In mammals, the perception of pain is initiated by the transduction of noxious stimuli through specialized ion channels and receptors expressed by nociceptive sensory neurons. The molecular mechanisms responsible for the specification of distinct sensory modality are, however, largely unknown. We show here that Runx1, a Runt domain transcription factor, is expressed in most nociceptors during embryonic development but in adult mice, becomes restricted to nociceptors marked by expression of the neurotrophin receptor Ret. In these neurons, Runx1 regulates the expression of many ion channels and receptors, including TRP class thermal receptors, Na+-gated, ATP-gated, and H+-gated channels, the opioid receptor MOR, and Mrgpr class G protein coupled receptors. Runx1 also controls the lamina-specific innervation pattern of nociceptive afferents in the spinal cord. Moreover, mice lacking Runx1 exhibit specific defects in thermal and neuropathic pain. Thus, Runx1 coordinates the phenotype of a large cohort of nociceptors, a finding with implications for pain therapy.
