The ependyma of the spinal cord harbours stem cells which are activated by traumatic spinal cord injury. Progenitor-like cells in the central canal (CC) are organized in spatial domains. The cells lining the lateral aspects combine characteristics of ependymocytes and radial glia (RG) whereas in the dorsal and ventral poles, CC-contacting cells have the morphological phenotype of RG and display complex electrophysiological phenotypes. The signals that may affect these progenitors are little understood. Because ATP is massively released after spinal cord injury, we hypothesized that purinergic signalling plays a part in this spinal stem cell niche. We combined immunohistochemistry, in vitro patch-clamp whole-cell recordings and Ca2+ imaging to explore the effects of purinergic agonists on ependymal progenitor-like cells in the neonatal (P1–P6) rat spinal cord. Prolonged focal application of a high concentration of ATP (1 mM) induced a slow inward current. Equimolar concentrations of BzATP generated larger currents that reversed close to 0 mV, had a linear current–voltage relationship and were blocked by Brilliant Blue G, suggesting the presence of functional P2X7 receptors. Immunohistochemistry showed that P2X7 receptors were expressed around the CC and the processes of RG. BzATP also generated Ca2+ waves in RG that were triggered by Ca2+ influx and propagated via Ca2+ release from internal stores through activation of ryanodine receptors. We speculate that the intracellular Ca2+ signalling triggered by P2X7 receptor activation may be an epigenetic mechanism to modulate the behaviour of progenitors in response to ATP released after injury.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Göritz C, Frisén J (2012) Neural stem cells and neurogenesis in the adult. Cell Stem Cell 10:657–659. doi:10.1016/j.stem.2012.04.005
Marichal N, García G, Radmilovich M et al (2012) Spatial domains of progenitor-like cells and functional complexity of a stem cell niche in the neonatal rat spinal cord. Stem Cells 30:2020–2031. doi:10.1002/stem.1175
Meletis K, Barnabé-Heider F, Carlén M et al (2008) Spinal cord injury reveals multilineage differentiation of ependymal cells. PLoS Biol 6:1494–1507. doi:10.1371/journal.pbio.0060182
Petit A, Sanders AD, Kennedy TE et al (2011) Adult spinal cord radial glia display a unique progenitor phenotype. PLoS One 6, e24538. doi:10.1371/journal.pone.0024538
Marichal N, Garcia G, Radmilovich M et al (2009) Enigmatic central canal contacting cells: immature neurons in “standby mode”? J Neurosci 29:10010–10024. doi:10.1523/JNEUROSCI.6183-08.2009
Barnabé-Heider F, Göritz C, Sabelström H et al (2010) Origin of new glial cells in intact and injured adult spinal cord. Cell Stem Cell 7:470–482. doi:10.1016/j.stem.2010.07.014
Sabelström H, Stenudd M, Réu P et al (2013) Resident neural stem cells restrict tissue damage and neuronal loss after spinal cord injury in mice. Science 342:637–640. doi:10.1126/science.1242576
Weissman TA, Riquelme PA, Ivic L et al (2004) Calcium waves propagate through radial glial cells and modulate proliferation in the developing neocortex. Neuron 43:647–661
Zimmermann H (2006) Nucleotide signalling in nervous system development. Pflugers Arch 452:573–588
Di Virgilio F, Boeynaems JM, Robson SC (2009) Extracellular nucleotides as negative modulators of immunity. Curr Opin Pharmacol 9:507–513. doi:10.1016/j.coph.2009.06.02
Khakh BS, North RA (2006) P2X receptors as cell-surface ATP sensors in health and disease. Nature 442:527–532
Surprenant A, North RA (2009) Signaling at purinergic P2X receptors. Annu Rev Physiol 71:333–359. doi:10.1146/annurev.physiol.70.113006.100630
Abbracchio MP, Burnstock G, Verkhratsky A et al (2009) Purinergic signalling in the nervous system: an overview. Trends Neurosci 32:19–29. doi:10.1016/j.tins.2008.10.001
Wang X, Arcuino G, Takano T et al (2004) P2X7 receptor inhibition improves recovery after spinal cord injury. Nat Med 10:821–827
Peng W, Cotrina ML, Han X et al (2009) Systemic administration of an antagonist of the ATP-sensitive receptor P2X7 improves recovery after spinal cord injury. Proc Natl Acad Sci U S A 106:12489–12493. doi:10.1073/pnas.0902531106
Barry PH, Diamond JM (1970) Junction potentials, electrode standard potentials, and other problems in interpreting electrical properties in membranes. J Membr Biol 3:93–122. doi:10.1007/BF01868010
Stoeckel ME, Uhl-Bronner S, Hugel S et al (2003) Cerebrospinal fluid-contacting neurons in the rat spinal cord, a gamma-aminobutyric acidergic system expressing the P2X2 subunit of purinergic receptors, PSA-NCAM, and GAP-43 immunoreactivities: light and electron microscopic study. J Comp Neurol 457:159–174
North RA (2002) Molecular physiology of P2X receptors. Physiol Rev 82:1013–1067
Hamilton LK, Truong MK, Bednarczyk MR et al (2009) Cellular organization of the central canal ependymal zone, a niche of latent neural stem cells in the adult mammalian spinal cord. Neuroscience 164:1044–1056. doi:10.1016/j.neuroscience.2009.09.006
