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Muralidharan N, Murugan A, Raj PA, Jothi M. Restoration of functional PAX3 transcriptional factor enhanced neuronal differentiation in PAX3b isoform-depleted neuroblastoma cells. Cell Tissue Res 2023; 391:55-65. [PMID: 36378335 DOI: 10.1007/s00441-022-03710-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022]
Abstract
Reexpressed PAX3 transcription factor is believed to be responsible for the differentiation defects observed in neuroblastoma. Although the importance of PAX3 in neuronal differentiation is documented how it is involved in the defective differentiation remains unexplored particularly with its isoforms. Here, first we have analyzed PAX3 expression, its functional status, and its correlation with the neuronal marker expression in SH-SY5Y and its parental SK-N-SH cells. We have found that SH-SY5Y cells which expressed more PAX3 showed increased expression of neuronal marker genes (TUBB, MAP2, NEFL, NEUROG2, SYP) and reported PAX3 target genes (MET, TGFA, and NCAM1) than the SK-N-SH cells that had low PAX3 level. Retinoic acid treatment is unable to induce neuronal differentiation in cells (SK-N-SH) with low PAX3 level/activity. Moreover, ectopic expression of PAX3 in SK-N-SH cells neither induces neuronal marker genes nor its target genes. PAX3 isoform expression analysis revealed the expression of PAX3b isoform that contains only paired domain in SK-N-SH cells, whereas in SH-SY5Y cells, we could also observe PAX3c isoform that contains all functional domains. Further, PAX3b depletion in SK-N-SH cells is not induced PAX3 target genes, and the cells remain poorly differentiated. Interestingly, ectopic PAX3 expression in PAX3b-depleted SK-N-SH cells enhanced neuronal outgrowth along with neuronal marker gene induction. Collectively, these results showed that the PAX3b isoform may be responsible for the differentiation defect observed in SK-N-SH cells and restoration of functional PAX3 in the absence of PAX3b can induce neurogenesis in these cells.
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Affiliation(s)
- Narenkumar Muralidharan
- Laboratory of Molecular Therapeutics, Department of Human Genetics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, Karnataka, India
| | - Abinayaselvi Murugan
- Laboratory of Molecular Therapeutics, Department of Human Genetics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, Karnataka, India
| | - Prabhuraj Andiperumal Raj
- Department of Neurosurgery, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, Karnataka, India
| | - Mathivanan Jothi
- Laboratory of Molecular Therapeutics, Department of Human Genetics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, Karnataka, India.
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Zhou J, Liu G, Zhang X, Wu C, Ma M, Wu J, Hou L, Yin B, Qiang B, Shu P, Peng X. Comparison of the Spatiotemporal Expression Patterns of Three Cre Lines, Emx1IRES-Cre, D6-Cre and hGFAP-Cre, Commonly Used in Neocortical Development Research. Cereb Cortex 2021; 32:1668-1681. [PMID: 34550336 DOI: 10.1093/cercor/bhab305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/01/2021] [Accepted: 08/02/2021] [Indexed: 11/14/2022] Open
Abstract
Emx1IRES-Cre, D6-Cre and hGFAP-Cre are commonly used to conditionally manipulate gene expression or lineage tracing because of their specificity in the dorsal telencephalon during early neurogenesis as previously described. However, the spatiotemporal differences in Cre recombinase activity would lead to divergent phenotypes. Here, we compared the patterns of Cre activity in the early embryos among the three lines by mating with reporter mice. The activities of Emx1IRES-Cre, D6-Cre and hGFAP-Cre were observed in the dorsal telencephalon, starting from approximately embryonic day 9.5, 11.5 and 12.5, respectively. Although all the three lines have activity in radial glial cells, Emx1IRES-Cre fully covers the dorsal and medial telencephalon, including the archicortex and cortical hem. D6-Cre is highly restricted to the dorsal telencephalon with anterior-low to posterior-high gradients, partially covers the hippocampus, and absent in the cortical hem. Moreover, both Emx1IRES-Cre and hGFAP-Cre exhibit Cre activity outside the dorsal neocortex. Meanwhile, we used the three Cre lines to mediate Dicer knockout and observed inconsistent phenotypes, including discrepancies in radial glial cell number, survival and neurogenesis in the neocortex and hippocampus. Together we proved differences in Cre activity can perturb the resultant phenotypes, which aid researchers in appropriate experimental design.
