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Biomedical subjects

Leif Groop

Publications and source records attributed to Leif Groop.

At least 55 records · Page 3Linked to original sources
PubMed2003

A genome wide scan for early onset primary hypertension in Scandinavians.

With the aim of identifying hypertension susceptibility loci, we performed a genome wide scan in Scandinavian sib-pairs with early onset primary hypertension. To be classified as affected, a diagnosis of primary hypertension at age </=50 years was required. Two hundred and forty three patients with onset of primary hypertension at 40.0+/-7.7 (mean+/-SD) years from 91 families (91 sib-ships with a mean of 2.7 and a range of 2-6 affected members per sib-ship) were genotyped with 362 microsatellite markers with a density of approximately 10 cM. Loci obtaining nominal P</=0.016 (LOD score >/= 1.0) were fine mapped with additional markers. Multipoint non-parametric linkage analysis was performed using GENEHUNTER v 2.0. Using simulations, a nominal P</=0.0002 was determined to be a genome wide significant evidence of linkage. In the 10 cM genome wide scan, nominal P</=0.016 were found on chromosomes 1 at 81 cM (P=0.007), 2 at 115 cM (P=0.006), 3 at 108 cM (P=0.006), 14 at 45 cM (P=0.0002) and at 99 cM (P=0.001), 17 at 42 cM (P=0.015) and 19 at 89 cM (P=0.007). After fine mapping of these loci, one of the chromosome 14 loci just obtained the level of genome wide significance (P=0.0002 at 41 cM) and the chromosome 2 locus reached suggestive evidence of linkage (P=0.002 at 118 cM). Our data suggest a hypertension susceptibility locus on chromosome 14 around 41 cM. The locus on chromosome 2 is also promising as it has been implicated in hypertension and blood pressure regulation in earlier genome scans.

Adult↗
PubMed2003

No evidence of a relation between 11beta-hydroxysteroid dehydrogenase type 2 activity and salt sensitivity.

BACKGROUND: The ratio of urinary concentrations of tetrahydrocortisol plus allotetrahydrocortisol to tetrahydrocortisone [(THF + ATHF)/THE] reflects the activity of the enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11BHSD2), which converts cortisol to cortisone in the kidney and thereby protects the mineralocorticoid receptor from the mineralocorticoid action of cortisol. The aim of the present study was to investigate whether 11BHSD2 activity is affected by salt intake and if it is related to salt sensitivity. METHODS: Concentrations of THF, ATHF, and THE in 24-h urine collections was determined by gas chromatography at baseline, after 1 week on a low salt diet (10 mmol/d), and after another week on a high salt diet (240 mmol/d) in 29 healthy subjects with heredity for hypertension. Salt sensitivity was defined as the difference between mean arterial blood pressure (BP) after the high salt diet and mean arterial BP after the low salt diet. RESULTS: The high salt diet increased (THF + ATHF)/THE by 5.1% +/- 9.4% (P =.009) when compared to the low salt diet. The salt-induced change of (THF + ATHF)/THE was not related to salt sensitivity. There was no correlation between salt sensitivity and (THF + ATHF)/THE at baseline (r = -0.18, P =.34), whereas salt sensitivity was inversely related to (THF + ATHF)/THE after the low (r = -0.38, P =.05) and after the high (r = -0.39, P =.04) salt diets. CONCLUSIONS: We found no support for an association between enhanced salt sensitivity and reduced 11BHSD2 activity.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2003

Fat feeding impairs glycogen synthase activity in mice without effects on its gene expression.

