Until now, no one knew the specific trigger that controls the extent to which cells called preadipocytes turn into fat cells. Harvard researchers have identified the genes GATA-2 and GATA-3 as the molecular gatekeepers of that transition. When the genes are defective or missing, preadipocytes change into fat cells and, conversely, when the genes are expressed, preadipocytes remain fixed in a pre-fat stasis and do not accumulate lipids. “If a gene is controlling this critical gate, then one can control the fat tissue in two ways,” said Gökhan Hotamisligil, associate professor in the Division of Biological Sciences and Department of Nutrition, who led the study. “Theoretically, one can enhance or diminish the formation of fat cells depending on how one manipulates the genes.” Qiang Tong, research fellow in nutrition in the Department of Nutrition, served as first author of the paper.