AMP-kinase alpha2 subunit gene PRKAA2 variants are associated with total cholesterol, low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol in normal women

Genomic adaptation to extreme climate conditions in beef cattle as a consequence of cross-breeding program

BACKGROUND

Understanding the evolutionary forces related to climate changes that have been shaped genetic variation within species has long been a fundamental pursuit in biology. In this study, we generated whole-genome sequence (WGS) data from 65 cross-bred and 45 Mongolian cattle. Together with 62 whole-genome sequences from world-wide cattle populations, we estimated the genetic diversity and population genetic structure of cattle populations. In addition, we performed comparative population genomics analyses to explore the genetic basis underlying variation in the adaptation to cold climate and immune response in cross-bred cattle located in the cold region of China. To elucidate genomic signatures that underlie adaptation to cold climate, we performed three statistical measurements, fixation index (FST), log₂ nucleotide diversity (θπ ratio) and cross population composite likelihood ratio (XP-CLR), and further investigated the results to identify genomic regions under selection for cold adaptation and immune response-related traits.

RESULTS

By generating WGS data, we investigated the population genetic structure and phylogenetic relationship of studied cattle populations. The results revealed clustering of cattle groups in agreement with their geographic distribution. We detected noticeable genetic diversity between indigenous cattle ecotypes and commercial populations. Analysis of population structure demonstrated evidence of shared genetic ancestry between studied cross-bred population and both Red-Angus and Mongolian breeds. Among all studied cattle populations, the highest and lowest levels of linkage disequilibrium (LD) per Kb were detected in Holstein and Rashoki populations (ranged from ~ 0.54 to 0.73, respectively). Our search for potential genomic regions under selection in cross-bred cattle revealed several candidate genes related with immune response and cold shock protein on multiple chromosomes. We identified some adaptive introgression genes with greater than expected contributions from Mongolian ancestry into Molgolian x Red Angus composites such as TRPM8, NMUR1, PRKAA2, SMTNL2 and OXR1 that are involved in energy metabolism and metabolic homeostasis. In addition, we detected some candidate genes probably associated with immune response-related traits.

CONCLUSION

The study identified candidate genes involved in responses to cold adaptation and immune response in cross-bred cattle, including new genes or gene pathways putatively involved in these adaptations. The identification of these genes may clarify the molecular basis underlying adaptation to extreme environmental climate and as such they might be used in cattle breeding programs to select more efficient breeds for cold climate regions.

Comprehensive analysis of miRNAs, lncRNAs and mRNAs profiles in backfat tissue between Daweizi and Yorkshire pigs

OBJECTIVE

Daweizi (DWZ) is a famous indigenous pig breed in China and characterized by tender meat and high fat percentage. However, the expression profiles and functions of transcripts in DWZ pigs is still in infancy. The object of this study was to depict the transcript profiles in DWZ pigs and screen the potential pathway influence adipogenesis and fat deposition.

METHODS

Histological analysis of backfat tissue was firstly performed between DWZ and lean-type Yorkshire pigs, and then RNA sequencing technology was utilized to explore miRNAs, lncRNAs and mRNAs profiles in backfat tissue. 18 differentially expressed (DE) transcripts were randomly selected for quantitative real-time polymerase chain reaction (QPCR) to validate the reliability of the sequencing results. Finally, gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis were conducted to investigate the potential pathways influence adipocyte differentiation, adipogenesis and lipid metabolism, and a schematic model was further proposed.

RESULTS

A total of 1,625 differentially expressed transcripts were identified in DWZ pigs, including 27 upregulated and 45 downregulated miRNAs, 64 upregulated and 119 downregulated lncRNA, 814 upregulated and 556 downregulated mRNAs. QPCR analysis exhibited strong consistency with the sequencing data. GO and KEGG analysis elucidated that the differentially expressed transcripts were mainly associated with cell growth and death, signal transduction, peroxisome proliferator-activated receptors (PPAR), AMP-activated protein kinase (AMPK), PI3K-Akt, adipocytokine and foxo signaling pathways, all of which are strongly involved in cell development, lipid metabolism and adipogenesis. Further analysis indicated that the BGIR9823_87926/miR-194a-5p/AQP7 network may be effective in the process of adipocyte differentiation or adipogenesis.

CONCLUSION

Our study provides comprehensive insights into the regulatory network of backfat deposition and lipid metabolism in pigs from the point of view of miRNAs, lncRNAs and mRNAs.

Embryo developmental toxicity in marine medaka (Oryzias melastigma) due to parental and embryonic 17α-ethinylestradiol exposure

The synthetic estrogen 17α-ethinylestradiol (EE2) is a common component of hormone therapy and oral contraceptives and has been widely used for nearly 60 years. Numerous studies have shown that exposure to EE2 can affect embryonic development in a number of fish species. The effects of parental and embryonic EE2 exposure on embryo developmental toxicity and the underlying molecular mechanisms, however, have rarely been examined. In this study, embryos collected from parental EE2-exposed adult fish were examined to assess EE2-induecd toxicity during embryo development. The rate of embryo development including heart rate, hatching rate, and larval locomotion were measured to assess embryo developmental toxicity. The embryonic transcriptome was used to delineate the related developmental toxicity pathways. Our results suggest that parental and embryonic EE2 exposure resulted in growth retardation including a reduction in embryo heart rate, a delay in the appearance eye pigmentation, decreased hatching rate and impaired larval locomotion. In addition, gene ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and Ingenuity Pathway Analysis (IPA) of transcriptome revealed that these impairments are controlled by estrogen receptor and related to eye structure, neuronal and synaptic structure, and behaviour. The key factors identified, including PRKAA2, APOB, EPHB2, OXTR, NR2E3, and POU4F2, could serve as biomarkers for assessing EE2-induced embryo developmental toxicity. For the first time, our results show that eye pigmentation is a potentially sensitive marker of EE2-induced embryo developmental toxicity.

