MicroRNA Transgene Overexpression Complements Deficiency-Based Modifier Screens in Drosophila

Abstract

Dosage-sensitive modifier screening is a powerful tool for linking genes to biological processes. Use of chromosomal deletions permits sampling the effects of removing groups of genes related by position on the chromosome. Here, we explore the use of inducible microRNA transgenes as a complement to deficiency-based modifier screens. miRNAs are predicted to have hundreds of targets. miRNA overexpression provides an efficient means to reduces expression of large gene sets. A collection of transgenes was prepared to allow overexpression of 89 miRNAs or miRNA clusters. These transgenes and a set of genomic deficiencies were screened for their ability to modify the bristle phenotype of the cell-cycle regulator minus. Sixteen miRNAs were identified as dominant suppressors, while the deficiency screen uncovered four genomic regions that contain a dominant suppressor. Comparing the genes uncovered by the deletions with predicted miRNA targets uncovered a small set of candidate suppressors. Two candidates were identified as suppressors of the minus phenotype, Cullin-4 and CG5199/Cut8. Additionally, we show that Cullin-4 acts through its substrate receptor Cdt2 to suppress the minus phenotype. We suggest that inducible microRNA transgenes are a useful complement to deficiency-based modifier screens.

Regulation of Drosophila circadian rhythms by miRNA let-7 is mediated by a regulatory cycle

“…Thus, it may be necessary to perform a genetic screen of individual miRNAs in fly head circadian cells to investigate their potential role in circadian regulation. Recently, a transgenic UAS-miRNA library in Drosophila has been constructed [54][55][56] . This library circumvents the redundancy issues inherent in loss-of-function screens by facilitating the controlled misexpression of individual miRNAs and is a useful tool to complement loss-of-function approaches.…”

A genome-wide transgenic resource for conditional expression ofDrosophilamicroRNAs

“…Beyond a limited set of bristle modifiers, however, their analysis primarily revealed lethality as the outcome of miRNA expression (Szuplewski et al, 2012). We find over 100 of our miRNA transgenes induced lethality when broadly expressed with da-Gal4.…”

“…While this work was under review, Cohen and colleagues described a smaller set of UAS-miRNA transgenes and their application towards searching for modifiers of a bristle phenotype of the cell cycle regulator minus (Szuplewski et al, 2012). Beyond a limited set of bristle modifiers, however, their analysis primarily revealed lethality as the outcome of miRNA expression (Szuplewski et al, 2012).…”

Functional Characterization of Drosophila microRNAs by a Novel in Vivo Library

“…While this work was under review, Lai and colleagues described their efforts to generate a similar UAS-miRNA resource (Bejarano et al 2012). Furthermore, an earlier publication reported a smaller collection of UAS-miRNA lines that was used as a tool to complement genetic deficiency screening (Szuplewski et al 2012). Our transgenic strategy provides an additional tool that greatly extends the number of experimentally approachable miRNAs.…”