Project description:Malformations of cortical development (MCD) are present in up to 40% of children with pharmacoresistant epilepsy. Although epilepsy surgery can be successful in a subset of children, not all forms of MCD are operable. Understanding the genetic and neurobiological mechanisms underlying MCD and MCD-related epilepsy are necessary for the development of novel anti-epilepsy drugs. The tish (telencephalic internal structural heterotopia) rat is a unique model of MCD and spontaneous seizures, but the underlying genetic mutation has been, heretofore, unknown. DNA and RNA-sequencing revealed that a deletion encompassing a previously unannotated exon markedly diminished EML1 transcript and protein abundance in the tish brain. Developmental electrographic characterization of the tish rat demonstrated spontaneous spike-wave discharge (SWD) bursts beginning as early as postnatal day (P) 17. A dihybrid cross demonstrated that the mutantEml1 allele segregates with the observed dysplastic cortex and SWD bursts in monogenic autosomal recessive frequencies. Our data link the development of the bilateral, heterotopic dysplastic cortex of the tish rat to a mutation in Eml1 and provide a novel rat model of MCD.
Project description:Neuronal migration disorders such as lissencephaly and subcortical band heterotopia (SBH) are associated with epilepsy and intellectual disability. Doublecortin (DCX), LIS1 and alpha1-tubulin (TUBA1A), are mutated in these disorders, however corresponding mouse mutants do not show heterotopic neurons in the neocortex. On the other hand, the spontaneously arisen HeCo mouse mutant displays this phenotype. The study of this model reveals novel mechanisms of heterotopia formation. While, HeCo neurons migrate at the same speed as WT, abnormally distributed dividing progenitors were found throughout the cortical wall from E13. Through genetic studies we identified Eml1 as the mutant gene in HeCo mice. No full length transcripts of Eml1 were identified due to a retrotransposon insertion in an intron. Re-expression of Eml1, coding for a microtubule-associated protein, rescues the HeCo progenitor phenotype. We further show that EML1 is mutated in giant ribbon-like heterotopia in human. Our data link abnormal spindle orientations, ectopic progenitors and severe heterotopia in mouse and human. 16 samples analyzed corresponding to 8 wild type brain and 8 HeCo mutant brain
Project description:Neuronal migration disorders such as lissencephaly and subcortical band heterotopia (SBH) are associated with epilepsy and intellectual disability. Doublecortin (DCX), LIS1 and alpha1-tubulin (TUBA1A), are mutated in these disorders, however corresponding mouse mutants do not show heterotopic neurons in the neocortex. On the other hand, the spontaneously arisen HeCo mouse mutant displays this phenotype. The study of this model reveals novel mechanisms of heterotopia formation. While, HeCo neurons migrate at the same speed as WT, abnormally distributed dividing progenitors were found throughout the cortical wall from E13. Through genetic studies we identified Eml1 as the mutant gene in HeCo mice. No full length transcripts of Eml1 were identified due to a retrotransposon insertion in an intron. Re-expression of Eml1, coding for a microtubule-associated protein, rescues the HeCo progenitor phenotype. We further show that EML1 is mutated in giant ribbon-like heterotopia in human. Our data link abnormal spindle orientations, ectopic progenitors and severe heterotopia in mouse and human.
Project description:Spinal cord injury disrupts ascending and descending neural signals causing sensory and motor dysfunction below the injury. Neuromodulation with electrical stimulation is used in both clinical and research settings to induce neural plasticity and improve functional recovery following injury. However, the mechanisms by which electrical stimulation affects recovery remain unclear. In this study we examined the effects of cortical electrical stimulation following injury on transcription at several levels of the central nervous system. We performed a unilateral cervical spinal contusion injury in rats and delivered stimulation for one week to the contralesional motor cortex to activate a descending motor tract.RNA was purified from bilateral subcortical white matter, and 3 levels of the spinal cord. Here we provide the complete data set in the hope that it will be useful for researchers studying electrical stimulation as a therapy to improve recovery from the deficits associated with spinal cord injury.
