The role of remote astrocyte (AC) reaction to central or peripheral axonal insult is not clearly understood. Here we use a transgenic approach to compare the direct influence of normal with diminished AC reactivity on neuronal integrity and synapse recovery following extracranial facial nerve transection in mice. Our model allows straightforward interpretations of AC-neuron signalling by reducing confounding effects imposed by inflammatory cells. We show direct evidence that perineuronal reactive ACs play a major role in maintaining neuronal circuitry following distant axotomy. We reveal a novel function of astrocytic signal transducer and activator of transcription-3 (STAT3). STAT3 regulates perineuronal astrocytic process formation and re-expression of a synaptogenic molecule, thrombospondin-1 (TSP-1), apart from supporting neuronal integrity. We demonstrate that, through this new pathway, TSP-1 is responsible for the remote AC-mediated recovery of excitatory synapses onto axotomized motor neurons in adult mice. These data provide new targets for neuroprotective therapies via optimizing AC-driven plasticity.
|Publication status||Published - 11 Jul 2014|
Bibliographical noteFunding Information:
This work has been mainly supported by the Walker Fellowship (A.L.) at the University of Cambridge and by the Van Geest Fund (G.E.T.). We also received personal support by the Gates Scholarship (D.B., S.S.) and the Wellcome Trust Biomedical Vacation Scholarship (N.K.L., A.L.; RG60754). The authors are also grateful to Dr A. Tolkovsky for reading the manuscript and for her useful comments. We are grateful to Professor M. Sofroniew (UCLA, USA) for his advice and providing the STAT3-GFAP-CKO mice and to Professor G. Raivich for commenting on our work. We thank Dr C. Eroglu for the availability of the puncta analyzer software for synapse analysis (developed by B. Wark in Professor B. Barres’ laboratory) and to Dr J. Skepper for the help with electron microscopy.