No effective way to slow or halt the progressive paralysis due to ALS now exists. A handle on etiology has been provided by the discovery that mutation in SOD1 causes a subset of cases. Decreased stability and decreased binding of zinc or copper, gain of a deleterious oxidative activity, binding of heat shock proteins, and aggregation, have all been proposed as causative. Yet the mystery remains. Oxidative stress seems a likely cause. We have developed manganese porphyrin derivatives that efficiently scavenge O2-, ONOO-, and CO3-. When tested in a murine model of FALS, by Dr. John Crow, one of our manganese porphyrins dramatically delayed paralysis and death (See preliminary data). We synthesized new cationic manganese porphyrins with graded hydrophobicities and would like to prepare amounts large enough for similar testing, in the hope that they may be more efficacious. We will explore the role of carbonate radical in imposing the oxidative stress that can contribute in death of motor neurons. Toward this end we will start by seeing whether CO2 exacerbates oxidative stress in suspensions of SOD-deficient strains as compared to parental strains of E. coli. Mn porphyrins should oppose these toxic effects of CO2. We will test the degree to which our Mn porphyrins suppress NOS activity in N2a and NSC-34 cells, perhaps by way of down-regulating the biosynthesis of Hsp90. In relation to the latter we will examine the effect of NO on the binding of Hsps to mutant SOD1, by immunoprecipitation. We will also examine the degree to which the wild-type and mutant SOD1s are covalently cross-linked in these cells and the effects of NO on this crosslinking. Finally, since we have shown that our manganese porphyrins can catalytically oxidize the NO cofactor, tetrahydrobiopterin, we will test this alternative, or parallel, pathway of NOS inhibition. The goal of this work is to increase our understanding of the development of ALS and at the same time to develop compounds that will be efficacious in ameliorating the symptoms of this disease. The compounds we find most effective in our models will be tested first in Dr. Crow's G93 A murine model of FALS and then forwarded to Incara Pharmaceuticals for clinical development.

National Institute of Health (NIH)
National Institute of Environmental Health Sciences (NIEHS)
Exploratory/Developmental Grants (R21)
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Special Emphasis Panel (ZRG1-NDBG (01))
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Kirshner, Annette G
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Duke University
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Reboucas, Julio S; DeFreitas-Silva, Gilson; Spasojevic, Ivan et al. (2008) Impact of electrostatics in redox modulation of oxidative stress by Mn porphyrins: protection of SOD-deficient Escherichia coli via alternative mechanism where Mn porphyrin acts as a Mn carrier. Free Radic Biol Med 45:201-10
DeFreitas-Silva, Gilson; Reboucas, Julio S; Spasojevic, Ivan et al. (2008) SOD-like activity of Mn(II) beta-octabromo-meso-tetrakis(N-methylpyridinium-3-yl)porphyrin equals that of the enzyme itself. Arch Biochem Biophys 477:105-12
Spasojevic, Ivan; Chen, Yumin; Noel, Teresa J et al. (2008) Pharmacokinetics of the potent redox-modulating manganese porphyrin, MnTE-2-PyP(5+), in plasma and major organs of B6C3F1 mice. Free Radic Biol Med 45:943-9
Okado-Matsumoto, Ayako; Fridovich, Irwin (2007) Putative denitrosylase activity of Cu,Zn-superoxide dismutase. Free Radic Biol Med 43:830-6
Liochev, Stefan I; Fridovich, Irwin (2007) The effects of superoxide dismutase on H2O2 formation. Free Radic Biol Med 42:1465-9
Okado-Matsumoto, Ayako; Guan, Ziqiang; Fridovich, Irwin (2006) Modification of cysteine 111 in human Cu,Zn-superoxide dismutase. Free Radic Biol Med 41:1837-46