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Cazares O, Chen M, Menendez J, Molinuevo R, Thomas G, Cervantes J, Yee M, Cadell M, Durham M, Zhu Y, Strietzel C, Bubolz JW, Hinck L. SLIT Loss or Sequestration Increases Mammary Alveologenesis and Lactogenesis. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001264. [PMID: 39381643 PMCID: PMC11461027 DOI: 10.17912/micropub.biology.001264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 07/17/2024] [Accepted: 09/04/2024] [Indexed: 10/10/2024]
Abstract
SLITs comprise a family of secreted proteins that function as ligands for Roundabout (ROBO) receptors. Previous research showed that ROBO1 promotes the differentiation of milk-producing alveolar cells by inhibiting Notch signaling in mammary luminal cells. Here, we show enhanced alveolar development and increased milk production in Slit2-/-;Slit3-/- knockout mammary gland epithelia. This result can also be achieved by intraperitoneal delivery of recombinant ROBO1 extracellular domain fragment, ROBO1-5Ig-Fc, which sequesters SLITs. Together, our phenotypic studies suggest that SLITs restrict alveologenesis and lactogenesis by inhibiting ROBO1.
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Affiliation(s)
| | - Min Chen
- University of California, Santa Cruz, CA, USA
| | | | | | - Gwen Thomas
- University of California, Santa Cruz, CA, USA
| | | | - Michael Yee
- University of California, Santa Cruz, CA, USA
| | | | | | - Yaqi Zhu
- Zoetis (United States), Kalamazoo, MI, United States
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2
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Curran BM, Nickerson KR, Yung AR, Goodrich LV, Jaworski A, Tessier-Lavigne M, Ma L. Multiple guidance mechanisms control axon growth to generate precise T-shaped bifurcation during dorsal funiculus development in the spinal cord. eLife 2024; 13:RP94109. [PMID: 39159057 PMCID: PMC11333043 DOI: 10.7554/elife.94109] [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: 08/21/2024] Open
Abstract
The dorsal funiculus in the spinal cord relays somatosensory information to the brain. It is made of T-shaped bifurcation of dorsal root ganglion (DRG) sensory axons. Our previous study has shown that Slit signaling is required for proper guidance during bifurcation, but loss of Slit does not affect all DRG axons. Here, we examined the role of the extracellular molecule Netrin-1 (Ntn1). Using wholemount staining with tissue clearing, we showed that mice lacking Ntn1 had axons escaping from the dorsal funiculus at the time of bifurcation. Genetic labeling confirmed that these misprojecting axons come from DRG neurons. Single axon analysis showed that loss of Ntn1 did not affect bifurcation but rather altered turning angles. To distinguish their guidance functions, we examined mice with triple deletion of Ntn1, Slit1, and Slit2 and found a completely disorganized dorsal funiculus. Comparing mice with different genotypes using immunolabeling and single axon tracing revealed additive guidance errors, demonstrating the independent roles of Ntn1 and Slit. Moreover, the same defects were observed in embryos lacking their cognate receptors. These in vivo studies thus demonstrate the presence of multi-factorial guidance mechanisms that ensure proper formation of a common branched axonal structure during spinal cord development.
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Affiliation(s)
- Bridget M Curran
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber, Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson UniversityPhiladelphiaUnited States
| | - Kelsey R Nickerson
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Robert J. and Nancy D. Carney Institute for Brain ScienceProvidenceUnited States
| | - Andrea R Yung
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Lisa V Goodrich
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Alexander Jaworski
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Robert J. and Nancy D. Carney Institute for Brain ScienceProvidenceUnited States
| | | | - Le Ma
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber, Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson UniversityPhiladelphiaUnited States
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3
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Curran BM, Nickerson KR, Yung AR, Goodrich LV, Jaworski A, Tessier-Lavigne M, Ma L. Multiple Guidance Mechanisms Control Axon Growth to Generate Precise T-shaped Bifurcation during Dorsal Funiculus Development in the Spinal Cord. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.17.567638. [PMID: 38014092 PMCID: PMC10680847 DOI: 10.1101/2023.11.17.567638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The dorsal funiculus in the spinal cord relays somatosensory information to the brain. It is made of T-shaped bifurcation of dorsal root ganglion (DRG) sensory axons. Our previous study has shown that Slit signaling is required for proper guidance during bifurcation, but loss of Slit does not affect all DRG axons. Here, we examined the role of the extracellular molecule Netrin-1 (Ntn1). Using wholemount staining with tissue clearing, we showed that mice lacking Ntn1 have axons escaping from the dorsal funiculus at the time of bifurcation. Genetic labeling confirmed that these misprojecting axons come from DRG neurons. Single axon analysis showed that loss of Ntn1 does not affect bifurcation but rather alters turning angles. To distinguish their guidance functions, we examined mice with triple deletion of Ntn1, Slit1, and Slit2 and found a completely disorganized dorsal funiculus. Comparing mice with different genotypes using immunolabeling and single axon tracing revealed additive guidance errors, demonstrating the independent roles of Ntn1 and Slit. Moreover, the same defects were observed in embryos lacking their cognate receptors. These in vivo studies thus demonstrate the presence of multi-factorial guidance mechanisms that ensure proper formation of a common branched axonal structure during spinal cord development.
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Affiliation(s)
- Bridget M Curran
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107
| | - Kelsey R Nickerson
- Department of Neuroscience, Brown University, Providence, RI 02912
- Robert J. and Nancy D. Carney Institute for Brain Science, Providence, RI 02912
| | - Andrea R Yung
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Lisa V Goodrich
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Alexander Jaworski
- Department of Neuroscience, Brown University, Providence, RI 02912
- Robert J. and Nancy D. Carney Institute for Brain Science, Providence, RI 02912
| | | | - Le Ma
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107
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4
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Kerstein PC, Agreda YS, Curran BM, Ma L, Wright KM. Gbx2 controls amacrine cell dendrite stratification through Robo1/2 receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.03.551861. [PMID: 37577554 PMCID: PMC10418232 DOI: 10.1101/2023.08.03.551861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Within the neuronal classes of the retina, amacrine cells (ACs) exhibit the greatest neuronal diversity in morphology and function. We show that the selective expression of the transcription factor Gbx2 is required for cell fate specification and dendritic stratification of an individual AC subtype in the mouse retina. We identify Robo1 and Robo2 as downstream effectors that when deleted, phenocopy the dendritic misprojections seen in Gbx2 mutants. Slit1 and Slit2, the ligands of Robo receptors, are localized to the OFF layers of the inner plexiform layer where we observe the dendritic misprojections in both Gbx2 and Robo1/2 mutants. We show that Robo receptors also are required for the proper dendritic stratification of additional AC subtypes, such as Vglut3+ ACs. These results show both that Gbx2 functions as a terminal selector in a single AC subtype and identify Slit-Robo signaling as a developmental mechanism for ON-OFF pathway segregation in the retina.
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5
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Yallowitz AR, Shim JH, Xu R, Greenblatt MB. An angiogenic approach to osteoanabolic therapy targeting the SHN3-SLIT3 pathway. Bone 2023; 172:116761. [PMID: 37030497 PMCID: PMC10198948 DOI: 10.1016/j.bone.2023.116761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/30/2023] [Accepted: 04/05/2023] [Indexed: 04/10/2023]
Abstract
Often, disorders of impaired bone formation involve not only a cell intrinsic defect in the ability of osteoblasts to form bone, but moreover a broader dysfunction of the skeletal microenvironment that limits osteoblast activity. Developing approaches to osteoanabolic therapy that not only augment osteoblast activity but moreover correct this microenvironmental dysfunction may enable both more effective osteoanabolic therapies and also addressing a broader set of indications where vasculopathy or other forms microenvironment dysfunction feature prominently. We here review evidence that SHN3 acts as a suppressor of not only the cell intrinsic bone formation activity of osteoblasts, but moreover of the creation of a local osteoanabolic microenvironment. Mice lacking Schnurri3 (SHN3, HIVEP3) display a very robust increase in bone formation, that is due to de-repression of ERK pathway signaling in osteoblasts. In addition to loss of SHN3 augmenting the differentiation and bone formation activity of osteoblasts, loss of SHN3 increases secretion of SLIT3 by osteoblasts, which in a skeletal context acts as an angiogenic factor. Through this angiogenic activity, SLIT3 creates an osteoanabolic microenvironment, and accordingly treatment with SLIT3 can increase bone formation and enhance fracture healing. These features both validate vascular endothelial cells as a therapeutic target for disorders of low bone mass alongside the traditionally targeted osteoblasts and osteoclasts and indicate that targeting the SHN3/SLIT3 pathway provides a new mechanism to induce therapeutic osteoanabolic responses.
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Affiliation(s)
- Alisha R Yallowitz
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, United States of America
| | - Jae-Hyuck Shim
- Department of Medicine, Division of Rheumatology, University of Massachusetts Chan Medical School, USA; Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Li Weibo Institute for Rare Diseases Research, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Ren Xu
- The First Affiliated Hospital of Xiamen University-ICMRS Collaborating Center for Skeletal Stem Cells, State Key Laboratory of Cellular Stress Biology, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361005, China; Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Matthew B Greenblatt
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, United States of America; Research Division, Hospital for Special Surgery, New York, NY 10065, United States of America.
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Schneider F, Metz I, Rust MB. Regulation of actin filament assembly and disassembly in growth cone motility and axon guidance. Brain Res Bull 2023; 192:21-35. [PMID: 36336143 DOI: 10.1016/j.brainresbull.2022.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
Directed outgrowth of axons is fundamental for the establishment of neuronal networks. Axon outgrowth is guided by growth cones, highly motile structures enriched in filamentous actin (F-actin) located at the axons' distal tips. Growth cones exploit F-actin-based protrusions to scan the environment for guidance cues, and they contain the sensory apparatus to translate guidance cue information into intracellular signaling cascades. These cascades act upstream of actin-binding proteins (ABP) and thereby control assembly and disassembly of F-actin. Spatiotemporally controlled F-actin dis-/assembly in growth cones steers the axon towards attractants and away from repellents, and it thereby navigates the axon through the developing nervous system. Hence, ABP that control F-actin dynamics emerged as critical regulators of neuronal network formation. In the present review article, we will summarize and discuss current knowledge of the mechanisms that control remodeling of the actin cytoskeleton in growth cones, focusing on recent progress in the field. Further, we will introduce tools and techniques that allow to study actin regulatory mechanism in growth cones.
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Affiliation(s)
- Felix Schneider
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany; Molecular Urooncology, Department of Urology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Isabell Metz
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Marco B Rust
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University Giessen, 35032 Marburg, Germany.
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7
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Schwend T. Wiring the ocular surface: A focus on the comparative anatomy and molecular regulation of sensory innervation of the cornea. Differentiation 2023:S0301-4681(23)00010-5. [PMID: 36997455 DOI: 10.1016/j.diff.2023.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/23/2023] [Indexed: 01/29/2023]
Abstract
The cornea is richly innervated with sensory nerves that function to detect and clear harmful debris from the surface of the eye, promote growth and survival of the corneal epithelium and hasten wound healing following ocular disease or trauma. Given their importance to eye health, the neuroanatomy of the cornea has for many years been a source of intense investigation. Resultantly, complete nerve architecture maps exist for adult human and many animal models and these maps reveal few major differences across species. Interestingly, recent work has revealed considerable variation across species in how sensory nerves are acquired during developmental innervation of the cornea. Highlighting such species-distinct key differences, but also similarities, this review provides a full, comparative anatomy analysis of sensory innervation of the cornea for all species studied to date. Further, this article comprehensively describes the molecules that have been shown to guide and direct nerves toward, into and through developing corneal tissue as the final architectural pattern of the cornea's neuroanatomy is established. Such knowledge is useful for researchers and clinicians seeking to better understand the anatomical and molecular basis of corneal nerve pathologies and to hasten neuro-regeneration following infection, trauma or surgery that damage the ocular surface and its corneal nerves.
