Association of the Myostatin gene with obesity, abdominal obesity and low lean body mass and in non-diabetic Asian Indians in north India

Association of Myostatin Gene Polymorphisms with Strength and Muscle Mass in Athletes: A Systematic Review and Meta-Analysis of the MSTN rs1805086 Mutation

Polymorphism (rs1805086), c.458A>G, p.Lys(K)153Arg(R), (K153R) of the myostatin gene (MSTN) has been associated with a skeletal muscle phenotype (hypertrophic response in muscles due to strength training). However, there are not enough reliable data to demonstrate whether MSTN rs1805086 K and R allelic variants are valid genetic factors that can affect the strength phenotype of athletes' skeletal muscles. The aim is to conduct a systematic review and meta-analysis of the association of MSTN rs1805086 polymorphism with the strength phenotype of athletes. This study analyzed 71 research articles on MSTN and performed a meta-analysis of MSTN K153R rs1805086 polymorphism in strength-oriented athletes and a control (non-athletes) group. It was found that athletes in the strength-oriented athlete group had a higher frequency of the R minor variant than that in the control group (OR = 2.02, P = 0.05). Thus, the obtained results convincingly demonstrate that there is an association between the studied polymorphism and strength phenotype of athletes; therefore, further studies on this association are scientifically warranted.

Decreased myostatin in response to a controlled DASH diet is associated with improved body composition and cardiometabolic biomarkers in older adults: results from a controlled-feeding diet intervention study

BACKGROUND

Elevated concentrations of myostatin inhibit muscle growth, function and strength. Myostatin is a mediator of sarcopenia and is associated with insulin resistance. For this study we tested the response of a calorie-restricted Dietary Approaches to Stop Hypertension (DASH) diet on changes in myostatin, follistatin, and mystatin:follistatin ratio levels after 12 weeks in comparison to basline in adults aged 65 years and older. Furthermore we evaluated correlations between changes in myostatin, body composition and cardiometabolic biomarkers in this cohort of older adults.

METHODS

This was a controlled-feeding diet intervention study in which females (n = 17) and males (n = 11) aged 65 years and older consumed either 85 g (n = 15) or 170 g (n = 13) of fresh lean beef within a standardized DASH diet for 12-weeks. Myostatin and follistatin concentrations were measured from fasted blood samples collected at 5 timepoints throughout the 12-week feeding intervention period. Correlations were assessed between changes in myostatin and follistatin levels and measures of body composition and cardiometabolic biomarkers.

RESULTS

There were no differences (p > 0.05) in circulating myostatin or follistatin levels between the beef intake groups. However, with beef groups combined myostatin decreased by 17.6% (p = 0.006) and the myostatin-to-follistatin ratio decreased by 16.5% (p < 0.001) in response to the study diet. Decreased myostatin was positively correlated with reductions in waist circumference (R² = 0.163; p = 0.033) and fat mass (R² = 0.233; p = 0.009). There was an inverse relationship between decreased myostatin and increased strength-to-weight ratio (R² = 0.162; p = 0.034). The change in myostatin-to-follistatin ratio was associated with the change in skeletal muscle mass-to-fat mass ratio (R² = 0.176; p = 0.026). Decreased myostatin was positively correlated with reductions in total cholesterol (R² = 0.193; p = 0.012), LDL-C (R² = 0.163; p = 0.031), insulin (R² = 0.234; p = 0.009), and HOMA-IR (R² = 0.248; P = 0.007). There was no change (p > 0.05) in circulating follistatin concentrations in response to the diet intervention.

CONCLUSIONS

The outcomes from this study suggest that a calorie-restricted DASH diet has the potential to reduce myostatin concentrations in older adults. Furthermore these outcomes support interrelationships between myostatin, body composition and cardiometabolic health in adults aged 65 years and older.

TRIAL REGISTRATION

ClinicalTrials.gov; Identifier: NCT04127240 ; Registration Date: 15/10/ 2019.

Variants in the Myostatin Gene and Physical Performance Phenotype of Elite Athletes

The MSTN gene is a negative regulator of muscle growth that is attracting attention as a candidate gene for physical performance traits. We hypothesised that variants of MSTN might be associated with the status of elite athlete. We therefore sought to study the potential role of MSTN in the physical performance of athletes by analysing the whole coding sequence of the MSTN gene in a cohort of Lithuanian elite athletes (n = 103) and non-athletes (n = 127). Consequently, two genetic variants were identified: the deletion of one of three adenines in the first intron (c.373+90delA, rs11333758) and a non-synonymous variant in the second exon (c.458A>G, p.Lys(K)153Arg(R), rs1805086). Among all samples, the MSTN rs1805086 Lys(K) allele was the most common form in both groups. Homozygous genotype for the less common Arg(R) allele was identified in only one elite canoe rower, and we could find no direct association between rs1805086 and successful results in elite athletes. Surprisingly, the intronic variant (rs11333758) was abundant among all samples. The main finding was that endurance-oriented athletes had 2.1 greater odds of being MSTN deletion genotype than non-athletes (13.6% vs. 0.8%). The present study confirms the association of the polymorphism rs11333758 with endurance performance status in Lithuanian elite athletes.

About 1/3rd of north Indian patients less than 50 years of age with type 2 diabetes have high pulse wave velocity indicating high risk of atherosclerosis

BACKGROUND AND AIMS

Asian Indian patients with type 2 diabetes mellitus (T2DM) have a high cardiovascular risk even at young age. There is a need to assess this increased risk and identify atherosclerosis early so that appropriate measures for risk reduction can be taken. We aimed to study carotid-femoral pulse wave velocity (Cf-PWV), a non-invasive indicator of atherosclerosis, in patients with diabetes below 50 years of age and its correlation with markers of obesity and other cardiovascular risk factors.

