27 research outputs found
Schematic model for 2-AA mediated molecular mechanisms of mitochondrial dysfunction in skeletal muscle.
<p>2-AA triggers mitochondrial dysfunction via the down-regulation of peroxisome proliferative activated receptor, gamma, coactivator (PGC)-1β, peroxisome proliferator activated receptor (PPAR)-γ, sirtuin (Sirt)-1, the insulin signaling pathway, overall energy metabolism, and increased lipid accumulation.</p
NMR spectra from <sup>1</sup>H-NMR HRMAS analysis of gastrocnemius skeletal muscle from 2-AA treated versus control mice.
<p>The spectra were acquired from 2-AA treated mice at 4 d versus control mice, and scaled to the phosphocreatine plus creatine peak (3.02 ppm). Resonance signals of lipids correspond to: 1) terminal methyl CH<sub>3</sub> protons (0.9 ppm); 2) acyl chain methylene protons (CH<sub>2</sub>)<sub>n</sub> of intramyocellular lipids (IMCLs) (1.3 ppm); 3) methylene protons CH<sub>2</sub>C-CO (1.6 ppm); 4) allylic methylene protons C = C-CH<sub>2</sub>-C of monounsaturated fatty acyl moieties (MUFAs) (2.05 ppm); 5) α methylene protons CH<sub>2</sub>CO (2.25 ppm); 6) diallylic methylene protons  = C-CH<sub>2</sub>-C =  of polyunsaturated fatty acyl moieties (PUFAs); and 7) N-methyl protons of phosphocreatine and creatine (3.0 ppm), respectively. The NMR spectra demonstrate increased biomarkers of insulin resistance IMCLs.</p
Differential expression of genes involved in fatty acid oxidation in mouse skeletal muscle at 4-AA treatment versus control muscle.
<p>(+) Upregulation of genes compared with control untreated muscle.</p><p>(−) Downregulation of genes compared with control untreated muscle.</p
2-AA treatment down-regulates muscle function.
<p>Black bars indicate the number of down-regulated genes; gray bars indicate the number of up-regulated genes, in the skeletal muscle of mice 4 days post 2-AA treatment versus control mice (left vertical axis). The negative log10 of p-values represented by gray triangles are indicated on the right vertical axis.</p
Downregulation of muscle contraction genes in mouse skeletal muscle at 4-AA treatment versus control muscle.
<p>(−) Downregulation of genes compared with control untreated muscle.</p
2-AA treatment dampens key metabolic protein levels in mouse skeletal muscle cells.
<p>Western blotting of cellular extracts with specific antibodies of PGC-1β, PPAR-γ and Sirt-1 in 2-AA treated cells at the indicated time points. One representative experiment (out of three) is shown. Loading was normalized relative to mouse α-tubulin. Densitometric data are the average of three replicate experiments and are expressed as mean ± SD (vertical bars).*p<0.05 vs. naïve. DU, densitometric units.</p
Effects of 2-AA on viability of mouse muscle cells.
<p>MTT assay measuring cell viability in mouse skeletal muscle cells (C2C12) after treatment with 0.8 mM 2-AA over time, as indicated in the figure. SDs (vertical bars) were calculated from three replicate experiments.</p
NMR spectra of <i>in vivo</i><sup>31</sup>P NMR saturation-transfer on mouse hind limb skeletal muscle.
<p>Representative summed <sup>31</sup>P-NMR spectra acquired from control and 2-AA treated mice at day 4, before (A) and after (B) saturation of the γ-ATP resonance, with the difference spectrum between the two shown below (A–B). The arrow on γ-ATP indicates the position of saturation (sat) by rf irradiation (−2.4 ppm). ppm, chemical shift in parts per million.</p
Differential expression of key metabolic genes in skeletal muscle from 2-AA treated mice versus untreated control mice.
<p>Values are the relative expression intensity of the 2-AA treated versus control mice after 4 d Gene annotations for biological functions are from the Gene Ontology Consortium and the Ingenuity database.</p><p>(+) Upregulation of genes compared with control untreated muscle.</p><p>(−) Downregulation of genes compared with control untreated muscle.</p
<i>In vivo</i><sup>31</sup>P-NMR saturation transfer analysis of limb skeletal muscle from control and 2-AA treated mice.
<p>Values are means ± SEM; ΔM/M<sub>0</sub> is the fractional change in P<sub>i</sub> or PCr magnetization as a result of saturation transfer; T<sub>1obs</sub> is the observed spin lattice relaxation time of P<sub>i</sub> or PCr during γ-ATP saturation in seconds; <i>Κ<sub>f</sub></i> is the rate constant for the reactions P<sub>i</sub> → γ-ATP and PCr → γ-ATP, calculated as (1/T<sub>1obs</sub>) × (Δ<i>M/M<sub>0</sub></i>). ATP synthesis is calculated as P<sub>i</sub> or PCr × <i>Κ<sub>f</sub></i>. NS: not significant. Unpaired one-tailed Student's t-test was used for the comparisons.</p