Our studies of mutant zebrafish continue to advance understanding of synaptic transmission and inheritable forms of human neuromuscular disorders such as myasthenic syndrome, slow channel syndrome and Brody disease. The proposed studies now capitalize on mutant lines which we have shown either lack synaptic transmission altogether, or lack the ability of receptors to localize subsynaptically, the ability of muscle to release calcium, the ability of muscle to sequester calcium, or possess abnormal levels of synaptic drive suggesting miscommunication between presynaptic nerve and postsynaptic muscle. Exploiting the advantages provided by these lines, we will determine the role of synaptic activity in shaping both presynaptic and postsynaptic development. These studies will be greatly facilitated by use of our recently developed tethered toxin methodology that silences synaptic transmission in a cell autonomous fashion. Thus, we can determine the consequences of adjusting synaptic drive and/or excitability of individual cells within the motorneuron target field. Rescue of individual postsynaptic cells in mutant lines will provide a complementary approach wherein a single cell is rendered active in an otherwise silent field of target muscle. This combination of approaches will be used to determine the involvement of postsynaptic activity in the developmental loss of electrical coupling, acquisition of presynaptic transmitter release properties and establishment of postsynaptic receptor kinetics. The study is possible by virtue of our ability, for the first time in any vertebrate preparation, to simultaneously record from a motorneuron and target muscle in vivo. This is due to electrically compact muscle that allows whole cell voltage clamp and transparency, facilitating identification and patch clamp of motorneurons deep within the spinal cord. The combined advantages of new approaches and preparation now provide unique opportunities or examining long standing questions of synaptic function.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37NS018205-32
Application #
8099557
Study Section
Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
Program Officer
Porter, John D
Project Start
2007-06-01
Project End
2013-07-31
Budget Start
2011-08-01
Budget End
2013-07-31
Support Year
32
Fiscal Year
2011
Total Cost
$353,453
Indirect Cost
Name
Oregon Health and Science University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Wen, Hua; Linhoff, Michael W; Hubbard, Jeffrey M et al. (2013) Zebrafish calls for reinterpretation for the roles of P/Q calcium channels in neuromuscular transmission. J Neurosci 33:7384-92
Walogorsky, Michael; Mongeon, Rebecca; Wen, Hua et al. (2012) Acetylcholine receptor gating in a zebrafish model for slow-channel syndrome. J Neurosci 32:7941-8
Hirata, Hiromi; Wen, Hua; Kawakami, Yu et al. (2012) Connexin 39.9 protein is necessary for coordinated activation of slow-twitch muscle and normal behavior in zebrafish. J Biol Chem 287:1080-9
Mongeon, Rebecca; Walogorsky, Michael; Urban, Jason et al. (2011) An acetylcholine receptor lacking both ýý and ýý subunits mediates transmission in zebrafish slow muscle synapses. J Gen Physiol 138:353-66
Wen, Hua; Brehm, Paul (2010) Paired patch clamp recordings from motor-neuron and target skeletal muscle in zebrafish. J Vis Exp :
Wen, Hua; Linhoff, Michael W; McGinley, Matthew J et al. (2010) Distinct roles for two synaptotagmin isoforms in synchronous and asynchronous transmitter release at zebrafish neuromuscular junction. Proc Natl Acad Sci U S A 107:13906-11
Wang, Meng; Wen, Hua; Brehm, Paul (2008) Function of neuromuscular synapses in the zebrafish choline-acetyltransferase mutant bajan. J Neurophysiol 100:1995-2004
Mongeon, Rebecca; Gleason, Michelle R; Masino, Mark A et al. (2008) Synaptic homeostasis in a zebrafish glial glycine transporter mutant. J Neurophysiol 100:1716-23
Luna, Victor M; Brehm, Paul (2006) An electrically coupled network of skeletal muscle in zebrafish distributes synaptic current. J Gen Physiol 128:89-102
Wen, Hua; Brehm, Paul (2005) Paired motor neuron-muscle recordings in zebrafish test the receptor blockade model for shaping synaptic current. J Neurosci 25:8104-11

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