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Wang G, Lei J, Wang Y, Yu J, He Y, Zhao W, Hu Z, Xu Z, Jin Y, Gu Y, Guo X, Yang B, Gao Z, Wang Z. The ZSWIM8 ubiquitin ligase regulates neurodevelopment by guarding the protein quality of intrinsically disordered Dab1. Cereb Cortex 2022; 33:3866-3881. [PMID: 35989311 DOI: 10.1093/cercor/bhac313] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 11/15/2022] Open
Abstract
Protein quality control (PQC) is essential for maintaining protein homeostasis and guarding the accuracy of neurodevelopment. Previously, we found that a conserved EBAX-type CRL regulates the protein quality of SAX-3/ROBO guidance receptors in Caenorhabditis elegans. Here, we report that ZSWIM8, the mammalian homolog of EBAX-1, is essential for developmental stability of mammalian brains. Conditional deletion of Zswim8 in the embryonic nervous system causes global cellular stress, partial perinatal lethality and defective migration of neural progenitor cells. CRISPR-mediated knockout of ZSWIM8 impairs spine formation and synaptogenesis in hippocampal neurons. Mechanistic studies reveal that ZSWIM8 controls protein quality of Disabled 1 (Dab1), a key signal molecule for brain development, thus protecting the signaling strength of Dab1. As a ubiquitin ligase enriched with intrinsically disordered regions (IDRs), ZSWIM8 specifically recognizes IDRs of Dab1 through a "disorder targets misorder" mechanism and eliminates misfolded Dab1 that cannot be properly phosphorylated. Adult survivors of ZSWIM8 CKO show permanent hippocampal abnormality and display severely impaired learning and memory behaviors. Altogether, our results demonstrate that ZSWIM8-mediated PQC is critical for the stability of mammalian brain development.
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Affiliation(s)
- Guan Wang
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Jing Lei
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Yifeng Wang
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Jiahui Yu
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
- Chu Kochen Honors College of Zhejiang University, Hangzhou 310058, China
| | - Yinghui He
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Weiqi Zhao
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Zhechun Hu
- Center of Stem Cell and Regenerative Medicine, and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Zhenzhong Xu
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yan Gu
- Center of Stem Cell and Regenerative Medicine, and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Xing Guo
- The Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Bing Yang
- The Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Zhihua Gao
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Zhiping Wang
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China; The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
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2
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Terry BK, Park R, Cho SH, Crino PB, Kim S. Abnormal activation of Yap/Taz contributes to the pathogenesis of tuberous sclerosis complex. Hum Mol Genet 2022; 31:1979-1996. [PMID: 34999833 PMCID: PMC9239747 DOI: 10.1093/hmg/ddab374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/31/2021] [Accepted: 12/27/2021] [Indexed: 01/09/2023] Open
Abstract
The multi-systemic genetic disorder tuberous sclerosis complex (TSC) impacts multiple neurodevelopmental processes including neuronal morphogenesis, neuronal migration, myelination and gliogenesis. These alterations contribute to the development of cerebral cortex abnormalities and malformations. Although TSC is caused by mTORC1 hyperactivation, cognitive and behavioral impairments are not improved through mTORC1 targeting, making the study of the downstream effectors of this complex important for understanding the mechanisms underlying TSC. As mTORC1 has been shown to promote the activity of the transcriptional co-activator Yap, we hypothesized that altered Yap/Taz signaling contributes to the pathogenesis of TSC. We first observed that the levels of Yap/Taz are increased in human cortical tuber samples and in embryonic cortices of Tsc2 conditional knockout (cKO) mice. Next, to determine how abnormal upregulation of Yap/Taz impacts the neuropathology of TSC, we deleted Yap/Taz in Tsc2 cKO mice. Importantly, Yap/Taz/Tsc2 triple conditional knockout (tcKO) animals show reduced cortical thickness and cortical neuron cell size, despite the persistence of high mTORC1 activity, suggesting that Yap/Taz play a downstream role in cytomegaly. Furthermore, Yap/Taz/Tsc2 tcKO significantly restored cortical and hippocampal lamination defects and reduced hippocampal heterotopia formation. Finally, the loss of Yap/Taz increased the distribution of myelin basic protein in Tsc2 cKO animals, consistent with an improvement in myelination. Overall, our results indicate that targeting Yap/Taz lessens the severity of neuropathology in a TSC animal model. This study is the first to implicate Yap/Taz as contributors to cortical pathogenesis in TSC and therefore as potential novel targets in the treatment of this disorder.
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Affiliation(s)
- Bethany K Terry
- Department of Neural Sciences, Lewis Katz School of Medicine, Shriners Hospitals Pediatrics Research Center, Temple University, Philadelphia, PA 19140, USA,Biomedical Sciences Graduate Program, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Raehee Park
- Department of Neural Sciences, Lewis Katz School of Medicine, Shriners Hospitals Pediatrics Research Center, Temple University, Philadelphia, PA 19140, USA
| | - Seo-Hee Cho
- Department of Medicine, Sidney Kimmel Medical College, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Peter B Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Seonhee Kim
- To whom correspondence should be addressed. Tel: 215-926-9360; Fax: 215-926-9325;
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3
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Camblor-Perujo S, Kononenko NL. Brain-specific functions of the endocytic machinery. FEBS J 2021; 289:2219-2246. [PMID: 33896112 DOI: 10.1111/febs.15897] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/29/2021] [Indexed: 12/12/2022]
Abstract
Endocytosis is an essential cellular process required for multiple physiological functions, including communication with the extracellular environment, nutrient uptake, and signaling by the cell surface receptors. In a broad sense, endocytosis is accomplished through either constitutive or ligand-induced invagination of the plasma membrane, which results in the formation of the plasma membrane-retrieved endocytic vesicles, which can either be sent for degradation to the lysosomes or recycled back to the PM. This additional function of endocytosis in membrane retrieval has been adopted by excitable cells, such as neurons, for membrane equilibrium maintenance at synapses. The last two decades were especially productive with respect to the identification of brain-specific functions of the endocytic machinery, which additionally include but not limited to regulation of neuronal differentiation and migration, maintenance of neuron morphology and synaptic plasticity, and prevention of neurotoxic aggregates spreading. In this review, we highlight the current knowledge of brain-specific functions of endocytic machinery with a specific focus on three brain cell types, neuronal progenitor cells, neurons, and glial cells.
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Affiliation(s)
| | - Natalia L Kononenko
- CECAD Cluster of Excellence, University of Cologne, Germany.,Center for Physiology & Pathophysiology, Medical Faculty, University of Cologne, Germany
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4
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Defective Reelin/Dab1 signaling pathways associated with disturbed hippocampus development of homozygous yotari mice. Mol Cell Neurosci 2021; 112:103614. [PMID: 33845123 DOI: 10.1016/j.mcn.2021.103614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/17/2021] [Accepted: 04/03/2021] [Indexed: 12/17/2022] Open
Abstract
Homozygous Dab1 yotari mutant mice, Dab1yot (yot/yot) mice, have an autosomal recessive mutation of Dab1 and show reeler-like phenotype including histological abnormality of the cerebellum, hippocampus, and cerebral cortex. We here show abnormal hippocampal development of yot/yot mice where granule cells and pyramidal cells fail to form orderly rows but are dispersed diffusely in vague multiplicative layers. Possibly due to the positioning failure of granule cells and pyramidal cells and insufficient synaptogenesis, axons of the granule cells did not extend purposefully to connect with neighboring regions in yot/yot mice. We found that both hippocampal granule cells and pyramidal cells of yot/yot mice expressed proteins reactive with the anti-Dab1 antibody. We found that Y198- phosphorylated Dab1 of yot/yot mice was greatly decreased. Accordingly the downstream molecule, Akt was hardly phosphorylated. Especially, synapse formation was defective and the distribution of neurons was scattered in hippocampus of yot/yot mice. Some of neural cell adhesion molecules and hippocampus associated transcription factors of the neurons were expressed aberrantly, suggesting that the Reelin-Dab1 signaling pathway seemed to be importantly involved in not only neural migration as having been shown previously but also neural maturation and/or synaptogenesis of the mice. It is interesting to clarify whether the defective neural maturation is a direct consequence of the dysfunctional Dab1, or alternatively secondarily due to the Reelin-Dab1 intracellular signaling pathways.
