Single cell transcriptomics of vomeronasal neuroepithelium reveals a differential endoplasmic reticulum environment amongst neuronal subtypes. Single cell transcriptomics of vomeronasal neuroepithelium reveals a differential endoplasmic reticulum environment amongst neuronal subtypes

Specialized chemosensory signals elicit innate social behaviors in individuals of several vertebrate species, a process that is thought to be mediated via the accessory olfactory system (AOS). The AOS comprising the peripheral sensory vomeronasal organ (VNO) has evolved elaborate molecular and cellular mechanisms to detect chemo signals. To gain insight into the cell types, developmental gene expression patterns and functional differences amongst neurons, we performed single cell transcriptomics of the mouse vomeronasal sensory epithelium. Our analysis reveals diverse cell types with gene expression patterns specific to each. Pseudo-time developmental analysis indicates that neurons originating from common progenitors diverge in their gene expression during maturation with transient and persistent transcription factor expression at critical branch points. Comparative analysis across two of the major neuronal subtypes that express divergent GPCR families and the G-protein subunits Gnai2 or Gnao1, reveals significantly higher expression of endoplasmic reticulum (ER) associated genes within Gnao1 neurons. We also specific combinatorial expression pattern of V2R and H2-Mv genes in Gnao1 neurons. These gene expression patterns, along with differential localization of ER chaperones and structural proteins indicate fundamental differences in ER function associated with neuronal differentiation. Overall design: Vomeronasal organ from male and female C57BL/6J animals was dissected and processed separately. The neuroepithelium was separated and single cell dissociation was performed. The dissociated suspension was used for single cell RNA sequencing on 10X genomics platform

多种脊椎动物个体的先天性社交行为可由特异性化学感应信号诱发，该过程被认为通过辅助嗅觉系统（accessory olfactory system, AOS）介导。由外周感觉犁鼻器（vomeronasal organ, VNO）组成的辅助嗅觉系统，已演化出复杂的分子与细胞机制以探测化学信号。为深入解析神经元的细胞类型、发育性基因表达模式及功能差异，本研究对小鼠犁鼻感觉上皮开展了单细胞转录组学分析。本研究的分析结果揭示了多种细胞类型，且每种细胞均具有特异性的基因表达模式。拟时间发育分析显示，源自共同祖细胞的神经元在成熟过程中基因表达模式发生分化，关键分支点处存在转录因子的瞬时与持续表达。对表达不同G蛋白偶联受体（G protein-coupled receptor, GPCR）家族以及G蛋白亚基Gnai2或Gnao1的两种主要神经元亚型进行比较分析后发现，Gnao1神经元中内质网（endoplasmic reticulum, ER）相关基因的表达水平显著更高。我们还发现Gnao1神经元中存在V2R与H2-Mv基因的特异性组合表达模式。这些基因表达模式，结合ER伴侣蛋白与结构蛋白的差异定位，表明与神经元分化相关的ER功能存在根本性差异。实验整体设计：分别解剖并独立处理C57BL/6J品系雌雄小鼠的犁鼻器，分离其神经上皮并进行单细胞解离，将解离后的细胞悬液用于10X Genomics平台的单细胞RNA测序。