To examine whether the effects of high-fat feeding on glycogen synthase (GS) activity and mRNA levels differ between diabetes-prone (C57BL/6J) and diabetes-resistant mice (NMRI), we measured GS activity and mRNA levels in muscle from C57BL/6J and NMRI mice fed a high-fat or normal chow diet for 3, 6, and 15 months. As compared with chow feeding, fat feeding increased plasma insulin levels in C57BL/6J mice at 15 months (464 +/- 29 v 267 +/- 47 pmol/L, P =.005), which was associated with elevated plasma glucose levels at 15 months (5.3 +/- 0.3 v 3.8 +/- 0.2 mmol/L, P =.001). Fat feeding increased plasma insulin levels also in NMRI mice at 15 months (705 +/- 145 v 275 +/- 64 pmol/L, P =.01) without, however, a rise of plasma glucose levels. In parallel with increased insulin levels, decreased muscle GS fractional velocity (FV) was observed at 6 (49.0% +/- 2.6% v 69.1% +/- 7.3%, P =.04) and 15 (45.8% +/- 1.8% v 53.4% +/- 1.6 %, P <.01) months but not at 3 months in the fat-fed C57BL/6J mice. Similarly, there was a significant decrease in GS fractional activity at 3 (57.9% +/- 4.3% v 70.4% +/- 2.6 %, P <.03) and 15 (47.3% +/- 2.4% v 56.4% +/- 2.1%, P =.02) but not at 6 months in the fat-fed NMRI mice. The decrease in GS activity was not associated with changes in mRNA levels at any time points. We conclude that (1) fat feeding results in similar elevation of plasma insulin levels and impairs GS activity in C57BL/6J and NMRI mice, and (2) the changes in GS activity do not involve effects on gene expression.

Animals↗
PubMed2003

Dietary intakes and plasma concentrations of carotenoids and tocopherols in relation to glucose metabolism in subjects at high risk of type 2 diabetes: the Botnia Dietary Study.

BACKGROUND: The role of antioxidants in the pathogenesis of type 2 diabetes is uncertain. OBJECTIVE: We evaluated cross-sectional relations of dietary intakes and plasma concentrations of antioxidants with glucose metabolism in a high-risk population. DESIGN: The subjects were 81 male and 101 female first- and second-degree, nondiabetic relatives of patients with type 2 diabetes. Antioxidant intake data were based on 3-d food records. Subjects taking supplements containing beta-carotene or alpha-tocopherol were excluded. Plasma antioxidant concentrations were measured by HPLC. By using multiple linear regression analysis and adjusting for demographic, anthropometric, and lifestyle covariates, we studied whether dietary and plasma alpha- and beta-carotene, lycopene, and alpha- and gamma-tocopherol were related to fasting and 2-h concentrations of glucose and nonesterified fatty acids during an oral-glucose-tolerance test, to the homeostasis model assessment index of insulin resistance, and to measures of beta cell function (incremental 30-min serum insulin concentration during an oral-glucose-tolerance test and first-phase insulin secretion during an intravenous-glucose-tolerance test). RESULTS: In men, dietary carotenoids were inversely associated with fasting plasma glucose concentrations (P < 0.05), plasma beta-carotene concentrations were inversely associated with insulin resistance (P = 0.003), and dietary lycopene was directly related to baseline serum concentrations of nonesterified fatty acids (P = 0.034). In women, dietary alpha-tocopherol and plasma beta-carotene concentrations were inversely and directly associated, respectively, with fasting plasma glucose concentrations (P < 0.05). In both sexes, cholesterol-adjusted alpha-tocopherol concentrations were directly associated with 2-h plasma glucose concentrations (P < 0.05). CONCLUSION: The data suggest an advantageous association of carotenoids, which are markers of fruit and vegetable intake, with glucose metabolism in men at high risk of type 2 diabetes.

Adult↗
PubMed2003

Peroxisome proliferator-activated receptor-gammaPro12Ala polymorphism and the association with blood pressure in type 2 diabetes: skaraborg hypertension and diabetes project.

