|ZFIN ID: ZDB-PUB-081217-4|
A modified acetylcholine receptor delta-subunit enables a null mutant to survive beyond sexual maturation
Epley, K.E., Urban, J.M., Ikenaga, T., and Ono, F.
|Source:||The Journal of neuroscience : the official journal of the Society for Neuroscience 28(49): 13223-13231 (Journal)|
|Registered Authors:||Ono, Fumihito, Urban, Jason|
|Keywords:||zebrafish, neuromuscular junction, acetylcholine receptor, synapse, fetal akinesia deformation sequence, fluorescent protein|
|PubMed:||19052214 Full text @ J. Neurosci.|
Epley, K.E., Urban, J.M., Ikenaga, T., and Ono, F. (2008) A modified acetylcholine receptor delta-subunit enables a null mutant to survive beyond sexual maturation. The Journal of neuroscience : the official journal of the Society for Neuroscience. 28(49):13223-13231.
ABSTRACTThe contraction of skeletal muscle is dependent on 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 and characteristic features of Fetal Akinesia Deformation Sequences (FADS). A corresponding null mutation of the delta-subunit in zebrafish (sofa potato; sop) leads to the death of embryos around 5 d postfertilization (dpf). In sop(-/-) mutants, we expressed modified delta-subunits, with one (delta1YFP) or two yellow fluorescent protein (delta2YFP) molecules fused at the intracellular loop, under the control of an alpha-actin promoter. 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 line of sop(-/-) fish stably expressing the delta2YFP. These delta2YFP/sop(-/-) embryos can mount escape behavior close to that of their wild-type siblings. Synaptic currents in these embryos had a smaller amplitude, slower rise time, and slower decay when compared with wild-type fish. Remarkably, these embryos grow to adulthood and display complex behaviors such 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. In the rescued fish, a foreign promoter drove the transgene expression and the NMJ had altered synaptic strength. The survival of the transgenic animal delineates requirements for gene therapies of NMJ.