METHODS

Patients (n, 299) with T2DM below 50 years of age underwent measurement of Cf-PWV by applanation tonometry. Anthropometric parameters, blood pressure, liver span, glycosylated hemoglobin, serum lipid profile, urinary microalbumin, ankle brachial index and carotid intima media thickness were measured.

RESULTS

Data show that 32.4% of patients had high Cf-PWV, with mean values higher in males than females. On stepwise multiple linear regression analysis, the significant independent determinants of PWV were age, systolic blood pressure, waist circumference, microalbumin and liver span.

CONCLUSION

About one third patients with T2DM less than 50 years of age, in north India have increased arterial stiffness which correlates with blood pressure, abdominal obesity, liver size and microalbumin, indicating increased risk for coronary artery disease.

The myostatin rs1805086 variant is associated with obesity in Mexican adults, independently of metabolic risk factors

AIM

To determine whether rs1805086 is associated with obesity and metabolic disturbances in a Mexican adult population.

SUBJECTS AND METHODS

We genotyped rs1805086 in 1024 men and women aged 18-58 years. Anthropometric and body fat data were used to estimate obesity. Biochemical parameters were measured and DNA was used to determine the rs1805086 genotype.

RESULTS

rs1805086 heterozygous AG frequency was 5.4%, and the homozygous for the risk allele GG was absent. Heterozygous had higher levels of body mass index (BMI) and waist/height ratio (WHtR). Heterozygous subjects showed a greater total and central obesity compared to the homozygous for ancestral allele AA (OR BMI > 30 kg/m² ₌ 2.35, 95% CI 1.29-4.29; OR WHtR > 0.5 = 2.03, 95% CI 1.19-3.45; OR elevated fat mass (EFM) %= 1.72, 95% CI 1.01-2.92; OR fat mass index (FMI)>p85 = 1.96, 95% CI 1.05-3.68). rs1805086 was not associated with metabolic alterations.

CONCLUSION

Heterozygosity for rs1805086 showed a predisposition to having elevated overall and central obesity parameters. This association with adiposity seems to be independent of metabolic risk.

Sarcopenic obesity: Myokines as potential diagnostic biomarkers and therapeutic targets?

Sarcopenic obesity (SO) is a condition characterized by the occurrence of both sarcopenia and obesity and imposes a heavy burden on the health of the elderly. Controversies and challenges regarding the definition, diagnosis and treatment of SO still remain because of its complex pathogenesis and limitations. Over the past few decades, numerous studies have revealed that myokines secreted from skeletal muscle play significant roles in the regulation of muscle mass and function as well as metabolic homeostasis. Abnormalities in myokines may trigger and promote the pathogenesis underlying age-related and metabolic diseases, including obesity, sarcopenia, type 2 diabetes (T2D), and SO. This review mainly focuses on the role of myokines as potential biomarkers for the early diagnosis and therapeutic targets in SO.

Myostatin A55T Genotype is Associated with Strength Recovery Following Exercise-Induced Muscle Damage

Myostatin A55T genotype is one of the candidates showing inter-individual variation in skeletal muscle phenotypes. The aim of this study was to investigate the effect of the myostatin A55T genotype on markers of muscle damage after eccentric exercise. Forty-eight young, healthy male college students (age = 24.8 ± 2.2 years, height = 176.7 ± 5.3 cm, weight = 73.7 ± 8.3 kg) were enrolled in this study, and muscle damage was induced through 50 reps of maximal eccentric muscle contraction. As markers of muscle damage, maximal isometric strength (MIS), muscle soreness, creatine kinase (CK), and aspartate transaminase (AST) were measured. Myostatin A55T genotypes were classified into homozygous myostatin A55T allele (AA, n = 34, 72%), heterozygous myostatin A55T allele (AT, n = 13, 26%), and homozygous mutant carriers (TT, n = 1, 2%). After eccentric exercise, the subjects with heterozygous for AT showed markedly quicker MIS recovery compared to the AA group (p = 0.042). However, there were no significant variations in muscle soreness (p = 0.379), CK (p = 0.955), and AST (p = 0.706) among the groups. These results suggest that AT in myostatin A55T genotype may be associated with quicker strength recovery following exercise-induced muscle damage.

Vitamin D Supplementation in Overweight/obese Asian Indian Women with Prediabetes Reduces Glycemic Measures and Truncal Subcutaneous Fat: A 78 Weeks Randomized Placebo-Controlled Trial (PREVENT-WIN Trial)

