Postnatal Consumption of Black Bean Powder Protects against Obesity and Dyslipidemia in Male Adult Rat Offspring from Obese Pregnancies.

The adverse influence of maternal obesity on offspring metabolic health throughout the life-course is a significant public health challenge with few effective interventions. We examined if black bean powder (BBP) supplementation to a high-calorie maternal pregnancy diet or a postnatal offspring diet could offer protection against the metabolic programming of metabolic disease risk in adult offspring. Female Sprague Dawley rats were randomly assigned to one of three diets (n = 10/group) for a 3-week pre-pregnancy period and throughout gestation and lactation: (i) a low-caloric control diet (CON); (ii) a high-caloric obesity-inducing diet (HC); or (iii) the HC diet with 20% black bean powder (HC-BBP). At weaning [postnatal day (PND) 21], one male pup from each dam was weaned onto the CON diet throughout the postnatal period until adulthood (PND120). In addition, a second male from the HC group only was weaned onto the CON diet supplemented with BBP (CON-BBP). Thus, based on the maternal diet exposure and offspring postnatal diet, four experimental adult offspring groups were compared: CON/CON, HC/CON, HC-BPP/CON, and HC/CON-BBP. On PND120, blood was collected for biochemical analysis (e.g., lipids, glycemic control endpoints, etc.), and livers were excised for lipid analysis (triglycerides [TG] and cholesterol) and the mRNA/protein expression of lipid-regulatory targets. Compared with the CON/CON group, adult offspring from the HC/CON group exhibited a higher (p < 0.05) body weight (BW) (682.88 ± 10.67 vs. 628.02 ± 16.61 g) and hepatic TG (29.55 ± 1.31 vs. 22.86 ± 1.85 mmol/g). Although maternal BBP supplementation (HC-BBP/CON) had little influence on metabolic outcomes, the consumption of BBP in the postnatal period (HC/CON-BBP) lowered hepatic TG and cholesterol compared with the other treatment groups. Reduced hepatic TG in the HC/CON-BBP was likely associated with lower postnatal BW gain (vs. HC/CON), lower mRNA and protein expression of hepatic Fasn (vs. HC/CON), and lower serum leptin concentration (vs. CON/CON and HC groups). Our results suggest that the postnatal consumption of a black-bean-powder-supplemented diet may protect male rat offspring against the programming of obesity and dyslipidemia associated with maternal obesity. Future work should investigate the bioactive fraction of BBP responsible for the observed effect.

Maternal Pea Protein Intake Provides Sex-Specific Protection against Dyslipidemia in Offspring from Obese Pregnancies.

Increased consumption of dietary pulse protein has been shown to assist in body weight regulation and improve a range of metabolic health outcomes. We investigated if the exchange of casein for yellow pea protein (YPPN) in an obese-inducing maternal diet throughout pregnancy and lactation offered protection against obesity and dyslipidemia in offspring. Sixty female Sprague Dawley rats were fed a low-calorie control diet (CON), a high-caloric obesity-inducing diet (with casein protein (CP), HC-CP), or an isocaloric/macronutrient-matched HC diet supplemented with YPPN isolate (HC-PPN) in pre-pregnancy, gestation, and lactation. Body weight (BW) and metabolic outcomes were assessed in male and female offspring at weaning and in adulthood after consuming the CON diet in the postnatal period. Consumption of the HC-PPN diet did not protect against maternal obesity but did improve reproductive success compared with the HC-CP group (72.7% versus 43.7%) and reduced total energy, fat, and protein in maternal milk. Male, but not female, offspring from mothers fed the HC-CP diet demonstrated hyperphagia, obesity, dyslipidemia, and hepatic triglyceride (TG) accumulation as adults compared with CON offspring. Isocaloric exchange of CP for YPPN in a high-calorie obese-inducing diet did not protect against obesity but did improve several aspects of lipid metabolism in adult male offspring including serum total cholesterol, LDL/VLDL cholesterol, triglycerides (TGs), and hepatic TG concentration. Our results suggest that the exchange of CP for YPPN in a maternal obese-inducing diet selectively protects male offspring from the malprogramming of lipid metabolism in adulthood.

Maternal pea fiber supplementation to a high calorie diet in obese pregnancies protects male offspring from metabolic dysfunction in adulthood.

