Smaug, a Novel RNA-Binding Protein that Operates a Translational Switch in Drosophila

Dahanukar, Anupama; Walker, James A.; Wharton, Robin P.

doi:10.1016/s1097-2765(00)80368-8

Cited by 205 publications

(252 citation statements)

References 46 publications

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“…2a). Regulatory elements of these genes are known to cause germ cell-specific expression, either by specifically directing zygotic transcription in these cells (vasa) (16) or by spatially regulating translation and stability of maternal mRNA, which leads to expression at the posterior of the embryo where germ cells form (nanos) (17)(18)(19)(20)(21)(22)(23).…”

Section: Resultsmentioning

confidence: 99%

An optimized transgenesis system for Drosophila using germ-line-specific φC31 integrases

Bischof

Maeda²,

Hediger³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

1,793

2,089

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Germ-line transformation via transposable elements is a powerful tool to study gene function in Drosophila melanogaster. However, some inherent characteristics of transposon-mediated transgenesis limit its use for transgene analysis. Here, we circumvent these limitations by optimizing a C31-based integration system. We generated a collection of lines with precisely mapped attP sites that allow the insertion of transgenes into many different predetermined intergenic locations throughout the fly genome. By using regulatory elements of the nanos and vasa genes, we established endogenous sources of the C31 integrase, eliminating the difficulties of coinjecting integrase mRNA and raising the transformation efficiency. Moreover, to discriminate between specific and rare nonspecific integration events, a white gene-based reconstitution system was generated that enables visual selection for precise attP targeting. Finally, we demonstrate that our chromosomal attP sites can be modified in situ, extending their scope while retaining their properties as landing sites. The efficiency, ease-of-use, and versatility obtained here with the C31-based integration system represents an important advance in transgenesis and opens up the possibility of systematic, highthroughput screening of large cDNA sets and regulatory elements.attP landing sites ͉ germ-line transformation ͉ site-specific integration A major goal in the present era of genomics is to identify and functionally characterize all genes relevant to a specific pathway or biological process. With its powerful repertoire of genetic tools, the multicellular model organism Drosophila melanogaster has played an eminent role in this endeavor (1). One method to identify relevant genes is to perform chemical mutagenesis screens of various kinds. Another very fruitful approach in Drosophila has been the use of P-element-mediated germ-line transformation (2, 3), especially when combined with tools such as the Gal4/UAS expression system (4) or when it is used for insertional mutagenesis (5, 6). One characteristic of P-elements is their random integration behavior. Although this ''randomness'' is advantageous for generating mutations and deletions, it is generally not ideal for transgene analysis. The random integration of P-elements necessitates considerable effort to map insertions. Genomic position effects complicate the analysis of transgenes and render precise structure/ function analyses nearly impossible. A further shortcoming of the P-element system is its relatively moderate transformation efficiency, a significant hurdle to any large-scale transgenesis effort.Strategies have been developed to circumvent the problem of randomness by targeted integration systems in Drosophila, which are generally based on the FLP and Cre recombinases (7-9, 32). Such techniques permit precise targeting to genomic landing sites but are still handicapped by transformation rates that are, at best, moderately higher than those achieved with the P-element system (8). Furthermore, especially for FL...

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Section: Resultsmentioning

confidence: 99%

An optimized transgenesis system for Drosophila using germ-line-specific φC31 integrases

Bischof

Maeda²,

Hediger³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

1,793

2,089

View full text Add to dashboard Cite

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“…Six of these proteins are involved in patterning the early embryo and directing morphogenesis (including Bicoid, Torso, Toll, Nanos, Hunchback, and Caudal; Driever and Nusslein-Volhard, 1988;Casanova and Struhl, 1989;Tautz and Pfeifle, 1989;Gay and Keith, 1992;Wang et al, 1994;Dubnau and Struhl, 1996). The remaining two proteins known to be translated upon egg activation in Drosophila are Smaug (Smg), which plays a major role in the degradation of maternal transcripts (see below; Dahanukar et al, 1999;Tadros et al, 2007) and the Cdc25 homolog String, which activates MPF and is thus important for the rapid nuclear divisions that occur during early embryogenesis (Spradling, 1993). In Xenopus, maternally encoded proteins are similarly necessary for establishment of the embryonic axis and rapid early cell divisions (reviewed in .…”

Section: Maternal Transcript Translationmentioning

confidence: 99%

Transitioning from egg to embryo: Triggers and mechanisms of egg activation

Horner

Wolfner

2008

Developmental Dynamics

181

177

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The transition from mature oocyte to developing embryo requires a coordinated series of events, collectively known as egg activation. Egg activation includes changes to egg coverings to prevent polyspermy, release of oocyte meiotic arrest, generation of haploid female and male pronuclei, changes in maternal mRNAs and protein populations, and cytoskeletal rearrangements. In many animals, egg activation is triggered by fertilization, which increases intracellular calcium within the oocyte and thereby regulates molecular events of egg activation. In other animals, fertilization-independent external signals, including mechanical stimulation of eggs and/or changes in ionic milieu, trigger activation. Recent studies have clarified the upstream portion of pathways leading to eggshell changes and cell cycle resumption and have identified activation-induced changes in maternal mRNA and protein profiles that can identify molecular players in the downstream events of egg activation. We review signals that trigger activation and how they link to subsequent molecular events of egg activation. Developmental Dynamics 237:527-544, 2008.

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“…Smaug (SMG) is the major regulator of this mRNA-destabilizing activity. SMG protein is not present in mature oocytes but is present in embryos (Smibert et al 1996;Dahanukar et al 1999). smg mRNA has been reported to be polyadenylated upon egg activation, correlating with, but not absolutely required for, its translation (Tadros et al 2007).…”

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confidence: 99%

Wispy, the Drosophila Homolog of GLD-2, Is Required During Oogenesis and Egg Activation

et al. 2008

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Egg activation is the process that modifies mature, arrested oocytes so that embryo development can proceed. One key aspect of egg activation is the cytoplasmic polyadenylation of certain maternal mRNAs to permit or enhance their translation. wispy (wisp) maternal-effect mutations in Drosophila block development during the egg-to-embryo transition. We show here that the wisp gene encodes a member of the GLD-2 family of cytoplasmic poly(A) polymerases (PAPs). The WISP protein is required for poly(A) tail elongation of bicoid, Toll, and torso mRNAs upon egg activation. In Drosophila, WISP and Smaug (SMG) have previously been reported to be required to trigger the destabilization of maternal mRNAs during egg activation. SMG is the major regulator of this activity. We report here that SMG is still translated in activated eggs from wisp mutant mothers, indicating that WISP does not regulate mRNA stability by controlling the translation of smg mRNA. We have also analyzed in detail the very early developmental arrest associated with wisp mutations. Pronuclear migration does not occur in activated eggs laid by wisp mutant females. Finally, we find that WISP function is also needed during oogenesis to regulate the poly(A) tail length of dmos during oocyte maturation and to maintain a high level of active (phospho-) mitogen-activated protein kinases (MAPKs).

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Smaug, a Novel RNA-Binding Protein that Operates a Translational Switch in Drosophila

Cited by 205 publications

References 46 publications

An optimized transgenesis system for Drosophila using germ-line-specific φC31 integrases

An optimized transgenesis system for Drosophila using germ-line-specific φC31 integrases

Transitioning from egg to embryo: Triggers and mechanisms of egg activation

Wispy, the Drosophila Homolog of GLD-2, Is Required During Oogenesis and Egg Activation

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