Analysis of gene and protein expression during monocyte-macrophage differentiation and cholesterol loading--cDNA and protein array study.

BACKGROUND: To better understand the role of macrophages in atherogenesis and to find new strategies to prevent their harmful effects, more information is needed about their gene and protein expression patterns in atherogenic conditions.
METHODS: We analyzed gene and protein expression changes during monocyte-macrophage differentiation and lipid-loading by cDNA arrays and antibody-based protein arrays, respectively.
RESULTS: It was found that early response genes, such as transcription factors, were upregulated early during monocyte-macrophage differentiation, while genes functioning in cell proliferation, migration, inflammation and lipid metabolism were activated later during macrophage differentiation. When comparing results from cDNA and antibody arrays, it become evident that changes at the protein levels were not always predicted by changes at the mRNA level. This discrepancy may be due to the different transcript variants that exist for distinct genes, posttranslational modifications and different turnover rates for mRNAs and proteins of distinct genes. When combining cDNA and protein array results with RT-PCR, it was found that CD36, COX-2, and several factors regulating cell signaling, such as Cdk-1, TFII-I, NEMO-like kinase, Elf-5 and TRADD were strongly upregulated both at the mRNA and protein levels.
CONCLUSIONS: Time-dependency of the activation of the early response genes and genes functioning in inflammation, lipid metabolism and cell proliferation and migration, is an important feature of the macrophage differentiation. It was also evident that several novel transcription factors were activated during lipid-loading. It is concluded that cDNA and protein arrays will be useful for the identification of genes that are potential targets for therapeutic interventions.