Vitamin D deficiency may contribute to etiology of type 2 diabetes in Asian Indians. The objectives of this study was to evaluate effect of vitamin D supplementation on glycemic profile and body composition in prediabetic and vitamin D deficient overweight/obese Asian Indian women. In this open-label randomized placebo-controlled trial (78 weeks duration), 121 females (aged 20–60 years) with prediabetes and vitamin D deficiency were randomly allocated in intervention (n, 61) and placebo (n, 60) groups. The primary outcome variables were fasting blood glucose (FBG), 2-h blood glucose post OGTT (2-h BG), hemoglobin A1c (HbA1C), and reversal to normoglycemia. In Intention-to-treat analysis, at the end of intervention, we observed significant decrease in FBG [−5.0 (−12.6–2.4), p = 0.04], 2-h blood glucose post OGTT [−11(−49.3–26.9), p = 0.02], hemoglobin A1c [−0.41 (5.89, 6.55), p = 0.05] and increase in 25(OH) D [7.5 (−6.0–20.9), p = 0.002] levels in intervention as compared to the placebo group. Changes in glycemic category based on FBG were as follows; intervention group: normal FBG, 58.6%; impaired fasting glucose (IFG), 39%; and type 2 diabetes mellitus (T2DM), 2.4%; placebo group: normal FBG, 48.8%; IFG, 46.3%; and T2DM, 4.9%. Changes in category of 2-hour glucose post OGTT after intervention were as follows; intervention group: normal glucose tolerance (NGT) 51.2% and prediabetes, 48.8%; placebo group: NGT, 43.9%; prediabetes, 53.7% and T2DM, 2.4%. After intervention, subscapular skinfold (visit I^st compared to visit III^rd) and suprailiac skinfold (visit II^nd compared to visit III^rd) were significantly lower in intervention group vs. control group. In conclusion, we observed significant reduction in FBG, 2-hour glucose post OGTT, HbA1c, and truncal subcutaneous fat and reversal to normoglycemia in overweight/obese prediabetic vitamin D deficient Asian Indian women after 78 weeks of vitamin D supplementation.

Ancient origins of low lean mass among South Asians and implications for modern type 2 diabetes susceptibility

Living South Asians have low lean tissue mass relative to height, which contributes to their elevated type 2 diabetes susceptibility, particularly when accompanied by obesity. While ongoing lifestyle transitions account for rising obesity, the origins of low lean mass remain unclear. We analysed proxies for lean mass and stature among South Asian skeletons spanning the last 11,000 years (n = 197) to investigate the origins of South Asian low lean mass. Compared with a worldwide sample (n = 2,003), South Asian skeletons indicate low lean mass. Stature-adjusted lean mass increased significantly over time in South Asia, but to a very minor extent (0.04 z-score units per 1,000 years, adjusted R2 = 0.01). In contrast stature decreased sharply when agriculture was adopted. Our results indicate that low lean mass has characterised South Asians since at least the early Holocene and may represent long-term climatic adaptation or neutral variation. This phenotype is therefore unlikely to change extensively in the short term, so other strategies to address increasing non-communicable disease rates must be pursued.

Beyond the Big Five: Investigating Myostatin Structure, Polymorphism and Expression in Camelus dromedarius

Myostatin, a negative regulator of skeletal muscle mass in animals, has been shown to play a role in determining muscular hypertrophy in several livestock species, and a high degree of polymorphism has been previously reported for this gene in humans and cattle. In this study, we provide a characterization of the myostatin gene in the dromedary (Camelus dromedarius) at the genomic, transcript and protein level. The gene was found to share high structural and sequence similarity with other mammals, notably Old World camelids. 3D modeling highlighted several non-conservative SNP variants compared to the bovine, as well as putative functional variants involved in the stability of the myostatin dimer. NGS data for nine dromedaries from various countries revealed 66 novel SNPs, all of them falling either upstream or downstream the coding region. The analysis also confirmed the presence of three previously described SNPs in intron 1, predicted here to alter both splicing and transcription factor binding sites (TFBS), thus possibly impacting myostatin processing and/or regulation. Several putative TFBS were identified in the myostatin upstream region, some of them belonging to the myogenic regulatory factor family. Patterns of SNP distribution across countries, as suggested by Bayesian clustering of the nine dromedaries using the 69 SNPs, pointed to weak geographic differentiation, in line with known recurrent gene flow at ancient trading centers along caravan routes. Myostatin expression was investigated in a set of 8 skeletal muscles, both at transcript and protein level, via Digital Droplet PCR and Western Blotting, respectively. No significant differences were observed at the transcript level, while, at the protein level, the only significant differences concerned the promyostatin dimer (75 kDa), in four pair-wise comparisons, all involving the tensor fasciae latae muscle. Beside the mentioned band at 75 kDa, additional bands were observed at around 40 and 25 kDa, corresponding to the promyostatin monomer and the active C-terminal myostatin dimer, respectively. Their weaker intensity suggests that the unprocessed myostatin dimers could act as important reservoirs of slowly available myostatin forms. Under this assumption, the sequential cleavage steps may contribute additional layers of control within an already complex regulatory framework.

Epidemiology and determinants of type 2 diabetes in south Asia

Type 2 diabetes has rapidly developed into a major public health problem in south Asia (defined here as Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka) in recent decades. During this period, major lifestyle changes associated with economic transition, industrialisation, urbanisation, and globalisation have been key determinants in the increasing burden of non-communicable diseases. A decline in nutrition quality, reduced physical activity, and increased sedentary behaviours are reflected in the increasing prevalence of type 2 diabetes and related risk factors in the region. The International Diabetes Federation 2017 estimates of the prevalence of diabetes in adults in the region range from 4·0% in Nepal to 8·8% in India. The prevalence of overweight ranges from 16·7% in Nepal to 26·1% in Sri Lanka, and the prevalence of obesity ranges from 2·9% in Nepal to 6·8% in Sri Lanka. An increasing proportion of children, adolescents, and women are overweight or obese, leading to a heightened risk of type 2 diabetes. Ethnic south Asians present with greater metabolic risk at lower levels of BMI compared with other ethnic groups (referred to as the south Asian phenotype), with type 2 diabetes often developing at a younger age, and with rapid progression of diabetic complications. Because of the presence of multiple risk factors and a body composition conducive to the development of type 2 diabetes, south Asians should be aggressively targeted for prevention. In this Series paper, we detail trends in the prevalence of diabetes in the region and address major determinants of the disease in the context of nutrition and physical activity transitions and the south Asian phenotype.

