RNA-seq analysis of FACS-sorted control and Tsc2-deleted nociceptors

The goals of this study are to compare the transcriptomes of control heterozygous and Tuberous sclerosis 2 (Tsc2) homozygous nociceptors that have been enriched by fluorescence-associated cell sorting (FACS) with the aim of identifying differences in genes associated with sensory behavior. Nav1.8-Cre transgenic mice were used to delete Tsc2 as well as express Green fluorescent protein from the Rosa26 locus. Tsc2 deletion constitutively activates mTORC1 signaling cell autonomously. Dissociated dorsal root ganglia from adult mice were FACS-sorted for GFP and analyzed by RNA-seq. We find that a number of sensory behavior associated genes are affected by Tsc2 deletion including Calca, Ntrk1, Mrgpra3, and Nppb. Additionally, profiling of ion channel expression showed a reduction in almost half of expressed sodium, potassium and calcium channel as well as G-protein coupled receptors. Other categories of genes such as transcription factors and ligand-gated ion channels contained an even numbers of up- and downregulated genes with many that did not change as a result of Tsc2 deletion. In addition, expression of most marker genes enriched in Isolectin B4 (IB4) negative neurons were strongly reduced in Tsc2 mutant nociceptors, consistent with reduced sensitivity to heat, which is a modality related to these neurons. We conclude Tsc2 deletion and consequent mTORC1 activation alters gene expression of nociceptors resulting in altered sensory thresholds. L4 dorsal root ganglia contralateral to sciatic nerve crush were harvested 3 days post-injury from mice with Nav1.8-Cre mediated expression of GFP from Rosa26 locus as well as heterozgous (control) or homozygous (cKO) deletion of Tsc2 were FACS-sorted by GFP expression for 3 technical replicates of 100 cells each. RNA-seq data from 4 biological replicates was collected.