NEWS OF THE WEEK
JOHN STAMATOYANNOPOULOS & RAE SENARIGHI
and disease. If a series of studies published last week in Nature and several other Nature research journals are any indication, there will be many more such examples to come (http://nature.com/epigenomeroadmap). The studies report the most comprehensive results to date from the Roadmap Epigenomics Project, the epigenomics version of the Human Genome Project. All the nongerm cells in a particular organism are genetically identical, but not all genes get expressed the same way across cell types. Such variations in gene expression are what differentiate embryonic from adult cells, heart from brain cells, and normal from diseased cells. The epigenomic factors that control differential gene expression include methylation of specific DNA bases, chemical modifications to the proteins called histones that package eukaryotic DNA, and DNA conformation changes that promote the binding of regulatory transcription factors. Researchers in the Roadmap Epigenomics Project—an international collaboration sponsored by the National Institutes of Health—have now mapped the epigenomes of more than 100 human cell types and report on how epigenomics affects diseases such as cancer and Alzheimer’s, differentiation of stem cells into adult cells, and other biological functions. In a Nature commentary, molecular biologist Hendrik G. Stunnenberg of Radboud University, in the Netherlands, says that the community now “plans to determine the epigenomes of every cell type in the human body—estimated to be several hundred to 1,000.”—STU BORMAN
SHUTTERSTOCK
GENOME CHANGES MAPPED IN HUMANS
of the packaging. From there, it migrates into food. “BHT is an FDA-approved food ingredient, but we’re already well down the path of removing it from our cereals. This change is not for safety reasons but because we think consumers will embrace it,” General Mills says. The company claims the move has been under way for more than a year and was not motivated by the petition that Hari launched on Feb 5. Hari also has called on Kellogg’s to remove BHT. There is no scientific evidence that BHT is harmful in the amounts used in packaged food. Indeed, in small amounts, it may have anticancer effects similar to those provided by naturally occurring antioxidants. But studies of larger doses have shown mixed results. In some mouse and rat studies, BHT appeared to trigger cancer in the forestomach, an organ that humans don’t have. BHT is approved for use in both the U.S. and Europe, but Hari points out that cereals marketed in Europe by General Mills and Kellogg’s do not contain the additive. Already, General Mills says, the Cheerios, Trix, Kix, and Lucky Charms it sells in the U.S. contain no BHT. Cheerios products, for example, rely on vitamin E, also called mixed tocopherols, to keep them fresh. Other label-friendly antioxidants available to cereal companies include vitamins A and C and extracts of rosemary and thyme.—MELODY BOMGARDNER
EPIGENOMICS: Most comprehensive
results to date in collaborative
epigenome-mapping project Key factors that affect gene expression include DNA methylation, ESEARCHERS REPORTED last week that a chemical DNA-methylation gene called uhrf1 is a momodifications lecular trigger for inflammatory bowel disto histones, and conformational ease (Proc. Natl. Acad. Sci. USA 2015, DOI: 10.1073/ changes that pnas.1424089112). It was alattract geneready known that immunity DNA methylation regulating and genetics play a role in transcription the disease. “But we’ve factors (colored found that it is not just shapes). the immune genes themRegulatory selves but also the regulaDNA tion of those genes through epigenetics that can cause problems,” says corresponding author and Duke University cell biHistone ologist Michel Bagnat. modifications The finding is just one example of the importance of epigenetics, or epigenomics—the study of how modifications to a cell’s genome can Nucleosome (composed of histones) influence human development, health,
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THE FOOD BABE’S CEREAL TAKEDOWN FOOD INGREDIENTS: General
Mills removes preservative; is target of blogger
N THE WAKE of a campaign by the controversial
Cinnamon Toast Crunch will no longer contain BHT.
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blogger Vani Hari, who goes by the name Food Babe, General Mills says it is removing the antioxidant butylated hydroxytoluene (BHT) from its cereals. The action is the latest to be trumpeted by Hari, who is not a scientist but whose blogging about food additives has the ability to make big companies jump. Last year the Subway sandwich chain removed a dough conditioner, azodicarbonamide, from its breads after similar haranguing by Hari. Many of America’s favorite cereal brands contain a dash of BHT, a synthetic antioxidant that prevents vegetable oils from going rancid. BHT may be added directly to cereal, though it is commonly added to the plastic or wax paper liner CEN.ACS.ORG
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FEBRUARY 23, 2015
