Choline supplementation restores substrate balance and alleviates complications of Pcyt2 deficiency

PCYT2 deficiency in Saarlooswolfdogs with progressive retinal, central, and peripheral neurodegeneration

We investigated a syndromic disease comprising blindness and neurodegeneration in 11 Saarlooswolfdogs. Clinical signs involved early adult onset retinal degeneration and adult-onset neurological deficits including gait abnormalities, hind limb weakness, tremors, ataxia, cognitive decline and behavioral changes such as aggression towards the owner. Histopathology in one affected dog demonstrated cataract, retinal degeneration, central and peripheral axonal degeneration, and severe astroglial hypertrophy and hyperplasia in the central nervous system. Pedigrees indicated autosomal recessive inheritance. We mapped the suspected genetic defect to a 15 Mb critical interval by combined linkage and autozygosity analysis. Whole genome sequencing revealed a private homozygous missense variant, PCYT2:c.4A>G, predicted to change the second amino acid of the encoded ethanolamine-phosphate cytidylyltransferase 2, XP_038402224.1:(p.Ile2Val). Genotyping of additional Saarlooswolfdogs confirmed the homozygous genotype in all eleven affected dogs and demonstrated an allele frequency of 9.9% in the population. This experiment also identified three additional homozygous mutant young dogs without overt clinical signs. Subsequent examination of one of these dogs revealed early-stage progressive retinal atrophy (PRA) and expansion of subarachnoid CSF spaces in MRI. Dogs homozygous for the pathogenic variant showed ether lipid accumulation, confirming a functional PCYT2 deficiency. The clinical and metabolic phenotype in affected dogs shows some parallels with human patients, in whom PCYT2 variants lead to a rare form of spastic paraplegia or axonal motor and sensory polyneuropathy. Our results demonstrate that PCYT2:c.4A>G in dogs cause PCYT2 deficiency. This canine model with histopathologically documented retinal, central, and peripheral neurodegeneration further deepens the knowledge of PCYT2 deficiency.

Serum metabolomic analysis of the dose-response effect of dietary choline in overweight male cats fed at maintenance energy requirements

Choline participates in methyl group metabolism and has been recognized for its roles in lipid metabolism, hepatic health and muscle function in various species. Data regarding the impacts of choline on feline metabolic pathways are scarce. The present study investigated how choline intake affects the metabolomic profile of overweight cats fed at maintenance energy. Overweight (n = 14; body condition score:6-8/9) male adult cats were supplemented with five doses of choline in a 5x5 Latin Square design. Cats received a daily dose of choline on extruded food (3620 mg choline/kg diet) for three weeks at maintenance energy requirements (130 kcal/kgBW0.4). Doses were based on body weight (BW) and the daily recommended allowance (RA) for choline for adult cats (63 mg/kg BW0.67). Treatment groups included: Control (no additional choline, 1.2 x NRC RA, 77 mg/kg BW0.67), 2 x NRC RA (126 mg/kg BW0.67), 4 x NRC RA (252 mg/kg BW0.67), 6 x RA (378 mg/kg BW0.67), and 8 x NRC RA (504 mg/kg BW0.67). Serum was collected after an overnight fast at the end of each treatment period and analyzed for metabolomic parameters through nuclear magnetic resonance (NMR) spectroscopy and direct infusion mass spectrometry (DI-MS). Data were analyzed using GLIMMIX, with group and period as random effects, and dose as the fixed effect. Choline up to 8 x NRC RA was well-tolerated. Choline at 6 and 8 x NRC RA resulted in greater concentrations of amino acids and one-carbon metabolites (P < 0.05) betaine, dimethylglycine and methionine. Choline at 6 x NRC RA also resulted in greater phosphatidylcholine and sphingomyelin concentrations (P < 0.05). Supplemental dietary choline may be beneficial for maintaining hepatic health in overweight cats, as it may increase hepatic fat mobilization and methyl donor status. Choline may also improve lean muscle mass in cats. More research is needed to quantify how choline impacts body composition.