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5
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Lawrenson ID, Krebs DL, Linossi EM, Zhang JG, McLennan TJ, Collin C, McRae HM, Kolesnik TB, Koh K, Britto JM, Kueh AJ, Sheikh BN, El-Saafin F, Nicola NA, Tan SS, Babon JJ, Nicholson SE, Alexander WS, Thomas T, Voss AK. Cortical Layer Inversion and Deregulation of Reelin Signaling in the Absence of SOCS6 and SOCS7. Cereb Cortex 2018; 27:576-588. [PMID: 26503265 DOI: 10.1093/cercor/bhv253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mutations of the reelin gene cause severe defects in cerebral cortex development and profound intellectual impairment. While many aspects of the reelin signaling pathway have been identified, the molecular and ultimate cellular consequences of reelin signaling remain unknown. Specifically, it is unclear if termination of reelin signaling is as important for normal cortical neuron migration as activation of reelin signaling. Using mice that are single or double deficient, we discovered that combined loss of the suppressors of cytokine signaling, SOCS6 and SOCS7, recapitulated the cortical layer inversion seen in mice lacking reelin and led to a dramatic increase in the reelin signaling molecule disabled (DAB1) in the cortex. The SRC homology domains of SOCS6 and SOCS7 bound DAB1 ex vivo. Mutation of DAB1 greatly diminished binding and protected from degradation by SOCS6. Phosphorylated DAB1 was elevated in cortical neurons in the absence of SOCS6 and SOCS7. Thus, constitutive activation of reelin signaling was observed to be equally detrimental as lack of activation. We hypothesize that, by terminating reelin signaling, SOCS6 and SOCS7 may allow new cycles of reelin signaling to occur and that these may be essential for cortical neuron migration.
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Affiliation(s)
- Isobel D Lawrenson
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia
| | - Danielle L Krebs
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Current address: Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Edmond M Linossi
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Jian-Guo Zhang
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Tamara J McLennan
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia
| | - Caitlin Collin
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia
| | - Helen M McRae
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Tatiana B Kolesnik
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia
| | - Katrina Koh
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Joanne M Britto
- Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3010, Australia
| | - Andrew J Kueh
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Bilal N Sheikh
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Farrah El-Saafin
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Nicos A Nicola
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Seong-Seng Tan
- Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3010, Australia
| | - Jeffrey J Babon
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Sandra E Nicholson
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Warren S Alexander
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Tim Thomas
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Anne K Voss
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
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6
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Bock HH, May P. Canonical and Non-canonical Reelin Signaling. Front Cell Neurosci 2016; 10:166. [PMID: 27445693 PMCID: PMC4928174 DOI: 10.3389/fncel.2016.00166] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/08/2016] [Indexed: 12/11/2022] Open
Abstract
Reelin is a large secreted glycoprotein that is essential for correct neuronal positioning during neurodevelopment and is important for synaptic plasticity in the mature brain. Moreover, Reelin is expressed in many extraneuronal tissues; yet the roles of peripheral Reelin are largely unknown. In the brain, many of Reelin's functions are mediated by a molecular signaling cascade that involves two lipoprotein receptors, apolipoprotein E receptor-2 (Apoer2) and very low density-lipoprotein receptor (Vldlr), the neuronal phosphoprotein Disabled-1 (Dab1), and members of the Src family of protein tyrosine kinases as crucial elements. This core signaling pathway in turn modulates the activity of adaptor proteins and downstream protein kinase cascades, many of which target the neuronal cytoskeleton. However, additional Reelin-binding receptors have been postulated or described, either as coreceptors that are essential for the activation of the "canonical" Reelin signaling cascade involving Apoer2/Vldlr and Dab1, or as receptors that activate alternative or additional signaling pathways. Here we will give an overview of canonical and alternative Reelin signaling pathways, molecular mechanisms involved, and their potential physiological roles in the context of different biological settings.
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Affiliation(s)
- Hans H Bock
- Clinic of Gastroenterology and Hepatology, Heinrich-Heine-University Düsseldorf Düsseldorf, Germany
| | - Petra May
- Clinic of Gastroenterology and Hepatology, Heinrich-Heine-University Düsseldorf Düsseldorf, Germany
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7
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Korn MJ, Mandle QJ, Parent JM. Conditional Disabled-1 Deletion in Mice Alters Hippocampal Neurogenesis and Reduces Seizure Threshold. Front Neurosci 2016; 10:63. [PMID: 26941603 PMCID: PMC4766299 DOI: 10.3389/fnins.2016.00063] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/10/2016] [Indexed: 11/13/2022] Open
Abstract
Many animal models of temporal lobe epilepsy (TLE) exhibit altered neurogenesis arising from progenitors within the dentate gyrus subgranular zone (SGZ). Aberrant integration of new neurons into the existing circuit is thought to contribute to epileptogenesis. In particular, adult-born neurons that exhibit ectopic migration and hilar basal dendrites (HBDs) are suggested to be pro-epileptogenic. Loss of reelin signaling may contribute to these morphological changes in patients with epilepsy. We previously demonstrated that conditional deletion of the reelin adaptor protein, disabled-1 (Dab1), from postnatal mouse SGZ progenitors generated dentate granule cells (DGCs) with abnormal dendritic development and ectopic placement. To determine whether the early postnatal loss of reelin signaling is epileptogenic, we conditionally deleted Dab1 in neural progenitors and their progeny on postnatal days 7–8 and performed chronic video-EEG recordings 8–10 weeks later. Dab1-deficient mice did not have spontaneous seizures but exhibited interictal epileptiform abnormalities and a significantly reduced latency to pilocarpine-induced status epilepticus. After chemoconvulsant treatment, over 90% of mice deficient for Dab1 developed generalized motor convulsions with tonic-clonic movements, rearing, and falling compared to <20% of wild-type mice. Recombination efficiency, measured by Cre reporter expression, inversely correlated with time to the first sustained seizure. These pro-epileptogenic changes were associated with decreased neurogenesis and increased numbers of hilar ectopic DGCs. Interestingly, neurons co-expressing the Cre reporter comprised a fraction of these hilar ectopic DGCs cells, suggesting a non-cell autonomous effect for the loss of reelin signaling. We also noted a dispersion of the CA1 pyramidal layer, likely due to hypomorphic effects of the conditional Dab1 allele, but this abnormality did not correlate with seizure susceptibility. These findings suggest that the misplacement or reduction of postnatally-generated DGCs contributes to aberrant circuit development and hyperexcitability, but aberrant neurogenesis after conditional Dab1 deletion alone is not sufficient to produce spontaneous seizures.
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Affiliation(s)
- Matthew J Korn
- Department of Neurology, University of Michigan Medical Center Ann Arbor, MI, USA
| | - Quinton J Mandle
- Department of Neurology, University of Michigan Medical Center Ann Arbor, MI, USA
| | - Jack M Parent
- Department of Neurology, University of Michigan Medical CenterAnn Arbor, MI, USA; VA Ann Arbor Healthcare SystemAnn Arbor, MI, USA
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8
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Moon UY, Park JY, Park R, Cho JY, Hughes LJ, McKenna J, Goetzl L, Cho SH, Crino PB, Gambello MJ, Kim S. Impaired Reelin-Dab1 Signaling Contributes to Neuronal Migration Deficits of Tuberous Sclerosis Complex. Cell Rep 2015; 12:965-78. [PMID: 26235615 PMCID: PMC4536164 DOI: 10.1016/j.celrep.2015.07.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 06/01/2015] [Accepted: 07/07/2015] [Indexed: 01/06/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is associated with neurodevelopmental abnormalities, including defects in neuronal migration. However, the alterations in cell signaling mechanisms critical for migration and final positioning of neurons in TSC remain unclear. Our detailed cellular analyses reveal that reduced Tsc2 in newborn neurons causes abnormalities in leading processes of migrating neurons, accompanied by significantly delayed migration. Importantly, we demonstrate that Reelin-Dab1 signaling is aberrantly regulated in TSC mouse models and in cortical tubers from TSC patients owing to enhanced expression of the E3 ubiquitin ligase Cul5, a known mediator of pDab1 ubiquitination. Likewise, mTORC1 activation by Rheb overexpression generates similar neuronal and Reelin-Dab1 signaling defects, and directly upregulates Cul5 expression. Inhibition of mTORC1 by rapamycin treatment or by reducing Cul5 largely restores normal leading processes and positioning of migrating neurons. Thus, disrupted Reelin-Dab1 signaling is critically involved in the neuronal migration defects of TSC.
