Type A GABA-receptor-dependent synaptic transmission sculpts dendritic arbor structure in Xenopus tadpoles in vivo.

Shen, W., Da Silva, J. S., He, H., Cline, H. T. (April 2009) Type A GABA-receptor-dependent synaptic transmission sculpts dendritic arbor structure in Xenopus tadpoles in vivo. J Neurosci, 29 (15). pp. 5032-43. ISSN 0270-6474 (Print)1529-2401 (Electronic)

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Abstract

The emergence of dendritic arbor structure in vivo depends on synaptic inputs. We tested whether inhibitory GABAergic synaptic transmission regulates Xenopus optic tectal cell dendritic arbor development in vivo by expressing a peptide corresponding to an intracellular loop (ICL) of the γ2 subunit of GABAAR which is required to anchor GABAA receptors to the postsynaptic scaffold. GFP-tagged ICL (EGFP-ICL) was distributed in a punctate pattern at putative inhibitory synapses, identified by VGAT-immunoreactive puncta. ICL expression completely blocked GABAAR - mediated transmission in 36% of transfected neurons and significantly reduced GABAAR - mediated synaptic currents relative to AMPAR-mediated synaptic currents in the remaining transfected neurons without altering release probability or neuronal excitability. Further analysis of ICL-expressing neurons with residual GABAAR- mediated inputs showed that the capacity of benzodiazepine to enhance GABAergic synaptic responses was reduced in ICL-expressing neurons, indicating that they were likely depleted of γ2 subunit-containing GABAAR. Neurons expressing a mutant form of ICL were comparable to controls. In vivo time-lapse images showed that ICL-expressing neurons have more sparsely branched dendritic arbors which expand over larger neuropil areas than EGFP-expressing control neurons. Analysis of branch dynamics indicated that ICL expression affected arbor growth by reducing rates of branch addition. Furthermore, we found that decreasing GABAergic synaptic transmission with ICL expression blocked visual experience dependent dendritic arbor structural plasticity. Our findings establish an essential role for inhibitory GABAergic synaptic transmission in the regulation of dendritic structural plasticity in Xenopus in vivo.

Item Type:	Paper
Subjects:	bioinformatics > genomics and proteomics > small molecules > GABA bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification organism description > animal organs, tissues, organelles, cell types and functions > cell types and functions > cell functions organs, tissues, organelles, cell types and functions > cell types and functions organs, tissues, organelles, cell types and functions bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein receptor organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > synaptic transmission organism description > animal > Frog > xenopus
CSHL Authors:	Cline, Hollis T. Da Silva, Jorge S. He, Haiyan Shen, Wanhua
Communities:	CSHL labs > Cline lab
Depositing User:	Matt Covey
Date:	15 April 2009
Date Deposited:	15 Feb 2013 20:46
Last Modified:	15 Feb 2013 20:46
PMCID:	PMC2706946
Related URLs:	Publisher
URI:	https://repository.cshl.edu/id/eprint/27474

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