Transcript Epigenetics
Epigenetics By Katie Van Hove DNA: deoxyribonucleic acid, Double Helix, and it completely and totally defines everyone of our characteristics!!! …Kinda Every cell in the human body has the same DNA, but they definitely don’t all do the same thing. This is because not every gene is expressed in each cell. There are many opportunities to turn off and on a certain gene, and to alter its phenotype, such things like… DNA methylation: the attachment of methylated bases to DNA bases after DNA synthesis almost solely at CpG nucleotides, which regulates and suppresses gene expression and … Histone Acetylation: the attachment of acetyl groups to the proteins around which the DNA is coiled, making gene expression easier. These additions turn the gene expression on and off, silencing some genes and activating others. They do not change the DNA but they can be inherited through epigenetic inheritance. Genomic imprinting- the silencing of one of the parental alleles based on whether it is inherited from the paternal or maternal parent. ●The gene encoding insulin-like growth factor II (IGF2/Igf2) is only expressed from the allele inherited from the father ●The deletion of one of the X chromosomes in women in order to avoid redundancy. Cool, so what does that actually do? During the Dutch Hunger Winter in WWII 30,000 died from famine. From this we learned that prenatal exposure to famine has shown a direct correlation to low birth weight, diabetes, obesity, coronary heart disease, breast and other cancers. Also, low birth weight in the grandchildren, suggesting that how our grandmothers ate when they were carrying our mothers affects our epigenetics at least two generations later Agouti mice have undergone DNA methylation changes by insertion of an IAP element that caused changes in their coat color. Dolly, the first cloned mammal, lived only for seven years. The short lifespan and poor health of cloned animals is due to insufficient reprogramming of epigenetic marks. Two genetically identical agouti mice, one whose mother was fed a diet with folic acid and other methyl-rich supplements during pregnancy and one whose mother has a normal diet. The brown mouse’s agouti gene has been shut off, whereas her genetically identical sister is yellow and has a higher rate of obesity, diabetes, and cancer. Giving a pregnant mouse supplemental choline (C5H14N+O), (found in milk, eggs, beef nuts, fish) a B complex vitamin, shows increased mental activity and intelligence in the offspring. The mice whose mother received the supplemental diet during late pregnancy had larger neurons with more dendrites then those whose mother was fed the regular diet. “Choline has been shown to activate two hippocampal proteins shown to contribute to learning and memory” (Williams and Meck in collaboration with J.K. Blusztajn). Supplementing a women’s diet with folic acid before and during the pregnancy have shown to reduce the risk of a neural tube defect by 70%. Monozygotic (identical) twins look different. they have the same genes, but they have different epigenetics. Cancer Hypomethylation or hypermethylation (too little or too much) can cause the activation of oncogenes (a gene that causes the transformation of normal cells to tumorous cancer cells) and/or the silencing of tumor suppressor genes. This, along with genetic abnormalities contributes to the formation of cancer cells. It only takes two of these LOH (loss of heterozygosity), Deletion, Mutation (genetic causes), or DNA methylation (epigenetic) for the cancer gene to become inactive. The hypermethylation can be used as a marker of cancer cells because the hypermethylation of the tumor suppresser genes only happens in cancerous cells. Also, an epigenetic cause gives hope, because epigenetics are reversible. If one could find the correct demethylating agent, the genes silenced by methylation could be re-expressed. ●Vidaza is one such drug. It has shown considerable antitumoral activity and has been approved for treatment of the pre-leukemic disease myelodysplastic syndrome. Epigenetics is a whole new field of exploration and discovery that shows promise in helping find treatments and cures for all disease, like cancer, lymphoma, and leukemia. With more research we can unlock the delicate nature of our cells, and who we are. Bibliography Agouti mice. Dukemednews.duke.edu. 4/20/07. www.dukemednews.org/.../detail.php&id=1125 Esteller, Manel. “The necessity of a human epigenome project.” Carcinogenesis, May 2006. Pg.1121–1125 Fairley, Peter. “Epigenetics” Technology Review; Mar/Apr 2006. P59-61, Hugh D. Morgan, Heidi G.E. Sutherland, David I.K. Martin & Emma Whitelaw. “Epigenetic inheritance at the agouti locus in the mouse” Nature Genetics 23. 1999. pg. 314 - 318 “Maternal Diet Interacts with Genome for Better...and Maybe Worse.” Genomelife. May 2004. Moshe, Szyf. “Article Learning without learning reports on the research” The Economist © 20069/23/2006, Vol. 380 Issue 8496, p89-90, 2p, 1c Pray, Leslie A. “Epigenetics: Genome, Meet Your Environment.” The Scientist, July, 2004. Plass, Christoph. “Cancer epigenomics.” Human molecular genetics, June 2002. pg 24792488 Qui, Jane. “Epigenetics unfinished symphony.” Nature, May 2006. “The human epigenome.” Economist. 12/24/2005, Vol. 377 p108-108. www.dictionary.com www.wikipedia.com Campbell and Reece. Biology 7th edition.