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Polymorphism in non-coding region affects expression of the innate immune defense gene IFIH1 in the bank vole (Myodes glareolus)

Szücs, Ilona (2018) BIOK01 20181
Degree Projects in Biology
Popular Abstract
Genetic variation in an immune defense gene

The immune system is one of the barriers to the external world, and the multiple types of microbes that could be dangerous to our health. In the part of our immune system that we normally call the innate immune system, we have different sensors for these various types of microbes. The sensors are found inside some of the cells of mammals or on the surface of the cell. They help the body to detect intruding viruses and bacteria that can cause us harm. One of these sensors are called MDA5 and can sense viruses that has entered the cell. MDA5 is encoded by a gene called IFIH1 which has shown to have large genetic variation in the form of polymorphism in earlier studies done on both human and bank... (More)
Genetic variation in an immune defense gene

The immune system is one of the barriers to the external world, and the multiple types of microbes that could be dangerous to our health. In the part of our immune system that we normally call the innate immune system, we have different sensors for these various types of microbes. The sensors are found inside some of the cells of mammals or on the surface of the cell. They help the body to detect intruding viruses and bacteria that can cause us harm. One of these sensors are called MDA5 and can sense viruses that has entered the cell. MDA5 is encoded by a gene called IFIH1 which has shown to have large genetic variation in the form of polymorphism in earlier studies done on both human and bank vole.

Genetic variation can take many shapes and forms, but the ones found in IFIH1 are Single-Nucleotide Polymorphisms, also called SNPs. SNPs occur when mutations in the DNA changes one nucleotide to another. The introduction of SNPs into DNA happens all the time and can in some cases lead to areas of the DNA having a large quantity of these. SNPs will often be inherited together in a pattern, and different individuals can carry different variants. In the case of human IFIH1 the SNPs are found inside the protein-coding part of the gene. This means that the SNPs can change the amino acid sequence which in turn can result in a changed MDA5 sensor. In humans some variants have been linked to both a higher immune defense against viruses, but at the same time shown a risk for developing autoimmune diseases such as type 1 diabetes. In comparison with the human IFIH1, the bank vole IFIH1 does not carry polymorphism in protein-coding parts but in the non-coding DNA that surround these parts. Non-coding parts of the DNA can sometimes help to regulate the expression of the gene by allowing the gene to be transcribed more or less.

In this project the genetic variation in the non-coding parts of 39 bank vole’s IFIH1 was sequenced and investigated in more detail. The different bank vole individuals were assigned a genotype regarding what patterns of SNPs they had. These genotypes were then tested to see if they had any differences in gene expression.

In earlier studies the genetic variation that was found showed only SNPs but, in this study, indels were also found. Indels are either insertions or deletions of nucleotides, but it can be hard to tell which of the two, so they are collectively called indel. Overall the polymorphisms matched the ones found in earlier studies. There was a significant difference in gene expression between the different genotypes. Whether the difference in gene expression is connected to a higher resistance to viruses as in humans is not possible to say now since a higher or lower gene expression would not necessarily be connected to a higher resistance. In humans the genetic variation is conserved in the population by a trade-off between higher resistance to viruses and autoimmunity. This could be the case for the bank vole as well but now there is no possibility to know. However, in the future it would be possible to conduct a project which could show if gene expression and resistance were connected.

Examensarbete för kandidatexamen i Biologi 15 hp 2018
Biologiska institutionen, Lunds Universitet

Handledare: Lars Råberg
Funktionell zoologi (Less)
Please use this url to cite or link to this publication:
author
Szücs, Ilona
supervisor
organization
course
BIOK01 20181
year
type
M2 - Bachelor Degree
subject
language
English
id
8962390
date added to LUP
2018-10-25 16:15:34
date last changed
2018-10-25 16:15:34
@misc{8962390,
  author       = {{Szücs, Ilona}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Polymorphism in non-coding region affects expression of the innate immune defense gene IFIH1 in the bank vole (Myodes glareolus)}},
  year         = {{2018}},
}