reelin expression status in tumorigenesis. We discover that the loss of Reelin expression is associated with multiple types of cancers, including more than 80% of both breast and colorectal cancers. Interestingly, our study also found suspension small cell lung cancer (SCLC) cell lines that grow as large aggregates retained high Reelin expression, whereas attached non small cell lung cancer cultures do not. That may imply the Reelin expression may be also associated with cell culture morphology and growth characteristics in the in vitro culture system for lung cancers. Our results here also demonstrated that epigenetic silencing of Reelin expression by DNA hypermethylation in tumors directly correlates with loss of Reelin expression in many cancers. Reelinmethylation was reversed and expression restored by treating tumor cell lines with the demethylating agent 5-aza-2-deoxycytidine. In conclusion, from the molecular basis of Reelingene inactivation in human cancer here, we propose that the Reelinvariation in more than 80% of breast and colorectal cancers makes it a significant novel tumor marker.

No description available.

No description available.

<p>Autism is a pervasive developmental disorder (PDD) that&rsquo / s incidence is approximately 1 in 158. It is four times more prevalent in males than females and is believed to be caused by both genetic and environmental factors. Research indicates that several genes are involved in autism and it is believed that these genes act together to produce autism. Many genes implicated in this disorder are involved with brain structure formation and brain functioning. Studies have identified the reelin (RELN) gene as necessary for proper formation of brain, which indicates that RELN abnormalities could contribute to the aetiology of several neurogenetic diseases such as schizophrenia, bipolar and autism. The aims of the study were (i) to genotype two SNPs (exonic rs3622691 and intronic rs736707) in the RELN gene using Taqman&reg / SNP Genotyping assays to detect association with autism in three distinct South African (SA) ethnic groups (Black, Caucasian and Mixed), and (ii) to detect candidate genes that are over and under-expressed in the samples taken from a SA Caucasian autistic group and compare those with samples taken from a healthy Caucasian group using cDNA microarray. The Taqman&reg / study indicated significant association for the intronic SNP, rs736707, with a p-value of 0.0009 in the total SA group. More so, the Mixed group displayed the highest significance amongst the ethnic groups, with a p-value of 0.00014. The microarray study yielded 21 genes with 95% significance in the Caucasian sample group. Most genes were hypothetical proteins and formed part of the FAM90A family. The LOC83459 showed the highest level of expression in the autistic samples, while the BTNL8 gene was shown to be highly suppressed in the control samples.</p>

Magister Scientiae - MSc / Autism is a pervasive developmental disorder (PDD) that's incidence is approximately 1 in 158. It is four times more prevalent in males than females and is believed to be caused by both genetic and environmental factors. Research indicates that several genes are involved in autism and it is believed that these genes act together to produce autism. Many genes implicated in this disorder are involved with brain structure formation and brain functioning. Studies have identified the reelin (RELN) gene as necessary for proper formation of brain, which indicates that RELN abnormalities could contribute to the aetiology of several neurogenetic diseases such as schizophrenia, bipolar and autism. The aims of the study were (i) to genotype two SNPs (exonic rs3622691 and intronic rs736707) in the RELN gene using Taqman® SNP Genotyping assays to detect association with autism in three distinct South African (SA) ethnic groups (Black, Caucasian and Mixed), and (ii) to detect candidate genes that are over and under-expressed in the samples taken from a SA Caucasian autistic group and compare those with samples taken from a healthy Caucasian group using cDNA microarray. The Taqman® study indicated significant association for the intronic SNP, rs736707, with a p-value of 0.0009 in the total SA group. More so, the Mixed group displayed the highest significance amongst the ethnic groups, with a p-value of 0.00014. The microarray study yielded 21 genes with 95% significance in the Caucasian sample group. Most genes were hypothetical proteins and formed part of the FAM90A family. The LOC83459 showed the highest level of expression in the autistic samples, while the BTNL8 gene was shown to be highly suppressed in the control samples. / South Africa

The Reelin signaling pathway has been proven to play a critical role in human neural development, especially in the architectonic development of the central nervous system. Extracelltilar Reeiin binds to the Very Low Density Lipoprotein Receptor (VLDLR) or the Apolipoprotein -E Receptor Type 2 (ApoER2) on the neural cell membrane and then induces tyrosine phosphorylation· o( the adapter protein Disabled - 1 (Dab-1 ). The phosphorylated Dab-I then cross talk with Wnt pathway to regulate gene expression. Recent researches have shown the Reelin pathway, or more specifically, Dab 1 over expression inhibits Glycogen Synthase Kinase 3P (GSK-3P) of the Wnt pathway. Taken the effect that inhibition of GSK-3P frees and promotes the P-Catenin acumination in cell cytosol and nucleus, and demonstrated by recent researches, increased level of neuron differentiation of GSK-3 p inhibited cell, we suggest that Dab-1 's ability of inhibit GSK- 3P will also result in increase level of P-Catenin in the human neural stem cells (HNSC), thus inducing the HNSC cells to differentiate. Testing the HNSC cells separately with Reelin conditioned media treatment and Dab-1 over-expression show significant increasing of acumination of P-Catenin in cell nucleus. Furthermore, demonstrated by our studies, Dab-1 over-expression also increases the neuron differentiation in HNSCs.