Single Nucleotide Polymorphism in the 3' Untranslated Region of PRKAA2 on Cardiometabolic Parameters in Type 2 Diabetes Mellitus Patients Who Received Metformin

Purpose

This study aimed to explore the association of rs857148 A>C as 3'UTR variants with blood pressure, HbA1c profile, and lipid profiles as cardiometabolic parameters among patients with T2DM receiving metformin.

Patients and Methods

This cross-sectional analytic research was conducted with 114 consecutively selected patients with T2DM. Polymerase chain reaction-restriction fragment length polymorphism was conducted to determine rs857148. A total of 108 patients fulfilled inclusion and exclusion criteria.

Results

Genotype distribution agreed with the Hardy Weinberg Equation for Equilibrium (p>0.05) but wildtype allele was found as the minor allele. Subjects with CC genotype and C allele had enhanced HbA1c levels (OR=7.12; 95% CI=1.05-48.26; p=0.04; OR=1.66; 95% CI=1.06-2.60; p=0.03, respectively). It was confirmed by dominant model whereas subjects with AA tended to have reduced HbA1c compared to AC+CC genotype (OR=0.15; 95% CI=0.02-0.97; p=0.047). AC genotype had significant correlation to total cholesterol (OR=1.05; 95% CI=1.01-1.10; p=0.03) compared to AA genotype.

Conclusion

We conclude that polymorphism of rs87148, specifically CC genotype and C allele, has a significant association with HbA1c and total cholesterol after considering oral hypoglycemia agent dose, age, gender, and combination therapy, compared to AA genotype. Future studies that involve a larger sample population and more rigorous selection criteria are required.

Association between Three Variants in the PRKAA2 gene, rs2796498, rs9803799, and rs2746342, with 10-year ASCVD Risk on Newly Diagnosed T2DM in Yogyakarta, Indonesia

BACKGROUND: AMPK has pivotal roles in glucose and lipid metabolism, including  AMPKa2, which PRKAA2 encodes. Metformin as an anti-hyperglycemia agent acts through AMPK. Poor glycemia control among patients with type 2 diabetes mellitus (T2DM) could increase atherosclerosis cardiovascular disease (ASCVD) risk. Therefore, PRKAA2 genetic variation might contribute to 10-year ASCVD risk in patients with newly diagnosed T2DM receiving monotherapy metformin. AIM: The study aimed to detect an association between PRKAA2 genetic variation with 10 year-ASCVD risk among newly diagnosed T2DM patients prescribed monotherapy metformin. METHODS: This present study was a case-control study involving 107 participants. Analysis of PRKAA2 genetic variation was performed using the TaqMan assay. RESULTS: A total of 91 participants who fulfilled our criteria enrolled in this study. Most of the participants were female, with mean age 54.40±7.75 years old, mean HbA1c level of 8.35±1.31%, and the lipid profile indicated normal conditions. There was a significant difference in age (p<0.01), HbA1c level (p=0.04), sex (p<0.01), and smoking status (p<0.01) between low-risk and high-risk groups. The GT genotype of rs9803799 had 187.86 times higher possibility for high-risk of 10-year ASCVD risk than TT genotype (OR=187.86, 95%CI:2.98–11863.51). The dominant model of rs9803799 showed that GT+GG had 94.33 times higher possibility for high-risk of 10-year ASCVD risk than TT genotype (OR=94.33; 95%CI:2.32–3841.21). Other results showed that G allele of rs980377 had 20.48 times higher possibility for high-risk of 10-year ASCVD risk than T allele (OR = 20.48; 95%CI:1.48–283.30). These associations were found after multivariate analysis. CONCLUSION: Our findings indicated that rs9803799 as one of PRKAA2 genetic variations might impact the 10-year ASCVD risk among newly diagnosed T2DM patients receiving monotherapy metformin. After considering non-genetic factors, patient assessment should include potential genetic factors in cases with hyperglycemia involving treatment affecting glucose and lipid metabolism such as monotherapy metformin.   Keywords: PRKAA2, genetic variation, atherosclerosis cardiovascular disease, type 2 diabetes mellitus, metformin, Indonesia

Identification of Differentially Expressed Genes and Lipid Metabolism Signaling Pathways between Muscle and Fat Tissues in Broiler Chickens

In this study, signaling pathways and key differentially expressed genes (DEGs) involved in lipid metabolism in muscle and fat tissues were investigated. Muscle and abdominal fat tissues were obtained from 35-day-old female broilers for RNA sequencing. DEGs between muscle and fat tissues were identified. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses of DEGs were performed. A total of 6130 DEGs were identified to be significantly enriched in 365 GO terms, most of which were involved in biological processes, cellular components, and molecular functions in muscle and fat tissues. Three important lipid signaling pathways (pyruvate metabolism, the insulin signaling pathway, and the adipocytokine signaling pathway) were identified among the fat and muscle tissues of broilers. The key common DEGs in these pathways included phosphoenolpyruvate carboxykinase 2 (PCK2), acetyl-CoA carboxylase 1 alpha and beta (ACACA and ACACB), and the mitogen-activated protein kinase (AMPK) gene family. Hence, our findings revealed the pathways and key genes and gene families involved in the regulation of fat deposition in the muscle and fat tissues of broilers.

AMPK Subunits Harbor Largely Nonoverlapping Genetic Determinants for Body Fat Mass, Glucose Metabolism, and Cholesterol Metabolism

CONTEXT

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a heterotrimeric enzyme and central regulator of cellular energy metabolism. The impact of single nucleotide polymorphisms (SNPs) in all 7 AMPK subunit genes on adiposity, glucose metabolism, and lipid metabolism has not yet been systematically studied.

OBJECTIVE

To analyze the associations of common SNPs in all AMPK genes, and of different scores thereof, with adiposity, insulin sensitivity, insulin secretion, blood glucose, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, total cholesterol, and triglycerides.

STUDY DESIGN AND METHODS

A cohort of 2789 nondiabetic participants from the Tübingen Family study of type 2 diabetes, metabolically characterized by oral glucose tolerance test and genotyped by genome-wide SNP array, was analyzed.