Circulating direct infusion MS and NMR metabolomic profiles of post-gonadectomy kittens with or without additional dietary choline supplementation

Choline is beneficial for energy metabolism and growth in various species. Choline may work similarly in kittens at risk of obesity. Direct infusion MS (Di-MS) and NMR spectroscopy were used to investigate the metabolomic signatures of kittens supplemented with or without additional dietary choline for 12 weeks. Fifteen intact male kittens consumed a base diet (3310 mg choline/kg DM) to their daily metabolisable energy requirement (DER) over an 11-week acclimation. Kittens were gonadectomised and assigned, based on body weight, to the base diet (CONTROL, n 7) or the base diet with 300 mg/kgBW0·75 additional choline as choline chloride (CHOLINE, n 8) and offered three times their individual energy requirement divided into three meals. At weeks −1 and 12, fasted blood was sampled and serum analysed for 130 metabolites via Di-MS and fifty-one metabolites via NMR spectroscopy. Changes in fasted metabolites were assessed using a repeated-measures GLIMMIX procedure with time and group as fixed effects, and time as a repeated measure. Metabolites of one-carbon metabolism and lipids increased, and medium-chain acyl carnitines decreased from week −1 to 12 for CHOLINE (P < 0·05), but not CONTROL (P > 0·05). Increases in amino acid, biogenic amine and organic compound concentrations were observed in both groups (P < 0·05). The results suggest impacts of dietary choline at greater intakes than currently recommended on one-carbon metabolism and fatty acid oxidation, and these may promote healthy growth in post-gonadectomy kittens.

The emerging roles of PHOSPHO1 and its regulated phospholipid homeostasis in metabolic disorders

Emerging evidence suggests that phosphoethanolamine/phosphocholine phosphatase 1 (PHOSPHO1), a specific phosphoethanolamine and phosphocholine phosphatase, is involved in energy metabolism. In this review, we describe the structure and regulation of PHOSPHO1, as well as current knowledge about the role of PHOSPHO1 and its related phospholipid metabolites in regulating energy metabolism. We also examine mechanistic evidence of PHOSPHO1- and phospholipid-mediated regulation of mitochondrial and lipid droplets functions in the context of metabolic homeostasis, which could be potentially targeted for treating metabolic disorders.

Dose-response relationship between dietary choline and serum lipid profile, energy expenditure, and respiratory quotient in overweight adult cats fed at maintenance energy requirements

Choline is an essential nutrient linked to hepatic lipid metabolism in many animal species, including cats. The current study investigated the serum lipid profiles, serum liver enzymes, respiratory quotients, and energy expenditures of overweight cats fed maintenance diets, in response to graded doses of supplemental dietary choline. Overweight (body condition score [BCS]: ≥6/9) adult male neutered cats (n = 14) were supplemented with five choline chloride doses for 3-wk periods, in a 5 × 5 Latin square design. Doses were based on individual body weight (BW) and the daily recommended allowance (RA) for choline (63 mg/kg BW0.67) according to the National Research Council. Doses were control (no additional choline: 1.2 × RA, 77 mg/kg BW0.67), 2 × RA (126 mg/kg BW0.67), 4 × RA (252 mg/kg BW0.67), 6 × RA (378 mg/kg BW0.67), and 8 × RA (504 mg/kg BW0.67). Choline was top-dressed over the commercial extruded cat food (3,620 mg choline/kg diet), fed once a day at maintenance energy requirements (130 kcal/kgBW0.4). Body weight and BCS were assessed weekly. Fasted blood samples were taken and indirect calorimetry was performed at the end of each 3-wk period. Serum was analyzed for cholesterol, high-density lipoprotein cholesterol (HDL-C), triglycerides, non-esterified fatty acids, glucose, creatinine, blood urea nitrogen (BUN), alkaline phosphatase (ALP), and alanine aminotransferase. Very low-density lipoprotein cholesterol (VLDL) and low-density lipoprotein cholesterol were calculated. Data were analyzed via SAS using proc GLIMMIX, with group and period as the random effects, and treatment as the fixed effect. Statistical significance was considered at P < 0.05. Body weight and BCS did not change (P > 0.05). Serum cholesterol, HDL-C, triglycerides, and VLDL increased with 6 × RA (P < 0.05). Serum ALP decreased with 8 × RA (P = 0.004). Choline at 4 × and 6 × RA decreased serum BUN (P = 0.006). Fed or fasted respiratory quotient and energy expenditure did not differ among dietary choline doses (P > 0.05). These results suggest that dietary choline supplementation at 6 × RA may increase hepatic fat mobilization through increased lipoprotein transport and beneficially support hepatic health in overweight cats. Future studies that combine these results with existing knowledge of feline weight loss and hepatic lipidosis are warranted.

