Glia cell line-derived neurotrophic factor regulates the distribution of acetylcholine receptors in mouse primary skeletal muscle cells.
It was recently reported that glia cell line-derived neurotrophic factor (GDNF) facilitates presynaptic axonal growth and neurotransmitter release at neuromuscular synapses. Little is known, however, whether GDNF can also act on the postsynaptic apparatus and its underlying mechanisms. Using biochemical cold blocking of existing membrane acetylcholine receptors (AchRs) and biotinylation of newly inserted receptors we demonstrate that GDNF increases the insertion of AChRs into the surface membrane of mouse primary cultured muscle cells and that this does not require protein synthesis. Quantitative data from double-label imaging indicate that GDNF induces a quick and substantial increase in AchR insertion as well as lateral movement into AchR aggregates, relative to a weak effect on reducing the loss of receptors from pre-existing AchR aggregates, which in contrast to the effect of PMA. These effects occur in both innervated and un-innervated muscles, and GDNF affects nerve-muscle co-cultures more than it affects muscle-only cultures. Neurturin, another member of GDNF-family ligands has similar effects on AchRs as GDNF but the unrelated growth factor, EGF does not. Studies on protein phosphorylation and specific inhibitors of cell signal transduction indicate that GDNF function is mediated by receptor GFRalpha1 and involves MAPK, cAMP/cAMP responsive element-binding factor and Src kinase activities. GDNF may signal through c-Ret as well as NCAM-140 pathways since both the signaling receptors are expressed in the neuromuscular junction (NMJ). These data suggest that GDNF is an autocrine regulator of NMJ to promote the insertion and stabilization of postsynaptic AchRs. In vivo, GDNF may function as a synaptotrophic modulator for both pre- and postsynaptic differentiation to strengthen the functional and structural connections between nerve and muscle, and contribute to the synaptogenesis and plasticity of neuromuscular synapses.
Yang
L-X
LX
Section on Neurobiology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bldg 49, Bethesda, MD 20892, USA. lixia.yang@hgen.pitt.edu
Nelson
P G
PG
D000818:Animals; D000831:Animals, Newborn; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology; D019921:Biotinylation; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000196:embryology / Q000294:innervation*; D009414:Nerve Growth Factors / Q000494:pharmacology / Q000502:physiology*; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D009469:Neuromuscular Junction / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D051101:Neurturin; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051096:Proto-Oncogene Proteins c-ret; D011940:Receptor Aggregation / Q000187:drug effects* / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000378:metabolism*; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D019061:src-Family Kinases / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; C495040:Gdnf protein, mouse; C494988:Gfra1 protein, mouse; D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D009414:Nerve Growth Factors; D019006:Neural Cell Adhesion Molecules; D051101:Neurturin; C495056:Nrtn protein, mouse; D011518:Proto-Oncogene Proteins; D011950:Receptors, Cholinergic; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C494999:Ret protein, mouse; D019061:src-Family Kinases