Soluble misfolded subfractions of mutant superoxide dismutase-1s are enriched in spinal cords throughout life in murine ALS models.
Mutants of superoxide dismutase-1 (SOD1) cause ALS by an unidentified cytotoxic mechanism. We have previously shown that the stable SOD1 mutants D90A and G93A are abundant and show the highest levels in liver and kidney in transgenic murine ALS models, whereas the unstable G85R and G127X mutants are scarce but enriched in the CNS. These data indicated that minute amounts of misfolded SOD1 enriched in the motor areas might exert the ALS-causing cytotoxicity. A hydrophobic interaction chromatography (HIC) protocol was developed with the aim to determine the abundance of soluble misfolded SOD1 in tissues in vivo. Most G85R and G127X mutant SOD1s bound in the assay, but only minute subfractions of the D90A and G93A mutants. The absolute levels of HIC-binding SOD1 were, however, similar and broadly inversely related to lifespans in the models. They were generally enriched in the susceptible spinal cord. The HIC-binding SOD1 was composed of disulfide-reduced subunits lacking metal ions and also subunits that apparently carried nonnative intrasubunit disulfide bonds. The levels were high from birth until death and were comparable to the amounts of SOD1 that become sequestered in aggregates in the terminal stage. The HIC-binding SOD1 species ranged from monomeric to trimeric in size. These species form a least common denominator amongst SOD1 mutants with widely different molecular characteristics and might be involved in the cytotoxicity that causes ALS.
Zetterström
Per
P
Department of Medical Biosciences, Umeå University, SE-901 85 Umeå, Sweden.
Stewart
Heather G
HG
Bergemalm
Daniel
D
Jonsson
P Andreas
PA
Graffmo
Karin S
KS
Andersen
Peter M
PM
Brännström
Thomas
T
Oliveberg
Mikael
M
Marklund
Stefan L
SL
D000818:Animals; D004195:Disease Models, Animal; D014644:Genetic Variation; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D016472:Motor Neuron Disease / Q000201:enzymology / Q000235:genetics*; D009154:Mutation; D010084:Oxidation-Reduction; D011489:Protein Denaturation; D017510:Protein Folding; D021122:Protein Subunits; D017384:Sequence Deletion; D013116:Spinal Cord / Q000254:growth & development / Q000503:physiopathology*; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D000072105:Superoxide Dismutase-1
D021122:Protein Subunits; C000606290:SOD1 protein, human; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1
Science. 1999 Dec 24;286(5449):2498-500
10617463
J Neurosci. 2000 Dec 15;20(24):9119-25
11124989
Amyotroph Lateral Scler Other Motor Neuron Disord. 2003 Jun;4(2):62-73
14506936
Brain. 2004 Jan;127(Pt 1):73-88
14534160
Protein Expr Purif. 2004 Oct;37(2):311-9
15358352
J Clin Invest. 1984 Oct;74(4):1398-403
6541229
Nature. 1993 Mar 4;362(6415):59-62
8446170
Science. 1994 Jun 17;264(5166):1772-5
8209258
Brain. 1995 Jun;118 ( Pt 3):707-19
7600088
Nat Genet. 1995 May;10(1):61-6
7647793
Proc Natl Acad Sci U S A. 1996 May 28;93(11):5472-7
8643599
Neuron. 1997 Feb;18(2):327-38
9052802
Ann Neurol. 1997 Apr;41(4):497-504
9124807
J Neurochem. 1997 Aug;69(2):675-81
9231727
Science. 1998 Sep 18;281(5384):1851-4
9743498
Nat Neurosci. 1999 Jan;2(1):50-6
10195180
Proc Natl Acad Sci U S A. 2004 Nov 9;101(45):15893-8
15522970
J Biol Chem. 2005 Apr 29;280(17):17266-74
15691826
Brain. 2005 Jun;128(Pt 6):1323-9
15843422
Proc Natl Acad Sci U S A. 2005 Jul 12;102(28):9754-9
15987780
J Biol Chem. 2005 Aug 19;280(33):29771-9
15958382
Neurobiol Dis. 2005 Dec;20(3):943-52
16046140
Brain. 2006 Feb;129(Pt 2):451-64
16330499
J Neurochem. 2006 Mar;96(5):1277-88
16441516
J Neurosci. 2006 Apr 19;26(16):4147-54
16624935
Proc Natl Acad Sci U S A. 2006 May 2;103(18):7148-53
16636274
Proc Natl Acad Sci U S A. 2006 Jul 5;103(27):10218-23
16798882
Neuron. 2006 Oct 5;52(1):39-59
17015226
J Neuropathol Exp Neurol. 2006 Dec;65(12):1126-36
17146286