OBJECTIVE: This study explored whether the Pro12Ala polymorphism in the peroxisome proliferator-activated receptor-gamma (PPARgamma) is associated with blood pressure in subjects with type 2 diabetes. DESIGN: A community-based, cross-sectional observation study. SETTING: Primary care. PATIENTS: One hundred and ninety-two men and 192 women with type 2 diabetes who consecutively underwent annual follow-up. MAIN OUTCOME MEASURE: The PPARgammaPro12Ala genotype was determined by polymerase chain reaction-based techniques. Associations between genotype and blood pressure were analysed by linear regression and expressed as differences in blood pressure (delta) with 95% confidence interval (CI). RESULTS: The mean systolic blood pressure and the diastolic blood pressure were 160 mmHg (standard deviation = 22.8) and 84 mmHg (standard deviation = 9.6), respectively. Subjects with Pro/Ala (24%) or Ala/Ala (2%) had lower diastolic blood pressure (delta = 2.8; 95% CI, 0.6-5.0) when adjusted for age and gender compared with Pro/Pro subjects (74%). This association was restricted to men (delta = 4.4; 95% CI, 1.3-7.4), who also had a borderline significant difference in systolic blood pressure (delta = 6.9; 95% CI, -0.8 to 13.8). In men the difference in diastolic blood pressure remained after adjustment for age, body mass index, serum triglycerides, serum insulin and haemoglobin A(1c) (delta = 4.6; 95% CI, 1.1-8.1). A subanalysis of normotensive men (n = 100) confirmed the difference associated with the Pro12Ala polymorphism in diastolic blood pressure (delta = 5.2; 95% CI, 0.6-10.0). CONCLUSIONS: The common Pro12Ala polymorphism in PPARgamma is associated with lower diastolic blood pressure in male subjects with type 2 diabetes.

Aged↗
PubMed2003

The SLC6A14 gene shows evidence of association with obesity.

In our previous genome-wide scan of Finnish nuclear families, obesity was linked to chromosome Xq24. Here we analyzed this 15-Mb region by genotyping 9 microsatellite markers and 36 single nucleotide polymorphisms (SNPs) for 11 positional and functional candidate genes in an extended sample of 218 obese Finnish sibling pairs (sibpairs) (BMI > 30 kg/m2). Evidence of linkage emerged mainly from the obese male sibpairs, suggesting a gender-specific effect for the underlying gene. By constructing haplotypes among the obese male sibpairs, we restricted the region from 15 Mb to 4 Mb, between markers DXS8088 and DXS8067. Regional functional candidate genes were tested for association in an initial sample of 117 cases and 182 controls. Significant evidence was observed for association for an SNP in the 3'-untranslated region of the solute carrier family 6 member 14 (SLC6A14) gene (P = 0.0002) and for SNP haplotypes of the SLC6A14 gene (P = 0.0007-0.006). Furthermore, an independent replication study sample of 837 cases and 968 controls from Finland and Sweden also showed significant differences in allele frequencies between obese and non-obese individuals (P = 0.003). The SLC6A14 gene is an interesting novel candidate for obesity because it encodes an amino acid transporter, which potentially regulates tryptophan availability for serotonin synthesis and thus possibly affects appetite control.

Adult↗
PubMed2003

A combination of human leukocyte antigen DQB1*02 and the tumor necrosis factor alpha promoter G308A polymorphism predisposes to an insulin-deficient phenotype in patients with type 2 diabetes.

Our previous results have suggested that genes outside the human leukocyte antigen (HLA) class II locus may affect the phenotype of type 2 diabetic patients from families with both type 1 and type 2 diabetes (mixed type 1/2). To study whether the TNF alpha gene could be such a modifying gene, we studied TNF alpha promoter polymorphisms (G-->A substitution at positions -308 and -238) in relation to HLA-DQB1 genotypes in type 2 patients from mixed type 1/2 families or common type 2 diabetes families as well as in patients with adult-onset type 1 diabetes and control subjects. The TNF alpha(308) AA/AG genotype frequency was increased in adult onset type 1 patients (55%, 69 of 126), but it was similar in type 2 patients from type 1/2 families (35%, 33/93) or common type 2 families (31%, 122 of 395), compared with controls (33%, 95/284; P < 0.0001 vs. type 1). The TNF alpha(308) A and DQB1*02 alleles were in linkage disequilibrium in type 1 patients (Ds = 0.81; P < 0.001 vs. Ds = 0.25 in controls) and type 2 patients from type 1/2 families (Ds = 0.59, P < 0.05 vs. controls) but not in common type 2 patients (Ds = 0.39). The polymorphism was associated with an insulin-deficient phenotype in the type 2 patients from type 1/2 families only together with DQB*02, whereas the common type 2 patients with AA/AG had lower waist to hip ratio [0.92 (0.12) vs. 0.94 (0.11), P = 0.008] and lower fasting C-peptide concentration [0.48 (0.47) vs. 0.62 (0.46) nmol/liter, P = 0.020] than those with GG, independently of the presence of DQB1*02. In conclusion, TNF alpha is unlikely to be the second gene in the HLA area responsible for our previous findings in type 1/2 patients. However, we could show an association between TNF alpha(308) polymorphism and the phenotype of common type 2 diabetes.

