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Atac D, Maggi K, Feil S, Maggi J, Cuevas E, Sowden JC, Koller S, Berger W. Identification and Characterization of ATOH7-Regulated Target Genes and Pathways in Human Neuroretinal Development. Cells 2024; 13:1142. [PMID: 38994994 PMCID: PMC11240604 DOI: 10.3390/cells13131142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 06/27/2024] [Accepted: 06/29/2024] [Indexed: 07/13/2024] Open
Abstract
The proneural transcription factor atonal basic helix-loop-helix transcription factor 7 (ATOH7) is expressed in early progenitors in the developing neuroretina. In vertebrates, this is crucial for the development of retinal ganglion cells (RGCs), as mutant animals show an almost complete absence of RGCs, underdeveloped optic nerves, and aberrations in retinal vessel development. Human mutations are rare and result in autosomal recessive optic nerve hypoplasia (ONH) or severe vascular changes, diagnosed as autosomal recessive persistent hyperplasia of the primary vitreous (PHPVAR). To better understand the role of ATOH7 in neuroretinal development, we created ATOH7 knockout and eGFP-expressing ATOH7 reporter human induced pluripotent stem cells (hiPSCs), which were differentiated into early-stage retinal organoids. Target loci regulated by ATOH7 were identified by Cleavage Under Targets and Release Using Nuclease with sequencing (CUT&RUN-seq) and differential expression by RNA sequencing (RNA-seq) of wildtype and mutant organoid-derived reporter cells. Additionally, single-cell RNA sequencing (scRNA-seq) was performed on whole organoids to identify cell type-specific genes. Mutant organoids displayed substantial deficiency in axon sprouting, reduction in RGCs, and an increase in other cell types. We identified 469 differentially expressed target genes, with an overrepresentation of genes belonging to axon development/guidance and Notch signaling. Taken together, we consolidate the function of human ATOH7 in guiding progenitor competence by inducing RGC-specific genes while inhibiting other cell fates. Furthermore, we highlight candidate genes responsible for ATOH7-associated optic nerve and retinovascular anomalies, which sheds light to potential future therapy targets for related disorders.
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Affiliation(s)
- David Atac
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Kevin Maggi
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Silke Feil
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Jordi Maggi
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Elisa Cuevas
- UCL Great Ormond Street Institute of Child Health, University College London and NIHR Great Ormond Street Hospital Biomedical Research Centre, London WC1N 1EH, UK
| | - Jane C Sowden
- UCL Great Ormond Street Institute of Child Health, University College London and NIHR Great Ormond Street Hospital Biomedical Research Centre, London WC1N 1EH, UK
| | - Samuel Koller
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Wolfgang Berger
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, 8057 Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
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2
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Moon S, Lee HH, Archer-Hartmann S, Nagai N, Mubasher Z, Parappurath M, Ahmed L, Ramos RL, Kimata K, Azadi P, Cai W, Zhao JY. Knockout of the intellectual disability-linked gene Hs6st2 in mice decreases heparan sulfate 6-O-sulfation, impairs dendritic spines of hippocampal neurons, and affects memory. Glycobiology 2024; 34:cwad095. [PMID: 38015989 PMCID: PMC10969535 DOI: 10.1093/glycob/cwad095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023] Open
Abstract
Heparan sulfate (HS) is a linear polysaccharide that plays a key role in cellular signaling networks. HS functions are regulated by its 6-O-sulfation, which is catalyzed by three HS 6-O-sulfotransferases (HS6STs). Notably, HS6ST2 is mainly expressed in the brain and HS6ST2 mutations are linked to brain disorders, but the underlying mechanisms remain poorly understood. To determine the role of Hs6st2 in the brain, we carried out a series of molecular and behavioral assessments on Hs6st2 knockout mice. We first carried out strong anion exchange-high performance liquid chromatography and found that knockout of Hs6st2 moderately decreases HS 6-O-sulfation levels in the brain. We then assessed body weights and found that Hs6st2 knockout mice exhibit increased body weight, which is associated with abnormal metabolic pathways. We also performed behavioral tests and found that Hs6st2 knockout mice showed memory deficits, which recapitulate patient clinical symptoms. To determine the molecular mechanisms underlying the memory deficits, we used RNA sequencing to examine transcriptomes in two memory-related brain regions, the hippocampus and cerebral cortex. We found that knockout of Hs6st2 impairs transcriptome in the hippocampus, but only mildly in the cerebral cortex. Furthermore, the transcriptome changes in the hippocampus are enriched in dendrite and synapse pathways. We also found that knockout of Hs6st2 decreases HS levels and impairs dendritic spines in hippocampal CA1 pyramidal neurons. Taken together, our study provides novel molecular and behavioral insights into the role of Hs6st2 in the brain, which facilitates a better understanding of HS6ST2 and HS-linked brain disorders.
