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Cloning, expression and chromosome localization of porcine adiponectin and adiponectin receptors genes.

Adiponectin is a cytokine secreted specifically by adipocytes that has been proposed to enhance insulin sensitivity and prevent atherosclerosis. Adiponectin receptors (adipoR1 and adipoR2) are recently found in mice which act as receptors for globular and full-length adiponectin to mediate the fatty-acid oxidation and glucose uptake in muscle and liver. The primary goal of this study was to examine chromosome localization of porcine adiponectin and adiponectin receptors and the gene expression pattern in various tissues of pigs of the three genes. Radiation hybrid mapping demonstrated that porcine adiponectin, adipoR1 and adipoR2 were located to chromosome13q36-41, 10p11 and 5q25, in the regions that were syntenic to the homologs of human genes, respectively. Semi-quantitative RT-PCR showed that porcine adiponectin mRNA was specifically expressed in adipose tissue and porcine adipoR1 and adipoR2 mRNA were ubiquitously expressed in many tissues except brain. Comparison to adipoR2 mRNA which was highly expressed in liver, heart, kidney, adipose tissues and lung, adipoR1 mRNA was expressed at relatively high levels in porcine muscle, leukocytes and epididymis. Our data provide basic molecular information useful for the further investigation on the function of the three genes.

Adiponectin↗

Interaction of the -308G/A promoter polymorphism of the tumor necrosis factor-alpha gene with single-nucleotide polymorphism 45 of the adiponectin gene: effect on serum adiponectin concentrations in a Spanish population.

BACKGROUND: We investigated whether interactions of the -308G/A polymorphism in the promoter region of the tumor necrosis factor-alpha (TNF-alpha) gene with single-nucleotide polymorphisms (SNPs) 45 and 276 of the adiponectin gene are associated with circulating adiponectin and soluble TNF-alpha receptor 2 (sTNFR2) concentrations in a Spanish population. METHODS: We performed anthropometric and physiologic measurements in 809 unrelated participants recruited with a simple random sampling approach from respondents to a cross-sectional population-based epidemiologic survey in the province of Segovia in central Spain (Castille). RESULTS: The 2-h postload glucose and serum insulin concentrations were higher in -308A allele carriers than in -308G/G individuals homozygous for the TNF-alpha gene. Plasma concentrations of sTNFR2 were positively correlated with body mass index, waist-to-hip ratio, and sagittal abdominal diameter among individuals with type 2 diabetes. Individuals with type 2 diabetes and the -308A allele had higher sTNFR2 and lower adiponectin concentrations than -308G homozygotes. Moreover, individuals carrying both the TNF-alpha -308A allele and the G allele of SNP 45 in the adiponectin gene had the highest prevalence of impaired glucose tolerance (adjusted odds ratio, 1.26; 95% confidence interval, 1.01-1.56; P = 0.038) and had lower adiponectin concentrations (beta = -0.090; P = 0.005) than individuals without these genotypes. CONCLUSIONS: Our findings are the first to indicate that a higher incidence of impaired glucose tolerance and low circulating adiponectin concentration may be associated with interaction between the -308G/A promoter polymorphism of the TNF-alpha gene and SNP 45 in the adiponectin gene.

Abdomen↗

Insulin/Foxo1 pathway regulates expression levels of adiponectin receptors and adiponectin sensitivity.

