Connexin expression by radial glia-like cells is required for neurogenesis in the adult dentate gyrus

In the adult dentate gyrus, radial glia-like cells represent putative stem cells generating neurons and glial cells. Here, we combined patch-clamp recordings, biocytin filling, immunohistochemistry, single-cell transcript analysis, and mouse transgenics to test for connexin expression and gap junctional coupling of radial glia-like cells and its impact on neurogenesis. Radial glia-like cells were identified in mice expressing EGFP under control of the nestin and gfap promoters. We show that a majority of Radial glia-like cells are coupled and express Cx43. Neuronal precursors were not coupled. Mice lacking Cx30 and Cx43 in GFAP-positive cells displayed almost complete inhibition of proliferation and a significant decline in numbers of radial glia-like cells and granule neurons. Inducible virus-mediated ablation of connexins in the adult hippocampus also reduced neurogenesis. These findings strongly suggest the requirement of connexin expression by radial glia-like cells for intact neurogenesis in the adult brain and point to possible communication pathways of these cells.

[1]  Masahiro Yamaguchi,et al.  Two Distinct Subpopulations of Nestin-Positive Cells in Adult Mouse Dentate Gyrus , 2003, The Journal of Neuroscience.

[2]  A. Kriegstein,et al.  Gap junctions: multifaceted regulators of embryonic cortical development , 2008, Trends in Neurosciences.

[3]  A. Kriegstein,et al.  Cell Coupling and Uncoupling in the Ventricular Zone of Developing Neocortex , 1997, The Journal of Neuroscience.

[4]  M. Mattson,et al.  Gap junctional communication is required to maintain mouse cortical neural progenitor cells in a proliferative state. , 2004, Developmental biology.

[5]  M. Yamaguchi,et al.  Visualization of neurogenesis in the central nervous system using nestin promoter‐GFP transgenic mice , 2000, Neuroreport.

[6]  J. Drijfhout,et al.  Cross-presentation by intercellular peptide transfer through gap junctions , 2005, Nature.

[7]  P. Meda,et al.  Cell coupling and Cx43 expression in embryonic mouse neural progenitor cells. , 2002, Journal of cell science.

[8]  C. Greer,et al.  Dynamic Contribution of Nestin-Expressing Stem Cells to Adult Neurogenesis , 2007, The Journal of Neuroscience.

[9]  H. Kettenmann,et al.  A subpopulation of precursor cells in the mouse dentate gyrus receives synaptic GABAergic input , 2005, Molecular and Cellular Neuroscience.

[10]  P. Meda,et al.  Reduced Expression of P2Y1 Receptors in Connexin43-Null Mice Alters Calcium Signaling and Migration of Neural Progenitor Cells , 2003, The Journal of Neuroscience.

[11]  H. Kettenmann,et al.  Type‐2 cells as link between glial and neuronal lineage in adult hippocampal neurogenesis , 2006, Glia.

[12]  C. Ribak,et al.  GFAP-expressing radial glia-like cell bodies are involved in a one-to-one relationship with doublecortin-immunolabeled newborn neurons in the adult dentate gyrus , 2005, Brain Research.

[13]  A. Kriegstein,et al.  Gap junction adhesion is necessary for radial migration in the neocortex , 2007, Nature.

[14]  F. Kirchhoff,et al.  Seizures preferentially stimulate proliferation of radial glia‐like astrocytes in the adult dentate gyrus: functional and immunocytochemical analysis , 2003, The European journal of neuroscience.

[15]  F. Kirchhoff,et al.  Segregated Expression of AMPA-Type Glutamate Receptors and Glutamate Transporters Defines Distinct Astrocyte Populations in the Mouse Hippocampus , 2003, The Journal of Neuroscience.

[16]  J. García-Verdugo,et al.  Astrocytes Give Rise to New Neurons in the Adult Mammalian Hippocampus , 2001, The Journal of Neuroscience.

[17]  O. Witte,et al.  Proliferative response of distinct hippocampal progenitor cell populations after cortical infarcts in the adult brain , 2006, Neurobiology of Disease.

[18]  P. Carlen,et al.  Changes in Neuronal Migration in Neocortex of Connexin43 Null Mutant Mice , 2003, Journal of neuropathology and experimental neurology.

[19]  B. Sutor,et al.  Involvement of gap junctions in the development of the neocortex. , 2005, Biochimica et biophysica acta.

[20]  J. Loturco,et al.  Differential regulation of connexin 26 and 43 in murine neocortical precursors. , 1999, Cerebral cortex.

[21]  D. Spray,et al.  Connexin43 null mice reveal that astrocytes express multiple connexins , 2000, Brain Research Reviews.

[22]  K. Willecke,et al.  Emerging complexities in identity and function of glial connexins , 2005, Trends in Neurosciences.

[23]  K. Willecke,et al.  Distinct types of astroglial cells in the hippocampus differ in gap junction coupling , 2004, Glia.

[24]  T. Hisatsune,et al.  GABAergic Excitation Promotes Neuronal Differentiation in Adult Hippocampal Progenitor Cells , 2005, Neuron.

[25]  R. McKay,et al.  Adult neurogenesis produces a large pool of new granule cells in the dentate gyrus , 2001, The Journal of comparative neurology.

[26]  U. Heinemann,et al.  Accelerated Hippocampal Spreading Depression and Enhanced Locomotory Activity in Mice with Astrocyte-Directed Inactivation of Connexin43 , 2003, The Journal of Neuroscience.

[27]  C. Naus,et al.  Epileptiform activity in hippocampal slice cultures exposed chronically to bicuculline: increased gap junctional function and expression , 2003, Journal of neurochemistry.

[28]  M. Miller,et al.  Bromodeoxyuridine immunohistochemical determination of the lengths of the cell cycle and the DNA-synthetic phase for an anatomically defined population , 1989, Journal of neurocytology.

[29]  Gerd Kempermann,et al.  Milestones of neuronal development in the adult hippocampus , 2004, Trends in Neurosciences.

[30]  A. E. Wiencken-barger,et al.  A role for Connexin43 during neurodevelopment , 2007, Glia.

[31]  H. Kettenmann,et al.  Subpopulation of nestin-expressing progenitor cells in the adult murine hippocampus shows electrophysiological and morphological characteristics of astrocytes , 2003, Molecular and Cellular Neuroscience.

[32]  H. Kettenmann,et al.  Properties of GABA and glutamate responses in identified glial cells of the mouse hippocampal slice , 1994, Hippocampus.

[33]  Fred H. Gage,et al.  Astroglia induce neurogenesis from adult neural stem cells , 2002, Nature.

[34]  J. García-Verdugo,et al.  Cell types, lineage, and architecture of the germinal zone in the adult dentate gyrus , 2004, The Journal of comparative neurology.

[35]  U. Heinemann,et al.  The Impact of Astrocytic Gap Junctional Coupling on Potassium Buffering in the Hippocampus , 2006, The Journal of Neuroscience.

[36]  Magdalena Götz,et al.  Distinct Modes of Neuron Addition in Adult Mouse Neurogenesis , 2007, The Journal of Neuroscience.

[37]  M. Rosen,et al.  Connexin‐specific cell‐to‐cell transfer of short interfering RNA by gap junctions , 2005, The Journal of physiology.

[38]  Arnold R. Kriegstein,et al.  Calcium Waves Propagate through Radial Glial Cells and Modulate Proliferation in the Developing Neocortex , 2004, Neuron.

[39]  F. Gage,et al.  Experience-Specific Functional Modification of the Dentate Gyrus through Adult Neurogenesis: A Critical Period during an Immature Stage , 2007, The Journal of Neuroscience.