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Vol. LXVI, No. 1
January 3, 2014
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Digest

Study Breaks Blood-Brain Barriers to Understanding Alzheimer’s

A study in mice shows how a breakdown of the brain’s blood vessels may amplify or cause problems associated with Alzheimer’s disease. The results suggest that blood vessel cells called pericytes may provide novel targets for treatments and diagnoses.

A study in mice shows how a breakdown of the brain’s blood vessels may amplify or cause problems associated with Alzheimer’s disease. The results suggest that blood vessel cells called pericytes may provide novel targets for treatments and diagnoses.

A study in mice shows how a breakdown of the brain’s blood vessels may amplify or cause problems associated with Alzheimer’s disease. The results, published in Nature Communications, suggest that blood vessel cells called pericytes may provide novel targets for treatments and diagnoses. The study was co-funded by the National Institute of Neurological Diseases and Stroke and the National Institute on Aging.

Alzheimer’s disease is the leading cause of dementia. Brains from Alzheimer’s patients typically have abnormally high levels of plaques made up of accumulations of beta-amyloid protein next to brain cells, tau protein that clumps together to form neurofibrillary tangles inside neurons, and extensive neuron loss.

Vascular dementias, the second leading cause of dementia, are a diverse group of brain disorders caused by a range of blood vessel problems. Brains from Alzheimer’s patients often show evidence of vascular disease, including ischemic stroke, small hemorrhages and diffuse white matter disease, plus a buildup of beta-amyloid protein in vessel walls.

In this study, researchers show that pericytes may be a key to whether increased beta-amyloid leads to tangles and neuron loss.

Pericytes are cells that surround the outside of blood vessels. Many are found in a brain plumbing system called the blood-brain barrier. It is a network that exquisitely controls the movement of cells and molecules between the blood and the interstitial fluid that surrounds the brain’s nerve cells.

Gene-Silencing Data Now Publicly Available

For the first time, large-scale information on the biochemical makeup of small interfering RNA (siRNA) molecules is available publicly. These molecules are used in research to help scientists better understand how genes function in disease. Making these data accessible to researchers worldwide increases the potential of finding new treatments for patients.

The National Center for Advancing Translational Sciences collaborated with Life Technologies Corp. of Carlsbad, Calif., which owns the siRNA information, to make it available to all researchers.

The siRNA molecules, which can selectively inhibit the activity of genes, are used in RNA interference (RNAi) research. RNAi is a natural process that cells use to control the activity of specific genes.

Scientists have harnessed the power of RNAi to study the function of many individual genes by reducing their activity levels or silencing them. This process enables researchers to identify genes and molecules that are linked to particular diseases. To do this, researchers use siRNAs, which are RNA molecules that have a complementary chemical makeup, or sequence, to that of a targeted gene. While the gene is silenced, researchers look for changes in cell functions to gain insights about what it normally does. By silencing genes in the cell one at a time, scientists can explore and understand their complex relation to other genes in the context of disease.

NCATS and Life Technologies are providing all researchers with access to siRNA data from Life Technologies’ Silencer Select siRNA library, which includes 65,000 siRNA sequences targeting more than 20,000 human genes. Simultaneously, NCATS is releasing complementary data on the effects of each siRNA molecule on biological functions. All of this information is available to the public free-of-charge through NIH’s public database PubChem.

Aquatic Comb Jelly Floats into New Evolutionary Position

In a study that compares the genomes of aquatic life forms, researchers have found evidence to shuffle the branches of the tree of life. For more than a century, scientists thought that complex cell types, like neurons and muscles, evolved only once, after simple animals that lack these cell types branched from the rest of animals on the evolutionary tree. A team of researchers from the National Human Genome Research Institute has provided new evidence from the genomic study of a ctenophore species—a comb jelly—that challenges this long-held view.

The cornerstone of the study, published in the Dec. 13 online issue of Science, is the researchers’ sequencing, assembly, annotation and analysis of the genome of Mnemiopsis leidyi, a comb jelly native to the coastal waters of the western Atlantic Ocean. Whole-genome sequencing data shows that comb jellies branched from the rest of the animals before the sponge, a simple animal without complex cell types, according to the study. —compiled by Carla Garnett


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