Mechanism of action and therapeutic route for a muscular dystrophy caused by a genetic defect in lipid metabolism

CHKB encodes one of two mammalian choline kinase enzymes that catalyze the first step in the synthesis of the membrane phospholipid phosphatidylcholine. In humans and mice, inactivation of the CHKB gene (Chkb in mice) causes a recessive rostral-to-caudal muscular dystrophy. Using Chkb knockout mice, we reveal that at no stage of the disease is phosphatidylcholine level significantly altered. We observe that in affected muscle a temporal change in lipid metabolism occurs with an initial inability to utilize fatty acids for energy via mitochondrial β-oxidation resulting in shunting of fatty acids into triacyglycerol as the disease progresses. There is a decrease in peroxisome proliferator-activated receptors and target gene expression specific to Chkb^−/− affected muscle. Treatment of Chkb^−/− myocytes with peroxisome proliferator-activated receptor agonists enables fatty acids to be used for β-oxidation and prevents triacyglyerol accumulation, while simultaneously increasing expression of the compensatory choline kinase alpha (Chka) isoform, preventing muscle cell injury.

Mutations in the CHKB gene cause muscular dystrophy. Here, the authors show that in mouse models of the disease changes in lipid metabolism are associated with decreased PPAR signaling, and show PPAR agonists can rescue expression of injury markers in myocytes in vitro.

Dietary choline in gonadectomized kittens improved food intake and body composition but not satiety, serum lipids, or energy expenditure

Gonadectomy is a major risk factor for feline obesity. The lipotropic effects of choline have demonstrated benefits for growth and carcass composition in livestock. The consumption of supplemental choline on body weight (BW), body composition, lipid metabolism, energy expenditure (EE), and serum satiety hormones were evaluated in 15 gonadectomized male kittens. Kittens were offered a base diet formulated for growth (3310mg choline/kg dry matter [DM]) to daily energy requirements (DER) over an 11-week acclimation. Post-gonadectomy, kittens were assigned to a base diet (CONTROL, n = 7) or choline group (base diet with additional choline at 300mg/kg BW^0.75 as a top dress) (CHOLINE, n = 8). For 12-weeks post-neuter, kittens were offered three times their DER over three meals to mimic ad libitum feeding. At week -1 and 12, body composition was assessed using dual energy x-ray absorptiometry (DXA), 24-hour indirect calorimetry was performed for EE and respiratory quotients (RQ), and fasted serum samples were analyzed for lipid compounds and satiety hormones. Daily food intake (FI) and weekly BW were measured. Data was analyzed as a repeated measures of variance (ANCOVA) using the GLIMMIX procedure with time and group as fixed effects. CHOLINE had lower mean daily FI and lower rates of BW accretion (P<0.05) in contrast to CONTROL. All absolute body composition data increased over time for both groups, with lower increases in total tissue mass (P = 0.031) and fat mass (P = 0.005) in CHOLINE. Serum satiety hormones and lipid compounds did not differ (P>0.05) between groups, but both groups experienced a decrease in low-density lipoproteins and increase in high-density lipoproteins (P<0.05). Primary substrate utilization showed lipid use when fasted and use of protein or mixed macronutrients in the fed state. Fed state EE decreased post-gonadectomy (P = 0.004), however, CHOLINE did not affect total EE or RQ. These results suggest that supplemental dietary choline reduces FI, BW, and fat mass and may help to reduce the propensity of weight gain and subsequent obesity in gonadectomized feline populations.

Linseed, Baru, and Coconut Oils: NMR-Based Metabolomics, Leukocyte Infiltration Potential In Vivo, and Their Oil Characterization. Are There Still Controversies?

