Apolipoprotein E polymorphism and the relationships of physical fitness to plasma lipoprotein-lipid levels in men and women

Effects of Apolipoprotein E ɛ4 and Risk Factors on Domains of Cognition in Mild Cognitive Impairment and Dementia

BACKGROUND

The apolipoprotein E (APOE) gene is the most potent genetic risk factor for dementia. However, there are few studies on how the APOE gene affects cognitive domain functions.

OBJECTIVE

This study aimed to investigate the effects of risk factors for dementia on cognitive function in patients with mild cognitive impairment and Alzheimer's disease (AD).

METHODS

This study included subjects whose Clinical Dementia Rating scores ranged from 0.5 to 2 and who were older than 65 years. Risk factors for dementia included the APOE ɛ4 allele, age, education period, employment period, body mass index, and exercise. APOE genotyping was performed by polymerase chain reaction, and other factors were identified using medical charts or structured checklists. Cognitive function was measured using the Seoul Neuropsychological Screening Battery II.

RESULTS

General cognitive function did not show a significant difference according to APOE ɛ4 status. However, the score for delayed verbal memory was lower in the APOE ɛ4-carrier group than in the non-carrier group (p < 0.05). In addition, age, education period, employment period, and exercise were correlated with different cognitive function domains in the non-carrier group (p < 0.05); however, the carrier group was showed a significant correlation between age, body mass index, and cognitive domains.

CONCLUSION

Our findings suggest that APOE ɛ4 significantly decreases verbal memory in patients with AD. Moreover, the effects of risk factors on cognitive function were significantly different according to the APOE ɛ4 status.

Apolipoprotein E Genotype Moderation of the Association Between Physical Activity and Brain Health. A Systematic Review and Meta-Analysis

Introduction

Possession of one or two e4 alleles of the apolipoprotein E (APOE) gene is associated with cognitive decline and dementia risk. Some evidence suggests that physical activity may benefit carriers of the e4 allele differently.

Method

We conducted a systematic review and meta-analysis of studies which assessed APOE differences in the association between physical activity and: lipid profile, Alzheimer's disease pathology, brain structure and brain function in healthy adults. Searches were carried out in PubMed, SCOPUS, Web of Science and PsycInfo.

Results

Thirty studies were included from 4,896 papers screened. Carriers of the e4 allele gained the same benefit from physical activity as non-carriers on most outcomes. For brain activation, e4 carriers appeared to gain a greater benefit from physical activity on task-related and resting-state activation and resting-state functional connectivity compared to non-carriers. Post-hoc analysis identified possible compensatory mechanisms allowing e4 carriers to maintain cognitive function.

Discussion

Though there is evidence suggesting physical activity may benefit e4 carriers differently compared to non-carriers, this may vary by the specific brain health outcome, perhaps limited to brain activation. Further research is required to confirm these findings and elucidate the mechanisms.

Trefoil Factor Family Member 2: From a High-Fat-Induced Gene to a Potential Obesity Therapy Target

Obesity has its epidemiological patterns continuously increasing. With controlling both diet and exercise being the main approaches to manage the energy metabolism balance, a high-fat (HF) diet is of particular importance. Indeed, lipids have a low satiety potential but a high caloric density. Thus, focusing on pharmacologically targetable pathways remains an approach with promising therapeutic potential. Within this context, trefoil factor family member 2 (Tff2) has been characterized as specifically induced by HF diet rather than low-fat diet. TFF2 has also been linked to diverse neurological mechanisms and metabolic patterns suggesting its role in energy balance. The hypothesis is that TFF2 would be a HF diet-induced signal that regulates metabolism with a focus on lipids. Within this review, we put the spotlight on key findings highlighting this line of thought. Importantly, the hypothetical mechanisms pointed highlight TFF2 as an important contributor to obesity development via increasing lipids intestinal absorption and anabolism. Therefore, an outlook for future experimental activities and evaluation of the therapeutic potential of TFF2 inhibition is given. Indeed, its knockdown or downregulation would contribute to an antiobesity phenotype. We believe this work represents an addition to our understanding of the lipidic molecular implications in obesity, which will contribute to develop therapies aiming to manage the lipidic metabolic pathways including the absorption, storage and metabolism via targeting TFF2-related pathways. We briefly discuss important relevant concepts for both basic and clinical researchers.

Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study

Background

Several longitudinal studies found an inverse relationship between levels of physical activity and cognitive decline, dementia, and/or Alzheimer's disease (AD), but results have been inconsistent. We followed an older, community-based cohort for over a decade to examine the association of physical activity with the risk of incident dementia and subclinical brain MRI markers of dementia.

