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item Richards, Mark

Submitted to: Medical Biomethods Handbook
Publication Type: Review Article
Publication Acceptance Date: 12/15/2003
Publication Date: 10/1/2004
Citation: Richards, M.P. 2005. Techniques for gene expression profiling. In: Medical Biomthods Handbook., Totowa, New Jersey: Humana Press. Walker, J.M., Rapley, R., eds. p. 505-516.

Interpretive Summary: Within the past several years, the entire complement of genes (genome) of human beings and a number of other important organisms such a yeast and mouse have been completely decoded (sequenced). The genetic code for these and a growing list of species is now becoming available to researchers for further study. However, to be able to utilize and derive benefits from this information, it is necessary to be able to identify all of the individual genes and to understand the function(s) of each. This process, called functional genomics, seeks to understand gene structure, gene activity (also called gene expression) and the ultimate products of genes, proteins. Proteins have been called the molecular machines of life because they do all of the work within cells. Thus, it is important to study DNA, RNA and protein in order to understand the full spectrum of gene activity. This review describes some strategies and technologies utilized by researchers to study gene structure and function by studying gene sequence, gene expression and the proteins produced by the genes. By integrating all of the information obtained by these endeavors, it is expected that scientists will better be able to understand life at the molecular level. Such understanding can then be applied to solve medical, nutritional, genetic and environmental problems occurring in human and animal species.

Technical Abstract: Now that the human genome and the genomes of a growing number of important model eukaryotic organisms such as yeast and mouse have been sequenced, research emphasis in the 'post-genomic' era is beginning to shift to events downstream of the whole genome. Interest is now focused on the identification and characterization of individual genes and gene networks to better understand gene function at the cell, tissue and organ levels in different states of health and disease. This new approach to studying the genome has been named 'functional genomics' because efforts are directed toward understanding the connections between the expression of individual genes or groups of genes and their unique biological functions. Although every cell in the body contains the same complement of genetic material, each is distinguished by the level and the spectrum of activation or expression of a specific set of genes. Determining which genes are active in different cells and tissues under different conditions (i.e., physiological, developmental, environmental, stress, disease, etc.) aids researchers in understanding cellular and tissue function at the molecular level. Thus, it is important to develop and apply a variety of techniques that can accurately measure gene structure and gene activity at the level of DNA, RNA and protein. This review presents an overview of some approaches that have been taken to profile gene expression at the mRNA and protein levels.