Maternal high fat diet induces early cardiac hypertrophy and alters cardiac metabolism in Sprague Dawley rat offspring.

BACKGROUND AND AIM: Maternal high fat diets (mHFD) have been associated with an increased offspring cardiovascular risk. Recently we found that the class IIa HDAC-MEF2 pathway regulates gene programs controlling fatty acid oxidation in striated muscle. This same pathway controls hypertrophic responses in the heart. We hypothesized that mHFD is associated with activation of signal controlling class II a HDAC activity and activation of genes involved in fatty acid oxidation and cardiac hypertrophy in offspring. METHODS AND RESULTS: Female Sprague Dawley rats were fed either normal fat diet (12%) or high fat diet (43%) three weeks prior to mating, remaining on diets until study completion. Hearts of postnatal day 1 (PN1) and PN10 pups were collected. Bioenergetics and respiration analyses were performed in neonatal ventricular cardiomyocytes (NVCM). In offspring exposed to mHFD, body weight was increased at PN10 accompanied by increased body fat percentage and blood glucose. Heart weight and heart weight to body weight ratio were increased at PN1 and PN10, and were associated with elevated signalling through the AMPK-class IIa HDAC-MEF2 axis. The expression of the MEF2-regulated hypertrophic markers ANP and BNP were increased as were expression of genes involved in fatty acid oxidation. However this was only accompanied by an increased protein expression of fatty acid oxidation enzymes at PN10. NVCM isolated from these pups exhibited increased glycolysis and an impaired substrate flexibility. CONCLUSION: Combined, these results suggest that mHFD induces signalling and transcriptional events indicative of reprogrammed cardiac metabolism and of cardiac hypertrophy in Sprague Dawley rat offspring.

Emerging roles for the amyloid precursor protein and derived peptides in the regulation of cellular and systemic metabolism.

The amyloid precursor protein (APP) is a transmembrane protein that can be cleaved by proteases through two different pathways to yield a number of small peptides, each with distinct physiological properties and functions. It has been extensively studied in the context of Alzheimer's disease, with the APP-derived amyloid ß (Aß) peptide being a major constituent of the amyloid plaques observed in this disease. It has been known for some time that APP can regulate neuronal metabolism; however, the present review examines the evidence indicating that APP and its peptides can also regulate key metabolic processes such as insulin action, lipid synthesis and storage and mitochondrial function in peripheral tissues. This review presents the hypothesis that amyloidogenic processing of APP in peripheral tissues plays a key role in the response to nutrient excess and that this could contribute to the pathogenesis of metabolic diseases such as obesity and type 2 diabetes (T2D).

N-Acetylcysteine improves mitochondrial function and ameliorates behavioral deficits in the R6/1 mouse model of Huntington's disease.

Huntington's disease (HD) is a neurodegenerative disorder, involving psychiatric, cognitive and motor symptoms, caused by a CAG-repeat expansion encoding an extended polyglutamine tract in the huntingtin protein. Oxidative stress and excitotoxicity have previously been implicated in the pathogenesis of HD. We hypothesized that N-acetylcysteine (NAC) may reduce both excitotoxicity and oxidative stress through its actions on glutamate reuptake and antioxidant capacity. The R6/1 transgenic mouse model of HD was used to investigate the effects of NAC on HD pathology. It was found that chronic NAC administration delayed the onset and progression of motor deficits in R6/1 mice, while having an antidepressant-like effect on both R6/1 and wild-type mice. A deficit in the astrocytic glutamate transporter protein, GLT-1, was found in R6/1 mice. However, this deficit was not ameliorated by NAC, implying that the therapeutic effect of NAC is not due to rescue of the GLT-1 deficit and associated glutamate-induced excitotoxicity. Assessment of mitochondrial function in the striatum and cortex revealed that R6/1 mice show reduced mitochondrial respiratory capacity specific to the striatum. This deficit was rescued by chronic treatment with NAC. There was a selective increase in markers of oxidative damage in mitochondria, which was rescued by NAC. In conclusion, NAC is able to delay the onset of motor deficits in the R6/1 model of Huntington's disease and it may do so by ameliorating mitochondrial dysfunction. Thus, NAC shows promise as a potential therapeutic agent in HD. Furthermore, our data suggest that NAC may also have broader antidepressant efficacy.