Methods

The physical activity index (PAI) was assessed in the Framingham Study Original and Offspring cohorts, aged 60 years or older. We examined the association between PAI and risk of incident all-cause dementia and AD in participants of both cohorts who were cognitively intact and had available PAI (n = 3,714; 54% women; mean age = 70±7 years). We additionally examined the association between PAI and brain MRI in the Offspring cohort (n = 1,987).

Results

Over a decade of follow-up, 236 participants developed dementia (188 AD). Participants in the lowest quintile of PAI had an increased risk of incident dementia compared with those in higher quintiles (hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.04-1.97, p = .028) in a multivariable-adjusted model. Secondary analysis revealed that this relation was limited to participants who were apolipoprotein (APO)E ε4 allele noncarriers (HR = 1.58, 95% CI = 1.08-2.32; p = .018) and strongest in participants aged 75 years or older. PAI was also linearly related to total brain and hippocampal volumes (β ± SE = 0.24±0.06; p < .01 and 0.004±0.001; p = .003, respectively).

Conclusion

Low physical activity is associated with a higher risk for dementia in older individuals, suggesting that a reduced risk of dementia and higher brain volumes may be additional health benefits of maintaining physical activity into old age.

The role of apolipoprotein E polymorphism in improving dyslipidemia in obese adolescents following physical exercise and National Cholesterol Education Program Step II intervention

BACKGROUND

Lifestyle changes are important factors for managing dyslipidemia before considering blood lipid-lowering drugs. However, genetic factors can influence the response outcome.

OBJECTIVE

We aimed to determine a dyslipidemia management strategy in obese adolescents.

PATIENTS AND METHODS

A total of 60 dyslipidemic obese adolescents received physical exercise and the NCEP step II diet for 28 days. Apolipoprotein E (apo E) genotypes and blood lipid levels were compared before and after interventions.

RESULTS

The apo E3/E3 genotype was found to be common in all subjects. Mean levels of total cholesterol, triglyceride, and low-density lipoprotein-cholesterol (LDL-C) improved in subjects with the E3 allele after the intervention, but not the E2 allele. Total cholesterol and LDL-C, but not triglyceride levels, improved in subjects with the E4 allele.

DISCUSSION

Apo E alleles might influence improvement in lipid profiles after diet and exercise interventions. These results could inform personalized dyslipidemia management in obese adolescents, to determine which subjects would benefit from blood lipid-lowering drugs.

Association of apolipoprotein E polymorphism with maximal oxygen uptake after exercise training: a study of Chinese young adult

Background

Although a few studies have been conducted, it is still unclear whether the apolipoprotein E (APOE) polymorphism is associated with maximal oxygen uptake (VO_2max) after exercise training. The objective of this study was to examine if the APOE gene polymorphisms affect VO_2max after exercise training in Chinese young adult.

Methods

A total of 360 Chinese young adult (180 male and 180 female) were recruited into this gender-specific cohorts. Anthropometrics, serum lipids, and VO_2max were measured pre and post 6 months of supervised exercise training. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay was applied to assess the APOE gene polymorphisms.

Results

VO_2max after exercise training increased significantly higher in carriers of E2/E3 in male [odds ratio (OR) =0.68, 95% confidence interval (CI) = 0.04, 1.32; P = 0.04] and female (OR =0.62, 95% CI = 0.05, 1.18; P = 0.03). VO_2max after exercise training increased significantly higher in carriers of E3/E4 in male (OR =0.60, 95% CI = 0.09, 1.11; P = 0.02) and female (OR =0.62, 95% CI = 0.09, 1.15; P = 0.02). No significant differences were found in carriers of E2/E2, E2/E4, E3/E3, E4/E4 in either male nor female.

Conclusion

Our study found that APOE gene polymorphism was associated with VO_2max levels after exercise training in Chinese young adult. In the future, further experiments will be necessary to confirm this finding and to find the possible mechanism.

Interaction of apolipoprotein E genotype with smoking and physical inactivity on coronary heart disease risk in men and women

OBJECTIVE

Apolipoprotein E genotype (APOE) polymorphism affects lipid levels and coronary heart disease (CHD) risk. However, these associations may be modified by lifestyle factors. Therefore, we studied whether smoking, physical inactivity or overweight interact with APOE on cholesterol levels and CHD risk.

