Neuron-to-glia signaling mediated by excitatory amino acid receptors regulates ErbB receptor function in astroglial cells of the neuroendocrine brain.
Hypothalamic astroglial erbB tyrosine kinase receptors are required for the timely initiation of mammalian puberty. Ligand-dependent activation of these receptors sets in motion a glia-to-neuron signaling pathway that prompts the secretion of luteinizing hormone-releasing hormone (LHRH), the neuropeptide controlling sexual development, from hypothalamic neuroendocrine neurons. The neuronal systems that may regulate this growth factor-mediated back signaling to neuroendocrine neurons have not been identified. Here we demonstrate that hypothalamic astrocytes contain metabotropic receptors of the metabotropic glutamate receptor 5 subtype and the AMPA receptor subunits glutamate receptor 2 (GluR2) and GluR3. As in excitatory synapses, these receptors are in physical association with their respective interacting/clustering proteins Homer and PICK1. In addition, they are associated with erbB-1 and erbB-4 receptors. Concomitant activation of astroglial metabotropic and AMPA receptors results in the recruitment of erbB tyrosine kinase receptors and their respective ligands to the glial cell membrane, transactivation of erbB receptors via a mechanism requiring metalloproteinase activity, and increased erbB receptor gene expression. By facilitating erbB-dependent signaling and promoting erbB receptor gene expression in astrocytes, a neuron-to-glia glutamatergic pathway may represent a basic cell-cell communication mechanism used by the neuroendocrine brain to coordinate the facilitatory transsynaptic and astroglial input to LHRH neurons during sexual development.
Dziedzic
Barbara
B
Division of Neuroscience, Oregon National Primate Research Center/Oregon Health & Science University, Beaverton, Oregon 97006, USA.
Prevot
Vincent
V
Lomniczi
Alejandro
A
Jung
Heike
H
Cornea
Anda
A
Ojeda
Sergio R
SR
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D000072233:Homer Scaffolding Proteins; D007031:Hypothalamus / Q000166:cytology; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D009490:Neurosecretory Systems / Q000166:cytology / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D066247:Receptor, ErbB-4; D064529:Receptor, Metabotropic Glutamate 5; D018091:Receptors, AMPA / Q000096:biosynthesis / Q000235:genetics; D017470:Receptors, Glutamate / Q000235:genetics / Q000378:metabolism*; D018094:Receptors, Metabotropic Glutamate / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*
D002352:Carrier Proteins; D066246:ErbB Receptors; D000072233:Homer Scaffolding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D066247:Receptor, ErbB-4; D064529:Receptor, Metabotropic Glutamate 5; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D018094:Receptors, Metabotropic Glutamate; C491308:Grip1 protein, rat; C104723:glutamate receptor ionotropic, AMPA 3; C587691:Erbb4 protein, rat; C104722:glutamate receptor ionotropic, AMPA 2