Gene expression profile of mouse white adipose tissue during inflammatory stress: age‐dependent upregulation of major procoagulant factors

Tolerance to physiological stress resulting from inflammatory disease decreases significantly with age. High mortality rates, increased cytokine production, and pronounced thrombosis are characteristic complications of aged mice with acute systemic inflammation induced by injection with lipopolysaccharide (LPS). As adipose tissue is now recognized as an important source of cytokines, we determined the effects of aging on visceral white adipose tissue gene expression during LPS‐induced inflammation in male C57BL/6 mice. Microarray analysis revealed that the expression of 6025 genes was significantly changed by LPS; of those, the expression of 667 showed an age‐associated difference. Age‐associated differences were found in many genes belonging to the inflammatory response and blood clotting pathways. Genes for several procoagulant factors were upregulated by LPS; among these, tissue factor, thrombospondin‐1, and plasminogen activator inhibitors‐1 and ‐2, exhibited age‐associated increases in expression which could potentially contribute to augmented thrombosis. Further analysis by qRT–PCR, histological examination, and cell fraction separation revealed that most inflammatory and coagulant‐related gene expression changes occur in resident stromal cells rather than adipocytes or infiltrating cells. In addition, basal expression levels of 303 genes were altered by aging, including increased expression of component of Sp100‐rs (Csprs). This study indicates that adipose tissue is a major organ expressing genes for multiple inflammatory and coagulant factors and that the expression of many of these is significantly altered by aging during acute inflammation. Data presented here provide a framework for future studies aimed at elucidating the impact of adipose tissue on age‐associated complications during sepsis and systemic inflammation.     

Cryopreservation of adipose tissue

The main obstacle to achieving favorable outcome of soft-tissue augmentation after autologous fat transplantation is unpredictable long-term results due to the high rate of absorption in the grafted site. At the present time, adipose aspirates can only be used for immediate autologous fat grafting during the same procedure in which liposuction is performed; therefore adipose aspirates obtained from the procedure are usually discarded. it has been a strong desire of both surgeons and patients to be able to preserve the adipose aspirates, if an optimal technique were available, for potential future applications. For the last several years, cryopreservation of adipose tissue has been studied extensively in the author''s laboratory. Several findings from this exciting translational research will lead to develop a reliable method for long-term preservation of adipose tissue in the future. in addition, successful long-term preservation of adipose tissue may open a new era in adipose tissue related tissue regeneration.     

Vaspin gene expression in human adipose tissue: association with obesity and type 2 diabetes

Recently, vaspin was identified as an adipokine with insulin-sensitizing effects, which is predominantly secreted from visceral adipose tissue in a rat model of type 2 diabetes. In this study, we examined whether vaspin mRNA expression is a marker of visceral obesity and correlates with anthropometric and metabolic parameters in paired samples of visceral and subcutaneous adipose tissue from 196 subjects with a wide range of obesity, body fat distribution, insulin sensitivity, and glucose tolerance. Vaspin mRNA expression was only detectable in 23% of the visceral and in 15% of the subcutaneous (SC) adipose tissue samples. Vaspin mRNA expression was not detectable in lean subjects (BMI<25) and was more frequently detected in patients with type 2 diabetes. No significant correlations were found between visceral vaspin gene expression and visceral fat area or SC vaspin expression. However, visceral vaspin expression significantly correlates with BMI, % body fat, and 2 h OGTT plasma glucose. Subcutaneous vaspin mRNA expression is significantly correlated with WHR, fasting plasma insulin concentration, and glucose infusion rate during steady state of an euglycemic-hyperinsulinemic clamp. Multivariate linear regression analysis revealed % body fat as strongest predictor of visceral vaspin and insulin sensitivity as strongest determinant of SC vaspin mRNA expression. In conclusion, our data indicate that induction of human vaspin mRNA expression in adipose tissue is regulated in a fat depot-specific manner and could be associated with parameters of obesity, insulin resistance, and glucose metabolism.     