Different fatty acid proportions produce potential inflammatory and metabolic changes in organisms. However, the evidence for how each fatty acid mediates the metabolic pathway, and its lipid stability remains controversial. To resolve this controversy, the present study investigated the metabolic effects of cold-pressed linseed (LG), coconut (CG), and baru (BG) oils in comparison to those of soybean oil (SG) in mice, in terms of their oil characterization and stability. The quality analysis showed less oxidative behavior among PUFA-rich oils (SO, BO, and LO, with induction periods lower than 2 h compared to 39.8 h for CG), besides the high contents of tocopherols and carotenoids in SG and LG. In the experimental study, CG presented higher triglyceride (257.93 ± 72.30) and VLDL-cholesterol levels (51.59 ± 14.46, p < 0.05), while LG reduced LDL levels (59.29 ± 7.56, p < 0.05) when compared to SG (183.14 ± 22.06, 36.63 ± 4.41 and 131.63 ± 29.0, respectively). For visceral fats, the adiposity index was lower for BG (7.32 ± 3.13) and CG (9.58 ± 1.02, p < 0.05) in relation to SG (12.53 ± 2.80), and for leukocyte recruitment, CG presented lower polymorphonuclear (PMN) (p < 0.0001) and mononuclear (MN) (p < 0.05) cell infiltration, demonstrating anti-inflammatory potential. In NMR-based metabolomics, although CG presented higher values for the glucose, lactate, and LDL/VLDL ratio, this group also evidenced high levels of choline, a lipotropic metabolite. Our study emphasized the controversies of saturated fatty acids, which impair serum lipids, while alfa-linolenic acid presented cardioprotective effects. However, coconut oil also has a positive immunomodulatory pathway and was found to reduce visceral bodyfat in mice. Therefore, for future applications, we suggest a combination of lauric and al-fa-linolenic acid sources, which are present in coconut and linseed oil, respectively. This combination could be less obesogenic and inflammatory and exert cardioprotective action.

Pcyt2 deficiency causes age-dependant development of nonalcoholic steatohepatitis and insulin resistance that could be attenuated with phosphoethanolamine

The mechanisms of NASH development in the context of age and genetics are not fully elucidated. This study investigates the age-dependent liver defects during NASH development in mice with heterozygous deletion of Pcyt2 (Pcyt2^+/−), the rate limiting enzyme in phosphatidylethanolamine (PE) synthesis. Further, the therapeutic potential of Pcyt2 substrate, phosphoethanolamine (PEtn), is examined. Pcyt2^+/− were investigated at 2 and 6–8 months (mo) of age and in addition, 6-mo old Pcyt2^+/− with developed NASH were supplemented with PEtn for 8 weeks and glucose and fatty acid metabolism, insulin signaling, and inflammation were examined. Heterozygous ablation of Pcyt2 causes changes in liver metabolic regulators from young age, prior to the development of liver disease which does not occur until adulthood. Only older Pcyt2^+/− experiences perturbed glucose and fatty acid metabolism. Older Pcyt2^+/− liver develops NASH characterized by increased glucose production, accumulation of TAG and glycogen, and increased inflammation. Supplementation with PEtn reverses Pcyt2^+/− steatosis, inflammation, and other aspects of NASH, showing that was directly caused by Pcyt2 deficiency. Pcyt2 deficiency is a novel mechanism of metabolic dysregulation due to reduced membrane ethanolamine phospholipid synthesis, and the metabolite PEtn offers therapeutic potential for NASH reversion.

Optimal Dietary Intake Composition of Choline and Betaine Is Associated with Minimized Visceral Obesity-Related Hepatic Steatosis in a Case-Control Study

Few studies on humans have comprehensively evaluated the intake composition of methyl-donor nutrients (MDNs: choline, betaine, and folate) in relation to visceral obesity (VOB)-related hepatic steatosis (HS), the hallmark of non-alcoholic fatty liver diseases. In this case-control study, we recruited 105 patients with HS and 104 without HS (controls). HS was diagnosed through ultrasound examination. VOB was measured using a whole-body analyzer. MDN intake was assessed using a validated quantitative food frequency questionnaire. After adjustment for multiple HS risk factors, total choline intake was the most significant dietary determinant of HS in patients with VOB (Beta: -0.41, p = 0.01). Low intake of choline (<6.9 mg/kg body weight), betaine (<3.1 mg/kg body weight), and folate (<8.8 μg/kg body weight) predicted increased odds ratios (ORs) of VOB-related HS (choline: OR: 22, 95% confidence interval [CI]: 6.5-80; betaine: OR: 14, 95% CI: 4.4-50; and folate: OR: 19, 95% CI: 5.2-74). Combined high intake of choline and betaine, but not folate, was associated with an 81% reduction in VOB-related HS (OR: 0.19, 95% CI: 0.05-0.69). Our data suggest that the optimal intake of choline and betaine can minimize the risk of VOB-related HS in a threshold-dependent manner.

