obesity genes
Unraveling the Biocircuitry of Obesity
Posted on by Dr. Francis Collins
Caption: Mouse neurons (purple), with their nuclei (blue) and primary cilia (green).
Credit: Yi Wang, Vaisse Lab, UCSF
Obesity involves the complex interplay of diet, lifestyle, genetics, and even the bacteria living in the gut. But there are other less-appreciated factors that are likely involved, and a new NIH-supported study suggests one that you probably never would have imagined: antenna-like sensory projections on brain cells.
The study in mice, published in the journal Nature Genetics [1], suggests these neuronal projections, called primary cilia, are a key part of a known “hunger circuit,” which receives signals from other parts of the body to control appetite. The researchers add important evidence in mouse studies showing that changes in the primary cilia can produce a short circuit, impairing the brain’s ability to regulate appetite and leading to overeating and obesity.
Flipping a Genetic Switch on Obesity?
Posted on by Dr. Francis Collins
When weight loss is the goal, the equation seems simple enough: consume fewer calories and burn more of them exercising. But for some people, losing and keeping off the weight is much more difficult for reasons that can include a genetic component. While there are rare genetic causes of extreme obesity, the strongest common genetic contributor discovered so far is a variant found in an intron of the FTO gene. Variations in this untranslated region of the gene have been tied to differences in body mass and a risk of obesity [1]. For the one in six people of European descent born with two copies of the risk variant, the consequence is carrying around an average of an extra 7 pounds [2].
Now, NIH-funded researchers reporting in The New England Journal of Medicine [3] have figured out how this gene influences body weight. The answer is not, as many had suspected, in regions of the brain that control appetite, but in the progenitor cells that produce white and beige fat. The researchers found that the risk variant is part of a larger genetic circuit that determines whether our bodies burn or store fat. This discovery may yield new approaches to intervene in obesity with treatments designed to change the way fat cells handle calories.
Genetic Studies Yield New Insights into Obesity
Posted on by Dr. Francis Collins
Today, we hear a great deal about which foods to eat and which to avoid to maintain a healthy body. Though we know that one of the strongest contributors to body weight is heredity, there has been less specific information available about the genetics underlying obesity. But research in this area is progressing at a phenomenal pace, and new genomic discoveries are helping to bring into better focus how our bodies store fat and how the complex interplay of genetics, diet, behavior, and other factors determine whether we can readily maintain a healthy body weight, or whether it takes a lot of work to do so.
Two papers in Nature provide lots of fresh clues into the genetic factors involved in predisposing to obesity. Researchers in the international Genetic Investigation of ANthropometric Traits (GIANT) Consortium, more than 500 strong and including some of the members of my own NIH research lab (including me), examined the genomes of more than half a million people to look for genes and regions of chromosomes that play a role in body fat distribution and obesity. They turned up over 140 genetic locations that, like low-intensity voices in a choir of many, contribute to these traits. Further analyses of the specific genes located in these regions suggest the possibility that the programming behind how fat cells form may influence their distribution, a discovery that could lead to exploitable findings down the road.
