Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants
<p>Abstract</p> <p>Background</p> <p>Sec8 is highly expressed in mammalian nervous systems and has been proposed to play a role in several aspects of neural development and function, including neurite outgrowth, calcium-dependent neurotransmitter secretion, trafficking...
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| Format: | Article |
| Language: | English |
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BMC
2005-12-01
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| Series: | BMC Biology |
| Online Access: | http://www.biomedcentral.com/1741-7007/3/27 |
| _version_ | 1818229255943749632 |
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| author | Sheng Qi Karr Julie Chen Kaiyun Liebl Faith LW Featherstone David E |
| author_facet | Sheng Qi Karr Julie Chen Kaiyun Liebl Faith LW Featherstone David E |
| author_sort | Sheng Qi |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Sec8 is highly expressed in mammalian nervous systems and has been proposed to play a role in several aspects of neural development and function, including neurite outgrowth, calcium-dependent neurotransmitter secretion, trafficking of ionotropic glutamate receptors and regulation of neuronal microtubule assembly. However, these models have never been tested <it>in vivo</it>. Nervous system development and function have not been described after mutation of <it>sec8 </it>in any organism.</p> <p>Results</p> <p>We identified lethal <it>sec8 </it>mutants in an unbiased forward genetic screen for mutations causing defects in development of glutamatergic <it>Drosophila </it>neuromuscular junctions (NMJs). The <it>Drosophila </it>NMJ is genetically malleable and accessible throughout development to electrophysiology and immunocytochemistry, making it ideal for examination of the <it>sec8 </it>mutant synaptic phenotype. We developed antibodies to <it>Drosophila </it>Sec8 and showed that Sec8 is abundant at the NMJ. In our <it>sec8 </it>null mutants, in which the <it>sec8 </it>gene is specifically deleted, Sec8 immunoreactivity at the NMJ is eliminated but immunoblots reveal substantial maternal contribution in the rest of the animal. Contrary to the hypothesis that Sec8 is required for neurite outgrowth or synaptic terminal growth, immunocytochemical examination revealed that <it>sec8 </it>mutant NMJs developed more branches and presynaptic terminals during larval development, compared to controls. Synaptic electrophysiology showed no evidence that Sec8 is required for basal neurotransmission, though glutamate receptor trafficking was mildly disrupted in <it>sec8 </it>mutants. The most dramatic NMJ phenotype in <it>sec8 </it>mutants was an increase in synaptic microtubule density, which was approximately doubled compared to controls.</p> <p>Conclusion</p> <p>Sec8 is abundant in the <it>Drosophila </it>NMJ. Sec8 is required in vivo for regulation of synaptic microtubule formation, and (probably secondarily) regulation of synaptic growth and glutamate receptor trafficking. We did not find any evidence that Sec8 is required for basal neurotransmission.</p> |
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| format | Article |
| id | doaj.art-4c6caf480a9c45b5b7dd00abd630fe2f |
| institution | Directory Open Access Journal |
| issn | 1741-7007 |
| language | English |
| last_indexed | 2024-12-12T10:15:42Z |
| publishDate | 2005-12-01 |
| publisher | BMC |
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| series | BMC Biology |
| spelling | doaj.art-4c6caf480a9c45b5b7dd00abd630fe2f2022-12-22T00:27:41ZengBMCBMC Biology1741-70072005-12-01312710.1186/1741-7007-3-27Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutantsSheng QiKarr JulieChen KaiyunLiebl Faith LWFeatherstone David E<p>Abstract</p> <p>Background</p> <p>Sec8 is highly expressed in mammalian nervous systems and has been proposed to play a role in several aspects of neural development and function, including neurite outgrowth, calcium-dependent neurotransmitter secretion, trafficking of ionotropic glutamate receptors and regulation of neuronal microtubule assembly. However, these models have never been tested <it>in vivo</it>. Nervous system development and function have not been described after mutation of <it>sec8 </it>in any organism.</p> <p>Results</p> <p>We identified lethal <it>sec8 </it>mutants in an unbiased forward genetic screen for mutations causing defects in development of glutamatergic <it>Drosophila </it>neuromuscular junctions (NMJs). The <it>Drosophila </it>NMJ is genetically malleable and accessible throughout development to electrophysiology and immunocytochemistry, making it ideal for examination of the <it>sec8 </it>mutant synaptic phenotype. We developed antibodies to <it>Drosophila </it>Sec8 and showed that Sec8 is abundant at the NMJ. In our <it>sec8 </it>null mutants, in which the <it>sec8 </it>gene is specifically deleted, Sec8 immunoreactivity at the NMJ is eliminated but immunoblots reveal substantial maternal contribution in the rest of the animal. Contrary to the hypothesis that Sec8 is required for neurite outgrowth or synaptic terminal growth, immunocytochemical examination revealed that <it>sec8 </it>mutant NMJs developed more branches and presynaptic terminals during larval development, compared to controls. Synaptic electrophysiology showed no evidence that Sec8 is required for basal neurotransmission, though glutamate receptor trafficking was mildly disrupted in <it>sec8 </it>mutants. The most dramatic NMJ phenotype in <it>sec8 </it>mutants was an increase in synaptic microtubule density, which was approximately doubled compared to controls.</p> <p>Conclusion</p> <p>Sec8 is abundant in the <it>Drosophila </it>NMJ. Sec8 is required in vivo for regulation of synaptic microtubule formation, and (probably secondarily) regulation of synaptic growth and glutamate receptor trafficking. We did not find any evidence that Sec8 is required for basal neurotransmission.</p>http://www.biomedcentral.com/1741-7007/3/27 |
| spellingShingle | Sheng Qi Karr Julie Chen Kaiyun Liebl Faith LW Featherstone David E Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants BMC Biology |
| title | Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants |
| title_full | Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants |
| title_fullStr | Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants |
| title_full_unstemmed | Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants |
| title_short | Increased synaptic microtubules and altered synapse development in <it>Drosophila sec8 </it>mutants |
| title_sort | increased synaptic microtubules and altered synapse development in it drosophila sec8 it mutants |
| url | http://www.biomedcentral.com/1741-7007/3/27 |
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