Aged↗
PubMed2003

Growth hormone replacement therapy induces insulin resistance by activating the glucose-fatty acid cycle.

The effects of GH replacement therapy on energy metabolism are still uncertain, and long-term benefits of increased muscle mass are thought to outweigh short-term negative metabolic effects. This study was designed to address this issue by examining both short-term (1 wk) and long-term (6 months) effects of a low-dose (9.6 micro g/kg body weight.d) GH replacement therapy or placebo on whole-body glucose and lipid metabolism (oral glucose tolerance test and euglycemic hyperinsulinemic clamp combined with indirect calorimetry and infusion of 3-[(3)H]glucose) and on muscle composition and muscle enzymes/metabolites, as determined from biopsies obtained at the end of the clamp in 19 GH-deficient adult subjects. GH therapy resulted in impaired insulin-stimulated glucose uptake at 1 wk (-52%; P = 0.008) and 6 months (-39%; P = 0.008), which correlated with deterioration of glucose tolerance (r = -0.481; P = 0.003). The decrease in glucose uptake was associated with an increase in lipid oxidation at 1 wk (60%; P = 0.008) and 6 months (60%; P = 0.008) and a concomitant decrease in glucose oxidation. The deterioration of glucose metabolism during GH therapy also correlated with the enhanced rate of lipid oxidation (r = -0.508; P = 0.0002). In addition, there was a shift toward more glycolytic type II fibers during GH therapy. In conclusion, replacement therapy with a low-dose GH in GH-deficient adult subjects is associated with a sustained deterioration of glucose metabolism as a consequence of the lipolytic effect of GH, resulting in enhanced oxidation of lipid substrates. Also, a shift toward more insulin-resistant type II X fibers is seen in muscle. Glucose metabolism should be carefully monitored during long-term GH replacement therapy.

Adult↗
PubMed2003

Impaired cathepsin L gene expression in skeletal muscle is associated with type 2 diabetes.

To identify abnormally expressed genes associated with muscle insulin resistance or type 2 diabetes, we screened the mRNA populations using cDNA differential display combined with relative RT-PCR analysis from muscle biopsies of diabetes-prone C57BL/6J and diabetes-resistant NMRI mice fed with a high-fat or normal diet for 3 or 15 months. Six abnormally expressed genes were isolated from the mice after a 3-month fat feeding; one of them was cathepsin L. No significant difference in mRNA levels of these genes was observed between fat- and normal-diet conditions in either strains. However, cathepsin L mRNA levels in muscle were higher in normal diet-fed C57BL/6J mice compared with normal diet-fed NMRI mice at 3 months (0.72 +/- 0.04 vs. 0.51 +/- 0.04 relative units, P < 0.01, n = 8-10) and at 15 months (0.41 +/- 0.05 vs. 0.27 +/- 0.04 relative units, P = 0.01, n = 9-10). Further, cathepsin L mRNA levels in muscle correlated inversely with plasma glucose in both strains regardless of diets at 3 (r = -0.49, P < 0.01, n = 31) and 15 (r = -0.42, P = 0.007, n = 39) months. To study whether cathepsin L plays a role in human diabetes, we measured cathepsin L mRNA levels in muscle biopsies taken before and after an insulin clamp from 12 monozygotic twin pairs discordant for type 2 diabetes and from 12 control subjects. Basal cathepsin L mRNA levels were not significantly different between the study groups. Insulin infusion increased cathepsin L mRNA levels in control subjects from 1.03 +/- 0.30 to 1.90 +/- 0.32 relative units (P = 0.03). Postclamp cathepsin L mRNA levels were lower in diabetic twins but similar in nondiabetic twins compared with control subjects (0.66 +/- 0.22, 1.16 +/- 0.18 vs. 1.38 +/- 0.21 relative units, P < 0.02, NS, respectively). Further, postclamp cathepsin L mRNA levels were correlated with insulin-mediated glucose uptake (r = 0.37, P = 0.03), particularly, with glucose oxidation (r = 0.37, P = 0.03), and fasting glucose concentrations (r = -0.45, P < 0.01) across all three study groups. In conclusion, muscle cathepsin L gene expression is increased in diabetes-prone mice and related to glucose tolerance. In humans, insulin-stimulated cathepsin L expression in skeletal muscle is impaired in diabetic but not in nondiabetic monozygotic twins, suggesting that the changes may be secondary to impaired glucose metabolism.

