title: An analysis of interactions between fluorescently-tagged mutant and wild-type SOD1 in intracellular inclusions.
abstract: BACKGROUND
  By mechanisms yet to be discerned, the co-expression of high levels of wild-type human superoxide dismutase 1 (hSOD1) with variants of hSOD1 encoding mutations linked familial amyotrophic lateral sclerosis (fALS) hastens the onset of motor neuron degeneration in transgenic mice. Although it is known that spinal cords of paralyzed mice accumulate detergent insoluble forms of WT hSOD1 along with mutant hSOD1, it has been difficult to determine whether there is co-deposition of the proteins in inclusion structures.
  
  
  RESULTS
  In the present study, we use cell culture models of mutant SOD1 aggregation, focusing on the A4V, G37R, and G85R variants, to examine interactions between WT-hSOD1 and misfolded mutant SOD1. In these studies, we fuse WT and mutant proteins to either yellow or red fluorescent protein so that the two proteins can be distinguished within inclusions structures.
  
  
  CONCLUSIONS
  Although the interpretation of the data is not entirely straightforward because we have strong evidence that the nature of the fused fluorophores affects the organization of the inclusions that form, our data are most consistent with the idea that normal dimeric WT-hSOD1 does not readily interact with misfolded forms of mutant hSOD1. We also demonstrate the monomerization of WT-hSOD1 by experimental mutation does induce the protein to aggregate, although such monomerization may enable interactions with misfolded mutant SOD1. Our data suggest that WT-hSOD1 is not prone to become intimately associated with misfolded mutant hSOD1 within intracellular inclusions that can be generated in cultured cells.
authors.affiliation: Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, SantaFe HealthCare Alzheimer's Disease Research Center, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Qualls
authors.affiliation: Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, SantaFe HealthCare Alzheimer's Disease Research Center, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Keith
authors.initials: K
authors.lastname: Crosby
authors.affiliation: Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, SantaFe HealthCare Alzheimer's Disease Research Center, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Hilda
authors.initials: H
authors.lastname: Brown
authors.affiliation: Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, SantaFe HealthCare Alzheimer's Disease Research Center, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: David R
authors.initials: DR
authors.lastname: Borchelt
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D002479:Inclusion Bodies / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D055503:Protein Multimerization; D012503:Saponins / Q000378:metabolism; D013482:Superoxide Dismutase / Q000737:chemistry / Q000502:physiology*; D000072105:Superoxide Dismutase-1; D000097573:Red Fluorescent Protein
chemical_list: D001426:Bacterial Proteins; D008164:Luminescent Proteins; D050505:Mutant Proteins; D012503:Saponins; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000097573:Red Fluorescent Protein; C000606290:SOD1 protein, human; C054562:yellow fluorescent protein, Bacteria; C000606291:Sod1 protein, mouse