Multiple RNA regulatory elements mediate distinct steps in localization of oskar mRNA

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 169-178 ◽  
Author(s):  
J. Kim-Ha ◽  
P.J. Webster ◽  
J.L. Smith ◽  
P.M. Macdonald
Keyword(s):  
Pattern Formation ◽  
Untranslated Region ◽  
Anterior Margin ◽  
Regulatory Elements ◽  
Mrna Localization ◽  
Posterior Pole ◽  
Nurse Cells ◽  
Cis Acting ◽  
Cytoplasmic Proteins ◽  
Body Patterning

Pattern formation in the early development of many organisms relies on localized cytoplasmic proteins, which can be prelocalized as mRNAs. The Drosophila oskar gene, required both for posterior body patterning and germ cell determination, encodes one such mRNA. Localization of oskar mRNA is an elaborate process involving movement of the transcript first into the oocyte from adjacent interconnected nurse cells and then across the length of the oocyte to its posterior pole. We have mapped RNA regulatory elements that direct this localization. Using a hybrid lacZ/oskar mRNA, we identify several elements within the oskar 3′ untranslated region that affect different steps in the process: the early movement into the oocyte, accumulation at the anterior margin of the oocyte and finally localization to the posterior pole. This use of multiple cis-acting elements suggests that localization may be orchestrated in a combinatorial fashion, thereby allowing localized mRNAs with ultimately different destinations to employ common mechanisms for shared intermediate steps.

cis-acting elements involved in the alternative translation initiation process of human basic fibroblast growth factor mRNA

1992 ◽  
Vol 12 (10) ◽  
pp. 4796-4805
Author(s):  
A C Prats ◽  
S Vagner ◽  
H Prats ◽  
F Amalric
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Untranslated Region ◽  
Specific Effect ◽  
Regulatory Elements ◽  
Fibroblast Growth ◽  
Cis Acting ◽  
Initiation Of Translation ◽  
Alternative Translation

Four forms of basic fibroblast growth factor (bFGF) are synthesized from the same mRNA, resulting from alternative initiations of translation at three CUG start codons and one AUG start codon. The CUG- and AUG-initiated forms have distinct intracellular localizations and can modify cell phenotypes differently, indicating that control of the alternative expression of the different forms of bFGF has an important impact on the cell. In this study, we investigated the roles of the mRNA 5' untranslated region and the alternatively translated region located between the CUG and AUG codons in the regulation of alternative translation of the different forms of bFGF. Deletions and site-directed mutagenesis were carried out in bFGF mRNA leader, and translation was studied in vitro and in vivo. The results enabled us to identify five cis-acting RNA elements (two in the 5' untranslated region and three in the alternatively translated region) involved in the regulation of either global or alternative initiation of translation. Each of these elements had a specific effect on the level of synthesis of the different forms of bFGF. Furthermore, we showed that the 5' untranslated region regulatory elements had different effects on bFGF translation, depending on the translation system used. These results suggest that bFGF translation is modulated by cis-acting elements corresponding to secondary or tertiary RNA structures, which could be the targets of cell-specific trans-acting factors.

Role for mRNA localization in translational activation but not spatial restriction of nanos RNA

Development ◽  
1999 ◽  
Vol 126 (4) ◽  
pp. 659-669 ◽  
Author(s):  
S.E. Bergsten ◽  
E.R. Gavis
Keyword(s):  
Translational Control ◽  
Rna Localization ◽  
Early Embryo ◽  
Posterior Pole ◽  
Translational Repression ◽  
Control Element ◽  
Regulatory Sequences ◽  
Cis Acting ◽  
Body Patterning ◽  
Localization Signal