Animals↗
PubMed2003

Development of new peripheral arterial occlusive disease in patients with type 2 diabetes during a mean follow-up of 11 years.

OBJECTIVE: To assess the occurrence and development of new peripheral arterial occlusive disease (PAOD), its risk factors, and the outcome in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 130 type 2 diabetic patients (mean age 58 years) were examined at baseline and after a mean follow-up of 11 years (range 7-14). The ankle-brachial index (ABI) and toe-brachial index were used to detect PAOD. Blood and urine samples were taken at baseline, and a history of cardiovascular events was recorded during follow-up. RESULTS: PAOD was diagnosed in 21 (16%) patients at baseline. During follow-up, 21 of 89 (24%) patients developed new PAOD. There were 29 patients who died, 21 (72%) of them from cardiovascular disease. Patients with PAOD suffered an excess mortality compared with patients without PAOD (58 vs. 16%; P < 0.001). Logistic regression analysis showed that PAOD at baseline was associated with age, duration of diabetes, smoking, and urinary albumin excretion rate. Patients who developed new PAOD during follow-up had higher serum LDL cholesterol concentrations and lower HDL cholesterol concentrations and were older than the patients who remained free of PAOD. CONCLUSIONS: Objectively measured PAOD is frequent in type 2 diabetic patients. It presents the early clinical signs of atherosclerosis and is strongly associated with cardiovascular death. The risk factor pattern for PAOD was different at baseline and after a mean follow-up of 11 years. We consider routine ABI measurements and modification of risk factors necessary also in patients with asymptomatic PAOD.

Age of Onset↗
PubMed2003

Importance of obtaining independent measures of insulin secretion and insulin sensitivity during the same test: results with the Botnia clamp.

OBJECTIVE: To validate and apply a method for independent assessment of insulin secretion and insulin sensitivity (S(I)) during the same test; that is, an intravenous glucose tolerance test followed by a euglycemic-hyperinsulinemic clamp, also called the Botnia clamp. This test was then applied to nondiabetic subjects with (FH+) and without (FH-) a first-degree family history of diabetes. RESEARCH DESIGN AND METHODS: The Botnia clamp measures the first-phase insulin response (FPIR) to 0.3g/kg glucose i.v. and insulin sensitivity (M-value) from a 2-h euglycemic clamp begun 60 min after the glucose bolus. The M-value obtained during the Botnia clamp was compared with M-values obtained during a regular euglycemic clamp without prior glucose bolus. Repeated tests were performed in random order in subjects with normal and abnormal glucose tolerance. Finally, the test was applied to subjects with and without a family history of type 2 diabetes. RESULTS: S(I) and insulin secretion from this test showed a high degree of reproducibility, and the M-value obtained with the Botnia clamp correlated strongly with the M-value from a euglycemic clamp without prior glucose bolus (r = 0.953, P < 0.005). FH+ subjects showed decreased S(I) (P = 0.02), but similar FPIR, compared with FH- subjects. However, insulin secretion adjusted for the degree of insulin resistance was significantly impaired (P = 0.04). CONCLUSIONS: In conclusion, the Botnia clamp provides reliable and independent measures of S(I) and beta-cell function during the same test. As illustrated above, knowledge of the degree of S(I) is mandatory when presenting data on insulin secretion.