Differential expression of adipose tissue proteins between obesity-susceptible and -resistant rats fed a high-fat diet

One of the major questions in the field of obesity is why some humans become obese (obesity prone, OP) and others resist the development of obesity (obesity resistant, OR) when exposed to a high-calorie diet, which has not been completely studied. Therefore, in the present study, in order to gain insight into the molecular mechanisms underlying this propensity, we have performed a comparative analysis of protein expression profiles in white adipose tissue (WAT) and brown adipose tissue (BAT) of rats fed a high-fat diet by 2-DE and MALDI-TOF-MS. Protein mapping of homogenates revealed significant alterations to a number of proteins; 60 and 70 proteins were differentially regulated in BAT and WAT, respectively. For careful interpretation of proteomic results, we categorized the identified proteins into two groups by analysis of both average spot density of pooled six rat adipose tissues and individual spot density of each adipose tissue of six rats as a function of body weight. One of the most striking findings of this study was that significant changes of Ehd1 and laminin receptor in BAT as well as antiquitin, DJ-1 protein, and paraoxonase 2 in WAT were found for the first time in obese rats. In addition, we confirmed the increased expression of some thermogenic enzymes and decreased lipogenic enzymes in adipose tissues of OR rats by immunoblot analysis. To our knowledge, this is the first proteomic study of profiling of protein modulation in OP and OR rats, thereby providing the first global evidence for different propensities to obesity between OP and OR rats.     

Evaluation of light regulatory potential of Calvin cycle steps based on large-scale gene expression profiling data

Although large-scale gene expression data have been studied from many perspectives, they have not been systematically integrated to infer the regulatory potentials of individual genes in specific pathways. Here we report the analysis of expression patterns of genes in the Calvin cycle from 95 Arabidopsis microarray experiments, which revealed a consistent gene regulation pattern in most experiments. This identified pattern, likely due to gene regulation by light rather than feedback regulations of the metabolite fluxes in the Calvin cycle, is remarkably consistent with the rate-limiting roles of the enzymes encoded by these genes reported from both experimental and modeling approaches. Therefore, the regulatory potential of the genes in a pathway may be inferred from their expression patterns. Furthermore, gene expression analysis in the context of a known pathway helps to categorize various biological perturbations that would not be recognized with the prevailing methods.     

Expression profiling analysis for genes related to meat quality and carcass traits during postnatal development of backfat in two pig breeds

The competitive equilibrium of fatty acid biosynthesis and oxidation in vivo determines porcine sub-cutaneous fat thickness(SFT) and intramuscular fat(IMF) content.Obese and lean-type pig breeds show obvious differences in adipose deposition;however, the molecular mechanism underlying this phenotypic variation remains unclear.We used pathway-focused oligo microarray studies to examine the expression changes of 140 genes associated with meat quality and carcass traits in backfat at five growth stages(1―5 months) of Landrace(a leaner, Western breed) and Taihu pigs(a fatty, indigenous, Chinese breed).Variance analysis(ANOVA) revealed that differences in the expression of 25 genes in Landrace pigs were significant(FDR adjusted permutation, P<0.05) among 5 growth stages.Gene class test(GCT) indicated that a gene-group was very significant between 2 pig breeds across 5 growth stages(PErmineJ<0.01), which consisted of 23 genes encoding enzymes and regulatory proteins associ-ated with lipid and steroid metabolism.These findings suggest that the distinct differences in fat deposition ability between Landrace and Taihu pigs may closely correlate with the expression changes of these genes.Clustering analysis revealed a very high level of significance(FDR adjusted, P<0.01) for 2 gene expression patterns in Landrace pigs and a high level of significance(FDR adjusted, P<0.05) for 2 gene expression patterns in Taihu pigs.Also, expression patterns of genes were more diversified in Taihu pigs than those in Landrace pigs, which suggests that the regulatory mechanism of micro-effect polygenes in adipocytes may be more complex in Taihu pigs than in Landrace pigs.Based on a dy-namic Bayesian network(DBN) model, gene regulatory networks(GRNs) were reconstructed from time-series data for each pig breed.These two GRNs initially revealed the distinct differences in physiological and biochemical aspects of adipose metabolism between the two pig breeds;from these results, some potential key genes could be identified.Quantitative, real-time RT-PCR(QRT-PCR) was used to verify the microarray data for five modulated genes, and a good correlation between the two measures of expression was observed for both 2 pig breeds at different growth stages(R=0.874±0.071).These results highlight some possible candidate genes for porcine fat characteristics and provide some data on which to base further study of the molecular basis of adipose metabolism.     