RESULTS

We identified 6 largely nonoverlapping SNP sets across 4 AMPK genes (PRKAA1, PRKAA2, PRKAG2, PRKAG3) associated with adiposity, insulin sensitivity, insulin secretion, blood glucose, total/LDL cholesterol, or HDL cholesterol, respectively. A genetic score of body-fat-increasing alleles revealed per-allele effect sizes on body mass index (BMI) of +0.22 kg/m2 (P = 2.3 × 10-7), insulin sensitivity of -0.12 × 1019 L2/mol2 (P = 9.9 × 10-6) and 2-hour blood glucose of +0.02 mmol/L (P = 0.0048). Similar effects on blood glucose were observed with scores of insulin-sensitivity-reducing, insulin-secretion-reducing and glucose-raising alleles, respectively. A genetic cholesterol score increased total and LDL cholesterol by 1.17 mg/dL per allele (P = 0.0002 and P = 3.2 × 10-5, respectively), and a genetic HDL score decreased HDL cholesterol by 0.32 mg/dL per allele (P = 9.1 × 10-6).

CONCLUSIONS

We describe largely nonoverlapping genetic determinants in AMPK genes for diabetes-/atherosclerosis-related traits, which reflect the metabolic pathways controlled by the enzyme. Formation of trait-specific genetic scores revealed additivity of allele effects, with body-fat-raising alleles reaching a marked effect size. (J Clin Endocrinol Metab XX: 0-0, 2019).

Investigation of the effect of telomerase inhibitor BIBR1532 on breast cancer and breast cancer stem cells

It is emphasized that cancer stem cells (CSCs) forming the subpopulation of tumour cells are responsible for tumour growth, metastasis, and cancer drug resistance. Inadequate response to conventional therapy in breast cancer leads researchers to find new treatment methods and literature surveys that support CSC studies. A selective anticancer agent BIBR1532 inhibits the telomerase enzyme. Many of the chemotherapeutic drugs used in clinical trials have harmful effects, but the advantage of telomerase-based inhibitors is that they are less toxic to healthy tissues. The phosphoinositide 3-kinase (PI3K)/serine/threonine kinase (Akt)/mammalian target of rapamycin (mTOR) pathway is common in breast cancer, and the interaction between the mTOR pathway and human telomerase reverse transcriptase (hTERT) is essential for the survival of cancer cells. In our study, we treated MCF-7, breast cancer stem cell (BCSC) and normal breast epithelial cell MCF10A with the BIBR1532 inhibitor. The IC ₅₀ doses for the 48th hour of BIBR1532 treatment were detected as 34.59 μM in MCF-7, 29.91 μM in BCSCs, and 29.07 μM in MCF10A. It has been observed that this agent induces apoptosis in the BCSC and MCF-7 cell lines. According to the results of cell cycle analysis, G ₂ /M phase accumulation was observed in BCSC and MCF-7 cell lines. It has also been shown that BIBR1532 suppresses telomerase activity in BCSC and MCF-7. The effect of BIBR1532 on the mTOR signalling pathway has been investigated for the first time in this study. It is thought that the telomerase inhibitor may bring a new approach to the treatment and it may be useful in the treatment of CSCs.

Molecular Pathogenesis of Familial Wolff-Parkinson-White Syndrome

Familial Wolff-Parkinson-White (WPW) syndrome is an autosomal dominant inherited disease and consists of a small percentage of WPW syndrome which exhibits ventricular pre-excitation by development of accessory atrioventricular pathway. A series of mutations in PRKAG2 gene encoding gamma2 subunit of 5'AMP-activated protein kinase (AMPK) has been identified as the cause of familial WPW syndrome. AMPK is one of the most important metabolic regulators of carbohydrates and lipids in many types of tissues including cardiac and skeletal muscles. Patients and animals with the mutation in PRKAG2 gene exhibit aberrant atrioventricular conduction associated with cardiac glycogen overload. Recent studies have revealed "novel" significance of canonical pathways leading to glycogen synthesis and provided us profound insights into molecular mechanism of the regulation of glycogen metabolism by AMPK. This review focuses on the molecular basis of the pathogenesis of cardiac abnormality due to PRKAG2 mutation and will provide current overviews of the mechanism of glycogen regulation by AMPK. J. Med. Invest. 65:1-8, February, 2018.

Influence of Single-Nucleotide Polymorphisms in PPAR-δ, PPAR-γ, and PRKAA2 on the Changes in Anthropometric Indices and Blood Measurements through Exercise-Centered Lifestyle Intervention in Japanese Middle-Aged Men

The purpose of the current study was to examine the influence of single-nucleotide polymorphisms (SNPs) in the peroxisome proliferator-activated receptor-δ (PPAR-δ), PPAR-γ, and α2 isoforms of the catalytic subunit of AMP-activated protein kinase (PRKAA2) on the extent of changes in anthropometric indices and blood measurements through exercise-centered lifestyle intervention in middle-aged men. A total of 109 Japanese middle-aged male subjects (47.0 ± 0.4 years) participated in the baseline health checkup, 6-month exercise-centered lifestyle intervention, and second checkup conducted several months after the subject completed the intervention. The body mass index (BMI), waist circumference, and clinical measurements, including hemoglobin A_lc (HbA_1c), triglyceride (TG), alanine aminotransferase (ALT), and γ-glutamyl-transpeptidase (γ-GTP), were measured at the baseline and second checkup. The three SNPs of PPAR-δ A/G (rs2267668), PPAR-γ C/G (rs1801282), and PRKAA2 A/G (rs1418442) were determined. Blunted responses in the reduction in the BMI and waist circumference were observed in A/A carriers of PPAR-δ SNP compared with G allele carriers (all p < 0.05). The A/A carriers also displayed less-marked improvements in HbA_1c, TG, ALT, and γ-GTP (all p < 0.05). The current results suggest that A/A carriers of PPAR-δ SNP (rs2267668) may enjoy fewer beneficial effects of exercise-centered lifestyle intervention on anthropometric indices and blood measurements.

