title: Cortical interneurons require Jnk1 to enter and navigate the developing cerebral cortex.
abstract: Proper assembly of cortical circuitry relies on the correct migration of cortical interneurons from their place of birth in the ganglionic eminences to their place of terminal differentiation in the cerebral cortex. Although molecular mechanisms mediating cortical interneuron migration have been well studied, intracellular signals directing their migration are largely unknown. Here we illustrate a novel and essential role for c-Jun N-terminal kinase (JNK) signaling in guiding the pioneering population of cortical interneurons into the mouse cerebral cortex. Migrating cortical interneurons express Jnk proteins at the entrance to the cortical rudiment and have enriched expression of Jnk1 relative to noninterneuronal cortical cells. Pharmacological blockade of JNK signaling in ex vivo slice cultures resulted in dose-dependent and highly specific disruption of interneuron migration into the nascent cortex. Time-lapse imaging revealed that JNK-inhibited cortical interneurons advanced slowly and assumed aberrant migratory trajectories while traversing the cortical entry zone. In vivo analyses of JNK-deficient embryos supported our ex vivo pharmacological data. Deficits in interneuron migration were observed in Jnk1 but not Jnk2 single nulls, and those migratory deficits were further exacerbated when homozygous loss of Jnk1 was combined with heterozygous reduction of Jnk2. Finally, genetic ablation of Jnk1 and Jnk2 from cortical interneurons significantly perturbed migration in vivo, but not in vitro, suggesting JNK activity functions to direct their guidance rather than enhance their motility. These data suggest JNK signaling, predominantly mediated by interneuron expressed Jnk1, is required for guiding migration of cortical interneurons into and within the developing cerebral cortex.
authors.affiliation: Department of Neurobiology and Anatomy, Neuroscience Graduate Program, and Center for Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia 26506, and.
authors.forename: Abigail K
authors.initials: AK
authors.lastname: Myers
authors.affiliation: Department of Pharmacology and Physiology, The George Washington University Medical Center, Washington, DC 20037.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Meechan
authors.affiliation: Department of Neurobiology and Anatomy, Center for Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia 26506, and.
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Adney
authors.affiliation: Department of Neurobiology and Anatomy, Center for Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia 26506, and etucker@hsc.wvu.edu.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Tucker
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology* / Q000254:growth & development; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007395:Interneurons / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D048055:Mitogen-Activated Protein Kinase 8 / Q000235:genetics / Q000378:metabolism*; D048056:Mitogen-Activated Protein Kinase 9 / Q000235:genetics / Q000378:metabolism; D009924:Organ Culture Techniques; D011247:Pregnancy; D013997:Time Factors
chemical_list: C501120:Dlx5 protein, mouse; C100597:Dlx6 protein, mouse; D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D048056:Mitogen-Activated Protein Kinase 9; D048055:Mitogen-Activated Protein Kinase 8
keywords: GABAergic interneuron; development; forebrain; intracellular signaling; neuronal migration; psychiatric disorder