Genetic disruption of myostatin reduces the development of proatherogenic dyslipidemia and atherogenic lesions in Ldlr null mice - PubMed (original) (raw)

. 2009 Aug;58(8):1739-48.

doi: 10.2337/db09-0349. Epub 2009 Jun 9.

Affiliations

Genetic disruption of myostatin reduces the development of proatherogenic dyslipidemia and atherogenic lesions in Ldlr null mice

Powen Tu et al. Diabetes. 2009 Aug.

Abstract

Objective: Insulin-resistant states, such as obesity and type 2 diabetes, contribute substantially to accelerated atherogenesis. Null mutations of myostatin (Mstn) are associated with increased muscle mass and decreased fat mass. In this study, we determined whether Mstn disruption could prevent the development of insulin resistance, proatherogenic dyslipidemia, and atherogenesis.

Research design and methods: C57BL/6 Ldlr(-/-) mice were cross-bred with C57BL/6 Mstn(-/-) mice for >10 generations to generate Mstn(-/-)/Ldlr(-/-) double-knockout mice. The effects of high-fat/high-cholesterol diet on body composition, plasma lipids, systemic and tissue-specific insulin sensitivity, hepatic steatosis, as well as aortic atheromatous lesion were characterized in Mstn(-/-)/Ldlr(-/-) mice in comparison with control Mstn(+/+)/Ldlr(-/-) mice.

Results: Compared with Mstn(+/+)/Ldlr(-/-) controls, Mstn(-/-)/ Ldlr(-/-) mice were resistant to diet-induced obesity, and had greatly improved insulin sensitivity, as indicated by 42% higher glucose infusion rate and 90% greater muscle [(3)H]-2-deoxyglucose uptake during hyperinsulinemic-euglycemic clamp. Mstn(-/-)/Ldlr(-/-) mice were protected against diet-induced hepatic steatosis and had 56% higher rate of hepatic fatty acid beta-oxidation than controls. Mstn(-/-)/Ldlr(-/-) mice also had 36% lower VLDL secretion rate and were protected against diet-induced dyslipidemia, as indicated by 30-60% lower VLDL and LDL cholesterol, free fatty acids, and triglycerides. Magnetic resonance angiography and en face analyses demonstrated 41% reduction in aortic atheromatous lesions in Ldlr(-/-) mice with Mstn deletion.

Conclusions: Inactivation of Mstn protects against the development of insulin resistance, proatherogenic dyslipidemia, and aortic atherogenesis in Ldlr(-/-) mice. Myostatin may be a useful target for drug development for prevention and treatment of obesity and its associated type 2 diabetes and atherosclerosis.

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Figures

FIG. 1.

FIG. 1.

Effects of Mstn disruption on body fat accumulation in Ldlr_−/− mice. A: Representative gross appearance (top panel) and micro-CT image of visceral and subcutaneous fat (bottom panel) of mice after 12 weeks of HFD (HF-diet). c, cecum; vf, visceral fat, sf, subcutaneous fat. B: NMR analysis of total fat at baseline (time 0) and after 5 and 10 weeks of HFD. Mstn+/+/Ldlr_+/+, ♦; Mstn+/+/Ldlr_−/−, ○; Mstn+−/Ldlr_−/−, ▲; Mstn+−_/Ldlr_−/−, ●. C: Inguinal, epididymal, perirenal, and intrascapular brown fat weights of mice after 12 weeks of HFD. D: Representative gross appearance of hind-limb muscles (left panel) and quadriceps muscle weights (right panel) of mice after 12 weeks of HFD. ++/++, Mstn+/+/Ldlr+/+. ++/−−, Mstn+/+/Ldlr_−/−. +−/−−, Mstn+−/Ldlr_−/−. −−/−−, Mstn_−/−/Ldlr_−/−. Data are expressed as means ± SE (n = 11–21). **P < 0.01 compared with all other genotypes. (A high-quality digital representation of this figure is available in the online issue.)

FIG. 2.

FIG. 2.

