National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892.
Department of Entomology, University of Maryland, College Park, MD 20742.
Proc Natl Acad Sci U S A. 2021 Jun 8;118(23). doi: 10.1073/pnas.2004685118.
The construction and maturation of the postsynaptic apparatus are crucial for synapse and dendrite development. The fundamental mechanisms underlying these processes are most often studied in glutamatergic central synapses in vertebrates. Whether the same principles apply to excitatory cholinergic synapses, such as those found in the insect central nervous system, is not known. To address this question, we investigated a group of projection neurons in the larval visual system, the ventral lateral neurons (LNvs), and identified nAchRα1 () and nAchRα6 () as the main functional nicotinic acetylcholine receptor (nAchR) subunits in the larval LNvs. Using morphological analyses and calcium imaging studies, we demonstrated critical roles of these two subunits in supporting dendrite morphogenesis and synaptic transmission. Furthermore, our RNA sequencing analyses and endogenous tagging approach identified distinct transcriptional controls over the two subunits in the LNvs, which led to the up-regulation of and down-regulation of during larval development as well as to an activity-dependent suppression of Additional functional analyses of synapse formation and dendrite dynamics further revealed a close association between the temporal regulation of individual nAchR subunits and their sequential requirements during the cholinergic synapse maturation. Together, our findings support transcriptional control of nAchR subunits as a core element of developmental and activity-dependent regulation of central cholinergic synapses.
突触后装置的构建和成熟对于突触和树突的发育至关重要。这些过程的基本机制通常在脊椎动物的谷氨酸能中枢突触中进行研究。目前尚不清楚相同的原则是否适用于兴奋性胆碱能突触，例如昆虫中枢神经系统中的突触。为了解决这个问题，我们研究了幼虫视觉系统中的一组投射神经元，即腹外侧神经元（LNvs），并确定 nAchRα1 () 和 nAchRα6 () 是幼虫 LNvs 中主要的功能性烟碱型乙酰胆碱受体（nAchR）亚基。通过形态分析和钙成像研究，我们证明了这两个亚基在支持树突形态发生和突触传递方面的关键作用。此外，我们的 RNA 测序分析和内源性标记方法确定了 LNvs 中这两个亚基的转录控制存在明显差异，导致在幼虫发育过程中上调 和下调 ，以及活动依赖性抑制 。对突触形成和树突动力学的进一步功能分析进一步揭示了单个 nAchR 亚基的时间调节与其在胆碱能突触成熟过程中的顺序需求之间的密切关联。总之，我们的研究结果支持 nAchR 亚基的转录控制是中枢胆碱能突触发育和活动依赖性调节的核心要素。