Bianchi BR, Lynch KJ, Touma E et al (1999) Pharmacological characterization of recombinant human and rat P2X receptor subtypes. Eur J Pharmacol 376:127–138
North RA, Surprenant A (2000) Pharmacology of cloned P2X receptors. Annu Rev Pharmacol Toxicol 40:563–80
Anderson CM, Nedergaard M (2006) Emerging challenges of assigning P2X7 receptor function and immunoreactivity in neurons. Trends Neurosci 29:257–262
Jiang LH, Baldwin JM, Roger S et al (2013) Insights into the molecular mechanisms underlying mammalian P2X7 receptor functions and contributions in diseases, revealed by structural modeling and single nucleotide polymorphisms. Front Pharmacol 4:55. doi:10.3389/fphar.2013.00055
Evans RJ, Lewis C, Buell G et al (1995) Pharmacological characterization of heterologously expressed ATP-gated cation channels (P2X purinoceptors). Mol Pharmacol 48:178–183
Jiang LH, Mackenzie AB, North RA et al (2000) Brilliant blue G selectively blocks ATP-gated rat P2X7 receptors. Mol Pharmacol 58:82–88
Yu Y, Ugawa S, Ueda T et al (2008) Cellular localization of P2X7 receptor mRNA in the rat brain. Brain Res 1194:45–55. doi:10.1016/j.brainres.2007.11.064
Genzen JR, Platel JC, Rubio ME et al (2009) Ependymal cells along the lateral ventricle express functional P2X(7) receptors. Purinergic Signal 5:299–307. doi:10.1007/s11302-009-9143-5
Cornell-Bell AH, Finkbeiner SM, Cooper MS et al (1990) Glutamate induces calcium waves in cultured astrocytes: long-range glial signalling. Science 247:470–473
Clapham DE (1995) Calcium signalling. Cell 80:259–268
Berridge MJ, Lipp P, Bootman MD (2000) The versatility and universality of calcium signalling. Nat Rev Mol Cell Biol 1:11–21
Iino M (2010) Spatiotemporal dynamics of Ca2+ signalling and its physiological roles. Proc Jpn Acad Ser B Phys Biol Sci 86:244–256
Franke H, Krügel U, Illes P (2006) P2 receptors and neuronal injury. Pflugers Arch 452:622–644
Glaser T, Resende RR, Ulrich H (2013) Implications of purinergic receptor-mediated intracellular calcium transients in neural differentiation. Cell Commun Signal 11:12. doi:10.1186/1478-811X-11-12
Miras-Portugal MT, Gomez-Villafuertes R, Gualix J, Diaz-Hernandez JI, Artalejo AR, Ortega F, Delicado EG, Perez-Sen R (2015) Nucleotides in neuroregeneration and neuroprotection. Neuropharmacology. doi:10.1016/j.neuropharm.2015.09.002
Liu X, Hashimoto-Torii K, Torii M et al (2008) The role of ATP signalling in the migration of intermediate neuronal progenitors to the neocortical subventricular zone. Proc Natl Acad Sci U S A 105:11802–11807. doi:10.1073/pnas.0805180105
Fietz SA, Huttner WB (2011) Cortical progenitor expansion, self-renewal and neurogenesis—a polarized perspective. Curr Opin Neurobiol 21:23–35. doi:10.1016/j.conb.2010.10.002
Alvarez-Buylla A, García-Verdugo JM, Tramontin AD (2001) A unified hypothesis on the lineage of neural stem cells. Nat Rev Neurosci 2:287–293
Götz M, Huttner WB (2005) The cell biology of neurogenesis. Nat Rev Mol Cell Biol 6:777–788
Goto H, Inoko A, Inagaki M (2013) Cell cycle progression by the repression of primary cilia formation in proliferating cells. Cell Mol Life Sci 70:3893–3905. doi:10.1007/s00018-013-1302-8
Corns LF, Atkinson L, Daniel J et al (2015) Cholinergic enhancement of cell proliferation in the postnatal neurogenic niche of the mammalian spinal cord. Stem Cells 33:2864–76. doi:10.1002/stem.2077
Gómez-Villafuertes R, Rodríguez-Jiménez FJ, Alastrue-Agudo A et al (2015) Purinergic receptors in spinal cord-derived ependymal stem/progenitor cells and its potential role in cell-based therapy for spinal cord injury. Cell Transplant 24:1493–509. doi:10.3727/096368914X682828
This work was supported by grants FCE 2369 and FCE 100411 from ANII to N.M., and grants FCE 103356 from ANII and R01NS048255 from the National Institute of Neurological Disorders and Stroke to R.E.R. N.M. was a recipient of an ANII fellowship. The antibody rat-401 developed by S. Hockfield was obtained from the Developmental Studies Hybridoma Bank developed under the auspices of the NICHD and maintained by The University of Iowa, Department of Biology, Iowa City, IA 52242.
Conflict of interest
The authors declare that they have no conflicts of interest.
All procedures performed in this study involving animals were in accordance with the ethical standards of the local Committee for Animal Care and Research at the Instituto de Investigaciones Biológicas Clemente Estable. Every precaution was taken to minimize animal stress and the number of animals used.
About this article
Cite this article
Marichal, N., Fabbiani, G., Trujillo-Cenóz, O. et al. Purinergic signalling in a latent stem cell niche of the rat spinal cord. Purinergic Signalling 12, 331–341 (2016). https://doi.org/10.1007/s11302-016-9507-6
- Stem cells
- Purinergic signalling
- P2X7 receptors
- Ca2+ waves
- Spinal cord