By Dr Ananya Mandal, MD
Gene expression is one of the most tightly controlled processes in the body. This process needs to be strictly regulated to ensure that cells produce the correct amount of proteins when they need them. Any disruption to this regulation can lead to serious consequences, including cancer.
Gene expression is regulated according to the needs of the cells. If the cell is exposed to an environment where particular gene products are needed, the expression of that gene product will be increased. Cells also produce specific gene products in response to external signals or cellular damage.
Two examples of gene expression regulation include the control of insulin expression to ensure blood glucose levels are regulated and the control of cyclin expression to ensure normal progression of the cell cycle. In this way, gene regulation determines the cell’s overall structure and function, governing cell differentiation, cell morphology and the cell’s adaptability to its environment.
Gene expression is regulated at different stages. For example, the transcription step may be prevented to stop DNA being converted to RNA or the post-translational modification of a protein may be stopped.
Transcription may be regulated in three main ways, as follows:
- Genetic – Where a control factor interacts with the gene
- Modulation – Where a control factor interacts with the transcription machinery
- Epigenetic – Where non-sequence changes in DNA structure affect transcription
Regulation at the post-transcriptional stage is controlled by importin and exportin proteins that influence the transport of RNA in and out of the nucleus.
Regulation at the translation stage is less common than at other stages. This form of regulation is used by antibiotics and toxins, for example, which inhibit protein translation in order to disrupt the cell’s usual gene expression, therefore leading to cellular dysfunction and death.
Reviewed by Sally Robertson, BSc
Last Updated: Jun 24, 2014