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8
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Dhanya SK, Hasan G. Deficits Associated With Loss of STIM1 in Purkinje Neurons Including Motor Coordination Can Be Rescued by Loss of Septin 7. Front Cell Dev Biol 2021; 9:794807. [PMID: 34993201 PMCID: PMC8724567 DOI: 10.3389/fcell.2021.794807] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/15/2021] [Indexed: 12/26/2022] Open
Abstract
Septins are cytoskeletal proteins that can assemble to form heteromeric filamentous complexes and regulate a range of membrane-associated cellular functions. SEPT7, a member of the septin family, functions as a negative regulator of the plasma membrane–localized store-operated Ca2+ entry (SOCE) channel, Orai in Drosophila neurons, and in human neural progenitor cells. Knockdown of STIM, a Ca2+ sensor in the endoplasmic reticulum (ER) and an integral component of SOCE, leads to flight deficits in Drosophila that can be rescued by partial loss of SEPT7 in neurons. Here, we tested the effect of reducing and removing SEPT7 in mouse Purkinje neurons (PNs) with the loss of STIM1. Mice with the complete knockout of STIM1 in PNs exhibit several age-dependent changes. These include altered gene expression in PNs, which correlates with increased synapses between climbing fiber (CF) axons and Purkinje neuron (PN) dendrites and a reduced ability to learn a motor coordination task. Removal of either one or two copies of the SEPT7 gene in STIM1KO PNs restored the expression of a subset of genes, including several in the category of neuron projection development. Importantly, the rescue of gene expression in these animals is accompanied by normal CF-PN innervation and an improved ability to learn a motor coordination task in aging mice. Thus, the loss of SEPT7 in PNs further modulates cerebellar circuit function in STIM1KO animals. Our findings are relevant in the context of identifying SEPT7 as a putative therapeutic target for various neurodegenerative diseases caused by reduced intracellular Ca2+ signaling.
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Affiliation(s)
- Sreeja Kumari Dhanya
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
- SASTRA University, Thanjavur, India
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
- *Correspondence: Gaiti Hasan,
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9
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Maynard TM, Horvath A, Bernot JP, Karpinski BA, Tavares ALP, Shah A, Zheng Q, Spurr L, Olender J, Moody SA, Fraser CM, LaMantia AS, Lee NH. Transcriptional dysregulation in developing trigeminal sensory neurons in the LgDel mouse model of DiGeorge 22q11.2 deletion syndrome. Hum Mol Genet 2021; 29:1002-1017. [PMID: 32047912 PMCID: PMC7158380 DOI: 10.1093/hmg/ddaa024] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 01/12/2020] [Accepted: 02/04/2020] [Indexed: 12/13/2022] Open
Abstract
LgDel mice, which model the heterozygous deletion of genes at human chromosome 22q11.2 associated with DiGeorge/22q11.2 deletion syndrome (22q11DS), have cranial nerve and craniofacial dysfunction as well as disrupted suckling, feeding and swallowing, similar to key 22q11DS phenotypes. Divergent trigeminal nerve (CN V) differentiation and altered trigeminal ganglion (CNgV) cellular composition prefigure these disruptions in LgDel embryos. We therefore asked whether a distinct transcriptional state in a specific population of early differentiating LgDel cranial sensory neurons, those in CNgV, a major source of innervation for appropriate oropharyngeal function, underlies this departure from typical development. LgDel versus wild-type (WT) CNgV transcriptomes differ significantly at E10.5 just after the ganglion has coalesced. Some changes parallel altered proportions of cranial placode versus cranial neural crest-derived CNgV cells. Others are consistent with a shift in anterior-posterior patterning associated with divergent LgDel cranial nerve differentiation. The most robust quantitative distinction, however, is statistically verifiable increased variability of expression levels for most of the over 17 000 genes expressed in common in LgDel versus WT CNgV. Thus, quantitative expression changes of functionally relevant genes and increased stochastic variation across the entire CNgV transcriptome at the onset of CN V differentiation prefigure subsequent disruption of cranial nerve differentiation and oropharyngeal function in LgDel mice.
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Affiliation(s)
- Thomas M Maynard
- Fralin Biomedical Research Institute, Virginia Tech-Carilion School of Medicine, Roanoke, VA, 24016 USA.,Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Anelia Horvath
- Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Pharmacology and Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA.,McCormick Genomics and Proteomics Center, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - James P Bernot
- Department of Pharmacology and Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Beverly A Karpinski
- Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Andre L P Tavares
- Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Ankita Shah
- Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Qianqian Zheng
- Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Liam Spurr
- Department of Pharmacology and Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Jacqueline Olender
- Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Pharmacology and Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Sally A Moody
- Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
| | - Claire M Fraser
- Institute for Genome Sciences, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Anthony-S LaMantia
- Fralin Biomedical Research Institute, Virginia Tech-Carilion School of Medicine, Roanoke, VA, 24016 USA.,Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA.,Department of Biological Sciences, College of Science, Virginia Tech, Blacksburg VA, 24061, USA.,Department of Pediatrics, Virginia Tech Carilion School of Medicine, Roanoke, VA, 24016, USA
| | - Norman H Lee
- Institute for Neuroscience, The George Washington University, Washington, DC 20037, USA.,Department of Pharmacology and Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA
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10
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Yin C, Peterman E, Rasmussen JP, Parrish JZ. Transparent Touch: Insights From Model Systems on Epidermal Control of Somatosensory Innervation. Front Cell Neurosci 2021; 15:680345. [PMID: 34135734 PMCID: PMC8200473 DOI: 10.3389/fncel.2021.680345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 04/28/2021] [Indexed: 12/28/2022] Open
Abstract
Somatosensory neurons (SSNs) densely innervate our largest organ, the skin, and shape our experience of the world, mediating responses to sensory stimuli including touch, pressure, and temperature. Historically, epidermal contributions to somatosensation, including roles in shaping innervation patterns and responses to sensory stimuli, have been understudied. However, recent work demonstrates that epidermal signals dictate patterns of SSN skin innervation through a variety of mechanisms including targeting afferents to the epidermis, providing instructive cues for branching morphogenesis, growth control and structural stability of neurites, and facilitating neurite-neurite interactions. Here, we focus onstudies conducted in worms (Caenorhabditis elegans), fruit flies (Drosophila melanogaster), and zebrafish (Danio rerio): prominent model systems in which anatomical and genetic analyses have defined fundamental principles by which epidermal cells govern SSN development.
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Affiliation(s)
| | | | | | - Jay Z. Parrish
- Department of Biology, University of Washington, Seattle, WA, United States
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11
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Schmidt H, Böttcher A, Gross T, Schmidtko A. cGMP signalling in dorsal root ganglia and the spinal cord: Various functions in development and adulthood. Br J Pharmacol 2021; 179:2361-2377. [PMID: 33939841 DOI: 10.1111/bph.15514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 03/12/2021] [Accepted: 03/31/2021] [Indexed: 12/27/2022] Open
Abstract
Cyclic GMP (cGMP) is a second messenger that regulates numerous physiological and pathophysiological processes. In recent years, more and more studies have uncovered multiple roles of cGMP signalling pathways in the somatosensory system. Accumulating evidence suggests that cGMP regulates different cellular processes from embryonic development through to adulthood. During embryonic development, a cGMP-dependent signalling cascade in the trunk sensory system is essential for axon bifurcation, a specific form of branching of somatosensory axons. In adulthood, various cGMP signalling pathways in distinct cell populations of sensory neurons and dorsal horn neurons in the spinal cord play an important role in the processing of pain and itch. Some of the involved enzymes might serve as a target for future therapies. In this review, we summarise the knowledge regarding cGMP-dependent signalling pathways in dorsal root ganglia and the spinal cord during embryonic development and adulthood, and the potential of targeting these pathways.
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Affiliation(s)
- Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Alexandra Böttcher
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Tilman Gross
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, Frankfurt am Main, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, Frankfurt am Main, Germany
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12
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Purkinje Neurons with Loss of STIM1 Exhibit Age-Dependent Changes in Gene Expression and Synaptic Components. J Neurosci 2021; 41:3777-3798. [PMID: 33737457 DOI: 10.1523/jneurosci.2401-20.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 12/13/2022] Open
Abstract
The stromal interaction molecule 1 (STIM1) is an ER-Ca2+ sensor and an essential component of ER-Ca2+ store operated Ca2+ entry. Loss of STIM1 affects metabotropic glutamate receptor 1 (mGluR1)-mediated synaptic transmission, neuronal Ca2+ homeostasis, and intrinsic plasticity in Purkinje neurons (PNs). Long-term changes of intracellular Ca2+ signaling in PNs led to neurodegenerative conditions, as evident in individuals with mutations of the ER-Ca2+ channel, the inositol 1,4,5-triphosphate receptor. Here, we asked whether changes in such intrinsic neuronal properties, because of loss of STIM1, have an age-dependent impact on PNs. Consequently, we analyzed mRNA expression profiles and cerebellar morphology in PN-specific STIM1 KO mice (STIM1PKO ) of both sexes across ages. Our study identified a requirement for STIM1-mediated Ca2+ signaling in maintaining the expression of genes belonging to key biological networks of synaptic function and neurite development among others. Gene expression changes correlated with altered patterns of dendritic morphology and greater innervation of PN dendrites by climbing fibers, in aging STIM1PKO mice. Together, our data identify STIM1 as an important regulator of Ca2+ homeostasis and neuronal excitability in turn required for maintaining the optimal transcriptional profile of PNs with age. Our findings are significant in the context of understanding how dysregulated calcium signals impact cellular mechanisms in multiple neurodegenerative disorders.SIGNIFICANCE STATEMENT In Purkinje neurons (PNs), the stromal interaction molecule 1 (STIM1) is required for mGluR1-dependent synaptic transmission, refilling of ER Ca2+ stores, regulation of spike frequency, and cerebellar memory consolidation. Here, we provide evidence for a novel role of STIM1 in maintaining the gene expression profile and optimal synaptic connectivity of PNs. Expression of genes related to neurite development and synaptic organization networks is altered in PNs with persistent loss of STIM1. In agreement with these findings the dendritic morphology of PNs and climbing fiber innervations on PNs also undergo significant changes with age. These findings identify a new role for dysregulated intracellular calcium signaling in neurodegenerative disorders and provide novel therapeutic insights.
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13
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Holt E, Stanton-Turcotte D, Iulianella A. Development of the Vertebrate Trunk Sensory System: Origins, Specification, Axon Guidance, and Central Connectivity. Neuroscience 2021; 458:229-243. [PMID: 33460728 DOI: 10.1016/j.neuroscience.2020.12.037] [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: 08/24/2020] [Revised: 12/09/2020] [Accepted: 12/31/2020] [Indexed: 12/26/2022]
Abstract
Crucial to an animal's movement through their environment and to the maintenance of their homeostatic physiology is the integration of sensory information. This is achieved by axons communicating from organs, muscle spindles and skin that connect to the sensory ganglia composing the peripheral nervous system (PNS), enabling organisms to collect an ever-constant flow of sensations and relay it to the spinal cord. The sensory system carries a wide spectrum of sensory modalities - from sharp pain to cool refreshing touch - traveling from the periphery to the spinal cord via the dorsal root ganglia (DRG). This review covers the origins and development of the DRG and the cells that populate it, and focuses on how sensory connectivity to the spinal cord is achieved by the diverse developmental and molecular processes that control axon guidance in the trunk sensory system. We also describe convergences and differences in sensory neuron formation among different vertebrate species to gain insight into underlying developmental mechanisms.