Serum Lipid, Amino Acid and Acylcarnitine Profiles of Obese Cats Supplemented with Dietary Choline and Fed to Maintenance Energy Requirements

Obesity is a health concern for domestic cats. Obesity and severe energy restriction predispose cats to feline hepatic lipidosis. As choline is linked to lipid metabolism, we hypothesized that dietary choline supplementation would assist in reducing hepatic fat through increased lipoprotein transport and fatty acid oxidation. Twelve obese cats (body condition score [BCS] ≥ 8/9) were split into two groups. Cats were fed a control (n = 6; 4587 mg choline/kg dry matter [DM]) or a high choline diet (n = 6; 18,957 mg choline/kg DM) for 5 weeks, for adult maintenance. On days 0 and 35, fasted blood was collected, and the body composition was assessed. Serum lipoprotein and biochemistry profiles, plasma amino acids and plasma acylcarnitines were analyzed. The body weight, BCS and body composition were unaffected (p > 0.05). Choline increased the serum cholesterol, triacylglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol and plasma methionine (p < 0.05) and decreased the serum blood urea nitrogen and alkaline phosphatase (p < 0.05). Choline also reduced the plasma acylcarnitine to free carnitine ratio (p = 0.006). Choline may assist in eliminating hepatic fat through increased fat mobilization and enhanced methionine recycling.

CRTC3 Regulates the Lipid Metabolism and Adipogenic Differentiation of Porcine Intramuscular and Subcutaneous Adipocytes by Activating the Calcium Pathway

Fat deposition, especially the intramuscular (IM) fat deposition, is directly associated with meat quality. The cyclic adenosine monophosphate (cAMP)-responsive element binding-protein (CREB)-regulated transcription coactivator 3 (CRTC3) plays an important role in energy metabolism and various biological processes. The expression of porcine CRTC3 in skeletal muscle is positively associated with intramuscular fat deposition and possesses the capacity to control the intramuscular (IM) adipocyte morphology. However, the metabolic effects and transcriptional mechanism of CRTC3 in porcine intramuscular (IM) adipocytes as well as the regulatory mechanism of CRTC3 on porcine adipocyte differentiation have not been studied. Here, we utilized metabolomics and RNA sequencing (RNA-seq) to determine the metabolic and transcriptome profiles of CRTC3-overexpressing IM adipocytes. Moreover, the effect and regulation mechanism of CRTC3 on porcine IM and subcutaneous (SC) adipocyte differentiation were also studied. Our results showed that CRTC3 overexpression dramatically altered the metabolites in IM adipocytes. Glycerophospholipid (GP) metabolism and related genes were significantly changed in CRTC3-overexpressing IM adipocytes. Moreover, we demonstrated that CRTC3 overexpression promotes adipogenic differentiation by upregulating the Ca²⁺-cAMP signaling pathway in IM and SC adipocytes. We showed alterations in metabolites and in the expression of genes involved in lipid metabolism in CRTC3-overexpressing adipocytes and demonstrated the regulatory mechanism of CRTC3 on the adipogenic differentiation of porcine adipocytes. These results provide new insights into the regulatory roles of CRTC3 in porcine adipocytes, which could be an important target to regulate fat deposition in animals.

Choline transporter-like proteins 1 and 2 are newly identified plasma membrane and mitochondrial ethanolamine transporters

The membrane phospholipids phosphatidylcholine and phosphatidylethanolamine (PE) are synthesized de novo by the CDP-choline and CDP-ethanolamine (Kennedy) pathway, in which the extracellular substrates choline and ethanolamine are transported into the cell, phosphorylated, and coupled with diacylglycerol to form the final phospholipid product. Although multiple transport systems have been established for choline, ethanolamine transport is poorly characterized and there is no single protein assigned a transport function for ethanolamine. The solute carriers 44A (SLC44A) known as choline transporter-like proteins-1 and -2 (CTL1 and CTL2) are choline transporter at the plasma membrane and mitochondria. We report a novel function of CTL1 and CTL2 in ethanolamine transport. Using the lack or the gain of gene function in combination with specific antibodies and transport inhibitors we established two distinct ethanolamine transport systems of a high affinity, mediated by CTL1, and of a low affinity, mediated by CTL2. Both transporters are Na⁺-independent ethanolamine/H⁺ antiporters. Primary human fibroblasts with separate frameshift mutations in the CTL1 gene (M1= SLC44A1^ΔAsp517 and M2= SLC44A1^ΔSer126) are devoid of CTL1 ethanolamine transport but maintain unaffected CTL2 transport. The lack of CTL1 in M2 cells reduced the ethanolamine transport, the flux through the CDP-ethanolamine Kennedy pathway, and PE synthesis. In contrast, overexpression of CTL1 in M2 cells improved ethanolamine transport and PE synthesis. These data firmly establish that CTL1 and CTL2 are the first identified ethanolamine transporters in whole cells and mitochondria, with intrinsic roles in de novo PE synthesis by the Kennedy pathway and intracellular redistribution of ethanolamine.

