Histone acetyltransferase inhibitors antagonize AMP-activated protein kinase in postmortem glycolysis

Objective The purpose of this study was to investigate the influence of AMP-activated protein kinase (AMPK) activation on protein acetylation and glycolysis in postmortem muscle to better understand the mechanism by which AMPK regulates postmortem glycolysis and meat quality. Methods A total of 32 mice were randomly assigned to four groups and intraperitoneally injected with 5-Aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR, a specific activator of AMPK), AICAR and histone acetyltransferase inhibitor II, or AICAR, Trichostatin A (TSA, an inhibitor of histone deacetylase I and II) and Nicotinamide (NAM, an inhibitor of the Sirt family deacetylases). After mice were euthanized, the Longissimus dorsi muscle was collected at 0 h, 45 min, and 24 h postmortem. AMPK activity, protein acetylation and glycolysis in postmortem muscle were measured. Results Activation of AMPK by AICAR significantly increased glycolysis in postmortem muscle. At the same time, it increased the total acetylated proteins in muscle 45 min postmortem. Inhibition of protein acetylation by histone acetyltransferase inhibitors reduced AMPK activation induced increase in the total acetylated proteins and glycolytic rate in muscle early postmortem, while histone deacetylase inhibitors further promoted protein acetylation and glycolysis. Several bands of proteins were detected to be differentially acetylated in muscle with different glycolytic rates. Conclusion Protein acetylation plays an important regulatory role in postmortem glycolysis. As AMPK mediates the effects of pre-slaughter stress on postmortem glycolysis, protein acetylation is likely a mechanism by which antemortem stress influenced postmortem metabolism and meat quality though the exact mechanism is to be elucidated

Effects of cortisol and dexamethasone on insulin signalling pathways in skeletal muscle of the ovine fetus during late gestation.

Before birth, glucocorticoids retard growth, although the extent to which this is mediated by changes in insulin signalling pathways in the skeletal muscle of the fetus is unknown. The current study determined the effects of endogenous and synthetic glucocorticoid exposure on insulin signalling proteins in skeletal muscle of fetal sheep during late gestation. Experimental manipulation of fetal plasma glucocorticoid concentration was achieved by fetal cortisol infusion and maternal dexamethasone treatment. Cortisol infusion significantly increased muscle protein levels of Akt2 and phosphorylated Akt at Ser473, and decreased protein levels of phosphorylated forms of mTOR at Ser2448 and S6K at Thr389. Muscle GLUT4 protein expression was significantly higher in fetuses whose mothers were treated with dexamethasone compared to those treated with saline. There were no significant effects of glucocorticoid exposure on muscle protein abundance of IR-β, IGF-1R, PKCζ, Akt1, calpastatin or muscle glycogen content. The present study demonstrated that components of the insulin signalling pathway in skeletal muscle of the ovine fetus are influenced differentially by naturally occurring and synthetic glucocorticoids. These findings may provide a mechanism by which elevated concentrations of endogenous glucocorticoids retard fetal growth

The concentration of ¹⁴C-label (dpm/g tissue) in various fat depots (MAT, PAT, VAT and SAT) from lean mice (A) and obese mice (B).

<p>The total ¹⁴C-label content (dpm/total tissue) in various fat depots (MAT, PAT, VAT and SAT) from lean mice (C) and obese mice (D). Comparison of the total ¹⁴C-label content in adipose tissue (MAT+PAT+VAT+SAT) between lean and obese mice (E). The data are presented as the mean ± SEM (n = 3). Different letters indicate significant differences between different adipose depots at a particular time point (<i>P</i><0.05). Asterisks (*) indicate significant differences between lean and obese mice at a particular time point (<i>P</i><0.05). MAT, mesenteric adipose tissue, PAT, perirenal adipose tissue, VAT, visceral adipose tissue, SAT, subcutaneous adipose tissue.</p

Time course (0–168 h) of the ¹⁴C-label concentrations (dpm/g tissue and dpm/μl plasma) in plasma, skin, liver, muscle, adipose tissue, spleen, pancreas, heart, kidney, lung, stomach, intestine and brain from lean and obese mice after a single oral dose.

<p>The data are presented as the mean ± SEM (n = 3). Asterisks (*) indicate significant differences between lean and obese mice at a particular time point (<i>P</i><0.05). Muscle: all harvested muscles from the arms and legs as well as dorsal muscle. Adipose: subcutaneous, visceral, perirenal and mesenteric adipose tissue.</p

Comparative study of the mRNA expression of ACSL1, FAT, ACBP, FABP3, and FATP1 in the EDL, GAS and SOL between lean and obese mice.

