The Doublecortin and Doublecortin-Like Kinase 1 Genes Cooperate in Murine Hippocampal Development (original) (raw)
Related papers
Doublecortin Is Required in Mice for Lamination of the Hippocampus But Not the Neocortex
2002
Doublecortin (DCX) is a microtubule-associated protein that is required for normal neocortical and hippocampal development in humans. Mutations in the X-linked human DCX gene cause gross neocortical disorganization (lissencephaly or "smooth brain") in hemizygous males, whereas heterozygous females show a mosaic phenotype with a normal cortex as well as a second band of misplaced (heterotopic) neurons beneath the cortex ("double cortex syndrome"). We created a mouse carrying a targeted mutation in the Dcx gene. Hemizygous male Dcx mice show severe postnatal lethality; the few that survive to adulthood are variably fertile. Dcx mutant mice show neocorti-cal lamination that is largely indistinguishable from wild type and show normal patterns of neocortical neurogenesis and neuronal migration. In contrast, the hippocampus of both heterozygous females and hemizygous males shows disrupted lamination that is most severe in the CA3 region. Behavioral tests show defects in context and cued conditioned fear tests, suggesting that deficits in hippocampal learning accompany the abnormal cytoarchitecture.
Neuron, 2006
Although mutations in the human doublecortin gene (DCX) cause profound defects in cortical neuronal migration, a genetic deletion of Dcx in mice produces a milder defect. A second locus, doublecortin-like kinase (Dclk), encodes a protein with similar ''doublecortin domains'' and microtubule stabilization properties that may compensate for Dcx. Here, we generate a mouse with a Dclk mutation that causes no obvious migrational abnormalities but show that mice mutant for both Dcx and Dclk demonstrate perinatal lethality, disorganized neocortical layering, and profound hippocampal cytoarchitectural disorganization. Surprisingly, Dcx 2/y ;Dclk 2/2 mutants have widespread axonal defects, affecting the corpus callosum, anterior commissure, subcortical fiber tracts, and internal capsule. Dcx/Dclk-deficient dissociated neurons show abnormal axon outgrowth and dendritic structure, with defects in axonal transport of synaptic vesicle proteins. Dcx and Dclk may directly or indirectly regulate microtubule-based vesicle transport, a process critical to both neuronal migration and axon outgrowth.
The Journal of Comparative Neurology, 2008
During corticogenesis, radial glia-derived neural progenitors divide and migrate along radial fibers to their designated positions within the cortical plate. The microtubuleassociated proteins doublecortin (DCX) and doublecortin-like (DCL) are critically involved in neuronal migration and division, and may function in a partially redundant pathway. Since little is known about the important early stages of corticogenesis, when neurogenesis is extensive, we addressed a possible differential role by examining spatiotemporal expression patterns of DCX, DCL, and the radial glia marker vimentin during murine development. We found expression patterns of DCL and DCX to differ remarkably prior to embryonic day (E)13. DCL was already expressed at E9 and largely overlapped with vimentin, whereas DCX expression started modestly from E10/E11 onward. DCL was mainly found in the ventricular zone, often in mitotic cells and in pial-oriented radial fibers. In contrast, DCX was expressed in tangential fibers in the outer cortical regions. After E13, DCX and DCL expression largely overlapped but DCL expression had disappeared from the ventricular zone. Also, DCL levels were attenuated, whereas DCX remained high beyond E17. In conclusion, DCX and DCL are differentially expressed, particularly during early corticogenesis, consistent with their different functional roles. Given its involvement in mitosis, DCL appears to have a unique role in the early neuroepithelium that is different from later developmental stages when DCX is coexpressed.