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Affiliation(s)
- Uk Yeol Moon
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jun Young Park
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Raehee Park
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jennifer Y Cho
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Lucinda J Hughes
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Graduate Program of Biomedical Sciences, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - James McKenna
- Department of Human Genetics, Emory University, School of Medicine, Atlanta, GA 30322, USA
| | - Laura Goetzl
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Obstetrics Gynecology and Reproductive Sciences, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Seo-Hee Cho
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Peter B Crino
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Neurology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Michael J Gambello
- Department of Human Genetics, Emory University, School of Medicine, Atlanta, GA 30322, USA
| | - Seonhee Kim
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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9
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Yap CC, Winckler B. Adapting for endocytosis: roles for endocytic sorting adaptors in directing neural development. Front Cell Neurosci 2015; 9:119. [PMID: 25904845 PMCID: PMC4389405 DOI: 10.3389/fncel.2015.00119] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 03/16/2015] [Indexed: 01/01/2023] Open
Abstract
Proper cortical development depends on the orchestrated actions of a multitude of guidance receptors and adhesion molecules and their downstream signaling. The levels of these receptors on the surface and their precise locations can greatly affect guidance outcomes. Trafficking of receptors to a particular surface locale and removal by endocytosis thus feed crucially into the final guidance outcomes. In addition, endocytosis of receptors can affect downstream signaling (both quantitatively and qualitatively) and regulated endocytosis of guidance receptors is thus an important component of ensuring proper neural development. We will discuss the cell biology of regulated endocytosis and the impact on neural development. We focus our discussion on endocytic accessory proteins (EAPs) (such as numb and disabled) and how they regulate endocytosis and subsequent post-endocytic trafficking of their cognate receptors (such as Notch, TrkB, β-APP, VLDLR, and ApoER2).
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Affiliation(s)
- Chan Choo Yap
- Department of Neuroscience, University of Virginia Charlottesville, VA, USA
| | - Bettina Winckler
- Department of Neuroscience, University of Virginia Charlottesville, VA, USA
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10
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Gaillard F, Kuny S, Sauvé Y. Retinal distribution of Disabled-1 in a diurnal murine rodent, the Nile grass rat Arvicanthis niloticus. Exp Eye Res 2014; 125:236-43. [PMID: 24992207 DOI: 10.1016/j.exer.2014.06.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/18/2014] [Accepted: 06/19/2014] [Indexed: 11/29/2022]
Abstract
We sought to study the expression pattern of Disabled-1 (Dab1; an adaptor protein in the reelin pathway) in the cone-rich retina of a diurnal murine rodent. Expression was examined by western blotting and immunohistochemistry using well-established antibodies against Dab1 and various markers of retinal neurons. Western blots revealed the presence of Dab1 (80 kDa) in brain and retina of the Nile grass rat. Retinal immunoreactivity was predominant in soma and dendrites of horizontal cells as well as in amacrine cell bodies aligned at the INL/IPL border. Dab1(+) neurons in the inner retina do not stain for parvalbumin, calbindin, protein kinase C-alpha, choline acetyltransferase, glutamic acid decarboxylase, or tyrosine hydroxylase. They express, however, the glycine transporter GlyT1. They have small ovoid cell bodies (7.1 ± 1.06 μm in diameter) and bistratified terminal plexii in laminas a and b of the IPL. Dab1(+) amacrine cells are evenly distributed across the retina (2600 cells/mm(2)) in a fairly regular mosaic (regularity indexes ≈3.3-5.5). We conclude that retinal Dab1 in the adult Nile grass rat exhibits a dual cell patterning similar to that found in human. It is expressed in horizontal cells as well as in a subpopulation of glycinergic amacrine cells undetectable with antibodies against calcium-binding proteins. These amacrine cells are likely of the AII type.
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Affiliation(s)
- Frédéric Gaillard
- Department of Ophthalmology and Visual Science, University of Alberta, Edmonton, AB, Canada
| | - Sharee Kuny
- Department of Ophthalmology and Visual Science, University of Alberta, Edmonton, AB, Canada
| | - Yves Sauvé
- Department of Ophthalmology and Visual Science, University of Alberta, Edmonton, AB, Canada; Department of Physiology, University of Alberta, Edmonton, AB, Canada.
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11
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Franco SJ, Martinez-Garay I, Gil-Sanz C, Harkins-Perry SR, Müller U. Reelin regulates cadherin function via Dab1/Rap1 to control neuronal migration and lamination in the neocortex. Neuron 2011; 69:482-97. [PMID: 21315259 DOI: 10.1016/j.neuron.2011.01.003] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2011] [Indexed: 10/18/2022]
Abstract
Neuronal migration is critical for establishing neocortical cell layers and migration defects can cause neurological and psychiatric diseases. Recent studies show that radially migrating neocortical neurons use glia-dependent and glia-independent modes of migration, but the signaling pathways that control different migration modes and the transitions between them are poorly defined. Here, we show that Dab1, an essential component of the reelin pathway, is required in radially migrating neurons for glia-independent somal translocation, but not for glia-guided locomotion. During migration, Dab1 acts in translocating neurons to stabilize their leading processes in a Rap1-dependent manner. Rap1, in turn, controls cadherin function to regulate somal translocation. Furthermore, cell-autonomous neuronal deficits in somal translocation are sufficient to cause severe neocortical lamination defects. Thus, we define the cellular mechanism of reelin function during radial migration, elucidate the molecular pathway downstream of Dab1 during somal translocation, and establish the importance of glia-independent motility in neocortical development.
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Affiliation(s)
- Santos J Franco
- Dorris Neuroscience Center and Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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12
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Zhao S, Frotscher M. Go or stop? Divergent roles of Reelin in radial neuronal migration. Neuroscientist 2011; 16:421-34. [PMID: 20817919 DOI: 10.1177/1073858410367521] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuronal migration is an essential step of brain development and is controlled by a variety of cellular proteins and extracellular matrix molecules. Reelin, an extracellular matrix protein, is required for neuronal migration. Over the past 10 years, the Reelin signaling cascade has been studied intensively. However, the role of Reelin in neuronal migration has remained unclear. Different Reelin fragments and different Reelin receptors suggest multiple functions of Reelin. In this review, the authors focus on Reelin effects on the actin cytoskeleton of migrating neurons.
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Affiliation(s)
- Shanting Zhao
- Institute of Anatomy and Cell Biology, University of Freiburg, Freiburg, Germany
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13
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Serine phosphorylation regulates disabled-1 early isoform turnover independently of Reelin. Cell Signal 2010; 23:555-65. [PMID: 21111810 DOI: 10.1016/j.cellsig.2010.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 11/17/2010] [Indexed: 12/27/2022]
Abstract
The Reelin-Disabled 1 (Dab1) signaling pathway plays an important role in neuronal cell migration during brain development. Dab1, an intracellular adapter protein which is tyrosine phosphorylated upon Reelin stimulation, has been directly implicated in the transmission and termination of Reelin-mediated signaling. Two main forms of Dab1 have been identified in the developing chick retina, an early isoform (Dab1-E) expressed in progenitor cells and a late isoform (Dab1-L, a.k.a. Dab1) expressed in differentiated cells. Dab1-E is missing two Src family kinase (SFK) phosphorylation sites that are critical for Reelin-Dab1 signaling and is not tyrosine phosphorylated. We have recently demonstrated a role for Dab1-E in the maintenance of retinal progenitor cells. Here, we report that Dab1-E is phosphorylated at serine/threonine residues independent of Reelin. Cdk2, highly expressed in retinal progenitor cells, mediates Dab1-E phosphorylation at serine 475 which in turn promotes ubiquitination-triggered proteasome degradation of Dab1-E. Inhibition of protein phosphatase 1 and/or protein phosphatase 2A leads to increased Dab1-E instability. We propose that Dab1 turnover is regulated by both Reelin-independent serine/threonine phosphorylation and Reelin-dependent tyrosine phosphorylation.