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Affiliation(s)
- Jiafeng Zhou
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Gaoao Liu
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Xiaoling Zhang
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Chao Wu
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Mengjie Ma
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Jiarui Wu
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Lin Hou
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Bin Yin
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Boqin Qiang
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Pengcheng Shu
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China.,Chinese Institute for Brain Research, Beijing, 102206, China
| | - Xiaozhong Peng
- The State Key Laboratory of Medical Molecular Biology, Neuroscience Center, Medical Primate Research Center and Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China.,Institute of Medical Biology of the Chinese Academy of Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650118, China
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3
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Michalak SM, Whitman MC, Park JG, Tischfield MA, Nguyen EH, Engle EC. Ocular Motor Nerve Development in the Presence and Absence of Extraocular Muscle. Invest Ophthalmol Vis Sci 2017; 58:2388-2396. [PMID: 28437527 PMCID: PMC5403115 DOI: 10.1167/iovs.16-21268] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Purpose To spatially and temporally define ocular motor nerve development in the presence and absence of extraocular muscles (EOMs). Methods Myf5cre mice, which in the homozygous state lack EOMs, were crossed to an IslMN:GFP reporter line to fluorescently label motor neuron cell bodies and axons. Embryonic day (E) 11.5 to E15.5 wild-type and Myf5cre/cre:IslMN:GFP whole mount embryos and dissected orbits were imaged by confocal microscopy to visualize the developing oculomotor, trochlear, and abducens nerves in the presence and absence of EOMs. E11.5 and E18.5 brainstems were serially sectioned and stained for Islet1 to determine the fate of ocular motor neurons. Results At E11.5, all three ocular motor nerves in mutant embryos approached the orbit with a trajectory similar to that of wild-type. Subsequently, while wild-type nerves send terminal branches that contact target EOMs in a stereotypical pattern, the Myf5cre/cre ocular motor nerves failed to form terminal branches, regressed, and by E18.5 two-thirds of their corresponding motor neurons died. Comparisons between mutant and wild-type embryos revealed novel aspects of trochlear and oculomotor nerve development. Conclusions We delineated mouse ocular motor nerve spatial and temporal development in unprecedented detail. Moreover, we found that EOMs are not necessary for initial outgrowth and guidance of ocular motor axons from the brainstem to the orbit but are required for their terminal branching and survival. These data suggest that intermediate targets in the mesenchyme provide cues necessary for appropriate targeting of ocular motor axons to the orbit, while EOM cues are responsible for terminal branching and motor neuron survival.
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Affiliation(s)
- Suzanne M Michalak
- Department of Neurology, Boston Children's Hospital, Boston, Massachusetts, United States 2F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States 3Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States 4University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States 5Howard Hughes Medical Institute, Chevy Chase, Maryland, United States
| | - Mary C Whitman
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States 6Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States 7Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
| | - Jong G Park
- Department of Neurology, Boston Children's Hospital, Boston, Massachusetts, United States 2F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States 3Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States 5Howard Hughes Medical Institute, Chevy Chase, Maryland, United States 8Duke University School of Medicine, Durham, North Carolina, United States
| | - Max A Tischfield
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States 3Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States
| | - Elaine H Nguyen
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States 6Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States
| | - Elizabeth C Engle
- Department of Neurology, Boston Children's Hospital, Boston, Massachusetts, United States 2F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States 3Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States 5Howard Hughes Medical Institute, Chevy Chase, Maryland, United States 6Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States 7Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
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Chilton JK, Guthrie S. Axons get ahead: Insights into axon guidance and congenital cranial dysinnervation disorders. Dev Neurobiol 2017; 77:861-875. [DOI: 10.1002/dneu.22477] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 11/12/2022]
Affiliation(s)
- John K. Chilton
- Wellcome Wolfson Centre for Medical Research; University of Exeter Medical School, Wellcome-Wolfson Centre for Medical Research; Exeter EX2 5DW United Kingdom
| | - Sarah Guthrie
- School of Life Sciences; University of Sussex; Falmer Brighton, BN1 9QG
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Elliott PR, Komander D. Regulation of Met1-linked polyubiquitin signalling by the deubiquitinase OTULIN. FEBS J 2015; 283:39-53. [PMID: 26503766 PMCID: PMC4765238 DOI: 10.1111/febs.13547] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 08/25/2015] [Accepted: 10/02/2015] [Indexed: 12/25/2022]
Abstract
Modification of proteins with Met1‐linked ‘linear’ ubiquitin chains has emerged as a key regulatory signal to control inflammatory signalling via the master regulator, the transcription factor nuclear factor κB (NF‐κB). While the assembly machinery, the linear ubiquitin chain assembly complex (LUBAC), and receptors for this ubiquitin chain type have been known for years, it was less clear which deubiquitinating enzymes (DUBs) hydrolyse Met1 linkages specifically. In 2013, two labs reported the previously unannotated protein FAM105B/OTULIN to be this missing Met1 linkage‐specific DUB. Structural studies have revealed how OTULIN achieves its remarkable specificity, employing a mechanism of ubiquitin‐assisted catalysis in which a glutamate residue on the substrate complements the active site of the enzyme. The specificity of OTULIN enables it to regulate global levels of Met1‐linked polyubiquitin in cells. This ability led to investigations of NF‐κB activation from new angles, and also revealed involvement of Met1‐polyubiquitin in Wnt signalling. Interestingly, OTULIN directly interacts with LUBAC, and this interaction is dynamic and can be regulated by OTULIN phosphorylation. This provides a new paradigm for how individual linkage types can be regulated by dedicated enzyme complexes mediating assembly and removal. Here we review what has been learned about OTULIN's mechanism, regulation and function, discuss the open questions in the field, and discuss how DUBs regulate the NF‐κB response.
