| 1. |
- Talamillo, Ana, et al.
(författare)
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Sm3 is required for Drosophila melanogaster metamorphosis.
- 2008
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Ingår i: Development. ; 135:9, s. 1659-1668
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Tidskriftsartikel (refereegranskat)abstract
- Sumoylation, the covalent attachment of the small ubiquitin-related modifier SUMO to target proteins, regulates different cellular processes, although its role in the control of development remains unclear. We studied the role of sumoylation during Drosophila development by using RNAi to reduce smt3 mRNA levels in specific tissues. smt3 knockdown in the prothoracic gland, which controls key developmental processes through the synthesis and release of ecdysteroids, caused a 4-fold prolongation of larval life and completely blocked the transition from larval to pupal stages. The reduced ecdysteroid titer of smt3 knockdown compared with wild-type larvae explains this phenotype. In fact, after dietary administration of exogenous 20-hydroxyecdysone, knockdown larvae formed pupal cases. The phenotype is not due to massive cell death or degeneration of the prothoracic glands at the time when puparium formation should occur. Knockdown cells show alterations in expression levels and/or the subcellular localisation of enzymes and transcription factors involved in the regulation of ecdysteroid synthesis. In addition, they present reduced intracellular channels and a reduced content of lipid droplets and cholesterol, which could explain the deficit in steroidogenesis. In summary, our study indicates that Smt3 is required for the ecdysteroid synthesis pathway at the time of puparium formation.
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| 2. |
- Talamillo, Ana, et al.
(författare)
-
Sumoylation is necessary for the metamorphosis of Drosophila melanogaster
- 2007
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Ingår i: European Drosophila Research Conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To study in vivo the role of the ubiquitin-like protein Smt3 (Sumo) during Drosophila development, we generated transgenic flies carrying the transgene UAS-smt3i to reduce smt3 mRNA levels in specific groups of cells. Low smt3 in the prothoracic gland, the tissue responsible for the synthesis of ecdysteroids, prevents metamorphosis. RNAi knockdown larvae stop their development in their last larval stage and remain alive for up to a month, during which they continue to eat and gain weight. Their prothoracic glands have fewer, but larger cells than normal, similar to larvae mutant in lesswright, the homologue of the Sumo conjugating enzyme gene Ubc9. They also have lower ecdysteroid titre than WT. After dietary administration of exogenous ecdysone some of these larvae form pupal cases, but do not proceed further in development and die. However, addition of cholesterol or 7-dehydrocholesterol does not rescue the larval phenotype, indicating that sumoylation must be necessary for later steps in the ecdysteroid synthesis pathway. Interestingly, we observed that, in larvae with lower levels of smt3, as well as in lesswright mutants, the subcellular localization and expression levels of factors involved in the regulation of ecdysteroids synthesis, are altered, including Molting defective, Without children, _-Ftz transcription factor 1 and Disembodied. We also investigate the sumoylation capacity of these and other factors involved in ecdysteroid synthesis.
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