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14
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The early isoform of disabled-1 functions independently of Reelin-mediated tyrosine phosphorylation in chick retina. Mol Cell Biol 2010; 30:4339-53. [PMID: 20606009 DOI: 10.1128/mcb.00545-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The Reelin-Disabled-1 (Dab1) signaling pathway plays a key role in the positioning of neurons during brain development. Two alternatively spliced Dab1 isoforms have been identified in chick retina and brain: Dab1-E, expressed at early stages of development, and Dab1-L (commonly referred to as Dab1), expressed at later developmental stages. The well-studied Dab1-L serves as an adaptor protein linking Reelin signal to its downstream effectors; however, nothing is known regarding the role of Dab1-E. Here we show that Dab1-E is primarily expressed in proliferating retinal progenitor cells whereas Dab1-L is found exclusively in differentiated neuronal cells. In contrast to Dab1-L, which is tyrosine phosphorylated upon Reelin stimulation, Dab1-E is not tyrosine phosphorylated and may function independently of Reelin. Knockdown of Dab1-E in chick retina results in a significant reduction in the number of proliferating cells and promotes ganglion cell differentiation. Our results demonstrate a role for Dab1-E in the maintenance of the retinal progenitor pool and determination of cell fate.
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15
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Characterisation and differential expression during development of a duplicate Disabled-1 (Dab1) gene from zebrafish. Comp Biochem Physiol B Biochem Mol Biol 2010; 155:217-29. [DOI: 10.1016/j.cbpb.2009.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 11/04/2009] [Accepted: 11/08/2009] [Indexed: 11/22/2022]
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16
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Abstract
Reelin coordinates the movements of neurons during brain development by signaling through the Dab1 adaptor and Src family tyrosine kinases. Experiments with cultured neurons have shown that when Dab1 is phosphorylated on tyrosine, it activates Akt and provides a scaffold for assembling signaling complexes, including the paralogous Crk and CrkL adaptors. The roles of Akt and Dab1 complexes during development have been unclear. We have generated two Dab1 alleles, each lacking two out of the four putative tyrosine phosphorylation sites. Neither allele supports normal brain development, but each allele complements the other. Two tyrosines are required for Reelin to stimulate Dab1 phosphorylation at the other sites, to activate Akt, and to downregulate Dab1 levels. The other two tyrosines are required to stimulate a Crk/CrkL-C3G pathway. The absence of Crk/CrkL binding sites and C3G activation causes an unusual layering phenotype. These results show that Reelin-induced Akt stimulation and Dab1 turnover are not sufficient for normal development and suggest that Dab1 acts both as a kinase switch and as a scaffold for assembling signaling complexes in vivo.
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17
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Díaz-Ruiz C, Parlato R, Aguado F, Ureña JM, Burgaya F, Martínez A, Carmona MA, Kreiner G, Bleckmann S, Del Río JA, Schütz G, Soriano E. Regulation of neural migration by the CREB/CREM transcription factors and altered Dab1 levels in CREB/CREM mutants. Mol Cell Neurosci 2008; 39:519-28. [PMID: 18786638 DOI: 10.1016/j.mcn.2008.07.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 07/11/2008] [Accepted: 07/14/2008] [Indexed: 01/27/2023] Open
Abstract
The family of CREB transcription factors is involved in a variety of biological processes including the development and plasticity of the nervous system. To gain further insight into the roles of CREB family members in the development of the embryonic brain, we examined the migratory phenotype of CREB1(Nescre)CREM(-/-) mutants. We found that the lack of CREB/CREM genes is accompanied by anatomical defects in specific layers of the olfactory bulb, hippocampus and cerebral cortex. These changes are associated with decreased Dab1 expression in CREB1(Nescre)CREM(-/-) mutants. Our results indicate that the lack of CREB/CREM genes, specifically in neural and glial progenitors, leads to migration abnormalities during brain development, suggesting that unidentified age-dependent factors modulate the role of CREB/CREM genes in neural development.
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Affiliation(s)
- Carmen Díaz-Ruiz
- Institute for Research in Biomedicine-Barcelona (IRB), Department of Cell Biology and CIBERNED (ISCIII), University of Barcelona, Barcelona Science Park, Lab A1-S1, Josep Samitier 1-5, Barcelona 08028, Spain
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18
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A high through-put reverse genetic screen identifies two genes involved in remote memory in mice. PLoS One 2008; 3:e2121. [PMID: 18464936 PMCID: PMC2373872 DOI: 10.1371/journal.pone.0002121] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Accepted: 03/10/2008] [Indexed: 11/25/2022] Open
Abstract
Previous studies have revealed that the initial stages of memory formation require several genes involved in synaptic, transcriptional and translational mechanisms. In contrast, very little is known about the molecular and cellular mechanisms underlying later stages of memory, including remote memory (i.e. 7-day memory). To identify genes required for remote memory, we screened randomly selected mouse strains harboring known mutations. In our primary reverse genetic screen, we identified 4 putative remote memory mutant strains out of a total of 54 lines analyzed. Additionally, we found 11 other mutant strains with other abnormal profiles. Secondary screens confirmed that mutations of integrin β2 (Itgβ2) and steryl-O-acyl transferase 1 (Soat1) specifically disrupted remote memory. This study identifies some of the first genes required for remote memory, and suggests that screens of targeted mutants may be an efficient strategy to identify molecular requirements for this process.
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19
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Cooper JA. A mechanism for inside-out lamination in the neocortex. Trends Neurosci 2008; 31:113-9. [PMID: 18255163 DOI: 10.1016/j.tins.2007.12.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 12/03/2007] [Accepted: 12/04/2007] [Indexed: 01/16/2023]
Abstract
We outline a unified model for inside-out layering of the neocortex, hinging on a new interpretation for the effects of Reelin on neuronal migrations. The effects of Reelin on cortical structure have been analyzed in great detail, but it has been unclear how individual migrating cells respond to Reelin. In our opinion, many published results might be explained if Reelin acts on neurons when their leading processes reach the marginal zone. Reelin then stimulates two parallel events: detachment from radial glia and translocation of the cell soma to the top of the developing cortical plate. This 'detach and go' model explains many aspects of inside-out lamination, defects in the Reeler mutant and results of recent genetic and in utero experiments.
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Affiliation(s)
- Jonathan A Cooper
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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20
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Feng L, Allen NS, Simo S, Cooper JA. Cullin 5 regulates Dab1 protein levels and neuron positioning during cortical development. Genes Dev 2008; 21:2717-30. [PMID: 17974915 DOI: 10.1101/gad.1604207] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Many laminated regions of the mammalian brain develop by the migration of neuronal precursor cells, whose final positions are coordinated by signals from the secreted molecule Reelin. Early events in Reelin signaling have been identified, but the mechanism of signal down-regulation has been unclear. A possible source of negative feedback is the Reelin-induced degradation of the critical intracellular signaling component, Disabled-1 (Dab1). Here we show that degradation of Dab1 depends on Dab1 phosphorylation at specific tyrosine residues and on the E3 ubiquitin ligase component Cullin 5 (Cul5). Cul5 forms complexes with SOCS (suppressors of cytokine signaling) proteins, which bind to phosphorylated Dab1 and target it for degradation in tissue culture cells. Ablation of Cul5 in migrating neurons causes an accumulation of active Dab1 protein and a unique cortical layering defect, characterized by excess migration and buildup of neurons at the top of the cortical plate. The results implicate Cul5 and SOCS proteins in down-regulation of Dab1 in vivo and show that Cul5 plays an essential role in regulating neuron migrations during cortical development, possibly by opposing a promigratory effect of Dab1.