Age-related proteostasis and metabolic alterations in Caspase-2-deficient mice.

Ageing is a complex biological process for which underlying biochemical changes are still largely unknown. We performed comparative profiling of the cellular proteome and metabolome to understand the molecular basis of ageing in Caspase-2-deficient (Casp2(-/-)) mice that are a model of premature ageing in the absence of overt disease. Age-related changes were determined in the liver and serum of young (6-9 week) and aged (18-24 month) wild-type and Casp2(-/-) mice. We identified perturbed metabolic pathways, decreased levels of ribosomal and respiratory complex proteins and altered mitochondrial function that contribute to premature ageing in the Casp2(-/-) mice. We show that the metabolic profile changes in the young Casp2(-/-) mice resemble those found in aged wild-type mice. Intriguingly, aged Casp2(-/-) mice were found to have reduced blood glucose and improved glucose tolerance. These results demonstrate an important role for caspase-2 in regulating proteome and metabolome remodelling during ageing.

Differentiated mTOR but not AMPK signaling after strength vs endurance exercise in training-accustomed individuals.

The influence of adenosine mono phosphate (AMP)-activated protein kinase (AMPK) vs Akt-mammalian target of rapamycin C1 (mTORC1) protein signaling mechanisms on converting differentiated exercise into training specific adaptations is not well-established. To investigate this, human subjects were divided into endurance, strength, and non-exercise control groups. Data were obtained before and during post-exercise recovery from single-bout exercise, conducted with an exercise mode to which the exercise subjects were accustomed through 10 weeks of prior training. Blood and muscle samples were analyzed for plasma substrates and hormones and for muscle markers of AMPK and Akt-mTORC1 protein signaling. Increases in plasma glucose, insulin, growth hormone (GH), and insulin-like growth factor (IGF)-1, and in phosphorylated muscle phospho-Akt substrate (PAS) of 160 kDa, mTOR, 70 kDa ribosomal protein S6 kinase, eukaryotic initiation factor 4E, and glycogen synthase kinase 3a were observed after strength exercise. Increased phosphorylation of AMPK, histone deacetylase5 (HDAC5), cAMP response element-binding protein, and acetyl-CoA carboxylase (ACC) was observed after endurance exercise, but not differently from after strength exercise. No changes in protein phosphorylation were observed in non-exercise controls. Endurance training produced an increase in maximal oxygen uptake and a decrease in submaximal exercise heart rate, while strength training produced increases in muscle cross-sectional area and strength. No changes in basal levels of signaling proteins were observed in response to training. The results support that in training-accustomed individuals, mTORC1 signaling is preferentially activated after hypertrophy-inducing exercise, while AMPK signaling is less specific for differentiated exercise.

Dichloroacetate inhibits aerobic glycolysis in multiple myeloma cells and increases sensitivity to bortezomib.

BACKGROUND: Dichloroacetate (DCA), through the inhibition of aerobic glycolysis (the 'Warburg effect') and promotion of pyruvate oxidation, induces growth reduction in many tumours and is now undergoing several clinical trials. If aerobic glycolysis is active in multiple myeloma (MM) cells, it can be potentially targeted by DCA to induce myeloma growth inhibition. METHODS: Representative multiple myeloma cell lines and a myeloma-bearing mice were treated with DCA, alone and in combination with bortezomib. RESULTS: We found that aerobic glycolysis occurs in approximately half of MM cell lines examined, producing on average 1.86-fold more lactate than phorbol myristate acetate stimulated-peripheral blood mononuclear cells and is associated with low-oxidative capacity. Lower doses of DCA (5-10 mM) suppressed aerobic glycolysis and improved cellular respiration that was associated with activation of the pyruvate dehydrogenase complex. Higher doses of DCA (10-25 mM) induced superoxide production, apoptosis, suppressed proliferation with a G0/1 and G2M phase arrest in MM cell lines. In addition, DCA increased MM cell line sensitivity to bortezomib, and combinatorial treatment of both agents improved the survival of myeloma-bearing mice. CONCLUSION: Myeloma cells display aerobic glycolysis and DCA may complement clinically used MM therapies to inhibit disease progression.