Body fat, metabolic syndrome and hyperglycemia in South Asians

The prevalence of overweight and obesity is escalating in South Asian countries. South Asians display higher total and abdominal obesity at a lower BMI when compared to Whites. Consequently, metabolic dysfunction leading to metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) will account for a majority of the health burden of these countries. In this review, we discuss those factors that contribute to MetS and T2DM in South Asians when compared to whites, focusing on adiposity. Abdominal obesity is the single-most important risk factor for MetS and its predisposition to T2DM. Excessive ectopic fat deposition in the liver (non-alcoholic fatty liver disease) has been linked to insulin resistance in Asian Indians, while the effects of ectopic fat accumulation in pancreas and skeletal muscle need more investigation. South Asians also have lower skeletal muscle mass than Whites, and this may contribute to their higher risk T2DM. Lifestyle factors contributing to MetS and T2DM in South Asians include inadequate physical activity and high intakes of refined carbohydrates and saturated fats. These are reflective of the recent but rapid economic transition and urbanization of the South Asian region. There is need to further the research into genetic determinants of dysmetabolism as well as gene x environment interactions. Collectively, MetS and T2DM have multi-factorial antecedents in South Asians and efforts to combat it through low-cost and socio-culturally appropriate lifestyle interventions need to be supported.

Genetics of obesity and its measures in India

Obesity is one of the largest global health problems associated with increased morbidity and mortality mediated by its association with several other metabolic disorders. The interaction between the genes and environment plays an important role in the manifestation of obesity. Despite a high heritability (40-70%) of obesity, the search for genetic variants associated with obesity susceptibility has been a challenging task. To date, limited studies have been conducted in India, restricted to the validation of few genetic variants identified by genomewide association studies. In this critical review, we sought to examine the current knowledge of genetic basis of obesity and its measures in the Indian population. A comprehensive literature search was performed using 'PubMed', 'Medline' and 'IndMed' databases to search for citations published until 31st May 2017, using the key terms as 'Genetics' AND 'obesity' AND 'India'. We identified 48 potential studies which fulfilled the eligibility criteria. The findings indicated that FTO, MC4R, TNF-α, PPAR-γ , UCP1, UCP2, LPL, LEPR, AMD1, IL6, APOE, ADIPOQ, DOK5, INSIG2, PBEF1, IL6R, Myostatin, CXCR4, HHEX, IRX3, POMC, NGN3, FOXA2, MTR, TCN and CHDH are some of the important genes studied among the Indian population. Importantly, the role of sexual dimorphism in the genetic regulation of obesity and body fat distribution was also reported in a few studies. Further, seven biological pathways have been identified that contribute to obesity pathogenesis in India. In conclusion, further exploration of pathway-based research on genetics of obesity can be useful for better understanding the pathophysiology of obesity in India.

South Asians: why are they at a higher risk for cardiovascular disease?

PURPOSE OF REVIEW

We comment on the high prevalence of cardiovascular disease (CVD) in South Asians (SA). The effect of various risk factors, for example biochemical, genetic, lifestyle, socioeconomic factors and psychosocial stress on CVD risk is discussed.

RECENT FINDINGS

'Prediabetes' is common in SA, but its relationship with coronary artery disease (CAD) is not significant unlike for the white population. At the same time, 'prediabetes' in SA is associated with an increased risk for cerebrovascular disease (CeVD). The differentiating factor could be the high lipids in Europeans and their relationship to CAD. Likewise, higher diastolic blood pressure in SA may explain the risk of CeVD. Small, dense, low-density lipoprotein (LDL), low high-density lipoprotein-cholesterol (HDL-C) concentration and high triglycerides may contribute to atherosclerosis. Thrombotic factors such as increased levels of plasminogen activator inhibitor, fibrinogen, lipoprotein (a) and homocysteine have been shown to be associated with increased CVD. Impaired cerebrovascular autoregulation and sympathovagal activity, increased arterial stiffness and endothelial dysfunction may increase CVD risk further. In addition, environmental and dietary factors may exaggerate the unfavourable cardiovascular profile through genetic factors.

SUMMARY

The implications of the findings suggest comprehensive screening of SA for CVD. Cultural differences should be considered while designing prevention strategies specifically targeting barriers for uptake of preventive service.

Structure of the human myostatin precursor and determinants of growth factor latency

Myostatin, a key regulator of muscle mass in vertebrates, is biosynthesised as a latent precursor in muscle and is activated by sequential proteolysis of the pro-domain. To investigate the molecular mechanism by which pro-myostatin remains latent, we have determined the structure of unprocessed pro-myostatin and analysed the properties of the protein in its different forms. Crystal structures and SAXS analyses show that pro-myostatin adopts an open, V-shaped structure with a domain-swapped arrangement. The pro-mature complex, after cleavage of the furin site, has significantly reduced activity compared with the mature growth factor and persists as a stable complex that is resistant to the natural antagonist follistatin. The latency appears to be conferred by a number of distinct features that collectively stabilise the interaction of the pro-domains with the mature growth factor, enabling a regulated stepwise activation process, distinct from the prototypical pro-TGF-β1. These results provide a basis for understanding the effect of missense mutations in pro-myostatin and pave the way for the design of novel myostatin inhibitors.

