Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
Centre for Neural Circuits and Behaviour, University of Oxford, Oxford OX1 3TA, UK.
Cell Rep. 2020 Dec 15;33(11):108516. doi: 10.1016/j.celrep.2020.108516.
Sexual dimorphism in Drosophila courtship circuits requires the male-specific transcription factor fru, which is alternatively spliced to encode the Fru, Fru, and Fru isoforms. Most fru-positive neurons express multiple variants; however, the functional significance of their co-expression remains undetermined. Do co-expressed isoforms each play unique roles to jointly regulate dimorphism? By focusing on fru-positive olfactory receptor neurons (ORNs), here, we show that Fru and Fru are both required for males' age-dependent sensitization to aphrodisiac olfactory cues in a cell-autonomous manner. Interestingly, Fru expression is upregulated with age in Or47b and Ir84a ORNs, and its overexpression mimics the effect of age in elevating olfactory responses. Mechanistically, Fru and Fru synergistically mediate response sensitization through cooperation of their respective downstream effectors, namely, PPK25 and PPK23, which are both required for forming a functional amplification channel in ORNs. Together, these results provide critical mechanistic insight into how co-expressed Fru isoforms jointly coordinate dimorphic neurophysiology.
果蝇求偶回路中的性别二态性需要雄性特异性转录因子 fru，它通过选择性剪接编码 Fru、Fru 和 Fru 同工型。大多数 fru 阳性神经元表达多种变体；然而，它们共表达的功能意义仍未确定。共表达的同工型是否各自发挥独特的作用来共同调节二态性？在这里，我们通过关注 fru 阳性嗅觉受体神经元 (ORN)，表明 Fru 和 Fru 都以细胞自主性的方式雄性对性引诱嗅觉线索的年龄依赖性敏感化所必需。有趣的是，在 Or47b 和 Ir84a ORNs 中，Fru 的表达随年龄增长而上调，其过表达模拟了年龄对提高嗅觉反应的影响。在机制上，Fru 和 Fru 通过各自下游效应子的协同作用来共同介导反应敏化，即 PPK25 和 PPK23，它们都需要在 ORNs 中形成功能放大通道。总之，这些结果为共表达的 Fru 同工型如何共同协调二态神经生理学提供了重要的机制见解。
