Global gene expression patterns spanning 3T3-L1 preadipocyte differentiation

Adipogenesis is of significant relevance from an agricultural perspective. Traits such as subcutaneous fat thickness, marbling and waste fat are of substantial economic importance in animal production. In order to discover more about the genetic basis of this process, a study was undertaken to examine the changes that occur daily in global gene expression as 3T3-L1 cells differentiate from preadipocyte to adipocyte. Duplicate RNA samples were collected daily during the differentiation process and probed with the Affymetrix U74Av2 GeneChip® microarray to allow the time-course analysis of the gene expression profile in these differentiating cells. Self-organizing maps (SOM) clustering was performed to extract patterns of expression over the course of the experiment (day 0 to day 6). The clustering generated nine distinct expression patterns containing between 74 and 420 genes/ESTs. Functional clusters and important chronological changes in the expression of key genes and gene groups were identified. The pattern of expression observed for many genes not only confirmed what has been shown previously for the early stages of differentiation, but also expanded this pattern to cover the whole differentiation process thus giving a very comprehensive overview of patterns and changes in gene expression over the time course of adipocyte differentiation. Key words: Adipocyte differentiation, gene expression, SOM clustering