Gene may protect against heart disease

Scientists have identified a gene that may play a protective role in preventing heart disease. Their research revealed that the gene, called MeXis, acts within key cells inside clogged arteries to help remove excess cholesterol from blood vessels.

UCLA-led study in mice found that MeXis controls the expression of a protein that pumps cholesterol out of cells in the artery wall. MeXis is an example of a "selfish" gene, one that is presumed to have no function because it does not make a protein product.

However, recent studies have suggested that these so-called "unhelpful" genes can actually perform important biological functions without making proteins and instead producing a special class of molecules called long non-coding RNAs, or lncRNAs.

lncRNAs are important for the inner workings of cells involved in the development of heart disease," said Dr. Peter Tontonoz, senior author of the study. Considering many genes like MeXis have completely unknown functions, the study suggests that further exploring how other long non-coding RNAs act will lead to exciting insights into both normal physiology and disease.

In the study, researchers found that mice lacking MeXis had almost twice as many blockages in their blood vessels compared to mice with normal MeXis levels. In addition, boosting MeXis levels made cells more effective at removing excess cholesterol.
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Effects of long, mysterious strip of RNA on sperm count

Scientists have discovered part of genetic material known as lncRNAs that help sperm develop. Male mice lacking a particular lncRNA have low sperm count, this shows that lncRNAs could represent novel infertility drug targets.

The strands, called long non-coding RNAsor lncRNAs don't seem to encode proteins, but have been implicated in everything from cancer to brain function. Many are located in the testes, suggesting they could contribute to infertility.

Researchers collected and measured lncRNA levels during the process of cellular differentiation that leads to sperm production. They found that specific lncRNAs are associated with each stage of sperm development.

The researchers also identified lncRNAs and mRNAs that are testes-specific -- that is, not found in other human or mouse tissues. Genetically-modified male mice lack one particular lncRNA. They used these mice to assess how the loss of this one lncRNA affects overall mouse fertility.

 Mice provide a model to study human sperm development as the process is highly conserved between the two species. Researchers discovered massive changes in lncRNAs produced in cells that eventually increase mouse sperm. Each stage of sperm development was associated with different lncRNAs. This shows that lncRNAs are important for creating complex biological process.

Many of the lncRNAs were strictly found in mouse testes, a subset of lncRNAs are able to escape gene silencing processes that help turn off unnecessary genes on the X and Y sex chromosomes during sperm development. The X and Y sex chromosomes determine whether a sperm will produce a male or female embryo. lncRNA could serve as a potential therapeutic target for male infertility drugs.
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