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Affiliation(s)
- Emily Holt
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, and Brain Repair Centre, Life Science Research Institute, 1348 Summer Street, Halifax, Nova Scotia B3H-4R2, Canada
| | - Danielle Stanton-Turcotte
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, and Brain Repair Centre, Life Science Research Institute, 1348 Summer Street, Halifax, Nova Scotia B3H-4R2, Canada
| | - Angelo Iulianella
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, and Brain Repair Centre, Life Science Research Institute, 1348 Summer Street, Halifax, Nova Scotia B3H-4R2, Canada.
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14
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Luo C, Lu Z, Chen Y, Chen X, Liu N, Chen J, Dong S. MicroRNA-640 promotes cell proliferation and adhesion in glioblastoma by targeting Slit guidance ligand 1. Oncol Lett 2020; 21:161. [PMID: 33552279 PMCID: PMC7798089 DOI: 10.3892/ol.2020.12422] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 11/13/2020] [Indexed: 02/06/2023] Open
Abstract
The effects of microRNAs (miRNAs/miRs) on glioblastoma have attracted the attention of researchers in the last 7 years. However, the role of miR-640 and its targeted gene, Slit guidance ligand 1 (SLIT1), in the development of glioblastoma are not yet fully understood. The present study aimed to investigate the role of miR-640 in the proliferation and adhesion of glioblastoma. Reverse transcription-quantitative PCR analysis was performed to detect miR-640 and SLIT1 expression in glioblastoma tissues and cells. In addition, the Dual-luciferase reporter and RNA-pull down assays were performed to assess the association between miR-640 and SLIT1. The Cell Counting Kit-8, BrdU ELISA, cell adhesion and caspase-3 activity assays were also performed to assess cell viability, proliferation, adhesion and apoptosis of glioblastoma cells, respectively. The results demonstrated that miR-640 expression was upregulated in glioblastoma tissues and cells. In addition, miR-640 promoted the cell viability, proliferation and adhesion of glioblastoma cells, while inhibiting cell apoptosis. SLIT1, a direct downstream target of miR-640, was demonstrated to be downregulated in glioblastoma tissues and cells. Furthermore, overexpression of SLIT1 attenuated the promotive effect of miR-640 on glioblastoma cells. Taken together, these results suggest that miR-640 accelerates the proliferation and adhesion of glioblastoma cell lines by targeting and suppressing SLIT1.
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Affiliation(s)
- Chao Luo
- Department of Pediatrics, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430034, P.R. China
| | - Zhiying Lu
- Department of Pediatrics, Kunming Medical University Affiliated Kunming Children's Hospital, Kunming, Yunnan 650034, P.R. China
| | - Yongli Chen
- Department of Pediatrics, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430034, P.R. China
| | - Xiaozhen Chen
- Department of Pediatrics, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430034, P.R. China
| | - Na Liu
- Department of Pediatrics, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430034, P.R. China
| | - Jing Chen
- Department of Pediatrics, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430034, P.R. China
| | - Shanwu Dong
- Department of Pediatrics, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430034, P.R. China
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15
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Kellermeyer R, Heydman LM, Gillis T, Mastick GS, Song M, Kidd T. Proteolytic cleavage of Slit by the Tolkin protease converts an axon repulsion cue to an axon growth cue in vivo. Development 2020; 147:dev.196055. [PMID: 32994163 PMCID: PMC7648596 DOI: 10.1242/dev.196055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/18/2020] [Indexed: 12/27/2022]
Abstract
Slit is a secreted protein that has a canonical function of repelling growing axons from the CNS midline. The full-length Slit (Slit-FL) is cleaved into Slit-N and Slit-C fragments, which have potentially distinct functions via different receptors. Here, we report that the BMP-1/Tolloid family metalloprotease Tolkin (Tok) is responsible for Slit proteolysis in vivo and in vitro. In Drosophilatok mutants lacking Slit cleavage, midline repulsion of axons occurs normally, confirming that Slit-FL is sufficient to repel axons. However, longitudinal axon guidance is highly disrupted in tok mutants and can be rescued by midline expression of Slit-N, suggesting that Slit is the primary substrate for Tok in the embryonic CNS. Transgenic restoration of Slit-N or Slit-C does not repel axons in Slit-null flies. Slit-FL and Slit-N are both biologically active cues with distinct axon guidance functions in vivo Slit signaling is used in diverse biological processes; therefore, differentiating between Slit-FL and Slit fragments will be essential for evaluating Slit function in broader contexts.
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Affiliation(s)
| | | | | | | | | | - Thomas Kidd
- Department of Biology/MS 314, University of Nevada, 1664 North Virginia Street, Reno, NV 89557, USA
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16
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He XF, Li G, Li LL, Li MY, Liang FY, Chen X, Hu XQ. Overexpression of Slit2 decreases neuronal excitotoxicity, accelerates glymphatic clearance, and improves cognition in a multiple microinfarcts model. Mol Brain 2020; 13:135. [PMID: 33028376 PMCID: PMC7542754 DOI: 10.1186/s13041-020-00659-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/21/2020] [Indexed: 01/17/2023] Open
Abstract
Background Cerebral microinfarcts (MIs) lead to progressive cognitive impairments in the elderly, and there is currently no effective preventative strategy due to uncertainty about the underlying pathogenic mechanisms. One possibility is the dysfunction of GABAergic transmission and ensuing excitotoxicity. Dysfunction of GABAergic transmission induces excitotoxicity, which contributes to stroke pathology, but the mechanism has kept unknown. The secreted leucine-rich repeat (LRR) family protein slit homologue 2 (Slit2) upregulates GABAergic activity and protects against global cerebral ischemia, but the neuroprotective efficacy of Slit2 against MIs has not been examined. Methods Middle-aged Wild type (WT) and Slit2-Tg mice were divided into sham and MI treatment groups. MIs were induced in parietal cortex by laser-evoked arteriole occlusion. Spatial memory was then compared between sham and MI groups using the Morris water maze (MWM) task. In addition, neuronal activity, blood brain barrier (BBB) permeability, and glymphatic clearance in peri-infarct areas were compared using two-photon imaging, while GABAergic transmission, microglial activation, neuronal loss, and altered cortical connectivity were compared by immunofluorescent staining or western blotting. Results Microinfarcts increased the amplitude and frequency of spontaneous intracellular Ca2+ signals, reduced neuronal survival and connectivity within parietal cortex, decreased the number of GABAergic interneurons and expression of vesicular GABA transporter (VGAT), induced neuroinflammation, and impaired both glymphatic clearance and spatial memory. Alternatively, Slit2 overexpression attenuated dysfunctional neuronal Ca2+ signaling, protected against neuronal death in the peri-infarct area as well as loss of parietal cortex connectivity, increased GABAergic interneuron number and VGAT expression, attenuated neuroinflammation, and improved both glymphatic clearance and spatial memory. Conclusion Our results strongly suggest that overexpression of Slit2 protected against the dysfunction in MIs, which is a potential therapeutic target for cognition impairment in the elderly.
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Affiliation(s)
- Xiao-Fei He
- Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, 600 Tianhe Road, Guangzhou, Guangdong, China
| | - Ge Li
- Guangdong Provincial Key Laboratory of Laboratory Animals, Guangdong Laboratory Animals Monitoring Institute, Guangzhou, 510663, Guangdong, China
| | - Li-Li Li
- Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, 600 Tianhe Road, Guangzhou, Guangdong, China
| | - Ming-Yue Li
- Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, 600 Tianhe Road, Guangzhou, Guangdong, China
| | - Feng-Yin Liang
- Department of Neurology, National Key clinical department and Key discipline of Neurology, Guangdong Key Laboratory for diagnosis and Treatment of Major Neurological diseases, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, China
| | - Xi Chen
- Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, 600 Tianhe Road, Guangzhou, Guangdong, China.
| | - Xi-Quan Hu
- Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, 600 Tianhe Road, Guangzhou, Guangdong, China.
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17
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Ferrero Restelli F, Fontanet PA, De Vincenti AP, Falzone TL, Ledda F, Paratcha G. Tetraspanin1 promotes NGF signaling by controlling TrkA receptor proteostasis. Cell Mol Life Sci 2020; 77:2217-2233. [PMID: 31440771 PMCID: PMC11104797 DOI: 10.1007/s00018-019-03282-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 08/06/2019] [Accepted: 08/15/2019] [Indexed: 11/27/2022]
Abstract
The molecular mechanisms that control the biosynthetic trafficking, surface delivery, and degradation of TrkA receptor are essential for proper nerve growth factor (NGF) function, and remain poorly understood. Here, we identify Tetraspanin1 (Tspan1) as a critical regulator of TrkA signaling and neuronal differentiation induced by NGF. Tspan1 is expressed by developing TrkA-positive dorsal root ganglion (DRG) neurons and its downregulation in sensory neurons inhibits NGF-mediated axonal growth. In addition, our data demonstrate that Tspan1 forms a molecular complex with the immature form of TrkA localized in the endoplasmic reticulum (ER). Finally, knockdown of Tspan1 reduces the surface levels of TrkA by promoting its preferential sorting towards the autophagy/lysosomal degradation pathway. Together, these data establish a novel homeostatic role of Tspan1, coordinating the biosynthetic trafficking and degradation of TrkA, regardless the presence of NGF.
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Affiliation(s)
- Facundo Ferrero Restelli
- División de Neurobiología Molecular y Celular, Instituto de Biología Celular y Neurociencias (IBCN)-CONICET-UBA, Facultad de Medicina, University of Buenos Aires (UBA), CP1121, Buenos Aires, Argentina
| | - Paula Aldana Fontanet
- División de Neurobiología Molecular y Celular, Instituto de Biología Celular y Neurociencias (IBCN)-CONICET-UBA, Facultad de Medicina, University of Buenos Aires (UBA), CP1121, Buenos Aires, Argentina
| | - Ana Paula De Vincenti
- División de Neurobiología Molecular y Celular, Instituto de Biología Celular y Neurociencias (IBCN)-CONICET-UBA, Facultad de Medicina, University of Buenos Aires (UBA), CP1121, Buenos Aires, Argentina
| | - Tomás Luis Falzone
- Laboratorio de Transporte Axonal y Enfermedades Neurodegenerativas, Instituto de Biología Celular y Neurociencias (IBCN)-CONICET-UBA, Facultad de Medicina, University of Buenos Aires (UBA), CP1121, Buenos Aires, Argentina
| | - Fernanda Ledda
- División de Neurobiología Molecular y Celular, Instituto de Biología Celular y Neurociencias (IBCN)-CONICET-UBA, Facultad de Medicina, University of Buenos Aires (UBA), CP1121, Buenos Aires, Argentina
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA), CONICET, Buenos Aires, Argentina
| | - Gustavo Paratcha
- División de Neurobiología Molecular y Celular, Instituto de Biología Celular y Neurociencias (IBCN)-CONICET-UBA, Facultad de Medicina, University of Buenos Aires (UBA), CP1121, Buenos Aires, Argentina.
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18
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Abstract
The spinal cord receives, relays and processes sensory information from the periphery and integrates this information with descending inputs from supraspinal centres to elicit precise and appropriate behavioural responses and orchestrate body movements. Understanding how the spinal cord circuits that achieve this integration are wired during development is the focus of much research interest. Several families of proteins have well-established roles in guiding developing spinal cord axons, and recent findings have identified new axon guidance molecules. Nevertheless, an integrated view of spinal cord network development is lacking, and many current models have neglected the cellular and functional diversity of spinal cord circuits. Recent advances challenge the existing spinal cord axon guidance dogmas and have provided a more complex, but more faithful, picture of the ontogenesis of vertebrate spinal cord circuits.