The Mechanism of Traditional Chinese Medicine for the Treatment of Obesity

Obesity is the lipid deposition caused by the imbalance between energy intake and consumption caused by a variety of factors. Obesity can lead to multiple systemic complications. At present, the treatment of obesity is mainly lifestyle intervention, drug weight loss, and weight loss surgery, but the curative effect is limited or the side effects are serious. Traditional Chinese medicine plays a unique role in the treatment of obesity. Existing studies have found that traditional Chinese medicine can treat obesity in a variety of ways, such as regulating intestinal microflora, enhancing hormone level, regulating fat metabolism, and so on. In this review, we will introduce and summarize the mechanism of traditional Chinese medicine in the treatment of obesity.

Protein kinase C promotes choline transporter‑like protein 1 function via improved cell surface expression in immortalized human hepatic cells

Choline is used to synthesize phospholipids and a lack of choline induces a number of liver-related diseases, including non-alcoholic steatohepatitis. The current study characterized the choline uptake system, at molecular and functional levels, in the immortalized human hepatic cell line, Fa2N-4, to identify the specific choline transporter involved in choline uptake. The present study also assesed whether choline deficiency or the inhibited choline uptake affected cell viability and apoptosis. Reverse transcription-quantitative polymerase chain reaction (PCR) revealed choline transporter-like protein 1 (CTL1) and CTL2 mRNA and protein expression in Fa2N-4 cells. [Methyl-³H]choline studies revealed choline uptake was saturable and mediated by a single transport system that functioned in a Na⁺-independent but pH-dependent manner, which was similar to CTL1. Hemicholinium-3 (HC-3), which is a choline uptake inhibitor, and choline deficiency inhibited cell viability, increased caspase-3 and −7 activities, and increased fluorescein isothiocyanate-Annexin V immunofluorescent staining indicated apoptosis. Immunofluorescent staining also revealed CTL1 and CTL2 localized in plasma and mitochondrial membranes, respectively. [Methyl-³H]choline uptake was enhanced by a protein kinase C (PKC) activator, phorbol-12-myristate 13-acetate (PMA). Immunofluorescence staining and western blot analysis demonstrated increased CTL1 expression on the cell membrane following PMA treatment. The results of current study indicated that extracellular choline is primarily transported via CTL1, relying on a direct H⁺ gradient that functions as a driving force in Fa2N-4 cells. Furthermore, it was hypothesized that CTL1 and the choline uptake system are strongly associated with cell survival, and that the choline uptake system is modulated by PKC signaling via increased CTL1 expression on the cell surface. These findings provide further insights into the pathogenesis of liver disease involving choline metabolism.

Hepatic Expression of PEMT, but Not Dietary Choline Supplementation, Reverses the Protection against Atherosclerosis in Pemt-/-/Ldlr-/- Mice

Background

Phosphatidylethanolamine N-methyltransferase (PEMT) converts phosphatidylethanolamine to phosphatidylcholine. Pemt-/-/low density lipoprotein receptor (Ldlr)-/- mice have significantly reduced plasma lipids and are protected against atherosclerosis. Recent studies have shown that choline can be metabolized by the gut flora into trimethylamine-N-oxide (TMAO), which is an emerging risk factor for atherosclerosis.

Objective

The objective of this study was to determine whether ectopic hepatic PEMT expression or choline supplementation would promote atherosclerosis in Pemt-/-/Ldlr-/- mice.

Methods

Male 8- to 10-wk-old Pemt+/+/Ldlr-/- (SKO) and Pemt-/-/Ldlr-/- (DKO) mice were injected with an adeno-associated virus (AAV) expressing green fluorescent protein (GFP) or human PEMT and fed a Western diet (40% of calories from fat, 0.5% cholesterol) for 8 wk. In a separate experiment, 8- to 10-wk-old SKO and half of the DKO male mice were fed a Western diet with normal (3 g/kg) choline for 12 wk. The remaining DKO mice [choline-supplemented (CS) DKO] were fed a CS Western diet (10 g choline/kg). Plasma lipid concentrations, choline metabolites, and aortic atherosclerosis were measured.