Adiponectin/Acrp30 is a hormone secreted by adipocytes, which acts as an antidiabetic and antiatherogenic adipokine. We reported previously that AdipoR1 and -R2 serve as receptors for adiponectin and mediate increased fatty acid oxidation and glucose uptake by adiponectin. In the present study, we examined the expression levels and roles of AdipoR1/R2 in several physiological and pathophysiological states such as fasting/refeeding, obesity, and insulin resistance. Here we show that the expression of AdipoR1/R2 in insulin target organs, such as skeletal muscle and liver, is significantly increased in fasted mice and decreased in refed mice. Insulin deficiency induced by streptozotocin increased and insulin replenishment reduced the expression of AdipoR1/R2 in vivo. Thus, the expression of AdipoR1/R2 appears to be inversely correlated with plasma insulin levels in vivo. Interestingly, the incubation of hepatocytes or myocytes with insulin reduced the expression of AdipoR1/R2 via the phosphoinositide 3-kinase/Foxo1-dependent pathway in vitro. Moreover, the expressions of AdipoR1/R2 in ob/ob mice were significantly decreased in skeletal muscle and adipose tissue, which was correlated with decreased adiponectin binding to membrane fractions of skeletal muscle and decreased AMP kinase activation by adiponectin. This adiponectin resistance in turn may play a role in worsening insulin resistance in ob/ob mice. In conclusion, the expression of AdipoR1/R2 appears to be inversely regulated by insulin in physiological and pathophysiological states such as fasting/refeeding, insulin deficiency, and hyper-insulinemia models via the insulin/phosphoinositide 3-kinase/Foxo1 pathway and is correlated with adiponectin sensitivity.

Adenoviridae↗

Future adverse cardiac events can be predicted by persistently low plasma adiponectin concentrations in men and marked reductions of adiponectin in women after acute myocardial infarction.

There is conflicting information about whether mortality after AMI is higher in women than men. We investigated the significance of plasma adiponectin concentrations on major adverse cardiac events (MACE) after acute myocardial infarction (AMI) to delineate any differences between men and women. The study patients consisted of 114 men and 42 women with AMI. The incidence of MACE was significantly higher in women than men during the entire follow-up period (p<0.05). Compared with men for post-AMI MACE, the hazard ratio for women was 5.6 after adjustment for prognostic factors. Killip class (p<0.001) and sex differences (p<0.05) were independent predictors of MACE at 1 year post-AMI. Plasma adiponectin levels in women were significantly higher than men on admission (8.66 microg/mL [range: 6.6-14.08] versus 4.71 microg/mL [range: 3.47-7.27], p<0.0001) and during the post-AMI course (all p<0.0001). Multivariate analysis identified plasma adiponectin level on admission as an independent predictor of MACE in men (p<0.001) and the difference between plasma adiponectin levels at discharge and on admission in women (p<0.05). Patterns of serial changes in plasma adiponectin concentrations are different between men and women and plasma adiponectin concentrations can be used to predict future adverse cardiac events in AMI patients.

Acute Disease↗

An SNP in the adiponectin gene is associated with decreased serum adiponectin levels and risk for impaired glucose tolerance.

Adiponectin is a plasma protein produced by the adipose tissue. Hypoadiponectinemia has been associated with insulin resistance and several components of the metabolic syndrome (MS): type 2 diabetes, obesity, and dyslipidemia. We investigated whether single nucleotide polymorphisms (SNPs) at positions 45 and 276 in the adiponectin gene were associated with features of the MS in 747 unrelated Spanish subjects. The G allele of SNP45 and the G/G genotype of SNP276 were associated with impaired glucose tolerance (p = 0.020 and 0.042, respectively). The G/G genotype for SNP276 was associated with lower serum adiponectin levels as compared with the G/T and T/T genotypes (G/G, 10.10 +/- 0.24 microg/mL; G/T, 10.98 +/- 0.32 microg/mL; T/T, 12.00 +/- 0.92 microg/mL; p = 0.015) even after adjustment for sex, age, BMI, waist-to-hip ratio, homeostasis model assessment index, and the degree of glucose tolerance (p = 0.040). We found a significant negative association of circulating adiponectin levels with waist-to-hip ratio (r = -0.42, p < 0.001), sagittal abdominal diameter (r = -0.24, p < 0.001), triglycerides (r = -0.32, p < 0.001), homeostasis model assessment index (r = -0.14, p = 0.001), and uric acid (r = -0.36, p < 0.001) and positive association with high-density lipoprotein-cholesterol (r = 0.41, p < 0.001). Our findings indicate that serum adiponectin levels are associated with several components of the MS. The SNP276 of the adiponectin gene may affect impaired glucose tolerance and hypoadiponectinemia.

Adiponectin↗

Genetic variants of adiponectin receptor 2 are associated with increased adiponectin levels and decreased triglyceride/VLDL levels in patients with metabolic syndrome.