Rnf20 deficiency in adipocyte impairs adipose tissue development and thermogenesis

RNF20,an E3 ligase critical for monoubiquitination of histone H2B at lysine 120 (H2Bub),has been implicated in the regulation of various cellar processes;however,its physiological roles in adipocytes remain poorly characterized.Here,we report that the adipocyte-speci-fic knockout of Rnf20 (ASKO) in mice led to progressive fat loss,organomegaly and hyperinsulinemia.Despite signs of hyperinsulinemia,normal insulin sensitivity and improved glucose tolerance were observed in the young and aged CD-fed ASKO mice.In addition,high-fat diet-fed ASKO mice developed severe liver steatosis.More-over,we observed that the ASKO mice were extremely sensitive to a cold environment due to decreased expression levels of brown adipose tissue (BAT) selec-tive genes,including uncoupling protein 1 (Ucp1),and impaired mitochondrial functions.Significantly decreased levels of peroxisome proliferator-activated receptor gamma (Ppary) were observed in the gonadal white adipose tissues (gWAT) from the ASKO mice,suggesting that Rnf20 regulates adipogenesis,at least in part,through Ppary.Rosiglitazone-treated ASKO mice exhibited increased fat mass compared to that of the non-treated ASKO mice.Collectively,our results illus-trate the critical role of RNF20 in control of white and brown adipose tissue development and physiological function.     

Gene expression profiling in apoptotic k562 cells treated by homoharringtonine

Gene chip technology was used to determine the gene expression profiles in apoptotic K562 cells induced by homoharringtonine. The expression of forty-four mRNAs was found to be changed significantly were identified after screening with a gene chip capable of detecting 14,218 different human mRNA species simultaneously. Of these genes, 17 were up-regulated and 27 were down-regulated. Most of them were found to be related to apoptosis, oncogenes, or tumor suppression. Several genes with altered gene expression, such as human transforming growth factor-beta inducible early protein gene （TIEG）, vitamin D3 upregulated protein 1 gene （VDUP1）, RNA binding motif protein 4 gene （RBM4） and v-myc myelocytomatosis viral oncogene homolog （C-MFC）, were confirmed by Northern blot analysis. According to the dynamic gene expression pattern in these apoptotic cells, the activated transforming growth factor-β and tumor necrosis factor signaling pathways play an important role in homoharringtonine-induced apoptosis. TIEG was significantly altered after apoptosis induction, it should be critical for apoptosis signal transmission.     

Gene expression changes with age in skin,adipose tissue,blood and brain

Background

Previous studies have demonstrated that gene expression levels change with age. These changes are hypothesized to influence the aging rate of an individual. We analyzed gene expression changes with age in abdominal skin, subcutaneous adipose tissue and lymphoblastoid cell lines in 856 female twins in the age range of 39-85 years. Additionally, we investigated genotypic variants involved in genotype-by-age interactions to understand how the genomic regulation of gene expression alters with age.

Results

Using a linear mixed model, differential expression with age was identified in 1,672 genes in skin and 188 genes in adipose tissue. Only two genes expressed in lymphoblastoid cell lines showed significant changes with age. Genes significantly regulated by age were compared with expression profiles in 10 brain regions from 100 postmortem brains aged 16 to 83 years. We identified only one age-related gene common to the three tissues. There were 12 genes that showed differential expression with age in both skin and brain tissue and three common to adipose and brain tissues.