We investigated the influence of maternal yellow-pea fiber supplementation in obese pregnancies on offspring metabolic health in adulthood. Sixty newly-weaned female Sprague-Dawley rats were randomized to either a low-calorie control diet (CON) or high calorie obesogenic diet (HC) for 6-weeks. Obese animals were then fed either the HC diet alone or the HC diet supplemented with yellow-pea fiber (HC + FBR) for an additional 4-weeks prior to breeding and throughout gestation and lactation. On postnatal day (PND) 21, 1 male and 1 female offspring from each dam were weaned onto the CON diet until adulthood (PND 120) for metabolic phenotyping. Adult male, but not female, HC offspring demonstrated increased body weight and feed intake vs CON offspring, however no protection was offered by maternal FBR supplementation. HC male and female adult offspring demonstrated increased serum glucose and insulin resistance (HOMA-IR) compared with CON offspring. Maternal FBR supplementation improved glycemic control in male, but not female offspring. Compared with CON offspring, male offspring from HC dams demonstrated marked dyslipidemia (higher serum cholesterol, increased number of TG-rich lipoproteins, and smaller LDL particles) which was largely normalized in offspring from HC + FBR mothers. Male offspring born to obese mothers (HC) had higher hepatic TG, which tended to be lowered (p = 0.07) by maternal FBR supplementation.Supplementation of a maternal high calorie diet with yellow-pea fiber in prepregnancy and throughout gestation and lactation protects male offspring from metabolic dysfunction in the absence of any change in body weight status in adulthood.

Gestational hypercholesterolemia programs hepatic steatosis in a sex-specific manner in ApoE-deficient mice.

Maternal hypercholesterolemia (MHC), a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during pregnancy, may influence offspring hepatic lipid metabolism and increase the risk of nonalcoholic fatty liver disease (NAFLD). As NAFLD is characterized by a sexual dimorphic response, we assessed whether early-life exposure to excessive cholesterol influences the development of NAFLD in offspring and whether this occurs in a sex-specific manner. Female apoE-/- mice were randomly assigned to a control (CON) or a high cholesterol (CH; 0.15%) diet prior to breeding. At parturition, a cross-fostering approach was used to establish three groups: (1) normal cholesterol exposure throughout gestation and lactation (CON-CON); (2) excessive cholesterol exposure throughout gestation and lactation (CH-CH); and (3) excessive cholesterol exposure in the gestation period only (CH-CON). Adult male offspring (PND 84) exposed to excessive cholesterol during gestation only (CH-CON) demonstrated hepatic triglyceride (TG) accumulation and reduced lipogenic gene expression. However, male mice with a prolonged cholesterol exposure throughout gestation and lactation (CH-CH) had a similar, but not exacerbated hepatic response. Further, with the exception of higher serum TG in adult CH-CH females, evidence for a programming effect in female offspring was largely absent in comparison with males. These results indicate a sexual dimorphic response with respect to the effect of MHC on later life hepatic steatosis and highlight the gestation period as the most influential malprogramming window for hepatic lipid dysfunction in males.

Reprogramming of aerobic glycolysis in non-transformed mouse liver with pyruvate dehydrogenase complex deficiency.

The Pyruvate Dehydrogenase Complex (PDC), a key enzyme in glucose metabolism, catalyzes an irreversible oxidative decarboxylation reaction of pyruvate to acetyl-CoA, linking the cytosolic glycolytic pathway to mitochondrial tricarboxylic acid cycle and oxidative phosphorylation. Earlier we reported a down-regulation of several key hepatic lipogenic enzymes and their upstream regulators in liver-specific PDC-deficient mouse (L-PDCKO model by deleting the Pdha1 gene). In this study we investigated gene expression profiles of key glycolytic enzymes and other proteins that respond to various metabolic stresses in liver from L-PDCKO mice. Transcripts of several, such as hexokinase 2, phosphoglycerate kinase 1, pyruvate kinase muscle-type 2, and lactate dehydrogenase B as well as those for the nonglycolysis-related proteins, CD-36, C/EBP homologous protein, and peroxisome proliferator-activated receptor γ, were up-regulated in L-PDCKO liver whereas hypoxia-induced factor-1α, pyruvate dehydrogenase kinase 1 and Sirtuin 1 transcripts were down-regulated. The protein levels of pyruvate kinase muscle-type 2 and lactate dehydrogenase B were increased whereas that of lactate dehydrogenase A was decreased in PDC-deficient mouse liver. Analysis of endoplasmic reticulum and oxidative stress indicators suggests that the L-PDCKO liver showed evidence of the former but not the latter. These findings indicate that (i) liver-specific PDC deficiency is sufficient to induce "aerobic glycolysis characteristic" in mouse liver, and (ii) the mechanism(s) responsible for these changes appears distinct from that which induces the Warburg effect in some cancer cells.

