Cell-type specific molecular and functional analyses to target dorsal horn pain circuitry in mice and non-human primates

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Project Summary Persistent pain remains a major clinical problem because of its high prevalence and the lack of adequate treatment options. The spinal dorsal horn is a major site for the integration of somatosensory information and for circuit-based transformations that underlie persistent pain. The overall goal our work is to develop novel pain therapies that target the dorsal horn circuitry for mechanical allodynia. We use cell type-specific targeting of chemogenic receptors to identify spinal dorsal horn neurons that mediate mechanical allodynia without affecting acute sensation in mice. Mice are a commonly used model system for these studies because of their general similarity to humans, the ease of genetic manipulations and the large number of tools available. However, targeting spinal dorsal horn neurons for therapeutic purposes requires an understanding of the cellular and molecular conservation between species. Rhesus macaque are phylogenetically more similar to humans and with re-engineered tools can serve as a proof-of- principle model system. To this end, we analyzed the molecular and cellular organization of the macaque dorsal horn by single cell transcriptomics and in situ hybridization methods. We compared these data to mouse and human data to generate a harmonized atlas of dorsal horn cell types across species. Here we will 1) Identify the epigenetic landscape of human, macaque and mouse dorsal horn neurons using single nucleus RNA- and ATAC-Seq data together with machine learning-assisted bioinformatic approaches to identify regulatory elements (REs) that drive robust cell type-specific gene expression across species. We will 2) screen candidate REs for cell-type specificity in mice and subsequently macaque and then use the cell type-specific REs to systematically generate a functional map of the dorsal horn across species. Studies proposed here will generate large-scale searchable databases for single cell transcriptomics and open chromatin regions in mice, macaque and human. Importantly, we will have the knowledge and viral vectors needed to pursue macaque proof-of-principle studies of novel therapies for mechanical allodynia.