BACKGROUND: Adiponectin acts as an antidiabetic, antiinflammatory and antiatherogenic adipokine. These effects are assumed to be mediated by the recently discovered adiponectin receptors AdipoR1 and AdipoR2. AIM: The purpose of this study was to determine whether variations in the AdipoR1 and AdipoR2 genes may contribute to insulin resistance, dyslipidemia and inflammation. METHODS: We sequenced all seven coding exons of both genes in 20 unrelated German subjects with metabolic syndrome and tested genetic variants for association with glucose, lipid and inflammatory parameters. RESULTS: We identified three AdipoR2 variants (+795G/A, +870C/A and +963C/T) in perfect linkage disequilibrium (r2 = 1) with a minor allele frequency of 0.125. This haplotype was associated with higher plasma adiponectin levels and decreased fasting triglyceride, VLDL-triglyceride and VLDL-cholesterol levels. No association, however, was observed between the AdipoR2 SNP cluster and glucose metabolism. CONCLUSION: To our knowledge, this is the first study to identify an association between genetic variants of the adiponectin receptor genes and plasma adiponectin levels. Furthermore, our data suggest that AdipoR2 may play an important role in triglyceride/VLDL metabolism.

Adiponectin↗

Genome-wide linkage of plasma adiponectin reveals a major locus on chromosome 3q distinct from the adiponectin structural gene: the IRAS family study.

Adiponectin (APM1) is an adipocyte-derived peptide that contributes to glucose, lipid, and energy homeostasis. We assessed the genetic basis of plasma adiponectin in Hispanic-American and African-American families enrolled through the Insulin Resistance Atherosclerosis Study Family Study. A 10-cM genome scan was performed in two batches: an original set (set 1) consisting of 66 families (45 Hispanic American and 21 African American) and a replication set (set 2) consisting of 66 families (45 Hispanic American and 21 African American). Adiponectin levels were measured by radioimmunoassay in 1,727 individuals from 131 of 132 families. Linkage analysis was carried out in Hispanic Americans and African Americans separately in set 1, set 2, and the pooled set (set 1 plus set 2), with and without diabetic subjects. A major gene was mapped to 3q27 with a logarithm of odds (LOD) score of 8.21 in the Hispanic-American sample. Ninety-six unrelated individuals were screened for polymorphisms in the APM1 gene, and 18 single nucleotide polymorphisms (SNPs) were genotyped in the Hispanic-American sample. Plasma adiponectin level was modestly associated with two SNPs and their accompaning haplotypes. Incorporating each or both SNPs in the linkage analysis, however, did not significantly reduce the LOD score. Therefore, a quantitative trait locus at 3q27, likely distinct from the APM1 gene, contributes to the variation of plasma adiponectin levels in the Hispanic-American population.

Adiponectin↗

Adiponectin genetic variability, plasma adiponectin, and cardiovascular risk in patients with type 2 diabetes.

Adiponectin is an adipocyte-derived hormone that has shown anti-inflammatory and antiatherogenic effects. We assessed the associations of variants in the adiponectin gene (ADIPOQ) with circulating adiponectin levels and cardiovascular risk among women with type 2 diabetes. Of 989 diabetic women from the Nurses' Health Study, 285 developed cardiovascular disease (CVD) during follow-up through 2000. We genotyped five ADIPOQ polymorphisms in the CVD case and control subjects. A promoter polymorphism -11365C-->G was significantly associated with lower plasma adiponectin levels (P = 0.004). The homozygotes of allele -4034C were significantly associated with approximately 60% increased cardiovascular risk (odds ratio 1.62 [95% CI 1.07-2.45]). Adjustment for age, BMI, and other covariates did not appreciably change the associations. In addition, a common haplotype possessing allele +276T (CAATT) was associated with a significantly lower CVD risk than the most common haplotype (CAATG) (0.70 [0.50-0.98]). In our meta-analysis of 827 CVD case and 1,887 CVD-free control subjects, polymorphism +276G-->T was significantly associated with approximately 45% (20-62%) decreased CVD risk under a recessive inheritance mode in diabetic patients. In conclusion, ADIPOQ promoter polymorphism -11365C-->G was associated with plasma adiponectin levels, whereas polymorphisms -4034A-->C and +276G-->T were associated with CVD risk in diabetic patients.