Effects of Mstn disruption on atherogenesis progression in Ldlr_−/− mice. A: Representative MRA of aortic arch and its major branches. BCA, brachiocephalic artery. B: Cross-sectional image of BCA. C and D: Symmetry coefficient (ratio of the largest to the smallest diameter) (C), and cross-sectional area (D) of BCA lumen (n = 4). E: Oil Red O staining of atherosclerotic lesions in aortic root at the level of the aortic valves (top panel). Magnification 40×. Gross aortic arch and branches (bottom panel) (n = 9–20). F and G: Sudan IV staining of en face aortas (F) and quantitative analyses of atherosclerotic lesion areas (percent of total aortic surface area) (G) (n = 9–20). ++/++, Mstn+/+/Ldlr_+/+. ++/−−, Mstn+/+/Ldlr_−/−. +−/−−, Mstn+−/Ldlr_−/−. −−/−−, Mstn_−/−/Ldlr_−/−. Data are expressed as means ± SE (n = 11–21). **P < 0.05. **P < 0.01. (A high-quality digital representation of this figure is available in the online issue.)

FIG. 3.

FIG. 3.

Atherogenic lipid profile in Ldlr_−/− mice with Mstn deletion. A and B: Fasting plasma FFA, triglycerides, and cholesterol levels of mice at baseline (A) and after 10 weeks of HFD (HF-diet) (B). C and D: Lipoprotein profile in Mstn+/+/Ldlr_−/− (○) and Mstn_−/−/Ldlr_−/− (●) mice after 11 weeks of HFD. Data are presented as average cholesterol (C) and triglycerides (D) distribution for each group. E: Plasma apoA1- and apoB100-containing lipoprotein particles before and after induction of HFD. The graphs demonstrate the quantification of each molecule, displayed as apoB100/apoA1 ratio. Averages were taken from four different gels. Blood was drawn from mice after 10 weeks of HFD. ++/−−, Mstn+/+_/Ldlr_−/−. −−/−−, Mstn_−/−/Ldlr_−/−. Data are shown as the means ± SE (n = 7–10). *P < 0.05, **P < 0.01.

FIG. 4.

FIG. 4.

Metabolic studies in Ldlr_−/− mice with Mstn deletion. A–C: Fasting blood glucose (A), plasma insulin (B), and glucose (mg/dl) × insulin product (μIU/ml) ratio (C) of Mstn+/+/Ldlr_−/− and Mstn_−/−/Ldlr_−/− mice after 8 weeks of HFD. D–G: Hyperinsulinemic-euglycemic clamp studies in mice after 12 weeks of HFD. Trace of blood glucose and GIR during the 2-h clamp (D) (○ and ●, blood glucose; □ and ■, GIR), average GIR (E), glucose uptake in quadriceps muscle (F), and average plasma insulin during clamp period (G). H: Akt serine-473 and GSKα/β serine-21/9 phosphorylation in the quadriceps muscle of mice. The graphs demonstrate the quantification of phosphorylated form of each molecule. Averages were taken from three different experiments. ++/−−, Mstn+/+_/Ldlr_−/−. −−/−−, Mstn_−/−/Ldlr_−/−. AU, arbitrary units. Data are shown as the means ± SE (n = 7–10). *P < 0.05, **P < 0.01.

FIG. 5.

FIG. 5.

Effects of Mstn deletion on liver of Ldlr_−/− mice. A: Hematoxylin and eosin (H&E) and Oil Red O staining of the liver of Mstn+/+/Ldlr_−/− and Mstn_−/−/Ldlr_−/− mice after 12 weeks of HFD (HF-diet). B and C: mRNA expression of Srebf1 (B) and fatty acid synthase (Fasn) (C) in the liver of mice before and after 12 weeks of HFD. Values are expressed with respect to Mstn+/+/Ldlr_−/− controls. D: Protein expression of fatty acid synthase. Averages were taken from three different gels. E: Plasma apoB100 at 0 and 180 min after injection of Triton WR1339, a lipoprotein lipase inhibitor. VLDL secretion is determined as percent increase of apoB100 from baseline. Averages were taken from three different gels. F: Akt serine-473 and GSKα/β serine-21/9 phosphorylation in the liver of mice after 12 weeks of HFD. The graphs demonstrate the quantification of phosphorylation of each molecule. ++/−−, Mstn+/+/Ldlr_−/−. −−/−−, Mstn_−/−/Ldlr_−/−. AU, arbitrary units. Data are shown as the means ± SE (n = 7–10). *P < 0.05, **P < 0.01. (A high-quality digital representation of this figure is available in the online issue.)

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