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西亚试剂:Histone H2AX-dependent GABAA receptor regulation of stem ce

Histone H2AX-dependent GABAA receptor regulation of stem cell proliferation

Michael Andäng1, Jens Hjerling-Leffler1, Annalena Moliner2, T. Kalle Lundgren1, Gonçalo Castelo-Branco3, Evanthia Nanou2, Ester Pozas1, Vitezslav Bryja1,7, Sophie Halliez5, Hiroshi Nishimaru2, Johannes Wilbertz4, Ernest Arenas1, Martin Koltzenburg6, Patrick Charnay5, Abdeljabbar El Manira2, Carlos F. Ibañez2 & Patrik Ernfors1

  1. Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics,
  2. Department of Neuroscience,
  3. Laboratory of Molecular Neurodevelopment, Department of Neuroscience,
  4. Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden
  5. INSERM, U 784, École Normale Supérieure, 75230 Paris Cedex 05, France
  6. Neural Plasticity Unit, Institute of Child Health, University College London, London WCIE 6BT, UK
  7. Present address: Institute of Biophysics Academy of Sciences of the Czech Republic and Institute of Experimental Biology, Faculty of Science, Masaryk University, 603 65 Brno, Czech Republic.

Correspondence to: Patrik Ernfors1 Correspondence and requests for materials should be addressed to P.E. (Email: patrik.ernfors@ki.se).

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Stem cell self-renewal implies proliferation under continued maintenance of multipotency. Small changes in numbers of stem cells may lead to large differences in differentiated cell numbers, resulting in significant physiological consequences. Proliferation is typically regulated in the G1 phase, which is associated with differentiation and cell cycle arrest1. However, embryonic stem (ES) cells may lack a G1 checkpoint2, 3. Regulation of proliferation in the 'DNA damage' S/G2 cell cycle checkpoint pathway is known for its role in the maintenance of chromatin structural integrity4. Here we show that autocrine/paracrine gamma-aminobutyric acid (GABA) signalling by means of GABAA receptors negatively controls ES cell and peripheral neural crest stem (NCS) cell proliferation, preimplantation embryonic growth and proliferation in the boundary-cap stem cell niche, resulting in an attenuation of neuronal progenies from this stem cell niche. Activation of GABAA receptors leads to hyperpolarization, increased cell volume and accumulation of stem cells in S phase, thereby causing a rapid decrease in cell proliferation. GABAA receptors signal through S-phase checkpoint kinases of the phosphatidylinositol-3-OH kinase-related kinase family and the histone variant H2AX. This signalling pathway critically regulates proliferation independently of differentiation, apoptosis and overt damage to DNA. These results indicate the presence of a fundamentally different mechanism of proliferation control in these stem cells, in comparison with most somatic cells, involving proteins in the DNA damage checkpoint pathway.