Centrosomal Proteins And Neuronal Migration: Physiological And Pathological Roles Of Cep41.
Reference : PhD Juliette GODIN
Offer publication : April 5, 2016
The cerebral cortex contains neurons that are distributed within layers and are regionally organized into specialized areas that underlie sophisticated motor, cognitive and perceptual abilities. Cortical lamination follows an “inside-out” sequence of neuronal placement and maturation that arises from the successive birth and orderly migration of glutamatergic projection neurons born in the dorsal telencephalon and GABAergic interneurons originating in the ganglionic eminences. The development of the cortex progresses through several stages, including neuronal
proliferation, migration and differentiation. These concurrent steps imply establishment of cell polarity, which largely depends on the dynamic regulation of the centrosome (CTR), the major microtubule organizer. Importantly, mutations in centrosomal proteins have been genetically linked to several brain disorders such as microcephaly, dwarfism, lisencephaly and ciliopathies. Thus, identification of new centrosomal regulators is essential
to shed more light on the molecular mechanisms responsible for the generation of fully differentiated cortical neurons. Projection neurons are born in the dorsal telencephalon and migrate a short distance along radial glia fibers to settle in dedicated cortical layers. At the onset of corticogenesis, projection neurons reach their final destination by somal translocation, and as the cortical wall thickens, neurons move by locomotion on radial glia fibers. Migrating neurons undergo major morphological changes that are accompanied by dramatic shifts in cytoskeleton
structure and CTR positioning. In migrating multipolar neurons, CTR is located at the base of the growing axon. At the multipolar-bipolar transition, CTR reorients towards the pia-directed leading process, where it is coupled to the nucleus and where it exerts pulling forces to drive forward nuclear translocation in locomoting bipolar neurons. Very interestingly, some brain malformations that arise from impaired migration such as pachygyria,
lissencephaly or polymicrogyria have been associated with mutation in centrosomal proteins. Centrosomales proteins could therefore have crucial roles during migration.
The major goal of the current project is to better characterize the centrosome-regulated cellular and molecular pathways that contribute to projection
neurons radial migration in health and disease. We will adopt a candidate-based approach and describe the function of a neurodevelopmental disorders-related centrosomal protein, CEP41, in health and autism conditions. The project aims to 1) investigate whether and how CEP41 controls the migration of projection neuron; and 2) analyze the physiological consequences of CEP41 pathologies-associated mutations.
To assess CEP41 functions in radial migration, we will conditionally delete CEP41 from postmitotic neurons by crossing CEP41 lox mice Nex-Cre mice or by in utero electroporation of NeuroD-CRE-iGFP in lox embryos. We will determine whether CEP41 depletion affects: 1) the morphology
(multipolar/bipolar stage; attachment to the pia); 2) the distribution (at E14; E18 and postnatal (P) day 2); 3) the dynamic migration (time lapse recordings on cortical slices) of projection neurons; and 4) the dynamic positioning of CTR during radial migration (In utero electroporation of centrinII-RFP plasmids together with NeuroD-CRE-iGFP combined with time lapse recordings). To assess the effect of CEP41 mutations (variants
associated with autism), we will perform rescue experiments using wt- or mutated CEP41. To identify the molecular mechanisms underlying CEP41 function in tangential migration, this project will benefit from a BioID screen that have been performed in the lab and we will further analyze the most
promising CEP41 partners regarding their known function in radial migration.
- WISHED SKILLS : Background in neurobiology, and skills in molecular and/or cell biology, imaging, Knowledge of cortical development or cytoskeleton field
- EXPERTISES WHICH WILL BE ACQUIRED DURING THE TRAINING : In vivo mouse techniques (in utero electroporation),
Imaging techniques (time lapse recording- confocal microscopy),
Mouse work Organotypic brain slices –cell culture,
Molecular cloning Biochemistry (immunoprecipitation- Western Blotting), Expertise in cortical development, neuronal migration, centrosome, cytoskeleton, Training in oral communication (data and journal club – posters), Develop ability to analyze and synthetize, Teamwork, collaboration
Application Deadline : Dec. 31, 2016