MAR 22, 2017 03:28 PM PDT

Transcription Mechanism Sheds new Light on Junk DNA

WRITTEN BY: Carmen Leitch

Researchers have discovered a mechanism used by a unicellular organism that turns so-called junk DNA into meaningful genetic material that gets transcribed prior to degradation. Genetic research has largely focused on genes that hold the instructions for building proteins, but the vast majority of our genome, and the genomes of other species, contains large regions whose function is unknown, and does not code for protein, which earned it the dubious distinction as junk DNA. It has been suspected by many that these regions are functional, however, and the technique that the unicellular organism uses to make sense of its junk is quite clever. Along with their publication in Cell reporting their findings, the researchers from the University of Bern present a video abstract of their work.

The researchers have found that small pieces of RNA get stitched together into a loop. The investigators were interested in the unicellular ciliate, Paramecium tetraurelia, because they identified small RNA molecules that excise pieces of Paramecium DNA. Looking deeper, there was a kind of feedback loop operating in the excision of DNA segments. Junk DNA was being cut out of the genome, and it is then transcribed into RNA before getting degraded by cellular machinery. The transcribed RNAs act to help cut out even more DNA, building up the RNA production from these excised pieces. However, the resulting RNA pieces are quite small; they are too tiny to be read by normal cellular machinery. 

The scientists had to keep digging to learn more about what as happening. "It was an interesting detective work," Nowacki remembers. They had a suspect -- all they needed was to pin it down. "We were not actually looking for the unknown, because we soon had an idea, and then it was all about testing that idea." What they found was that the RNAs were strung together, into strands or concatemers that are about 200 base pairs long and then closed into a loop.

The evidence continues to mount that so-called junk DNA has important functions, likely in the regulation of gene expression and who knows what else. Nowacki suggested that this is the first time, a precise mechanism has been identified whereby deleted, junk DNA is transcribed. That could mean it will finally shed its junky nickname.

Nowacki's lab is working on the NCCR "RNA & Disease -- The Role of RNA Biology in Disease Mechanisms" project, which aims to reveal more about the role of RNA in disease. RNA is a crucial part of gene expression, and disruptions in that system have been linked to cancer, diseases of the heart and brain, and metabolic disorders. Swiss researchers that study different aspects of the function and characteristics of RNA work together at the NCCR, coordinating research using a variety of models like plants, yeast, roundworms, mice and human cells.

Transcription from ultra-short deleted DNA segments is made possible by their concatenation and circularisation. Excised DNA segments are represented by pieces of train track. The RNA polymerase, represented by the train engine, can only proceed when segments are joined together. / Credit: Sophie R. Allen, ICB, University of Bern

 

Sources: Phys.org via University of Bern, Cell

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAR 16, 2019
Cardiology
MAR 16, 2019
The Discovery That Changed Burn Care Forever
Material scientist Ioannis V. Yannas has made many significant contributions to science. Of these, he likely considers one lifesaving discovery to be his c...
MAR 25, 2019
Drug Discovery
MAR 25, 2019
Discovery of Biomarker Target for Melanoma
According to a study published in the journal Cancer Research, researchers have discovered a biomarker that could serve as a possible therapeutic target fo...
APR 04, 2019
Cell & Molecular Biology
APR 04, 2019
A Newly Identified Function of Ancient Cellular Machinery
Once thought to only function in cell division, scientists have revealed a new role for cellular machinery in the development of the nervous system....
MAR 28, 2019
Cell & Molecular Biology
MAR 28, 2019
Researchers Find a Way to Diagnose Fibromyalgia
The CDC has estimated that about four million adults in the US suffer from fibromyalgia, and many are undiagnosed....
MAY 15, 2019
Genetics & Genomics
MAY 15, 2019
Polygenic Score Can Predict Obesity Risk
  How does the test work?  How was it developed?  What does the test tell us?  Researchers have developed a genetic screening that will...
MAY 16, 2019
Cell & Molecular Biology
MAY 16, 2019
Scientists Create Artificial Life with a Synthetic Genome
In a short period of time, researchers were able to engineer an artificial form of microbial life, using relatively simple techniques....
Loading Comments...