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19
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Chen B, Carr L, Dun XP. Dynamic expression of Slit1-3 and Robo1-2 in the mouse peripheral nervous system after injury. Neural Regen Res 2020; 15:948-958. [PMID: 31719262 PMCID: PMC6990781 DOI: 10.4103/1673-5374.268930] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Slit family of axon guidance cues act as repulsive molecules for precise axon pathfinding and neuronal migration during nervous system development through interactions with specific Robo receptors. Although we previously reported that Slit1-3 and their receptors Robo1 and Robo2 are highly expressed in the adult mouse peripheral nervous system, how this expression changes after injury has not been well studied. Herein, we constructed a peripheral nerve injury mouse model by transecting the right sciatic nerve. At 14 days after injury, quantitative real-time polymerase chain reaction was used to detect mRNA expression of Slit1-3 and Robo1-2 in L4-5 spinal cord and dorsal root ganglia, as well as the sciatic nerve. Immunohistochemical analysis was performed to examine Slit1-3, Robo1-2, neurofilament heavy chain, F4/80, and vimentin in L4-5 spinal cord, L4 dorsal root ganglia, and the sciatic nerve. Co-expression of Slit1-3 and Robo1-2 in L4 dorsal root ganglia was detected by in situ hybridization. In addition, Slit1-3 and Robo1-2 protein expression in L4-5 spinal cord, L4 dorsal root ganglia, and sciatic nerve were detected by western blot assay. The results showed no significant changes of Slit1-3 or Robo1-2 mRNA expression in the spinal cord within 14 days after injury. In the dorsal root ganglion, Slit1-3 and Robo1-2 mRNA expression were initially downregulated within 4 days after injury; however, Robo1-2 mRNA expression returned to the control level, while Slit1-3 mRNA expression remained upregulated during regeneration from 4-14 days after injury. In the sciatic nerve, Slit1-3 and their receptors Robo1-2 were all expressed in the proximal nerve stump; however, Slit1, Slit2, and Robo2 were barely detectable in the nerve bridge and distal nerve stump within 14 days after injury. Slit3 was highly ex-pressed in macrophages surrounding the nerve bridge and slightly downregulated in the distal nerve stump within 14 days after injury. Robo1 was upregulated in vimentin-positive cells and migrating Schwann cells inside the nerve bridge. Robo1 was also upregulated in Schwann cells of the distal nerve stump within 14 days after injury. Our findings indicate that Slit3 is the major ligand expressed in the nerve bridge and distal nerve stump during peripheral nerve regeneration, and Slit3/Robo signaling could play a key role in peripheral nerve repair after injury. This study was approved by Plymouth University Animal Welfare Ethical Review Board (approval No. 30/3203) on April 12, 2014.
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Affiliation(s)
- Bing Chen
- Department of Neurology, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huai'an, Jiangsu Province, China
| | - Lauren Carr
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, UK
| | - Xin-Peng Dun
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, UK; The Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
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20
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Zhang Q, Zhao J, Shen J, Zhang X, Ren R, Ma Z, He Y, Kang Q, Wang Y, Dong X, Sun J, Liu Z, Yi X. The ATP-P2X7 Signaling Pathway Participates in the Regulation of Slit1 Expression in Satellite Glial Cells. Front Cell Neurosci 2019; 13:420. [PMID: 31607866 PMCID: PMC6761959 DOI: 10.3389/fncel.2019.00420] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 09/02/2019] [Indexed: 11/17/2022] Open
Abstract
Slit1 is one of the known signaling factors of the slit family and can promote neurite growth by binding to its receptor, Robo2. Upregulation of Slit1 expression in dorsal root ganglia (DRG) after peripheral nerve injury plays an important role in nerve regeneration. Each sensory neuronal soma in the DRG is encapsulated by several surrounding satellite glial cells (SGCs) to form a neural structural unit. However, the temporal and spatial patterns of Slit1 upregulation in SGCs in DRG and its molecular mechanisms are not well understood. This study examined the spatial and temporal patterns of Slit1 expression in DRG after sciatic nerve crush by immunohistochemistry and western blotting. The effect of neuronal damage signaling on the expression of Slit1 in SGCs was studied in vivo by fluorescent gold retrograde tracing and double immunofluorescence staining. The relationship between the expression of Slit1 in SGCs and neuronal somas was also observed by culturing DRG cells and double immunofluorescence labeling. The molecular mechanism of Slit1 was further explored by immunohistochemistry and western blotting after intraperitoneal injection of Bright Blue G (BBG, P2X7R inhibitor). The results showed that after peripheral nerve injury, the expression of Slit1 in the neurons and SGCs of DRG increased. The expression of Slit1 was presented with a time lag in SGCs than in neurons. The expression of Slit1 in SGCs was induced by contact with surrounding neuronal somas. Through injured cell localization, it was found that the expression of Slit1 was stronger in SGCs surrounding injured neurons than in SGCs surrounding non-injured neurons. The expression of vesicular nucleotide transporter (VNUT) in DRG neurons was increased by injury signaling. After the inhibition of P2X7R, the expression of Slit1 in SGCs was downregulated, and the expression of VNUT in DRG neurons was upregulated. These results indicate that the ATP-P2X7R pathway is involved in signal transduction from peripheral nerve injury to SGCs, leading to the upregulation of Slit1 expression.
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Affiliation(s)
- Quanpeng Zhang
- Department of Anatomy, Hainan Medical University, Haikou, China.,Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
| | - Jiuhong Zhao
- Department of Anatomy, Hainan Medical University, Haikou, China.,Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
| | - Jing Shen
- Department of Ophthalmology, First Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Xianfang Zhang
- Department of Anatomy, Hainan Medical University, Haikou, China.,Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
| | - Rui Ren
- Department of Anatomy, Hainan Medical University, Haikou, China.,Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
| | - Zhijian Ma
- Department of Anatomy, Hainan Medical University, Haikou, China.,Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
| | - Yuebin He
- Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
| | - Qian Kang
- Infection Control Department, People's Hospital of Xing'an County, Guilin, China
| | - Yanshan Wang
- Quality Inspection Department, Minghui Industry (Shenzhen) Co., Ltd., Shenzhen, China
| | - Xu Dong
- Hainan Provincial Key Laboratory of Carcinogenesis and Intervention, Hainan Medical University, Haikou, China
| | - Jin Sun
- Department of Clinical Medicine, Hainan Medical University, Haikou, China
| | - Zhuozhou Liu
- Department of Clinical Medicine, Hainan Medical University, Haikou, China
| | - Xinan Yi
- Department of Anatomy, Hainan Medical University, Haikou, China.,Joint Laboratory for Neuroscience, Hainan Medical University, Fourth Military Medical University, Haikou, China
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21
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Gasparini G, Pellegatta M, Crippa S, Lena MS, Belfiori G, Doglioni C, Taveggia C, Falconi M. Nerves and Pancreatic Cancer: New Insights into a Dangerous Relationship. Cancers (Basel) 2019; 11:E893. [PMID: 31248001 PMCID: PMC6678884 DOI: 10.3390/cancers11070893] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/21/2019] [Accepted: 06/24/2019] [Indexed: 12/24/2022] Open
Abstract
Perineural invasion (PNI) is defined as the presence of neoplastic cells along nerves and/or within the different layers of nervous fibers: epineural, perineural and endoneural spaces. In pancreatic cancer-particularly in pancreatic ductal adenocarcinoma (PDAC)-PNI has a prevalence between 70 and 100%, surpassing any other solid tumor. PNI has been detected in the early stages of pancreatic cancer and has been associated with pain, increased tumor recurrence and diminished overall survival. Such an early, invasive and recurrent phenomenon is probably crucial for tumor growth and metastasis. PNI is a still not a uniformly characterized event; usually it is described only dichotomously ("present" or "absent"). Recently, a more detailed scoring system for PNI has been proposed, though not specific for pancreatic cancer. Previous studies have implicated several molecules and pathways in PNI, among which are secreted neurotrophins, chemokines and inflammatory cells. However, the mechanisms underlying PNI are poorly understood and several aspects are actively being investigated. In this review, we will discuss the main molecules and signaling pathways implicated in PNI and their roles in the PDAC.
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Affiliation(s)
- Giulia Gasparini
- Pancreas Translational & Clinical Research Center, Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
- Axo-Glial Interaction Unit, INSPE, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
| | - Marta Pellegatta
- Axo-Glial Interaction Unit, INSPE, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
| | - Stefano Crippa
- Pancreas Translational & Clinical Research Center, Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
- Vita Salute San Raffaele University, 20132 Milan, Italy.
| | - Marco Schiavo Lena
- Pathology Unit, Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
| | - Giulio Belfiori
- Pancreas Translational & Clinical Research Center, Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
| | - Claudio Doglioni
- Vita Salute San Raffaele University, 20132 Milan, Italy.
- Pathology Unit, Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
| | - Carla Taveggia
- Axo-Glial Interaction Unit, INSPE, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
| | - Massimo Falconi
- Pancreas Translational & Clinical Research Center, Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
- Vita Salute San Raffaele University, 20132 Milan, Italy.
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22
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Jiang Z, Liang G, Xiao Y, Qin T, Chen X, Wu E, Ma Q, Wang Z. Targeting the SLIT/ROBO pathway in tumor progression: molecular mechanisms and therapeutic perspectives. Ther Adv Med Oncol 2019; 11:1758835919855238. [PMID: 31217826 PMCID: PMC6557020 DOI: 10.1177/1758835919855238] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/07/2019] [Indexed: 01/14/2023] Open
Abstract
The SLITs (SLIT1, SLIT2, and SLIT3) are a family of secreted proteins that mediate positional interactions between cells and their environment during development by signaling through ROBO receptors (ROBO1, ROBO2, ROBO3, and ROBO4). The SLIT/ROBO signaling pathway has been shown to participate in axonal repulsion, axon guidance, and neuronal migration in the nervous system and the formation of the vascular system. However, the role of the SLIT/ROBO pathway has not been thoroughly clarified in tumor development. The SLIT/ROBO pathway can produce both beneficial and detrimental effects in the growth of malignant cells. It has been confirmed that SLIT/ROBO play contradictory roles in tumorigenesis. Here, we discuss the tumor promotion and tumor suppression roles of the SLIT/ROBO pathway in tumor growth, angiogenesis, migration, and the tumor microenvironment. Understanding these roles will help us develop more effective cancer therapies.
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Affiliation(s)
- Zhengdong Jiang
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Gang Liang
- Department of Hepatobiliary Surgery, No. 215 Hospital of Shaanxi Nuclear Industry, Xianyang, Shaanxi, China
| | - Ying Xiao
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Tao Qin
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xin Chen
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Erxi Wu
- Department of Neurosurgery, Neuroscience Institute, Baylor Scott and White Health, Temple, TX, USA
| | - Qingyong Ma
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
| | - Zheng Wang
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
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23
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Gruner HN, Kim M, Mastick GS. Robo1 and 2 Repellent Receptors Cooperate to Guide Facial Neuron Cell Migration and Axon Projections in the Embryonic Mouse Hindbrain. Neuroscience 2019; 402:116-129. [PMID: 30685539 PMCID: PMC6435285 DOI: 10.1016/j.neuroscience.2019.01.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 01/12/2019] [Accepted: 01/14/2019] [Indexed: 11/19/2022]
Abstract
The facial nerve is necessary for our ability to eat, speak, and make facial expressions. Both the axons and cell bodies of the facial nerve undergo a complex embryonic developmental pattern involving migration of the cell bodies caudally and tangentially through rhombomeres, and simultaneously the axons projecting to exit the hindbrain to form the facial nerve. Our goal in this study was to test the functions of the chemorepulsive receptors Robo1 and Robo2 in facial neuron migration and axon projection by analyzing genetically marked motor neurons in double-mutant mouse embryos through the migration time course, E10.0-E13.5. In Robo1/2 double mutants, axon projection and cell body migration errors were more severe than in single mutants. Most axons did not make it to their motor exit point, and instead projected into and longitudinally within the floor plate. Surprisingly, some facial neurons had multiple axons exiting and projecting into the floor plate. At the same time, a subset of mutant facial cell bodies failed to migrate caudally, and instead either streamed dorsally toward the exit point or shifted into the floor plate. We conclude that Robo1 and Robo2 have redundant functions to guide multiple aspects of the complex cell migration of the facial nucleus, as well as regulating axon trajectories and suppressing formation of ectopic axons.
