#noncoding rna

'Junk' DNA now center stage

The classes of RNA molecules encoded by DNA sequences previously considered non functional may play a vital role in cell stress responses, and could one day lead to cancer treatments. A*STAR researchers have identified a class of the long non-coding RNAs responding upon oxidation stress and characterized and specified their functions across stress stimuli and cell types. 

Human skin and lung cells were subjected to oxidative stress, by the research team, stimulating cellular pathways of repair and survival. While protein-coding genes were generally inhibited, stress caused noncoding genomic regions to produce thousands of RNA molecules called 'long noncoding RNAs (lncRNAs)'.

Author Igor Kurochkin says the role of lncRNAs is a mystery. "We don't know their function, or even if they function at all." They may act in the evolution of new genes; in helping cells respond to stress; in interaction with genes or proteins; or, says another author, Vladimir Kuznetsov, "all of these at once!"

Antonis Giannakakis et al. Contrasting expression patterns of coding and noncoding parts of the human genome upon oxidative stress, Scientific Reports (2015). DOI: 10.1038/srep09737

Scientists discover a new role for RNA in safeguarding human chromosome number

Molecular biologists at UT Southwestern Medical Center have identified a gene called NORAD that helps maintain the proper number of chromosomes in cells, and that when inactivated, causes the number of chromosomes in a cell to become unstable, a key feature of cancer cells.                                

Previously, genes that encode the recipe for making proteins have been implicated in maintaining the proper number of chromosomes in a cell. The NORAD gene, however, does not encode a protein. Instead, NORAD produces a long noncoding RNA, a type of molecule that was not previously known to be important in chromosome maintenance, the researchers report in the journal Cell.

"In the absence of the NORAD RNA, the number of chromosomes in cells becomes highly abnormal," explained Dr. Joshua Mendell, Professor of Molecular Biology at UT Southwestern and a Howard Hughes Medical Institute Investigator. "This is an entirely new function for a noncoding RNA and may have implications in cancer biology since genomic instability is a hallmark of tumor cells."

Researchers began studying this particular molecule because the RNA kicks into action after DNA is damaged; they therefore termed it Noncoding RNA Activated by DNA Damage, or NORAD.

Exogenous microRNAs in maternal food pass through placenta, regulate fetal gene expression

In a new study published in the Protein & Cell, Chen-Yu Zhang's group at Nanjing University reports that small non-coding RNAs in maternal food can transfer through placenta to regulate fetal gene expression.

MicroRNAs (miRNA) are a class of noncoding RNAs with lengths of approximately 22 nucleotides that bind to target messenger RNAs to inhibit protein translation. In previous studies, the same group has found that plant miRNAs can enter into the host blood and tissues via the route of food-intake. The food-derived exogenous miRNAs are absorbed, packaged into microvesical (MV) and then secreted into circulation by cells of animal GI tract. More importantly, once inside the host, the food-derived exogenous miRNAs can regulate host physiology by regulating host "target" genes in the cross-kingdom manner. In support of this new concept, they have also found a plant microRNA, MIR2911, which is enriched in honeysuckle, directly targets influenza A viruses (IAV) including H1N1, H5N1 and H7N9. Drinking of honeysuckle soup can prevent IAV infection and reduce H5N1-induced mice death.

Here, they report another surprising finding that exogenous plant miRNAs and artificial synthetic small influence RNAs (siRNAs) can transfer through the placenta and directly regulate fetus gene expression.