Patterning of the anterior-posterior body axis during Drosophila development depends on the restriction of Nanos protein to the posterior of the early embryo. Synthesis of Nanos occurs only when maternally provided nanos RNA is localized to the posterior pole by a large, cis-acting signal in the nanos 3′ untranslated region (3′UTR); translation of unlocalized nanos RNA is repressed by a 90 nucleotide Translational Control Element (TCE), also in the 3′UTR. We now show quantitatively that the majority of nanos RNA in the embryo is not localized to the posterior pole but is distributed throughout the cytoplasm, indicating that translational repression is the primary mechanism for restricting production of Nanos protein to the posterior. Through an analysis of transgenes bearing multiple copies of nanos 3′UTR regulatory sequences, we provide evidence that localization of nanos RNA by components of the posteriorly localized germ plasm activates its translation by preventing interaction of nanos RNA with translational repressors. This mutually exclusive relationship between translational repression and RNA localization is mediated by a 180 nucleotide region of the nanos localization signal, containing the TCE. These studies suggest that the ability of RNA localization to direct wild-type body patterning also requires recognition of multiple, unique elements within the nanos localization signal by novel factors. Finally, we propose that differences in the efficiencies with which different RNAs are localized result from the use of temporally distinct localization pathways during oogenesis.

scholarly journals 3′ non-translated sequences in Drosophila cyclin B transcripts direct posterior pole accumulation late in oogenesis and peri-nuclear association in syncytial embryos

Development ◽  
1992 ◽  
Vol 115 (4) ◽  
pp. 989-997 ◽  
Author(s):  
B. Dalby ◽  
D.M. Glover
Keyword(s):  
Untranslated Region ◽  
Cyclin A ◽  
Posterior Pole ◽  
The Body ◽  
Cyclin B ◽  
Nurse Cells ◽  
Nuclear Localisation ◽  
Oocyte Cytoplasm ◽  
Nuclear Association ◽  
Cyclin Genes

We have characterised forms of the Drosophila cyclin B transcript that differ as a result of a splicing event which removes a nucleotide segment from the 3′ untranslated region. In oogenesis, both cyclin A RNA and a shorter form of the cyclin B transcript are seen in the cells of the germarium that are undergoing mitosis. The shorter cyclin B transcript alone is then detectable in the presumptive oocyte until stages 7–8 of oogenesis. Both cyclin A RNA and a longer form of the cyclin B RNA are then synthesised in the nurse cells during stages 9–11, to be deposited in the oocyte during stages 11–12. These transcripts become evenly distributed throughout the oocyte cytoplasm but, in addition, those of cyclin B become concentrated at the posterior pole. Examination of the distributions of RNAs transcribed from chimeric cyclin genes indicates that sequences in the 3′ untranslated region of the larger cyclin B RNA are required both for it to become concentrated at the posterior pole and to direct those transcripts in the body of the syncytial embryo to their peri-nuclear localisation. These sequences are disrupted by the splicing event which generates smaller cyclin B transcripts.

RNA regulatory element BLE1 directs the early steps of bicoid mRNA localization

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1233-1243 ◽  
Author(s):  
P.M. Macdonald ◽  
K. Kerr ◽  
J.L. Smith ◽  
A. Leask
Keyword(s):  
Untranslated Region ◽  
Regulatory Element ◽  
Essential Element ◽  
Mrna Localization ◽  
Morphogen Gradient ◽  
Anterior Pole ◽  
Functional Elements ◽  
Cis Acting ◽  
Localization Signal ◽  
Drosophila Embryos

Deployment of the bicoid morphogen gradient in early Drosophila embryos requires the prelocalization of bicoid mRNA to the anterior pole of the egg. This anterior localization is mediated by a cis-acting localization signal contained within the 3′ untranslated region of the bicoid mRNA. Here we use a series of bicoid transgenes carrying small deletions in the 3′ untranslated region to survey for functional elements that constitute the localization signal. We identify and characterize one essential element, BLE1, which specifically directs the early steps of localization. In addition, we find that many deletions within the bicoid mRNA 3′ untranslated region impair but do not prevent localization. One such deletion specifically interferes with a later step in localization. Thus the bicoid mRNA localization signal appears to consist of multiple different elements, each responsible for different steps in the localization process.

