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Toudji I, Toumi A, Chamberland É, Rossignol E. Interneuron odyssey: molecular mechanisms of tangential migration. Front Neural Circuits 2023; 17:1256455. [PMID: 37779671 PMCID: PMC10538647 DOI: 10.3389/fncir.2023.1256455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/21/2023] [Indexed: 10/03/2023] Open
Abstract
Cortical GABAergic interneurons are critical components of neural networks. They provide local and long-range inhibition and help coordinate network activities involved in various brain functions, including signal processing, learning, memory and adaptative responses. Disruption of cortical GABAergic interneuron migration thus induces profound deficits in neural network organization and function, and results in a variety of neurodevelopmental and neuropsychiatric disorders including epilepsy, intellectual disability, autism spectrum disorders and schizophrenia. It is thus of paramount importance to elucidate the specific mechanisms that govern the migration of interneurons to clarify some of the underlying disease mechanisms. GABAergic interneurons destined to populate the cortex arise from multipotent ventral progenitor cells located in the ganglionic eminences and pre-optic area. Post-mitotic interneurons exit their place of origin in the ventral forebrain and migrate dorsally using defined migratory streams to reach the cortical plate, which they enter through radial migration before dispersing to settle in their final laminar allocation. While migrating, cortical interneurons constantly change their morphology through the dynamic remodeling of actomyosin and microtubule cytoskeleton as they detect and integrate extracellular guidance cues generated by neuronal and non-neuronal sources distributed along their migratory routes. These processes ensure proper distribution of GABAergic interneurons across cortical areas and lamina, supporting the development of adequate network connectivity and brain function. This short review summarizes current knowledge on the cellular and molecular mechanisms controlling cortical GABAergic interneuron migration, with a focus on tangential migration, and addresses potential avenues for cell-based interneuron progenitor transplants in the treatment of neurodevelopmental disorders and epilepsy.
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Affiliation(s)
- Ikram Toudji
- Centre Hospitalier Universitaire (CHU) Sainte-Justine Research Center, Montréal, QC, Canada
- Department of Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - Asmaa Toumi
- Centre Hospitalier Universitaire (CHU) Sainte-Justine Research Center, Montréal, QC, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC, Canada
| | - Émile Chamberland
- Centre Hospitalier Universitaire (CHU) Sainte-Justine Research Center, Montréal, QC, Canada
- Department of Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - Elsa Rossignol
- Centre Hospitalier Universitaire (CHU) Sainte-Justine Research Center, Montréal, QC, Canada
- Department of Neurosciences, Université de Montréal, Montréal, QC, Canada
- Department of Pediatrics, Université de Montréal, Montréal, QC, Canada
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Halász P, Szũcs A. Self-limited childhood epilepsies are disorders of the perisylvian communication system, carrying the risk of progress to epileptic encephalopathies-Critical review. Front Neurol 2023; 14:1092244. [PMID: 37388546 PMCID: PMC10301767 DOI: 10.3389/fneur.2023.1092244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 04/04/2023] [Indexed: 07/01/2023] Open
Abstract
"Sleep plasticity is a double-edged sword: a powerful machinery of neural build-up, with a risk to epileptic derailment." We aimed to review the types of self-limited focal epilepsies..."i.e. keep as two separate paragraphs" We aimed to review the types of self-limited focal epilepsies: (1) self-limited focal childhood epilepsy with centrotemporal spikes, (2) atypical Rolandic epilepsy, and (3) electrical status epilepticus in sleep with mental consequences, including Landau-Kleffner-type acquired aphasia, showing their spectral relationship and discussing the debated topics. Our endeavor is to support the system epilepsy concept in this group of epilepsies, using them as models for epileptogenesis in general. The spectral continuity of the involved conditions is evidenced by several features: language impairment, the overarching presence of centrotemporal spikes and ripples (with changing electromorphology across the spectrum), the essential timely and spatial independence of interictal epileptic discharges from seizures, NREM sleep relatedness, and the existence of the intermediate-severity "atypical" forms. These epilepsies might be the consequences of a genetically determined transitory developmental failure, reflected by widespread neuropsychological symptoms originating from the perisylvian network that have distinct time and space relations from secondary epilepsy itself. The involved epilepsies carry the risk of progression to severe, potentially irreversible encephalopathic forms.