Effect of AMP-activated protein kinase subunit alpha 2 (PRKAA2) genetic polymorphisms on susceptibility to type 2 diabetes mellitus and diabetic nephropathy in a Chinese population

BACKGROUND

It is well known that AMP-activated protein kinase (AMPK) is a key factor affecting the development of type 2 diabetes mellitus (T2DM). The single nucleotide polymorphism (SNP) rs2746342 in the AMPK alpha 2 subunit gene (PRKAA2) has been found to be associated with susceptibility to T2DM in the Chinese Han population. The present study further investigates the association of PRKAA2 genotypes with susceptibility to T2DM and its complication, diabetic nephropathy.

METHODS

The PRKAA2 genotypes of 406 T2DM patients and 214 controls from the Chinese Han population were determined with regard to SNPs rs10789038, rs2796498 and rs2746342. The association between these SNPs and susceptibility to T2DM and diabetic nephropathy was evaluated. The clinical characteristics differed significantly between T2DM patients and controls.

RESULTS

After adjustment for age, sex and body mass index, there was an obvious relationship between T2DM and both rs10789038 (odds ratio [OR] 1.634; P = 0.015) and rs2796498 (OR 0.656; P = 0.030), but not rs2746342. There was haplotype association of PRKAA2 rs10789038-rs2796498-rs2746342 with T2DM susceptibility. In addition, rs2796498 was found to be related to the susceptibility to diabetic nephropathy.

CONCLUSIONS

Polymorphisms in rs10789038 and rs2796498 are associated with the susceptibility to T2DM, and rs2796498 may be related to diabetic nephropathy.

Genetic dissection in a mouse model reveals interactions between carotenoids and lipid metabolism

Carotenoids affect a rich variety of physiological functions in nature and are beneficial for human health. However, knowledge about their biological action and the consequences of their dietary accumulation in mammals is limited. Progress in this research field is limited by the expeditious metabolism of carotenoids in rodents and the confounding production of apocarotenoid signaling molecules. Herein, we established a mouse model lacking the enzymes responsible for carotenoid catabolism and apocarotenoid production, fed on either a β-carotene- or a zeaxanthin-enriched diet. Applying a genome wide microarray analysis, we assessed the effects of the parent carotenoids on the liver transcriptome. Our analysis documented changes in pathways for liver lipid metabolism and mitochondrial respiration. We biochemically defined these effects, and observed that β-carotene accumulation resulted in an elevation of liver triglycerides and liver cholesterol, while zeaxanthin accumulation increased serum cholesterol levels. We further show that carotenoids were predominantly transported within HDL particles in the serum of mice. Finally, we provide evidence that carotenoid accumulation influenced whole-body respiration and energy expenditure. Thus, we observed that accumulation of parent carotenoids interacts with lipid metabolism and that structurally related carotenoids display distinct biological functions in mammals.

PADPIN: protein-protein interaction networks of angiogenesis, arteriogenesis, and inflammation in peripheral arterial disease

Peripheral arterial disease (PAD) results from an obstruction of blood flow in the arteries other than the heart, most commonly the arteries that supply the legs. The complexity of the known signaling pathways involved in PAD, including various growth factor pathways and their cross talks, suggests that analyses of high-throughput experimental data could lead to a new level of understanding of the disease as well as novel and heretofore unanticipated potential targets. Such bioinformatic analyses have not been systematically performed for PAD. We constructed global protein-protein interaction networks of angiogenesis (Angiome), immune response (Immunome), and arteriogenesis (Arteriome) using our previously developed algorithm GeneHits. The term "PADPIN" refers to the angiome, immunome, and arteriome in PAD. Here we analyze four microarray gene expression datasets from ischemic and nonischemic gastrocnemius muscles at day 3 posthindlimb ischemia (HLI) in two genetically different C57BL/6 and BALB/c mouse strains that display differential susceptibility to HLI to identify potential targets and signaling pathways in angiogenesis, immune, and arteriogenesis networks. We hypothesize that identification of the differentially expressed genes in ischemic and nonischemic muscles between the strains that recovers better (C57BL/6) vs. the strain that recovers more poorly (BALB/c) will help for the prediction of target genes in PAD. Our bioinformatics analysis identified several genes that are differentially expressed between the two mouse strains with known functions in PAD including TLR4, THBS1, and PRKAA2 and several genes with unknown functions in PAD including EphA4, TSPAN7, SLC22A4, and EIF2a.

Chlorogenic acid-enriched extract from Eucommia ulmoides leaves inhibits hepatic lipid accumulation through regulation of cholesterol metabolism in HepG2 cells

CONTEXT

Eucommia ulmoides Oliver (Eucommiaceae) leaf exhibits beneficial lipid-lowering and anti-obesity effects. However, the mechanisms remain unknown.

OBJECTIVE

The objective of this study is to investigate the lipid-lowering effects of chlorogenic acid (CGA)-enriched extract from this plant (CAEF) in human hepatoma HepG2 cells, focusing on cholesterol metabolism.

MATERIALS AND METHODS

HepG2 cells were treated with CAEF (10, 20, 25, 40, 60, and 80 mg/L), CGA (0.3, 3, 30, 300, and 600 μmol/L), and simvastatin (0.1, 1, 10, 50, and 100 μmol/L) for 24 or 48 h. The cytotoxicity, Oil red O staining, total cholesterol, and triacylglycerol in supernatants were determined. The mRNA expression of genes involved in cholesterol metabolism was determined with RT-PCR. The protein expression of HMG-CoA reductase (HMGCR) was examined by immunocytochemistry and western-blot.

