| Citation |
Sempere, L.F., Dubrovsky, E.B., Dubrovskaya, V.A., Berger, E.M., Ambros, V. (2002). The expression of the let-7 small regulatory RNA is controlled by ecdysone during metamorphosis in Drosophila melanogaster. Dev. Biol. 244(1): 170--179. |
| PubMed Abstract |
In Caenorhabditis elegans, the heterochronic pathway controls the timing of developmental events during the larval stages.
A component of this pathway, the let-7 small regulatory RNA, is expressed at the late stages of development and promotes the
transition from larval to adult (L/A) stages. The stage-specificity of let-7 expression, which is crucial for the proper timing
of the worm L/A transition, is conserved in Drosophila melanogaster and other invertebrates. In Drosophila, pulses of the
steroid hormone 20-hydroxyecdysone (ecdysone) control the timing of the transition from larval to pupal to adult stages. To
test whether let-7 expression is regulated by ecdysone in Drosophila, we used Northern blot analysis to examine the effect
of altered ecdysone levels on let-7 expression in mutant animals, organ cultures, and S2 cultured cells. Experiments were
conducted to test the role of Broad-Complex (BR-C), an essential component in the ecdysone pathway, in let-7 expression. We
show that ecdysone and BR-C are required for let-7 expression, indicating that the ecdysone pathway regulates the temporal
expression of let-7 in Drosophila. These results demonstrate an interaction between steroid hormone signaling and the heterochronic
pathway in insects.
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