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. 2015 Aug:5:140-148.
doi: 10.1016/j.redox.2015.04.005. Epub 2015 Apr 15.

Neuron specific reduction in CuZnSOD is not sufficient to initiate a full sarcopenia phenotype

Kavithalakshmi Sataranatarajan  1 , Rizwan Qaisar  1 , Carol Davis  2 , Giorgos K Sakellariou  3 , Aphrodite Vasilaki  3 , Yiqiang Zhang  4 , Yuhong Liu  5 , Shylesh Bhaskaran  1 , Anne McArdle  3 , Malcolm Jackson  3 , Susan V Brooks  2 , Arlan Richardson  6 , Holly Van Remmen  7
Affiliations

Neuron specific reduction in CuZnSOD is not sufficient to initiate a full sarcopenia phenotype

Kavithalakshmi Sataranatarajan et al. Redox Biol. 2015 Aug.

Abstract

Our previous studies showed that adult (8 month) mice lacking CuZn-superoxide dismutase (CuZnSOD, Sod1KO mice) have neuromuscular changes resulting in dramatic accelerated muscle atrophy and weakness that mimics age-related sarcopenia. We have further shown that loss of CuZnSOD targeted to skeletal muscle alone results in only mild weakness and no muscle atrophy. In this study, we targeted deletion of CuZnSOD specifically to neurons (nSod1KO mice) and determined the effect on muscle mass and weakness. The nSod1KO mice show a significant loss of CuZnSOD activity and protein level in brain and spinal cord but not in muscle tissue. The masses of the gastrocnemius, tibialis anterior and extensor digitorum longus (EDL) muscles were not reduced in nSod1KO compared to wild type mice, even at 20 months of age, although the quadriceps and soleus muscles showed small but statistically significant reductions in mass in the nSod1KO mice. Maximum isometric specific force was reduced by 8-10% in the gastrocnemius and EDL muscle of nSod1KO mice, while soleus was not affected. Muscle mitochondrial ROS generation and oxidative stress measured by levels of reactive oxygen/nitrogen species (RONS) regulatory enzymes, protein nitration and F2-isoprostane levels were not increased in muscle from the nSod1KO mice. Although we did not find evidence of denervation in the nSod1KO mice, neuromuscular junction morphology was altered and the expression of genes associated with denervation acetylcholine receptor subunit alpha (AChRα), the transcription factor, Runx1 and GADD45α) was increased, supporting a role for neuronal loss of CuZnSOD initiating alterations at the neuromuscular junction. These results and our previous studies support the concept that CuZnSOD deficits in either the motor neuron or muscle alone are not sufficient to initiate a full sarcopenic phenotype and that deficits in both tissues are required to recapitulate the loss of muscle observed in Sod1KO mice.

Keywords: CuZnSOD; Muscle atrophy; Neuromuscular junction; Oxidative stress; Sarcopenia.

