Transcriptome analysis of familial dysautonomia reveals tissue-specific gene expression disruption in the peripheral nervous system
Familial Dysautonomia (FD) is a rare recessive neurodevelopmental disease caused by a splice site mutation in the Elongator acetyltransferase complex subunit 1 (ELP1) leading to tissue-specific skipping of exon 20 and reduction of the ELP1 protein, distinctly in the central nervous system (CNS) and peripheral nervous system (PNS).  Here we performed a transcriptome-wide study to dissect the molecular mechanisms underlying FD in specific neuronal tissues from the FD phenotypic mouse which expresses human ELP1, including the dorsal root ganglion (DRG), trigeminal ganglion (TG), medulla (MED), cortex, and spinal cord (SC). We focused our analyses on differentially expressed genes (DEGs) representing the most dominant transcriptomic alterations; and on genes in co-expression modules that are highly correlated with full-length ELP1 expression (ELP1 dose-responsive genes). We identified higher number of DEGs (342) in the PNS (DRG, TG) as compared to the CNS (MED, SC, Cortex) (143). ELP1 dose-responsive genes are only found in DRG, TG, and MED, not in Cortex or SC, tissues. Gene Ontology analyses of both DEGs and ELP1-dose-responsive genes highlight the regulation of neurotransmitters. The transcriptome-wide signals were highly convergent between PNS tissues (DRG and TG) but not among CNS tissues. Those convergent genes were enriched for known protein-protein interactions and cell type-specific markers defining myelinated neurons and peptidergic nociceptors. Our findings support the involvement of specific neuronal subtypes underlying the PNS phenotypes in FD. Our study comprehensively investigates transcriptome-wide alterations in FD neuronal tissues and identifies the functional dysregulations in the peripheral nervous system contributing to disease. Overall design: 3-month old FD and Control mice were dissected for cortex, dorsal root ganglion, medulla, spinal cord and trigeminal ganglion neurons and paired-end mRNA-seq was performed.  124 Libraries were generated.