Vegetarian Diet and Cardiometabolic Risk among Asian Indians in the United States

Research studies have shown that plant-based diets confer cardiovascular and metabolic health benefits. Asian Indians (AIs) in the US (who have often followed plant-based diets) have elevated risk for chronic diseases such as diabetes, metabolic syndrome, and obesity suggesting ethnic vulnerability that imply genetic and/or lifestyle causative links. This study explored the association between this ethnic group and diabetes, obesity, and metabolic syndrome after controlling for demographics, acculturation, family history of diabetes, and lifestyle and clinical risk factors. The sample comprised of 1038 randomly selected adult AIs in seven US sites. Prevalence and metabolic syndrome was estimated, and obesity was calculated using the WHO Asian criteria. Multivariate analysis included multinomial logistic regression. The mean age and length of residency in the US were 47 and 18.5 years, respectively. The majority of respondents were vegetarians (62%) and educated. A vegetarian lifestyle was associated with females, food label users, respondents with poor/fair current health status, less acculturated, and those who reported their diet had not changed after coming to the US. Vegetarian status was a protective factor and lowered the risk for diabetes but not for metabolic syndrome and obesity in the regression model. Results provide a firm basis for educational programs.

Risk factors for low high-density lipoprotein among Asian Indians in the United States

AIM

To examine the differences in metabolic risk factors (RFs) by gender in the Asian Indian (AI) population in the United States.

METHODS

Using cross-sectional data from 1038 randomly selected Asian Indians, we investigated the relationship between metabolic syndrome (MetS) RFs, cardiovascular disease, and diabetes.

RESULTS

A greater percent of women in this group had increased waist circumference and low high density lipoprotein (HDL) levels than men, but AI males had increased blood glucose, increased blood pressure, and increased triglycerides compared to females. Those individuals who met the MetS criteria had increased cardiovascular disease. One of the biggest single RFs for cardiovascular disease and diabetes reported in the literature for AIs is low HDL.

CONCLUSION

Our results show that lack of knowledge about diabetes, low physical activity, increased body mass index, and age were the factors most significantly correlated with low HDL in this population. Future studies and prospective trials are needed to further elucidate causes of the MetS and diabetes in AIs.

Serum reference value of two potential doping candidates-myostatin and insulin-like growth factor-I in the healthy young male

Background

Myostatin negatively regulates muscle growth, and its inhibition by suitable proteins can increase muscle bulk and exercise performance. However, the reference values of serum myostatin in athletes performing strength training are still lacking.

Methods

A cross-sectional study recruiting28 male collegiate athletes performing strength training and 29 age-matched normal controls was conducted.

The serum concentration of myostatin and insulin-like growth factor 1 (IGF-1), grip strength, and body composition were the main outcome measures. We used regression models to analyze the correlation between serum markers and the physiological parameters. The athlete group had greater height, weight, body mass index (BMI), fat mass percentage, fat-free mass, muscle mass, waist girth, grip strength, and estimated daily energy expenditure.

Results

The IGF-1 concentration was higher in the athlete group (324 ± 80 vs. 263 ± 134 ng/ml), but the myostatin levels did not differ (12.1 ± 3.7 vs. 12.4 ± 3.5 ng/ml). The reference value for IGF-1 among the healthy young males was 293 ± 114 ng/ml, correlated with age and height; the value for myostatin was 12.3 ± 3.6 ng/ml, correlated negatively with BMI, fat mass percentage, and waist girth after adjustment for age.

Conclusion

Myostatin level is negatively related to fat percentage, and serum IGF-1 is positively related to height. The reference values could provide a basis for future doping-related study.

Biochemistry and Biology of GDF11 and Myostatin: Similarities, Differences, and Questions for Future Investigation

Growth differentiation factor 11 (GDF11) and myostatin (or GDF8) are closely related members of the transforming growth factor β superfamily and are often perceived to serve similar or overlapping roles. Yet, despite commonalities in protein sequence, receptor utilization and signaling, accumulating evidence suggests that these 2 ligands can have distinct functions in many situations. GDF11 is essential for mammalian development and has been suggested to regulate aging of multiple tissues, whereas myostatin is a well-described negative regulator of postnatal skeletal and cardiac muscle mass and modulates metabolic processes. In this review, we discuss the biochemical regulation of GDF11 and myostatin and their functions in the heart, skeletal muscle, and brain. We also highlight recent clinical findings with respect to a potential role for GDF11 and/or myostatin in humans with heart disease. Finally, we address key outstanding questions related to GDF11 and myostatin dynamics and signaling during development, growth, and aging.

Phenotype, Body Composition, and Prediction Equations (Indian Fatty Liver Index) for Non-Alcoholic Fatty Liver Disease in Non-Diabetic Asian Indians: A Case-Control Study

OBJECTIVE

In this study, we have attempted comparison of detailed body composition phenotype of Asian Indians with non-alcoholic fatty liver disease (NAFLD) vs. those without, in a case controlled manner. We also aim to analyse prediction equations for NAFLD for non-diabetic Asian Indians, and compare performance of these with published prediction equations researched from other populations.

METHODS

In this case-control study, 162 cases and 173 age-and sex-matched controls were recruited. Clinical, anthropometric, metabolic, and body composition profiles, and liver ultrasound were done. Fasting insulin levels, value of homeostasis model assessment of insulin resistance (HOMA-IR), and serum high sensitive C-reactive protein (hs-CRP) levels were evaluated. Multivariate logistic and linear regression analyses were used to arrive at prediction equations for fatty liver [Indian fatty liver index (IFLI)].