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Affiliation(s)
- Libing Feng
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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21
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Sato Y, Taoka M, Sugiyama N, Kubo KI, Fuchigami T, Asada A, Saito T, Nakajima K, Isobe T, Hisanaga SI. Regulation of the interaction of Disabled-1 with CIN85 by phosphorylation with Cyclin-dependent kinase 5. Genes Cells 2007; 12:1315-27. [DOI: 10.1111/j.1365-2443.2007.01139.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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22
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MacLaurin SA, Krucker T, Fish KN. Hippocampal dendritic arbor growth in vitro: regulation by Reelin-Disabled-1 signaling. Brain Res 2007; 1172:1-9. [PMID: 17825270 PMCID: PMC2094008 DOI: 10.1016/j.brainres.2007.07.035] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 07/10/2007] [Accepted: 07/12/2007] [Indexed: 11/15/2022]
Abstract
The cytoplasmic adaptor protein Disabled-1 (Dab1), which is a key component of the Reelin-signaling pathway, has been suggested to be required for neuronal dendritic development. However, only data from studies on immature cultures [< or = 6 days in vitro (DIV)] and cytoarchitectural analyses of mutant mice have been used to formulate this hypothesis. Therefore, to determine if Reelin-Dab1 signaling is specifically required for neurons to develop mature dendrites in respect to length and complexity, we analyzed dendritic development in mature cultures derived from Dab1 knockout (ko) embryos. No significant differences in dendritic length or complexity between Dab1 ko and wt cultures were found at 20 DIV. An examination of dendritic development in maturing cultures found significant differences in dendritic length between mutant and wt cultures at 4 DIV, but detected no differences in complexity. In addition, by 7 DIV, all measures were statistically the same between cultures. Therefore, although Reelin-Dab1 signaling promotes hippocampal dendrite development, Dab1 is not required for neurons to reach maturity with respect to dendritic length and complexity. Furthermore, analyses of 4 DIV cultures derived from Dab1 heterozygotes or mice that express only the natural splice form of Dab1 (p45) found that Dab1(p45/-) hemizygote, but not Dab1(p45/p45) and Dab1 heterozygote cultures had significantly shorter dendrites than those in wt cultures. Thus, a substantial attenuation of the Reelin-Dab1 signal is required before dendrite elongation is significantly decreased at 4 DIV. Moreover, experiments that incorporated a Reelin-neutralizing antibody support the hypothesis that the role(s) Reelin-signaling plays in dendritic maturation is different than the one it has in neuronal positioning.
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Affiliation(s)
- Sarah A MacLaurin
- Novartis Institutes for BioMedical Research, Inc. Cambridge, MA 02139, USA
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23
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Abstract
Disabled1 (DAB1) is an intracellular mediator of the Reelin-signaling pathway and essential for correct neuronal positioning during brain development. So far, DAB1 has been considered a cytoplasmic protein. Here, we show that DAB1 is subject to nucleocytoplasmic shuttling. In its steady state, DAB1 is mainly located in the cytoplasm. However, treatment with leptomycine B, a specific inhibitor of the CRM1 (chromosomal region maintenance 1)-RanGTP-dependent nuclear export, resulted in nuclear accumulation of DAB1. By using deletion or substitutional mutants of DAB1 fused with enhanced green fluorescent protein, we have mapped a bipartite nuclear localization signal and two CRM1-dependent nuclear export signals. These targeting signals were functional in both Neuro2a cells and primary cerebral cortical neurons. Using purified recombinant proteins, we have shown that CRM1 binds to DAB1 directly in a RanGTP-dependent manner. We also show that tyrosine phosphorylation of DAB1, which is indispensable for the layer formation of the brain, by Fyn tyrosine kinase or Reelin stimulation did not affect the subcellular localization of DAB1 in vitro. These results suggest that DAB1 is a nucleocytoplasmic shuttling protein and raise the possibility that DAB1 plays a role in the nucleus as well as in the cytoplasm.
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Affiliation(s)
- Takao Honda
- Department of Anatomy, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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24
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Hoe HS, Pocivavsek A, Dai H, Chakraborty G, Harris DC, Rebeck GW. Effects of apoE on neuronal signaling and APP processing in rodent brain. Brain Res 2006; 1112:70-9. [PMID: 16905123 DOI: 10.1016/j.brainres.2006.07.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 06/14/2006] [Accepted: 07/04/2006] [Indexed: 11/26/2022]
Abstract
We previously reported that primary neuronal cells treated with apolipoprotein E (apoE) or an apoE-derived peptide (EP) increased ERK activation and decreased JNK activation via apoE receptors. Here, we examined if the effects observed in vitro were observed in vivo. Similar to our observations in primary neurons, in vivo we found that injections of 2muM EP into the rat hippocampus increased the levels of ERK activation and decreased JNK activation. However, the time course of these effects was slower in vivo. Immunohistochemical analysis of the tissue showed prominently increased ERK phosphorylation and decreased JNK phosphorylation in neuronal cells throughout the hippocampus, particularly in the CA3 regions. To determine if apoE was endocytosed by neurons, we conjugated fluorescent microspheres with the EP and injected them into the rat hippocampus. After 7 days, the microspheres were present in neurons. We also examined the in vivo effects of apoE on ApoEr2 and APP processing. EP and full-length apoE3 and apoE4 increased C-terminal fragments of ApoEr2 and APP after a single injection, multiple injections, and chronic infusion paradigms. ApoE3 produced higher levels of ApoEr2 and APP C-terminal fragments than apoE4. These results demonstrate that apoE alters ApoEr2 and APP processing in vivo. The increase in ERK activation is consistent with a role for apoE in a neuronal response to stress, and the decrease in JNK activation suggests that apoE may have anti-apoptotic effects, over several days.
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Affiliation(s)
- Hyang-Sook Hoe
- Department of Neuroscience, Georgetown University, 3970 Reservoir Road NW, Washington, DC 20057-1464, USA
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25
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Costagli A, Felice B, Guffanti A, Wilson SW, Mione M. Identification of alternatively spliced dab1 isoforms in zebrafish. Dev Genes Evol 2006; 216:291-9. [PMID: 16520940 PMCID: PMC2790411 DOI: 10.1007/s00427-005-0052-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 12/06/2005] [Indexed: 11/28/2022]
Abstract
We have investigated the genomic organization, the occurrence of alternative splicing and the differential expression of the zebrafish disabled1 (dab1) gene. Dab1 is a key effector of the Reelin pathway, which regulates neuronal migration during brain development in vertebrates. The coding region of the zebrafish dab1 gene spans over 600 kb of genomic DNA and is composed of 15 exons. Alternative splicing in a region enriched for tyrosine residues generates at least three different isoforms. These isoforms are developmentally regulated and show differential tissue expression. Comparison with mouse and human data shows an overall conservation of the genomic organization with different alternative splicing events generating species-specific isoforms. Because these alternative splicing events give rise to isoforms with different numbers of phosphorylateable tyrosines, we speculate that alternative splicing of the dab1 gene in zebrafish and in other vertebrates regulates the nature of the cellular response to the Reelin signal.
