Despite the great advances made in our understanding of synapse development at the neuromuscular junction, the roles of several key proteins remain unclear. The proposed experiments will use the unique advantages offered by zebrafish genetics and development to identify the roles of rapsyn, acetylcholine receptor, MuSK and beta-dystroglycan in synapse formation in vivo. Zebrafish offers tremendous advantages over mammalian in vitro and in vivo systems. Studies using in vitro mammalian expression systems and cultured myotubes have both been hampered by the inability to study bona-fide synapses. The in vivo studies have been limited by the inability of the mouse knock-outs to survive through the period of synapse formation. In the case of receptor knock-out, for example, the consequences are so severe that no studies have been able to address the consequences of receptor-less development. By contrast, functional knock-outs of acetylcholine receptor, rapsyn, and MuSK have been identified in mutant lines of zebrafish. These fish were originally identified on the basis of swimming abnormalities that reflect direct consequences of knock-outs of each of these key synaptic proteins. This analysis is possible in zebrafish because, unlike their mammalian counterparts, these mutant animals die well after synapse formation is completed and the animal behavior can be assessed. To date our findings have revealed most unexpected roles for the acetylcholine receptor and for rapsyn in governing synapse development and function. In particular, we have found that the receptor likely plays a key role in localizing rapsyn to the synapse and rapsyn plays a critical role in regulating receptor function. Additionally, our studies have provided new predictions for human neuromuscular diseases, one of which has been confirmed on patients afflicted with rare forms of myasthenia gravis. We are confident that this model system will, through its many unique advantages, resolve some of the outstanding paradoxes involving the roles of signaling molecules in synapse formation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS045935-01A1
Application #
6726989
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Talley, Edmund M
Project Start
2003-09-30
Project End
2007-06-30
Budget Start
2003-09-30
Budget End
2004-06-30
Support Year
1
Fiscal Year
2003
Total Cost
$243,622
Indirect Cost
Name
State University New York Stony Brook
Department
Other Basic Sciences
Type
Schools of Arts and Sciences
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Ono, Fumihito; Mandel, Gail; Brehm, Paul (2004) Acetylcholine receptors direct rapsyn clusters to the neuromuscular synapse in zebrafish. J Neurosci 24:5475-81
Luna, Victor M; Wang, Meng; Ono, Fumihito et al. (2004) Persistent electrical coupling and locomotory dysfunction in the zebrafish mutant shocked. J Neurophysiol 92:2003-9