The Journal of Comparative Neurology, 2012
We have characterized the expression of doublecortinlike (DCL), a microtubule-associated protein involved in embryonic neurogenesis that is highly homologous to doublecortin (DCX), in the adult mouse brain. To this end, we developed a DCL-specific antibody and used this to compare DCL expression with DCX. In the neurogenic regions of the adult brain like the subventricular zone (SVZ), the rostral migratory stream (RMS), the olfactory bulb (OB), and the hippocampus, DCL colocalizes with DCX in immature neuronal cell populations. In contrast to DCX, we also found high DCL expression in three other brain regions with suspected neurogenesis or neuronal plasticity. First, the radial glia-like, hypo
PLoS ONE, 2013
Heterotopic or aberrantly positioned cortical neurons are associated with epilepsy and intellectual disability. Various mouse models exist with forms of heterotopia, but the composition and state of cells developing in heterotopic bands has been little studied. Dcx knockout (KO) mice show hippocampal CA3 pyramidal cell lamination abnormalities, appearing from the age of E17.5, and mice suffer from spontaneous epilepsy. The Dcx KO CA3 region is organized in two distinct pyramidal cell layers, resembling a heterotopic situation, and exhibits hyperexcitability. Here, we characterized the abnormally organized cells in postnatal mouse brains. Electron microscopy confirmed that the Dcx KO CA3 layers at postnatal day (P) 0 are distinct and separated by an intermediate layer devoid of neuronal somata. We found that organization and cytoplasm content of pyramidal neurons in each layer were altered compared to wild type (WT) cells. Less regular nuclei and differences in mitochondria and Golgi apparatuses were identified. Each Dcx KO CA3 layer at P0 contained pyramidal neurons but also other closely apposed cells, displaying different morphologies. Quantitative PCR and immunodetections revealed increased numbers of oligodendrocyte precursor cells (OPCs) and interneurons in close proximity to Dcx KO pyramidal cells. Immunohistochemistry experiments also showed that caspase-3 dependent cell death was increased in the CA1 and CA3 regions of Dcx KO hippocampi at P2. Thus, unsuspected ultrastructural abnormalities and cellular heterogeneity may lead to abnormal neuronal function and survival in this model, which together may contribute to the development of hyperexcitability.
Multiple transcripts generated by the DCAMKL gene are expressed in the rat hippocampus
Molecular Brain Research, 2001
We have recently cloned a novel Doublecortin CaMK-like kinase (rDCAMKL) cDNA, and a related cDNA called CaMK-related peptide (CARP) from the rat hippocampus. These genes are structurally highly similar to the human DCAMKL-1 gene and doublecortin, a gene associated with X-linked lissencephaly and subcortical band heterotopia. Here we report on the genomic organization of the murine DCAMKL gene and its products. Our results show that DCAMKL and CARP are alternative splice products of the same gene. The DCAMKL gene also generates three alternatively-spliced rDCAMKL transcripts of which we have cloned the corresponding cDNAs and which potentially generate different DCAMKL proteins. In situ hybridization experiments show that the different rDCAMKL transcripts are all expressed in the adult rat hippocampus. We conclude that alternative splicing of the DCAMKL gene may generate different but similar proteins in the adult rat hippocampus thereby regulating different but overlapping aspects of DCAMKL controlled neuronal plasticity.
Neuron, 2006
The mechanisms controlling neurogenesis during brain development remain relatively unknown. Through a differential protein screen with developmental versus mature neural tissues, we identified a group of developmentally enriched microtubule-associated proteins (MAPs) including doublecortin-like kinase (DCLK), a protein that shares high homology with doublecortin (DCX). DCLK, but not DCX, is highly expressed in regions of active neurogenesis in the neocortex and cerebellum. Through a dynein-dependent mechanism, DCLK regulates the formation of bipolar mitotic spindles and the proper transition from prometaphase to metaphase during mitosis. In cultured cortical neural progenitors, DCLK RNAi Lentivirus disrupts the structure of mitotic spindles and the progression of M phase, causing an increase of cell-cycle exit index and an ectopic commitment to a neuronal fate. Furthermore, both DCLK gain and loss of function in vivo specifically promote a neuronal identity in neural progenitors. Th...
