title: A molecular mechanism regulating the timing of corticogeniculate innervation.
abstract: Neural circuit formation demands precise timing of innervation by different classes of axons. However, the mechanisms underlying such activity remain largely unknown. In the dorsal lateral geniculate nucleus (dLGN), axons from the retina and visual cortex innervate thalamic relay neurons in a highly coordinated manner, with those from the cortex arriving well after those from retina. The differential timing of retino- and corticogeniculate innervation is not a coincidence but is orchestrated by retinal inputs. Here, we identified a chondroitin sulfate proteoglycan (CSPG) that regulates the timing of corticogeniculate innervation. Aggrecan, a repulsive CSPG, is enriched in neonatal dLGN and inhibits cortical axons from prematurely entering the dLGN. Postnatal loss of aggrecan from dLGN coincides with upregulation of aggrecanase expression in the dLGN and corticogeniculate innervation and, it is important to note, is regulated by retinal inputs. Taken together, these studies reveal a molecular mechanism through which one class of axons coordinates the temporal targeting of another class of axons.
authors.affiliation: Virginia Tech Carilion Research Institute, Roanoke, VA 24016, USA; Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, USA.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Brooks
authors.forename: Jianmin
authors.initials: J
authors.lastname: Su
authors.forename: Carl
authors.initials: C
authors.lastname: Levy
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Wang
authors.forename: Tania A
authors.initials: TA
authors.lastname: Seabrook
authors.forename: William
authors.initials: W
authors.lastname: Guido
authors.forename: Michael A
authors.initials: MA
authors.lastname: Fox
mesh_terms: D053674:Aggrecans / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000502:physiology; D005829:Geniculate Bodies / Q000502:physiology*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000502:physiology; D009474:Neurons / Q000502:physiology; D012160:Retina / Q000502:physiology; D015854:Up-Regulation; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology
chemical_list: D053674:Aggrecans; D009419:Nerve Tissue Proteins