epigenetic
Introduction
In reference to a set of reversible heritable changes in gene function or other cell phenotype that occur without a change in DNA sequence (genotype).
Also see from epigenesis.
These changes may:
- be induced spontaneously
- occur in response to environmental factors
- occur in response to the presence of a particular allele, even if it is absent from subsequent generations.
Epigenetic information takes 3 forms:[6]
- DNA methylation (5-methylcytosine)
- generally associated with gene silencing
- post-translational modifications of histones
- acetylation, methylation, phosphorylation, ubiquitination, sumoylation
- recruitment of transcription factors
- activation of transcriptional enhancers
- recruitment of transcriptional repressors
- interaction with DNA methylation
- higher-order chromatin structure
Cell differentiation is epigenetic, thus a somatic cell can be reprogrammed to become totipotent. Rearrangement of genes in the adaptive immune system represents an exception, because a portion of the DNA has been irreversibly-genetically-deleted from the genome.
Epigenetics includes the study of effects that are inherited from one cell generation to the next, including
- embryonic morphogenesis
- regeneration
- normal turnover of cells, tumors, cell culture
- replication of single celled organisms
Epigenetic inheritance may be maintained through meiosis, & thus may be inherited from one generation to the next in multicellular organisms.
Epigenetic processes include:
- paramutation
- bookmarking
- imprinting
- gene silencing
- X chromosome inactivation
- position effect
- reprogramming
- transvection
- maternal effects
- neoplastic processes
- progression of carcinogenesis
- many effects of teratogens
- regulation of histone modifications & heterochromatin
- technical limitations affecting parthenogenesis & cloning
More general terms
More specific terms
Additional terms
References
- ↑ Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999
- ↑ Wikipedia, the free encyclopedia http://en.wikipedia.org
- ↑ Bell JT, Spector TD. A twin approach to unraveling epigenetics. Trends Genet. 2011 Mar;27(3):116-25. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/21257220
- ↑ Ollikainen M, Craig JM. Epigenetic discordance at imprinting control regions in twins. Epigenomics. 2011 Jun;3(3):295-306. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/22122339
- ↑ Wong CC, Caspi A, Williams B et al A longitudinal study of epigenetic variation in twins. Epigenetics. 2010 Aug 16;5(6):516-26 PMID: https://www.ncbi.nlm.nih.gov/pubmed/20505345
- ↑ 6.0 6.1 6.2 Feinberg AP The Key Role of Epigenetics in Human Disease Prevention and Mitigation. N Engl J Med 2018; 378:1323-1334. April 5, 2018 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/29617578 <Internet> http://www.nejm.org/doi/full/10.1056/NEJMra1402513