METHODS

Combining two Swedish case-control studies yielded 1735 CHD cases and 4654 population controls (3747 men, 2642 women). Self-reported questionnaire lifestyle data included smoking (ever [current or former regular] or never) and physical inactivity (mainly sitting leisure time). We obtained LDL cholesterol levels and APOE genotypes. CHD risk was modelled using logistic regression to obtain odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for relevant covariates.

RESULTS

Smoking interacted with APOE on CHD risk; adjusted ORs for ever versus never smoking were 1.45 (95% CI 1.00-2.10) in ɛ2 carriers, 2.25 (95% CI 1.90-2.68) in ɛ3 homozygotes and 2.37 (95% CI 1.85-3.04) in ɛ4 carriers. Female ɛ4 carriers had OR 3.62 (95% CI 2.32-5.63). The adjusted ORs for physical inactivity were 1.09 (95% CI 0.73-1.61), 1.34 (95% CI 1.12-1.61), and 1.79 (95% CI 1.38-2.30) in ɛ2, ɛ3ɛ3 and ɛ4 groups, respectively. No interaction was seen between overweight and APOE for CHD risk, or between any lifestyle factor and APOE for LDL cholesterol levels.

CONCLUSION

The APOE ɛ2 allele counteracted CHD risk from smoking in both genders, while the ɛ4 allele was seen to potentiate this risk mainly in women. Similar ɛ2 protection and ɛ4 potentiation was suggested for CHD risk from physical inactivity.

Do genetic variations alter the effects of exercise training on cardiovascular disease and can we identify the candidate variants now or in the future?

Cardiovascular disease (CVD) and CVD risk factors are highly heritable, and numerous lines of evidence indicate they have a strong genetic basis. While there is nothing known about the interactive effects of genetics and exercise training on CVD itself, there is at least some literature addressing their interactive effect on CVD risk factors. There is some evidence indicating that CVD risk factor responses to exercise training are also heritable and, thus, may have a genetic basis. While roughly 100 studies have reported significant effects of genetic variants on CVD risk factor responses to exercise training, no definitive conclusions can be generated at the present time, because of the lack of consistent and replicated results and the small sample sizes evident in most studies. There is some evidence supporting “possible” candidate genes that may affect these responses to exercise training: APO E and CETP for plasma lipoprotein-lipid profiles; eNOS, ACE, EDN1, and GNB3 for blood pressure; PPARG for type 2 diabetes phenotypes; and FTO and BAR genes for obesity-related phenotypes. However, while genotyping technologies and statistical methods are advancing rapidly, the primary limitation in this field is the need to generate what in terms of exercise intervention studies would be almost incomprehensible sample sizes. Most recent diabetes, obesity, and blood pressure genetic studies have utilized populations of 10,000–250,000 subjects, which result in the necessary statistical power to detect the magnitude of effects that would probably be expected for the impact of an individual gene on CVD risk factor responses to exercise training. Thus at this time it is difficult to see how this field will advance in the future to the point where robust, consistent, and replicated data are available to address these issues. However, the results of recent large-scale genomewide association studies for baseline CVD risk factors may drive future hypothesis-driven exercise training intervention studies in smaller populations addressing the impact of specific genetic variants on well-defined physiological phenotypes.

Interactive effects of APOE haplotype, sex, and exercise on postheparin plasma lipase activities

Hepatic lipase (HL) and lipoprotein lipase (LPL) activities (HLA, LPLA) modify lipoproteins and facilitate their binding to hepatic receptors. Apolipoprotein E (APOE) physically interacts with the lipases, and the three common haplotypes of the APOE gene (ε2, ε3, and ε4) yield protein isoforms (E2, E3, and E4, respectively) that are functionally different. Lipase activities themselves differ by sex and exercise training status. The interaction of APOE genotype, exercise training, and sex effects on lipase activities has not been studied. We measured postheparin plasma lipase activities in normolipidemic men and women with the three most common APOE genotypes, which are the haplotype combinations ε2/ε3 (n = 53 ), ε3/ε3 (n = 62), and ε4/ε3 (n = 52), enrolled in 6 mo of aerobic exercise training. These haplotype combinations comprise an estimated 11.6, 62.3, and 21.3% of the population, respectively. Baseline HLA was 35% lower in women than in men (P < 0.0001). In men but not women, HLA was higher in ε2/ε3 group compared with ε4/ε3 (P = 0.01) and ε3/ε3 (P = 0.05). Neither sex nor APOE genotype affected baseline LPLA. Training decreased HLA by 5.2% (P = 0.018) with no APOE effect. The apparent increase in LPLA following exercise was significant and APOE dependent only when corrected for baseline insulin (P < 0.05). Exercise decreased LPLA by 0.8 μmol free fatty acid (FFA)·ml⁻¹·h⁻¹ (-6%) in ε3/ε3 compared with the combined increases of 6.6% in ε2/ε3 and 12% in ε4/ε3 (P = 0.018 vs. ε3/ε3). However, these differences were statistically significant only after correcting for baseline insulin. We conclude that common APOE genotypes interact with 1) sex to modulate HLA regardless of training status, with ε2/ε3 men demonstrating higher HLA than ε3/ε3 or ε4/ε3 men, and 2) aerobic training to modulate LPLA, regardless of sex, with ε3/ε3 subjects showing a significant decrease compared with an increase in ε2/ε3 and ε3/ε4 after controlling for baseline insulin.

