Localization of myocyte enhancer factor 2 in the rodent forebrain: regionally-specific cytoplasmic expression of MEF2A.

Neely MD, Robert EM, Baucum AJ, Colbran RJ, Muly EC, Deutch AY
Brain Res. 2009 1274: 55-65

PMID: 19362076 · PMCID: PMC2723059 · DOI:10.1016/j.brainres.2009.03.067

The transcription factor myocyte enhancer factor 2 (MEF2) is expressed throughout the central nervous system, where four MEF2 isoforms play important roles in neuronal survival and differentiation and in synapse formation and maintenance. It is therefore somewhat surprising that there is a lack of detailed information on the localization of MEF2 isoforms in the mammalian brain. We have analyzed the regional, cellular, and subcellular expression of MEF2A and MEF2D in the rodent brain. These two MEF2 isoforms were co-expressed in virtually all neurons in the cortex and the striatum, but were not detected in astrocytes. MEF2A and MEF2D were localized to the nuclei of neurons in many forebrain areas, consistent with their roles as transcriptional regulators. However, in several subcortical sites we observed extensive cytoplasmic expression of MEF2A but not MEF2D. MEF2A was particularly enriched in processes of neurons in the lateral septum and bed nucleus of the stria terminalis, as well as in several other limbic sites, including the central amygdala and paraventricular nuclei of the hypothalamus and thalamus. Ultrastructural examination similarly revealed MEF2A-ir in axons and dendrites as well as MEF2A-ir nuclei in the lateral septum and bed nucleus of the stria terminalis neurons. This study demonstrates for the first time extensive cytoplasmic localization of a MEF2 transcription factor in the mammalian brain in vivo. The extranuclear localization of MEF2A suggests novel roles for MEF2A in specific neuronal populations.

MeSH Terms (15)

Animals Blotting, Western Cell Nucleus Cytoplasm Immunohistochemistry MADS Domain Proteins Male MEF2 Transcription Factors Microscopy, Electron, Transmission Myogenic Regulatory Factors Neurons Prosencephalon Protein Isoforms Rats Rats, Sprague-Dawley

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