RESEARCH ARTICLE RNA-Seq Analysis of Human Trigeminal and Dorsal Root Ganglia

The chemosensory capacity of the somatosensory system relies on the appropriate expres-sion of chemoreceptors, which detect chemical stimuli and transduce sensory information into cellular signals. Knowledge of the complete repertoire of the chemoreceptors express-ed in human sensory ganglia is lacking. This study employed the next-generation sequenc-ing technique (RNA-Seq) to conduct the first expression analysis of human trigeminal ganglia (TG) and dorsal root ganglia (DRG). We analyzed the data with a focus on G-protein coupled receptors (GPCRs) and ion channels, which are (potentially) involved in chemo-sensation by somatosensory neurons in the human TG and DRG. For years, transient re-ceptor potential (TRP) channels have been considered the main group of receptors for chemosensation in the trigeminal system. Interestingly, we could show that sensory ganglia also express a panel of different olfactory receptors (ORs) with putative chemosensory function. To characterize OR expression in more detail, we performed microarray, semi-quantitative RT-PCR experiments, and immunohistochemical staining. Additionally, we an-alyzed the expression data to identify further known or putative classes of chemoreceptors in the human TG and DRG. Our results give an overview of the major classes of chemore-ceptors expressed in the human TG and DRG and provide the basis for a broader under-standing of the reception of chemical cues