Raw SEPhluorin FRAP Imaging Data for Fig 2B.

Modulation of neurotransmission is key for organismal responses to varying physiological contexts such as during infection, injury, or other stresses, as well as in learning and memory and for sensory adaptation. Roles for cell autonomous neuromodulatory mechanisms in these processes have been well described. The importance of cell non-autonomous pathways for inter-tissue signaling, such as gut-to-brain or glia-to-neuron, has emerged more recently, but the cellular mechanisms mediating such regulation remain comparatively unexplored. Glycoproteins and their G protein-coupled receptors (GPCRs) are well-established orchestrators of multi-tissue signaling events that govern diverse physiological processes through both cell-autonomous and cell non-autonomous regulation. Here, we show that follicle stimulating hormone receptor, FSHR-1, the sole Caenorhabditis elegans ortholog of mammalian glycoprotein hormone GPCRs, is important for cell non-autonomous modulation of synaptic transmission. Inhibition of fshr-1 expression reduces muscle contraction and leads to synaptic vesicle accumulation in cholinergic motor neurons. The neuromuscular and locomotor defects in fshr-1 loss-of-function mutants are associated with an underlying accumulation of synaptic vesicles, build-up of the synaptic vesicle priming factor UNC-10/RIM, and decreased synaptic vesicle release from cholinergic motor neurons. Restoration of FSHR-1 to the intestine is sufficient to restore neuromuscular activity and synaptic vesicle localization to fshr-1-deficient animals. Intestine-specific knockdown of FSHR-1 reduces neuromuscular function, indicating FSHR-1 is both necessary and sufficient in the intestine for its neuromuscular effects. Re-expression of FSHR-1 in other sites of endogenous expression, including glial cells and neurons, also restored some neuromuscular deficits, indicating potential cross-tissue regulation from these tissues as well. Genetic interaction studies provide evidence that downstream effectors gsa-1/GαS, acy-1/adenylyl cyclase and sphk-1/sphingosine kinase and glycoprotein hormone subunit orthologs, GPLA-1/GPA2 and GPLB-1/GPB5, are important for intestinal FSHR-1 modulation of the NMJ. Together, our results demonstrate that FSHR-1 modulation directs inter-tissue signaling systems, which promote synaptic vesicle release at neuromuscular synapses.神经传递的调控是生物体应对感染、损伤或其他应激等不同生理状态，以及学习记忆与感觉适应的关键。细胞自主性神经调控机制在这些过程中的作用已得到充分阐释。细胞非自主性通路介导的组织间信号传导（如肠-脑或胶质细胞-神经元信号）的重要性近年来才逐渐显现，但介导此类调控的细胞机制仍相对未被充分探索。 糖蛋白及其G蛋白偶联受体（G protein-coupled receptors, GPCRs）是多组织信号事件的公认调控者，可通过细胞自主性与细胞非自主性调控参与多种生理过程。本研究发现，促卵泡激素受体（FSHR-1）——哺乳动物糖蛋白激素GPCRs在秀丽隐杆线虫中的唯一同源蛋白，可介导突触传递的细胞非自主性调控。抑制fshr-1的表达会降低肌肉收缩能力，并导致胆碱能运动神经元内突触囊泡堆积。fshr-1功能缺失突变体的神经肌肉与运动缺陷，与突触囊泡堆积、突触囊泡启动因子UNC-10/RIM的积累，以及胆碱能运动神经元突触囊泡释放量降低密切相关。将FSHR-1重新表达于肠道中，即可恢复fshr-1缺陷动物的神经肌肉活性与突触囊泡定位。肠道特异性敲低FSHR-1会降低神经肌肉功能，表明FSHR-1在肠道中既是其神经肌肉效应所必需的，也是足够的。在其他内源性表达位点（包括胶质细胞与神经元）重新表达FSHR-1，也可部分改善神经肌肉缺陷，提示这些组织也可能介导跨组织调控。遗传互作研究表明，下游效应因子gsa-1/GαS、acy-1/腺苷酸环化酶、sphk-1/鞘氨醇激酶，以及糖蛋白激素亚基同源蛋白GPLA-1/GPA2与GPLB-1/GPB5，对于肠道FSHR-1调控神经肌肉接头（neuromuscular junction, NMJ）至关重要。综上，本研究结果表明，FSHR-1调控可介导跨组织信号通路，进而促进神经肌肉突触处的突触囊泡释放。