Nerve Terminal Withdrawal from Rat Neuromuscular Junctions Induced by Neuregulin and Schwann Cells

Schwann cells (SCs) that cap neuromuscular junctions (nmjs) play roles in guiding nerve terminal growth in paralyzed and partially denervated muscles; however, the role of these cells in the day-to-day maintenance of this synapse is obscure. Neuregulins, alternatively spliced ligands for several erbB receptor tyrosine kinases, are thought to play important roles in cell–cell communication at the nmj, affecting synapse-specific gene expression in muscle fibers and the survival of terminal SCs during development. Here we show that application of a soluble neuregulin isoform, glial growth factor II (GGF2), to developing rat muscles alters terminal SCs, nerve terminals, and muscle fibers. SCs extend processes and migrate from the synapse. Nerve terminals retract from acetylcholine receptor-rich synaptic sites, and their axons grow, in association with SCs, to the ends of the muscle. These axons make effective synapses only after withdrawal of GGF2. These synaptic alterations appear to be induced by the actions of neuregulin on SCs, because SC transplants growing into contact with synaptic sites also caused withdrawal of nerve terminal branches. These results show that SCs can alter synaptic structure at the nmj and implicate these cells in the maintenance of this synapse.

[1]  C. Slater.  Neural influence on the postnatal changes in acetylcholine receptor distribution at nerve-muscle junctions in the mouse. , 1982, Developmental biology.

[2]  J. Sanes,et al.  Synapse-associated expression of an acetylcholine receptor-inducing protein, ARIA/heregulin, and its putative receptors, ErbB2 and ErbB3, in developing mammalian muscle. , 1995, Developmental biology.

[3]  M. Sliwkowski,et al.  Axon-induced mitogenesis of human Schwann cells involves heregulin and p185erbB2. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[4]  M. Waterfield,et al.  Glial growth factors are alternatively spliced erbB2 ligands expressed in the nervous system , 1993, Nature.

[5]  M. Sliwkowski,et al.  Coexpression of erbB2 and erbB3 proteins reconstitutes a high affinity receptor for heregulin. , 1994, The Journal of biological chemistry.

[6]  J. Lichtman,et al.  Motor nerve terminal loss from degenerating muscle fibers , 1989, Neuron.

[7]  J. Changeux,et al.  ErbB3 and ErbB2/neu mediate the effect of heregulin on acetylcholine receptor gene expression in muscle: differential expression at the endplate. , 1995, The EMBO journal.

[8]  S. Scherer,et al.  Axonal Interactions Regulate Schwann Cell Apoptosis in Developing Peripheral Nerve: Neuregulin Receptors and the Role of Neuregulins , 1996, The Journal of Neuroscience.

[9]  Jeff W. Lichtman,et al.  Gradual loss of synaptic cartels precedes axon withdrawal at developing neuromuscular junctions , 1993, Neuron.

[10]  D. Riley.  Ultrastructural evidence for axon retraction during the spontaneous elimination of polyneuronal innervation of the rat soleus muscle , 1981, Journal of neurocytology.

[11]  D. Purves,et al.  Neuron/glia relationships observed over intervals of several months in living mice , 1988, The Journal of cell biology.

[12]  U J McMahan,et al.  Reinnervation of muscle fiber basal lamina after removal of myofibers. Differentiation of regenerating axons at original synaptic sites , 1978, The Journal of cell biology.

[13]  G. Fischbach,et al.  The number of Na+ channels in cultured chick muscle is increased by ARIA, an acetylcholine receptor-inducing activity , 1993, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[14]  T. Reh,et al.  Effects of GGF/neuregulins on neuronal survival and neurite outgrowth correlate with erbB2/neu expression in developing rat retina. , 1996, Development.

[15]  Jeff W. Lichtman,et al.  Long-term synapse loss induced by focal blockade of postsynaptlc receptors , 1994, Nature.

[16]  M. Smith,et al.  Identification of agrin, a synaptic organizing protein from Torpedo electric organ , 1987, The Journal of cell biology.

[17]  P. Distefano,et al.  Agrin Acts via a MuSK Receptor Complex , 1996, Cell.

[18]  J. Molgó,et al.  The levator auris longus muscle of the mouse: A convenient preparation for studies of short- and long-term presynaptic effects of drugs or toxins , 1987, Neuroscience Letters.

[19]  J. Jansen,et al.  The extent of sprouting of remaining motor units in partly denervated immature and adult rat soleus muscle , 1977, Neuroscience.

[20]  G. Fischbach,et al.  Acetylcholine receptor-inducing factor from chicken brain increases the level of mRNA encoding the receptor alpha subunit. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[21]  M. Sliwkowski,et al.  Regulation of the acetylcholine receptor ϵ subunit gene by recombinant ARIA: An in vitro model for transynaptic gene regulation , 1995, Neuron.

[22]  J. Bixby.  Ultrastructural observations on synapse elimination in neonatal rabbit skeletal muscle , 1981, Journal of neurocytology.

[23]  M. Rich,et al.  In vivo visualization of pre- and postsynaptic changes during synapse elimination in reinnervated mouse muscle , 1989, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[24]  D. Kuffler,et al.  Accurate reinnervation of motor end plates after disruption of sheath cells and muscle fibers , 1986, The Journal of comparative neurology.

[25]  A. Dunaevsky,et al.  Long-term maintenance of presynaptic function in the absence of target muscle fibers , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[26]  P. K. Ko,et al.  Denervated skeletal muscle fibers develop discrete patches of high acetylcholine receptor density. , 1977, Science.