Excessive early-life cholesterol exposure may have later-life consequences for nonalcoholic fatty liver disease.

The in utero and immediate postnatal environments are recognized as critical windows of developmental plasticity where offspring are highly susceptible to changes in the maternal metabolic milieu. Maternal hypercholesterolemia (MHC) is a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during pregnancy which can program metabolic dysfunction in offspring, including dysregulation of hepatic lipid metabolism. Although there is currently no established reference range MHC, a loosely defined cutoff point for total cholesterol >280 mg/dL in the third trimester has been suggested. There are several unanswered questions regarding this condition particularly with regard to how the timing of cholesterol exposure influences hepatic lipid dysfunction and the mechanisms through which these adaptations manifest in adulthood. Gestational hypercholesterolemia increased fetal hepatic lipid concentrations and altered lipid regulatory mRNA and protein content. These early changes in hepatic lipid metabolism are evident in the postweaning environment and persist into adulthood. Further, changes to hepatic epigenetic signatures including microRNA (miR) and DNA methylation are observed in utero, at weaning, and are evident in adult offspring. In conclusion, early exposure to cholesterol during critical developmental periods can predispose offspring to the early development of nonalcoholic fatty liver disease (NAFLD) which is characterized by altered regulatory function beginning in utero and persisting throughout the life cycle.

Phenylbutyrate administration reduces changes in the cerebellar Purkinje cells population in PDC­deficient mice.

In humans, pyruvate dehydrogenase complex (PDC) deficiency impairs brain energy metabolism by reducing the availability of the functional acetyl­CoA pool. This "hypometabolic defect" results in congenital lactic acidosis and abnormalities of brain morphology and function, ranging from mild ataxia to profound psychomotor retardation. Our previous study showed reduction in total cell number and dendritic arbors in the cerebellar Purkinje cells in systemic PDC­deficient mice. Phenylbutyrate has been shown to increase PDC activity in cultured fibroblasts from PDC­deficient patients. Hence, we investigated the effects of postnatal (days 2­35) phenylbutyrate administration on the cerebellar Purkinje cell population in PDC­deficient female mice. Histological analyses of different regions of cerebellar cortex from the brain­specific PDC­deficient saline­injected mice revealed statistically significant reduction in the Purkinje cell density and increased cell size of the individual Purkinje cell soma compared to control PDC­normal, saline­injected group. Administration of phenylbutyrate to control mice did not cause significant changes in the Purkinje cell density and cell size in the studied regions. In contrast, administration of phenylbutyrate variably lessened the ill effects of PDC deficiency on Purkinje cell populations in different areas of the cerebellum. Our results lend further support for the possible use of phenylbutyrate as a potential treatment for PDC deficiency.

Maternal hypercholesterolemia programs dyslipidemia in adult male mouse progeny.

As a collection of metabolic abnormalities including inflammation, insulin resistance, hypertension, hormone imbalance, and dyslipidemia, maternal obesity has been well-documented to program disease risk in adult offspring. Although hypercholesterolemia is strongly associated with obesity, less work has examined the programming influence of maternal hypercholesterolemia (MHC) independent of maternal obesity or high-fat feeding. This study was conducted to characterize how MHC per se impacts lipid metabolism in offspring. Female (n = 6/group) C57BL/6J mice were randomly assigned to: (1.) a standard chow diet (Control, CON) or (2.) the CON diet supplemented with exogenous cholesterol (CH) (0.15%, w/w) throughout mating and the gestation and lactation periods. At weaning (postnatal day (PND) 21) and adulthood (PND 84), male offspring were characterized for blood lipid and lipoprotein profile and hepatic lipid endpoints, namely cholesterol and triglyceride (TG) accumulation, fatty acid profile, TG production, and mRNA expression of lipid-regulatory genes. Both newly weaned and adult offspring from CH mothers demonstrated increased very low-density lipoprotein (VLDL) particle number and size and hepatic TG and n-6 polyunsaturated fatty acid accumulation. Further, adult CH offspring exhibited reduced fatty acid synthase (Fasn) and increased diglyceride acyltransferase (Dgat1) mRNA expression. These programming effects appear to be independent of changes in hepatic TG production and postprandial lipid clearance. Study results suggest that MHC, independent of obesity or high-fat feeding, can induce early changes to serum VLDL distribution and hepatic lipid profile that persist into adulthood.

