The results of two independent DNA-microarray experiments concerning adipogenesis in the murine preadipocyte 3T3-L1 cell line, which covered the first two days after the induction of differentiation, were analyzed using the multidimensional scaling (MDS) method. In both data arrays, the first three scaling components accounted for 73.5–73.8% of the total dispersion. This result implies that both arrays of the gene expression profiles are in fact three-dimensional and each component reflects a definite principal process involved in one of the three early stages of adipogenesis: (i) determination of the fibroblast-like stem cells, (ii) clonal expansion of adipoblasts, and (iii) preadipocyte conversion into a mature adipocyte phenotype. Each profile of the gene expression is characterized by coefficients of correlation with the first three scaling components. The functional annotation in terms of the Gene Ontology database profiles (sorted according to the correlations with each component) generally corresponds to a regular change of elementary biological processes during the three early stages of adipogenesis. Analysis of correlations with the principal scaling components for the genes previously classified as subject to differential expression in the course of adipogenesis in mice suggests a complicated role of these genes in early adipogenesis (in some cases, described in the literature). The MDS analysis of the gene expression profiles and the analysis of correlations between these profiles and the main scaling components provides a deeper insight into the fine role of these genes and makes possible the search for new biomarkers of various differentiation stages.
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