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Affiliation(s)
- Péter Halász
- Department of Neurology, University Medical School, Pécs, Hungary
| | - Anna Szũcs
- Institute of Behavioral Sciences, Semmelweis University, Budapest, Hungary
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Gaik M, Kojic M, Stegeman MR, Öncü‐Öner T, Kościelniak A, Jones A, Mohamed A, Chau PYS, Sharmin S, Chramiec‐Głąbik A, Indyka P, Rawski M, Biela A, Dobosz D, Millar A, Chau V, Ünalp A, Piper M, Bellingham MC, Eichler EE, Nickerson DA, Güleryüz H, Abbassi NEH, Jazgar K, Davis MJ, Mercimek‐Andrews S, Cingöz S, Wainwright BJ, Glatt S. Functional divergence of the two Elongator subcomplexes during neurodevelopment. EMBO Mol Med 2022; 14:e15608. [PMID: 35698786 PMCID: PMC9260213 DOI: 10.15252/emmm.202115608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 12/11/2022] Open
Abstract
The highly conserved Elongator complex is a translational regulator that plays a critical role in neurodevelopment, neurological diseases, and brain tumors. Numerous clinically relevant variants have been reported in the catalytic Elp123 subcomplex, while no missense mutations in the accessory subcomplex Elp456 have been described. Here, we identify ELP4 and ELP6 variants in patients with developmental delay, epilepsy, intellectual disability, and motor dysfunction. We determine the structures of human and murine Elp456 subcomplexes and locate the mutated residues. We show that patient-derived mutations in Elp456 affect the tRNA modification activity of Elongator in vitro as well as in human and murine cells. Modeling the pathogenic variants in mice recapitulates the clinical features of the patients and reveals neuropathology that differs from the one caused by previously characterized Elp123 mutations. Our study demonstrates a direct correlation between Elp4 and Elp6 mutations, reduced Elongator activity, and neurological defects. Foremost, our data indicate previously unrecognized differences of the Elp123 and Elp456 subcomplexes for individual tRNA species, in different cell types and in different key steps during the neurodevelopment of higher organisms.
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Russo A, Forest C, Leone GJ, Iascone M, Tenconi R, Maffei M, Cersosimo A, Cordelli DM, Suppiej A. ELP2 compound heterozygous variants associated with cortico-cerebellar atrophy, nodular heterotopia and epilepsy: Phenotype expansion and review of the literature. Eur J Med Genet 2021; 64:104361. [PMID: 34653680 DOI: 10.1016/j.ejmg.2021.104361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 08/02/2021] [Accepted: 10/08/2021] [Indexed: 10/20/2022]
Abstract
The elongator complex is a highly conserved macromolecular assembly composed by 6 individual proteins (Elp 1-6) and it is essential for many cellular functions such as transcription elongation, histone acetylation and tRNA modification. ELP2 is the second major subunit and with Elp1 and Elp3 it shapes the catalytic core of this essential complex. ELP2 gene pathogenic variants have been reported to be associated with several neurodevelopmental disorders, such as intellectual disability, severe motor development delay with truncal hypotonia, spastic diplegia, choreoathetosis, short stature and neuropsychiatric problems. Here we report a case with heterozygous variants of the ELP2 gene associated with unpublished electro-clinical and neuroimaging features, such as abnormal eye movements, focal epilepsy, cortico-cerebellar atrophy and nodular cortical heterotopia on brain MRI. A possible phenotype-genotype correlation and the electro-clinical and neuroimaging phenotype expansion of ELP2 mutations are here discussed, together with considerations on involved cortico-cerebellar networks and a detailed review of the literature.
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Affiliation(s)
- Angelo Russo
- IRCCS, Istituto delle Scienze Neurologiche di Bologna, UOC Neuropsichiatria dell'età pediatrica, Bologna, Italy
| | - Cristina Forest
- Department of Medical Sciences Pediatric Section, University of Ferrara, Italy.
| | - Giulia Joy Leone
- IRCCS, Istituto delle Scienze Neurologiche di Bologna, UOC Neuropsichiatria dell'età pediatrica, Bologna, Italy
| | - Maria Iascone
- Laboratorio di Genetica Medica, ASST Papa Giovanni XXIII, Bergamo, Italy
| | | | - Monica Maffei
- IRCCS, Istituto delle Scienze Neurologiche di Bologna, UOC Neuroradiologia, Bologna, Italy
| | - Antonella Cersosimo
- IRCCS, Istituto delle Scienze Neurologiche di Bologna, UOC Medicina Riabilitativa, Bologna, Italy
| | - Duccio Maria Cordelli
- IRCCS, Istituto delle Scienze Neurologiche di Bologna, UOC Neuropsichiatria dell'età pediatrica, Bologna, Italy
| | - Agnese Suppiej
- Department of Medical Sciences Pediatric Section, University of Ferrara, Italy; Robert Hollman Foundation, Padova, Italy
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