Conclusions

Skin showed the most age-related gene expression changes of all the tissues investigated, with many of the genes being previously implicated in fatty acid metabolism, mitochondrial activity, cancer and splicing. A significant proportion of age-related changes in gene expression appear to be tissue-specific with only a few genes sharing an age effect in expression across tissues. More research is needed to improve our understanding of the genetic influences on aging and the relationship with age-related diseases.     

Resistin expression in different adipose tissue depots during rat development

Resistin is a hormonal factor synthesised by adipocytes that was first thought to be related with the resistance to insulin in obesity, but whose function is not yet completely established. Here we have studied the ontogenic pattern of resistin mRNA expression in different white adipose tissue depots (WAT) – epididymal, inguinal, mesenteric and retroperitoneal – and in brown adipose tissue (BAT), as well as the circulating resistin levels, in rats of different ages (from the suckling period to one year of age). Resistin mRNA was determined by Northern blotting, and serum levels by enzyme immunoassay. In WAT, resistin expression remains almost constant with age, except in early development, where there is a peak of expression in the epididymal and retroperitoneal depots, and a decrease in the inguinal one, while the expression remains constant for the mesenteric depot. Moreover, there is a site-specific difference regarding resistin expression: all the depots express characteristic levels of mRNA, especially at the age of 2 months, the moment when resistin mRNA levels are significantly higher in the epididymal and the retroperitoneal than in the inguinal and mesenteric WAT and than in the BAT. The transient increased resistin expression in the epididymal and the retroperitoneal WAT at a period of time in which there is a change in diet (from milk to chow) suggests a common nutritional regulation of the resistin gene. Circulating resistin levels increase with age probably reflecting the increase in the body fat content.     

Comparison of methods for assessing abdominal adipose tissue from magnetic resonance images

Objective: To compare the inter‐rater and intra‐rater reliability and analysis time of two methods for quantifying visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) volumes from magnetic resonance (MR) images. Research Methods and Procedures: Ten subjects (BMI, 27.0 ± 2.1 kg/m²; 56 years of age ± 4 years) underwent MR imaging of the abdomen. Ten transverse T1‐weighted images were selected from each scan and analyzed using two software packages that differ in principle. The first method, ANALYZE version 5.0, represents the manual threshold method, and the second, HIPPO version 1.3, is based on the fuzzy clustering approach. Inter‐rater reliability for each method was assessed by comparing the intra‐class correlation coefficients (ICCs) for VAT and SAT results from two evaluators, and intra‐rater reliability for each method was assessed by comparing ICCs for VAT and SAT analyses performed 1 week apart by the same evaluator. The total time for analysis also was compared between methods. Results: The inter‐rater reliability for VAT was greater with HIPPO than with ANALYZE (ICC = 0.996 vs. 0.828), whereas inter‐rater reliability for SAT did not differ between methods (ICC = 0.975 and 0.987). The intra‐rater reliability was equally high with HIPPO and ANALYZE for both VAT (ICC = 0.998 vs. 0.992) and SAT (ICC = 0.996 vs. 0.992). HIPPO required less than one‐half as much analysis time as ANALYZE (15.9 ± 4.4 vs. 36.5 ± 8.2 minutes, p < 0.0001). Discussion: HIPPO software appears advantageous for the quantification of VAT from multislice MR images because inter‐rater results are more reliable, and it is more time‐efficient than less automated methods.     

Gene expression profiling of cardiovascular disease models

Recent development of gene expression profiling technologies has enabled the large-scale analysis of gene expression changes during disease progression. Frequently, cardiovascular diseases involve complex interactions of multiple cell types over prolonged periods of time. A better understanding of the pathology of cardiovascular diseases and the potential identification of underlying genetic defects are currently being explored by using profiling methodologies in a number of animal and tissue-culture models.