Drosophila genome-wide RNAi screen identifies genes related to the miRNA pathway as regulators of the response to hypoxia

ANDRÉS DEKANTY,; CLAUDIA C. LEISHMAN,; GRACIELA L. BOCCACCIO; PABLO WAPPNER

Bariloche, Rio negro Aregmtina

Congreso; Gene Expression and RNA processing; 2007

Drosophila genome-wide RNAi screen identifies genes related to the miRNA pathway as regulators of the response to hypoxia Andrés Dekanty, Claudia C. Leishman, Graciela L. Boccaccio and Pablo Wappner Fundación Instituto Leloir, Buenos Aires, Argentina. e-mail: adekanty@leloir.org.ar Cellular response to low oxygen tension (hypoxia) involves changes in gene expression that promote adaptation to the hypoxic stress. This transcriptional response to hypoxia is a highly conserved mechanism mediated by the Hypoxia Inducible Factor, HIF. We have previously defined a hypoxia-responsive system homologous to HIF in Drosophila, where the proteins Sima and Tango are the homologues of HIF-a and b subunits, respectively. To identify novel genes involved in the regulation of the transcriptional response to hypoxia, a reporter, in which a HIF-Responsive-Element (HRE) drives the expression of firefly luciferase, was used in a genome-wide RNA interference screen in Drosophila S2 cells. The screen led to the identification of about 200 genes presumably required for the hypoxic response, among which we identified components of the miRNA pathway. We have demonstrated both in cell culture and in living embryos, that Argonaute1 (AGO1) is absolutely required for hypoxia-dependent transcription (el “read out” del reportero de luciferasa incluye too traducción. O sabe qeu el efcot de Ago es a nivel trasncripcional?). This requirement also applies for other members of the miRNA machinery, strongly suggesting that the miRNA pathway is involved in the hypoxic response. We analyzed the dynamics of Processing Bodies (PB), silencing foci  where miRNA-silenced transcripts accumulates , in response to hypoxia and observed a dramatic increase in the number and size of PB. Interestingly, PB enhancement was dramatically abrogated upon depletion of AGO1 or GW182. We propose that the miRNA machinery plays a physiological role in the cellular response to hypoxia.