Results

Plasma cholesterol, plasma TMAO, and aortic atherosclerosis were reduced by 60%, 40%, and 80%, respectively, in DKO mice compared with SKO mice. AAV-PEMT administration increased plasma cholesterol and TMAO by 30% and 40%, respectively, in DKO mice compared with AAV-GFP-treated DKO mice. Furthermore, AAV-PEMT-injected DKO mice developed atherosclerotic lesions similar to SKO mice. In the second study, there was no difference in atherosclerosis or plasma cholesterol between DKO and CS-DKO mice. However, plasma TMAO concentrations were increased 2.5-fold in CS-DKO mice compared with DKO mice.

Conclusions

Reintroducing hepatic PEMT reversed the atheroprotective phenotype of DKO mice. Choline supplementation did not increase atherosclerosis or plasma cholesterol in DKO mice. Our data suggest that plasma TMAO does not induce atherosclerosis when plasma cholesterol is low. Furthermore, this is the first report to our knowledge that suggests that de novo choline synthesis alters TMAO status.

Betaine and Choline Improve Lipid Homeostasis in Obesity by Participation in Mitochondrial Oxidative Demethylation

We investigated the metabolic effects of betaine (Bet) supplementation on CTP:phosphoethanolamine cytidylyltransferase/Pcyt2 heterozygous mice (HET). HET received either no treatment or were allowed access to 1% Bet supplemented water for 8 weeks. As we previously showed with choline (Cho), Bet improved hypertriglyceridemia, and hepatic steatosis in HET. The protection from obesity associated with reduced hepatic steatosis and increased lipid breakdown in adipocytes was attributed to increased energy requirements for metabolism and elimination of supplemented Bet and Cho. ¹H-NMR-based profiling revealed metabolic changes caused by Bet and Cho supplementation. Cho increased the citric acid cycle intermediate succinic acid while reducing isoleucine, valine, threonine, and lysine. Bet increased α-ketoglutaric acid and did not stimulate catabolism of amino acids. Increased histidine and alanine are specific biomarkers for Bet treatment. Cho and Bet caused glycerol accumulation and reduced sarcosine, taurine, acetate, and β-hydroxybutyrate levels. These data provide new insights on how Cho and Bet supplementation can aid in treatment of obesity related disorders due to their positive effects on lipolysis, the citric acid cycle, and mitochondrial oxidative demethylation.

Choline supplementation alleviates fluoride-induced testicular toxicity by restoring the NGF and MEK expression in mice

Fluoride is known to cause male reproductive toxicity, and the elucidation of its underlying mechanisms is an ongoing research focus in reproductive toxicology and epidemiology. Choline, an essential nutrient, has been extensively studied for its benefits in nervous system yet was rarely discussed for its prospective effect in male reproductive system. This study aims to explore the potential protective role of choline against NaF-induced male reproductive toxicity via MAPK pathway. The male mice were administrated by 150mg/L NaF in drinking water, 5.75g/kg choline in diet, and their combination respectively from maternal gestation to postnatal 15weeks. The results showed that fluoride exposure reduced body weight growth, lowered sperm count and survival percentages, altered testicular histology, down-regulated the mRNA expressions of NGF, Ras, Raf, and MEK genes in testes, as well as significantly decreased the expressions of both NGF and phosphor-MEK proteins in testes. Examination of data from choline-treated mice revealed that choline supplementation ameliorated these fluoride-induced changes. Taken together, our findings suggest that choline supplementation alleviates fluoride-induced testicular toxicity by restoring the NGF and phosphor-MEK expression. The suitable dosage and supplementation periods of choline await further exploration.

