Project description:Background. Differential gene expression in adipose tissue during diet-induced weight loss followed by a weight stability period is not well characterized. Markers of these processes may provide a deeper understanding of the underlying mechanisms. Objective. To identify differentially expressed genes in human adipose tissue during weight loss and weight maintenance after weight loss. Design. RNA from subcutaneous abdominal adipose tissue from nine obese subjects was obtained and analyzed at baseline, after weight reduction on a low calorie diet (LCD), and after a period of group therapy in order to maintain weight stability. Results. Subjects lost 18.8 + 5.4% of their body weight during the LCD and maintained this weight during group therapy. Insulin sensitivity (HOMA) improved after weight loss with no further improvement during weight maintenance. Cyclin-dependent kinase inhibitor 2B (CDKN2B) and JAZF zinc finger 1 (JAZF1), associated with type 2 diabetes, were downregulated. We could also confirm the downregulation of candidates for obesity and related traits, such as tenomodulin (TNMD) and matrix metallopeptidase 9 (MMP9), with weight loss. The expression of other candidates, such as cell death-inducing DFFA-like effector A (CIDEA) and stearoyl-CoA desaturase (SCD) were upregulated during weight loss but returned to baseline levels during weight maintenance. Conclusion. Genes in the adipose tissue are differentially expressed during weight loss and weight maintenance after weight loss. Genes that show sustained regulation may be of potential interest as markers of the beneficial effects of weight loss whereas others seem to be primarily involved in the process of weight loss itself. Nine participants were prescribed a low calorie diet (LCD) containing 1200 kcal/day for approximately three months (101 ± 26 days). Following the weight reduction phase the participants attended a six month follow-up period (167 ± 37 days). By protocol design, subjects were eligible to enter the study if they had lost at least 10% of their initial body weight during the LCD-period and maintained this weight (+5%) after group therapy. Subcutaneous adipose tissue samples were obtained at three time-points: (i) at baseline, (ii) after weight reduction when subjects were no longer losing weight, and (iii) after the group therapy weight maintenance phase.

Project description:We investigated the regulation of adipose tissue (AT) gene expression during different phases of a dietary weight loss program and its relationship with insulin sensitivity. Obese women followed a weight reduction program composed of an energy restriction phase (ER) with a 4-week very-low-calorie diet and a weight stabilization period (WS) composed of a 2-month low-calorie diet followed by 3 to 4 months of a weight maintenance diet. At each time point, body composition, plasma parameters and glucose disposal rate were assessed and subcutaneous AT biopsies were performed. Variations in mRNA levels were determined using DNA microarrays and reverse transcription-quantitative PCR. Distinct sets of AT genes are regulated during calorie restriction and weight stabilization revealing an unexpected temporal pattern in the link between AT and insulin sensitivity during weight loss. Experiment Overall Design: Fifteen obese premenopausal women were recruited at the Third Faculty of Medicine of Charles University and at the Institute for Mother and Child Care in Prague, Czech Republic. During the first four weeks of the dietary intervention program, the subjects received an energy restricted diet of 800 kcal/day (liquid formula diet, Redita, Promil). During the next two months, a low-calorie diet was designed to provide 600 kcal/day less than the individually estimated energy requirement based on an initial resting metabolic rate multiplied by 1.3. Following this, subjects entered a weight maintenance phase for a period of 3 to 4 months, during which the patients were instructed to keep their weight stable. A complete clinical investigation in the fasting state was realized before and at the end of each phase. Needle microbiopsy of subcutaneous AT was performed under local anesthesia (1% Xylocaine) from the abdominal region (14â20 cm lateral to the umbilicus). Total RNA were isolated from AT samples with Qiagen RNeasy kit. RNA quantity and quality were checked with the Experion automated electrophoresis system (BioRad laboratories). We performed a whole transcriptome analysis comparing 1) before vs. after the initial 4 weeks severe energy restriction (ER), 2) after energy restriction vs. after weight stabilization (WS) and 3) before dietary intervention vs. after weight stabilization (DI). Eight subjects representative of the cohort were selected, matched for high quality of total RNA samples, insulin sensitivity and weight changes during the study. Targets for microarray experiments were generated from 500 ng of total RNA with Agilent low RNA input amplification kit (Agilent Technologies) and hybridized to whole genome 44k oligonucleotide arrays (Agilent Technologies). Each combination of samples was analyzed twice using a dye swap design (i.e., a total of 48 hybridizations). Data acquisition from microarrays was obtained with a GenePix 4000B scanner (Axon instruments) and image processing was performed with Feature Extraction 8.5 (Agilent Technologies). Raw data were normalized with a global Lowess procedure and filtered with R package LIMMA (Bioconductor). Outlier replicates and spots with a signal to noise ratio lesser than 2 on both red and green channel were eliminated from our analyses. Mean log ratios were calculated from paired duplicates before normalization. Differentially expressed genes were identified with Significance Analysis of Microarray (SAM) procedure.

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Homo sapiens

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