RESULTS

The IC50 values were 59.2 mg/L for CAEF, 335.9 μmol/L for CGA, and 10.5 μmol/L for simvastatin. By treating cells with CAEF (25 mg/L), CGA (30 μmol/L), or simvastatin (10 μmol/L) for 48 h, the efflux of total cholesterol and triacylglycerol was increased (CAEF, 4.06- and 31.00-folds; CGA, 2.94- and 2.17-folds; and simvastatin, 3.94- and 24.67-folds), and the cellular lipid droplets were reduced in Oil red O staining. CAEF and CGA increased mRNA expression of ABCA1, CYP7A1, and AMPKα2, while CAEF and simvastatin decreased SREBP2. However, their effects on LXRα mRNA expression were variable. Importantly, all drugs significantly inhibited protein expression of HMGCR at mRNA and protein levels.

DISCUSSION AND CONCLUSION

CAEF is a promising dietary supplement to prevent obesity and dyslipidemia and the effects appear to be due, at least in part, to regulating cholesterol metabolism through inhibition of HMGCR in HepG2 cells.

Genomics and genetics in the biology of adaptation to exercise

This article is devoted to the role of genetic variation and gene-exercise interactions in the biology of adaptation to exercise. There is evidence from genetic epidemiology research that DNA sequence differences contribute to human variation in physical activity level, cardiorespiratory fitness in the untrained state, cardiovascular and metabolic response to acute exercise, and responsiveness to regular exercise. Methodological and technological advances have made it possible to undertake the molecular dissection of the genetic component of complex, multifactorial traits, such as those of interest to exercise biology, in terms of tissue expression profile, genes, and allelic variants. The evidence from animal models and human studies is considered. Data on candidate genes, genome-wide linkage results, genome-wide association findings, expression arrays, and combinations of these approaches are reviewed. Combining transcriptomic and genomic technologies has been shown to be more powerful as evidenced by the development of a recent molecular predictor of the ability to increase VO2max with exercise training. For exercise as a behavior and physiological fitness as a state to be major players in public health policies will require that the role of human individuality and the influence of DNA sequence differences be understood. Likewise, progress in the use of exercise in therapeutic medicine will depend to a large extent on our ability to identify the favorable responders for given physiological properties to a given exercise regimen.

A healthier approach to clinical trials evaluating resveratrol for primary prevention of age‐related diseases in healthy populations

In recent years, the wealth of basic science research supporting resveratrol's potential to treat, delay, and even prevent age-related chronic diseases has led to a number of human clinical trials. While such translational research has yielded promising results in clinical populations, recently published conflicting results from studies evaluating resveratrol's potential for primary prevention of chronic disease in healthy / asymptomatic individuals have generated considerable controversy and do not initially appear consistent with findings from animal models. We argue that trials targeting healthy humans are often fundamentally flawed owing to inappropriate use of paradigms only applicable to populations with overt clinical disease and the consequent misleading (typically negative) results can severely retard advancement of drug development. To appropriately perform translational research centered on resveratrol as a primary prevention agent in non-clinical populations, it is critical to utilize study designs which can provide adequate information on clinically relevant outcome measures, avoid paradigms and assumptions from interventions which are specific to clinical populations, and maintain realistic expectations compared to interventions which provide the theoretical maximal response (e.g., caloric restriction and aerobic exercise training).

Regulators of blood lipids and lipoproteins? PPARδ and AMPK, induced by exercise, are correlated with lipids and lipoproteins in overweight/obese men and women

PPARδ is a transcription factor regulating the expression of genes involved in oxidative metabolism, which may regulate blood cholesterols through transcription of oxidative and lipoprotein metabolism genes. To determine the association of skeletal muscle PPARδ content with blood lipids and lipoproteins before and following exercise, overweight and obese men (n = 9) and women (n = 7) were recruited; age, BMI, body fat percentage, and Vo(2max) were (means ± SE) 45 ± 2.5 yr, 31.9 ± 1.4 kg/m(-2), 41.1 ± 1.5%, and 26.0 ± 1.3 mLO(2)·kg(-1)·min(-1), respectively. Subjects performed 12 wk of endurance exercise training (3 sessions/wk, progressing to 500 kcal/session). To assess the acute exercise response, subjects performed a single exercise session on a treadmill (70% Vo(2max), 400 kcal energy expenditure) before and after training. Muscle and blood samples were obtained prior to any exercise and 24 h after each acute exercise session. Muscle was analyzed for protein content of PPARδ, PPARα, PGC-1α, AMPKα, and the oxidative and lipoprotein markers FAT/CD36, CPT I, COX-IV, LPL, F(1) ATPase, ABCAI, and LDL receptor. Blood was assessed for lipids and lipoproteins. Repeated-measures ANOVA revealed no influence of sex on measured outcomes. PPARδ, PGC-1α, FAT/CD36, and LPL content were enhanced following acute exercise, whereas PPARα, AMPKα, CPT I, and COX-IV content were enhanced only after exercise training. PPARδ content negatively correlated with total and LDL cholesterol concentrations primarily in the untrained condition (r ≤ -0.4946, P < 0.05), whereas AMPKα was positively correlated with HDL cholesterol concentrations regardless of exercise (r ≥ 0.5543, P < 0.05). Our findings demonstrate exercise-induced expression of skeletal muscle PPARs and their target proteins, and this expression is associated with improved blood lipids and lipoproteins in obese adults.

