title: Heterogeneity of subcellular localization and electrophoretic mobility of survival motor neuron (SMN) protein in mammalian neural cells and tissues.
abstract: Spinal muscular atrophy is caused by defects in the survival motor neuron (SMN) gene. To better understand the patterns of expression of SMN in neuronal cells and tissues, we raised a polyclonal antibody (abSMN) against a synthetic oligopeptide from SMN exon 2. AbSMN immunostaining in neuroblastoma cells and mouse and human central nervous system (CNS) showed intense labeling of nuclear "gems," along with prominent nucleolar immunoreactivity in mouse and human CNS tissues. Strong cytoplasmic labeling was observed in the perikarya and proximal dendrites of human spinal motor neurons but not in their axons. Immunoblot analysis revealed a 34-kDa species in the insoluble protein fractions from human SY5Y neuroblastoma cells, embryonic mouse spinal cord cultures, and human CNS tissue. By contrast, a 38-kDa species was detected in the cytosolic fraction of SY5Y cells. We conclude that SMN protein is expressed prominently in both the cytoplasm and nucleus in multiple types of neurons in brain and spinal cord, a finding consistent with a role for SMN as a determinant of neuronal viability.
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Francis
authors.forename: A W
authors.initials: AW
authors.lastname: Sandrock
authors.forename: P G
authors.initials: PG
authors.lastname: Bhide
authors.forename: J P
authors.initials: JP
authors.lastname: Vonsattel
authors.forename: R H
authors.initials: RH
authors.lastname: Brown
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D002490:Central Nervous System / Q000378:metabolism* / Q000473:pathology; D017362:Cyclic AMP Response Element-Binding Protein; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D009134:Muscular Atrophy, Spinal / Q000378:metabolism* / Q000473:pathology*; D009419:Nerve Tissue Proteins / Q000032:analysis*; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins