The expression of the let-7 small regulatory RNA is controlled by ecdysone during metamorphosis in Drosophila melanogaster.
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.
Sempere
Lorenzo F
LF
Department of Genetics, Dartmouth College, Hanover, New Hampshire 03755, USA.
Dubrovsky
Edward B
EB
Dubrovskaya
Veronica A
VA
Berger
Edward M
EM
Ambros
Victor
V
D000818:Animals; D017931:DNA Primers; D004331:Drosophila melanogaster / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D004440:Ecdysone / Q000494:pharmacology*; D004441:Ecdysterone / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D007814:Larva; D008675:Metamorphosis, Biological / Q000187:drug effects / Q000235:genetics*; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics; D011679:Pupa; D018510:RNA, Helminth / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000187:drug effects
D017931:DNA Primers; D020319:Oligodeoxyribonucleotides, Antisense; D018510:RNA, Helminth; D012342:RNA, Small Nuclear; D004440:Ecdysone; D004441:Ecdysterone