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Affiliation(s)
- Paul R Elliott
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - David Komander
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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6
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Ha S, Stottmann RW, Furley AJ, Beier DR. A forward genetic screen in mice identifies mutants with abnormal cortical patterning. ACTA ACUST UNITED AC 2013; 25:167-79. [PMID: 23968836 DOI: 10.1093/cercor/bht209] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Formation of a 6-layered cortical plate and axon tract patterning are key features of cerebral cortex development. Abnormalities of these processes may be the underlying cause for a range of functional disabilities seen in human neurodevelopmental disorders. To identify mouse mutants with defects in cortical lamination or corticofugal axon guidance, N-ethyl-N-nitrosourea (ENU) mutagenesis was performed using mice expressing LacZ reporter genes in layers II/III and V of the cortex (Rgs4-lacZ) or in corticofugal axons (TAG1-tau-lacZ). Four lines with abnormal cortical lamination have been identified. One of these was a splice site mutation in reelin (Reln) that results in a premature stop codon and the truncation of the C-terminal region (CTR) domain of reelin. Interestingly, this novel allele of Reln did not display cerebellar malformation or ataxia, and this is the first report of a Reln mutant without a cerebellar defect. Four lines with abnormal cortical axon development were also identified, one of which was found by whole-genome resequencing to carry a mutation in Lrp2. These findings demonstrated that the application of ENU mutagenesis to mice carrying transgenic reporters marking cortical anatomy is a sensitive and specific method to identify mutations that disrupt patterning of the developing brain.
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Affiliation(s)
- Seungshin Ha
- Genetics Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, University of Washington School of Medicine, Seattle, WA 98101, USA
| | - Rolf W Stottmann
- Genetics Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA Divisions of Human Genetics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA and
| | - Andrew J Furley
- Department of Biomedical Science, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - David R Beier
- Genetics Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, University of Washington School of Medicine, Seattle, WA 98101, USA
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7
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The linear ubiquitin-specific deubiquitinase gumby regulates angiogenesis. Nature 2013; 498:318-24. [PMID: 23708998 PMCID: PMC4931916 DOI: 10.1038/nature12296] [Citation(s) in RCA: 218] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 05/20/2013] [Indexed: 12/26/2022]
Abstract
A complex interplay of signaling events, including the Wnt pathway, regulates sprouting of blood vessels from preexisting vasculature during angiogenesis. Here we show that two distinct mutations in the (uro)chordate-specific Gumby/Fam105b gene cause an embryonic angiogenic phenotype in gumby mice. Gumby interacts with Disheveled 2 (Dvl2), is expressed in canonical Wnt-responsive endothelial cells and encodes an Ovarian Tumor Domain (OTU) class of deubiquitinase (DUB) that specifically cleaves linear ubiquitin linkages. A crystal structure of Gumby in complex with linear di-ubiquitin reveals how the identified mutations adversely impact substrate binding and catalytic function in line with the severity of their angiogenic phenotypes. Gumby interacts with HOIP/Rnf31, a key component of the linear ubiquitin assembly complex (LUBAC), decreases linear ubiquitination and activation of NFκB dependent transcription. This work provides support for the biological importance of linear (de)ubiquitination in angiogenesis, craniofacial and neural development and in modulating Wnt signaling.
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Lance-Jones C, Shah V, Noden DM, Sours E. Intrinsic properties guide proximal abducens and oculomotor nerve outgrowth in avian embryos. Dev Neurobiol 2012; 72:167-85. [PMID: 21739615 DOI: 10.1002/dneu.20948] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Proper movement of the vertebrate eye requires the formation of precisely patterned axonal connections linking cranial somatic motoneurons, located at defined positions in the ventral midbrain and hindbrain, with extraocular muscles. The aim of this research was to assess the relative contributions of intrinsic, population-specific properties and extrinsic, outgrowth site-specific cues during the early stages of abducens and oculomotor nerve development in avian embryos. This was accomplished by surgically transposing midbrain and caudal hindbrain segments, which had been pre-labeled by electroporation with an EGFP construct. Graft-derived EGFP+ oculomotor axons entering a hindbrain microenvironment often mimicked an abducens initial pathway and coursed cranially. Similarly, some EGFP+ abducens axons entering a midbrain microenvironment mimicked an oculomotor initial pathway and coursed ventrally. Many but not all of these axons subsequently projected to extraocular muscles that they would not normally innervate. Strikingly, EGFP+ axons also took initial paths atypical for their new location. Upon exiting from a hindbrain position, most EGFP+ oculomotor axons actually coursed ventrally and joined host branchiomotor nerves, whose neurons share molecular features with oculomotor neurons. Similarly, upon exiting from a midbrain position, some EGFP+ abducens axons turned caudally, elongated parallel to the brainstem, and contacted the lateral rectus muscle, their originally correct target. These data reveal an interplay between intrinsic properties that are unique to oculomotor and abducens populations and shared ability to recognize and respond to extrinsic directional cues. The former play a prominent role in initial pathway choices, whereas the latter appear more instructive during subsequent directional choices.