Adiponectin↗

Differential regulation of adiponectin receptor gene expression by adiponectin and leptin in myotubes derived from obese and diabetic individuals.

OBJECTIVE: This study aimed to investigate the regulation of adiponectin receptors 1 (AdipoR1) and 2 (AdipoR2) gene expression in primary skeletal muscle myotubes, derived from human donors, after exposure to globular adiponectin (gAd) and leptin. RESEARCH METHODS AND PROCEDURES: Four distinct primary cell culture groups were established [Lean, Obese, Diabetic, Weight Loss (Wt Loss); n = 7 in each] from rectus abdominus muscle biopsies obtained from surgical patients. Differentiated myotube cultures were exposed to gAd (0.1 microg/mL) or leptin (2.5 microg/mL) for 6 hours. AdipoR1 and AdipoR2 gene expression was measured by real-time polymerase chain reaction analysis. RESULTS: AdipoR1 mRNA expression in skeletal muscle myotubes derived from Lean subjects (p < 0.05) was stimulated 1.8-fold and 2.5-fold with gAd and leptin, respectively. No increase in AdipoR1 gene expression was measured in myotubes derived from Obese, Diabetic, or Wt Loss subjects. AdipoR2 mRNA expression was unaltered after gAd and leptin exposure in all myotube groups. DISCUSSION: Adiponectin and leptin are rapid and potent stimulators of AdipoR1 in myotubes derived from lean healthy individuals. This effect was abolished in myotubes derived from obese, obese diabetic subjects, and obese-prone individuals who had lost significant weight after bariatric surgery. The incapacity of skeletal muscle of obese and diabetic individuals to respond to exogenous adiponectin and leptin may be further suppressed as a result of impaired regulation of the AdipoR1 gene.

Adiponectin↗

The SNP276G>T polymorphism in the adiponectin (ACDC) gene is more strongly associated with insulin resistance and cardiovascular disease risk than SNP45T>G in nonobese/nondiabetic Korean men independent of abdominal adiposity and circulating plasma adiponectin.

This study aimed to determine whether polymorphisms of the adiponectin (ACDC) gene independently contribute to insulin resistance (IR) and other cardiovascular disease (CVD) risk factors in nonobese, nondiabetic Korean men after adjusting for major environmental factors that influence IR. Among the 7 ACDC single-nucleotide polymorphisms (SNPs;C-11377G, T45G, G276T, H241P, Y111H, G90S, and R221S) prescreened in 48 subjects, we genotyped 333 subjects for SNP45 and SNP276, both of which showed an allele frequency of more than 2%. In Pearson correlation and multiple stepwise regression analyses, we found that waist circumference was the most important influencing factor (beta = .369, P < .001) in homeostasis model assessment (HOMA)-IR, whereas plasma adiponectin was the second most important (beta = -.217, P = .023). At position 276, T/T subjects showed significantly lower glucose concentrations (P = .043) and higher low-density lipoprotein particle sizes (P = .033) than the G/G and G/T subjects. The subjects also had lower serum triglycerides and HOMA-IR; however, these results were not statistically significant. After adjusting for waist circumference and plasma adiponectin, T/T subjects showed a significantly lower HOMA-IR than G/G or G/T subjects (P = .048). On the other hand, at position 45, only glucose concentrations were significantly lower in G carriers (P = .005). In the SNP45-SNP276 haplotype test, TT/TT subjects (having T/T at both SNP45 and SNP276) showed significantly lower IR before and after adjusting for waist circumference and adiponectin levels than did other carriers. In conclusion, we suggest that SNP276G>T, rather than SNP45T>G, is more strongly associated (both directly and indirectly) than with several components of metabolic syndrome and CVD risk, including IR, triglyceride concentration, and low-density lipoprotein particle size, in nonobese, nondiabetic men.

Abdomen↗

Osmotin is a homolog of mammalian adiponectin and controls apoptosis in yeast through a homolog of mammalian adiponectin receptor.