Physical activity and Alzheimer's disease: from prevention to therapeutic perspectives

A number of factors, including physical activity, may contribute to prevention of cognitive decline and delay the onset of dementia. In addition to its convincing multiple benefits, an increasing body of evidence suggests that an active life has a protective effect on brain functioning in elders. Physical activity may also slow down the course of Alzheimer's disease. These hypotheses have led to increasing research in this specific area during the past decade. This review systematically analyzes the current literature on Alzheimer's disease and the effect of physical activity. Epidemiological studies, short-term randomized controlled trials (RCTs) in nondemented participants, and biological research suggest that physical activity improves cognitive function in older subjects. The limitations of these works are discussed. No RCTs have yet demonstrated that regular physical activity prevents dementia. Additional challenging clinical interventional studies are needed to demonstrate this relationship, but accumulating evidence from biological research is available. Defining the optimal preventive and therapeutic strategies in terms of type, duration, and intensity of physical activity remain an open question. In the future, the prevention of Alzheimer's disease may be based on rules governing lifestyle habits such as diet, cognitive activity, and physical activity.

Managing abnormal blood lipids: a collaborative approach

Current data and guidelines recommend treating abnormal blood lipids (ABL) to goal. This is a complex process and requires involvement from various healthcare professionals with a wide range of expertise. The model of a multidisciplinary case management approach for patients with ABL is well documented and described. This collaborative approach encompasses primary and secondary prevention across the lifespan, incorporates nutritional and exercise management as a significant component, defines the importance and indications for pharmacological therapy, and emphasizes the importance of adherence. Use of this collaborative approach for the treatment of ABL ultimately will improve cardiovascular and cerebrovascular morbidity and mortality.

APOE haplotypes influence bone mineral density in Caucasian males but not females

Low bone mineral density (BMD) is one of the most important risk factors for osteoporosis. Apolipoprotein E (APOE) has been considered as a candidate gene for osteoporosis because of its influence on osteoblast uptake of lipoprotein-borne vitamin K. Using the quantitative transmission disequilibrium test QTDT, we examined linkage and/or association of APOE and BMD at the lumbar spine and the total hip in a sample of 387 Caucasian nuclear families with 715 parents and 953 children. The children were aged 20-50 years and female offspring were premenopausal as well. Four single nucleotide polymorphisms (SNP1-4) in the APOE gene, 4-locus haplotypes and 2-locus haplotypes (epsilon1, epsilon2, epsilon3, epsilon4 isoforms, reconstructed by SNP3 and SNP4) were analyzed. In the whole sample and the female offspring families we found no evidence of linkage or association for either single SNP or haplotype with BMD at the two studied skeletal sites. In the male offspring families, within-family associations were observed at the haplotypes CGTC (P = 0.001), GGTT (P = 0.002), and GATC (P = 0.006) for the lumbar spine BMD, and GATC (P = 0.008) for the total hip BMD. These data suggested that in our studied Caucasian population, APOE may have effects on BMD variation in males but not females. Further studies with a larger sample size are required to confirm such results.

Association of apolipoprotein E polymorphism with blood lipids and maximal oxygen uptake in the sedentary state and after exercise training in the HERITAGE family study

The relationship of apolipoprotein E (apo E) genotypes to plasma lipid and maximal oxygen uptake (Vo(2max)) was studied in the sedentary state and after a supervised exercise training program in black and white men and women. At baseline, the apo E 2/3 genotype was associated with the lowest, and apo E 3/4 and E4/4 with the highest low-density liporpotein (LDL) cholesterol and apo B levels in men and women of both races, while female (not male) carriers of apo E3 had higher high-density lipoprotein (HDL) cholesterol levels than carriers of other genotypes. Very-low-density lipoprotein (VLDL) cholesterol and triglyceride levels were significantly higher in carriers of both apo E2 and apo E4 in white men only. Racial and sex differences were noted in lipid responses to exercise training across genotypes with a significantly greater increase in HDL cholesterol observed only in white female carriers of apo E 2/3 and E3/3, as compared to apo E4/4. Apo E polymorphism was not found to be associated with Vo(2max) levels either in the sedentary state nor the Vo(2max) response to exercise training, contrary to previous reports.