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Affiliation(s)
- Cynthia Lance-Jones
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
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Focusing forward genetics: a tripartite ENU screen for neurodevelopmental mutations in the mouse. Genetics 2011; 188:615-24. [PMID: 21515572 DOI: 10.1534/genetics.111.126862] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The control of growth, patterning, and differentiation of the mammalian forebrain has a large genetic component, and many human disease loci associated with cortical malformations have been identified. To further understand the genes involved in controlling neural development, we have performed a forward genetic screen in the mouse (Mus musculus) using ENU mutagenesis. We report the results from our ENU screen in which we biased our ascertainment toward mutations affecting neurodevelopment. Our screen had three components: a careful morphological and histological examination of forebrain structure, the inclusion of a retinoic acid response element-lacZ reporter transgene to highlight patterning of the brain, and the use of a genetically sensitizing locus, Lis1/Pafah1b1, to predispose animals to neurodevelopmental defects. We recovered and mapped eight monogenic mutations, seven of which affect neurodevelopment. We have evidence for a causal gene in four of the eight mutations. We describe in detail two of these: a mutation in the planar cell polarity gene scribbled homolog (Drosophila) (Scrib) and a mutation in caspase-3 (Casp3). We find that refining ENU mutagenesis in these ways is an efficient experimental approach and that investigation of the developing mammalian nervous system using forward genetic experiments is highly productive.
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Dwyer ND, Manning DK, Moran JL, Mudbhary R, Fleming MS, Favero CB, Vock VM, O'Leary DDM, Walsh CA, Beier DR. A forward genetic screen with a thalamocortical axon reporter mouse yields novel neurodevelopment mutants and a distinct emx2 mutant phenotype. Neural Dev 2011; 6:3. [PMID: 21214893 PMCID: PMC3024922 DOI: 10.1186/1749-8104-6-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 01/07/2011] [Indexed: 12/02/2022] Open
Abstract
Background The dorsal thalamus acts as a gateway and modulator for information going to and from the cerebral cortex. This activity requires the formation of reciprocal topographic axon connections between thalamus and cortex. The axons grow along a complex multistep pathway, making sharp turns, crossing expression boundaries, and encountering intermediate targets. However, the cellular and molecular components mediating these steps remain poorly understood. Results To further elucidate the development of the thalamocortical system, we first created a thalamocortical axon reporter line to use as a genetic tool for sensitive analysis of mutant mouse phenotypes. The TCA-tau-lacZ reporter mouse shows specific, robust, and reproducible labeling of thalamocortical axons (TCAs), but not the overlapping corticothalamic axons, during development. Moreover, it readily reveals TCA pathfinding abnormalities in known cortical mutants such as reeler. Next, we performed an unbiased screen for genes involved in thalamocortical development using random mutagenesis with the TCA reporter. Six independent mutant lines show aberrant TCA phenotypes at different steps of the pathway. These include ventral misrouting, overfasciculation, stalling at the corticostriatal boundary, and invasion of ectopic cortical cell clusters. An outcross breeding strategy coupled with a genomic panel of single nucleotide polymorphisms facilitated genetic mapping with small numbers of mutant mice. We mapped a ventral misrouting mutant to the Emx2 gene, and discovered that some TCAs extend to the olfactory bulbs in this mutant. Mapping data suggest that other lines carry mutations in genes not previously known for roles in thalamocortical development. Conclusions These data demonstrate the feasibility of a forward genetic approach to understanding mammalian brain morphogenesis and wiring. A robust axonal reporter enabled sensitive analysis of a specific axon tract inside the mouse brain, identifying mutant phenotypes at multiple steps of the pathway, and revealing a new aspect of the Emx2 mutant. The phenotypes highlight vulnerable choice points and latent tendencies of TCAs, and will lead to a refined understanding of the elements and interactions required to form the thalamocortical system. See Commentary: http://www.biomedcentral.com/1741-7007/9/1
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Affiliation(s)
- Noelle D Dwyer
- Howard Hughes Medical Institute, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA.