Neuron, 1999
in the deeper layers, while later born neurons cross through these layers to successively reach regions closer to the cerebral surface (reviewed by Caviness et al., 1997). In this way, a six-layered neocortex develops. Migrating neurons mainly travel in association with radially extending glial fibres (Rakic, Yoheved Berwald-Netter, † Philippe Denoulet, † 1971; Luskin et al., 1988); however, tangential and chain and Jamel Chelly* migration have also been observed in some brain re-* U129 de l'INSERM gions (Luskin, 1993; Tan and Breen, 1993; O'Rourke et Institut Cochin de Gé né tique Molé culaire al., 1995; Lois et al., 1996). Many questions still remain 24, rue du Faubourg Saint Jacques concerning the corticogenesis process: the signals that 75014 Paris determine the timing of cells leaving the proliferative † Laboratoire de Biochimie Cellulaire pool, which ultimately affects their laminar fate (Frantz CNRS UPR 9065 and McConnell, 1996), the mechanism and direction of Collè ge de France cell locomotion, and the recognition of the final desti-11, Place M. Berthelot nation. 75005 Paris Lissencephaly is a cortical malformation disorder as-France sociated with severe mental retardation and epilepsy ‡ Department of Biological Sciences (Harding, 1996), which exists as an X-linked disease (X-LIS) Stanford University caused by mutations in the doublecortin gene (des Stanford, California 94305 Portes et al., 1998a; Gleeson et al., 1998). Another re- § Department of Molecular Genetics lated disorder is Miller Dieker syndrome consisting of The Weizmann Institute of Science lissencephaly with characteristic facial abnormalities 76100 Rehovot (Dobyns et al., 1991), which is associated with the loss Israel of function of the LIS1 gene product (Reiner et al., 1993; Hattori et al., 1994). Patients with lissencephaly have a thickened disorganized cortex, lacking the characteris-Summary tic laminar pattern, and the surface of the brain is smooth without the gyri or folds found in normal individuals. Recently, we and others reported that the doublecortin X-LIS is often associated within the same pedigree with gene is responsible for X-linked lissencephaly and a second cortical dysgenesis disorder, subcortical lamisubcortical laminar heterotopia. Here, we show that nar heterotopia (SCLH, Pinard et al., 1994), which mainly Doublecortin is expressed in the brain throughout the affects females, and is characterized by an apparently period of corticogenesis in migrating and differentiattrue cortex, but with a heterotopic layer of misplaced ing neurons. Immunohistochemical studies show its neurons. Mutations in the doublecortin gene account localization in the soma and leading processes of tanfor most cases of SCLH (des Portes et al., 1998b). Both gentially migrating neurons, and a strong axonal label-X-LIS and SCLH are believed to be disorders of neuronal ing is observed in differentiating neurons. In cultured migration; however, the function of Doublecortin and neurons, Doublecortin expression is highest in the disthe pathophysiological mechanisms that result from its tal parts of developing processes. We demonstrate by deficit remain unknown. sedimentation and microscopy studies that Double-Several other genes have been isolated that, when cortin is associated with microtubules (MTs) and posdisrupted, cause neuronal migration disorders in mice. tulate that it is a novel MAP. Our data suggest that One of them encodes Reelin, an extracellular matrix the cortical dysgeneses associated with the loss of protein expressed by the Cajal-Retzius cells of the mar-Doublecortin function might result from abnormal cyginal zone (D'Arcangelo et al., 1995; Hirotsune et al., toskeletal dynamics in neuronal cell development. 1995), which is mutated in the reeler mouse. Since Reelin is a secreted protein, its mode of action may be as a guidance molecule or stop signal for migrating neurons T. (1997). Scrambler and yotari disrupt the disabled gene and produce a reeler-like phenotype in mice. Nature 389, 730-733. Tan, S.-S., and Breen, S.J. (1993). Radial mosaicism and tangential cell dispersion both contribute to mouse neocortical development. Nature 362, 638-640. Tanaka, E., and Sabry, J. (1995). Making the connection: cytoskeletal rearrangements during growth cone guidance. Cell 83, 171-176. Tucker, R.P. (1990). The roles of microtubule-associated proteins
European Journal of Neuroscience, 2007
During corticogenesis, progenitors divide within the ventricular zone where they rely on radial process extensions, formed by radial glial cell (RG) scaffolds, along which they migrate to the proper layers of the cerebral cortex. Although the microtubule-associated proteins doublecortin (DCX) and doublecortin-like kinase (DCLK) are critically involved in dynamic rearrangement of the cytoskeletal machinery that allow migration, little is known about their role in early corticogenesis. Here we have functionally characterized a mouse splice-variant of DCLK, doublecortin-like (DCL), exhibiting 73% amino acid sequence identity with DCX over its entire length. Unlike DCX, DCL is expressed from embryonic day 8 onwards throughout the early neuroepithelium. It is localized in mitotic cells, RGs and radial processes. DCL knockdown using siRNA in vitro induces spindle collapse in dividing neuroblastoma cells, whereas overexpression results in elongated and asymmetrical mitotic spindles. In vivo knockdown of the DCLK gene by in utero electroporation significantly reduced cell numbers in the inner proliferative zones and dramatically disrupted most radial processes. Our data emphasize the unique role of the DCLK gene in mitotic spindle integrity during early neurogenesis. In addition, they indicate crucial involvement of DCLK in RG proliferation and their radial process stability, a finding that has thus far not been attributed to DCX or DCLK.