No description available.

O transtorno do espectro do autismo (TEA) constitui um grupo heterogêneo e altamente prevalente de doenças do neurodesenvolvimento. Análises genômicas recentes têm revelado um grande número de variantes genéticas potencialmente deletérias nos pacientes com TEA, a maioria rara ou privada. Um enorme desafio atual é determinar quais dentre essas variantes são as que de fato estão envolvidas na etiologia do transtorno nos pacientes, e quantas variantes patogênicas são necessárias para a penetrância completa do TEA em cada paciente. Recentemente, por meio do sequenciamento completo do exoma de um subgrupo de pacientes com TEA não-sindrômico - nos quais observamos hiperfuncionamento da via de sinalização intracelular mTORC1 - identificamos que um dos pacientes (referido como F2688) é heterozigoto composto para variantes de substituição de aminoácidos raras e potencialmente deletérias no gene ELN. Este gene codifica Relina, uma grande glicoproteína de matriz extracelular que, por meio da ativação da proteína Dab1 e de diferentes vias de sinalização intracelular, controla a migração e o posicionamento dos neurônios, a arborização de neuritos, e o funcionamento das sinapses em várias regiões do encéfalo, tanto no desenvolvimento embrionário como na vida adulta. Estudos anteriores já haviam descrito variantes em heterozigose potencialmente de perda de função no gene RELN em pacientes com TEA; contudo, nenhum desses estudos investigou disfunção da sinalização Relina-Dab1 nos pacientes e, portanto, os efeitos moleculares e celulares de tais variantes sobre células neurais humanas ainda são poucos explorados. Neste trabalho, utilizando células neuroprogenitoras (NPCs) derivadas de células-tronco pluripotentes induzidas do paciente F2688, de outros pacientes com TEA sem mutação em RELN (n=5) e de indivíduos controles (n=5), nós descrevemos que as NPCs do paciente F2688 apresentam: i) disfunção da via de sinalização Relina-Dab1; ii) hiperfuncionamento da via de sinalização mTORC1; iii) crosstalk anormal entre as vias de sinalização Relina-Dab1 e mTORC1, o qual é atenuado com o uso da rapamicina, um inibidor específico de mTORC1. Portanto, nossos resultados sugerem, pela primeira vez, uma relação anormal entre as vias de sinalização Relina-Dab1 e mTORC1 em TEA não-sindrômico / Autism Spectrum Disorder (ASD) is a heterogeneous and highly prevalent group of neurodevelopmental disorders. Whole-genome-based approaches have generated catalogues of thousands of rare and potentially deleterious genetic variants in ASD patients. However, the challenge now is to identify genuine disease-causing/risk variants among the multitude of variants discovered in each exome/genome and how many variants are required to cause the disease. Recently, we performed whole-exome sequencing in a subgroup of ASD patients - in whom we found mTORC1 signaling hyperfunction - and identified rare and potentially deleterious compound heterozygous variants in the RELN gene in one patient (called as F2688). The RELN gene encodes Reelin, a large secreted glycoprotein that controls neuronal migration, layer formation, neurite outgrowth, and plasticity of synapses in both the developing and the adult brain. Evidence from previous studies suggests that certain potential loss-of-function variants in RELN gene can contribute to ASD susceptibility; however, few studies today have directly demonstrated impairment of the Reelin signal transduction cascade in ASD patients and therefore, the molecular and cellular effects of these variants in human neuronal cells are still poorly explored. Here, by using induced pluripotent stem cells derived neuronal progenitor cells from F2688 patient, from other ASD patients who do not carry RELN disrupting variants (n=5) and from control individuals (n=5), we have demonstrated that F2688-derived NPCs show: i) impaired Reelin-Dab1 signaling; ii) overactive mTORC1 signaling; iii) and abnormal crosstalk between mTORC1 and Reelin-Dab1 signaling pathways, which it attenuated by rapamycin (a specific mTORC1 inhibitor). Taken together, our results point to an abnormal interplay between mTORC1 and Reelin-Dab1 networks in nonsyndromic ASD