Exercise increases skeletal muscle GLUT4 gene expression in patients with type 2 diabetes.

The aim of the study was to determine the effect of a single bout of exercise on GLUT4 gene expression in muscle of patients with type 2 diabetes (T2D) and control subjects, matched for age and body mass index. Nine patients with T2D and nine control subjects performed 60 min of cycling exercise at ~55% peak power (W(max) ). Skeletal muscle biopsies were obtained at baseline, immediately post and 3-h post exercise. GLUT4 mRNA expression increased (p < 0.05) to a similar extent immediately post exercise in control (~60%) and T2D (~66%) subjects, and remained elevated (p < 0.05) 3-h post exercise with no differences between groups. Similarly, p-AMP-activated protein kinase, p38 mitogen-activated kinase and proliferator-activated receptor gamma co-activator-alpha mRNA expression were increased (p < 0.05) post exercise, and were not different between the groups. In conclusion, a single bout of exercise increased skeletal muscle GLUT4 mRNA expression in patients with T2D to a similar extent as in control subjects.

Exercise training increases adipose tissue GLUT4 expression in patients with type 2 diabetes.

We investigated the effects of exercise training on adipose tissue and skeletal muscle GLUT4 expression in patients with type 2 diabetes (T2D). Muscle and adipose tissue samples were obtained before and after 4-weeks of exercise training in seven patients with T2D [47 ± 2 years, body mass index (BMI) 28 ± 2]. Seven control subjects (54 ± 4, BMI 30 ± 2) were recruited for baseline comparison. Adipose tissue GLUT4 protein expression was 43% lower (p < 0.05) in patients with T2D compared with control subjects and exercise training increased (p < 0.05) adipose tissue GLUT4 expression by 36%. Skeletal muscle GLUT4 protein expression was not different between control subjects and patients with T2D. Exercise training increased (p < 0.05) skeletal muscle GLUT4 protein expression by 20%. In conclusion, 4-weeks of exercise training increased GLUT4 expression in adipose tissue and skeletal muscle of patients with T2D, although the functional benefits of this adaptation appear to be dependent on an optimal ß-cell function.

Intravenous AICAR administration reduces hepatic glucose output and inhibits whole body lipolysis in type 2 diabetic patients.

AIMS/HYPOTHESIS: The 5'-AMP-activated protein kinase (AMPK) pathway is intact in type 2 diabetic patients and is seen as a target for diabetes treatment. In this study, we aimed to assess the impact of the AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR) on both glucose and fatty acid metabolism in vivo in type 2 diabetic patients. METHODS: Stable isotope methodology and blood and muscle biopsy sampling were applied to assess blood glucose and fatty acid kinetics following continuous i.v. infusion of AICAR (0.75 mg kg(-1) min(-1)) and/or NaCl (0.9%) in ten male type 2 diabetic patients (age 64 +/- 2 years; BMI 28 +/- 1 kg/m(2)). RESULTS: Plasma glucose rate of appearance (R (a)) was reduced following AICAR administration, while plasma glucose rate of disappearance (R (d)) was similar in the AICAR and control test. Consequently, blood glucose disposal (R (d) expressed as a percentage of R (a)) was increased following AICAR infusion (p < 0.001). Accordingly, a greater decline in plasma glucose concentration was observed following AICAR infusion (p < 0.001). Plasma NEFA R (a) and R (d) were both significantly reduced in response to AICAR infusion, and were accompanied by a significant decline in plasma NEFA concentration. Although AMPK phosphorylation in skeletal muscle was not increased, we observed a significant increase in acetyl-CoA carboxylase phosphorylation (p < 0.001). CONCLUSIONS/INTERPRETATION: The i.v. administration of AICAR reduces hepatic glucose output, thereby lowering blood glucose concentrations in vivo in type 2 diabetic patients. Furthermore, AICAR administration stimulates hepatic fatty acid oxidation and/or inhibits whole body lipolysis, thereby reducing plasma NEFA concentration.