Regulation of gene expression

All the cells of our body contain identical genes.

However, the cells of our muscles look different and fulfill very different functions to, for example, the cells of our eye. So how is this possible? The answer is that not all the ≅20 000 genes are expressed or “switched on” in every cell: specific genes are expressed at specific times in specific cells.

The control of gene expression is highly complex and carefully orchestrated. In this step we will consider three mechanisms which contribute to the regulation of gene expression:

The regulation of protein production

The central dogma describes how DNA encodes RNA which in turn determines the type and order of the constituent amino acids of a protein. Given that it is the different proteins which determine a cell’s characteristics, regulation of protein production, and in particular transcription, is key to the regulation of gene expression.

Epigenetic regulation

The epigenome plays a critical role in the regulation of gene expression both through direct modification of DNA (such as DNA methylation) or through chromatin remodelling.

The production of transcription factors

Transcription factors form complexes and bind to the promoters of genes to initiate transcription. Some components of the transcription complex are always present in cells whilst others are only formed in response to specific stimuli enabling cells to respond to changes in their environment and take on specific/targeted roles.

Gene Expression Diagram © St George’s, University of London

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The Genomics Era: the Future of Genetics in Medicine

St George's, University of London

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