The antifungal activity of the PR-5 family of plant defense proteins has been suspected to involve specific plasma membrane component(s) of the fungal target. Osmotin is a tobacco PR-5 family protein that induces apoptosis in the yeast Saccharomyces cerevisiae. We show here that the protein encoded by ORE20/PHO36 (YOL002c), a seven transmembrane domain receptor-like polypeptide that regulates lipid and phosphate metabolism, is an osmotin binding plasma membrane protein that is required for full sensitivity to osmotin. PHO36 functions upstream of RAS2 in the osmotin-induced apoptotic pathway. The mammalian homolog of PHO36 is a receptor for the hormone adiponectin and regulates cellular lipid and sugar metabolism. Osmotin and adiponectin, the corresponding "receptor" binding proteins, do not share sequence similarity. However, the beta barrel domain of both proteins can be overlapped, and osmotin, like adiponectin, activates AMP kinase in C2C12 myocytes via adiponectin receptors.

Adiponectin↗

Impact of adiponectin gene polymorphisms on plasma lipoprotein and adiponectin concentrations of viscerally obese men.

The aim of this study was first to examine the relationships between adiponectin gene (Apm1) polymorphisms and anthropometric indices as well as plasma adiponectin and lipoprotein/lipid levels, and then to investigate whether the presence of visceral obesity or insulin resistance may modulate the impact of these polymorphisms on metabolic risk variables. Molecular screening of the Apm1 gene was achieved, and a sample of 270 unrelated men recruited from the greater Quebec City area and selected to cover a wide range of body fatness values was genotyped. Sequencing of the Apm1 gene revealed two previously reported polymorphisms (c.45T>G and c.276G>T) as well as two newly identified genetic variations (-13752delT and -13702G>C). Carriers of the c.276T allele had higher LDL-cholesterol and lower HDL-triglyceride concentrations than did 276G/G homozygotes (P=0.02 and P=0.01, respectively). Carriers of the c.45G allele exhibited higher plasma adiponectin concentrations than did 45T/T homozygotes (P=0.04). After dividing each genotype group into subgroups for visceral AT, homozygotes for the normal allele at position -13752delT, carriers of the c.45G allele, and carriers of the c.276T allele had similar total apolipoprotein B (apoB) concentrations, whether they were viscerally obese or not. These results suggest that some Apm1 gene polymorphisms influence plasma adiponectin concentrations and lipoprotein/lipid levels. In addition, the impact of these polymorphisms is modulated by the presence of visceral obesity.

Adiponectin↗

Genetic variation in adiponectin receptor 1 and adiponectin receptor 2 is associated with type 2 diabetes in the Old Order Amish.

Adiponectin receptor 1 (ADIPOR1) and adiponectin receptor 2 (ADIPOR2) are newly identified receptors for adiponectin, an adipocytokine with anti-inflammatory and insulin-sensitizing properties. We screened for polymorphisms by performing sequence analysis on all eight exons, splice junctions, and approximately 2 kb of the 5' flanking regions of each receptor. We detected 5 single nucleotide polymorphisms (SNPs) in ADIPOR1 and 16 SNPs in ADIPOR2. We genotyped these SNPs in Amish subjects with type 2 diabetes (n = 137), impaired glucose tolerance (IGT) (n = 139), and normal glucose tolerance (n = 342) to test for association with type 2 diabetes. Three intronic SNPs in ADIPOR1 were significantly associated with type 2 diabetes (P = 0.014-0.007; odds ratio [OR] 1.61-1.65) and in high linkage disequilibrium (r2 = 0.97-1.0). In ADIPOR2, we found that five SNPs delineated one large haplotype block (r2= 0.9-1.0) spanning >98 kb of the gene and promoter region, which was strongly associated with the combined type 2 diabetes/IGT trait (P < or = 0.001; OR 1.64-1.71). To our knowledge, these data provide the first evidence for association between variation in the adiponectin receptors and type 2 diabetes.

Aged↗

Adiponectin and adiponectin receptor gene variants in relation to resting metabolic rate, respiratory quotient, and adiposity-related phenotypes in the Quebec Family Study.