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Affiliation(s)
- Hannah N. Gruner
- Department of Biology, University of Nevada, 1664 N Virginia St, Reno, NV 89557, USA.
| | - Minkyung Kim
- Department of Biology, University of Nevada, 1664 N Virginia St, Reno, NV 89557, USA.
| | - Grant S. Mastick
- Department of Biology, University of Nevada, 1664 N Virginia St, Reno, NV 89557, USA.
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24
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Kitazawa T, Rijli FM. Barrelette map formation in the prenatal mouse brainstem. Curr Opin Neurobiol 2018; 53:210-219. [PMID: 30342228 DOI: 10.1016/j.conb.2018.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/03/2018] [Accepted: 09/24/2018] [Indexed: 12/30/2022]
Abstract
The rodent whiskers are topographically mapped in brainstem sensory nuclei as neuronal modules known as barrelettes. Little is known about how the facial whisker pattern is copied into a brainstem barrelette topographic pattern, which serves as a template for the establishment of thalamic barreloid and, in turn, cortical barrel maps, and how precisely is the whisker pattern mapped in the brainstem during prenatal development. Here, we review recent insights advancing our understanding of the intrinsic and extrinsic patterning mechanisms contributing to establish topographical equivalence between the facial whisker pattern and the mouse brainstem during prenatal development and their relative importance.
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Affiliation(s)
- Taro Kitazawa
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4051 Basel, Switzerland
| | - Filippo M Rijli
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4051 Basel, Switzerland; University of Basel, 4003 Basel, Switzerland.
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Regulation of the Natriuretic Peptide Receptor 2 (Npr2) by Phosphorylation of Juxtamembrane Serine and Threonine Residues Is Essential for Bifurcation of Sensory Axons. J Neurosci 2018; 38:9768-9780. [PMID: 30249793 DOI: 10.1523/jneurosci.0495-18.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 08/28/2018] [Accepted: 09/18/2018] [Indexed: 12/31/2022] Open
Abstract
cGMP signaling elicited by activation of the transmembrane receptor guanylyl cyclase Npr2 (also known as guanylyl cyclase B) by the ligand CNP controls sensory axon bifurcation of DRG and cranial sensory ganglion (CSG) neurons entering the spinal cord or hindbrain, respectively. Previous studies have shown that Npr2 is phosphorylated on serine and threonine residues in its kinase homology domain (KHD). However, it is unknown whether phosphorylation of Npr2 is essential for axon bifurcation. Here, we generated a knock-in mouse line in which the seven regulatory serine and threonine residues in the KHD of Npr2 were substituted by alanine (Npr2-7A), resulting in a nonphosphorylatable enzyme. Real-time imaging of cGMP in DRG neurons with a genetically encoded fluorescent cGMP sensor or biochemical analysis of guanylyl cyclase activity in brain or lung tissue revealed the absence of CNP-induced cGMP generation in the Npr27A/7A mutant. Consequently, bifurcation of axons, but not collateral formation, from DRG or CSG in this mouse mutant was perturbed at embryonic and mature stages. In contrast, axon branching was normal in a mouse mutant in which constitutive phosphorylation of Npr2 is mimicked by a replacement of all of the seven serine and threonine sites by glutamic acid (Npr2-7E). Furthermore, we demonstrate that the Npr27A/7A mutation causes dwarfism as described for global Npr2 mutants. In conclusion, our in vivo studies provide strong evidence that phosphorylation of the seven serine and threonine residues in the KHD of Npr2 is an important regulatory element of Npr2-mediated cGMP signaling which affects physiological processes, such as axon bifurcation and bone growth.SIGNIFICANCE STATEMENT The branching of axons is a morphological hallmark of virtually all neurons. It allows an individual neuron to innervate different targets and to communicate with neurons located in different regions of the nervous system. The natriuretic peptide receptor 2 (Npr2), a transmembrane guanylyl cyclase, is essential for the initiation of bifurcation of sensory axons when entering the spinal cord or the hindbrain. By using two genetically engineered mouse lines, we show that phosphorylation of specific serine and threonine residues in juxtamembrane regions of Npr2 are required for its enzymatic activity and for axon bifurcation. These investigations might help to understand the regulation of Npr2 and its integration in intracellular signaling systems.
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CD30 Is Highly Expressed in Chronic Obstructive Pulmonary Disease and Induces the Pulmonary Vascular Remodeling. BIOMED RESEARCH INTERNATIONAL 2018; 2018:3261436. [PMID: 29984229 PMCID: PMC6015698 DOI: 10.1155/2018/3261436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 03/26/2018] [Indexed: 11/18/2022]
Abstract
Chronic obstructive pulmonary disease (COPD) is one of the common and underdiagnosed diseases with the highest morbidity and mortality in the world. The development of COPD can lead to pulmonary vascular remodeling and pulmonary hypertension, further causing the occurrence of pulmonary heart disease. Therefore, attenuation of pulmonary vascular remodeling and pulmonary hypertension caused by COPD can significantly delay cardiovascular complications. In the study, we firstly found that the expression of CD30 and CD30L was increased in COPD. Importantly, the serum CD30L levels were significantly higher in patients with stable COPD relative to those with acute exacerbation of COPD (AECOPD). This suggested that CD30 might be related to the development of COPD. In addition, we found that the expression of CD30 in the COPD rat model was significantly increased compared with control group. And treatment with the anti-CD30 antibody reduced the serum concentration and tissue expression of CD30 in rat. Importantly, anti-CD30 antibody alleviated pulmonary vascular remodeling in COPD model rats. This suggested that CD30 played an important role in the course of COPD. Finally, we found that, in the HPASMC and HPAEC cell lines, CD30 can affect the cell viability and cell migration and inhibited hypoxia-induced cell apoptosis in a concentration-dependent manner. We also found CD30 induced extracellular matrix formation through decreasing the expression of MMP-2, thus promoting the pulmonary vascular remodeling. The study indicated that CD30 and CD30L were involved in pulmonary vascular remodeling and inflammatory response in COPD. Altogether, CD30 might be a marker for the early diagnosis and progression of COPD.
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Vahedi-Hunter TA, Estep JA, Rosette KA, Rutlin ML, Wright KM, Riccomagno MM. Cas Adaptor Proteins Coordinate Sensory Axon Fasciculation. Sci Rep 2018; 8:5996. [PMID: 29662228 PMCID: PMC5902548 DOI: 10.1038/s41598-018-24261-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 03/29/2018] [Indexed: 11/09/2022] Open
Abstract
Development of complex neural circuits like the peripheral somatosensory system requires intricate mechanisms to ensure axons make proper connections. While much is known about ligand-receptor pairs required for dorsal root ganglion (DRG) axon guidance, very little is known about the cytoplasmic effectors that mediate cellular responses triggered by these guidance cues. Here we show that members of the Cas family of cytoplasmic signaling adaptors are highly phosphorylated in central projections of the DRG as they enter the spinal cord. Furthermore, we provide genetic evidence that Cas proteins regulate fasciculation of DRG sensory projections. These data establish an evolutionarily conserved requirement for Cas adaptor proteins during peripheral nervous system axon pathfinding. They also provide insight into the interplay between axonal fasciculation and adhesion to the substrate.
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Affiliation(s)
- Tyler A Vahedi-Hunter
- Neuroscience Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Jason A Estep
- Cell, Molecular and Developmental Biology Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Kylee A Rosette
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Michael L Rutlin
- Department of Biochemistry and Molecular Biophysics, Columbia College of Physicians and Surgeons, Columbia University, New York, New York, 10032, USA
| | - Kevin M Wright
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Martin M Riccomagno
- Neuroscience Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA. .,Cell, Molecular and Developmental Biology Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA.
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28
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Spurlin JW, Nelson CM. Building branched tissue structures: from single cell guidance to coordinated construction. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2015.0527. [PMID: 28348257 DOI: 10.1098/rstb.2015.0527] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2016] [Indexed: 12/15/2022] Open
Abstract
Branched networks are ubiquitous throughout nature, particularly found in tissues that require large surface area within a restricted volume. Many tissues with a branched architecture, such as the vasculature, kidney, mammary gland, lung and nervous system, function to exchange fluids, gases and information throughout the body of an organism. The generation of branched tissues requires regulation of branch site specification, initiation and elongation. Branching events often require the coordination of many cells to build a tissue network for material exchange. Recent evidence has emerged suggesting that cell cooperativity scales with the number of cells actively contributing to branching events. Here, we compare mechanisms that regulate branching, focusing on how cell cohorts behave in a coordinated manner to build branched tissues.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
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Affiliation(s)
- James W Spurlin
- Departments of Chemical and Biological Engineering, Princeton University, 303 Hoyt Laboratory, William Street, Princeton, NJ 08544, USA
| | - Celeste M Nelson
- Departments of Chemical and Biological Engineering, Princeton University, 303 Hoyt Laboratory, William Street, Princeton, NJ 08544, USA .,Molecular Biology, Princeton University, 303 Hoyt Laboratory, William Street, Princeton, NJ 08544, USA
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29
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Studying the role of axon fasciculation during development in a computational model of the Xenopus tadpole spinal cord. Sci Rep 2017; 7:13551. [PMID: 29051550 PMCID: PMC5648846 DOI: 10.1038/s41598-017-13804-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/03/2017] [Indexed: 11/21/2022] Open
Abstract
During nervous system development growing axons can interact with each other, for example by adhering together in order to produce bundles (fasciculation). How does such axon-axon interaction affect the resulting axonal trajectories, and what are the possible benefits of this process in terms of network function? In this paper we study these questions by adapting an existing computational model of the development of neurons in the Xenopus tadpole spinal cord to include interactions between axons. We demonstrate that even relatively weak attraction causes bundles to appear, while if axons weakly repulse each other their trajectories diverge such that they fill the available space. We show how fasciculation can help to ensure axons grow in the correct location for proper network formation when normal growth barriers contain gaps, and use a functional spiking model to show that fasciculation allows the network to generate reliable swimming behaviour even when overall synapse counts are artificially lowered. Although we study fasciculation in one particular organism, our approach to modelling axon growth is general and can be widely applied to study other nervous systems.
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Abstract
Recent studies have demonstrated a critical role for nerves in enabling tumor progression. The association of nerves with cancer cells is well established for a variety of malignant tumors, including pancreatic, prostate and the head and neck cancers. This association is often correlated with poor prognosis. A strong partnership between cancer cells and nerve cells leads to both cancer progression and expansion of the nerve network. This relationship is supported by molecular pathways related to nerve growth and repair. Peripheral nerves form complex tumor microenvironments, which are made of several cell types including Schwann cells. Recent studies have revealed that Schwann cells enable cancer progression by adopting a de-differentiated phenotype, similar to the Schwann cell response to nerve trauma. A detailed understanding of the molecular and cellular mechanisms involved in the regulation of cancer progression by the nerves is essential to design strategies to inhibit tumor progression.
