Cortical interneurons as a population are recognized to be remarkably diverse in terms of their morphology, connectivity and physiological properties. In recent years numerous investigators have focused on understanding how this diversity is generated. In the previous funding cycle of this grant we were able to demonstrate that the place and time of origin of different cortical interneuron populations predicts their mature properties (Butt et al., 2005). In particular we found that the medial and caudal ganglionic eminences (MGE and CGE, respectively), while together accounting for the vast majority of cortical interneurons, produce entirely non-overlapping cohorts. In an effort to understand the developmental genetic mechanisms by which different cortical interneuron populations arise from these structures, we undertook a conditional loss of function analysis of the homeobox-containing gene Nkx2-1, which at present is the only gene that precisely distinguishes between the MGE and CGE (Butt et al., 2008). This study revealed that Nkx2-1 acts as a molecular toggle switch that promotes the generation of MGE-derived cortical interneuron populations and represses the CGE-derived interneuron cell identities. In this grant we will explore the genes that are both positively and negatively regulated by Nkx2-1 gene function. First we will undertake a structure function analysis of Nkx2-1 to examine its ability to act as a transcriptional activator and repressor. We will follow this by exploring the contribution of genes that are activated by Nkx2-1 and evaluate their contributions to the production of cortical interneurons with specific subtype character. Finally we will use a genetic approach to explore the diversity and timing of CGE-derived interneuron generation and how CoupTF1 and CoupTF2, CGE-expressed genes with complementary expression to Nkx2-1, contribute to the generation of the interneuron subtypes derived from this structure. Together, this study will provide insights into the molecular basis by which cortical interneuron subtypes are generated. Increasingly it is being recognized that cortical interneurons through their maintenance of the excitatory/inhibitory balance in the CNS are central to the normal function of the nervous system. In addition, cortical interneurons have been implicated in neurological disorders including epilepsy, bipolar disorders and autism. Our proposal by exploring the genetic mechanisms by which these cell types are generated has the potential to ultimately provide tools for targeting and manipulating this critical population.

Public Health Relevance

In this proposal, we use developmental genetic approaches to explore the programs that lead to the generation of specific cortical interneuron subtypes. We expect that through deciphering the genetic logic by which these cells are formed, we will be able to develop methods for cortical interneuron replacement strategies and for biochemical investigations leading to drug discovery. Moreover, through the genetic profiling of these cells we expect to be able to directly link the function of these cells to specific genetically inherited disorders in human patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
3R01MH071679-09S1
Application #
8721099
Study Section
Neurogenesis and Cell Fate Study Section (NCF)
Program Officer
Panchision, David M
Project Start
2013-09-23
Project End
2015-08-31
Budget Start
2013-09-23
Budget End
2015-08-31
Support Year
9
Fiscal Year
2013
Total Cost
$472,825
Indirect Cost
$193,872
Name
New York University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
121911077
City
New York
State
NY
Country
United States
Zip Code
10016
Kepecs, Adam; Fishell, Gordon (2014) Interneuron cell types are fit to function. Nature 505:318-26
De Marco Garcia, Natalia V; Fishell, Gord (2014) Subtype-selective electroporation of cortical interneurons. J Vis Exp :e51518
Cassataro, Daniela; Bergfeldt, Daniella; Malekian, Cariz et al. (2014) Reverse pharmacogenetic modulation of the nucleus accumbens reduces ethanol consumption in a limited access paradigm. Neuropsychopharmacology 39:283-90
Takada, Naoki; Pi, Hyun Jae; Sousa, Vitor H et al. (2014) A developmental cell-type switch in cortical interneurons leads to a selective defect in cortical oscillations. Nat Commun 5:5333
Karayannis, T; Au, E; Patel, J C et al. (2014) Cntnap4 differentially contributes to GABAergic and dopaminergic synaptic transmission. Nature 511:236-40
Kang, Wenfei; Balordi, Francesca; Su, Nan et al. (2014) Astrocyte activation is suppressed in both normal and injured brain by FGF signaling. Proc Natl Acad Sci U S A 111:E2987-95
Fishell, Gord; Heintz, Nathaniel (2013) The neuron identity problem: form meets function. Neuron 80:602-12
Rossignol, Elsa; Kruglikov, Illya; van den Maagdenberg, Arn M J M et al. (2013) CaV 2.1 ablation in cortical interneurons selectively impairs fast-spiking basket cells and causes generalized seizures. Ann Neurol 74:209-22
Lee, Soohyun; Kruglikov, Illya; Huang, Z Josh et al. (2013) A disinhibitory circuit mediates motor integration in the somatosensory cortex. Nat Neurosci 16:1662-70
Miyoshi, Goichi; Fishell, Gord (2011) GABAergic interneuron lineages selectively sort into specific cortical layers during early postnatal development. Cereb Cortex 21:845-52

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