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Affiliation(s)
- Sohyun Moon
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Hiu Ham Lee
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Stephanie Archer-Hartmann
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States
| | - Naoko Nagai
- Institute for Molecular Science of Medicine, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan
| | - Zainab Mubasher
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Mahima Parappurath
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Laiba Ahmed
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Raddy L Ramos
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Koji Kimata
- Multidisciplinary Pain Center, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, United States
| | - Weikang Cai
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
| | - Jerry Yingtao Zhao
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, New York 11568, United States
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3
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Yamamoto T, Kaneshima T, Tsukano K, Michiue T. The heparan sulfate modification enzyme, Hs6st1, governs Xenopus neuroectodermal patterning by regulating distributions of Fgf and Noggin. Dev Biol 2023; 496:87-94. [PMID: 36739958 DOI: 10.1016/j.ydbio.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 01/20/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023]
Abstract
The nervous system has various types of cells derived from three neuroectodermal regions: neural plate (NP), neural crest (NC), and preplacodal ectoderm (PPE). Differentiation of these regions is regulated by various morphogens. However, regulatory mechanisms of morphogen distribution in neural patterning are still debated. In general, an extracellular component, heparan sulfate (HS), is essential to regulate morphogen gradients by modulating morphogen binding. The present study focused on an HS modification enzyme, heparan sulfate 6-O-sulfotransferase 1 (Hs6st1), which is highly expressed during the neurula stage in Xenopus. Our present in situ hybridization analysis revealed that Hs6st1 is expressed in the lateral sensorial layer of neuroectoderm. Overexpression of Hs6st1 expands Sox3 (NP marker gene) expression, and slightly dampens FoxD3 (NC marker) expression. Hs6st1 knockout using the CRISPR/Cas9 system also expands the neural plate region, followed by retinal malformation. These results imply that 6-O sulfation, mediated by Hs6st1, selectively regulates morphogen distribution required for neuroectodermal patterning. Among morphogens required for patterning, Fgf8a accumulates on Hs6st1-expressing cells, whereas a secreted BMP antagonist, Noggin, diffuses away from those cells. Thus, cell-autonomous 6-O sulfation of HS at the sensorial layer of neuroectoderm also affects neuroectodermal patterning in neighboring regions, including neural plate and neural crest, not only through accumulation, but also through dispersal of specific morphogens.
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Affiliation(s)
- Takayoshi Yamamoto
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
| | - Toki Kaneshima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Kohei Tsukano
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Tatsuo Michiue
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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4
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Abstract
Establishment of neural circuits requires reproducible and precise interactions between growing axons, dendrites and their tissue environment. Cell adhesion molecules and guidance factors are involved in the process, but how specificity is achieved remains poorly understood. Glycans are the third major class of biopolymers besides nucleic acids and proteins, and are usually covalently linked to proteins to form glycoconjugates. Common to most glycans is an extraordinary level of molecular diversity, making them attractive candidates to contribute specificity during neural development. Indeed, many genes important for neural development encode glycoproteins, or enzymes involved in synthesizing or modifying glycans. Glycoconjugates are classified based on both the types of glycans and type of attachment that link them to proteins. Here I discuss progress in understanding the function of glycans, glycan modifications and glycoconjugates during neural development in Caenorhabditis elegans. I will also highlight relevance to human disease and known roles of glycoconjugates in regeneration.
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Affiliation(s)
- Hannes E Bülow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, United States; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, United States.