BACKGROUND: Despite adiponectin's presumed role in fatty acid oxidation and energy homeostasis, little is known about the effect of gene variants on substrate oxidation, energy expenditure, and adiposity-related phenotypes. OBJECTIVE: We examined the effects of genetic variation in adiponectin (ADIPOQ) and adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2) on resting metabolic rate, respiratory quotient (RQ), and adiposity-related phenotypes. DESIGN: We studied the associations of ADIPOQ, ADIPOR1, and ADIPOR2 polymorphisms with resting metabolic rate, RQ, and body mass index, percentage body fat, sum of 6 skinfold thicknesses, waist circumference, and total, subcutaneous, and visceral fat in 759 participants in the Québec Family Study. RESULTS: The ADIPOQ 45T-->G single-nucleotide polymorphism (SNP) was significantly (P = 0.0002 to 0.04) associated with overall adiposity and abdominal adiposity; the rare homozygotes (G/G) had a leaner phenotype than did the carriers of the common allele. One SNP each in the putative promoter of ADIPOR1 (ie, -3882T-->C) and ADIPOR2 (ie, IVS1 -1352G-->A) was associated with RQ (P = 0.03 and 0.04, respectively), and the association was even stronger in nonobese persons (P = 0.02 and 0.003). Carriers of the common alleles (ADIPOR1 T and ADIPOR2 G alleles) had a lower RQ than did the rare homozygotes. A significant genotype-by-genotype interaction (P = 0.0002 to 0.02) was found between SNPs in the promoters of ADIPOQ (-3971A-->G) and ADIPOR1 (-3882T-->C). Subjects carrying the minor ADIPOQ allele (G allele) who were rare homozygotes (C/C) for the ADIPOR1 SNP had a higher RQ (P = 0.003) and greater overall (P < 0.03) and abdominal (P < 0.05) adiposity than did persons with other genotype combinations. CONCLUSIONS: Previous findings that the ADIPOQ 45T-->G variant contributes to overall fatness and abdominal obesity are confirmed. Moreover, variants in the promoter region of both ADIPOR genes contribute to substrate oxidation.

Adiponectin↗

Hyperglycemia- and hyperinsulinemia-induced alteration of adiponectin receptor expression and adiponectin effects in L6 myoblasts.

Adiponectin has been shown to regulate glucose and fatty acid uptake and metabolism in skeletal muscle. Here we investigated the role of the recently cloned adiponectin receptor (AdipoR) isoforms in mediating effects of both globular (gAd) and full-length (fAd) adiponectin, and their regulation by hyperglycemia (25 mM, 20 h) and hyperinsulinemia (100 nM, 20 h). We used L6 rat skeletal muscle cells, which were found to express both AdipoR1 and AdipoR2 mRNA in a ratio of over 6:1 respectively. Hyperglycemia and hyperinsulinemia both decreased AdipoR1 receptor expression by approximately 50%, while the latter induced an increase of approximately threefold in AdipoR2 expression. The ability of gAd to increase GLUT4 myc translocation, glucose uptake, fatty acid uptake and oxidation, as well as AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation, was decreased by both hyperglycemia and hyperinsulinemia. Interestingly, hyperinsulinemia induced the ability of fAd to elicit fatty acid uptake and enhanced fatty acid oxidation in response to fAd. In summary, our results suggest that both hyperglycemia and hyperinsulinemia cause gAd resistance in rat skeletal muscle cells. However, hyperinsulinemia induces a switch toward increased fAd sensitivity in these cells.

AMP-Activated Protein Kinases↗

A polymorphism in the adiponectin gene influences adiponectin expression levels in visceral fat in obese subjects.

OBJECTIVE: Reduced serum adiponectin levels have been found in obesity and type 2 diabetes and variations in the adiponectin gene (APM1) have been associated with type 2 diabetes and features of the metabolic syndrome in different populations. STUDY DESIGN: Here, we investigated the expression of APM1 in adipose tissue and studied the relationship between variation in APM1 expression, the APM1 G276T polymorphism, the common PPARG Pro12Ala polymorphism and clinical features of 36 morbidly obese (body mass index (BMI) 41.5 +/- 4.9 kg/m2) nondiabetic subjects. RESULTS: APM1 mRNA expression in visceral fat was correlated with serum adiponectin levels (r = 0.54, P = 0.012). In visceral, but not in subcutaneous, adipose tissue APM1 mRNA level was 38% higher among carriers of the APM1 G276T T allele (G/T and T/T) than among carriers of the G/G genotype (0.91 +/- 0.06 for G/T and T/T carriers vs 0.66 +/- 0.09 for G/G carriers, P = 0.013). Carriers of the T allele also had significantly higher body fat percent compared to G/G carriers (65 +/- 6 vs 56 +/- 10%, P = 0.011). CONCLUSION: Our results indicate that genetic variation in APM1 influences the expression of the gene in visceral adipose tissue and suggest a potential role for such variation in regulation of body fat accumulation in obese subjects.

