What is Gene Regulation?
Have you all ever been amazed at how our body makes different types of cells and how those cells perform different functions?
Generally, our body is made up of hundred types of cells which are different in their forms and vary with their functions, accounting from our skin to our immune and blood cells.
All these cells contain the same genetic material, ie. DNA but these cells vary in their structure and function, because of gene regulation.
Gene regulation is one of the processes in which the genes are turned on and off. During the early development of an organism, the cells beings to take up specific mechanisms.
The Gene regulation process helps in ensuring, whether the genes are expressed in an appropriate manner and at a proper time.
Gene regulation helps an organism to respond to environmental conditions.
Gene regulation is activated by various mechanisms like modification of genes chemically, use of regulatory proteins to switch on and off the genes, etc.
The human genome consists of almost 20,000 genes. Out of which 10, 000 are actively present in the cells, and the remaining 10,000 will be in an inactivated form.
Such that the cell determines which gene will be active and which will not be activated, ie. In the inactive form.
Gene Regulation Features
Gene regulation is a mechanism that controls the genes by activating a few of them out of the many genes that are present in its genomes.
Gene regulation is very much important as each cell in our body has a different set of genes, interestingly, all cells in our body have the same DNA, but these differ in their expression of the genes, causes variations among them and each of the cells has a different set of proteins which makes them unique in their function.
One such example of gene regulation is the functioning of the liver. The function of the liver is to remove the toxic substances that are present in our body such as alcohol and chemical agents in our bloodstream that we intake through some kinds of food substances.
To make the liver function, liver cells express a gene encoding subunits in an enzyme which is known as alcohol dehydrogenase.
This enzyme breaks the alcohol into a non-toxic molar substance. Then the neurons in the brain get activated and send particular signals to remove the toxins from the body of an individual, at this time the genes are unexpressed, which means that they are turned off, in the same way when the genes of the liver cells are in functions, the genes of the neurotransmitters are turned off.
How Does Gene Regulation Work?
As mentioned above, different cells express different types of gene regulations. In some cases, two different types of cells of the same kind have different types of expressions based on environmental conditions.
However, the gene expression pattern is determined from both inside and outside the cell. Where the example that can be sorted for gene expression from inside a cell is the inheritance of proteins from its mother cell in case of any damage in the DNA and the amount of ATP it has.
The example that can be sorted for gene expression from outside the cell is that the chemical signals which are arising from the other cells in the form of mechanical signals from the extracellular matrix and the nutrient levels in the cells.
How Do Cells Control Gene Regulation?
First of all, cells do not make decisions that, which cell has to generate an expression. Instead of the cells, undergoes molecular pathways which help them to converts the information in such a way that it binds to its specific receptors with the help of a chemical signal that is generated as a result of gene expression.
Let us consider an example of how cells react to the growth factors. The growth factor is one of a chemical signal which arises from a neighboring cell to instruct a target cell to grow and divide.
This process occurs in such a way that the cell detects the growth factor by binding to the growth factor physically which is present on a cell surface as a receptor protein.
Such binding of a growth factor causes the receptors to change their shape, by triggering a series of chemical events in a cell that activates proteins, and it is known as transcription factors.
Further, these transcription factors bind to a certain sequence of the DNA that is present inside a nucleus and causes transcription of the genes to activate cell division.
As a result, the genes which is the product of different proteins make the cells divide and induce growth in a cell.
Eukaryotic Gene Regulation
Gene regulation is a result of various kinds of expressions in a gene. Let us discuss how the genes are being expressed in various stages depending on the availability of the DNA to produce the mRNAs which help in translating and processing the respective proteins.
This Eukaryotic gene expression involves many steps and all these can be regulated. Different genes are being regulated at different intervals.
The expression of eukaryotic genes involves many factors such as follows.
I. Chromatin Accessibility
The structure of chromatin is very much important for the regulation of the genes as the more open or relaxed the chromatin makes the gene more available for transcription.
Transcription acts as a key for the regulation of many genes. A set of transcription factors helps a protein to bind with a specific sequence of DNA in or near a gene which either promotes or represses a transcription into an RNA.
III. RNA Processing
RNA processing involves splicing, capping, and an addition of a poly-A tail to regulate a molecule of RNA. Various mRNAs are made from the same pre-RNA by the process of alternative splicing.
IV. RNA Stability
The lifetime of an mRNA molecule in a cytosol affects many proteins which are made from it. Many of the small regulatory RNAs can bind to the target mRNAs which causes them to chopped up Whereas the small regulatory RNAs are called miRNAs.
Translation of an mRNA can be increased by the regulators. Protein activity: Proteins undergo a variety of modifications, which are being chopped up or tagged with the chemical groups.
These modifications can be regulated which also affects the activity or behavior of the proteins.
Although all the stages of gene expression are regulated, the main control activity of the gene is transcription.
Further process of gene regulation refines the patterns of gene expression that are roughed out during transcription.
Gene Regulation Citations
- RNA-RNA interactions in gene regulation: the coding and noncoding players. Trends Biochem Sci . 2015 May;40(5):248-56.
- The Evolution of Gene Expression in cis and trans. Trends Genet . 2018 Jul;34(7):532-544.
- Enhancer DNA methylation: implications for gene regulation. Essays Biochem . 2019 Dec 20;63(6):707-715.
- Gene Regulation in and out of Equilibrium. Annu Rev Biophys . 2020 May 6;49:199-226.
- Epigenetic regulation and chromatin remodeling in learning and memory. Exp Mol Med . 2017 Jan 13;49(1):e281.
- Building Transcription Factor Binding Site Models to Understand Gene Regulation in Plants. Mol Plant . 2019 Jun 3;12(6):743-763.
- Crossroads between transposons and gene regulation. Philos Trans R Soc Lond B Biol Sci . 2020 Mar 30;375(1795):20190330.
- Fighting the Fire: Mechanisms of Inflammatory Gene Regulation by the Glucocorticoid Receptor. Front Immunol . 2019 Aug 7;10:1859.
- The role of 3D chromatin domains in gene regulation: a multi-facetted view on genome organization. Curr Opin Genet Dev . 2020 Apr;61:1-8.