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Figures

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Graphical abstract
Fig. 1
Fig. 1
Generation of neuron-specific Sod1-knockout (nSod1KO) mice. (A) Native gels stained for CuZnSOD and MnSOD enzyme activities in gastrocnemius, quadriceps, brain and spinal cord of wild type and nSod1KO mice. (B) Western blot analysis of CuZnSOD expression in gastrocnemius, quadriceps, brain and spinal cord of wild type and nSod1KO (n=3–6 mice in each group between 7 and 18 months of age). Both males and females were used to generate these data.
Fig. 2
Fig. 2
Muscle mass and function of the nSod1KO mice. (A) Muscle mass expressed as percentage of body mass. (B) Maximum isometric specific force (N/cm2) of gastrocnemius, extensor digitorum longus and soleus muscle (⁎p<0.05 vs. wild type by Students t-test, n=8–10 mice per group, 20 month old mice, wild type—black bars, nSod1KO—white bars).
Fig. 3
Fig. 3
Fiber diameter, fiber type, myonuclear domain (MND) and number of nuclei in gastrocnemius and quadriceps muscle of the nSod1KO mice. (A) Percentage distribution of fiber diameter of gastrocnemius and quadriceps muscle. (B) MND size from single muscle fiber segments of gastrocnemius (GTN) and quadriceps (QUAD). Rhodamine–phalloidin labeled actin is shown in red and nuclei visualized by DAPI in blue. Scale bar denotes 50 µm. (C) Fibers with central nuclei in the gastrocnemius and quadriceps. (D) Percentage of fiber type distribution in the gastrocnemius and quadriceps (⁎p<0.05 vs wild type by t-test, n=3–7 mice in each group). 5 and 20 months old mice were used (wild type–black bars, nSod1KO–white bars).
Fig. 4
Fig. 4
Acetylcholine receptor morphology and denervation associated markers in nSod1KO mice (A) Acetylcholine receptors from gastrocnemius (A–D) and quadriceps muscles (E–H) (scale bar=10 µm for receptors and 40 µm for clusters). (B) mRNA levels of the denervation markers. In gastrocnemius, ⁎p<0.001 nSod1KO vs wild type, ⁎p<0.01 Sod1KO vs wild type for AChRα mRNA; ⁎p<0.01 nSod1KO vs wild type, ⁎p<0.0001 Sod1KO vs wild type for Runx1 mRNA; ⁎p<0.05 nSod1KO vs wild type, ⁎p<0.001 Sod1KO vs wild type for GADD45α mRNA by analysis of variance (ANOVA) with comparisons between groups performed using Newman–Keuls post-hoc test using Prism6 software. In quadriceps, ⁎p<0.01 nSod1KO vs wild type for AChRα mRNA; ⁎p<0.0001 nSod1KO vs wild type for Runx1 mRNA, ⁎p<0.05 nSod1KO vs wild type for GADD45α mRNA by t-test. Mice were 16–18 months of age and n=4–13 mice per group (wild type—black bars, nSod1KO—white bars, Sod1KO—gray bars).
Fig. 5
Fig. 5
Mitochondrial ROS measurement and F2-isoprostane levels in nSod1KO mice. (A) Hydrogen peroxide generation in mitochondria isolated from gastrocnemius muscle (n=6–11 mice per group). (B) F2-isoprostane levels in quadriceps muscle (⁎p<0.05 in wild type vs Sod1KO by Students t test; n=3–5 mice per group) (wild type—black bars, Sod1KO—gray bars, nSod1KO—white bars).
Fig. 6
Fig. 6
Markers of oxidative damage to proteins in nSod1KO mice. (A) Protein nitration in gastrocnemius and quadriceps. (B) Expression of peroxynitrite reductase, PRXV in the gastrocnemius and quadriceps (n=4 mice per group, 17–22 month old mice with quantification on the right) (wild type—black bars, nSod1KO—white bars).
Fig. 7
Fig. 7
RONS regulatory protein contents in nSod1KO mice. Expression of MnSOD, endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) proteins of gastrocnemius and quadriceps by western blot with quantification on the right (n=4 mice per group, 17–22 month old mice) (wild type—black bars, nSod1KO—white bars).
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References

    1. Muller F.L., Song W., Liu Y., Chaudhuri A., Pieke-Dahl S., Strong R., Huang T.T., Epstein C.J., Roberts L.J., 2nd, Csete M. Absence of CuZn superoxide dismutase leads to elevated oxidative stress and acceleration of age-dependent skeletal muscle atrophy. Free Radical Biology and Medicine. 2006;40(11):1993–2004. 16716900 - PubMed
    1. Jang Y.C., Lustgarten M.S., Liu Y., Muller F.L., Bhattacharya A., Liang H., Salmon A.B., Brooks S.V., Larkin L., Hayworth C.R. Increased superoxide in vivo accelerates age-associated muscle atrophy through mitochondrial dysfunction and neuromuscular junction degeneration. FASEB Journal. 2010;24(5):1376–1390. 20040516 - PMC - PubMed
    1. Larkin L.M., Davis C.S., Sims-Robinson C., Kostrominova T.Y., Van Remmen H., Richardson A., Feldman E.L., Brooks S.V. Skeletal muscle weakness due to deficiency of CuZn-superoxide dismutase is associated with loss of functional innervation. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 2011;301(5):R1400–R1407. 21900648 - PMC - PubMed
    1. Sakellariou G.K., Davis C.S., Shi Y., Ivannikov M.V., Zhang Y., Vasilaki A., Macleod G.T., Richardson A., Van Remmen H., Jackson M.J. Neuron-specific expression of CuZnSOD prevents the loss of muscle mass and function that occurs in homozygous CuZnSOD-knockout mice. FASEB Journal. 2014;28(4):1666–1681. 24378874 - PMC - PubMed
    1. Zhang Y., Davis C., Sakellariou G.K., Shi Y., Kayani A.C., Pulliam D., Bhattacharya A., Richardson A., Jackson M.J., McArdle A. CuZnSOD gene deletion targeted to skeletal muscle leads to loss of contractile force but does not cause muscle atrophy in adult mice. FASEB Journal. 2013;27(9):3536–3548. 23729587 - PMC - PubMed

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