Cancer Initiation: What is meaning of the word "epigenetics"

Tuesday, January 12, 2016

What is meaning of the word "epigenetics"

 The word epigenetics has become the term of the decade in cancer research, and in some degree, almost all degenerative diseases. Epigenetics appears as though it will fill in missing gaps in developmental diseases as well. It appears now that there is a diverging opinion of that this word actually means.
   At to core of the word, is the well understood base known as genetics. In general terms, genetics refers to the heritable information which is passed from one cell generation to the next cell generation. This heritable information was almost always presumed to be the DNA sequence.
  As the tools of molecular biology have been refined, automated and personalized, it has become apparent the DNA sequence does not account for all of the information passed from each cell generation. In particular, methyl groups can be added to specific sequences in the cells DNA known as CpG islands, where C and G represent nucleotides and p in the connecting phosphate.
   The regulatory region of a cells DNA known as a promoter is typically rich in CpG islands. When these become methylated, a protein known as Methyl CpG Binding protein 2 binds to the promoter, and "epigenetically" blocks expression of that gene.
   A key to the concept of epigenetics is that these methylation patterns are copied upon cell division, the same as DNA sequence. That is, modifications to promoter status are passed from one generation to the next. The prefix "epi" means "on top of" in medical and scientific terminology. Thus DNA methylation is a type of genetics which "piggy backs" on DNA sequence genetics.
  In a recent article in The scientist reviewing RNA methylation, the authors refer to this as "RNA epigenetics".   
   In fact I feel that "RNA modification" or "RNA decoration" would be a better term. There does not seem to be any evidence presented that these modified RNAs can be duplicated and perpetuated from generation to generation. As such, it is not quite in the same class as DNA modifications which are duplicated by a "DNA methyltransferase"


 By Dan Dominissini, Chuan He and Gidi RechaviRNA Epigenetics, The Scientist | January 1, 2016


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