Diabetes Mellitus↗
PubMed2003

Associations of dietary fiber with glucose metabolism in nondiabetic relatives of subjects with type 2 diabetes: the Botnia Dietary Study.

OBJECTIVE: To study cross-sectional associations of dietary fiber intake with insulin resistance, insulin secretion, and glucose tolerance in a population at high risk for type 2 diabetes. RESEARCH DESIGN AND METHODS: The subjects consisted of 248 male and 304 female adult nondiabetic relatives of patients with type 2 diabetes. Dietary intake was measured by means of two 3-day food records. Associations of total, water-insoluble, and water-soluble fiber with measures of glucose metabolism based on an oral glucose tolerance test, were analyzed by multiple linear regression analysis adjusting for sex, age, length of education, physical activity, BMI, waist-to-hip ratio, systolic blood pressure, and serum triglyceride and HDL cholesterol concentrations. The homeostasis model assessment insulin resistance index, the incremental 30-min serum insulin concentration divided by the incremental 30-min glucose concentration, and fasting and 2-h glucose concentrations were the outcome variables. RESULTS: The dietary intake of total as well as water-insoluble and water-soluble fiber was inversely associated with insulin resistance: -0.17 (0.07), P = 0.012; -0.15 (0.07), P = 0.024; and -0.14 (0.07), P = 0.049 [regression coefficients (SE)]. Fiber variables were unrelated to insulin secretion and plasma glucose concentrations. CONCLUSIONS: The results support evidence that a high intake of dietary fiber is associated with enhanced insulin sensitivity and therefore may have a role in the prevention of type 2 diabetes.

Adult↗
PubMed2002

[A case report. Rosiglitazone treatment was highly effective yet had to be terminated].

The thiazolidinediones were introduced as oral hypoglycemic drugs in Sweden during the fall of 2000. A case is reported in which a woman with insulin-dependent type-2 diabetes and both macro- and microangiopathy and pronounced insulin resistance was treated with rosiglitazone (Avandia). Within three months insulin doses could be reduced by 36% (from 176 to 112 units insulin daily) and concomitantly Ery-HbA1c was reduced from 8.4 to 5.3%. In spite of this dramatic effect on glucose homeostasis administration of the drug had to be discontinued due to critical congestive heart failure.

Administration, Oral↗
PubMed2002

Plasma ProANP(1-30) reflects salt sensitivity in subjects with heredity for hypertension.

The aim of the present study was to investigate whether plasma concentration of proANP(1-30), the N-terminal fragment of the atrial natriuretic peptide prohormone, or 24-hour urinary excretion of urodilatin reflects the degree of salt sensitivity in hypertension-prone individuals. Plasma concentration of proANP(1-30) and urinary urodilatin excretion were determined at baseline, after 1 week on a low-salt diet (10 mmol/d) and after another week on a high-salt diet (240 mmol/d) in 30 healthy subjects with heredity for hypertension. Salt sensitivity was defined as the difference between mean arterial blood pressure after the high-salt diet and the mean arterial blood pressure after the low-salt diet. High- versus low-salt intake increased proANP(1-30) (668+/-330 versus 358+/-150 pmol/L; P<0.00001) and urodilatin (18.7+/-5.2 versus 16.0+/-8.3 pmol/24 h; P<0.05). ProANP(1-30) correlated with salt sensitivity at baseline (r=0.76, P<0.000001), after the low- (r=0.80, P<0.0000001) and high-salt diets (r=0.85, P<0.00000001). The increase in proANP(1-30) induced by changing from the low- to the high-salt diet was also directly related to salt sensitivity (r=0.78, P<0.000001). ProANP(1-30) was not related to urinary sodium excretion. Neither urodilatin nor the sodium-induced change in urodilatin correlated with salt sensitivity. However, urodilatin was related to the urinary sodium excretion at baseline (r=0.58, P<0.01) and after the high-salt diet (r=0.62, P<0.001). In conclusion, the close correlations between proANP(1-30) and salt sensitivity suggest that proANP(1-30) may serve as a marker for salt sensitivity and could be useful in identifying subjects who would benefit from dietary salt restriction to prevent development of hypertension.