Gestational hypercholesterolemia alters fetal hepatic lipid metabolism and microRNA expression in Apo-E-deficient mice.

Maternal hypercholesterolemia (MHC) is a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during gestation, which can alter offspring hepatic lipid metabolism. However, the extent that these maladaptations occur during gestation and the molecular mechanisms involved remain unknown. MicoRNAs (miRNA) are small, noncoding RNAs that contribute to the development and progression of nonalcoholic fatty liver disease. Therefore, we sought to determine the degree to which in utero exposure to excessive cholesterol affects fetal hepatic lipid metabolism and miRNA expression. Twelve female apoE-/- mice were randomly assigned to two different chow-based diets throughout gestation: control (CON) or the CON diet with cholesterol (0.15%). MHC reduced maternal fecundity and reduced litter size and weight. On gestational day 18, fetuses from MHC dams possessed increased placental cholesterol and hepatic triglycerides (TG), which were accompanied by a downregulation in the expression of hepatic lipogenic and TG synthesis and transport genes. Furthermore, fetal livers from MHC mothers showed increased miRNA-27a and reduced miRNA-200c expression. In summary, in utero exposure to MHC alters fetal lipid metabolism and lends mechanistic insight that implicates early changes in miRNA expression that may link to later-life programming of disease risk.

Structural and Functional Analyses of the Human PDH Complex Suggest a "Division-of-Labor" Mechanism by Local E1 and E3 Clusters.

The pseudo-atomic structural model of human pyruvate dehydrogenase complex (PDHc) core composed of full-length E2 and E3BP components, calculated from our cryoelectron microscopy-derived density maps at 6-Å resolution, is similar to those of prokaryotic E2 structures. The spatial organization of human PDHc components as evidenced by negative-staining electron microscopy and native mass spectrometry is not homogeneous, and entails the unanticipated formation of local clusters of E1:E2 and E3BP:E3 complexes. Such uneven, clustered organization translates into specific duties for E1-E2 clusters (oxidative decarboxylation and acetyl transfer) and E3BP-E3 clusters (regeneration of reduced lipoamide) corresponding to half-reactions of the PDHc catalytic cycle. The addition of substrate coenzyme A modulates the conformational landscape of PDHc, in particular of the lipoyl domains, extending the postulated multiple random coupling mechanism. The conformational and associated chemical landscapes of PDHc are thus not determined entirely stochastically, but are restrained and channeled through an asymmetric architecture and further modulated by substrate binding.

Brain metabolism modulates neuronal excitability in a mouse model of pyruvate dehydrogenase deficiency.

Glucose is the ultimate substrate for most brain activities that use carbon, including synthesis of the neurotransmitters glutamate and γ-aminobutyric acid via mitochondrial tricarboxylic acid (TCA) cycle. Brain metabolism and neuronal excitability are thus interdependent. However, the principles that govern their relationship are not always intuitive because heritable defects of brain glucose metabolism are associated with the paradoxical coexistence, in the same individual, of episodic neuronal hyperexcitation (seizures) with reduced basal cerebral electrical activity. One such prototypic disorder is pyruvate dehydrogenase (PDH) deficiency (PDHD). PDH is central to metabolism because it steers most of the glucose-derived flux into the TCA cycle. To better understand the pathophysiology of PDHD, we generated mice with brain-specific reduced PDH activity that paralleled salient human disease features, including cerebral hypotrophy, decreased amplitude electroencephalogram (EEG), and epilepsy. The mice exhibited reductions in cerebral TCA cycle flux, glutamate content, spontaneous, and electrically evoked in vivo cortical field potentials and gamma EEG oscillation amplitude. Episodic decreases in gamma oscillations preceded most epileptiform discharges, facilitating their prediction. Fast-spiking neuron excitability was decreased in brain slices, contributing to in vivo action potential burst prolongation after whisker pad stimulation. These features were partially reversed after systemic administration of acetate, which augmented cerebral TCA cycle flux, glutamate-dependent synaptic transmission, inhibition and gamma oscillations, and reduced epileptiform discharge duration. Thus, our results suggest that dysfunctional excitability in PDHD is consequent to reduced oxidative flux, which leads to decreased neuronal activation and impaired inhibition, and can be mitigated by an alternative metabolic substrate.

