Efficient Protein Trafficking Requires Trailer Hitch, a Component of a Ribonucleoprotein Complex Localized to the ER in Drosophila

Wilhelm, James E.; Buszczak, Michael; Sayles, Suzanne

doi:10.1016/j.devcel.2005.09.015

Cited by 152 publications

(233 citation statements)

References 57 publications

(56 reference statements)

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“…Usually, where tested, interactions between Yps/Cey proteins and other complex proteins have been noted to require RNA (19,20,44,68,69), similarly to FRGY2 in Xenopus oocytes (60) (this study). RNA is not required between Dhh1 and Pat1 (70), nor between Tral and Me31B, Yps, and Cup (69), also in line with Xenopus oocyte studies (60) (this study).…”

Section: Discussionmentioning

confidence: 86%

“…Co-immunoprecipitation and pull-down assays have revealed interactions between paralogs of p54 and RAP55 proteins in C. elegans embryos (Cgh-1 and CAR-1) (44,68) and Drosophila oocytes (Me31B and Tral) (69). The Xp54-P100/ Pat1 interaction is conserved in yeast (Dhh1 and Pat1) (70) and Drosophila Schneider cells (Me31B and Hpat) (71).…”

Section: Discussionmentioning

confidence: 99%

“…3 In yeast, Dhh1 and Pat1 have both been characterized as translational repressors and decapping enhancers (32,70). Homologs of FRGY2, considered to be nonspecific cap-dependent translational repressors (72), interact with p54/RAP55 proteins in flies (Yps) (19,20,69) and worms (Cey) (44,68), and Drosophila Orb (CPEB) co-immunoprecipitates with Yps (73). Usually, where tested, interactions between Yps/Cey proteins and other complex proteins have been noted to require RNA (19,20,44,68,69), similarly to FRGY2 in Xenopus oocytes (60) (this study).…”

Section: Discussionmentioning

confidence: 99%

“…Homologs of FRGY2, considered to be nonspecific cap-dependent translational repressors (72), interact with p54/RAP55 proteins in flies (Yps) (19,20,69) and worms (Cey) (44,68), and Drosophila Orb (CPEB) co-immunoprecipitates with Yps (73). Usually, where tested, interactions between Yps/Cey proteins and other complex proteins have been noted to require RNA (19,20,44,68,69), similarly to FRGY2 in Xenopus oocytes (60) (this study). RNA is not required between Dhh1 and Pat1 (70), nor between Tral and Me31B, Yps, and Cup (69), also in line with Xenopus oocyte studies (60) (this study).…”

Section: Discussionmentioning

confidence: 99%

“…For example, Xp54 (Dhh1, Me31B, Cgh-1, and RCK) and RAP55 (Scd6, Tral, and CAR-1) proteins localize to P bodies in yeast and mammalian cells (37,40,74), in Drosophila S2 cells (71), and neuronal granules (45), in germinal granules in Drosophila oocytes (69,75), and in P granules in C. elegans embryos (44,68,76). In Drosophila, Orb, Me31B, Tral, and Cup localize within the future oocyte in developing regions 2 and 3 of the germarium, composed of germ line cysts, and are associated with the Balbiani body (69,75,77). The Balbiani body is a collection of organelles, including mitochondria, endoplasmic reticulum, and granulofibrillar material, located adjacent to the nucleus in young oocytes of diverse species.…”

Section: Discussionmentioning

confidence: 99%

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CPEB Interacts with an Ovary-specific eIF4E and 4E-T in Early Xenopus Oocytes

