A peptide encoded within a 5′ untranslated region promotes pain sensitization in mice

Abstract

Translational regulation permeates neuronal function. Nociceptors are sensory neurons responsible for the detection of harmful stimuli. Changes in their activity, termed plasticity, are intimately linked to the persistence of pain. Although inhibitors of protein synthesis robustly attenuate pain-associated behavior, the underlying targets that support plasticity are largely unknown. Here, we examine the contribution of protein synthesis in regions of RNA annotated as noncoding. Based on analyses of previously reported ribosome profiling data, we provide evidence for widespread translation in noncoding transcripts and regulatory regions of mRNAs. We identify an increase in ribosome occupancy in the 5′ untranslated regions of the calcitonin gene-related peptide (CGRP/Calca). We validate the existence of an upstream open reading frame (uORF) using a series of reporter assays. Fusion of the uORF to a luciferase reporter revealed active translation in dorsal root ganglion neurons after nucleofection. Injection of the peptide corresponding to the calcitonin gene-related peptide–encoded uORF resulted in pain-associated behavioral responses in vivo and nociceptor sensitization in vitro. An inhibitor of heterotrimeric G protein signaling blocks both effects. Collectively, the data suggest pervasive translation in regions of the transcriptome annotated as noncoding in dorsal root ganglion neurons and identify a specific uORF-encoded peptide that promotes pain sensitization through GPCR signaling.

Global analyses of mRNA expression in human sensory neurons reveal eIF5A as a conserved target for inflammatory pain

“…Inhibitors that prevent translation elongation diminish pain amplification behaviors 26,29,98 . Given that inflammatory mediators increase ribosome occupancy in 5′UTRs, it would be interesting to determine what effects eIF5A inhibition has on translation start sites and if they mirror those increased by inflammatory cues 30 . A second possibility is that peptide release is impaired upon reduction of eIF5A.…”

A role for translational regulation by S6 kinase and a downstream target in inflammatory pain

“…However, activation of S6Ks appears to promote re-initiation. Given that a uORF has been linked to nociception, this is an interesting possibility ( Barragan-Iglesias et al, 2021).…”

“…Multielectrode array (MEA) experiments were performed as described previously with minor modifications (Barragan‐Iglesias et al, 2021). Briefly, DRG neurons were seeded on 48‐well MEA plates (Axion Biosystems, USA) which had been coated with 0.1% PEI and 20‐μg·ml −1 laminin at 30,000 neurons per well.…”

“…Multielectrode array (MEA) experiments were performed as described previously with minor modifications (Barragan-Iglesias et al, 2021).…”

Ion Mobility Coupled to a Time-of-Flight Mass Analyzer Combined With Fragment Intensity Predictions Improves Identification of Classical Bioactive Peptides and Small Open Reading Frame-Encoded Peptides

“…The coding potential of these small open reading frames (sORF)encoded peptides (SEPs) has been a point of dispute for years, but advances in high-throughput methods and integration of several datatypes (reviewed in Peeters and Menschaert, 2020) has demonstrated their potential as biological regulators. Recently, a peptide encoded in the 5' untranslated region (UTR) of the calcitonin gene-related peptide (CGRP/Calca) has been reported to trigger pain-associated behavioral responses in vivo, emphasizing a role for upstream open reading frame (uORF) translation in nociceptor plasticity (Barragan-iglesias et al, 2021). Besides uORFs, sORF-encoded peptides translated from originally "non-coding" RNAs are another category of peptides reported with functions in important processes like inflammation and metabolism (Chen et al, 2021).…”