15 May 2008

Small RNA Gene Regulation

The class of RNA known as "small RNA"--a subset of "non-coding RNAs"--is growing larger. Scientists are also growing more aware of the importance of this once obscure class of molecules, that apparently plays a critical role in regulating gene expression.
...molecular biologists have increasingly realized that many RNA snippets -- so-called small RNAs -- also directly influence which genes make proteins, and in some cases, how much protein. They've also found that some small RNAs play a unique role in protecting the integrity of genetic material.

..."It turns out that there are more types of small RNA molecules than anyone initially suspected," said Gregory J. Hannon, Ph.D., CSHL professor and pioneer in small RNA research. "And we are finding that each type that we discover acts in more ways than had previously been appreciated."

...Dr. Hannon and his collaborators are harnessing highly efficient new machines that determine the sequence of bases in millions of small RNA molecules simultaneously. They then scan the known genome to find matching sequences, as well as the sequences nearby. This original context is crucial to understanding why some snippets are chosen as regulators.

...Many RNA sequences, such as microRNAs, are flagged as regulatory molecules because they physically fold on themselves. Special proteins recognize the resulting double-stranded RNA, and chemically slice it to release regulatory RNA snippets.

The CSHL team found that double-stranded structures also form from "pseudogenes." Pseudogenes, in the past assumed to be useless "junk DNA," are damaged copies of normal genes left over from previous genetic events. The researchers found that RNA copies of normal genes sometimes pair up with copies from the related pseudogenes, resulting in double-stranded RNAs that -- far from being junk -- are able to activate the cell's regulatory apparatus. __ScienceDaily
The complexity of the small RNA systems of gene regulation is coming as something of a surprise to many biologists. These RNAs are part of a complex adaptive system which monitors and modifies gene expression according to rules that are so far poorly defined. As scientists utilise the increasingly powerful tools of systems biology, the long-held secrets of evolution on Earth are being teased out of the tangle.

It is no accident that the explosion of knowledge about genetic systems and control is occurring at the same time as the explosion of knowledge within information systems, and within systems in general. Without the micro-arrays, the sequencing tools, the computational hardware and software of bio-informatics, this work would be infinitely harder.

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