Malprogramming of Hepatic Lipid Metabolism due to Excessive Early Cholesterol Exposure in Adult Progeny.

SCOPE: The programming of hepatic lipid dysfunction in response to early cholesterol exposure and the influencing effects of postnatal diet is evaluated in apoE-/- mice. METHODS AND RESULTS: In two separate studies, female mice are assigned to a standard chow (S) or a cholesterol-enriched chow (C) diet during gestation and lactation. Male offspring from each dam are weaned on a postnatal S or a hypercaloric western (W) diet resulting in four experimental groups: S-S and C-S (Experiment 1) and S-W and C-W (Experiment 2). At weaning, litters from hypercholesterolemic mothers weighed less (p < 0.05) and pups had higher blood lipids, glucose, and hepatic cholesterol compared with pups from S-fed mothers. Adult C-S offspring demonstrate an atherogenic lipid profile and increased (p < 0.05) hepatic cholesterol and triglyceride content with altered lipid regulatory mRNA expression and protein content compared with S-S offspring. Alternatively, no difference (p > 0.05) is observed between S-W and C-W in serum and hepatic lipid profiles; however, serum AST and ALT are higher (p < 0.05) in C-W versus S-W offspring. CONCLUSION: The degree of hepatic lipid deposition observed in adult offspring exposed to excessive early cholesterol is influenced by the postnatal diet.

Dichloroacetate Ameliorates Cardiac Dysfunction Caused by Ischemic Insults Through AMPK Signal Pathway-Not Only Shifts Metabolism.

Dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), regulates substrate metabolism in the heart. AMP-activated protein kinase (AMPK) is an age-related energy sensor that protects the heart from ischemic injury. This study aims to investigate whether DCA can protect the heart from ischemic injury through the AMPK signaling pathway. Young (3-4 months) and aged (20-24 months) male C57BL/6J mice were subjected to ligation of the left anterior descending coronary artery (LAD) for an in vivo ischemic model. The systolic function of the hearts was significantly decreased in both young and aged mice after 45 min of ischemia and 24 h of reperfusion. DCA treatment significantly improved cardiac function in both young and aged mice. The myocardial infarction analysis demonstrated that DCA treatment significantly reduced the infarction size caused by ischemia/reperfusion (I/R) in both young and aged mice. The isolated-cardiomyocyte experiments showed that DCA treatment ameliorated contractile dysfunction and improved the intracellular calcium signal of cardiomyocytes under hypoxia/reoxygenation (H/R) conditions. These cardioprotective functions of DCA can be attenuated by inhibiting AMPK activation. Furthermore, the metabolic measurements with an ex vivo working heart system demonstrated that the effects of DCA treatment on modulating the metabolic shift response to ischemia and reperfusion stress can be attenuated by inhibiting AMPK activity. The immunoblotting results showed that DCA treatment triggered cardiac AMPK signaling pathway by increasing the phosphorylation of AMPK's upstream kinase liver kinase B1 (LKB1) under both sham operations and I/R conditions. Thus, except from modulating metabolism in hearts, the cardioprotective function of DCA during I/R was mediated by the LKB1-AMPK pathway.

Defining the contribution of skeletal muscle pyruvate dehydrogenase α1 to exercise performance and insulin action.

The pyruvate dehydrogenase complex (PDC) converts pyruvate to acetyl-CoA and is an important control point for carbohydrate (CHO) oxidation. However, the importance of the PDC and CHO oxidation to muscle metabolism and exercise performance, particularly during prolonged or high-intensity exercise, has not been fully defined especially in mature skeletal muscle. To this end, we determined whether skeletal muscle-specific loss of pyruvate dehydrogenase alpha 1 ( Pdha1), which is a critical subunit of the PDC, impacts resting energy metabolism, exercise performance, or metabolic adaptation to high-fat diet (HFD) feeding. For this, we generated a tamoxifen (TMX)-inducible Pdha1 knockout (PDHmKO) mouse, in which PDC activity is temporally and specifically ablated in adult skeletal muscle. We assessed energy expenditure, ex vivo muscle contractile performance, and endurance exercise capacity in PDHmKO mice and wild-type (WT) littermates. Additionally, we studied glucose homeostasis and insulin sensitivity in muscle after 12 wk of HFD feeding. TMX administration largely ablated PDHα in skeletal muscle of adult PDHmKO mice but did not impact energy expenditure, muscle contractile function, or low-intensity exercise performance. Additionally, there were no differences in muscle insulin sensitivity or body composition in PDHmKO mice fed a control or HFD, as compared with WT mice. However, exercise capacity during high-intensity exercise was severely impaired in PDHmKO mice, in parallel with a large increase in plasma lactate concentration. In conclusion, although skeletal muscle PDC is not a major contributor to resting energy expenditure or long-duration, low-intensity exercise performance, it is necessary for optimal performance during high-intensity exercise.

