When it comes to fat, fruit flies are more like people than we thought. The insects, researchers have found, churn out the hormone leptin—the same hormone that helps control appetite and metabolism in humans. Leptin has been the subject of intense interest among researchers—and until now, they thought that only vertebrates produced it. The find opens doors to better understand just what leptin does. The discovery, published today in Cell, came about when postdoctoral fellow Akhila Rajan of Harvard Medical School in Boston and her adviser, Norbert Perrimon, engineered flies that lacked a nutrient-sensing protein called Upd2. Normally, flies without Upd2 look metabolically like they're famished. But when Rajan inserted the human leptin gene into her flies, they didn't have this problem. The researchers conclude that Upd2 is the "functional homolog" of leptin, meaning the protein in flies acts very much like leptin does in people. Because flies are relatively easy to study in the lab, it's hoped that the discovery will unlock more secrets about the hormone.
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