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5
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Townley RA, Bülow HE. Deciphering functional glycosaminoglycan motifs in development. Curr Opin Struct Biol 2018; 50:144-154. [PMID: 29579579 PMCID: PMC6078790 DOI: 10.1016/j.sbi.2018.03.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 01/12/2023]
Abstract
Glycosaminoglycans (GAGs) such as heparan sulfate, chondroitin/dermatan sulfate, and keratan sulfate are linear glycans, which when attached to protein backbones form proteoglycans. GAGs are essential components of the extracellular space in metazoans. Extensive modifications of the glycans such as sulfation, deacetylation and epimerization create structural GAG motifs. These motifs regulate protein-protein interactions and are thereby repsonsible for many of the essential functions of GAGs. This review focusses on recent genetic approaches to characterize GAG motifs and their function in defined signaling pathways during development. We discuss a coding approach for GAGs that would enable computational analyses of GAG sequences such as alignments and the computation of position weight matrices to describe GAG motifs.
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Affiliation(s)
- Robert A Townley
- Department of Biological Sciences, Columbia University, New York, NY 10027, United States
| | - Hannes E Bülow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, United States; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
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6
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Yu P, Pearson CS, Geller HM. Flexible Roles for Proteoglycan Sulfation and Receptor Signaling. Trends Neurosci 2018; 41:47-61. [PMID: 29150096 PMCID: PMC5748001 DOI: 10.1016/j.tins.2017.10.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/19/2017] [Accepted: 10/25/2017] [Indexed: 11/25/2022]
Abstract
Proteoglycans (PGs) in the extracellular matrix (ECM) play vital roles in axon growth and navigation, plasticity, and regeneration of injured neurons. Different classes of PGs may support or inhibit cell growth, and their functions are determined in part by highly specific structural features. Among these, the pattern of sulfation on the PG sugar chains is a paramount determinant of a diverse and flexible set of outcomes. Recent studies of PG sulfation illustrate the challenges of attributing biological actions to specific sulfation patterns, and suggest ways in which highly similar molecules may exert opposing effects on neurons. The receptors for PGs, which have yet to be fully characterized, display a similarly nuanced spectrum of effects. Different classes of PG function via overlapping families of receptors and signaling pathways. This enables them to control axon growth and guidance with remarkable specificity, but it poses challenges for determining the precise binding interactions and downstream effects of different PGs and their assorted sulfated epitopes. This review examines existing and emerging evidence for the roles of PG sulfation and receptor interactions in determining how these complex molecules influence neuronal development, growth, and function.
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Affiliation(s)
- Panpan Yu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration; Ministry of Education Joint International Research Laboratory of CNS Regeneration, Jinan University, Guangzhou 510632, China.
| | - Craig S Pearson
- Laboratory of Developmental Neurobiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA; Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Herbert M Geller
- Laboratory of Developmental Neurobiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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7
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Gezelius H, Moreno-Juan V, Mezzera C, Thakurela S, Rodríguez-Malmierca LM, Pistolic J, Benes V, Tiwari VK, López-Bendito G. Genetic Labeling of Nuclei-Specific Thalamocortical Neurons Reveals Putative Sensory-Modality Specific Genes. Cereb Cortex 2017; 27:5054-5069. [PMID: 27655933 PMCID: PMC7610997 DOI: 10.1093/cercor/bhw290] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 08/22/2016] [Indexed: 11/14/2022] Open
Abstract
The thalamus is a central brain structure with topographically ordered long-range axonal projections that convey sensory information to the cortex via distinct nuclei. Although there is an increasing knowledge about genes important for thalamocortical (TC) development, the identification of genetic landmarks of the distinct thalamic nuclei during the embryonic development has not been addressed systematically. Indeed, a more comprehensive understanding of how the axons from the individual nuclei find their way and connect to their corresponding cortical area is called for. Here, we used a genetic dual labeling strategy in mice to purify distinct principal sensory thalamic neurons. Subsequent genome-wide transcriptome profiling revealed genes specifically expressed in each nucleus during embryonic development. Analysis of regulatory regions of the identified genes revealed key transcription factors and networks that likely underlie the specification of individual sensory-modality TC connections. Finally, the importance of correct axon targeting for the specific sensory-modality population transcriptome was evidenced in a Sema6A mutant, in which visual TC axons are derailed at embryonic life. In sum, our data determined the developmental transcriptional profile of the TC neurons that will eventually support sensory processing.