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Affiliation(s)
- Arianna Costagli
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
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26
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Ohshima T, Suzuki H, Morimura T, Ogawa M, Mikoshiba K. Modulation of Reelin signaling by Cyclin-dependent kinase 5. Brain Res 2006; 1140:84-95. [PMID: 16529723 DOI: 10.1016/j.brainres.2006.01.121] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/22/2006] [Accepted: 01/30/2006] [Indexed: 10/24/2022]
Abstract
The Reelin signaling and Cyclin-dependent kinase 5 (Cdk5) both regulate neuronal positioning in the developing brain. Using double-transgenic mice, we have previously shown that these two signaling pathways lie in parallel fashion and have a genetic interaction. Disabled-1 (Dab1), an adapter protein, mediates Reelin signaling and becomes tyrosine-phosphorylated on the binding of Reelin to its receptors. Several isoforms of Dab1 are expressed in embryonic mouse brain, and p80 [Dab1(555)] is the major protein translated. In the present study, we investigated whether Cdk5-mediated phosphorylation of Dab1 modulates Reelin signaling. Cdk5 phosphorylates p80 Dab1 at multiple sites in its carboxyl-terminal region, and tyrosine phosphorylation of p80 Dab1 by Fyn tyrosine kinase is attenuated by this Cdk5-mediated phosphorylation in vitro. Tyrosine phosphorylation of p80 Dab1 induced by exogenous Reelin is enhanced in Cdk5-deficient neurons, corroborating the inhibitory effect of Cdk5-mediated Ser/Thr phosphorylation on tyrosine phosphorylation of p80 Dab1. Another isoform, p45 Dab1 [Dab1(271)], however, is phosphorylated by Cdk5 at one serine residue within a unique carboxyl-terminal region, and its serine phosphorylation enhances tyrosine phosphorylation by Fyn and results in progressive degradation of p45 Dab1. These results indicate that Cdk5 modulates Reelin signaling through the Ser/Thr phosphorylation of Dab1 differently in an isoform-specific manner.
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Affiliation(s)
- Toshio Ohshima
- Laboratory for Developmental Neurobiology, Brain Science Institute, RIKEN, Wako, Saitama, Japan.
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27
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Förster E, Jossin Y, Zhao S, Chai X, Frotscher M, Goffinet AM. Recent progress in understanding the role of Reelin in radial neuronal migration, with specific emphasis on the dentate gyrus. Eur J Neurosci 2006; 23:901-9. [PMID: 16519655 DOI: 10.1111/j.1460-9568.2006.04612.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Ten years following identification of Reelin as the product of the gene mutated in reeler mice, the signalling pathway activated by Reelin is being progressively unravelled with the identification of lipoprotein receptors as reelin receptors, of the Dab1 adapter and of some other proximal components in target cells. However, we are still a long way from understanding the action of this complex protein during brain development and maturation. The present review is organized in two parts. First, we summarize our present understanding of Reelin signalling. Then, we review critically some cell biological mechanisms for the action of Reelin based on recent studies on the development of the dentate gyrus, which has proved an extremely useful and tractable model system.
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Affiliation(s)
- Eckart Förster
- Institut für Anatomie und Zellbiologie, Albert-Ludwigs-Universität Freiburg, Albertstr. 17, D-79104 Freiburg, Germany
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28
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Xu M, Arnaud L, Cooper JA. Both the phosphoinositide and receptor binding activities of Dab1 are required for Reelin-stimulated Dab1 tyrosine phosphorylation. ACTA ACUST UNITED AC 2006; 139:300-5. [PMID: 16046028 PMCID: PMC1373784 DOI: 10.1016/j.molbrainres.2005.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Revised: 06/06/2005] [Accepted: 06/07/2005] [Indexed: 01/22/2023]
Abstract
Reelin-stimulated tyrosine phosphorylation of the Dab1 adaptor protein is required during brain development for Reelin-dependent neuron positioning in the cerebral cortex and various other laminated regions. Dab1 contains an amino-terminal PTB/PI domain through which it can bind to Reelin receptors and membrane phosphoinositides. The relative contributions of these binding activities were unknown. Here, we identify a mutation in the PTB domain of Dab1 that inhibits membrane localization without inhibiting receptor binding. In neurons, this mutation reduces both basal and Reelin-stimulated Dab1 tyrosine phosphorylation. In contrast, a mutation that inhibits receptor binding reduces Reelin-stimulated but not basal tyrosine phosphorylation. These results support a model in which phospholipids recruit Dab1 to membranes but do not play a direct role in relaying the Reelin signal, while direct Dab1-receptor interaction is responsible for relaying the Reelin signal but not for membrane recruitment.
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Affiliation(s)
- Mei Xu
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center (FHCRC), 1100 Fairview Avenue North, Seattle, WA 98109, USA
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29
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Affiliation(s)
- Gabriella D'Arcangelo
- The Cain Foundation Laboratories, Texas Children's Hospital, Department of Pediatrics, Program in Developmental Biology, Baylor College of Medicine, Houston 77030, USA
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30
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Bock HH, Jossin Y, May P, Bergner O, Herz J. Apolipoprotein E Receptors Are Required for Reelin-induced Proteasomal Degradation of the Neuronal Adaptor Protein Disabled-1. J Biol Chem 2004; 279:33471-9. [PMID: 15175346 DOI: 10.1074/jbc.m401770200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cytoplasmic adaptor protein Disabled-1 (Dab1) is necessary for the regulation of neuronal positioning in the developing brain by the secreted molecule Reelin. Binding of Reelin to the neuronal apolipoprotein E receptors apoER2 and very low density lipoprotein receptor induces tyrosine phosphorylation of Dab1 and the subsequent activation or relocalization of downstream targets like phosphatidylinositol 3 (PI3)-kinase and Nckbeta. Disruption of Reelin signaling leads to the accumulation of Dab1 protein in the brains of genetically modified mice, suggesting that Reelin limits its own action in responsive neurons by down-regulating the levels of Dab1 expression. Here, we use cultured primary embryonic neurons as a model to demonstrate that Reelin treatment targets Dab1 for proteolytic degradation by the ubiquitin-proteasome pathway. We show that tyrosine phosphorylation of Dab1 but not PI3-kinase activation is required for its proteasomal targeting. Genetic deficiency in the Dab1 kinase Fyn prevents Dab1 degradation. The Reelin-induced Dab1 degradation also depends on apoER2 and very low density lipoprotein receptor in a gene-dose dependent manner. Moreover, pharmacological blockade of the proteasome prevents the formation of a proper cortical plate in an in vitro slice culture assay. Our results demonstrate that signaling through neuronal apoE receptors can activate the ubiquitin-proteasome machinery, which might have implications for the role of Reelin during neurodevelopment and in the regulation of synaptic transmission.
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Affiliation(s)
- Hans H Bock
- Department of Medicine II, Albert-Ludwigs-Universität, Albertstrasse 23, 79104 Freiburg, Germany.
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31
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Herrick TM, Cooper JA. High affinity binding of Dab1 to Reelin receptors promotes normal positioning of upper layer cortical plate neurons. ACTA ACUST UNITED AC 2004; 126:121-8. [PMID: 15249135 DOI: 10.1016/j.molbrainres.2004.03.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2004] [Indexed: 11/21/2022]
Abstract
The positions of neurons in the neocortex, hippocampus, cerebellum and various other laminated brain regions are regulated by a signaling pathway initiated by the secreted protein Reelin and requiring the intracellular adaptor protein Dab1. Dab1 and the Reelin receptors VLDLR and ApoER2 are expressed by neurons whose migrations are coordinated by Reelin. In vitro, Dab1 binds with high affinity to the cytoplasmic tails of VLDLR and ApoER2 via its PTB domain. To test the importance of Dab1 binding to VLDLR and ApoER2, we replaced the Dab1 gene with a cDNA cassette encoding a point mutant allele, Dab1(F158V). This mutation strongly decreases Dab1 binding in vitro to peptides containing the ApoER2 or VLDLR cytoplasmic regions. Surprisingly, Dab1(F158V/F158V) homozygotes have no discernable phenotype. However, Dab1(F158V/-) hemizygous animals have a subtle phenotype in which late-generated cortical plate neurons migrate excessively into the marginal zone. Early cortical plate neurons, subplate neurons, hippocampal pyramidal cells and cerebellar Purkinje cells are positioned normally. Thus Dab(F158V) is a weak loss-of-function (hypomorphic) allele that has no detectable effect when homozygous. The phenotype of Dab1(F158V/-) hemizygotes shows that late cortical plate neurons of layers 2-3 require efficient Reelin-Dab1 signaling to prevent them entering the marginal zone. The Dab1(F158V) allele adds to a series of Dab1 alleles that demonstrates cell type-specific variation in the Reelin-Dab1 pathway.