Project description:Echinoderm microtubule (MT)-associated protein-like 1 (Eml1) is mutated in the HeCo mouse, which exhibits subcortical band heterotopia (SBH), a developmental malformation of the cerebral cortex. EML1 mutations are also found in human patients affected by severe ribbon-like heterotopia, associated with epilepsy and intellectual disability (1). Neural progenitors in the ventricular zone (VZ) of the developing cerebral cortex undergo precisely regulated divisions, and mitotic perturbations contribute to pathological mechanisms (2). Eml1 is expressed in the mouse VZ and ectopic progenitors are present in the mutant developing cortex, when Eml1 is absent, at early stages of development (1). Thus, Eml1 is likely to play a role in neural progenitors during cortical development. We performed cell and molecular biology assays aiming to elucidate the function of Eml1 in neural progenitors, and explored the VZ of the HeCo mutant in order to find morphological perturbations that might explain the initiation of SBH formation (3). As part of this study, we searched for Eml1 molecular partners by pull-downs from mouse cortical extracts at embryonic day E13.5 and mass spectrometry (MS) analyses in order to identify the molecular pathways in which the protein is involved (3). Eml1 is formed by an N-terminal region that contains a dimerization domain and a C-terminal region that forms a ‘tandem atypical propeller in EMLs’ (TAPE) domain. The isolated N-terminal domain strongly binds MTs, while the C-terminal domain preferentially binds tubulin, and its beta-propeller structure is thought also to mediate the interaction with other molecules (4,5). We focused for this study on the N-terminal part of the protein (amino acids 1-178). Future study will validate or elucidate new interactions by using the C-terminal domain and/or the full-length protein. The results obtained from the N terminal MS data, integrated with other experimental findings, allow us to insert Eml1 in a network of proteins that are likely to regulate the assembly and function of the mitotic spindle in neural progenitors (3). More precisely, we showed that the protein regulates MT dynamics and its loss leads to perturbations in metaphase spindle length, which in turn impact progenitor morphology and behavior (3). References 1. Kielar, M., et al. Mutations in Eml1 lead to ectopic progenitors and neuronal heterotopia in mouse and human. Nat. Neurosci. 17, 923–933 (2014). 2. Bizzotto, S., & Francis, F. Morphological and functional aspects of progenitors perturbed in cortical malformations. Front Cell Neurosci. 9, 30; 10.3389/fncel00030 (2015). 3. Bizzotto, S., et al. Eml1 loss impairs apical progenitor spindle length and soma shape in the developing cerebral cortex. 4. Richards, M. W., et al. Crystal structure of EML1 reveals the basis for Hsp90 dependence of oncogenic EML4-ALK by disruption of an atypical β-propeller domain. Proc. Natl. Acad. Sci. U.S.A. 111, 5195–5200 (2014). 5. Richards, M. W., et al. Microtubule association of EML proteins and the EML4-ALK variant 3 oncoprotein require an N-terminal trimerization domain. Biochem. J. 467, 529–536 (2015).
Project description:The cerebral cortex is a highly organized structure whose development depends on different progenitor cell types. These give rise to post-mitotic neurons that migrate across the developing cortical wall to their final positions in the cortical plate. Apical radial glia cells (aRGs) are the main progenitor type in early corticogenesis, responsible for the production of other progenitors, and regulating the final neuronal output. Abnormal behavior of aRG can severely impact corticogenesis resulting in cortical malformations. Mutations in the microtubule associated protein Eml1 lead to severe subcortical heterotopia, characterized by the presence of aberrantly located neurons beneath the normotopic cortex. Mutations in EML1/Eml1 have been reported in three families presenting severe atypical heterotopia, as well as in the Heterotopic cortex ‘HeCo’ spontaneous mouse mutant. In the latter, ectopically cycling aRGs were found cycling outside their normal proliferative ventricular zone (VZ) from early stages of corticogenesis (Croquelois et al., 2009, Kielar et al., 2014, Shaheen et al., 2017). Ectopic aRGs are likely to be responsible for the formation of the heterotopia. It is thus crucial to understand the role of Eml1 in aRGs to elucidate the physiological and pathological mechanisms causing aRGs to leave the VZ. The role of Eml1 in aRGs remains vastly unexplored. We have thus performed mass spectrometry with embryonic cortex lysates (E13.5) to shed light on the intracellular pathways and molecular mechanisms in which Eml1 could be involved. This data combined with other cell biology and biochemistry approaches will contribute to understand the role of this heterotopia protein at early stages of development.
Project description:Our study presents the first transcriptomic analyses for the urethral bilateral region. Our data shows the sexually dimorphic genes and gene expression behavior by MafB.