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Affiliation(s)
- Henrik Gezelius
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, 03550, Spain
| | - Verónica Moreno-Juan
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, 03550, Spain
| | - Cecilia Mezzera
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, 03550, Spain
- Present address: Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
| | - Sudhir Thakurela
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128 Mainz, Germany
| | - Luis Miguel Rodríguez-Malmierca
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, 03550, Spain
| | | | - Vladimir Benes
- EMBL, GeneCore, Meyerhofstr. 1, D-69117 Heidelberg, Germany
| | - Vijay K. Tiwari
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128 Mainz, Germany
| | - Guillermina López-Bendito
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, 03550, Spain
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8
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Saied-Santiago K, Townley RA, Attonito JD, da Cunha DS, Díaz-Balzac CA, Tecle E, Bülow HE. Coordination of Heparan Sulfate Proteoglycans with Wnt Signaling To Control Cellular Migrations and Positioning in Caenorhabditis elegans. Genetics 2017; 206:1951-1967. [PMID: 28576860 PMCID: PMC5560800 DOI: 10.1534/genetics.116.198739] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 05/20/2017] [Indexed: 11/18/2022] Open
Abstract
Heparan sulfates (HS) are linear polysaccharides with complex modification patterns, which are covalently bound via conserved attachment sites to core proteins to form heparan sulfate proteoglycans (HSPGs). HSPGs regulate many aspects of the development and function of the nervous system, including cell migration, morphology, and network connectivity. HSPGs function as cofactors for multiple signaling pathways, including the Wnt-signaling molecules and their Frizzled receptors. To investigate the functional interactions among the HSPG and Wnt networks, we conducted genetic analyses of each, and also between these networks using five cellular migrations in the nematode Caenorhabditis elegans We find that HSPG core proteins act genetically in a combinatorial fashion dependent on the cellular contexts. Double mutant analyses reveal distinct redundancies among HSPGs for different migration events, and different cellular migrations require distinct heparan sulfate modification patterns. Our studies reveal that the transmembrane HSPG SDN-1/Syndecan functions within the migrating cell to promote cellular migrations, while the GPI-linked LON-2/Glypican functions cell nonautonomously to establish the final cellular position. Genetic analyses with the Wnt-signaling system show that (1) a given HSPG can act with different Wnts and Frizzled receptors, and that (2) a given Wnt/Frizzled pair acts with different HSPGs in a context-dependent manner. Lastly, we find that distinct HSPG and Wnt/Frizzled combinations serve separate functions to promote cellular migration and establish position of specific neurons. Our studies suggest that HSPGs use structurally diverse glycans in coordination with Wnt-signaling pathways to control multiple cellular behaviors, including cellular and axonal migrations and, cellular positioning.
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Affiliation(s)
| | - Robert A Townley
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - John D Attonito
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Dayse S da Cunha
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Carlos A Díaz-Balzac
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Eillen Tecle
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Hannes E Bülow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
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9
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Attreed M, Saied-Santiago K, Bülow HE. Conservation of anatomically restricted glycosaminoglycan structures in divergent nematode species. Glycobiology 2016; 26:862-870. [PMID: 26976619 PMCID: PMC5018047 DOI: 10.1093/glycob/cww037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/04/2016] [Accepted: 03/08/2016] [Indexed: 11/14/2022] Open
Abstract
Heparan sulfates (HS) are glycosaminoglycans of the extracellular matrices and characterized by complex modification patterns owing to sulfations, epimerization, and acetylation. Distinct HS modification patterns have been shown to modulate protein-protein interactions during development in general and of the nervous system in particular. This has led to the heparan sulfate code hypothesis, which posits that specifically modified HS epitopes are distributed in a tissue and cell-specific fashion to orchestrate neural circuit formation. Whether an HS code exists in vivo, how specific or how evolutionarily conserved the anatomical distribution of an HS code may be has remained unknown. Here we conduct a systematic comparison of HS modification patterns in the nematode Caenorhabditis elegans using transgenic expression of 33 different HS-specific single chain variable fragment antibodies. We find that some HS modification patterns are widely distributed in the nervous system. In contrast, other HS modification patterns appear highly cell-specific in both non-neuronal and neuronal cells. Some patterns can be as restricted in their localization as to single neurites or synaptic connections between two neurons. This restricted anatomical localization of specific HS patterns can be evolutionarily conserved over a span of 80-100 million years in the divergent nematode species Caenorhabditis briggsae suggesting structural and, possibly functional conservation of glycosaminoglycan structures similar to proteins. These findings suggest a HS code with subcellularly localized, unique glycan identities in the nervous system.