Acute exercise and training alter blood lipid and lipoprotein profiles differently in overweight and obese men and women

Our purpose was to elucidate effects of acute exercise and training on blood lipids-lipoproteins, and high-sensitivity C-reactive protein (hsCRP) in overweight/obese men (n = 10) and women (n = 8); age, BMI, body fat percentage, and VO(2)max were (mean ± SEM): 45 ± 2.5 years, 31.9 ± 1.4 kg·m(-2), 41.1 ± 1.5%, and 25.2 ± 1.3 mlO(2)·kg(-1)·min(-1). Before exercise training subjects performed an acute exercise session on a treadmill (70% VO(2)max, 400 kcal energy expenditure), followed by 12 weeks of endurance exercise training (land-based or aquatic-based treadmill): 3 sessions·week(-1), progressing to 500 kcal·session(-1) during which subjects maintained accustomed dietary habits. After training, the acute exercise session was repeated. Blood samples, obtained immediately before and 24 h after acute exercise sessions, were analyzed for serum lipids, lipoproteins, and hsCRP adjusted for plasma volume shifts. Exercise training increased VO(2)max (+3.67 mlO(2)·kg(-1)·min(-1), P < 0.001) and reduced body weight (-2.7 kg, P < 0.01). Training increased high-density lipoprotein (HDL) and HDL(2b)-cholesterol (HDL-C) concentrations (+3.7 and +2.4 mg·dl(-1), P < 0.05) and particle numbers (+588 and +206 nmol·l(-1), P < 0.05) in men. In women despite no change in total HDL-C, subfractions shifted from HDL(3)-C (-3.2, P < 0.01) to HDL(2b)-C (+3.5, P < 0.05) and HDL(2a)-C (+2.2 mg·dl(-1), P < 0.05), with increased HDL(2b) particle number (+313 nmol·l(-1), P < 0.05). Training reduced LDL(3) concentration and particle number in women (-1.6 mg·dl(-1) and -16 nmol·l(-1), P < 0.05). Acute exercise reduced the total cholesterol (TC): HDL-C ratio in men (-0.16, P < 0.01) and increased hsCRP in all subjects (+0.05 mg·dl(-1), P < 0.05), regardless of training. Training did not affect acute exercise responses. Our data support the efficacy of endurance training, without dietary intervention, to elicit beneficial changes in blood lipids-lipoproteins in obese men and women.

Association study between variants of AMP-activated protein kinase catalytic and regulatory subunit genes with antipsychotic-induced weight gain

Weight gain and metabolic syndrome are the most common deleterious side effects following treatment with second generation antipsychotic drugs such as clozapine and olanzapine. However, the mechanisms underlying these negative effects of second generation antipsychotic drugs are not fully understood. In this study we investigate whether variants in the genes coding for the α-catalytic (PRKAA1, PRAKAA2) and the β regulatory subunits (PRKAB1 and PRKAB2) of the cellular energy sensor AMP-activated protein kinase (AMPK) are associated with antipsychotic-induced weight gain. To accomplish this, ten polymorphisms in 208 schizophrenia or schizoaffective disorder patients treated with clozapine, haloperidol, risperidone or olanzapine for up to 14 weeks were analyzed. Significant association was observed between rs3766522 in PRKAB2 (AA vs. AT + TT; p = 0.022) and rs10789038 in PRKAA2 (GG + GA vs. AA, p = 0.023) with weight change (%) in patients of European ancestry following treatment with clozapine or olanzapine. Allelic association of the T-allele of rs3766522 (p = 0.019) and the G-allele of rs10789038 (p = 0.041) with weight change (%) was also observed. Analysis of raw weight gain revealed that carriers of the T-allele of rs3766522 (AT + TT, 4.3 kg ± 3.7) gained more weight than the AA-genotype carriers (2.5 kg ± 4.5, p = 0.042). Similarly, carriers of the G-allele of rs10789038 (GG + GA, 4.2 kg ± 4.5) gained more weight than AA-homozygotes (1.5 kg ± 2.9, p = 0.014) under antipsychotic treatment. In conclusion, we observed significant associations between polymorphisms in AMPK subunit genes and weight gain induced by clozapine and olanzapine.

AMPK γ2 subunit gene PRKAG2 polymorphism associated with cognitive impairment as well as diabetes in old age

Metabolic and cognitive disorders are closely related. However, the molecular mechanism underlying this association is still elusive. Given the importance of energy metabolism in neuronal cells, AMP-activated protein kinase (AMPK), a master switch of energy metabolism, could be an independent factor affecting cognitive as well as metabolic functions. Therefore, we examined the relationship between the AMPK γ2 gene, the PRKAG2 -26C/T polymorphism and cognitive impairment or diabetes in 1609 subjects aged from 60 to 80. We performed multivariate logistic regression analyses with adjustment for age, gender, education, smoking, alcohol, depression, waist circumference, APOE e4, and stroke history. We found a significant association between the -26C/T polymorphism (CC vs. CT/TT) and cognitive impairment (OR, 1.6; 95% CI, 1.1-2.3). Moreover, this polymorphism (CC/CT vs. TT) was also related to the presence of diabetes (OR, 1.8; 95% CI, 1.2-2.8). Importantly, the relationship with cognitive impairment was still significant in non-diabetic individuals (OR, 1.6; 95% CI, 1.1-2.4). Further analyses with a subpopulation (n=611) revealed that CC homozygotes relative to T-allele carriers had significantly better performances in verbal memory and attentional tasks. These findings collectively support a hypothesis that AMPK has a role not only in metabolic functioning but also in cognitive functioning in humans. Extended longitudinal study with a larger number of samples is warranted.

Lifestyle and socioeconomic-status modify the effects of ADRB2 and NOS3 on adiposity in European-American and African-American adolescents

The aim of the study is to investigate the influence of and interaction between lifestyle behaviors (diet and physical activity (PA)) and single-nucleotide polymorphisms (SNPs) in obesity-candidate genes (ADRB2, APOB and NOS3) on general and central adiposity. Six-hundred-and-twenty-one European-American (EA) and African-American (AA) youths aged 13-19 years were classified by ethnicity (49% AA), gender (45% male), and socioeconomic status (SES). PA and dietary intake with up to seven 24-h recalls were reported for all subjects. Percent body fat (%BF) was measured by dual-energy X-ray absorptiometry, visceral adipose tissue (VAT), and subcutaneous abdominal adipose tissue (SAAT) by magnetic resonance imaging. Reported energy intake (EI) and vigorous PA (VPA) were negative predictors of %BF and SAAT. Carriers of the NOS3 Asp298 allele had higher %BF only in the presence of an adverse environment (low SES). Compared to the most common NOS3 haplotype, homozygotes for haplotype A-non4r-Asp had 6.1% higher %BF. Significant interactions were revealed between the ADRB2 Arg16Gly SNP and VPA on VAT, SAAT and waist circumference (WC) such that Gly16 homozygotes may benefit less from increased VPA to reduce their weight. Genetic susceptibility to increased general and central adiposity is dependent on several factors, such as SES and vigorous exercise. Improved understanding of the joint effect of genes and lifestyle on adiposity will offer new insights into obesity and may provide new avenues for personalized prevention and treatment.