Multiple cis-acting targeting sequences are required for orb mRNA localization during Drosophila oogenesis

1994 ◽  
Vol 14 (4) ◽  
pp. 2235-2242
Author(s):  
V Lantz ◽  
P Schedl
Keyword(s):  
Untranslated Region ◽  
Germ Line ◽  
Critical Role ◽  
Positional Information ◽  
Mrna Localization ◽  
Early Embryo ◽  
Developmental Systems ◽  
Localization Pattern ◽  
Cis Acting ◽  
Anterior Posterior

The targeting of positional information to specific regions of the oocyte or early embryo is one of the key processes in establishing anterior-posterior and dorsal-ventral polarity. In many developmental systems, this is accomplished by localization of mRNAs. The germ line-specific Drosophila orb gene plays a critical role in defining both axes of the developing oocyte, and its mRNA is localized in a complex pattern during oogenesis. We have identified a 280-bp sequence from the orb 3' untranslated region capable of reproducing this complex localization pattern. Furthermore, we have found that multiple cis-acting elements appear to be required for proper targeting of orb mRNA.

Drosophila virilis oskar transgenes direct body patterning but not pole cell formation or maintenance of mRNA localization in D. melanogaster

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 2027-2037 ◽  
Author(s):  
P.J. Webster ◽  
J. Suen ◽  
P.M. Macdonald
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cell ◽  
Cell Formation ◽  
Mrna Localization ◽  
Early Embryo ◽  
Posterior Pole ◽  
Early Embryogenesis ◽  
Drosophila Virilis ◽  
Pole Cell ◽  
Body Patterning

The Drosophila melanogaster gene oskar is required for both posterior body patterning and germline formation in the early embryo; precisely how oskar functions is unknown. The oskar transcript is localized to the posterior pole of the developing oocyte, and oskar mRNA and protein are maintained at the pole through early embryogenesis. The posterior maintenance of oskar mRNA is dependent upon the presence of oskar protein. We have cloned and characterized the Drosophila virilis oskar homologue, virosk, and examined its activity as a transgene in Drosophila melanogaster flies. We find that the cis-acting mRNA localization signals are conserved, although the virosk transcript also transiently accumulates at novel intermediate sites. The virosk protein, however, shows substantial differences from oskar: while virosk is able to rescue body patterning in a D. melanogaster oskar- background, it is impaired in both mRNA maintenance and pole cell formation. Furthermore, virosk induces a dominant maternal-effect lethality when introduced into a wild-type background, and interferes with the posterior maintenance of the endogenous oskar transcript in early embryogenesis. Our data suggest that virosk protein is unable to anchor at the posterior pole of the early embryo; this defect could account for all of the characteristics of virosk mentioned above. Our observations support a model in which oskar protein functions both by nucleating the factors necessary for the activation of the posterior body patterning determinant and the germ cell determinant, and by anchoring these factors to the posterior pole of the embryo. While the posterior body patterning determinant need not be correctly localized to provide body patterning activity, the germ cell determinant may need to be highly concentrated adjacent to the cortex in order to direct pole cell formation.

scholarly journals Isolation of a Ribonucleoprotein Complex Involved in mRNA Localization in Drosophila Oocytes

2000 ◽  
Vol 148 (3) ◽  
pp. 427-440 ◽  
Author(s):  
James E. Wilhelm ◽  
Jennifer Mansfield ◽  
Nora Hom-Booher ◽  
Shengxian Wang ◽  
Christoph W. Turck ◽  
...  
Keyword(s):  
Rna Binding ◽  
Mrna Localization ◽  
Posterior Pole ◽  
Nurse Cells ◽  
Embryonic Patterning ◽  
Large Protein ◽  
Genetic Studies ◽  
Large Protein Complex ◽  
Cold Shock Domain