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Affiliation(s)
- Tara M Herrick
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA 98109, USA
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Ballif BA, Arnaud L, Arthur WT, Guris D, Imamoto A, Cooper JA. Activation of a Dab1/CrkL/C3G/Rap1 pathway in Reelin-stimulated neurons. Curr Biol 2004; 14:606-10. [PMID: 15062102 DOI: 10.1016/j.cub.2004.03.038] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Accepted: 02/17/2004] [Indexed: 11/27/2022]
Abstract
During brain development, many neurons migrate long distances before settling and differentiating. These migrations are coordinated to ensure normal development. The secreted protein Reelin controls the locations of many types of neurons, and its absence causes the classic "Reeler" phenotype. Reelin action requires tyrosine phosphorylation of the intracellular protein Dab1 by Src-family kinases. However, little is known about signaling pathways downstream of Dab1. Here, we identify several proteins in embryonic brain extract that bind to tyrosine-phosphorylated, but not non-phosphorylated, Dab1. Of these, the Crk-family proteins (CrkL, CrkI, and CrkII ), bind significant quantities of Dab1 when embryonic cortical neurons are exposed to Reelin. CrkL binding to Dab1 involves two tyrosine phosphorylation sites, Y220 and 232, that are critical for proper positioning of migrating cortical plate neurons. CrkL also binds C3G, an exchange factor (GEF) for the small GTPase Rap1 that is activated in other systems by tyrosine phosphorylation. We report that Reelin stimulates tyrosine phosphorylation of C3G and activates Rap1. C3G and Rap1 regulate adhesion of fibroblasts and other cell types. Regulation of Crk/CrkL, C3G, and Rap1 by Reelin may be involved in coordinating neuron migrations during brain development.
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Affiliation(s)
- Bryan A Ballif
- Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA.
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33
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Katyal S, Godbout R. Alternative splicing modulates Disabled-1 (Dab1) function in the developing chick retina. EMBO J 2004; 23:1878-88. [PMID: 15057276 PMCID: PMC394239 DOI: 10.1038/sj.emboj.7600185] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Accepted: 03/04/2004] [Indexed: 11/10/2022] Open
Abstract
The Reelin-Disabled 1 (Dab1)-signaling pathway plays a critical role in neuronal cell positioning in the brain. We have isolated two alternatively spliced variants of Dab1 from chick retina, an early form (chDab1-E) expressed in undifferentiated cells and a late form (chDab1-L) expressed in amacrine and ganglion cells. A key difference between the two forms is the exclusion in chDab1-E of two Src-related tyrosine kinase recognition sites implicated in Reelin-mediated Dab1 tyrosine phosphorylation. Retinal cultures transfected with a chDab1-L expression construct undergo a dramatic change in morphology, accompanied by the formation of numerous thin elongated processes, increased tyrosine phosphorylation, activation of Src family kinase(s) and increased levels of the axonal outgrowth protein growth-associated protein-43. In contrast, chDab1-E transfectants retain an undifferentiated morphology. Mutational analysis implicates a specific tyrosine (tyr-198) in the morphological and biochemical alterations associated with chDab1-L expression. We propose that alternative splicing of chDab1 represents an effective and flexible way of regulating the Reelin-Dab1-signaling pathway in a mixed cell population, by ensuring that secreted Reelin activates the signaling cascade only in target neuronal cells.
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Affiliation(s)
- Sachin Katyal
- Department of Oncology, Cross Cancer Institute, University of Alberta, Alberta, Canada
| | - Roseline Godbout
- Department of Oncology, Cross Cancer Institute, University of Alberta, Alberta, Canada
- Department of Oncology, Cross Cancer Institute, University of Alberta, 11560 University Avenue, CDN-Edmonton, Alberta, Canada T6G 1Z2. Tel.: +1 780 432 8901; Fax: +1 780 432 8892; E-mail:
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Ballif BA, Arnaud L, Cooper JA. Tyrosine phosphorylation of Disabled-1 is essential for Reelin-stimulated activation of Akt and Src family kinases. ACTA ACUST UNITED AC 2004; 117:152-9. [PMID: 14559149 DOI: 10.1016/s0169-328x(03)00295-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Reelin is a large secreted signaling protein that is essential for proper positioning of migratory neurons during mammalian brain development. The Reelin signal is transduced into the cell by the lipoprotein receptors VLDLR and ApoER2, leading to tyrosine phosphorylation of the associated intracellular adaptor protein Disabled-1 (Dab1). Tyrosine phosphorylation of Dab1 is essential for responding to Reelin, as knock-in mice expressing a form of Dab1 that cannot be phosphorylated on tyrosine are indistinguishable from mice lacking Reelin, Reelin-receptors or Dab1. Molecular events dependent on Dab1 tyrosine phosphorylation are unknown. However, Reelin has recently been shown to activate the phosphoinositide-3-kinase (PI 3-K)-dependent kinase, Akt, as well as Src family kinases in wild type but not Dab1-/- primary embryonic neuronal cultures. Using pharmacological inhibitors and mice harboring mutant alleles of Dab1, we show here that tyrosine phosphorylation, but not the carboxyl-terminal region, of Dab1 is required for Reelin-induced activation of Akt and Src family kinases. Additionally, although Fyn is an important regulator of Dab1, Fyn deficiency does not prevent acute Reelin-induced Akt activation. Finally, whereas a number of growth factors propagate signals simultaneously through PI 3-K and mitogen-activated protein kinase (MAPK) cascades, we find Reelin does not engage the canonical MAPK cascade. These results define the first molecular events strictly dependent on Reelin-induced Dab1 tyrosine phosphorylation, and suggest that propagation of the Reelin signal is mediated by Akt, substrates of Src family kinases and/or unidentified molecules that share with these a common molecular link to phosphorylated Dab1.
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Affiliation(s)
- Bryan A Ballif
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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Arnaud L, Ballif BA, Cooper JA. Regulation of protein tyrosine kinase signaling by substrate degradation during brain development. Mol Cell Biol 2004; 23:9293-302. [PMID: 14645539 PMCID: PMC309695 DOI: 10.1128/mcb.23.24.9293-9302.2003] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Disabled-1 (Dab1) is a cytoplasmic adaptor protein that regulates neuronal migrations during mammalian brain development. Dab1 function in vivo depends on tyrosine phosphorylation, which is stimulated by extracellular Reelin and requires Src family kinases. Reelin signaling also negatively regulates Dab1 protein levels in vivo, and reduced Dab1 levels may be part of the mechanism that regulates neuronal migration. We have made use of mouse embryo cortical neuron cultures in which Reelin induces Dab1 tyrosine phosphorylation and Src family kinase activation. We have found that Dab1 is normally stable, but in response to Reelin it becomes polyubiquitinated and degraded via the proteasome pathway. We have established that tyrosine phosphorylation of Dab1 is required for its degradation. Dab1 molecules lacking phosphotyrosine are not degraded in neurons in which the Dab1 degradation pathway is active. The requirements for Reelin-induced degradation of Dab1 in vitro correctly predict Dab1 protein levels in vivo in different mutant mice. We also provide evidence that Dab1 serine/threonine phosphorylation may be important for Dab1 tyrosine phosphorylation. Our data provide the first evidence for how Reelin down-regulates Dab1 protein expression in vivo. Dab1 degradation may be important for ensuring a transient Reelin response and may play a role in normal brain development.