Pyruvate dehydrogenase complex deficiency is linked to regulatory loop disorder in the αV138M variant of human pyruvate dehydrogenase.

The pyruvate dehydrogenase multienzyme complex (PDHc) connects glycolysis to the tricarboxylic acid cycle by producing acetyl-CoA via the decarboxylation of pyruvate. Because of its pivotal role in glucose metabolism, this complex is closely regulated in mammals by reversible phosphorylation, the modulation of which is of interest in treating cancer, diabetes, and obesity. Mutations such as that leading to the αV138M variant in pyruvate dehydrogenase, the pyruvate-decarboxylating PDHc E1 component, can result in PDHc deficiency, an inborn error of metabolism that results in an array of symptoms such as lactic acidosis, progressive cognitive and neuromuscular deficits, and even death in infancy or childhood. Here we present an analysis of two X-ray crystal structures at 2.7-Å resolution, the first of the disease-associated human αV138M E1 variant and the second of human wildtype (WT) E1 with a bound adduct of its coenzyme thiamin diphosphate and the substrate analogue acetylphosphinate. The structures provide support for the role of regulatory loop disorder in E1 inactivation, and the αV138M variant structure also reveals that altered coenzyme binding can result in such disorder even in the absence of phosphorylation. Specifically, both E1 phosphorylation at αSer-264 and the αV138M substitution result in disordered loops that are not optimally oriented or available to efficiently bind the lipoyl domain of PDHc E2. Combined with an analysis of αV138M activity, these results underscore the general connection between regulatory loop disorder and loss of E1 catalytic efficiency.

Maternal hypercholesterolemia enhances oxysterol concentration in mothers and newly weaned offspring but is attenuated by maternal phytosterol supplementation.

In hypercholesterolemic pregnancies, the maternal environment is characterized by excessive levels of atherogenic lipids that may increase cardiovascular disease risk in mothers and their offspring. We examined the influence of maternal hypercholesterolemia and phytosterol (PS) intervention on the concentration and metabolism of oxysterols, bioactive oxygenated cholesterol derivatives that regulate arterial health and lesion progression, in mothers and their newly weaned offspring. Twenty-one female apoE-/- mice were randomly assigned to three different diets throughout gestation and lactation: (1) chow, (2) high cholesterol (CH; 0.15%) and (3) CH with added PS (2%, CH/PS). At the end of the lactation period, mothers and pups were euthanized for serum and hepatic oxysterol analyses, hepatic transcriptional profiling of hepatic sterol regulatory targets and atherosclerosis. Hypercholesterolemic dams and their pups demonstrated increased (P˂.05) serum oxysterols [including 24 hydroxycholesterol (HC), 25HC, 27HC, 7αHC, 7ßHC and 7 ketocholesterol)] compared with the chow group that were normalized by maternal PS supplementation. Hepatic oxysterol concentrations followed a similar pattern of response in mothers but were not altered in newly weaned pups. Hepatic mRNA expression suggested a pattern of enhanced abca1/g1 high-density-lipoprotein-mediated efflux but a reduction in biliary abcg5/g8 export in both dams and their pups. Although arterial lesions were not apparent in newly weaned pups, CH dams demonstrated enhanced atherosclerosis that was reduced upon PS intervention. These results demonstrate that offspring from hypercholesterolemic pregnancies have enhanced circulating oxysterol concentrations and highlight the potential utility of PS as a lipid-lowering option during hypercholesterolemic pregnancies for which there are currently limited options.

Transcriptional control of enterohepatic lipid regulatory targets in response to early cholesterol and phytosterol exposure in apoE-/- mice.

