In FY2008, the lab setup was completed, and the section now has four people including the PI. We presented three posters in two meetings: Two in the Neuroscience Meeting held at San Deigo CA, and one in the zebrafish meeting held at Madison WI. ? We published one review article entitled """"""""Emerging picture of synapse formation: A balance of two opposing pathways"""""""" in the journal """"""""Science Signaling"""""""". The abstract is as follows: The neuromuscular junction (NMJ) is a well-studied chemical synapse and has served as a tractable model system to clarify how synapse formation occurs. Proteins on both the presynaptic and postsynaptic side collaborate to induce the high-density accumulation of acetylcholine receptors (AChRs) at the NMJ. Two opposing pathways work in this process: A dispersing pathway works through acetylcholine and the AChR and a clustering pathway works through agrin and the transmembrane tyrosine kinase MuSK. The molecular mechanisms underlying these two signaling cascades are beginning to be understood. ? We also submitted a paper entitled """"""""Modified acetylcholine receptor subunit enables a null mutant to survive beyond the sexual maturation"""""""" to the Journal of Neuroscience. The manuscript received a favorable review and is under revision now. The abstract is as follows: The contraction of skeletal muscle is dependent upon the synaptic transmission through acetylcholine receptors (AChRs) at the neuromuscular junction (NMJ). The lack of an AChR subunit causes a fetal akinesia in humans, leading to death in the first trimester with characteristic features of Fetal Akinesia Deformation Sequences (FADS). A corresponding null mutation of the -subunit in zebrafish (sofa potato; sop-/-) leads to the death of embryos around 5 days post-fertilization (dpf). In sop-/- mutants, we expressed modified -subunits, with one (1YFP) or two yellow fluorescent protein (2YFP) molecules fused at the intracellular loop. AChRs containing these fusion proteins are fluorescent, assemble on the plasma membrane, make clusters under motor neuron endings, and generate synaptic current. We screened for germ-line transmission of the transgene and established a stably-rescued line of sop-/-. These 2YFP/sop-/- embryos can mount escape behavior close to wild type siblings. Synaptic currents in these embryos had a smaller amplitude, slower rise time, and slower decay when compared to wild type fish. Remarkably, these embryos grow to adulthood and display normal locomotion, including such complex behaviors as feeding and breeding. To the best of our knowledge, this is the first case of a mutant animal corresponding to first trimester lethality in human that has been rescued by a transgene and survived to adulthood. Altered synaptic strength resulting from the transgene delineates requirements for gene therapies of NMJ.
| Ono, Fumihito (2008) An emerging picture of synapse formation: a balance of two opposing pathways. Sci Signal 1:pe3 |