RESULTS

As compared to those without fatty liver, those with fatty liver exhibited the following; Excess dorsocervical fat ('Buffalo hump'), skin tags, xanthelasma, 'double chin', arcus; excess total, abdominal and subcutaneous adiposity, and high blood pressure, blood glucose, measures of insulin resistance (fasting insulin and HOMA-IR values), lipids and hs-CRP levels. Two prediction equations were developed; Clinical [Indian Fatty Liver Index-Clinical; IFLI-C]: 1(double chin) +15.5 (systolic blood pressure) +13.8 (buffalo hump); and IFLI-Clinical and Biochemical (CB): serum triglycerides+12 (insulin)+1(systolic blood pressure) +18 (buffalo hump). On ROC Curve analysis, IFLI performed better than all published prediction equations, except one.

CONCLUSION

Non-diabetic Asian Indians with NAFLD researched by us were overweight/obese, had excess abdominal and subcutaneous fat, multiple other phenotypic markers, had higher insulin resistance, glycemia, dyslipidemia and subclinical inflammation than those without. Prediction score developed by us for NAFLD; IFLI-C and IFLI-CB, should be useful for clinicians and researchers.

Low muscle mass is associated with metabolic syndrome only in nonobese young adults: the Korea National Health and Nutrition Examination Survey 2008-2010

Little is known about the relationship between body composition and metabolic risk factors in young adults. We hypothesized that low muscle mass (LMM) is associated with metabolic syndrome (MetS) and its components in young adults and that the associations vary by obesity. A cross-sectional analysis was conducted using the Korea National Health and Nutrition Examination Survey data. In total, 5300 young adults aged 19 to 39 years were evaluated. Low muscle mass was defined as an appendicular skeletal muscle mass/weight less than 1 SD below the mean for each participant's corresponding sex and age group. Obesity was defined as a body mass index greater than or equal to 25 kg/m2. The prevalence of LMM was higher in obese than nonobese participants (37.6% vs. 9.6%). In the nonobese participants, the prevalence of MetS, high waist circumference, high triglycerides, and high blood pressure was significantly greater in the LMM group than in the high muscle mass group. In the nonobese group, compared with high muscle mass participants, those with LMM had odds ratios for MetS of 3.6 (95% confidence interval, 1.48-8.76; P < .001) and 3.6 (95% confidence interval, 1.48-8.71; P < .001) in men and women, respectively, after adjusting for confounding factors. However, no significant association of LMM with MetS or its components was found in obese participants. In conclusion, our results suggest that young adults with LMM may have a high risk of MetS, especially when they are nonobese. Interventions aimed at increasing muscle mass at younger ages may have the potential to reduce MetS.

Frequency of the MSTN Lys(K)-153Arg(R) polymorphism among track & field athletes and swimmers

The myostatin (MSTN) Lys(K)-153Arg(R) polymorphism may influence skeletal muscle phenotypes. Carrying the rare R allele was associated with greater muscle mass.

PURPOSE

The aim of the present study was to assess the frequency of the MSTN Lys(K)-153Arg(R) polymorphism among Israeli track and field athletes (n=185) and swimmers (n=80).

METHODS

Track and field athletes were divided into long distance runners (major event 5000 m-marathon, n=113) and power athletes (major event 100200 m sprints and long jump, n=72). Swimmers were divided into long-distance swimmers (major event: 800-1500 m, n=38), and short-distance swimmers (major event: 50-100 m, n=42). The control group included 118 non-athletes healthy participants.

RESULTS

Twenty-seven track and field athletes (14.6%) and 7 swimmers (8.8%) were carriers of the rare MSTN R allele, and only two carried the 153RR genotype (0.8%). MSTN 153R allele frequency was significantly higher in top-compared to national-level among long-distance runners (26% versus 8%, p<0.05), short distance runners (16% versus 9%, p<0.05), and all runners combined (20% versus 8%, p<0.05), but not in top- compared to national-level swimmers. The frequency of arginine carriers was significantly greater among long compared to short-distance swimmers (16% versus 2%, p<0.03).

CONCLUSION

In contrast to elite endurance and power track and field athletes, the MSTN 153RR genotype was not found in short distance-swimmers, and among the long distance-swimmers it was not associated with top level swimming performance. Whether evaluation of the MSTN K153R polymorphism can be used for sports selection in young athletes needs to be further studied.

Myostatin Gene Polymorphism in an Elderly Sarcopenic Turkish Population

INTRODUCTION

One of the genetic contributors to sarcopenia predisposition is Myostatin (MSTN), which in humans encodes myostatin, a 376 amino acid growth factor protein that negatively regulates muscle growth. The aim of this study was to investigate MSTN polymorphisms in an elderly sarcopenic population in Turkey and determine how they relate to sarcopenia.

MATERIALS AND METHODS

The study included nursing home residents who were aged ≥65 years. Sarcopenia screening was performed using "The European Working Group on Sarcopenia in Older People" guidelines. Blood sample was taken from each participant and DNA was obtained from the peripheral blood. MSTN polymorphisms were genotyped by polymerase chain reaction and restriction fragment length polymorphism methods.