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Carr L, Parkinson DB, Dun XP. Expression patterns of Slit and Robo family members in adult mouse spinal cord and peripheral nervous system. PLoS One 2017; 12:e0172736. [PMID: 28234971 PMCID: PMC5325304 DOI: 10.1371/journal.pone.0172736] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/08/2017] [Indexed: 11/19/2022] Open
Abstract
The secreted glycoproteins, Slit1-3, are classic axon guidance molecules that act as repulsive cues through their well characterised receptors Robo1-2 to allow precise axon pathfinding and neuronal migration. The expression patterns of Slit1-3 and Robo1-2 have been most characterized in the rodent developing nervous system and the adult brain, but little is known about their expression patterns in the adult rodent peripheral nervous system. Here, we report a detailed expression analysis of Slit1-3 and Robo1-2 in the adult mouse sciatic nerve as well as their expression in the nerve cell bodies within the ventral spinal cord (motor neurons) and dorsal root ganglion (sensory neurons). Our results show that, in the adult mouse peripheral nervous system, Slit1-3 and Robo1-2 are expressed in the cell bodies and axons of both motor and sensory neurons. While Slit1 and Robo2 are only expressed in peripheral axons and their cell bodies, Slit2, Slit3 and Robo1 are also expressed in satellite cells of the dorsal root ganglion, Schwann cells and fibroblasts of peripheral nerves. In addition to these expression patterns, we also demonstrate the expression of Robo1 in blood vessels of the peripheral nerves. Our work gives important new data on the expression patterns of Slit and Robo family members within the peripheral nervous system that may relate both to nerve homeostasis and the reaction of the peripheral nerves to injury.
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Affiliation(s)
- Lauren Carr
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, Devon, United Kingdom
| | - David B. Parkinson
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, Devon, United Kingdom
| | - Xin-peng Dun
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, Devon, United Kingdom
- Hubei University of Science and Technology, Xian-Ning City, Hubei, China
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32
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MAP7 Regulates Axon Collateral Branch Development in Dorsal Root Ganglion Neurons. J Neurosci 2017; 37:1648-1661. [PMID: 28069923 DOI: 10.1523/jneurosci.3260-16.2017] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/27/2016] [Accepted: 01/04/2017] [Indexed: 01/26/2023] Open
Abstract
Collateral branches from axons are key components of functional neural circuits that allow neurons to connect with multiple synaptic targets. Like axon growth and guidance, formation of collateral branches depends on the regulation of microtubules, but how such regulation is coordinated to ensure proper circuit development is not known. Based on microarray analysis, we have identified a role for microtubule-associated protein 7 (MAP7) during collateral branch development of dorsal root ganglion (DRG) sensory neurons. We show that MAP7 is expressed at the onset of collateral branch formation. Perturbation of its expression by overexpression or shRNA knockdown alters axon branching in cultured DRG neurons. Localization and time-lapse imaging analysis reveals that MAP7 is enriched at branch points and colocalizes with stable microtubules, but enters the new branch with a delay, suggesting a role in branch maturation. We have also investigated a spontaneous mutant mouse that expresses a truncated MAP7 and found a gain-of-function phenotype both in vitro and in vivo Further domain analysis suggests that the amino half of MAP7 is responsible for branch formation, suggesting a mechanism that is independent of its known interaction with kinesin. Moreover, this mouse exhibits increased pain sensitivity, a phenotype that is consistent with increased collateral branch formation. Therefore, our study not only uncovers the first neuronal function of MAP7, but also demonstrates the importance of proper microtubule regulation in neural circuit development. Furthermore, our data provide new insights into microtubule regulation during axonal morphogenesis and may shed light on MAP7 function in neurological disorders.SIGNIFICANCE STATEMENT Neurons communicate with multiple targets by forming axonal branches. In search of intrinsic factors that control collateral branch development, we identified a role for microtubule-associated protein 7 (MAP7) in dorsal root ganglion sensory neurons. We show that MAP7 expression is developmentally regulated and perturbation of this expression alters branch formation. Cell biological analysis indicates that MAP7 promotes branch maturation. Analysis of a spontaneous mouse mutant suggests a molecular mechanism for branch regulation and the potential influence of collateral branches on pain sensitivity. Our studies thus establish the first neuronal function of MAP7 and demonstrate its role in branch morphogenesis and neural circuit function. These findings may help in our understanding of the contribution of MAP7 to neurological disorders and nerve regeneration.
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ISL1-based LIM complexes control Slit2 transcription in developing cranial motor neurons. Sci Rep 2016; 6:36491. [PMID: 27819291 PMCID: PMC5098159 DOI: 10.1038/srep36491] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/17/2016] [Indexed: 01/02/2023] Open
Abstract
LIM-homeodomain (HD) transcription factors form a multimeric complex and assign neuronal subtype identities, as demonstrated by the hexameric ISL1-LHX3 complex which gives rise to somatic motor (SM) neurons. However, the roles of combinatorial LIM code in motor neuron diversification and their subsequent differentiation is much less well understood. In the present study, we demonstrate that the ISL1 controls postmitotic cranial branchiomotor (BM) neurons including the positioning of the cell bodies and peripheral axon pathfinding. Unlike SM neurons, which transform into interneurons, BM neurons are normal in number and in marker expression in Isl1 mutant mice. Nevertheless, the movement of trigeminal and facial BM somata is stalled, and their peripheral axons are fewer or misrouted, with ectopic branches. Among genes whose expression level changes in previous ChIP-seq and microarray analyses in Isl1-deficient cell lines, we found that Slit2 transcript was almost absent from BM neurons of Isl1 mutants. Both ISL1-LHX3 and ISL1-LHX4 bound to the Slit2 enhancer and drove endogenous Slit2 expression in SM and BM neurons. Our findings suggest that combinations of ISL1 and LHX factors establish cell-type specificity and functional diversity in terms of motor neuron identities and/or axon development.
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34
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Chakraborty M, Jarvis ED. Brain evolution by brain pathway duplication. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0056. [PMID: 26554045 PMCID: PMC4650129 DOI: 10.1098/rstb.2015.0056] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Understanding the mechanisms of evolution of brain pathways for complex behaviours is still in its infancy. Making further advances requires a deeper understanding of brain homologies, novelties and analogies. It also requires an understanding of how adaptive genetic modifications lead to restructuring of the brain. Recent advances in genomic and molecular biology techniques applied to brain research have provided exciting insights into how complex behaviours are shaped by selection of novel brain pathways and functions of the nervous system. Here, we review and further develop some insights to a new hypothesis on one mechanism that may contribute to nervous system evolution, in particular by brain pathway duplication. Like gene duplication, we propose that whole brain pathways can duplicate and the duplicated pathway diverge to take on new functions. We suggest that one mechanism of brain pathway duplication could be through gene duplication, although other mechanisms are possible. We focus on brain pathways for vocal learning and spoken language in song-learning birds and humans as example systems. This view presents a new framework for future research in our understanding of brain evolution and novel behavioural traits.
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Affiliation(s)
- Mukta Chakraborty
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27713, USA Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Erich D Jarvis
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27713, USA Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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35
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Ito H, Sato K, Kondo S, Ueda R, Yamamoto D. Fruitless Represses robo1 Transcription to Shape Male-Specific Neural Morphology and Behavior in Drosophila. Curr Biol 2016; 26:1532-1542. [PMID: 27265393 DOI: 10.1016/j.cub.2016.04.067] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 04/21/2016] [Accepted: 04/27/2016] [Indexed: 11/17/2022]
Abstract
The Drosophila fruitless (fru) gene is regarded as a master regulator of the formation of male courtship circuitry, yet little is known about its molecular basis of action. We show that roundabout 1 (robo1) knockdown in females promotes formation of the male-specific neurite in sexually dimorphic mAL interneurons and that overexpression of the male-specific Fru(BM) diminishes the expression of Robo1 in the fly brain. Our electrophoretic mobility shift and reporter assays identify the 42-bp segment encompassing the palindrome sequence T T C G C T G C G C C G T G A A in the 5' UTR of robo1 exon1 as the Fru(BM)-responsive element. We find that ∼10-bp deletions in the palindrome sequence induce a loss of the male-specific neurite and disrupt male courtship patterns. This study paves the way for a thorough understanding of the mechanism whereby Fru proteins orchestrate transcription for the formation of courtship circuitry.
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Affiliation(s)
- Hiroki Ito
- Division of Neurogenetics, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan
| | - Kosei Sato
- Division of Neurogenetics, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan
| | - Shu Kondo
- National Institute of Genetics, Mishima 411-8540, Japan
| | - Ryu Ueda
- National Institute of Genetics, Mishima 411-8540, Japan
| | - Daisuke Yamamoto
- Division of Neurogenetics, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan.
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36
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McConnell RE, Edward van Veen J, Vidaki M, Kwiatkowski AV, Meyer AS, Gertler FB. A requirement for filopodia extension toward Slit during Robo-mediated axon repulsion. J Cell Biol 2016; 213:261-74. [PMID: 27091449 PMCID: PMC5084274 DOI: 10.1083/jcb.201509062] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 03/04/2016] [Indexed: 12/11/2022] Open
Abstract
Axons navigate long distances through complex 3D environments to interconnect the nervous system during development. Although the precise spatiotemporal effects of most axon guidance cues remain poorly characterized, a prevailing model posits that attractive guidance cues stimulate actin polymerization in neuronal growth cones whereas repulsive cues induce actin disassembly. Contrary to this model, we find that the repulsive guidance cue Slit stimulates the formation and elongation of actin-based filopodia from mouse dorsal root ganglion growth cones. Surprisingly, filopodia form and elongate toward sources of Slit, a response that we find is required for subsequent axonal repulsion away from Slit. Mechanistically, Slit evokes changes in filopodium dynamics by increasing direct binding of its receptor, Robo, to members of the actin-regulatory Ena/VASP family. Perturbing filopodium dynamics pharmacologically or genetically disrupts Slit-mediated repulsion and produces severe axon guidance defects in vivo. Thus, Slit locally stimulates directional filopodial extension, a process that is required for subsequent axonal repulsion downstream of the Robo receptor.
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Affiliation(s)
- Russell E McConnell
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 01239
| | - J Edward van Veen
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 01239 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 01239
| | - Marina Vidaki
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 01239
| | - Adam V Kwiatkowski
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 01239
| | - Aaron S Meyer
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 01239 Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 01239
| | - Frank B Gertler
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 01239 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 01239
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37
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Short B. Slit holds a strange attraction for filopodia. J Biophys Biochem Cytol 2016. [DOI: 10.1083/jcb.2132if] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The guidance cue Slit induces axonal repulsion by directing the extension of growth cone filopodia.
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38
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Tillo M, Charoy C, Schwarz Q, Maden CH, Davidson K, Fantin A, Ruhrberg C. 2- and 6-O-sulfated proteoglycans have distinct and complementary roles in cranial axon guidance and motor neuron migration. Development 2016; 143:1907-13. [PMID: 27048738 PMCID: PMC4920156 DOI: 10.1242/dev.126854] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 03/29/2016] [Indexed: 12/13/2022]
Abstract
The correct migration and axon extension of neurons in the developing nervous system is essential for the appropriate wiring and function of neural networks. Here, we report that O-sulfotransferases, a class of enzymes that modify heparan sulfate proteoglycans (HSPGs), are essential to regulate neuronal migration and axon development. We show that the 6-O-sulfotransferases HS6ST1 and HS6ST2 are essential for cranial axon patterning, whilst the 2-O-sulfotransferase HS2ST (also known as HS2ST1) is important to regulate the migration of facial branchiomotor (FBM) neurons in the hindbrain. We have also investigated how HS2ST interacts with other signals in the hindbrain and show that fibroblast growth factor (FGF) signalling regulates FBM neuron migration in an HS2ST-dependent manner. Summary: 2-O-sulfated proteoglycans are essential for cranial motor neuron migration, whereas 6-O-sulfated proteoglycans regulate cranial axon guidance.
