title: Expression of the protein chaperone, clusterin, in spinal cord cells constitutively and following cellular stress, and upregulation by treatment with Hsp90 inhibitor.
abstract: Clusterin, a protein chaperone found at high levels in physiological fluids, is expressed in nervous tissue and upregulated in several neurological diseases. To assess relevance to amyotrophic lateral sclerosis (ALS) and other motor neuron disorders, clusterin expression was evaluated using long-term dissociated cultures of murine spinal cord and SOD1(G93A) transgenic mice, a model of familial ALS. Motor neurons and astrocytes constitutively expressed nuclear and cytoplasmic forms of clusterin, and secreted clusterin accumulated in culture media. Although clusterin can be stress inducible, heat shock failed to increase levels in these neural cell compartments despite robust upregulation of stress-inducible Hsp70 (HspA1) in non-neuronal cells. In common with HSPs, clusterin was upregulated by treatment with the Hsp90 inhibitor, geldanamycin, and thus could contribute to the neuroprotection previously identified for such compounds in disease models. Clusterin expression was not altered in cultured motor neurons expressing SOD1(G93A) by gene transfer or in presymptomatic SOD1(G93A) transgenic mice; however, clusterin immunolabeling was weakly increased in lumbar spinal cord of overtly symptomatic mice. More striking, mutant SOD1 inclusions, a pathological hallmark, were strongly labeled by anti-clusterin. Since secreted, as well as intracellular, mutant SOD1 contributes to toxicity, the extracellular chaperoning property of clusterin could be important for folding and clearance of SOD1 and other misfolded proteins in the extracellular space. Evaluation of chaperone-based therapies should include evaluation of clusterin as well as HSPs, using experimental models that replicate the control mechanisms operant in the cells and tissue of interest.
authors.affiliation: Montreal Neurological Institute and Department of Neurology/Neurosurgery, McGill University, 3801 University St., Montreal, QC, Canada, H3A 2B4.
authors.forename: Samantha
authors.initials: S
authors.lastname: Zinkie
authors.forename: Benoit J
authors.initials: BJ
authors.lastname: Gentil
authors.forename: Sandra
authors.initials: S
authors.lastname: Minotti
authors.forename: Heather D
authors.initials: HD
authors.lastname: Durham
mesh_terms: D019943:Amino Acid Substitution; D000690:Amyotrophic Lateral Sclerosis / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D016227:Benzoquinones / Q000494:pharmacology*; D002478:Cells, Cultured; D051152:Clusterin / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000166:cytology / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D013696:Temperature; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D016227:Benzoquinones; D051152:Clusterin; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; C001277:geldanamycin