Differential Effects of Tissue-Specific Deletion of BOSS on Feeding Behaviors and Energy Metabolism

Food intake and energy metabolism are tightly controlled to maintain stable energy homeostasis and healthy states. Thus, animals detect their stored energy levels, and based on this, they determine appropriate food intake and meal size. Drosophila melanogaster putative G protein-coupled receptor, Bride of sevenless (BOSS) is a highly evolutionarily conserved protein that responds to extracellular glucose levels in order to regulate energy homeostasis. To address how BOSS regulates energy homeostasis, we characterized a boss mutant by assessing its food intake and stored energy levels. Boss mutants exhibited increased food intake but decreased stored triacylglyceride levels. Using boss-GAL4 drivers, we found that boss is expressed in select tissues that are involved in nutrient sensing and food intake, in a subset of neurons in brain and chemosensory organs, in fat body, and in endocrine cells in gut (enteroendocrine cells). Flies with tissue-specific boss knockdowns in these tissues had abnormal stored energy levels and abnormal food intake. These results suggest that BOSS in either neurons or peripheral nutrient-sensing tissues affects energy homeostasis in ways that relate to the sensing of nutrients and regulation of food intake.

食物摄取与能量代谢受到精密调控，以维持稳定的能量稳态（energy homeostasis）与健康生理状态。动物可感知自身储存的能量水平，并以此为依据调整适宜的食物摄取量与进餐规模。黑腹果蝇（Drosophila melanogaster）的推定G蛋白偶联受体（G protein-coupled receptor）Bride of sevenless（简称BOSS）是一类高度进化保守的蛋白，可通过响应细胞外葡萄糖水平来调控能量稳态。为探究BOSS调控能量稳态的具体机制，本研究通过评估食物摄取量与储能水平，对boss突变体进行了表型鉴定。结果显示，boss突变体的食物摄取量升高，但储能甘油三酯（triacylglyceride）水平降低。借助boss-GAL4驱动系统，我们发现boss在参与营养感知与食物摄取的特定组织中表达，具体包括脑与化学感受器官中的部分神经元、脂肪体，以及肠道内分泌细胞（肠内分泌细胞，enteroendocrine cells）。在上述组织中进行boss组织特异性敲低的果蝇，其储能水平与食物摄取量均出现异常。上述结果表明，无论是在神经元还是外周营养感知组织中表达的BOSS，均可通过调控营养感知与食物摄取的途径影响能量稳态。