Common variants near melanocortin 4 receptor are associated with general and visceral adiposity in European- and African-American youth

OBJECTIVE

Recent genome-wide association studies found common variants near the melanocortin 4 receptor gene associated with obesity. This study aimed to assess the influence of the identified single nucleotide polymorphisms rs17782313 and rs17700633 on general and visceral adiposity in European- and African-American youth.

STUDY DESIGN

In 1890 youth (49.1% European-American, 45.6% male, mean age 16.7 years), we examined the associations of the rs17782313 and rs17700633 with anthropometry, percent body fat, visceral adipose tissue, and subcutaneous abdominal adipose tissue. Interaction of the single nucleotide polymorphisms with ethnicity or sex was investigated and haplotype analyses conducted.

RESULTS

Rs17782313 was significantly associated with weight (P = .02) and waist circumference (P = .03) in all subjects and with body mass index (P = .002) in females. In females rs17700633 was significantly associated with percent body fat (P = .001), visceral adipose tissue (P < .001), and subcutaneous abdominal adipose tissue (P < .001). Rs17700633 was significantly associated with fasting insulin and homeostasis model assessment, but the significance attenuated after adjustment for percent body fat. These findings were confirmed by haplotype analysis. No significant interactions of the variants with ethnicity were found for any of these phenotypes.

CONCLUSIONS

The relatively large effect of these common variants near melanocortin 4 receptor on general and visceral adiposity in childhood, especially in girls, could prove helpful in elucidating the molecular mechanisms underlying the development of obesity in early life.

Association study of AMP-activated protein kinase subunit genes in polycystic ovary syndrome

OBJECTIVE

To examine the genes for AMP-activated protein kinase (AMPK) subunits alpha2 (PRKAA2) and gamma3 (PRKAG3) as candidates for polycystic ovary syndrome (PCOS) and its component traits.

DESIGN AND METHODS

A total of 287 white PCOS women were recruited from the reproductive endocrinology clinic at the University of Alabama at Birmingham and 187 white control subjects were recruited from the surrounding community. Seven PRKAA2 single nucleotide polymorphisms (SNPs) and four PRKAG3 SNPs were genotyped in PCOS cases and controls. Genotyping and association analysis were performed at Cedars-Sinai Medical Center.

RESULTS

Nominal associations of PRKAA2 variants with insulin-related traits and the PRKAG3 Pro71Ala variant with PCOS were not statistically significant after multiple testing correction. Among PCOS patients, there were no associations between variants in AMPK subunit genes and androgenic or reproductive traits.

CONCLUSIONS

Variants in genes for AMPKalpha2 and AMPKgamma3 were not associated with PCOS or its component traits. Our evidence does not demonstrate that AMPK is a major genetic risk factor for PCOS.

AMPK in Health and Disease

The function and survival of all organisms is dependent on the dynamic control of energy metabolism, when energy demand is matched to energy supply. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals that control energy balance through the regulation of multiple biochemical pathways in all eukaryotes. In this review, we begin with the discovery of the AMPK family and discuss the recent structural studies that have revealed the molecular basis for AMP binding to the enzyme's gamma subunit. AMPK's regulation involves autoinhibitory features and phosphorylation of both the catalytic alpha subunit and the beta-targeting subunit. We review the role of AMPK at the cellular level through examination of its many substrates and discuss how it controls cellular energy balance. We look at how AMPK integrates stress responses such as exercise as well as nutrient and hormonal signals to control food intake, energy expenditure, and substrate utilization at the whole body level. Lastly, we review the possible role of AMPK in multiple common diseases and the role of the new age of drugs targeting AMPK signaling.

Genetic-epidemiological evidence on genes associated with HDL cholesterol levels: a systematic in-depth review

High-density lipoprotein (HDL) particles exhibit multiple antiatherogenic effects. They are key players in the reverse cholesterol transport which shuttles cholesterol from peripheral cells (e.g. macrophages) to the liver or other tissues. This complex process is thought to represent the basis for the antiatherogenic properties of HDL particles. The amount of cholesterol transported in HDL particles is measured as HDL cholesterol (HDLC) and is inversely correlated with the risk for coronary artery disease: an increase of 1mg/dL of HDLC levels is associated with a 2% and 3% decrease of the risk for coronary artery disease in men and women, respectively. Genetically determined conditions with high HDLC levels (e.g. familial hyperalphalipoproteinemia) often coexist with longevity, and higher HDLC levels were found among healthy elderly individuals. HDLC levels are under considerable genetic control with heritability estimates of up to 80%. The identification and characterization of genetic variants associated with HDLC concentrations can provide new insights into the background of longevity. This review provides an extended overview on the current genetic-epidemiological evidence from association studies on genes involved in HDLC metabolism. It provides a path through the jungle of association studies which are sometimes confusing due to the varying and sometimes erroneous names of genetic variants, positions and directions of associations. Furthermore, it reviews the recent findings from genome-wide association studies which have identified new genes influencing HDLC levels. The yet identified genes together explain only a small amount of less than 10% of the HDLC variance, which leaves an enormous room for further yet to be identified genetic variants. This might be accomplished by large population-based genome-wide meta-analyses and by deep-sequencing approaches on the identified genes. The resulting findings will probably result in a re-drawing and extension of the involved metabolic pathways of HDLC metabolism.