Adult↗
PubMed2002

Down-regulation of insulin receptor substrates (IRS)-1 and IRS-2 and Src homologous and collagen-like protein Shc gene expression by insulin in skeletal muscle is not associated with insulin resistance or type 2 diabetes.

To examine whether altered gene expression of insulin receptor substrates (IRS)-1 and IRS-2 and Src homologous and collagen-like protein Shc is an inherited trait and is associated with muscle insulin resistance or type 2 diabetes, we measured mRNA levels of these genes by a relative quantitative RT-PCR method in muscle biopsies taken before and after an insulin clamp from 12 monozygotic twin pairs discordant for type 2 diabetes and 12 control subjects. Insulin-stimulated glucose uptake was decreased both in the diabetic and nondiabetic twin, compared with healthy control subjects (5.2 +/- 0.7 and 8.5 +/- 0.8 vs. 11.4 +/- 0.9 mg/kg x min(-1); P < 0.01 and P < 0.02, respectively). Basal mRNA levels of IRS-1, IRS-2, and Shc were similar in the diabetic and nondiabetic twins as well as in the control subjects. Insulin decreased mRNA expression of IRS-1 by 72% (from 0.75 +/- 0.06 to 0.21 +/- 0.04 relative units; P < 0.001), IRS-2 by 71% (from 0.55 +/- 0.10 to 0.16 +/- 0.08 relative units; P < 0.03), and Shc by 25% (from 0.95 +/- 0.04 to 0.71 +/- 0.04 relative units; P < 0.01) vs. baseline as demonstrated in the control subjects. The postclamp Shc mRNA level was slightly higher in the diabetic twins (P = 0.05) but similar in the nondiabetic twins, as compared with the control subjects, whereas postclamp IRS-1 and IRS-2 mRNA levels were similar between the study groups. There was an inverse correlation between postclamp Shc mRNA concentration and glucose uptake (r = -0.53, P = 0.01; n = 22) in the controls and nondiabetic twins. However, the decrease in Shc gene expression by insulin was not significantly different between the study groups. In conclusion, because insulin down-regulates IRS-1, IRS-2, and Shc gene expression in skeletal muscle in diabetic and nondiabetic monozygotic twins and control subjects to the same extent, it is unlikely that expression of these genes is an inherited trait or contributes to skeletal muscle insulin resistance.

Adaptor Proteins, Signal Transducing↗
PubMed2002

FOXC2 mRNA Expression and a 5' untranslated region polymorphism of the gene are associated with insulin resistance.

The human transcription factor FOXC2 has recently been shown to protect against diet-induced insulin resistance in transgenic mice. We investigated the expression of FOXC2 in fat and muscle and performed a genetic analysis in human subjects. FOXC2 mRNA levels were increased in visceral compared with subcutaneous fat from obese subjects (12 +/- 4-fold; P = 0.0001), and there was a correlation between whole-body insulin sensitivity and FOXC2 mRNA levels in visceral fat (fS-insulin R = -0.64, P = 0.01, and homeostasis model assessment of insulin resistance [HOMA-IR] R = -0.68, P = 0.007) and skeletal muscle (fS-insulin R = -0.57, P = 0.03, and HOMA-IR R = -0.55, P = 0.04). Mutation screening of the FOXC2 gene identified a common polymorphism in the 5' untranslated region (C-512T). The T allele was associated with enhanced insulin sensitivity (HOMA-IR P = 0.007) and lower plasma triglyceride levels in females (P = 0.007). Also, the higher expression of FOXC2 in visceral than in subcutaneous fat was restricted to subjects homozygous for the T allele (P = 0.03 vs. P = 0.7). Our data suggest that increased FOXC2 expression may protect against insulin resistance in human subjects and that genetic variability in the gene may influence features associated with the metabolic syndrome.

5' Untranslated Regions↗