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Affiliation(s)
| | | | - Hannes E Bülow
- Department of Genetics
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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10
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Stanley P. What Have We Learned from Glycosyltransferase Knockouts in Mice? J Mol Biol 2016; 428:3166-3182. [PMID: 27040397 DOI: 10.1016/j.jmb.2016.03.025] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 11/16/2022]
Abstract
There are five major classes of glycan including N- and O-glycans, glycosaminoglycans, glycosphingolipids, and glycophosphatidylinositol anchors, all expressed at the molecular frontier of each mammalian cell. Numerous biological consequences of altering the expression of mammalian glycans are understood at a mechanistic level, but many more remain to be characterized. Mouse mutants with deleted, defective, or misexpressed genes that encode activities necessary for glycosylation have led the way to identifying key functions of glycans in biology. However, with the advent of exome sequencing, humans with mutations in genes involved in glycosylation are also revealing specific requirements for glycans in mammalian development. The aim of this review is to summarize glycosylation genes that are necessary for mouse embryonic development, pathway-specific glycosylation genes whose deletion leads to postnatal morbidity, and glycosylation genes for which effects are mild, but perturbation of the organism may reveal functional consequences. General strategies for generating and interpreting the phenotype of mice with glycosylation defects are discussed in relation to human congenital disorders of glycosylation (CDG).
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Affiliation(s)
- Pamela Stanley
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461, USA.
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11
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Abstract
Heparan sulfate proteoglycans (HSPGs) have long been implicated in a wide range of cell-cell signaling and cell-matrix interactions, both in vitro and in vivo in invertebrate models. Although many of the genes that encode HSPG core proteins and the biosynthetic enzymes that generate and modify HSPG sugar chains have not yet been analyzed by genetics in vertebrates, recent studies have shown that HSPGs do indeed mediate a wide range of functions in early vertebrate development, for example during left-right patterning and in cardiovascular and neural development. Here, we provide a comprehensive overview of the various roles of HSPGs in these systems and explore the concept of an instructive heparan sulfate sugar code for modulating vertebrate development. Summary: This Review article examines the role of heparan sulfate proteoglycans in vertebrate development and explores the concept of an instructive 'sugar code' for modulating development.
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Affiliation(s)
- Fabienne E Poulain
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - H Joseph Yost
- University of Utah, Department of Neurobiology and Anatomy, Department of Pediatrics, Salt Lake City, UT 84132, USA
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12
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Mizumoto S, Yamada S, Sugahara K. Human genetic disorders and knockout mice deficient in glycosaminoglycan. BIOMED RESEARCH INTERNATIONAL 2014; 2014:495764. [PMID: 25126564 PMCID: PMC4122003 DOI: 10.1155/2014/495764] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/08/2014] [Indexed: 12/20/2022]
Abstract
Glycosaminoglycans (GAGs) are constructed through the stepwise addition of respective monosaccharides by various glycosyltransferases and maturated by epimerases and sulfotransferases. The structural diversity of GAG polysaccharides, including their sulfation patterns and sequential arrangements, is essential for a wide range of biological activities such as cell signaling, cell proliferation, tissue morphogenesis, and interactions with various growth factors. Studies using knockout mice of enzymes responsible for the biosynthesis of the GAG side chains of proteoglycans have revealed their physiological functions. Furthermore, mutations in the human genes encoding glycosyltransferases, sulfotransferases, and related enzymes responsible for the biosynthesis of GAGs cause a number of genetic disorders including chondrodysplasia, spondyloepiphyseal dysplasia, and Ehlers-Danlos syndromes. This review focused on the increasing number of glycobiological studies on knockout mice and genetic diseases caused by disturbances in the biosynthetic enzymes for GAGs.
