In vitroandin vivoeffects on neural crest stem cell differentiation by conditional activation of Runx1 short isoform and its effect on neuropathic pain behavior

Abstract

IntroductionRunx1, a Runt domain transcription factor, controls the differentiation of nociceptors that express the neurotrophin receptor Ret, regulates the expression of many ion channels and receptors, and 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. We investigated whether conditional activation of Runx1 short isoform (Runx1a), which lacks a transcription activation domain, influences differentiation of neural crest stem cells (NCSCs) in vitro and in vivo during development and whether postnatal Runx1a activation affects the sensitivity to neuropathic pain.MethodsWe activated ectopic expression of Runx1a in cultured NCSCs using the Tet-ON gene regulatory system during the formation of neurospheres and analyzed the proportion of neurons and glial cells originating from 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 of offsprings. We also examined whether DOX-induced activation of Runx1a in adult mice affects their sensitivity to mechanical stimulation following a constriction injury of the sciatic nerve.ResultsEctopic Runx1a expression in cultured NCSCs resulted in predominantly glial differentiation. Offsprings in which Runx1a had been 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.ConclusionThese data suggest that Runx1a has a specific role in NCSC development and that modulation of Runx1a activity may reduce mechanical hypersensitivity associated with neuropathic pain.

New insights into the role of Runx1 in epithelial stem cell biology and pathology

“…The common theme emerging for Runx1 function across tissues is its implication in stem cell regulation and in cancer. In addition to hematopoietic stem cells and neural progenitors [Kanaykina et al, 2010] in the last few years Runx1 has been reportedly expressed in three other stem cell populations: HF, oral epithelium, and potentially in the intestine. Strong functional and genetic studies implicate Runx1 as a key regulator of both HSCs and HFSCs function.…”

“…Moreover Runx1 plays a role in neural progenitor cell proliferation. Details on Runx1 function in the hematopoietic system, leukemia, and nervous system development have been discussed elsewhere and are beyond the scope of this review [Chen et al, 2009; Kanaykina et al, 2010; Mangan and Speck, 2011]. This prospect focuses on recent findings pertaining to Runx1 function and molecular interactions in epithelial tissue homeostasis and disease biology, particularly skin, oral, and intestinal tissues.…”

“…All Runx1 isoforms are expressed in the hematopoietic system at different stages of development [Challen and Goodell, 2010], but little is known about their expression in other tissues. Notably, Runx1a lacks the protein binding domains but binds DNA strongly and thus potentially acts as an inhibitor to Runx1b and c. In particular it has been implicated in affecting differentiation of neural crest SCs [Kanaykina et al, 2010]. To date there are no data on Runx1a in the skin, but in keratinocytes Runx1b, but not Runx1c, is detected [Ortt et al, 2008].…”

RUNX transcription factors: orchestrators of development

“…(Kramer et al, 2006) Runx1a iOE Sox10-rtTA Nervous system Retarded fetal growth, pigment defects, megacolon, and dystrophic DRG. (Kanaykina et al, 2010) Runx1 cKO Krt5-Cre Epidermis Defects in hair shape and structure. (Raveh et al, 2006)…”

Integration of ChIP-seq and machine learning reveals enhancers and a predictive regulatory sequence vocabulary in melanocytes

“…It is also notable that one of the top 6-mers (ranked fourth) is predicted to bind PAX3, a key regulator of melanocyte differentiation (Lang et al 2005) which can cause Waardenburg syndrome type 1 and type 3 when mutated (OMIM:193500 and OMIM:148820, respectively). In addition, CREB1, SOX5, and RUNX-family TFs (predicted to bind 6-mers ranked fifth, eighth, and ninth, respectively) have been shown to play roles in regulating gene expression in melanocytes (Tada et al 2002;Raveh et al 2005;Saha et al 2006;Kingo et al 2008;Stolt et al 2008;Kanaykina et al 2010;Mizutani et al 2010).…”