RESULTS

A total of 152 elderly patients were included in the study. The rate of sarcopenia was determined to be 41.4%. The DNA nucleotide sequence of all three MSTN exons was determined for each study participant. Among the 152 patients, only 6 (3.9%) showed an MSTN K153R heterozygous mutation. Among these, three participants were sarcopenic and three were nonsarcopenic. No statistically significant difference in the polymorphism frequency between the sarcopenic and control groups was observed (p=0.664).

CONCLUSIONS

MSTN genotyping revealed that only 3.9% (6/152) of participants had the MSTN K153R heterozygous mutation. Despite the detection of this mutation in the study group, no relationship was found between this mutation and sarcopenia.

The effect of myostatin on proliferation and lipid accumulation in 3T3-L1 preadipocytes

Myostatin is a critical negative regulator of skeletal muscle development, and has been reported to be involved in the progression of obesity and diabetes. In the present study, we explored the effects of myostatin on the proliferation and differentiation of 3T3-L1 preadipocytes by using 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyl tetrazolium bromide spectrophotometry, intracellular triglyceride (TG) assays, and real-time quantitative RT-PCR methods. The results indicated that recombinant myostatin significantly promoted the proliferation of 3T3-L1 preadipocytes and the expression of proliferation-related genes, including Cyclin B2, Cyclin D1, Cyclin E1, Pcna, and c-Myc, and IGF1 levels in the medium of 3T3-L1 were notably upregulated by 35.2, 30.5, 20.5, 33.4, 51.2, and 179% respectively (all P<0.01) in myostatin-treated 3T3-L1 cells. Meanwhile, the intracellular lipid content of myostatin-treated cells was notably reduced as compared with the non-treated cells. Additionally, the mRNA levels of Pparγ, Cebpα, Gpdh, Dgat, Acs1, Atgl, and Hsl were significantly downregulated by 22-76% in fully differentiated myostatin-treated adipocytes. Finally, myostatin regulated the mRNA levels and secretion of adipokines, including Adiponectin, Resistin, Visfatin, and plasminogen activator inhibitor-1 (PAI-1) in 3T3-L1 adipocytes (all P<0.001). Above all, myostatin promoted 3T3-L1 proliferation by increasing the expression of cell-proliferation-related genes and by stimulating IGF1 secretion. Myostatin inhibited 3T3-L1 adipocyte differentiation by suppressing Pparγ and Cebpα expression, which consequently deceased lipid accumulation in 3T3-L1 cells by inhibiting the expression of critical lipogenic enzymes and by promoting the expression of lipolytic enzymes. Finally, myostatin modulated the expression and secretion of adipokines in fully differentiated 3T3-L1 adipocytes.

High body fat and low muscle mass are associated with increased arterial stiffness in Asian Indians in North India

AIM

To investigate the associations of high body fat and low muscle mass with arterial stiffness in Asian Indians with type 2 diabetes mellitus (T2DM) in North India.

METHODS

In this cross sectional study, subjects with T2DM (males n=110, females n=58, mean age: 53.8±10.0years) were recruited. Anthropometry and body composition analysis were performed and measures of glycemia, lipids and PWV were analyzed.

RESULTS

Significant positive correlation was observed between PWV and body fat (p<0.05), left leg fat (p<0.05), and right leg fat (p<0.01) percentages only in females. In males, significant negative correlation was observed between PWV and truncal fat free mass (p<0.05) and fat free mass in right arm (p=0.05) and left arm (p<0.05). In both males and females, significant negative correlation was observed between PWV and fat free mass in left leg (p<0.01) and for right leg fat free mass only in females.

CONCLUSION

Excess adiposity and low fat free mass are associated with arterial stiffening in Asian Indians with T2DM in North India, with significant gender differences.

K153R polymorphism in myostatin gene increases the rate of promyostatin activation by furin

Recent studies demonstrated an association between the K153R polymorphism in the myostatin gene with extreme longevity, lower muscle strength and obesity but the molecular basis of these associations has not been clarified. Here, we show that the K153R mutation significantly increases the rate of proteolysis of promyostatin by furin, but has no effect on the activity of the latent complex or the cleavage of the latent complex by bone morphogenetic protein 1 (BMP-1). The increased rate of activation of K153R mutant promyostatin may explain why this polymorphism is associated with obesity, lower muscle strength and extension of lifespan.

Type 2 diabetes mellitus, metabolic syndrome, and mixed dyslipidemia: how similar, how different, and how to treat?

Individuals with mixed atherogenic dyslipidemia, type 2 diabetes mellitus (T2DM), and metabolic syndrome are at high risk of developing cardiovascular disease (CVD) and can often benefit greatly from preventive lifestyle and medical interventions. These conditions typically co-exist in an individual, and the lipid profiles associated with them have several features in common. The worldwide prevalence of T2DM, atherogenic dyslipidemia, and metabolic syndrome is increasing, particularly in southern Asia and the Middle East. Statins can lower low-density lipoprotein-cholesterol and reduce the risk of CVD in these high-risk individuals, but there is a residual risk of CVD associated with additional lipid abnormalities, such as high levels of triglycerides and low levels of high-density lipoprotein cholesterol. These abnormalities are commonly found in patients with T2DM and metabolic syndrome. Additional lipid-modifying therapies that target these abnormalities, such as fibrates and omega-3 polyunsaturated fatty acids, may be able to improve lipid profiles and further reduce the risk of CVD in these patients.

