title: Expansion of the piriform cortex contributes to corticothalamic pathfinding defects in Gli3 conditional mutants.
abstract: The corticothalamic and thalamocortical tracts play essential roles in the communication between the cortex and thalamus. During development, axons forming these tracts have to follow a complex path to reach their target areas. While much attention has been paid to the mechanisms regulating their passage through the ventral telencephalon, very little is known about how the developing cortex contributes to corticothalamic/thalamocortical tract formation. Gli3 encodes a zinc finger transcription factor widely expressed in telencephalic progenitors which has important roles in corticothalamic and thalamocortical pathfinding. Here, we conditionally inactivated Gli3 in dorsal telencephalic progenitors to determine its role in corticothalamic tract formation. In Emx1Cre;Gli3(fl/fl) mutants, only a few corticothalamic axons enter the striatum in a restricted dorsal domain. This restricted entry correlates with a medial expansion of the piriform cortex. Transplantation experiments showed that the expanded piriform cortex repels corticofugal axons. Moreover, expression of Sema5B, a chemorepellent for corticofugal axons produced by the piriform cortex, is similarly expanded. Finally, time course analysis revealed an expansion of the ventral pallial progenitor domain which gives rise to the piriform cortex. Hence, control of lateral cortical development by Gli3 at the progenitor level is crucial for corticothalamic pathfinding.
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: Eleni-Maria
authors.initials: EM
authors.lastname: Amaniti
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: Chaoying
authors.initials: C
authors.lastname: Fu
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: Sean
authors.initials: S
authors.lastname: Lewis
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: Marina
authors.initials: M
authors.lastname: Saisana
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: Dario
authors.initials: D
authors.lastname: Magnani
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: John O
authors.initials: JO
authors.lastname: Mason
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Theil
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology / Q000502:physiology*; D003342:Corpus Striatum / Q000196:embryology / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D008822:Mice, Transgenic; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009434:Neural Pathways / Q000196:embryology / Q000473:pathology / Q000503:physiopathology; D066195:Piriform Cortex / Q000196:embryology* / Q000473:pathology / Q000503:physiopathology*; D039961:Semaphorins / Q000378:metabolism; D013788:Thalamus / Q000196:embryology* / Q000473:pathology / Q000503:physiopathology*; D046509:Tissue Culture Techniques; D000074290:Zinc Finger Protein Gli3
chemical_list: C465571:Gli3 protein, mouse; D051741:Kruppel-Like Transcription Factors; D009419:Nerve Tissue Proteins; D039961:Semaphorins; D000074290:Zinc Finger Protein Gli3
keywords: Gli3; corticothalamic tract; piriform cortex; sema5b