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A forward genetic screen in mice identifies Sema3A(K108N), which binds to neuropilin-1 but cannot signal. J Neurosci 2010; 30:5767-75. [PMID: 20410128 DOI: 10.1523/jneurosci.5061-09.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have performed a three-generation, forward genetic screen to identify recessive mutations that affect the patterning of the peripheral nervous system. Using this assay, we identified Sema3A(K108N), a novel loss-of-function allele of Sema3A. Class 3 semaphorins, which include Sema3A, are structurally conserved secreted proteins that play critical roles in the development and function of the nervous system. Sema3A(K108N) mutant mice phenocopy Sema3A-null mice, and Sema3A(K108N) protein fails to repel or collapse DRG axons in vitro. K108 is conserved among semaphorins, yet the loss-of-function effects associated with K108N are not the result of impaired expression, secretion, or binding of Sema3A to its high-affinity receptor Neuropilin-1 (Npn-1). Using in silico modeling and mutagenesis of other semaphorin family members, we predict that Sema3A(K108N) interacts poorly with the Npn-1/PlexA holoreceptor and, thus, interferes with its ability to signal at the growth cone. Therefore, through the use of a forward-genetic screen we have identified a novel allele of Sema3A that provides structural insight into the mechanism of Sema3A/Npn-1/PlexinA signaling.
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Tischfield MA, Baris HN, Wu C, Rudolph G, Van Maldergem L, He W, Chan WM, Andrews C, Demer JL, Robertson RL, Mackey DA, Ruddle JB, Bird TD, Gottlob I, Pieh C, Traboulsi EI, Pomeroy SL, Hunter DG, Soul JS, Newlin A, Sabol LJ, Doherty EJ, de Uzcátegui CE, de Uzcátegui N, Collins MLZ, Sener EC, Wabbels B, Hellebrand H, Meitinger T, de Berardinis T, Magli A, Schiavi C, Pastore-Trossello M, Koc F, Wong AM, Levin AV, Geraghty MT, Descartes M, Flaherty M, Jamieson RV, Møller HU, Meuthen I, Callen DF, Kerwin J, Lindsay S, Meindl A, Gupta ML, Pellman D, Engle EC. Human TUBB3 mutations perturb microtubule dynamics, kinesin interactions, and axon guidance. Cell 2010; 140:74-87. [PMID: 20074521 PMCID: PMC3164117 DOI: 10.1016/j.cell.2009.12.011] [Citation(s) in RCA: 413] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 09/11/2009] [Accepted: 11/02/2009] [Indexed: 01/14/2023]
Abstract
We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific beta-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis, and/or later-onset axonal sensorimotor polyneuropathy. Neuroimaging reveals a spectrum of abnormalities including hypoplasia of oculomotor nerves and dysgenesis of the corpus callosum, anterior commissure, and corticospinal tracts. A knock-in disease mouse model reveals axon guidance defects without evidence of cortical cell migration abnormalities. We show that the disease-associated mutations can impair tubulin heterodimer formation in vitro, although folded mutant heterodimers can still polymerize into microtubules. Modeling each mutation in yeast tubulin demonstrates that all alter dynamic instability whereas a subset disrupts the interaction of microtubules with kinesin motors. These findings demonstrate that normal TUBB3 is required for axon guidance and maintenance in mammals.
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Affiliation(s)
- Max A. Tischfield
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- The Manton Center for Orphan Disease Research, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Hagit N. Baris
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115 USA
| | - Chen Wu
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Guenther Rudolph
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Lionel Van Maldergem
- Centre de génétique humaine Université de Liège, Domaine universitaire du Sart-Tilman, B-4000 Liège, Belgium
| | - Wei He
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
| | - Wai-Man Chan
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Caroline Andrews
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Joseph L. Demer
- Department of Ophthalmology and Jules Stein Eye Institute, David Geffen Medical School at University of California Los Angeles
- Department of Neurology, David Geffen Medical School at University of California Los Angeles
- Neuroscience Interdepartmental Program, David Geffen Medical School at University of California Los Angeles
- Bioengineering Interdepartmental Program, David Geffen Medical School at University of California Los Angeles
| | | | - David A. Mackey
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, 3002, Australia
- Department of Ophthalmology, Royal Hobart Hospital, University of Tasmania, Hobart Tasmania, 7000, Australia
| | - Jonathan B. Ruddle
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, 3002, Australia
| | - Thomas D. Bird
- Department of Neurology and the Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
- GRECC, VA Puget Sound Health Care System, Seattle, WA
| | - Irene Gottlob
- Ophthalmology Group, University of Leicester, Leicester, LE2 7LX, UK
| | - Christina Pieh
