title: Heparan sulfate regulates intraretinal axon pathfinding by retinal ganglion cells.
abstract: PURPOSE. Heparan sulfate (HS) is abundantly expressed in the developing neural retina; however, its role in the intraretinal axon guidance of retinal ganglion cells (RGCs) remains unclear. In this study, the authors examined whether HS was essential for the axon guidance of RGCs toward the optic nerve head. METHODS. The authors conditionally ablated the gene encoding the exostosin-1 (Ext1) enzyme, using the dickkopf homolog 3 (Dkk3)-Cre transgene, which disrupted HS expression in the mouse retina during directed pathfinding by RGC axons toward the optic nerve head. In situ hybridization, immunohistochemistry, DiI tracing, binding assay, and retinal explant assays were performed to evaluate the phenotypes of the mutants and the roles of HS in intraretinal axon guidance. RESULTS. Despite no gross abnormality in RGC distribution, the mutant RGC axons exhibited severe intraretinal guidance errors, including optic nerve hypoplasia, ectopic axon penetration through the full thickness of the neural retina and into the subretinal space, and disturbance of the centrifugal projection of RGC axons toward the optic nerve head. These abnormal phenotypes shared similarities with the RGC axon misguidance caused by mutations of genes encoding Netrin-1 and Slit-1/2. Explant assays revealed that the mutant RGCs exhibited disturbed Netrin-1-dependent axon outgrowth and Slit-2-dependent repulsion. CONCLUSIONS. The present study demonstrated that RGC axon projection toward the optic nerve head requires the expression of HS in the neural retina, suggesting that HS in the retina functions as an essential modulator of Netrin-1 and Slit-mediated intraretinal RGC axon guidance.
authors: Department of Ophthalmology and Visual Science, Kumamoto University Graduate School of Medical Sciences, Japan.
authors: Minako
authors: M
authors: Ogata-Iwao
authors: Masaru
authors: M
authors: Inatani
authors: Keiichiro
authors: K
authors: Iwao
authors: Yuji
authors: Y
authors: Takihara
authors: Yuko
authors: Y
authors: Nakaishi-Fukuchi
authors: Fumitoshi
authors: F
authors: Irie
authors: Shigeru
authors: S
authors: Sato
authors: Takahisa
authors: T
authors: Furukawa
authors: Yu
authors: Y
authors: Yamaguchi
authors: Hidenobu
authors: H
authors: Tanihara
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005124:Eye Abnormalities / Q000503:physiopathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006497:Heparan Sulfate / Q000502:physiology*; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D000075388:Netrin-1; D009431:Neural Conduction / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D009898:Optic Disk / Q000002:abnormalities / Q000196:embryology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012160:Retina / Q000196:embryology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D014795:Visual Pathways; D000099058:Exostosin 1; D000098552:Slit Homolog 2 Protein
chemical_list: D006497:Heparan Sulfate; D036341:Intercellular Signaling Peptides and Proteins; D017351:N-Acetylglucosaminyltransferases; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D000075388:Netrin-1; D025521:Tumor Suppressor Proteins; D000099058:Exostosin 1; D000098552:Slit Homolog 2 Protein; C000617353:Ntn1 protein, mouse; C120010:Slit1 protein, mouse