Regulation of gene expression

Regulation of gene expression refers to the cellular control of the amount and timing of appearance of the functional product of a gene. The performance (expression) of genes is measured by the amount of gene product (the biochemical material, either RNA or protein) that is synthesized. Gene regulation is essential for cells to respond to changes in their environment and to undergo cell division, differentiation, and morphogenesis.

Overview

Gene expression is the process by which the genetic code - the nucleotide sequence - of a gene is used in the synthesis of a functional gene product. It involves the production of a molecule of messenger RNA (mRNA) that is a copy of the gene, which is then translated into a protein. Regulation of gene expression includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products.

Mechanisms of Gene Regulation

Gene regulation can occur at any point during gene expression, but most commonly occurs at the level of transcription (when the information in a strand of DNA is copied into a new molecule of mRNA). This is achieved by the action of transcription factors which bind to specific DNA sequences, enhancing or hindering the enzyme RNA polymerase in its transcription of the genetic code into mRNA.

Transcriptional Regulation

Transcriptional regulation is the most common form of regulation, and is the first stage at which gene expression can be controlled. It involves the binding of transcription factors to promoter sequences in the DNA, which can either enhance or inhibit the transcription of the associated gene.

Post-transcriptional Regulation

Post-transcriptional regulation occurs after the mRNA has been produced. It can involve the modification of the mRNA, such as the addition of a poly-A tail and a 5' cap, which are necessary for the mRNA to be translated. It can also involve the control of the rate at which the mRNA is translated into protein, or the rate at which the mRNA is degraded.

Role in Development and Disease

Regulation of gene expression is crucial for the development and function of all organisms. It allows cells to adapt to changes in their environment, to grow and divide, and to differentiate into specialized cell types. Disruptions in gene regulation can lead to diseases such as cancer, autoimmune diseases, and neurodegenerative diseases.

See Also

• Epigenetics
• Gene silencing
• Operon
• Transcription factor