Gene Regulation: the Control of Gene Expression

Gene expression refers to the production of protein or RNA from the information contained in the gene. This control is referred to as, gene regulation. In this article we review some general concepts about the control of gene expression.

If you are rusty on basic concepts of gene expression, then it is recommended you first read through our primer on this by clicking here. You will need to be familiar with the basic processes of transcription and translation as they pertain to gene expression.

Why would mental health healers be interested in this topic? Glad you asked. The answer is that more and more we are understanding that all healing ultimately takes place at the level of the gene and its expression. If we understand this and what turns gene expression on, off, and in between, then maybe we can find ways to use this knowledge to be more effective healers.

Overview: the water facet

To get an overview of where we are going, let me use a water facet analogy. Let the gene be the water facet and the protein encoded from it, the water. The facet can turned on all the way, in which case the water/protein comes gushing out at full force. The facet can be turned all the way off, in which case no protein/water is coming out. Or the facet can be turned in between.

To understand the control of gene expression, let us start where the scientist did, that is in simple prokaryotes and the lac operon.

Prokaryotes

Gene regulation in prokaryotes (blue-green algae and bacteria; those little guys without distinct nuclei or organelles) is very complicated. The classically studied lac operon in the common intestinal bacteria, E. coli, is an example. "lac" is the abbreviation used for the sugar lactose; the italic form refers to the lactose gene. Operons are clusters of genes that are active in a single metabolic pathway and are controlled by the same promoter. In this case, lactose breakdown into the simpler sugars, glucose and galactose.

A promoter is the binding site of the enzyme, RNA polymerase. This enzyme is the transcription enzyme. It is responsible for transcribing the DNA into messenger RNA (mRNA). For transcription to occur, RNA polymerase must be able to attach itself to the promoter region of the DNA.

What determines whether or how well the RNA polymerase will bind to the promoter? The answer: the metabolic needs of the bacteria and the nutrients available. For example, if no energy is needed, then the cell does not need to waste energy trying to get energy it does not need. Likewise, if no lactose is available, then there is no reason for the cell to crank out lactose digesting enzyme.

All the genes in an operon are transcribed in the same amount at the same time. Now the lac operon only has one gene, the lac gene. But many others in E. coli have several genes in their operon. Example are the arabinose and galactose operons. Both have several genes in their operons.

The importance of multiple genes per operon is that while all the genes in an operon may be transcribed at the same time and in the same amount, they are not all translated the same. Translation, the production of the protein from the mRNA, is under another level of control altogether.

OK, let us now move on to eukarotes, like humans...

Humans and Other Eukaryotes

Things start to get really complicated here. Two additional terms we might take up are up regulation and down regulation. Up regulation refers to something that increases the amount of the genes product (protein and/or RNA). Down regulation refers to something that decreases this. Thus genes can be up regulated or down regulated in eukaryotes.

Regulation in eukaryotes can take place at many more levels than in prokaryotes. This is because eukaryotes are so much more vastly complicated. Some examples,

  • transcription and translation take place in different parts of the cell: within the nucleus for transcription, in the cytoplasm for translation. 
  • The genes are split (see Split Genes for more details) and so the RNA must be processed before it can be translated. Here then is another major control point.
  • Movement of the RNA transcript (mRNA) through the nuclear membrane for translation is another control point.
  • The DNA must be locally unwound so that the RNA polymerase can get to it.
  • There is developmental, circadian, ultradian, reproductive, and aging cycling of gene expression in which batteries of genes are turned on and off, up regulated, down regulated, etc.
  • Even things like touch, social interactions, feelings, expriences, affect gene expression. (Emotions are not something bacteria have to worry about as far as we know.)
  • There are house keeping genes that are responsible for the day to day activities ever cell needs.
  • There are genes that cause cells to be specialized into various cell types and tissues (e.g. muscle, bone, nerve, the various organs, glands, etc.) all of these are under differential control.
  • Mind can affect gene regulation.
For our purposes it is not important to know the complex and various mechanisms involved in all of these. Rather it is important to know how complex gene regulation is in eukaryotes and how healing depends on the right expression of the right genes at the right time and in the right amounts.

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