Localization of bicoid (bcd) mRNA to the anterior and oskar (osk) mRNA to the posterior of the Drosophila oocyte is critical for embryonic patterning. Previous genetic studies implicated exuperantia (exu) in bcd mRNA localization, but its role in this process is not understood. We have biochemically isolated Exu and show that it is part of a large RNase-sensitive complex that contains at least seven other proteins. One of these proteins was identified as the cold shock domain RNA-binding protein Ypsilon Schachtel (Yps), which we show binds directly to Exu and colocalizes with Exu in both the oocyte and nurse cells of the Drosophila egg chamber. Surprisingly, the Exu–Yps complex contains osk mRNA. This biochemical result led us to reexamine the role of Exu in the localization of osk mRNA. We discovered that exu-null mutants are defective in osk mRNA localization in both nurse cells and the oocyte. Furthermore, both Exu/Yps particles and osk mRNA follow a similar temporal pattern of localization in which they transiently accumulate at the oocyte anterior and subsequently localize to the posterior pole. We propose that Exu is a core component of a large protein complex involved in localizing mRNAs both within nurse cells and the developing oocyte.

scholarly journals Multiple cis-acting targeting sequences are required for orb mRNA localization during Drosophila oogenesis.

1994 ◽  
Vol 14 (4) ◽  
pp. 2235-2242 ◽  
Author(s):  
V Lantz ◽  
P Schedl
Keyword(s):  
Untranslated Region ◽  
Germ Line ◽  
Critical Role ◽  
Positional Information ◽  
Mrna Localization ◽  
Early Embryo ◽  
Developmental Systems ◽  
Localization Pattern ◽  
Cis Acting ◽  
Anterior Posterior

The targeting of positional information to specific regions of the oocyte or early embryo is one of the key processes in establishing anterior-posterior and dorsal-ventral polarity. In many developmental systems, this is accomplished by localization of mRNAs. The germ line-specific Drosophila orb gene plays a critical role in defining both axes of the developing oocyte, and its mRNA is localized in a complex pattern during oogenesis. We have identified a 280-bp sequence from the orb 3' untranslated region capable of reproducing this complex localization pattern. Furthermore, we have found that multiple cis-acting elements appear to be required for proper targeting of orb mRNA.

scholarly journals cis-acting elements involved in the alternative translation initiation process of human basic fibroblast growth factor mRNA.

1992 ◽  
Vol 12 (10) ◽  
pp. 4796-4805 ◽  
Author(s):  
A C Prats ◽  
S Vagner ◽  
H Prats ◽  
F Amalric
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Untranslated Region ◽  
Specific Effect ◽  
Regulatory Elements ◽  
Fibroblast Growth ◽  
Cis Acting ◽  
Initiation Of Translation ◽  
Alternative Translation

Four forms of basic fibroblast growth factor (bFGF) are synthesized from the same mRNA, resulting from alternative initiations of translation at three CUG start codons and one AUG start codon. The CUG- and AUG-initiated forms have distinct intracellular localizations and can modify cell phenotypes differently, indicating that control of the alternative expression of the different forms of bFGF has an important impact on the cell. In this study, we investigated the roles of the mRNA 5' untranslated region and the alternatively translated region located between the CUG and AUG codons in the regulation of alternative translation of the different forms of bFGF. Deletions and site-directed mutagenesis were carried out in bFGF mRNA leader, and translation was studied in vitro and in vivo. The results enabled us to identify five cis-acting RNA elements (two in the 5' untranslated region and three in the alternatively translated region) involved in the regulation of either global or alternative initiation of translation. Each of these elements had a specific effect on the level of synthesis of the different forms of bFGF. Furthermore, we showed that the 5' untranslated region regulatory elements had different effects on bFGF translation, depending on the translation system used. These results suggest that bFGF translation is modulated by cis-acting elements corresponding to secondary or tertiary RNA structures, which could be the targets of cell-specific trans-acting factors.

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