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Differential gene expression in the axotomized facial motor nucleus of presymptomatic SOD1 mice

Authors

  • Nichole A. Mesnard,

    Corresponding author
    1. Neuroscience Program, Loyola University Medical Center, Maywood, Illinois, 60153
    2. Research and Development Service, Hines Veterans Administration Hospital, Hines, Illinois 60141
    3. Department of Microbiology and Immunology, Loyola University Medical Center, Maywood, Illinois 60153
    • Edward J. Hines VA Hospital, 5000 South 5th Ave., Bldg. 1, Rm. A225, Hines, IL 60141-3030
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  • Virginia M. Sanders,

    1. Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University, Columbus, Ohio 43210
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    • The last two authors share senior authorship.

  • Kathryn J. Jones

    1. Research and Development Service, Hines Veterans Administration Hospital, Hines, Illinois 60141
    2. Department of Microbiology and Immunology, Loyola University Medical Center, Maywood, Illinois 60153
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    • The last two authors share senior authorship.


Abstract

Previously, we compared molecular profiles of one population of wild-type (WT) mouse facial motoneurons (FMNs) surviving with FMNs undergoing significant cell death after axotomy. Regardless of their ultimate fate, injured FMNs respond with a vigorous pro-survival/regenerative molecular response. In contrast, the neuropil surrounding the two different injured FMN populations contained distinct molecular differences that support a causative role for glial and/or immune-derived molecules in directing contrasting responses of the same cell types to the same injury. In the current investigation, we utilized the facial nerve axotomy model and a presymptomatic amyotrophic lateral sclerosis (ALS) mouse (SOD1) model to experimentally mimic the axonal die-back process observed in ALS pathogenesis without the confounding variable of disease onset. Presymptomatic SOD1 mice had a significant decrease in FMN survival compared with WT, which suggests an increased susceptibility to axotomy. Laser microdissection was used to accurately collect uninjured and axotomized facial motor nuclei of WT and presymptomatic SOD1 mice for mRNA expression pattern analyses of pro-survival/pro-regeneration genes, neuropil-specific genes, and genes involved in or responsive to the interaction of FMNs and non-neuronal cells. Axotomized presymptomatic SOD1 FMNs displayed a dynamic pro-survival/regenerative response to axotomy, similar to WT, despite increased cell death. However, significant differences were revealed when the axotomy-induced gene expression response of presymptomatic SOD1 neuropil was compared with WT. We propose that the increased susceptibility of presymptomatic SOD1 FMNs to axotomy-induced cell death and, by extrapolation, disease progression, is not intrinsic to the motoneuron, but rather involves a dysregulated response by non-neuronal cells in the surrounding neuropil. J. Comp. Neurol. 519:3488–3506, 2011. © 2011 Wiley-Liss, Inc.

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