Les connexions neuronales du système visuel forment des synapses spatialement distribuées en couches discrètes. Comprendre la base du ciblage spécifique axonale est critique pour déchiffrer la formation des réseaux neuronaux complexes. Dans une première étude, nous avons investigué le rôle de la protéine de la matrice extracellulaire Reelin dans la formation in vivo du circuit rétinotectal chez le poisson zèbre. Ce circuit se compose de cellules ganglionnaires de la rétine (CGRs) transmettant l’information visuelle au cerveau via la projection de leur axone dans les différentes couches du tectum optique. Nous avons démontré que la Reelin secrétée par de neurones inhibiteurs localisés dans les couches supérieures du tectum optique forme un gradient. L’induction de mutations délétères dans la voie de signalisation canonicale de la Reelin à l’aide d’outils génétiques a conduit à des défauts de ciblage des axones de CGRs. Nos résultats démontrent un nouveau rôle de la Reelin lors du développement du système visuel et la décrivent comme signature moléculaire nécessaire au ciblage et au positionnement précis des axones de CGRs.Dans une seconde étude, nous avons utilisé la technique CRISPR/Cas9 pour développer une nouvelle approche de mutagénèse conditionnelle chez le poisson zèbre. Nos résultats démontrent que la perturbation de gènes dans des tissues spécifiques peut être effectué par l’induction de l’expression de la protéine Cas9 via le système Gal4/UAS. Nous avons établis un outil pour induire l’apparition de mutations délétères dans des clones de cellules mais aussi dans des cellules individuelles, tous pouvant être suivit distinctement grâce à un marquage génétique. / Neuronal connections in the visual system are arranged in synaptic laminae. Understanding the basis of lamina-specific axonal targeting is critical to gain deeper insights on how complex neural networks form. In a first study we investigated the role of the ECM protein Reelin during zebrafish retinotectal circuit formation in vivo. Here retinal ganglion cells (RGCs) convey the visual information to the brain by projecting their axons to different layers of the optic tectum. We demonstrated that Reelin secreted by a specific class of tectal superficial inhibitory neurons is spatially distributed in a superficial-to-deep gradient within the tectal neuropil. Induced gene disruption for all the components of the canonical Reelin pathway expressed in the retinotectal system resulted in aberrant layering of RGC axons suggesting a role for Reelin pathway in axonal sublaminar segregation. Altogether our findings elucidate a new role for Reelin in vertebrate visual system development, during which it acts as molecular cue by imparting positional information for ingrowing RGCs.In a second study we took advantage of the CRISPR/Cas9 technology to develop a novel approach for conditional mutagenesis in zebrafish. Our results provide evidence that tissue-specific gene disruption can be achieved by driving Cas9 expression with the Gal4/UAS system. We established a tool to induce loss-of-function mutations in cell clones or single cells that can be followed by genetic labeling, enabling their phenotypic analysis. Our technique has the potential to be applied to a wide-range of model organisms, allowing systematic mutagenesis and labeling on a genome-wide scale.

La pathogénèse de désordres psychiatriques comme les troubles de l'humeur et la schizophrénie met en jeu des facteurs génétiques et environnementaux. La reelin, une protéine de la matrice extracellulaire et l'isolement social (IS), un stress environnemental participeraient à l'étiologie de ces maladies. Le cortex préfrontal (CPF) impliqué dans les fonctions cognitives et exécutives, présente des anomalies morpho-fonctionnelles chez les patients atteints de ces troubles. Le but de ma thèse est d'étudier l'effet de l'IS et d'une haplo-insuffisance en reelin (HIR) sur les propriétés du CPF adulte. Nous utilisons des souris hétérozygotes reelin et sauvages soumises à l'IS et procédons à une analyse électrophysiologique, morphologique et comportementale. Nos résultats montrent que l'IS induit des défauts de transmission et de plasticité synaptique et du comportement. Nous avons également montré que l'HIR aggrave ces défauts. Finalement, nous avons exploré une piste thérapeutique prometteuse. / The pathogenesis of psychiatric disorders such as mood disorders and schizophrenia involves genetic and environmental factors. The reelin, a protein of the extracellular matrix and social isolation (SI), an environmental stress participate in the etiology of these diseases. The prefrontal cortex (PFC) involved in cognitive and executive functions, exhibits morpho-functional abnormalities in patients with these disorders. The purpose of my thesis is to study the effect of the SI and a haploinsufficiency in reelin (HIR) on the properties of the adult PFC. We used wild mice and reelin heterozygous mice that underwent and proceed to electrophysiological, morphological and behavioral analyses. Our results show that the SI altered synaptic transmission and plasticity and behavior. We also showed that the HIR aggravates these alterations. Finally, we explored a promising therapy.