- University Eye Hospital, University of Freiburg, Killianstr. 6, 79106 Freiburg, Germany
| | - Elias I. Traboulsi
- Cole Eye Institute, Cleveland Clinic i32, 9500 Euclid Avenue Cleveland, OH 44195
| | - Scott L. Pomeroy
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - David G. Hunter
- Department of Ophthalmology, Children’s Hospital Boston, Boston, MA 02115 USA
| | - Janet S. Soul
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Anna Newlin
- Center for Medical Genetics, NorthShore University HealthSystem, Evanston, IL 60201
| | - Louise J. Sabol
- Department of Ophthalmology, Geisinger Medical Institute, Danville, Pennsylvania
| | - Edward J. Doherty
- Atlantic Health Science Centre, Saint John Regional Hospital, Saint John New Brunswick, Canada
| | - Clara E. de Uzcátegui
- Instituto de Oftalmologia, Av. Cajigal 48. Piso 3 Consultorio 8. San Bernardino, Caracas 1010 Venezuela
| | - Nicolas de Uzcátegui
- Department of Ophthalmology, Upstate Medical University SUNY. Eye Consultants Of Syracuse, 1101 Erie Blvd. East Ste 100. Syracuse NY 13210
| | | | - Emin C. Sener
- Department of Ophthalmology, Hacettepe University Hospitals, Ankara 06100, Turkey
| | - Bettina Wabbels
- Department of Ophthalmology, University of Bonn, Abbestr. 2, D-53127, Bonn, Germany
| | - Heide Hellebrand
- Department of Obstetrics and Gynaecology, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr 22, 81675 Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr 22, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Teresa de Berardinis
- Department of Ophthalmologic Sciences, Faculty of Medicine and Surgery, University “Federico II”, Naples, Italy
| | - Adriano Magli
- Department of Ophthalmologic Sciences, Faculty of Medicine and Surgery, University “Federico II”, Naples, Italy
| | | | - Marco Pastore-Trossello
- Department of Neuro-Radiology, S.Orsola-Malpighi Hospital via Albertoni, 15, 40138, Bologna, Italy
| | - Feray Koc
- Department of Ophthalmology and Strabismus, and Neuroophthalmology, Acıbadem University Kocaeli Hospital, Kocaeli 41100 Turkey
| | - Agnes M. Wong
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario Canada
| | - Alex V. Levin
- Pediatric Ophthalmology and Ocular Genetics, Wills Eye Institute, Philadelphia, PA
| | | | - Maria Descartes
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Maree Flaherty
- Department of Ophthalmology, The Children’s Hospital at Westmead, Sydney, Australia
| | - Robyn V. Jamieson
- Department of Clinical Genetics, The Children’s Hospital at Westmead, Sydney, Australia
- The University of Sydney, Sydney, Australia
| | - H. U. Møller
- Department of Ophthalmology, Viborg Hospital, DK 8000 Viborg Denmark
| | - Ingo Meuthen
- Department of Hematology-Oncology, Kliniken der Stadt Köln, Neufelderstr. 32, 51067 Köln, Germany
| | - David F. Callen
- Breast Cancer Genetics Group, School of Medicine, University of Adelaide, Australia
| | - Janet Kerwin
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Susan Lindsay
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
- MRC-Wellcome Trust Human Developmental Biology Resource (Newcastle), Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Alfons Meindl
- Department of Obstetrics and Gynaecology, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr 22, 81675 Munich, Germany
| | - Mohan L. Gupta
- Division of Hematology/Oncology, Harvard Medical School, Boston, MA 02115, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - David Pellman
- Division of Hematology/Oncology, Children’s Hospital Boston, Boston, MA 02115 USA
- Division of Hematology/Oncology, Harvard Medical School, Boston, MA 02115, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Elizabeth C. Engle
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- The Manton Center for Orphan Disease Research, Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Ophthalmology, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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13
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Abstract
The use of mutagenesis in invertebrates to generate phenotypic variants has a long and productive history. Despite the conclusive demonstration by Russell and colleagues in the 1970s that the chemical N-ethyl-N-nitrosourea (ENU) is a highly effective mutagen in mice, the application of phenotypic-driven mutagenesis as a method to study mammalian biology proceeded slowly. With the development of tools for genomic analysis, the task of positional cloning ENU-induced mutations has become quite feasible, and this approach has recently been widely applied and highly productive. It has specifically lived up to its theoretical utility as means to provide insight into the biological roles of genes that is not biased by presumptions of their function. While the power of this approach is indisputable, the effort necessary for its success remains substantial, requiring careful attention to aspects including ENU treatment, mouse husbandry, screen assay design, genetic mapping, positional cloning, and mutation validation. In this chapter we discuss practical aspects of implementing a phenotype-driven analysis of an ENU-mutagenized mouse population.
