The Journal of Neuroscience, October 28, 2009, 29(43):13672-13683; doi:10.1523/JNEUROSCI.2127-09.2009
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Development/Plasticity/Repair
Differential Gene Expression in the Developing Lateral Geniculate Nucleus and Medial Geniculate Nucleus Reveals Novel Roles for Zic4 and Foxp2 in Visual and Auditory Pathway Development
Sam Horng,1,2
Gabriel Kreiman,3
Charlene Ellsworth,1,2
Damon Page,1,2
Marissa Blank,4
Kathleen Millen,4 and
Mriganka Sur1,2
1Department of Brain and Cognitive Sciences and 2Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, 3Department of Ophthalmology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, and 4Department of Human Genetics, University of Chicago, Chicago, Illinois 60637
Correspondence should be addressed to Mriganka Sur, 32 Vassar Street, 46-6237 Cambridge, MA 02139. Email: msur{at}mit.edu
Primary sensory nuclei of the thalamus process and relay parallel channels of sensory input into the cortex. The developmental processes by which these nuclei acquire distinct functional roles are not well understood. To identify novel groups of genes with a potential role in differentiating two adjacent sensory nuclei, we performed a microarray screen comparing perinatal gene expression in the principal auditory relay nucleus, the medial geniculate nucleus (MGN), and principal visual relay nucleus, the lateral geniculate nucleus (LGN). We discovered and confirmed groups of highly ranked, differentially expressed genes with qRT-PCR and in situ hybridization. A functional role for Zic4, a transcription factor highly enriched in the LGN, was investigated using Zic4-null mice, which were found to have changes in topographic patterning of retinogeniculate projections. Foxp2, a transcriptional repressor expressed strongly in the MGN, was found to be positively regulated by activity in the MGN. These findings identify roles for two differentially expressed genes, Zic4 and Foxp2, in visual and auditory pathway development. Finally, to test whether modality-specific patterns of gene expression are influenced by extrinsic patterns of input, we performed an additional microarray screen comparing the normal MGN to "rewired" MGN, in which normal auditory afferents are ablated and novel retinal inputs innervate the MGN. Data from this screen indicate that rewired MGN acquires some patterns of gene expression that are present in the developing LGN, including an upregulation of Zic4 expression, as well as novel patterns of expression which may represent unique processes of cross-modal plasticity.
Received May 5, 2009;
revised Aug. 29, 2009;
accepted Sept. 3, 2009.
Correspondence should be addressed to Mriganka Sur, 32 Vassar Street, 46-6237 Cambridge, MA 02139. Email: msur{at}mit.edu