Epigenetic Inheritance: Inheritance by Histones

Contrary to popular belief, all biological traits are not just inherited by DNA, but also other materials present in cells which are called epigenetic information play a major role in inheritance1. Epigenetic memory is the transformation of epigenetic information which includes DNA methylation, histone modifications, and small RNA changes during cell division2. In this review, we focus on histone modifications.

Histones are proteins that are the main components of chromatin that makeup DNA and chromosome3. Histone proteins do not only provide structural support but also determine whether DNA transcription will occur3. Consequently, histone modifications can be a determinant of both active and inactive regions of chromatin.

There are various types of histone modifications including, methylation, acetylation, and phosphorylation which are associated with different cellular functions like transcription, DNA replication, and nucleosome compaction4. As a result of this post-translational modification act in many biological processes, ıt can impact gene expression by altering chromatin structure5.

Figure 1: Structure of histone.

There are numerous studies conducted on H2A, H2B, H3, and H4, some of the histone variants being the most extensively studied histones6. One of these studies, It is found that the histone H3 variant has cooperated with the determination of epigenetic memory of an active gene state in Xenopus (amphibian) nuclear-transplanted embryos4.

In another research published in Science in 2015, scientists introduced changes to a histone protein of a yeast cell, causing it to turn off nearby genes, and observed that it was passed through generations of yeast cells1. After the research was published, Professor Robin Allshire, who carried out the study, said: “Our finding settles the idea that inherited traits can be epigenetic, meaning that they are not solely down to changes in a gene’s DNA.”

Figure 2: Structure of histone.

As a result, the inheritance of the epigenetic memory from one generation to subsequent generations is crucial for the preservation of a cell differentiation state. Hence, it is very clear that histones one of the materials which make up the structure of our DNA and chromosomes are very important for inheritance at least as much as our genes.

References:

  1. Sciencedaily.com, DNA can’t explain all inherited biological traits, research shows, www.sciencedaily.com/releases/2015/04/150402161751.htm Alınma tarihi: 06.01.2021
  2. Migicovsky Z.,Kovalchuck I.( 08 June 2011). Epigenetic memory in mammals. https://www.frontiersin.org/articles/10.3389/fgene.2011.00028/full#B6 Alınma tarihi: 06.01.2021
  3. https://www.genome.gov/genetics-glossary/histone
  4. Ray K. Ng & John B. Gurdon (2008) Epigenetic inheritance of cell differentiation status, Cell Cycle, 7:9, 1173-1177, DOI: 10.4161/cc.7.9.5791 Alınma tarihi: 07.01.2021
  5.  Bannister A., Kouzarides T., (15 February 2011) Regulation of chromatin by histone modifications, 381–395 Alınma tarihi: 07.01.2021
  6.  Shi Y., Greer E., Histone methylation: a dynamic mark in health, disease and inheritance. 13(5): 343-357 Alınma tarihi: 07.01.2021

Figure Referances:

  1. https://www.genome.gov/genetics-glossary/histone
  2. https://www.whatisepigenetics.com/histone-modifications/

Inspector: İrem ÖĞÜTÜCÜ

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