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14
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Uzumcu A, Candan S, Toksoy G, Uyguner ZO, Karaman B, Eris H, Tatli B, Kayserili H, Yuksel A, Geckinli B, Yuksel-Apak M, Basaran S. Mutational screening of BASP1 and transcribed processed pseudogene TPPsig-BASP1 in patients with Möbius syndrome. J Genet Genomics 2009; 36:251-6. [PMID: 19376485 DOI: 10.1016/s1673-8527(08)60112-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 12/30/2008] [Accepted: 01/21/2009] [Indexed: 11/29/2022]
Abstract
Möbius syndrome is a rare disorder primarily characterized by congenital facial palsy, frequently accompanied by ocular abduction anomalies and occasionally associated with orofacial, limb and musculoskeletal malformations. Abnormal development of cranial nerves V through XII underlines the disease pathogenesis. Although a genetic etiology for Möbius syndrome was proposed, molecular genetic studies to identify the causative gene(s) are scarce. In this study, we selected two candidate genes. One is BASP1 residing in a human chromosome 5p15.1-p15.2, syntenic to mouse chromosome 15qA2-qB2, to which a mouse model with facial nerve anomalies was mapped. The other is transcribed processed pseudogene TPPsig-BASP1, which is located on chromosome 13q flanking the putative locus for Möbius syndrome and might be involved in the regulation of the transcripts encoded by BASP1. Mutation analyses in nineteen patients excluded these genes as being candidates for Möbius syndrome.
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Affiliation(s)
- Abdullah Uzumcu
- Department of Medical Genetics, Istanbul Medical Faculty, Istanbul University, Istanbul, Turkey
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15
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Anitha A, Nakamura K, Yamada K, Suda S, Thanseem I, Tsujii M, Iwayama Y, Hattori E, Toyota T, Miyachi T, Iwata Y, Suzuki K, Matsuzaki H, Kawai M, Sekine Y, Tsuchiya K, Sugihara GI, Ouchi Y, Sugiyama T, Koizumi K, Higashida H, Takei N, Yoshikawa T, Mori N. Genetic analyses of roundabout (ROBO) axon guidance receptors in autism. Am J Med Genet B Neuropsychiatr Genet 2008; 147B:1019-27. [PMID: 18270976 DOI: 10.1002/ajmg.b.30697] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Autism is a pervasive developmental disorder diagnosed in early childhood. Abnormalities of serotonergic neurotransmission have been reported in autism. Serotonin transporter (SERT) modulates serotonin levels, and is a major therapeutic target in autism. Factors that regulate SERT expression might be implicated in the pathophysiology of autism. One candidate SERT regulatory protein is the roundabout axon guidance molecule, ROBO. SerT expression in Drosophila is regulated by robo; it plays a vital role in mammalian neurodevelopment also. Here, we examined the associations of ROBO3 and ROBO4 with autism, in a trio association study using DNA from 252 families recruited to AGRE. Four SNPs of ROBO3 (rs3923890, P = 0.023; rs7925879, P = 0.017; rs4606490, P = 0.033; and rs3802905, P = 0.049) and a single SNP of ROBO4 (rs6590109, P = 0.009) showed associations with autism; the A/A genotype of rs3923890 showed lower ADI-R_A scores, which reflect social interaction. Significant haplotype associations were also observed for ROBO3 and ROBO4. We further compared the mRNA expressions of ROBO1, ROBO2, ROBO3, and ROBO4 in the lymphocytes of 19 drug-naïve autistic patients and 20 age- and sex-matched controls. Expressions of ROBO1 (P = 0.018) and ROBO2 (P = 0.023) were significantly reduced in the autistic group; the possibility of using the altered expressions of ROBO as peripheral markers for autism, may be explored. In conclusion, we suggest a possible role of ROBO in the pathogenesis of autism. Abnormalities of ROBO may lead to autism either by interfering with serotonergic system, or by disrupting neurodevelopment. To the best of our knowledge, this is the first report relating ROBO with autism.
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Affiliation(s)
- A Anitha
- Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, Hamamatsu, Japan
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16
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Olfactomedin-2 mediates development of the anterior central nervous system and head structures in zebrafish. Mech Dev 2007; 125:167-81. [PMID: 18037275 DOI: 10.1016/j.mod.2007.09.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 09/06/2007] [Accepted: 09/13/2007] [Indexed: 11/24/2022]
Abstract
Olfactomedins comprise a diverse family of secreted glycoproteins, which includes noelin, tiarin, pancortin and gliomedin, implicated in development of the nervous system, and the glaucoma-associated protein myocilin. Here we show in zebrafish that olfactomedin-2 (OM2) is a developmentally regulated gene, and that knockdown of protein expression by morpholino antisense oligonucleotides leads to perturbations of nervous system development. Interference with OM2 expression results in impaired development of branchiomotor neurons, specific disruption of the late phase branchiomotor axon guidance, and affects development of the caudal pharyngeal arches, olfactory pits, eyes and optic tectum. Effects of OM2 knockdown on eye development are likely associated with Pax6 signaling in developing eyes, as Pax6.1 and Pax6.2 mRNA expression patterns are altered in the eyes of OM2 morphants. The specific absence of most cartilaginous structures in the pharyngeal arches indicates that the observed craniofacial phenotypes may be due to perturbed differentiation of cranial neural crest cells. Our studies show that this member of the olfactomedin protein family is an important regulator of development of the anterior nervous system.