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Affiliation(s)
- Miguel Tillo
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Camille Charoy
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Quenten Schwarz
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Charlotte H Maden
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Kathryn Davidson
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Alessandro Fantin
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Christiana Ruhrberg
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK Yale Cardiovascular Research Centre, Yale University, New Haven, CT 06511, USA
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39
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Branchfield K, Nantie L, Verheyden JM, Sui P, Wienhold MD, Sun X. Pulmonary neuroendocrine cells function as airway sensors to control lung immune response. Science 2016; 351:707-10. [PMID: 26743624 PMCID: PMC4860346 DOI: 10.1126/science.aad7969] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/16/2015] [Indexed: 12/16/2022]
Abstract
The lung is constantly exposed to environmental atmospheric cues. How it senses and responds to these cues is poorly defined. Here, we show that Roundabout receptor (Robo) genes are expressed in pulmonary neuroendocrine cells (PNECs), a rare, innervated epithelial population. Robo inactivation in mouse lung results in an inability of PNECs to cluster into sensory organoids and triggers increased neuropeptide production upon exposure to air. Excess neuropeptides lead to an increase in immune infiltrates, which in turn remodel the matrix and irreversibly simplify the alveoli. We demonstrate in vivo that PNECs act as precise airway sensors that elicit immune responses via neuropeptides. These findings suggest that the PNEC and neuropeptide abnormalities documented in a wide array of pulmonary diseases may profoundly affect symptoms and progression.
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Affiliation(s)
- Kelsey Branchfield
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Leah Nantie
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jamie M Verheyden
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Pengfei Sui
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Mark D Wienhold
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Xin Sun
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.
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40
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Amin ND, Bai G, Klug JR, Bonanomi D, Pankratz MT, Gifford WD, Hinckley CA, Sternfeld MJ, Driscoll SP, Dominguez B, Lee KF, Jin X, Pfaff SL. Loss of motoneuron-specific microRNA-218 causes systemic neuromuscular failure. Science 2016; 350:1525-9. [PMID: 26680198 DOI: 10.1126/science.aad2509] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dysfunction of microRNA (miRNA) metabolism is thought to underlie diseases affecting motoneurons. One miRNA, miR-218, is abundantly and selectively expressed by developing and mature motoneurons. Here we show that mutant mice lacking miR-218 die neonatally and exhibit neuromuscular junction defects, motoneuron hyperexcitability, and progressive motoneuron cell loss, all of which are hallmarks of motoneuron diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy. Gene profiling reveals that miR-218 modestly represses a cohort of hundreds of genes that are neuronally enriched but are not specific to a single neuron subpopulation. Thus, the set of messenger RNAs targeted by miR-218, designated TARGET(218), defines a neuronal gene network that is selectively tuned down in motoneurons to prevent neuromuscular failure and neurodegeneration.
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Affiliation(s)
- Neal D Amin
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. Medical Scientist Training Program, University of California, San Diego (UCSD), 9500 Gilman Drive, La Jolla, CA 92037, USA. Biomedical Sciences Graduate Program, UCSD, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Ge Bai
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jason R Klug
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Dario Bonanomi
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Matthew T Pankratz
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Wesley D Gifford
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. Medical Scientist Training Program, University of California, San Diego (UCSD), 9500 Gilman Drive, La Jolla, CA 92037, USA. Neurosciences Graduate Program, UCSD, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Christopher A Hinckley
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Matthew J Sternfeld
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. Biological Sciences Graduate Program, UCSD, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Shawn P Driscoll
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Bertha Dominguez
- Peptide Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Kuo-Fen Lee
- Peptide Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Xin Jin
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Samuel L Pfaff
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Leong WY, Lim ZH, Korzh V, Pietri T, Goh ELK. Methyl-CpG Binding Protein 2 (Mecp2) Regulates Sensory Function Through Sema5b and Robo2. Front Cell Neurosci 2015; 9:481. [PMID: 26733807 PMCID: PMC4685056 DOI: 10.3389/fncel.2015.00481] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/30/2015] [Indexed: 12/31/2022] Open
Abstract
Mutations in the gene encoding the MECP2 underlies Rett syndrome, a neurodevelopmental disorder in young females. Although reduced pain sensitivity in Rett syndrome patients and in partial MeCP2 deficient mice had been reported, these previous studies focused predominantly on motor impairments. Therefore, it is still unknown how MeCP2 is involved in these sensory defects. In addition, the human disease manifestations where males with mutations in MECP2 gene normally do not survive and females show typical neurological symptoms only after 18 months of age, is profoundly different in MeCP2-deficient mouse where all animals survived, and males but not females displayed Rett syndrome phenotypes at an early age. Thus, the mecp2-deficient zebrafish serves as an additional animal model to aid in deciphering the role and mechanisms of Mecp2 in neurodevelopment. Here, we used two independent methods of silencing expression of Mecp2 in zebrafish to uncover a novel role of Mecp2 in trigeminal ganglion sensory neurons during the embryonic development. mecp2-null mutation and morpholino-mediated silencing of Mecp2 in the zebrafish embryos resulted in defects in peripheral innervation of trigeminal sensory neurons and consequently affecting the sensory function. These defects were demonstrated to be dependent on the expression of Sema5b and Robo2. The expression of both proteins together could better overcome the defects caused by Mecp2 deficiency as compared to the expression of either Sema5b or Robo2 alone. Sema5b and Robo2 were downregulated upon Mecp2 silencing or in mecp2-null embryos, and Chromatin immunoprecipitation (ChIP) assay using antibody against Mecp2 was able to pull down specific regions of both Sema5b and Robo2 promoters, showing interaction between Mecp2 and the promoters of both genes. In addition, cell-specific expression of Mecp2 can overcome the innervation and sensory response defects in Mecp2 morphants indicating that these MeCP2-mediated defects are cell-autonomous. The sensory deficits caused by Mecp2 deficiency mirror the diminished sensory response observed in Rett syndrome patients. This suggests that zebrafish could be an unconventional but useful model for this disorder manifesting defects that are not easily studied in full using rodent models.
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Affiliation(s)
- Wan Y Leong
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School, Singapore Singapore
| | - Zhi H Lim
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School, Singapore Singapore
| | - Vladimir Korzh
- Institute of Molecular and Cell Biology, SingaporeSingapore; Department of Biological Sciences, National University of Singapore, SingaporeSingapore
| | - Thomas Pietri
- Institut de Biologie de l'École Normale Supérieure, Institut National de la Santé et de la Recherche Médicale U1024, Centre National de la Recherche Scientifique UMR 8197 Paris, France
| | - Eyleen L K Goh
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School, SingaporeSingapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, SingaporeSingapore; KK Research Centre, KK Women's and Children's Hospital, SingaporeSingapore
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CMT2D neuropathy is linked to the neomorphic binding activity of glycyl-tRNA synthetase. Nature 2015; 526:710-4. [PMID: 26503042 PMCID: PMC4754353 DOI: 10.1038/nature15510] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 08/21/2015] [Indexed: 12/22/2022]
Abstract
Selective neuronal loss is a hallmark of neurodegenerative diseases, which, counterintuitively, are often caused by mutations in widely expressed genes. Charcot-Marie-Tooth (CMT) diseases are the most common hereditary peripheral neuropathies, for which there are no effective therapies. A subtype of these diseases--CMT type 2D (CMT2D)--is caused by dominant mutations in GARS, encoding the ubiquitously expressed enzyme glycyl-transfer RNA (tRNA) synthetase (GlyRS). Despite the broad requirement of GlyRS for protein biosynthesis in all cells, mutations in this gene cause a selective degeneration of peripheral axons, leading to deficits in distal motor function. How mutations in GlyRS (GlyRS(CMT2D)) are linked to motor neuron vulnerability has remained elusive. Here we report that GlyRS(CMT2D) acquires a neomorphic binding activity that directly antagonizes an essential signalling pathway for motor neuron survival. We find that CMT2D mutations alter the conformation of GlyRS, enabling GlyRS(CMT2D) to bind the neuropilin 1 (Nrp1) receptor. This aberrant interaction competitively interferes with the binding of the cognate ligand vascular endothelial growth factor (VEGF) to Nrp1. Genetic reduction of Nrp1 in mice worsens CMT2D symptoms, whereas enhanced expression of VEGF improves motor function. These findings link the selective pathology of CMT2D to the neomorphic binding activity of GlyRS(CMT2D) that antagonizes the VEGF-Nrp1 interaction, and indicate that the VEGF-Nrp1 signalling axis is an actionable target for treating CMT2D.
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Chance RK, Bashaw GJ. Slit-Dependent Endocytic Trafficking of the Robo Receptor Is Required for Son of Sevenless Recruitment and Midline Axon Repulsion. PLoS Genet 2015; 11:e1005402. [PMID: 26335920 PMCID: PMC4559387 DOI: 10.1371/journal.pgen.1005402] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/26/2015] [Indexed: 01/07/2023] Open
Abstract
Understanding how axon guidance receptors are activated by their extracellular ligands to regulate growth cone motility is critical to learning how proper wiring is established during development. Roundabout (Robo) is one such guidance receptor that mediates repulsion from its ligand Slit in both invertebrates and vertebrates. Here we show that endocytic trafficking of the Robo receptor in response to Slit-binding is necessary for its repulsive signaling output. Dose-dependent genetic interactions and in vitro Robo activation assays support a role for Clathrin-dependent endocytosis, and entry into both the early and late endosomes as positive regulators of Slit-Robo signaling. We identify two conserved motifs in Robo's cytoplasmic domain that are required for its Clathrin-dependent endocytosis and activation in vitro; gain of function and genetic rescue experiments provide strong evidence that these trafficking events are required for Robo repulsive guidance activity in vivo. Our data support a model in which Robo's ligand-dependent internalization from the cell surface to the late endosome is essential for receptor activation and proper repulsive guidance at the midline by allowing recruitment of the downstream effector Son of Sevenless in a spatially constrained endocytic trafficking compartment.
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Affiliation(s)
- Rebecca K. Chance
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Dascenco D, Erfurth ML, Izadifar A, Song M, Sachse S, Bortnick R, Urwyler O, Petrovic M, Ayaz D, He H, Kise Y, Thomas F, Kidd T, Schmucker D. Slit and Receptor Tyrosine Phosphatase 69D Confer Spatial Specificity to Axon Branching via Dscam1. Cell 2015; 162:1140-54. [PMID: 26317474 PMCID: PMC4699798 DOI: 10.1016/j.cell.2015.08.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 06/30/2015] [Accepted: 07/10/2015] [Indexed: 11/26/2022]
Abstract
Axonal branching contributes substantially to neuronal circuit complexity. Studies in Drosophila have shown that loss of Dscam1 receptor diversity can fully block axon branching in mechanosensory neurons. Here we report that cell-autonomous loss of the receptor tyrosine phosphatase 69D (RPTP69D) and loss of midline-localized Slit inhibit formation of specific axon collaterals through modulation of Dscam1 activity. Genetic and biochemical data support a model in which direct binding of Slit to Dscam1 enhances the interaction of Dscam1 with RPTP69D, stimulating Dscam1 dephosphorylation. Single-growth-cone imaging reveals that Slit/RPTP69D are not required for general branch initiation but instead promote the extension of specific axon collaterals. Hence, although regulation of intrinsic Dscam1-Dscam1 isoform interactions is essential for formation of all mechanosensory-axon branches, the local ligand-induced alterations of Dscam1 phosphorylation in distinct growth-cone compartments enable the spatial specificity of axon collateral formation.
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Affiliation(s)
- Dan Dascenco
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Maria-Luise Erfurth
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium; Institute of Biochemistry, Christian-Albrechts-University of Kiel, Olshausenstr. 40, 24098 Kiel, Germany
| | - Azadeh Izadifar
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Minmin Song
- Biology/MS 314, University of Nevada, Reno, NV 89557, USA
| | - Sonja Sachse
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium; Department of Biology, Chemistry & Pharmacy, Free University Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Rachel Bortnick
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Olivier Urwyler
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Milan Petrovic
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Derya Ayaz
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium
| | - Haihuai He
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium
| | - Yoshiaki Kise
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Franziska Thomas
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Thomas Kidd
- Biology/MS 314, University of Nevada, Reno, NV 89557, USA
| | - Dietmar Schmucker
- Neuronal Wiring Laboratory, VIB, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium.
