A novel role as appetite suppressant for BH4, a well-known enzyme cofactor
Fat is the primary long-term energy storage molecule in animals, and the control of fat levels is critical for survival. In mammals, the hormone leptin induces eating in response to fat loss, but so far, no corresponding signal has been identified, either in mammals or any other animal, that inhibits eating in response to fat gain. Because fruit flies replicate many of the feeding-related regulatory mechanisms and genes known to operate in humans, they make a good model for the search for such an inhibitory signal. To conduct their search, the authors focused on short non-coding RNAs or microRNAs , which are well-known inhibitors of gene expression. They first searched for microRNAs that, when overexpressed in fat tissue, affected feeding behavior, and second for the gene targets of those microRNAs. They identified a microRNA called miR-iab-4, which increased feeding by more than 27%, and a target gene called purple, which was expressed in fat bodies. Reducing purple expression ...