[27]  J. Jansen,et al.  Hyperinnervation of Skeletal Muscle Fibers: Dependence on Muscle Activity , 1973, Science.

[28]  G. Fischbach,et al.  ARIA is concentrated in the synaptic basal lamina of the developing chick neuromuscular junction , 1995, The Journal of cell biology.

[29]  D. V. Essen,et al.  Competition between foreign and original nerves in adult mammalian skeletal muscle , 1979, Nature.

[30]  C. Birchmeier,et al.  Multiple essential functions of neuregulin in development , 1995, Nature.

[31]  J. Bixby,et al.  Agrin is a differentiation-inducing “stop signal” for motoneurons in vitro , 1995, Neuron.

[32]  K. Carraway,et al.  Neuregulins and their receptors , 1995, Current Opinion in Neurobiology.

[33]  L. Cantley,et al.  A neu acquaintance for ErbB3 and ErbB4: A role for receptor heterodimerization in growth signaling , 1994, Cell.

[34]  G. Fischbach,et al.  Acetylcholine receptor-inducing activity stimulates expression of the epsilon-subunit gene of the muscle acetylcholine receptor. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[35]  S. Burden,et al.  Neuregulin receptors, erbB3 and erbB4, are localized at neuromuscular synapses. , 1995, The EMBO journal.

[36]  M. Matthews,et al.  Detachment of structurally intact nerve endings from chromatolytic neurones of rat superior cervical ganglion during the depression of synaptic transmission induced by post‐ganglionic axotomy. , 1975, The Journal of physiology.

[37]  J. Sanes,et al.  Differentiation of motor nerve terminals formed in the absence of muscle fibres , 1983, Journal of neurocytology.

[38]  Kuo-Fen Lee,et al.  Requirement for neuregulin receptor erbB2 in neural and cardiac development , 1995, Nature.

[39]  D. Purves,et al.  Visualization of neuromuscular junctions over periods of several months in living mice , 1987, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[40]  Greg Lemke,et al.  Neuregulins in Development , 1996, Molecular and Cellular Neuroscience.

[41]  J. Sanes,et al.  Defective Neuromuscular Synaptogenesis in Agrin-Deficient Mutant Mice , 1996, Cell.

[42]  U J McMahan,et al.  Reinnervation of original synaptic sites on muscle fiber basement membrane after disruption of the muscle cells. , 1977, Proceedings of the National Academy of Sciences of the United States of America.

[43]  C. Woolf,et al.  Terminal Schwann cells elaborate extensive processes following denervation of the motor endplate , 1992, Journal of neurocytology.

[44]  J. Rusche,et al.  Schwann cell heparan sulfate proteoglycans play a critical role in glial growth factor/neuregulin signaling , 1996, Glia.

[45]  M. Sliwkowski,et al.  Regulation of the acetylcholine receptor epsilon subunit gene by recombinant ARIA: an in vitro model for transynaptic gene regulation. , 1995, Neuron.

[46]  J. Cohen,et al.  Expression of the neu proto‐oncogene by schwann cells during peripheral nerve development and wallerian degeneration , 1992, Journal of neuroscience research.

[47]  I. Fariñas,et al.  A Reciprocal Cell–Cell Interaction Mediated by NT-3 and Neuregulins Controls the Early Survival and Development of Sympathetic Neuroblasts , 1996, Neuron.

[48]  J. Lichtman,et al.  In vivo observations of pre- and postsynaptic changes during the transition from multiple to single innervation at developing neuromuscular junctions , 1993, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[49]  B. Katz,et al.  Quantal components of the end‐plate potential , 1954, The Journal of physiology.

[50]  J. Lichtman,et al.  Alterations in Synaptic Strength Preceding Axon Withdrawal , 1997, Science.

[51]  J. Sanes,et al.  Aberrant differentiation of neuromuscular junctions in mice lacking s-laminin/laminin β2 , 1995, Nature.

[52]  P. Distefano,et al.  The Receptor Tyrosine Kinase MuSK Is Required for Neuromuscular Junction Formation In Vivo , 1996, Cell.

[53]  A. W. Liley,et al.  The quantal components of the mammalian end‐plate potential , 1956, The Journal of physiology.

[54]  P. van Mier,et al.  Regenerating muscle fibers induce directional sprouting from nearby nerve terminals: studies in living mice , 1994, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[55]  W. Thompson,et al.  Nerve sprouting in muscle is induced and guided by processes extended by schwann cells , 1995, Neuron.

[56]  S. Jo,et al.  Neuregulins are concentrated at nerve-muscle synapses and activate ACh–receptor gene expression , 1995, Nature.

[57]  Rüdiger Klein,et al.  Aberrant neural and cardiac development in mice lacking the ErbB4 neuregulin receptor , 1995, Nature.

[58]  J. Trachtenberg,et al.  Schwann cell apoptosis at developing neuromuscular junctions is regulated by glial growth factor , 1996, Nature.

[59]  L. Rubin,et al.  Components of Torpedo electric organ and muscle that cause aggregation of acetylcholine receptors on cultured muscle cells , 1984, The Journal of cell biology.

[60]  E. Anton,et al.  Glial Growth Factor 2, a Soluble Neuregulin, Directly Increases Schwann Cell Motility and Indirectly Promotes Neurite Outgrowth , 1996, The Journal of Neuroscience.