Diabetes in South Asians

Economic, dietary and other lifestyle transitions have been occurring rapidly in most South Asian countries, making their populations more vulnerable to developing Type 2 diabetes and cardiovascular diseases. Recent data show an increasing prevalence of Type 2 diabetes in urban areas as well as in semi-urban and rural areas, inclusive of people belonging to middle and low socio-economic strata. Prime determinants for Type 2 diabetes in South Asians include physical inactivity, imbalanced diets, abdominal obesity, excess hepatic fat and, possibly, adverse perinatal and early life nutrition and intra-country migration. It is reported that Type 2 diabetes affects South Asians a decade earlier and some complications, for example nephropathy, are more prevalent and progressive than in other races. Further, prevalence of pre-diabetes is high, and so is conversion to diabetes, while more than 50% of those who are affected remain undiagnosed. Attitudes, cultural differences and religious and social beliefs pose barriers in effective prevention and management of Type 2 diabetes in South Asians. Inadequate resources, insufficient healthcare budgets, lack of medical reimbursement and socio-economic factors contribute to the cost of diabetes management. The challenge is to develop new translational strategies, which are pragmatic, cost-effective and scalable and can be adopted by the South Asian countries with limited resources. The key areas that need focus are: generation of awareness, prioritizing health care for vulnerable subgroups (children, women, pregnant women and the underprivileged), screening of high-risk groups, maximum coverage of the population with essential medicines, and strengthening primary care. An effective national diabetes control programme in each South Asian country should be formulated, with these issues in mind.

Myostatin--the holy grail for muscle, bone, and fat?

Myostatin, a member of the transforming growth factor beta (TGF-β) superfamily, was first described in 1997. Since then, myostatin has gained growing attention because of the discovery that myostatin inhibition leads to muscle mass accrual. Myostatin not only plays a key role in muscle homeostasis, but also affects fat and bone. This review will focus on the impact of myostatin and its inhibition on muscle mass/function, adipose tissue and bone density/geometry in humans. Although existing data are sparse, myostatin inhibition leads to increased lean mass and 1 study found a decrease in fat mass and increase in bone formation. In addition, myostatin levels are increased in sarcopenia, cachexia and bed rest whereas they are increased after resistance training, suggesting physiological regulatory of myostatin. Increased myostatin levels have also been found in obesity and levels decrease after weight loss from caloric restriction. Knowledge on the relationship of myostatin with bone is largely based on animal data where elevated myostatin levels lead to decreased BMD and myostatin inhibition improved BMD. In summary, myostatin appears to be a key factor in the integrated physiology of muscle, fat, and bone. It is unclear whether myostatin directly affects fat and bone, or indirectly via muscle. Whether via direct or indirect effects, myostatin inhibition appears to increase muscle and bone mass and decrease fat tissue-a combination that truly appears to be a holy grail. However, at this time, human data for both efficacy and safety are extremely limited. Moreover, whether increased muscle mass also leads to improved function remains to be determined. Ultimately potential beneficial effects of myostatin inhibition will need to be determined based on hard outcomes such as falls and fractures.

Pathogenesis of type 2 diabetes in South Asians

The risk of developing type 2 diabetes mellitus (T2DM) is exceptionally high among both native and migrant South Asians. T2DM occurs more often and at a younger age and lower BMI, and the risk of coronary artery and cerebrovascular disease, and renal complications is higher for South Asians compared with people of White Caucasian descent. The high prevalence of T2DM and its related complications in South Asians, which comprise one-fifth of the total world's population, poses a major health and socioeconomic burden. The underlying cause of this excess risk, however, is still not completely understood. Therefore, gaining insight into the pathogenesis of T2DM in South Asians is of great importance. The predominant mechanism, in this ethnicity seems to be insulin resistance (IR) rather than an impaired β-cell function. In this systematic review, we describe several possible mechanisms that may underlie or contribute to the increased IR observed in South Asians.

Obesity and dyslipidemia in South Asians

Obesity and dyslipidemia are emerging as major public health challenges in South Asian countries. The prevalence of obesity is more in urban areas than rural, and women are more affected than men. Further, obesity in childhood and adolescents is rising rapidly. Obesity in South Asians has characteristic features: high prevalence of abdominal obesity, with more intra-abdominal and truncal subcutaneous adiposity than white Caucasians. In addition, there is greater accumulation of fat at “ectopic” sites, namely the liver and skeletal muscles. All these features lead to higher magnitude of insulin resistance, and its concomitant metabolic disorders (the metabolic syndrome) including atherogenic dyslipidemia. Because of the occurrence of type 2 diabetes, dyslipidemia and other cardiovascular morbidities at a lower range of body mass index (BMI) and waist circumference (WC), it is proposed that cut-offs for both measures of obesity should be lower (BMI 23–24.9 kg/m² for overweight and ≥25 kg/m² for obesity, WC ≥80 cm for women and ≥90 cm for men for abdominal obesity) for South Asians, and a consensus guideline for these revised measures has been developed for Asian Indians. Increasing obesity and dyslipidemia in South Asians is primarily driven by nutrition, lifestyle and demographic transitions, increasingly faulty diets and physical inactivity, in the background of genetic predisposition. Dietary guidelines for prevention of obesity and diabetes, and physical activity guidelines for Asian Indians are now available. Intervention programs with emphasis on improving knowledge, attitude and practices regarding healthy nutrition, physical activity and stress management need to be implemented. Evidence for successful intervention program for prevention of childhood obesity and for prevention of diabetes is available for Asian Indians, and could be applied to all South Asian countries with similar cultural and lifestyle profiles. Finally, more research on pathophysiology, guidelines for cut-offs, and culturally-specific lifestyle management of obesity, dyslipidemia and the metabolic syndrome are needed for South Asians.