OBJECTIVE: An excessive rise in blood lipids during pregnancy may promote metabolic dysfunction in adult progeny. We characterized how maternal phytosterol (PS) supplementation affected serum lipids and the expression of lipid-regulatory genes in the intestine and liver of newly-weaned apo-E deficient offspring from dams fed a chow diet supplemented with cholesterol (0.15%, CH) or cholesterol and PS (2%) (CH/PS) throughout pregnancy and lactation. RESULTS: Serum lipid concentrations and lipoprotein particle numbers were exacerbated in offspring from cholesterol-supplemented mothers but normalized to chow-fed levels in pups exposed to PS through the maternal diet during gestation and lactation. Compared with the CH pups, pups from PS-supplemented mothers demonstrated higher (p < 0.05) expression of the primary intestinal cholesterol transport protein (Niemann-Pick C1-like 1) and the rate-limiting enzyme in hepatic cholesterol synthesis (HMG-CoAr), suggestive of a compensatory response to restore cholesterol balance. Furthermore, pups from PS-supplemented mothers exhibited a coordinated downregulation (p < 0.05) of several genes regulating fatty acid synthesis including PGC1ß, SREBP1c, FAS, and ACC compared with the CH group. These results suggest that maternal PS supplementation during hypercholesterolemic pregnancies protects against aberrant lipid responses in newly-weaned offspring and results in differential regulation of cholesterol and lipid regulatory targets within the enterohepatic loop.

Genetic Dissociation of Glycolysis and the TCA Cycle Affects Neither Normal nor Neoplastic Proliferation.

Rapidly proliferating cells increase glycolysis at the expense of oxidative phosphorylation (oxphos) to generate sufficient levels of glycolytic intermediates for use as anabolic substrates. The pyruvate dehydrogenase complex (PDC) is a critical mitochondrial enzyme that catalyzes pyruvate's conversion to acetyl coenzyme A (AcCoA), thereby connecting these two pathways in response to complex energetic, enzymatic, and metabolic cues. Here we utilized a mouse model of hepatocyte-specific PDC inactivation to determine the need for this metabolic link during normal hepatocyte regeneration and malignant transformation. In PDC "knockout" (KO) animals, the long-term regenerative potential of hepatocytes was unimpaired, and growth of aggressive experimental hepatoblastomas was only modestly slowed in the face of 80%-90% reductions in AcCoA and significant alterations in the levels of key tricarboxylic acid (TCA) cycle intermediates and amino acids. Overall, oxphos activity in KO livers and hepatoblastoma was comparable with that of control counterparts, with evidence that metabolic substrate abnormalities were compensated for by increased mitochondrial mass. These findings demonstrate that the biochemical link between glycolysis and the TCA cycle can be completely severed without affecting normal or neoplastic proliferation, even under the most demanding circumstances. Cancer Res; 77(21); 5795-807. ©2017 AACR.

Acetyl-CoA production from pyruvate is not necessary for preservation of myelin.

Oligodendrocytes and Schwann cells not only form myelin in the central and peripheral nervous system, but also provide metabolic and trophic support to the axons they ensheathe. Acetyl-CoA is potentially a key molecule in Schwann cells and oligodendrocytes because it is at the crossroads of cellular lipid biosynthesis and energy generation. The main route for acetyl-CoA production is the oxidation of pyruvate by the pyruvate dehydrogenase complex (PDC). PDC deficiency in humans results in neurodegeneration and developmental impairments in both white and gray matter structures. To address the importance of PDC in myelinating glia, we deleted Pdha1 gene specifically in oligodendrocytes and Schwann cells. Surprisingly, sciatic and optic nerve morphology and the motor performance of Pdha1f/Y; CnpCre/+ mice are undistinguishable from those of controls at 1 month of age. In addition, myelin is stably maintained for at least 10 months. However, Pdha1f/Y; CnpCre/+ mice showed reduced fiber density and signs of axonal degeneration in both sciatic and optic nerves from 6 months of age. In contrast, 10 month-old mice bearing a floxed Pdha1 gene with either P0-Cre (expressed only by Schwann cells) or NG2-CreER (expressed in oligodendrocyte precursor cells) do not show any sign of axonal pathology or alterations in myelin structure or thickness. This indicates that the axonopathy is specific to the Pdha1f/Y; CnpCre/+ mice. Taken together, these results suggest that acetyl-CoA derived from pyruvate is not necessary for myelin maintenance and, thus, myelin-forming cells are not likely to contribute to the pathophysiology of PDC deficiency.