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Affiliation(s)
- Lionel Arnaud
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA
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36
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Bock HH, Jossin Y, Liu P, Förster E, May P, Goffinet AM, Herz J. Phosphatidylinositol 3-kinase interacts with the adaptor protein Dab1 in response to Reelin signaling and is required for normal cortical lamination. J Biol Chem 2003; 278:38772-9. [PMID: 12882964 DOI: 10.1074/jbc.m306416200] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reelin is a large secreted signaling protein that binds to two members of the low density lipoprotein receptor family, the apolipoprotein E receptor 2 and the very low density lipoprotein receptor, and regulates neuronal positioning during brain development. Reelin signaling requires activation of Src family kinases as well as tyrosine phosphorylation of the intracellular adaptor protein Disabled-1 (Dab1). This results in activation of phosphatidylinositol 3-kinase (PI3K), the serine/threonine kinase Akt, and the inhibition of glycogen synthase kinase 3beta, a protein that is implicated in the regulation of axonal transport. Here we demonstrate that PI3K activation by Reelin requires Src family kinase activity and depends on the Reelin-triggered interaction of Dab1 with the PI3K regulatory subunit p85alpha. Because the Dab1 phosphotyrosine binding domain can interact simultaneously with membrane lipids and with the intracellular domains of apolipoprotein E receptor 2 and very low density lipoprotein receptor, Dab1 is preferentially recruited to the neuronal plasma membrane, where it is phosphorylated. Efficient Dab1 phosphorylation and activation of the Reelin signaling cascade is impaired by cholesterol depletion of the plasma membrane. Using a neuronal migration assay, we also show that PI3K signaling is required for the formation of a normal cortical plate, a step that is dependent upon Reelin signaling.
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Affiliation(s)
- Hans H Bock
- Department of Molecular Genetics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9046, USA
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Affiliation(s)
- Fadel Tissir
- Developmental Genetics Unit, Université Catholique de Louvain, UCL 7382, 73 Avenue E. Mounier, B1200 Brussels, Belgium
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Benhayon D, Magdaleno S, Curran T. Binding of purified Reelin to ApoER2 and VLDLR mediates tyrosine phosphorylation of Disabled-1. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 112:33-45. [PMID: 12670700 DOI: 10.1016/s0169-328x(03)00032-9] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Reelin, Disabled-1 (Dab1), apolipoprotein E receptor 2 (ApoER2), and very low density lipoprotein receptor (VLDLR) participate in a signaling pathway required for layer formation during mammalian brain development. Binding of Reelin to ApoER2 and VLDLR induces a rapid increase in tyrosine phosphorylation of Dab1, an adaptor protein that associates with the cytoplasmic domain of the receptors. However, Reelin has also been proposed to signal through integrin and protocadherin. Here we compare the roles of ApoER2 and VLDLR in Reelin signaling. We used layer-specific markers to identify the final positions of early- and late-born neurons in the cortices of mice lacking ApoER2, VLDLR, or both ApoER2 and VLDLR. Subtle alterations were observed in mice lacking VLDLR, whereas more severe abnormalities were detected in the absence of ApoER2, and major disruptions were obvious in mice lacking both receptors. Purified Reelin associated more readily with ApoER2 than with VLDLR and no synergy was observed in the presence of both receptors. Consistent with the binding data, the level of Reelin-induced Dab1 phosphorylation was more severely reduced in neurons lacking ApoER2 than in neurons lacking VLDLR. However, similarly low levels of Dab1 tyrosine phosphorylation were observed in ApoER2(-/-) and VLDLR(-/-) mice in vivo. Finally, there was a complete absence of Reelin-induced tyrosine phosphorylation of Dab1 in cortical neurons from mice lacking both ApoER2 and VLDLR. These findings demonstrate that ApoER2 and VLDLR are essential for Reelin signaling and that no other receptor molecules can compensate for their role in mediating tyrosine phosphorylation of Dab1.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Cell Adhesion Molecules, Neuronal/metabolism
- Cell Adhesion Molecules, Neuronal/pharmacology
- Cell Differentiation/genetics
- Cell Movement/genetics
- Cells, Cultured
- Cerebral Cortex/abnormalities
- Cerebral Cortex/cytology
- Cerebral Cortex/metabolism
- Dose-Response Relationship, Drug
- Extracellular Matrix Proteins/metabolism
- Extracellular Matrix Proteins/pharmacology
- Female
- Fetus
- LDL-Receptor Related Proteins
- Mice
- Mice, Knockout
- Nerve Tissue Proteins/metabolism
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Phosphorylation
- Protein Binding/genetics
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Receptors, Lipoprotein/deficiency
- Receptors, Lipoprotein/genetics
- Reelin Protein
- Serine Endopeptidases
- Tyrosine/metabolism
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Affiliation(s)
- David Benhayon
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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Bar I, Tissir F, Lambert de Rouvroit C, De Backer O, Goffinet AM. The gene encoding disabled-1 (DAB1), the intracellular adaptor of the Reelin pathway, reveals unusual complexity in human and mouse. J Biol Chem 2003; 278:5802-12. [PMID: 12446734 DOI: 10.1074/jbc.m207178200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Disabled-1 (Dab1) gene encodes a key regulator of Reelin signaling. Reelin is a large glycoprotein secreted by neurons of the developing brain, particularly Cajal-Retzius cells. The DAB1 protein docks to the intracellular part of the Reelin very low density lipoprotein receptor and apoE receptor type 2 and becomes tyrosine-phosphorylated following binding of Reelin to cortical neurons. In mice, mutations of Dab1 and Reelin generate identical phenotypes. In humans, Reelin mutations are associated with brain malformations and mental retardation; mutations in DAB1 have not been identified. Here, we define the organization of Dab1, which is similar in human and mouse. The Dab1 gene spreads over 1100 kb of genomic DNA and is composed of 14 exons encoding the major protein form, some alternative internal exons, and multiple 5'-exons. Alternative polyadenylation and splicing events generate DAB1 isoforms. Several 5'-untranslated regions (UTRs) correspond to different promoters. Two 5'-UTRs (1A and 1B) are predominantly used in the developing brain. 5'-UTR 1B is composed of 10 small exons spread over 800 kb. With a genomic length of 1.1 Mbp for a coding region of 5.5 kb, Dab1 provides a rare example of genomic complexity, which will impede the identification of human mutations.
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Affiliation(s)
- Isabelle Bar
- Neurobiology Unit, University of Namur Medical School, 61, rue de Bruxelles, B5000 Namur, Belgium.
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40
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Abstract
Lissencephaly, which means 'smooth cortex', is caused by defective neuronal migration during development of the cerebral cortex and has devastating clinical consequences. 'Classical' lissencephaly seems to reflect mutations in regulators of the microtubule cytoskeleton, whereas 'cobblestone' lissencephaly is caused by mutations in genes needed for the integrity of the basal lamina of the central nervous system. Reelin, which is mutated in a third type of lissencephaly, may represent a unifying link because it encodes an extracellular protein that regulates neuronal migration and may also regulate the microtubule cytoskeleton.
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Affiliation(s)
- Eric C Olson
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA
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Morris SM, Arden SD, Roberts RC, Kendrick-Jones J, Cooper JA, Luzio JP, Buss F. Myosin VI binds to and localises with Dab2, potentially linking receptor-mediated endocytosis and the actin cytoskeleton. Traffic 2002; 3:331-41. [PMID: 11967127 DOI: 10.1034/j.1600-0854.2002.30503.x] [Citation(s) in RCA: 209] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Myosin VI, an actin-based motor protein, and Disabled 2 (Dab2), a molecule involved in endocytosis and cell signalling, have been found to bind together using yeast and mammalian two-hybrid screens. In polarised epithelial cells, myosin VI is known to be associated with apical clathrin-coated vesicles and is believed to move them towards the minus end of actin filaments, away from the plasma membrane and into the cell. Dab2 belongs to a group of signal transduction proteins that bind in vitro to the FXNPXY sequence found in the cytosolic tails of members of the low-density lipoprotein receptor family. The central region of Dab2, containing two DPF motifs, binds to the clathrin adaptor protein AP-2, whereas a C-terminal region contains the binding site for myosin VI. This site is conserved in Dab1, the neuronal counterpart of Dab2. The interaction between Dab2 and myosin VI was confirmed by in vitro binding assays and coimmunoprecipitation and by their colocalisation in clathrin-coated pits/vesicles concentrated at the apical domain of polarised cells. These results suggest that the myosin VI-Dab2 interaction may be one link between the actin cytoskeleton and receptors undergoing endocytosis.
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Affiliation(s)
- Shelli M Morris
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, 1100 Fairview Avenue North, Seattle, WA 98109-1024, USA
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