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Vol. LXV, No. 23
November 8, 2013
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Digest

Tanning Gene Linked to Increased Risk of Testicular

A gene important in skin tanning has been linked to higher risk for testicular cancer in white men, according to a study led by scientists from NIH and the University of Oxford in England. Nearly 80 percent of white men carry a variant form of this gene, which increased risk of testicular cancer up to threefold in the study.

The research appeared online Oct. 10 in the journal Cell and is the result of an integrated analysis of so-called big data supported by laboratory research. The team suspected that variations in a gene pathway controlled by the tumor suppressor gene p53 could have both positive and negative effects on human health.

“Gene variations occur naturally and may become common in a population if they convey a health benefit,” said Dr. Douglas Bell, an author on the paper and researcher at the National Institute of Environmental Health Sciences. “It appears that this particular variant could help protect light-skinned individuals from UV skin damage, like burning or cancer, by promoting the tanning process, but it permits testicular stem cells to grow in the presence of DNA damage, when they are supposed to stop growing.”

Bell explained that p53 stimulates skin tanning when ultraviolet light activates it in the skin. It then must bind a specific sequence of DNA located in a gene called the KIT ligand oncogene, which stimulates melanocyte production, causing the skin to tan.

Brain May Flush Out Toxins During Sleep

Researchers showed for the first time that the space between brain cells may increase during sleep, allowing the brain to flush out toxins that build up during waking hours. The study was funded by NINDS.

Researchers showed for the first time that the space between brain cells may increase during sleep, allowing the brain to flush out toxins that build up during waking hours. The study was funded by NINDS.

A good night’s rest may literally clear the mind. Using mice, researchers showed for the first time that the space between brain cells may increase during sleep, allowing the brain to flush out toxins that build up during waking hours. These results suggest a new role for sleep in health and disease. The study was funded by the National Institute of Neurological Disorders and Stroke.

“Sleep changes the cellular structure of the brain. It appears to be a completely different state,” said a leader of the study, Dr. Maiken Nedergaard of the Center for Translational Neuromedicine at the University of Rochester Medical Center.

For centuries, scientists and philosophers have wondered why people sleep and how it affects the brain. Only recently have scientists shown that sleep is important for storing memories. In this study, Nedergaard and her colleagues unexpectedly found that sleep may also be the period when the brain cleanses itself of toxic molecules.

Their results, published in Science, show that during sleep a plumbing system called the glymphatic system may open, letting fluid flow rapidly through the brain. Nedergaard’s lab recently discovered that the glymphatic system helps control the flow of cerebrospinal fluid, a clear liquid surrounding the brain and spinal cord.

“It’s as if Dr. Nedergaard and her colleagues have uncovered a network of hidden caves,” said NINDS program director Dr. Roderick Corriveau. “These exciting results highlight the potential importance of the network in normal brain function.”

Study Identifies Gene for Alcohol Preference in Rats

Selectively bred strains of laboratory rats that either prefer or avoid alcohol have been a mainstay of alcohol research for decades. So-called alcohol-preferring rats voluntarily consume much greater amounts of alcohol than do non-preferring rats. Scientists at NIH now report that a specific gene plays an important role in the alcohol-consuming tendencies of both types of rats.

“This study advances our understanding of the genetics and neurobiology of alcohol consumption in an important animal model of human alcoholism,” says Dr. Kenneth Warren, acting director of the National Institute on Alcohol Abuse and Alcoholism.

As reported online in the Proceedings of the National Academy of Sciences, a diverse team of scientists, led by Dr. David Goldman of NIAAA, used exome sequencing, an approach that comprehensively analyzes the DNA that encodes proteins. They found a severely dysfunctional form of the gene for a brain signaling molecule called metabotropic glutamate receptor 2 (Grm2), known as a stop codon, in alcohol-preferring rats but not in non-preferring rats. The researchers then demonstrated that drugs and genetic changes that block Grm2 increased alcohol consumption in normal rats and mice.

“We’ve long known that genes play an important role in alcoholism,” says Goldman. “However, the genes and genetic variants that cause alcoholism have remained largely unknown. This first discovery of a gene accounting for alcohol preference in a mammalian model illustrates that genomic analysis of a model organism is a powerful approach for a complex disease such as alcoholism.”—compiled by Carla Garnett


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