Genome complexity: role of lncRna's (Introduction)

by David Turell , Friday, April 08, 2016, 16:05 (3152 days ago) @ David Turell

Long non-coding RNA sect1ons of DNA may have an enhancer role for gene activity:-https://www.sciencedaily.com/releases/2016/04/160407150730.htm-"A new genetic clue discovered by a team co-led by a researcher at the Perelman School of Medicine at the University of Pennsylvania is shedding light on the functions of the mysterious "long non-coding RNAs" (lncRNAs). These molecules are transcribed from genes and are often abundant in cells, yet they do not code for proteins. Their functions have been almost entirely unknown--and in recent years have attracted much research and debate.-***-"Some non-protein-coding genes produce small RNA molecules, and many of these have known functions, often in regulating other genes or RNAs. But thousands of our genes produce lncRNAs--defined as being at least 200 nucleotides in length--and their functions remain poorly understood.-"In a study published in 2014, Paralkar and colleagues identified over a thousand distinct lncRNAs in mouse and human blood cells. Most had never been described before. But many turned out to originate from areas of the genome containing known or suspected enhancers--small regions of DNA where transcription factor molecules gather, to stimulate the transcription of nearby genes.-***-"The researchers found strong evidence that in the twisted, looping, double-helix structure of the genome, the promoter end of Lockd DNA comes into direct physical contact with the promoter end of its neighbor Cdkn1b, and in that way acts as an enhancer to stimulate Cdkn1b's transcription.-"Paralkar acknowledged that the Lockd RNA may one day be found to have some other function. "It's impossible to prove absolutely that it has no function--but it seems at least that it has no obvious function in regulating its neighbor Cdkn1b," he said. He emphasized, however, that in determining the function of non-coding DNA and RNA, both DNA-deletion and RNA-blocking experiments--as in this study--are needed to distinguish the function of DNA from its RNA product.-"'One has to decouple the transcript from the DNA," Paralkar said. "Future studies of lncRNA function should adhere to that requirement."-"He added that the discovery of this enhancer function for one example of a lncRNA gene points to the possibility that this is a broadly used mechanism in the genome, found in non-coding and perhaps even some protein-coding genes. Indeed, enhancers are theorized to be one of the key genomic features that distinguishes species such as mice and humans--which share nearly all their protein-coding genes, but relatively few of their enhancers and lncRNA-coding genes.-"'The fact that mice and humans are so different may be due largely to the fact that their genes are being regulated so differently by enhancers, some of which produce RNA molecules that we detect as lncRNAs," Paralkar said."-Comment: Less and less junk DNA. Again a pattern of basic DNA for all animals with modifiers added for different species, simplifying how evolution can be programmed for more complexity as it advances. All fits into my theories.