Physical activity modulates effects of some genetic polymorphisms affecting cardiovascular risk in men aged over 40 years

BACKGROUND AND AIM

Several genetic polymorphisms have been found to be involved in cardiovascular risk, and many studies have documented the beneficial effect of systematic physical activity (PA) on the cardiovascular system. Our aim was to investigate the interactive effects of PA and genetic background on plasma lipids and homocysteine (tHcy) levels.

METHODS AND RESULTS

Clinical and metabolic parameters, dietary intakes and some polymorphisms of the genes involved in cardiovascular risk (Apo E, fatty acid binding protein-2, Apo AII, hepatic lipase and methylene tetrahydrofolate reductase) were determined in 100 men aged over 40 years who cycle 120-150 Km/week and 100 age-matched sedentary controls. The physically active subjects had lower concentrations of plasma LDL cholesterol (LDL-C), triglyceride (TG), Apo B, glucose and tHcy, and higher concentrations of plasma HDL cholesterol (HDL-C) and Apo AI than the sedentary men; they also had larger LDL particle sizes (LDLs). The LDL-C and Apo B raising effect of the Apo E epsilon 4 allele detectable in the sedentary subjects was totally absent in the cyclists, in whom the LDL-C and Apo B lowering effect of the epsilon 2 allele was observed. PA blunted the TG-raising effect of the Apo AII-265TT genotype, and amplified the HDL-C raising effect of the HL-250AA genotype. PA had a small but significant lowering effect on plasma tHcy adjusted for folate levels in subjects with the 677TT genotype of the MTHFR gene.

CONCLUSIONS

Extended high-intensity PA in men aged over 40 years may modify their metabolic cardiovascular risk factors even in the presence of some unfavourable genotypes.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

Lipids, lipoproteins, and exercise

PURPOSE

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favorably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met.

METHODS AND RESULTS

Plasma triglyceride reductions are often observed after exercise training regimens requiring energy expenditures similar to those characterized to increase high-density lipoprotein cholesterol (HDL-C). Thresholds established from cross-sectional and longitudinal exercise training studies indicate that 15 to 20 miles/week of brisk walking or jogging, which elicit between 1,200 to 2,200 kcals of energy expenditure per week, is associated with triglyceride reductions of 5 to 38 mg/dL and HDL-C increases of 2 to 8 mg/dL. Exercise training seldom alters total cholesterol and low-density lipoprotein cholesterol (LDL-C) unless dietary fat intake is reduced and body weight loss is associated with the exercise training program, or both. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with energy expenditures of 1,200 to 2,200 kcals/week.

CONCLUSIONS

It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. Regarding hyperlipidemic disorders, the primary means for intervention is pharmacologic, whereas diet modification, weight loss, and exercise, although important, are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the mechanisms responsible for these changes, rehabilitation professionals can better develop a comprehensive medical management plan that optimizes pharmacologic, reduced dietary fat intake, weight loss, and exercise interventions.

The APOE locus and the pharmacogenetics of lipid response

Genetic variation at the APOE locus has been associated with plasma lipoprotein concentrations in the fasting (low-density, and high-density lipoproteins and triglycerides), and in the postprandial (triglyceride-rich lipoproteins) states. Resulting from these associations, the APOE locus has been found to be a significant genetic determinant of cardiovascular disease in the general population. Beyond the traditional association studies, APOE genetic variation has been shown to play a significant role, which explains some of the individual variations in therapies aimed at normalizing plasma lipid concentrations. Thus, the APOE E4 allele has been shown in some studies to be associated with increased response to dietary intervention. Conversely, APOE E2 carriers appear to be more responsive to statin therapy. The mechanisms behind these observations, however, have not been elucidated. Moreover, several other gene:environment and gene:therapy interactions have recently been demonstrated, thus further increasing the interest in this remarkable apolipoprotein.