Adiponectin↗

Changes in expression levels of genes involved in fatty acid metabolism: upregulation of all three members of the PPAR family (alpha, gamma, delta) and the newly described adiponectin receptor 2, but not adiponectin receptor 1 during neonatal cardiac development of the rat.

UNLABELLED: During neonatal cardiac development, the heart changes its substrate preference from glucose to fatty acids. The aim of this study was to investigate the changes in mRNA expression levels of genes involved in the control of cardiac fatty acid metabolism in the transition from neonatal to adult life. METHODS: mRNA expression levels for peroxisome proliferator activated receptor (PPAR) alpha, gamma and delta, PPARgamma co-factor 1 alpha and beta (PGC-1 alpha and beta), 9-cis retinoc-acid-activated receptor alpha, beta and gamma (RXR alpha, beta, gamma), 5'-AMP activated protein kinase (AMPK) alpha1 and alpha2, adiponectin receptor 1 and 2 (AR 1 and AR 2) were measured in heart tissue of neonatal 0-day, 7-day and 21- day old rats. RESULTS: mRNA expression of all three members of the PPAR family were upregulated significantly from day 0 to day 21 (alpha +117%, gamma +133%, delta +203%). In addition, m-RNA expression of all RXR isoforms increased from day 0 to day 7 (alpha +125%, beta +69%; gamma +41%). AR 2 exhibited a small but significant increase in mRNA expression (+ 46%). CONCLUSIONS: We were able to demonstrate for the first time that in addition to PPARalpha, also PPARgamma and delta, as well as all RXR isoforms and AR 2 are upregulated in the heart during neonatal development.

Animals↗

Increased plasma adiponectin concentrations in poorly controlled patients with phenylketonuria normalize with a strict diet: evidence for catecholamine-mediated adiponectin regulation and a complex effect of phenylketonuria diet on atherogenesis risk factors.

Adiponectin (Adpn), an adipose tissue-derived hormone, prevents endothelial inflammation and early atherogenesis. Classic phenylketonuria (PKU), an inborn error of phenylalanine (Phe) metabolism, results in a reduction of catecholamine biosynthesis and requires treatment with lifelong low-Phe diet to prevent mental dysfunction and allow proper intellectual development. In this study, we evaluated the effect of the quality of PKU diet on plasma Adpn concentrations and related biochemical indices of endothelial dysfunction and atherogenesis. Patients with PKU were divided into groups A (n = 18), who were on a strict diet, and B (n = 18), who were on a loose diet, after evaluation of their 30-day dietetic diaries and measurement of Phe blood concentrations. Twenty healthy children of similar ages and body mass indexes served as controls (group C). Group A patients had normal circulating catecholamines and Adpn and decreased tumor necrosis factor alpha concentrations and low-density lipoprotein cholesterol/apolipoprotein B ratio compared with groups B and C. Despite these favorable parameters, however, homocysteine concentration was twice as high in group A compared with groups B and C. Interestingly, group B patients under loose dietary control had significantly elevated Adpn concentrations compared with groups A and C and increased tumor necrosis factor alpha and an unfavorable lipid profile, but normal levels of homocysteine. These data support the hypothesis that catecholamines inhibit Adpn secretion and that the elevated Adpn of the poorly controlled patients might moderate their risk for endothelial dysfunction and atherogenesis. Homocysteine production appears to be unfavorably affected by a strict PKU diet, diverging from the rest of the atherogenesis risk factors, which were improved in the well-controlled patients.

Adiponectin↗