Mechanisms of Gene Regulation
Here are three mechanisms of gene regulation:
1. Epigenetic Regulation
2. Transcriptional Regulation
3. Post transcriptional regulation
Epigenetic regulation involves chromatin remodeling. This is a process in which a stretch of DNA sequence is made unavailable for the protein synthesis machinery to act upon, and therefore the corresponding gene is not expressed. This mode of gene regulation has been shown to be prevalent in cancer, where a loss of function of a gene due to epigenetic regulation may trigger cancer development. Histones are responsible for chromatin modifications and they are controlled in turn by DNA methylation.
Transcriptional regulation is very potent method of controlling gene expression by influencing the availability of RNA for protein synthesis. Transcription of DNA by RNA polymerase can be regulated in these ways:
a) Since transcription is a complex process it involves several co-factors called transcription factors whose availability can be regulated, which in turn controls the transcription reaction.
b) There are special repressor molecules available that bind the promoter region of a gene, and therefore make it impossible for RNA polymerase to bind. A classical model of this would be the lac operon.