In vitro and in vivo effects on neural crest stem celldifferentiation by conditional activation of Runx1 short isoform and its effecton neuropathic pain behavior

• INTRODUCTION: Runx1, a Runt domain transcription factor, controls thedifferentiation of nociceptors that express the neurotrophin receptor Ret,regulates the expression of many ion channels and receptors, and controls thelamina-specific innervation pattern of nociceptive afferents in the spinal cord. Moreover, mice lacking Runx1 exhibit specific defects in thermal and neuropathic pain. We investigated whether conditional activation of Runx1 short isoform(Runx1a), which lacks a transcription activation domain, influencesdifferentiation of neural crest stem cells (NCSCs) in vitro and in vivo duringdevelopment and whether postnatal Runx1a activation affects the sensitivity toneuropathic pain. METHODS: We activated ectopic expression of Runx1a in cultured NCSCs using the Tet-ON gene regulatory system during the formation ofneurospheres and analyzed the proportion of neurons and glial cells originatingfrom NCSCs. In in vivo experiments we applied doxycycline (DOX) to pregnant mice (days 8-11), i.e. when NCSCs actively migrate, and examined the phenotype ofoffsprings. We also examined whether DOX-induced activation of Runx1a in adultmice affects their sensitivity to mechanical stimulation following a constrictioninjury of the sciatic nerve. RESULTS: Ectopic Runx1a expression in cultured NCSCsresulted in predominantly glial differentiation. Offsprings in which Runx1a hadbeen activated showed retarded growth and displayed megacolon, pigment defects,and dystrophic dorsal root ganglia. In the neuropathic pain model, the threshold for mechanical sensitivity was markedly increased following activation of Runx1a.CONCLUSION: These data suggest that Runx1a has a specific role in NCSCdevelopment and that modulation of Runx1a activity may reduce mechanicalhypersensitivity associated with neuropathic pain.

Nyckelord

Development

Gene regulation

Neuroglia

Pain

Sensory neuron

Transcription factor

MEDICINE

MEDICIN

Neuroscience

Neurovetenskap

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