<p>The data are presented as the mean ± SEM (n = 3). Asterisks (*) indicate significant differences between lean and obese mice (<i>P</i><0.05). ACSL, long-chain fatty acyl-CoA synthetase; FAT, fatty acid translocase; ACBP, acyl CoA binding protein; FABP, fatty acid binding protein; FATP, fatty acid transport protein, EDL, extensor digitorum longus; GAS, gastrocnemius; SOL, soleus.</p

Comparative study of the mRNA levels of ACSL1, FAT, ACBP, FABP3, and FATP1 in MAT, PAT, VAT and SAT between lean and obese mice.

<p>The data are presented as the mean ± SEM (n = 3). Asterisks (*) indicate significant differences between lean and obese mice (<i>P</i><0.05). ACSL, long-chain fatty acyl-CoA synthetase; FAT, fatty acid translocase; ACBP, acyl CoA binding protein; FABP, fatty acid binding protein; FATP, fatty acid transport protein.</p

The concentration of ¹⁴C-label (dpm/g tissue) in the EDL, GAS and SOL from lean mice (A) and obese mice (B).

<p>Comparative study of the ¹⁴C-label concentration (dpm/g tissue) in the EDL (C), GAS (D) and SOL (E) between lean and obese mice. The data are presented as the mean ± SEM (n = 3). Different letters indicate significant differences between different muscle types at a particular time point (<i>P</i> < 0.05). Asterisks (*) indicate significant differences between lean and obese mice at a particular time point (<i>P</i><0.05). EDL, extensor digitorum longus; GAS, gastrocnemius; SOL, soleus.</p

Alterations in Oral [1-¹⁴C] 18:1n-9 Distribution in Lean Wild-Type and Genetically Obese (<i>ob/ob</i>) Mice

<div><p>Obesity may result from altered fatty acid (FA) disposal. Altered FA distribution in obese individuals is poorly understood. Lean wild-type C57BL/6J and obese C57BL/6J^<i>ob/ob</i> mice received an oral dose of [1-¹⁴C]18:1n-9 (oleic acid), and the radioactivity in tissues was evaluated at various time points. The ¹⁴C concentration decreased rapidly in gastrointestinal tract but gradually increased and peaked at 96 h in adipose tissue, muscle and skin in lean mice. The ¹⁴C concentration was constant in adipose tissue and muscle of obese mice from 4h to 168h. ¹⁴C-label content in adipose tissue was significantly affected by genotype, whereas muscle ¹⁴C-label content was affected by genotype, time and the interaction between genotype and time. There was higher total ¹⁴C retention (47.7%) in obese mice than in lean mice (9.0%) at 168 h (<i>P</i><0.05). The ¹⁴C concentrations in the soleus and gastrocnemius muscle were higher in obese mice than in lean mice (<i>P</i><0.05). Perirenal adipose tissue contained the highest ¹⁴C content in lean mice, whereas subcutaneous adipose tissue (SAT) had the highest ¹⁴C content and accounted for the largest proportion of total radioactivity among fat depots in obese mice. More lipid radioactivity was recovered as TAG in SAT from obese mice than from lean mice (<i>P</i><0.05). Gene expression suggested acyl CoA binding protein and fatty acid binding protein are important for FA distribution in adipose tissue and muscle. The FA distribution in major tissues was altered in <i>ob/ob</i> mice, perhaps contributing to obesity. Understanding the disparity in FA disposal between lean and obese mice may reveal novel targets for the treatment and prevention of obesity.</p></div

Data_Sheet_1_Low-protein diets supplemented with glycine improves pig growth performance and meat quality: An untargeted metabolomic analysis.doc

For the purpose to improve meat quality, pigs were fed a normal diet (ND), a low protein diet (LPD) and a LPD supplemented with glycine (LPDG). Chemical and metabolomic analyses showed that LPD increased IMF deposition and the activities of GPa and PK, but decreased glycogen content, the activities of CS and CcO, and the abundance of acetyl-CoA, tyrosine and its metabolites in muscle. LPDG promoted muscle fiber transition from type II to type I, increased the synthesis of multiple nonessential amino acids, and pantothenic acid in muscle, which should contributed to the improved meat quality and growth rate. This study provides some new insight into the mechanism of diet induced alteration of animal growth performance and meat quality. In addition, the study shows that dietary supplementation of glycine to LPD could be used to improved meat quality without impairment of animal growth.</p