Diet-induced lethality due to deletion of the Hdac3 gene in heart and skeletal muscle

Abstract

Many human diseases result from the influence of the nutritional environment on gene expression. The environment interacts with the genome by altering the epigenome, including covalent modification of nucleosomal histones. Here, we report a novel and dramatic influence of diet on the phenotype and survival of mice in which histone deacetylase 3 (Hdac3) is deleted postnatally in heart and skeletal muscle. Although embryonic deletion of myocardial Hdac3 causes major cardiomyopathy that reduces survival, we found that excision of Hdac3 in heart and muscle later in development leads to a much milder phenotype and does not reduce survival when mice are fed normal chow. Remarkably, upon switching to a high fat diet, the mice begin to die within weeks and display signs of severe hypertrophic cardiomyopathy and heart failure. Down-regulation of myocardial mitochondrial bioenergetic genes, specifically those involved in lipid metabolism, precedes the full development of cardiomyopathy, suggesting that HDAC3 is important in maintaining proper mitochondrial function. These data suggest that loss of the epigenomic modifier HDAC3 causes dietary lethality by compromising the ability of cardiac mitochondria to respond to changes of nutritional environment. In addition, this study provides a mouse model for diet-inducible heart failure.

FIGURE 1.

Efficient postnatal deletion of HDAC3 in cardiac and skeletal muscle by MCK-Cre. A, Western blot analysis of 4-month-old mice. Skeletal muscle is from quadriceps. WAT, white adipose tissue. B, quantitative PCR analysis of HDAC3 mRNA in 4-month-old mice. n = 3. Error bar, S.E. *, p < 0.05. C, quantitative PCR analysis of HDAC3 in mice at the age of 1 day and at 1, 3, and 6 weeks. n = 4. Error bar, S.E. WT, wild-type control; HDAC3^fl/fl, HDAC3 flox/flox; KO (MCH3-KO), HDAC3 flox/flox with MCK-Cre.

FIGURE 2.

Mild alterations in HDAC3-deficient heart on normal chow. A and B, Kaplan-Meier survival curves and body weight on normal chow. n = 12–15. C, gross picture of hearts at the age of 4 months. D, heart weight (HW) to tibia length (TL) ratio of 4-month-old mice on normal chow. n = 7–8. Error bar, S.E. *, p < 0.05. E, quantitative PCR analysis of 4-month-old mice for cardiac ANP and BNP, markers for heart failure. n = 3. Error bar, S.E. F, trichrome stain of hearts from 8-month-old mice.

FIGURE 3.

Echocardiography analysis of cardiac structure and function on 4-month-old mice on normal chow. A, cardiac structure data. B, contractile function data. n = 4–5. Error bar, S.E. *, p < 0.05. FS, left ventricular fractional shortening; EF, left ventricular ejection fraction; IVRT, isovolumic relaxation time; LVIDd, left ventricular diameter during diastole; LVIDs, left ventricular diameter during systole; LA, left atrium area; LVPW, left ventricular posterior wall thickness during diastole; RVAW, right ventricular anterior wall thickness; IVS, interventricular septal thickness during diastole; HR, heart rate.

FIGURE 4.

No significant alteration of function or morphology of HDAC3-deficient skeletal muscles. A, grip strength measurement on 8-month-old mice. n = 5. B, extensor digitorum longus (EDL) and soleus (Sol) muscle weight to tibia length ratio of 8-month-old mice. n = 5. Error bar, S.E. C, H&E stain of gastrocnemius (Gastroc) muscle from 8-month-old mice.

FIGURE 5.

HDAC3-deficient myocardium is inefficient in metabolizing lipid. A, myocardial triglyceride (TG) content of 4-month-old mice on normal chow that were either fed or fasted for 24 h. n = 5. Error bar, S.E. *, p < 0.05. B, Oil Red O stain of the myocardium after 24 h of fasting.

FIGURE 6.

Dietary lipid overload induced severe cardiac defects in mice lacking cardiac HDAC3. A, Kaplan-Meier survival curves on high fat diet (HFD). n = 10 for WT and n = 12 for KO. B, KO mice have normal weight gain on HFD. C, gross picture of hearts from 4-month-old mice after feeding HFD for 3 months. D, heart weight (HW) to tibia length (TL) ratio of 4-month-old mice on HFD. n = 4–5. Error bar, S.E. *, p < 0.05. E, quantitative PCR analysis of myocardial ANP and BNP from 4-month-old mice. n = 4–5. Error bar, S.E. *, p < 0.05. F, trichrome stain of hearts from 4-month-old mice on HFD. G, wheat germ agglutinin (WGA) staining of cross-sections of ventricles from 4-month-old mice on HFD. Myocyte diameter was quantified on six random ×20 fields of view from each heart. n = 3 for WT and n = 5 for KO. Error bar, S.E. *, p < 0.05.

FIGURE 7.

Echocardiography analysis of cardiac structure and function on 4-month-old mice on high fat diet. A, cardiac structure data. B, contractile function data. n = 4–5. Error bar, S.E. *, p < 0.05. C, representative short axis M-mode images from echocardiography.