Members of the CUGBP Elav-Like Family of RNA-Binding Proteins are Expressed in Distinct Populations of Primary Sensory Neurons

Abstract

Primary sensory Dorsal Root Ganglia (DRG) neurons are diverse, with distinct populations that respond to specific stimuli. Previously, we observed that functionally distinct populations of DRG neurons express mRNA transcript variants with different 3` untranslated regions (3`UTRs). 3`UTRs harbor binding sites for interaction with RNA-binding proteins (RBPs) critical for targeting mRNAs to subcellular domains, modulating transcript stability and regulating the rate of translation. In the current study we sought to determine if 3`UTR-binding proteins are restricted to specific DRG neuron populations. Analysis of publicly available single-cell RNA-Sequencing (scRNA-Seq) data generated from adult mice revealed that 17 3`UTR-binding RBPs were enriched in specific populations of DRG neurons. This included 4 members of the CUGBP Elav-Like Family (CELF). CELF2 and CELF4 were enriched in peptidergic, CELF6 in both peptidergic and nonpeptidergic and CELF3 in tyrosine hydroxylase-expressing neurons. CELF4 is a known regulator of neural excitability, likely through modulation of protein synthesis via binding to interaction sites within the 3`UTRs of mRNAs. Immunofluorescence studies showed 60% of CELF4+ neurons are small diameter C fibers and 33% medium diameter myelinated (likely Aδ) fibers. Co-expression analyses using transcriptomic data and quantitative immunofluorescence revealed that CELF4 is enriched in nociceptive neurons that express GFRA3, CGRP and the capsaicin receptor TRPV1. Finally, genes with CELF4 binding motifs expressed in CELF4+ neurons are significantly associated with gene ontology (GO) terms such as RNA-binding and translation. We propose that CELF4 may therefore control a novel regulon that coordinates the translation of mRNAs encoding components of the protein translation apparatus in nociceptors.

RNA‐binding proteins in pain

“…The expression of 3′UTR‐binding RBPs of distinct cell populations in DRG was recently described, finding several members of the C UG triplet repeat E lav‐ l ike f amily (CELF) of RBPs exhibit cell‐type specific patterns of expression (Grlickova‐Duzevik et al, 2023). CELF4 in particular was enriched in nociceptive groups of neurons in both rodent and macaque DRG.…”