Exercise in the treatment of lipid disorders

As a result of scientific evaluation, we know that exercise has a positive impact on the lipid and lipoprotein profile, and we have a greater understanding for the necessary amount of exercise needed to cause these changes. In the case of hyperlipidemic disorders, we know the primary means for intervention is pharmacological, and that diet, weight loss, and exercise are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the lipoprotein enzyme changes, future research should continue to focus on the molecular basis for these changes. For example by knowing a person's apo E genotype, we gain better comprehension as to why some individuals respond to exercise, while others do not. Another area for further investigation is the assessment of drug and exercise interaction. Presently, little is known regarding the use of lipid-lowering drugs and the impact of exercise. Finally, these investigations could provide new insights for better understanding the exercise CAD protective effects. The future challenge is to better understand the impact that regular exercise participation has in optimizing the lipid and lipoprotein profile with individuals with special lipid disorders.

The human gene map for performance and health-related fitness phenotypes

The aim of this paper is to describe the first human gene map for physical performance and health-related fitness traits based on the papers published until the end of 2000. Studies of candidate genes using case-control and other designs are reviewed. Quantitative trait loci from the limited evidence reported to date in genomic scans are also incorporated. Performance and fitness phenotypes in the sedentary state as well as their changes during exercise, if applicable, or in response to exercise training are considered. Physical performance traits include cardiorespiratory endurance indicators and muscular strength or muscular performance variables. Health-related fitness phenotypes are grouped under the following categories: hemodynamic traits; anthropometry and body composition; insulin and glucose metabolism; and lipids, lipoproteins, and hemostatic factors. A yearly update of this human gene map will be published.

Characterization of control and immobilized skeletal muscle: an overview from genetic engineering

To elucidate the molecular basis of muscle atrophy, we have performed the serial analysis of gene expression (SAGE) method with control and immobilized muscles of 10 rats. The genes that expressed >0.5% in muscle are involved in the following three functions: 1) contraction (troponin I, C and T; myosin light chain 1-3; actin; tropomyosin; and parvalbumin), 2) energy metabolism (cytochrome c oxidase I and III, creatine kinase, glyceraldehyde-3-phosphate-dehydrogenase, phosphoglycerate mutase, ATPase 6, and aldolase A), and 3) housekeeping (lens epithelial protein). Muscle atrophy appears to be caused by changes in mRNA levels of specific regulators of proteolysis, protein synthesis, and contractile apparatus assembling, such as polyubiquitin, elongation factor 2, and nebulin. Immobilization has produced a decrease more than threefold in gene expression of enzymes involved in energy metabolism, especially ATPase, cytochrome c oxidase, NADH dehydrogenase, and protein phosphatase 1. Differential gene expressions of selenoprotein W and uroporphyrinogen decarboxylase, which can be involved in oxidative stress, were also observed. Other genes with various functions, such as cholesterol metabolism and growth factors, were also differentially expressed. Moreover, novel genes regulated by immobilization were discovered. Thus, the current study allows a better understanding of global muscle characteristics and the molecular mechanisms of sedentarity and sarcopenia.

APO E gene and gene-environment effects on plasma lipoprotein-lipid levels

Apolipoprotein E (apo E) is important in plasma lipid metabolism and is a component of several plasma lipoprotein-lipid particles. Three major apo E isoforms are encoded by three common alleles at the APO E locus. The E2 allele is associated with lower and the E4 allele with higher total plasma cholesterol and LDL cholesterol levels compared with the E3 allele. Available data generally indicate that APO E2, and possibly E3, genotype individuals reduce plasma total and low-density lipoprotein (LDL) cholesterol levels more than APO E4 individuals with statin therapy. Some evidence also indicates that APO E2 individuals are more likely to respond favorably to gemfibrozil and cholestyramine. On the other hand, it appears that with probucol, APO E4 genotype individuals may improve plasma lipoprotein-lipid profiles more than APO E3 individuals. APO E2 and E3 genotype perimenopausal women appear to improve plasma lipoprotein-lipid profiles more with hormone replacement therapy than APO E4 women. On the other hand, low-fat diet interventions tend to reduce plasma LDL cholesterol and, perhaps, plasma total cholesterol levels more in APO E4 than in APO E2 or E3 individuals. Both cross-sectional and longitudinal studies generally indicate that APO E2 and E3 individuals improve plasma lipoprotein-lipid profiles more with exercise training than APO E4 individuals. Although these data are hardly definitive, they lend strong support for the possibility that in the near future individuals will be directed to what might be their optimal therapy for improving plasma lipoprotein-lipid profiles and cardiovascular disease risk based partially on APO E genotype.