Gap junctional coupling of radial glia-like precursor cells in the adult dentate gyrus

In the adult dentate gyrus (DG), one of the neurogenic regions in the mature brain, cells with a radial glia (RG)-like morphology represent the putative stem cells that can give rise to new neurons and glial cells. In the course of neurogenesis, RG-like cells divide to generate precursors expressing immature neuronal features. Epileptic seizures or ischemic insults strongly enhance the proliferative activity of RG-like cells while neuronal precursors are less affected. However, the reasons for the different sensitivity of these cell types to pathological insults are poorly understood. In contrast to precursors that are committed to a neuronal fate, RG-like cells apparently do not receive synaptic input. Therefore, alternative environmental cues must be involved in the control of proliferation and differentiation of RG-like cells in the DG. In the present study, we combined patch clamp analysis, biocytin filling and single cell rt-PCR to test whether RG-like cells are coupled through gap junctions. To identify RG-like cells in situ, two different transgenic mice models were used, expressing EGFP under the control of the nestin and GFAP promoters, respectively. We provide evidence that 60–75% of RG-like cells display gap junctional coupling and predominantly express the astrocytic gap junction protein, CX43. In contrast, no coupling was observed between nestin/EGFP positive precursor cells already expressing neuronal properties. Future work has to unravel whether gap junctional coupling of RG-like precursors may serve a role in modulating their proliferative activity. Supported by DFG (SFB/TR3, SE 774/3) and IZKF Jena (TP 1.7).