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Affiliation(s)
- Shuji Mizumoto
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan
| | - Shuhei Yamada
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan
| | - Kazuyuki Sugahara
- Laboratory of Proteoglycan Signaling and Therapeutics, Frontier Research Center for Post-Genomic Science and Technology, Graduate School of Life Science, Hokkaido University, West-11, North-21, Kita-ku, Sapporo, Hokkaido 001-0021, Japan
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13
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Heparan sulfotransferases Hs6st1 and Hs2st keep Erk in check for mouse corpus callosum development. J Neurosci 2014; 34:2389-401. [PMID: 24501377 DOI: 10.1523/jneurosci.3157-13.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The corpus callosum (CC) connects the left and right cerebral hemispheres in mammals and its development requires intercellular communication at the telencephalic midline mediated by signaling proteins. Heparan sulfate (HS) is a sulfated polysaccharide that decorates cell surface and extracellular matrix proteins and regulates the biological activity of numerous signaling proteins via sugar-protein interactions. HS is subject to regulated enzymatic sulfation and desulfation and an attractive, although not proven, hypothesis is that the biological activity of HS is regulated by a sugar sulfate code. Mutant mouse embryos lacking the heparan sulfotransferases Hs2st or Hs6st1 have severe CC phenotypes and form Probst bundles of noncrossing axons flanking large tangles of midline glial processes. Here, we identify a precocious accumulation of Sox9-expressing glial cells in the indusium griseum region and a corresponding depletion at the glial wedge associated with the formation of Probst bundles along the rostrocaudal axis in both mutants. Molecularly, we found a surprising hyperactivation of Erk signaling in Hs2st(-/-) (2-fold) and Hs6st1(-/-) (6-fold) embryonic telencephalon that was most striking at the midline, where Erk signaling is lowest in wild-types, and a 2-fold increase in Fgf8 protein levels in Hs6st1(-/-) embryos that could underpin Erk hyperactivation and excessive glial movement to the indusium griseum. The tightly linked Hs6st1(-/-) CC glial and axonal phenotypes can be rescued by genetic or pharmacological suppression of Fgf8/Erk axis components. Overall, our data fit a model in which Hs2st and Hs6st1 normally generate conditions conducive to CC development by generating an HS-containing environment that keeps Erk signaling in check.
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Price DJ, Clegg J, Duocastella XO, Willshaw D, Pratt T. The importance of combinatorial gene expression in early Mammalian thalamic patterning and thalamocortical axonal guidance. Front Neurosci 2012; 6:37. [PMID: 22435047 PMCID: PMC3304307 DOI: 10.3389/fnins.2012.00037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/28/2012] [Indexed: 12/24/2022] Open
Abstract
The thalamus is essential for sensory perception. In mammals, work on the mouse has taught us most of what we know about how it develops and connects to the cortex. The mature thalamus of all mammalian species comprises numerous anatomically distinct collections of neurons called nuclei that differ in function, connectivity, and molecular constitution. At the time of its initial appearance as a distinct structure following neural tube closure, the thalamus is already patterned by the regional expression of numerous regulatory genes. This patterning, which lays down the blueprint for later development of thalamic nuclei, predates the development of thalamocortical projections. In this review we apply novel analytical methods to gene expression data available in the Allen Developing Mouse Brain Atlas to highlight the complex organized molecular heterogeneity already present among cells in the thalamus from the earliest stages at which it contains differentiating neurons. This early patterning is likely to invest in axons growing from different parts of the thalamus the ability to navigate in an ordered way to their appropriate area in the cerebral cortex. We review the mechanisms and cues that thalamic axons use, encounter, and interpret to attain the cortex. Mechanisms include guidance by previously generated guidepost cells, such as those in the subpallium that maintain thalamic axonal order and direction, and axons such as those of reciprocal projections from intermediate structures or from the cortex itself back toward the thalamus. We show how thalamocortical pathfinding involves numerous guidance cues operating at a series of steps along their route. We stress the importance of the combinatorial actions of multiple genes for the development of the numerous specific identities and functions of cells in this exquisitely complex system and their orderly innervation of the cortex.
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Affiliation(s)
- David J Price
- Centre for Integrative Physiology, University of Edinburgh Edinburgh, UK
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