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17
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Longo-Guess CM, Gagnon LH, Fritzsch B, Johnson KR. Targeted knockout and lacZ reporter expression of the mouse Tmhs deafness gene and characterization of the hscy-2J mutation. Mamm Genome 2007; 18:646-56. [PMID: 17876667 PMCID: PMC2613174 DOI: 10.1007/s00335-007-9049-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 06/14/2007] [Indexed: 01/03/2023]
Abstract
The Tmhs gene codes for a tetraspan transmembrane protein that is expressed in hair cell stereocilia. We previously showed that a spontaneous missense mutation of Tmhs underlies deafness and vestibular dysfunction in the hurry-scurry (hscy) mouse. Subsequently, mutations in the human TMHS gene were shown to be responsible for DFNB67, an autosomal recessive nonsyndromic deafness locus. Here we describe a genetically engineered null mutation of the mouse Tmhs gene (Tmhs ( tm1Kjn )) and show that its phenotype is identical to that of the hscy missense mutation, confirming the deleterious nature of the hscy cysteine-to-phenylalanine substitution. In the targeted null allele, the Tmhs promoter drives expression of a lacZ reporter gene. Visualization of beta-galactosidase activity in Tmhs ( tm1Kjn ) heterozygous mice indicates that Tmhs is highly expressed in the cochlear and vestibular hair cells of the inner ear. Expression is first detectable at E15.5, peaks around P0, decreases slightly at P6, and is absent by P15, a duration that supports the involvement of Tmhs in stereocilia development. Tmhs reporter gene expression also was detected in several cranial and cervical sensory ganglia, but not in the vestibular or spiral ganglia. We also describe a new nontargeted mutation of the Tmhs gene, hscy-2J, that causes abnormal splicing from a cryptic splice site within exon 2 and is predicted to produce a functionally null protein lacking 51 amino acids of the wild-type sequence.
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18
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Fontán-Gabás L, Oliemuller E, Martínez-Irujo JJ, de Miguel C, Rouzaut A. All-trans-retinoic acid inhibits collapsin response mediator protein-2 transcriptional activity during SH-SY5Y neuroblastoma cell differentiation. FEBS J 2006; 274:498-511. [PMID: 17229153 DOI: 10.1111/j.1742-4658.2006.05597.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neurons are highly polarized cells composed of two structurally and functionally distinct parts, the axon and the dendrite. The establishment of this asymmetric structure is a tightly regulated process. In fact, alterations in the proteins involved in the configuration of the microtubule lattice are frequent in neuro-oncologic diseases. One of these cytoplasmic mediators is the protein known as collapsin response mediator protein-2, which interacts with and promotes tubulin polymerization. In this study, we investigated collapsin response mediator protein-2 transcriptional regulation during all-trans-retinoic acid-induced differentiation of SH-SY5Y neuroblastoma cells. All-trans-retinoic acid is considered to be a potential preventive and therapeutic agent, and has been extensively used to differentiate neuroblastoma cells in vitro. Therefore, we first demonstrated that collapsin response mediator protein-2 mRNA levels are downregulated during the differentiation process. After completion of deletion construct analysis and mutagenesis and mobility shift assays, we concluded that collapsin response mediator protein-2 basal promoter activity is regulated by the transcription factors AP-2 and Pax-3, whereas E2F, Sp1 and NeuroD1 seem not to participate in its regulation. Furthermore, we finally established that reduced expression of collapsin response mediator protein-2 after all-trans-retinoic acid exposure is associated with impaired Pax-3 and AP-2 binding to their consensus sequences in the collapsin response mediator protein-2 promoter. Decreased attachment of AP-2 is a consequence of its accumulation in the cytoplasm. On the other hand, Pax-3 shows lower binding due to all-trans-retinoic acid-mediated transcriptional repression. Unraveling the molecular mechanisms behind the action of all-trans-retinoic acid on neuroblastoma cells may well offer new perspectives for its clinical application.
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19
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Caspary T, Anderson KV. Uncovering the uncharacterized and unexpected: unbiased phenotype-driven screens in the mouse. Dev Dyn 2006; 235:2412-23. [PMID: 16724327 DOI: 10.1002/dvdy.20853] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Phenotype-based chemical mutagenesis screens for mouse mutations have undergone a transformation in the past five years from a potential approach to a practical tool. This change has been driven by the relative ease of identifying causative mutations now that the complete genome sequence is available. These unbiased screens make it possible to identify genes, gene functions and processes that are uniquely important to mammals. In addition, because chemical mutagenesis generally induces point mutations, these alleles often uncover previously unappreciated functions of known proteins. Here we provide examples of the success stories from forward genetic screens, emphasizing the examples that illustrate the discovery of mammalian-specific processes that could not be discovered in other model organisms. As the efficiency of sequencing and mutation detection continues to improve, it is likely that forward genetic screens will provide an even more important part of the repertoire of mouse genetics in the future.
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Affiliation(s)
- Tamara Caspary
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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