Adaptations to excess choline in insulin resistant and Pcyt2 deficient skeletal muscle

It was hypothesized that choline supplementation in insulin resistant (IR) CTP:phosphoethanolamine cytidylyltransferase deficient (Pcyt2^+/-) mice would ameliorate muscle function by remodeling glucose and fatty acid (FA) metabolism. Pcyt2^+/- mice either received no treatment or were allowed access to 2 mg/mL choline in drinking water for 4 weeks. Skeletal muscle was harvested from choline treated and untreated mice. Lipid analysis and metabolic gene expression and signaling pathways were compared between untreated Pcyt2^+/- mice, treated Pcyt2^+/- mice, and Pcyt2^+/+ mice. The major positive effect of choline supplementation on IR muscle was the reduction of glucose utilization for FA and triglyceride (TAG) synthesis and increased muscle glucose storage as glycogen. Choline reduced the expression of genes for FA and TAG formation (Scd1, Fas, Srebp1c, Dgat1/2), upregulated the genes for FA oxidation (Cpt1, Pparα, Pgc1α), and had minor effects on phospholipid and lipolysis genes. Pcyt2^+/- muscle had reduced insulin signaling (IRS1), autophagy (LC3), and choline transport (CTL1) proteins that were restored by choline treatment. Additionally, choline activated AMPK and Akt while inhibiting mTORC1 phosphorylation. These data established that choline supplementation could restore muscle glucose metabolism by reducing lipogenesis and improving mitochondrial and intracellular signaling for protein and energy metabolism in insulin resistant Pcyt2 deficient mice.

Acceptability, Safety, and Efficacy of Oral Administration of Extracts of Black or Red Maca (Lepidium meyenii) in Adult Human Subjects: A Randomized, Double-Blind, Placebo-Controlled Study

The plant maca, grown at 4000 m altitude in the Peruvian Central Andes, contains hypocotyls that have been used as food and in traditional medicine for centuries. The aim of this research was to provide results on some health effects of oral administration of spray-dried extracts of black or red maca (Lepidium meyenii) in adult human subjects living at low (LA) and high altitude (HA). A total of 175 participants were given 3 g of either placebo, black, or red maca extract daily for 12 weeks. Primary outcomes were changes in sexual desire, mood, energy, health-related quality of life score (HRQL), and chronic mountain sickness (CMS) score, or in glycaemia, blood pressure, and hemoglobin levels. Secondary outcomes were acceptability and safety, assessed using the Likert test and side effect self-recording, respectively, and the effect of altitude. At low altitude, 32, 30, and 32 participants started the study receiving placebo, red maca, or black maca, respectively. At high altitudes, 33, 35, and 31 participants started the study receiving placebo, red maca, and black maca, respectively. Consumption of spray-dried extracts of red and black maca resulted in improvement in mood, energy, and health status, and reduced CMS score. Fatty acids and macamides were higher in spray-dried extracts of black maca than in red maca. GABA predominated in spray-dried extracts of red maca. Effects on mood, energy, and CMS score were better with red maca. Black maca and, in smaller proportions, red maca reduced hemoglobin levels only in highlanders with abnormally high hemoglobin levels; neither variety of maca reduced hemoglobin levels in lowlanders. Black maca reduced blood glucose levels. Both varieties produced similar responses in mood, and HRQL score. Maca extracts consumed at LA or HA had good acceptability and did not show serious adverse effects. In conclusion, maca extract consumption relative to the placebo improved quality of life parameters. Differences in the level of improvement between red and black maca are probably due to differences in the composition of these two plant varieties. Both maca extracts were well tolerated and safe.

Hepatitis B virus X protein (HBx)-induced abnormalities of nucleic acid metabolism revealed by (1)H-NMR-based metabonomics

Hepatitis B virus X protein (HBx) plays an important role in HBV-related hepatocarcinogenesis; however, mechanisms underlying HBx-mediated carcinogenesis remain unclear. In this study, an NMR-based metabolomics approach was applied to systematically investigate the effects of HBx on cell metabolism. EdU incorporation assay was conducted to examine the effects of HBx on DNA synthesis, an important feature of nucleic acid metabolism. The results revealed that HBx disrupted metabolism of glucose, lipids, and amino acids, especially nucleic acids. To understand the potential mechanism of HBx-induced abnormalities of nucleic acid metabolism, gene expression profiles of HepG2 cells expressing HBx were investigated. The results showed that 29 genes involved in DNA damage and DNA repair were differentially expressed in HBx-expressing HepG2 cells. HBx-induced DNA damage was further demonstrated by karyotyping, comet assay, Western blotting, immunofluorescence and immunohistochemistry analyses. Many studies have previously reported that DNA damage can induce abnormalities of nucleic acid metabolism. Thus, our results implied that HBx initially induces DNA damage, and then disrupts nucleic acid metabolism, which in turn blocks DNA repair and induces the occurrence of hepatocellular carcinoma (HCC). These findings further contribute to our understanding of the occurrence of HCC.