Modulation of double-stranded RNA-activated protein kinase in insulin sensitive tissues of obese humans.

OBJECTIVE: The double-stranded RNA-dependent protein kinase (PKR) was recently implicated in regulating molecular integration of nutrient- and pathogen-sensing pathways in obese mice. However, its modulation in human tissues in situations of insulin resistance has not been investigated. The present study was performed to first determine the tissue expression and phosphorylation levels of PKR in the liver, muscle, and adipose tissue in obese humans, and also the modulation of this protein in the adipose tissue of obese patients after bariatric surgery. DESIGN AND METHODS: Eleven obese subjects who were scheduled to undergo Roux-en-Y Gastric Bypass Procedure participated in this study. Nine apparently healthy lean subjects as a control group were also included. RESULTS: Our data show that PKR is activated in liver, muscle, and adipose tissue of obese humans and, after bariatric surgery, there is a clear reduction in PKR activation accompanied by a decrease in protein kinase-like endoplasmic reticulum kinase, c-Jun N-terminal kinase, inhibitor of kappa ß kinase, and insulin receptor substrate-1 serine 312 phosphorylation in subcutaneous adipose tissue from these patients. CONCLUSION: Thus, it is proposed that PKR is an important mediator of obesity-induced insulin resistance and a potential target for the therapy.

CYP19 gene expression in subcutaneous adipose tissue is associated with blood pressure in women with polycystic ovary syndrome.

In polycystic ovary syndrome (PCOS), hypertension has been linked to androgen excess and insulin resistance. Aromatase, an enzyme encoded by the CYP19 gene, affects androgen metabolism and estrogen synthesis, influencing the androgen to estrogen balance. We characterized CYP19 gene expression in subcutaneous adipose tissue of women with PCOS and normal controls and evaluated the association between subcutaneous fat CYP19 mRNA, circulating hormone levels, and blood pressure. This case-control study was carried out with 31 PCOS patients and 27 BMI-matched normotensive non-hirsute women with regular cycles. Participants underwent anthropometric measurements, collection of blood samples, and adipose tissue biopsy (28 PCOS and 19 controls). Hypertension was defined as systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure ≥ 85 mmHg. PCOS patients were divided into normotensive and hypertensive. Main outcome measures were serum estrogen and androgen levels, estrogen-to-androgen ratio, and CYP19 gene expression in subcutaneous fat. Subcutaneous CYP19 mRNA was higher in hypertensive PCOS than in control and normotensive PCOS women (p = 0.014). Estrogen-to-androgen ratio was lower in hypertensive PCOS than controls (p < 0.003). Estrogen-to-androgen ratio ≤ 0.06 (median for the three groups) was observed in 91% of hypertensive PCOS women, vs. 37% and 61% in the control and normotensive PCOS groups (p = 0.011). CYP19 gene expression in subcutaneous fat of PCOS patient correlated positively with systolic (p = 0.006) and diastolic blood pressure (p = 0.009). Androgen excess and hyperinsulinemia may play a role in the molecular mechanisms that activate aromatase mRNA transcription in abdominal fat tissue.

Overexpression of 11beta-hydroxysteroid dehydrogenase type 1 in hepatic and visceral adipose tissue is associated with metabolic disorders in morbidly obese patients.

BACKGROUND: The enzyme 11-beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyzes intracellular glucocorticoid reactivation by conversion of cortisone to cortisol in different tissues and have been implicated in several metabolic disorders associated with obesity. The aim of this study was to evaluate the 11beta-HSD1 expression in liver, visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) in morbidly obese patients undergoing bariatric surgery and its correlations with clinical, anthropometric, and biochemical variables. METHODS: A prospective study was conducted over a 27-month period. Hepatic, VAT, and SAT samples were obtained at the time of surgery. 11beta-HSD1 and 18S gene expression was measured using real-time quantitative reverse transcriptase-polymerase chain reaction. RESULTS: Forty nine patients met the inclusion criteria [mean age: 42.2 +/- 10 years, body mass index (BMI): 42 +/- 6 kg/m(2), 71% women and 63% with metabolic syndrome (MS)]. 11beta-HSD1 mRNA levels were higher in liver than fat tissue (p < 0.001), being higher in SAT than in VAT (p < 0.001) without gender-specific differences. Hepatic expression of 11beta-HSD1 correlated positively with SAT and VAT, alanine aminotransferase (ALT), and serum glucose and was inversely associated with BMI. 11beta-HSD1 mRNA in VAT correlated positively with insulinemia, ALT, and LDL cholesterol. There were no associations between 11beta-HSD1 mRNA in SAT and the variables analyzed. CONCLUSIONS: 11beta-HSD1 expression is higher in liver in comparison to adipose tissue in obese patients. The observed correlations between hepatic and VAT 11beta-HSD1 expression with dyslipidemia and insulin resistance suggest that this enzyme might have a pathogenic role in obesity and related metabolic disorders.

11beta-hydroxysteroid dehydrogenase type 1 is overexpressed in subcutaneous adipose tissue of morbidly obese patients.

BACKGROUND: 11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) enzyme catalyzes interconversion of inactive cortisone to active cortisol. Its expression in adipose tissue has been associated with obesity and some of its metabolic disorders. Controversies regarding which fat depots [subcutaneous adipose tissue (SAT) or visceral adipose tissue (VAT)] have higher expression still remain. The aim of this work was to evaluate 11beta-HSD1 expression in SAT and VAT of obese patients and evaluate its association to metabolic features of metabolic syndrome. METHODS: In 32 morbidly obese patients, paired samples of SAT and VAT were collected. All patients, 40.2+/-12.3 years and 36.7+/-3.8 body mass index (BMI), underwent sleeve gastrectomy or laparoscopic gastric bypass. Gene expression of 11beta-HSD1 in adipose tissue samples were determined by real-time reverse transcriptase polymerase chain reaction. Spearman correlation test was used to evaluate relationships between 11beta-HSD1 levels and clinical and biochemical parameters. RESULTS: 11beta-HSD1 mRNA levels were higher in SAT than in VAT, with median expression levels of 11.4 arbitrary units (AU) and 7.8 AU, respectively (p=0.03). SAT 11beta-HSD1 mRNA were correlated with VAT mRNA levels (r=-0.6, p=0.018) and hip circumference (r=0.66, p=0.018). SAT 11beta-HSD1 levels increase parallel according to BMI category. We did not find a correlation between SAT or VAT with fasting glucose (r=0.15, p=NS), total cholesterol (r=0.13, p=NS), triglycerides (r=0.04, p=NS), and high-density lipoprotein (r=-0.16, p=NS). However, SAT expression in patients with features of MS was higher than those without features of MS. CONCLUSIONS: Our results demonstrate that SATs express higher 11beta-HSD1 mRNA levels than VAT. This finding highlights the importance of SAT in obesity and its possible role on metabolic disorders associated with obesity.