Single nucleotide polymorphisms in genes encoding LKB1 (STK11), TORC2 (CRTC2) and AMPK alpha2-subunit (PRKAA2) and risk of type 2 diabetes

The LKB1-AMPK-TORC2 signaling pathway controls glucose homeostasis in the liver, and mediates therapeutic effects of insulin-sensitizing antidiabetic agents. To examine whether genetic variations in genes encoding components of this signaling pathway contribute to increased susceptibility to type 2 diabetes, we screened STK11 (LKB1) and CRTC2 (TORC2) genes for genetic variants and conducted a case-control study in 1787 unrelated Japanese individuals. Additionally, the previously described association between the PRKAA2 (AMPK alpha2-subunit) haplotype and type 2 diabetes was tested for replication. We observed associations of nominal significance with two SNPs, an intronic SNP in the STK11 (rs741765; OR 1.33, 95% CI 1.05-1.67, p=0.017, under a recessive genetic model), and a non-synonymous SNP in the CRTC2 (6909C>T: Arg379Cys; OR 3.01, 95% CI 1.18-7.66, p=0.016, under a dominant model), although neither withstood correction for multiple testing. We were unable to replicate the association between the PRKAA2 haplotype and type 2 diabetes: however, in the single SNP evaluation, an intronic PRKAA2 SNP (rs1418442) that had previously been reported to be associated with serum cholesterol levels in Caucasian females showed a weak association (OR 0.62, 95% CI 0.40-0.96, p=0.030, under a recessive model). Among the three genes investigated herein, gene-gene (SNP-SNP) interaction studies provided evidence for an interaction between STK11 and CRTC2 influencing susceptibility to type 2 diabetes. Our findings suggest that genetic variants of LKB1-AMPK-TORC2 pathway components may exert a weak influence on the occurrence of type 2 diabetes in Japanese.

Role of AMP-activated protein kinase gamma 3 genetic variability in glucose and lipid metabolism in non-diabetic whites

AIMS/HYPOTHESIS

AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that acts as an intracellular fuel sensor, directing multiple metabolic pathways in a catabolic direction in times of nutrient shortage. In humans, three different gamma-subunits (gamma(1), gamma(2), gamma(3)) have been identified as AMPK regulators. The AMPKgamma3 (protein kinase, AMP-activated, gamma 3 non-catalytic subunit, PRKAG3) isoform plays a role in gene regulation in glucose/lipid metabolism and skeletal muscle glycogen content. We investigated whether PRKAG3, in addition to being expressed in skeletal muscle, is also expressed in human liver. We also investigated whether genetic variance in PRKAG3 is associated with glucose and/or lipid metabolism in non-diabetic whites.

MATERIALS AND METHODS

After sequencing a screening cohort (n = 50) in the PRKAG3 locus, we genotyped 1061 participants for frequently found single nucleotide polymorphisms (SNPs). Association analyses between genotypes/haplotypes and metabolic traits were carried out.

RESULTS

We detected PRKAG3 expression in human liver and skeletal muscle. Two SNPs (rs692243, rs6436094) with minor allele frequencies of 0.16 and 0.26 respectively and in moderate linkage disequilibrium (D' = 0.92; r (2) = 0.47) were found. rs692243 (C/G) confers a Pro71Ala mutation, while rs6436094 (A/G) is located in the 3' untranslated region. No associations with prediabetic traits such as body fat distribution, insulin resistance or insulin secretion were found (p > 0.15 for all). However, the minor alleles of both SNPs were significantly associated with higher serum LDL-cholesterol and apolipoprotein (Apo) B-100 levels (rs692243: CG:LDL 4.3%, ApoB-100 3.4%; GG:LDL 7.6%, ApoB-100 5.4%; p = 0.008 and p = 0.01 respectively; rs6436094: AG:LDL 3.3%, ApoB-100 1.7%; GG:LDL 11.3%, ApoB-100 11.1%; p = 0.009 and p = 0.05 respectively; dominant model). The GG/GG diplotype homozygous for both minor SNP alleles displayed the highest LDL-cholesterol among all frequent diplotypes (p = 0.059).

CONCLUSIONS/INTERPRETATION

While genetic variability in PRKAG3 does not seem to have a major effect on glucose metabolism, it may play an important role in lipoprotein metabolism in humans.

AMP-Activated Protein Kinase in the Heart

AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that is expressed in most mammalian tissues including cardiac muscle. Among the multiple biological processes influenced by AMPK, regulation of fuel supply and energy-generating pathways in response to the metabolic needs of the organism is fundamental and likely accounts for the remarkable evolutionary conservation of this enzyme complex. By regulating the activity of acetyl-coenzyme A carboxylase, AMPK affects levels of malonyl-coenzyme A, a key energy regulator in the cell. AMPK is generally quiescent under normal conditions but is activated in response to hormonal signals and stresses sufficient to produce an increase in AMP/ATP ratio, such as hypoglycemia, strenuous exercise, anoxia, and ischemia. Once active, muscle AMPK enhances uptake and oxidative metabolism of fatty acids as well as increases glucose transport and glycolysis. Data from AMPK deficiency models suggest that AMPK activity might influence the pathophysiology and therapy of diabetes and increase heart tolerance to ischemia. Effects that are not as well understood include AMPK regulation of transcription. Different AMPK isoforms are found in distinct locations within the cell and have distinct functions in different tissues. A principal mode of AMPK activation is phosphorylation by upstream kinases (eg, LKB1). These kinases have a fundamental role in cell-cycle regulation and protein synthesis, suggesting involvement in a number of human disorders including cardiac hypertrophy, apoptosis, cancer, and atherosclerosis. The physiological role played by AMPK during health and disease is far from being clearly defined. Naturally occurring mutations affecting the nucleotide-sensing modules in the regulatory gamma subunit of AMPK lead to enzyme dysregulation and inappropriate activation under resting conditions. Glycogen accumulation ensues, leading to human disease manifesting as cardiac hypertrophy, accessory atrioventricular connections, and degeneration of the physiological conduction system. Whether AMPK is a key participant or bystander in other disease states and whether its selective manipulation may significantly benefit these conditions remain important questions.