The factors that control fat deposition in adipose tissues are poorly understood. It is known that visceral adipose tissues display a range of biochemical properties that distinguish them from adipose tissues of subcutaneous origin. However, we have little information on gene expression, either in relation to fat deposition or on interspecies variation in fat deposition. The first step in this study was to identify genes expressed in fat depot of cattle using the differential display RT-PCR method. Among the transcripts identified as having differential expression in the two adipose tissues were cell division cycle 42 homolog (CDC42), prefoldin-5, decorin, phosphate carrier, 12S ribosomal RNA gene, and kelch repeat and BTB domain containing 2 (Kbtbd2). In subsequent experiments, we determined the expression levels of these latter genes in the pig and in mice fed either a control or high-fat diet to compare the regulation of fat accumulation in other animal species. The levels of CDC42 and decorin mRNA were found to be higher in visceral adipose tissue than in subcutaneous adipose tissue in cattle, pig, and mice. However, the other genes studied did not show consistent expression patterns between the two tissues in cattle, pigs, and mice. Interestingly, all genes were upregulated in subcutaneous and/or visceral adipose tissues of mice fed the high-fat diet compared with the control diet. The data presented here extend our understanding of gene expression in fat depots and provide further proof that the mechanisms of fat accumulation differ significantly between animal species. differential display and reverse transcriptase-polymerase chain reaction; fat depot THERE ARE TWO TYPES OF ADIPOSE TISSUE, subcutaneous and visceral. Recent studies indicate that adipocytes in these two fat depots show differences in basal metabolic properties, for example, in regulating volume, lipid composition, and so on (22,24). There is considerable current interest in visceral adipose tissue because of its relationship with various diseases such as cardiovascular disease, type 2 diabetes mellitus, hyperlipidemia, and syndrome X. There are a number of potential reasons why visceral adipose tissue may contribute to abnormalities in metabolism; among these are its anatomical site and pattern of venous drainage, and the presence of intrinsic and unique features of visceral adipocytes. The venous drainage of visceral adipose tissue is via the portal system, directly providing free fatty acid as a substrate for hepatic lipoprotein metabolism and glucose production (16,22,24). Additionally, in vitro studies using labeled tracers have demonstrated that visceral adipocytes have higher rates of lipid turnover than subcutaneous adipose tissue (19,20).Fat depot metabolism is also of importance in the commercial rearing of livestock such as cattle and pigs. One of the most important themes in the animal industry is the production of high quality meat at low cost. A better understanding of the specific accumulation mechanisms of fat depots should c...