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Comer JD, Pan FC, Willet SG, Haldipur P, Millen KJ, Wright CVE, Kaltschmidt JA. Sensory and spinal inhibitory dorsal midline crossing is independent of Robo3. Front Neural Circuits 2015; 9:36. [PMID: 26257608 PMCID: PMC4511845 DOI: 10.3389/fncir.2015.00036] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 07/02/2015] [Indexed: 11/25/2022] Open
Abstract
Commissural neurons project across the midline at all levels of the central nervous system (CNS), providing bilateral communication critical for the coordination of motor activity and sensory perception. Midline crossing at the spinal ventral midline has been extensively studied and has revealed that multiple developmental lineages contribute to this commissural neuron population. Ventral midline crossing occurs in a manner dependent on Robo3 regulation of Robo/Slit signaling and the ventral commissure is absent in the spinal cord and hindbrain of Robo3 mutants. Midline crossing in the spinal cord is not limited to the ventral midline, however. While prior anatomical studies provide evidence that commissural axons also cross the midline dorsally, little is known of the genetic and molecular properties of dorsally-crossing neurons or of the mechanisms that regulate dorsal midline crossing. In this study, we describe a commissural neuron population that crosses the spinal dorsal midline during the last quarter of embryogenesis in discrete fiber bundles present throughout the rostrocaudal extent of the spinal cord. Using immunohistochemistry, neurotracing, and mouse genetics, we show that this commissural neuron population includes spinal inhibitory neurons and sensory nociceptors. While the floor plate and roof plate are dispensable for dorsal midline crossing, we show that this population depends on Robo/Slit signaling yet crosses the dorsal midline in a Robo3-independent manner. The dorsally-crossing commissural neuron population we describe suggests a substrate circuitry for pain processing in the dorsal spinal cord.
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Affiliation(s)
- John D Comer
- Neuroscience Program, Weill Cornell Graduate School of Medical Sciences New York, NY, USA ; Developmental Biology Program, Sloan-Kettering Institute New York, NY, USA ; Weill Cornell/Rockefeller/Sloan-Kettering Tri-Institutional MD-PhD Program New York, NY, USA
| | - Fong Cheng Pan
- Vanderbilt University Program in Developmental Biology, Department of Cell and Developmental Biology, Vanderbilt Center for Stem Cell Biology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Spencer G Willet
- Vanderbilt University Program in Developmental Biology, Department of Cell and Developmental Biology, Vanderbilt Center for Stem Cell Biology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Parthiv Haldipur
- Seattle Children's Research Institute, Center for Integrative Brain Research Seattle, WA, USA
| | - Kathleen J Millen
- Seattle Children's Research Institute, Center for Integrative Brain Research Seattle, WA, USA ; Department of Pediatrics, Genetics Division, University of Washington Seattle, WA, USA
| | - Christopher V E Wright
- Vanderbilt University Program in Developmental Biology, Department of Cell and Developmental Biology, Vanderbilt Center for Stem Cell Biology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Julia A Kaltschmidt
- Neuroscience Program, Weill Cornell Graduate School of Medical Sciences New York, NY, USA ; Developmental Biology Program, Sloan-Kettering Institute New York, NY, USA
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46
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Zuhdi N, Ortega B, Giovannone D, Ra H, Reyes M, Asención V, McNicoll I, Ma L, de Bellard ME. Slit molecules prevent entrance of trunk neural crest cells in developing gut. Int J Dev Neurosci 2014; 41:8-16. [PMID: 25490618 DOI: 10.1016/j.ijdevneu.2014.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 12/04/2014] [Indexed: 10/24/2022] Open
Abstract
Neural crest cells emerge from the dorsal neural tube early in development and give rise to sensory and sympathetic ganglia, adrenal cells, teeth, melanocytes and especially enteric nervous system. Several inhibitory molecules have been shown to play important roles in neural crest migration, among them are the chemorepulsive Slit1-3. It was known that Slits chemorepellants are expressed at the entry to the gut, and thus could play a role in the differential ability of vagal but not trunk neural crest cells to invade the gut and form enteric ganglia. Especially since trunk neural crest cells express Robo receptor while vagal do not. Thus, although we know that Robo mediates migration along the dorsal pathway in neural crest cells, we do not know if it is responsible in preventing their entry into the gut. The goal of this study was to further corroborate a role for Slit molecules in keeping trunk neural crest cells away from the gut. We observed that when we silenced Robo receptor in trunk neural crest, the sympathoadrenal (somites 18-24) were capable of invading gut mesenchyme in larger proportion than more rostral counterparts. The more rostral trunk neural crest tended not to migrate beyond the ventral aorta, suggesting that there are other repulsive molecules keeping them away from the gut. Interestingly, we also found that when we silenced Robo in sacral neural crest they did not wait for the arrival of vagal crest but entered the gut and migrated rostrally, suggesting that Slit molecules are the ones responsible for keeping them waiting at the hindgut mesenchyme. These combined results confirm that Slit molecules are responsible for keeping the timeliness of colonization of the gut by neural crest cells.
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Affiliation(s)
- Nora Zuhdi
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Blanca Ortega
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Dion Giovannone
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Hannah Ra
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Michelle Reyes
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Viviana Asención
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Ian McNicoll
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA
| | - Le Ma
- Department of Neuroscience, Thomas Jefferson University, BLSB 306, Philadelphia, PA 19107, USA
| | - Maria Elena de Bellard
- California State University Northridge, Biology Deptartment, MC 8303. 18111 Nordhoff Street. Northridge, CA 91330, USA.
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Blockus H, Chédotal A. The multifaceted roles of Slits and Robos in cortical circuits: from proliferation to axon guidance and neurological diseases. Curr Opin Neurobiol 2014; 27:82-8. [PMID: 24698714 DOI: 10.1016/j.conb.2014.03.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/17/2014] [Accepted: 03/09/2014] [Indexed: 11/20/2022]
Abstract
Slit repulsion, mediated by Robo receptors, is known to play a major role in axon guidance in the nervous system. However, recent studies have revealed that in the mammalian cortex these molecules are highly versatile and that their function extends far beyond axon guidance. They act at all phases of development to control neurogenesis, neuronal migration, axon patterning, dendritic outgrowth and spinogenesis. The expression of Robo receptors in cortical and thalamocortical axons (TCAs) is tightly regulated by a combination of transcription factors (TFs), proteases and activity. These findings also suggest that Slit and Robos have influenced the evolution of cortical circuits. Last, novel genetic evidence associates various neurological disorders, such as autism, to abnormal Slit/Robo signaling.
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Affiliation(s)
- Heike Blockus
- INSERM UMR_S968, Institut de la Vision, F-75012 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR_S968, Institut de la vision, F-75012, France; CNRS, UMR7210, F-75012 Paris, France
| | - Alain Chédotal
- INSERM UMR_S968, Institut de la Vision, F-75012 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR_S968, Institut de la vision, F-75012, France; CNRS, UMR7210, F-75012 Paris, France.
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48
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Gibson DA, Tymanskyj S, Yuan RC, Leung HC, Lefebvre JL, Sanes JR, Chédotal A, Ma L. Dendrite self-avoidance requires cell-autonomous slit/robo signaling in cerebellar purkinje cells. Neuron 2014; 81:1040-1056. [PMID: 24607227 DOI: 10.1016/j.neuron.2014.01.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2013] [Indexed: 10/25/2022]
Abstract
Dendrites from the same neuron usually develop nonoverlapping patterns by self-avoidance, a process requiring contact-dependent recognition and repulsion. Recent studies have implicated homophilic interactions of cell surface molecules, including Dscams and Pcdhgs, in self-recognition, but repulsive molecular mechanisms remain obscure. Here, we report a role for the secreted molecule Slit2 and its receptor Robo2 in self-avoidance of cerebellar Purkinje cells (PCs). Both molecules are highly expressed by PCs, and their deletion leads to excessive dendrite self-crossing without affecting arbor size and shape. This cell-autonomous function is supported by the boundary-establishing activity of Slit in culture and the phenotype rescue by membrane-associated Slit2 activities. Furthermore, genetic studies show that they act independently from Pcdhg-mediated recognition. Finally, PC-specific deletion of Robo2 is associated with motor behavior alterations. Thus, our study uncovers a local repulsive mechanism required for self-avoidance and demonstrates the molecular complexity at the cell surface in dendritic patterning.
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Affiliation(s)
- Daniel A Gibson
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Stephen Tymanskyj
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Rachel C Yuan
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Haiwen C Leung
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Julie L Lefebvre
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Alain Chédotal
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMR_S968, CNRS_UMR7210, Institut de la Vision, 750012, Paris, France
| | - Le Ma
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
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49
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The effect of substrate topography on direct reprogramming of fibroblasts to induced neurons. Biomaterials 2014; 35:5327-5336. [PMID: 24709523 DOI: 10.1016/j.biomaterials.2014.03.034] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 03/14/2014] [Indexed: 11/23/2022]
Abstract
Cellular reprogramming holds tremendous potential for cell therapy and regenerative medicine. Recently, fibroblasts have been directly converted into induced neurons (iNs) by overexpression of the neuronal transcription factors Ascl1, Brn2 and Myt1L. Hypothesizing that cell-topography interactions could influence the fibroblast-to-neuron reprogramming process, we investigated the effects of various topographies on iNs produced by direct reprogramming. Final iN purity and conversion efficiency were increased on micrograting substrates. Neurite branching was increased on microposts and decreased on microgratings, with a simplified dendritic arbor characterized by the reduction of MAP2(+) neurites. Neurite outgrowth increased significantly on various topographies. DNA microarray analysis detected 20 differentially expressed genes in iNs reprogrammed on smooth versus microgratings, and quantitative PCR (qPCR) confirmed the upregulation of Vip and downregulation of Thy1 and Bmp5 on microgratings. Electrophysiology and calcium imaging verified the functionality of these iNs. This study demonstrates the potential of applying topographical cues to optimize cellular reprogramming.
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50
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Nogo receptor homolog NgR2 expressed in sensory DRG neurons controls epidermal innervation by interaction with Versican. J Neurosci 2014; 34:1633-46. [PMID: 24478347 DOI: 10.1523/jneurosci.3094-13.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Primary sensory afferents of the dorsal root ganglion (DRG) that innervate the skin detect a wide range of stimuli, such as touch, temperature, pain, and itch. Different functional classes of nociceptors project their axons to distinct target zones within the developing skin, but the molecular mechanisms that regulate target innervation are less clear. Here we report that the Nogo66 receptor homolog NgR2 is essential for proper cutaneous innervation. NgR2(-/-) mice display increased density of nonpeptidergic nociceptors in the footpad and exhibit enhanced sensitivity to mechanical force and innocuous cold temperatures. These sensory deficits are not associated with any abnormality in morphology or density of DRG neurons. However, deletion of NgR2 renders nociceptive nonpeptidergic sensory neurons insensitive to the outgrowth repulsive activity of skin-derived Versican. Biochemical evidence shows that NgR2 specifically interacts with the G3 domain of Versican. The data suggest that Versican/NgR2 signaling at the dermo-epidermal junction acts in vivo as a local suppressor of axonal plasticity to control proper density of epidermal sensory fiber innervation. Our findings not only reveal the existence of a novel and unsuspected mechanism regulating epidermal target innervation, but also provide the first evidence for a physiological role of NgR2 in the peripheral nervous system.
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