title: Metallothionein-3 is a component of a multiprotein complex in the mouse brain.
abstract: Metallothionein (MT)-3, originally called growth inhibitory factor (GIF), was initially identified through its ability to inhibit the growth of neuronal cells in the presence of brain extract. MT-3 is the brain specific isoform of the MT family whose specific biological activity associates it with neurological disorders. Indeed, studies report that MT-3 is decreased by ~30% in brains of patients with Alzheimer disease (AD). Furthermore, many lines of evidence suggest that MT-3 engages in specific protein interactions. To address this, we conducted immunoaffinity chromatography experiments using an immobilized anti-mouse MT-3 antibody. We identified five associated proteins from the pool of sixteen recovered using mass spectrometry and tandem mass spectrometry after in-gel trypsin digestion of bands from the affinity chromatography. The proteins identified were: heat shock protein 84 (HSP84), heat shock protein 70 (HSP70), dihydropyrimidinase-like protein-2 (DRP-2), creatine kinase (CK) and beta-actin. Coimmunoprecipitation experiments, also conducted on whole mouse brain extract using the anti-mouse MT-3 antibody along with commercially available antibodies against HSP84 and CK, confirmed that these three proteins were in a single protein complex. Immunohistochemical experiments were then conducted on the perfused mouse brain that confirmed the in situ colocalization of CK and MT-3 in the hippocampus region. These data provide new insights into the involvement of MT-3 in a multiprotein complex, which will be used to understand the biological activity of MT-3 and its role in neurological disease.
authors.affiliation: Department of Biochemistry, Molecular Biology, and Biophysics, 6-155 Jackson Hall, 321 Church Street, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: I
authors.initials: I
authors.lastname: El Ghazi
authors.forename: B L
authors.initials: BL
authors.lastname: Martin
authors.forename: I M
authors.initials: IM
authors.lastname: Armitage
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D007150:Immunohistochemistry; D000090023:Metallothionein 3; D051379:Mice; D023421:Models, Animal; D009419:Nerve Tissue Proteins / Q000378:metabolism*
chemical_list: D000090023:Metallothionein 3; C000715430:Mt3 protein, mouse; D009419:Nerve Tissue Proteins