Minshall

Reiter

Weil

et al. 2007

Journal of Biological Chemistry

169

240

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CPEB (cytoplasmic polyadenylation element-binding protein) is an important regulator of translation in oocytes and neurons. Although previous studies of CPEB in late Xenopus oocytes involve the eIF4E-binding protein maskin as the key factor for the repression of maternal mRNA, a second mechanism must exist, since maskin is absent earlier in oogenesis. Using co-immunoprecipitation and gel filtration assays, we show that CPEB specifically interacts, via protein/protein interactions, with the RNA helicase Xp54, the RNA-binding proteins P100(Pat1) and RAP55, the eIF4E-binding protein 4E-T, and an eIF4E protein. Remarkably, these CPEB complex proteins have been characterized, in one or more organism, as P-body, maternal, or neuronal granule components. We do not detect interactions with eIF4E1a, the canonical cap-binding factor, eIF4G, or eIF4A or with proteins expressed late in oogenesis, including maskin, PARN, and 4E-BP1. The eIF4E protein was identified as eIF4E1b, a close homolog of eIF4E1a, whose expression is restricted to oocytes and early embryos. Although eIF4E1b possesses all residues required for cap and eIF4G binding, it binds m 7 GTP weakly, and in pull-down assays, rather than binding eIF4G, it binds 4E-T, in a manner independent of the consensus eIF4E-binding site, YSKEELL. Wild type and Y-A mutant 4E-T (which binds eIF4E1b but not eIF4E1a), when tethered to a reporter mRNA, represses its translation in a cap-dependent manner, and injection of eIF4E1b antibody accelerates meiotic maturation. Altogether, our data suggest that CPEB, partnered with several highly conserved RNA-binding partners, inhibits protein synthesis in oocytes using a novel pairing of 4E-T and eIF4E1b.Selective protein synthesis in oocytes, eggs, and early embryos of many organisms drives several critical aspects of early development, including meiotic maturation and entry into mitosis, establishment of embryonic axes, and cell fate determination. Protein synthesis is usually regulated at the initiation stage, mediated by the 5Ј m 7 GpppN mRNA cap structure bound by the translation initiation complex eIF4F, composed of eIF4E, the cap-binding protein, the RNA helicase eIF4A, and the large scaffold protein eIF4G, which has a consensus binding site YXXXXL for eIF4E, and additional sites for eIF3 and the poly(A)-binding protein. eIF3 recruits the small ribosomal subunit, whereas the eIF4E-eIF4G-poly(A)-binding protein relay results in the so-called "closed loop" model, responsible for the synergistic enhancement of translation by capped and polyadenylated mRNAs. A hallmark of translational control mechanisms is the role of mRNA-binding proteins, which recognize specific (and usually) 3Ј-UTR 2 cis-elements and influence the recruitment of the small ribosomal subunit to the 5Ј cap (reviewed in Refs. 1-3). Probably, the best studied mRNA-binding protein is CPEB1 (cytoplasmic polyadenylation-binding protein 1), characterized in flies, worms, clams, Aplysia, Xenopus, and mammals, which in its conserved C terminus contains two tandem RNA reco...

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Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

CPEB Interacts with an Ovary-specific eIF4E and 4E-T in Early Xenopus Oocytes

Minshall

Reiter

Weil

et al. 2007

Journal of Biological Chemistry

169

240

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Drosophila ataxin‐2 gene encodes two differentially expressed isoforms and its function in larval fat body is crucial for development of peripheral tissues

et al. 2016

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Different isoforms of ataxin‐2 are predicted in Drosophila and may underlie different cellular processes. Here, we validated the isoforms B and C of Drosophila ataxin‐2 locus (dAtx2), which we found to be expressed in various tissues and at different levels during development. dAtx2‐B mRNA was detected at low amounts during all developmental stages, whereas dAtx2‐C mRNA levels increase by eightfold from L3 to pupal–adult stages. Higher amounts of dAtx2‐B protein were detected in embryos, while dAtx2‐C protein was also expressed in higher levels in pupal–adult stages, indicating post‐transcriptional control for isoform B and transcription induction for isoform C, respectively. Moreover, in the fat body of L3 larvae dAtx2‐C, but not dAtx2‐B, accumulates in cytoplasmic foci that colocalize with sec23, a marker of endoplasmic reticulum exit sites (ERES). Interestingly, animals subjected to selective knockdown of dAtx2 in the larval fat body do not complete metamorphosis and die at the third larval stage or early puparium. Additionally, larvae knocked down for dAtx2, grown at 29 °C, are significantly smaller than control animals due to reduction in DNA replication and cell growth, which are consistent with the decreased levels of phosphorylated‐AKT observed in the fat body. Based on the localization of ataxin‐2 (dAtx2‐C) in ERESs, and on the phenotypes observed by dAtx2 knockdown in the larval fat body, we speculate a possible role for this protein in processes that regulate ERES formation. These data provide new insights into the biological function of ataxin‐2 with potential relevance to neurodegenerative diseases.

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Postplasmic/PEM RNAs: A class of localized maternal mRNAs with multiple roles in cell polarity and development in ascidian embryos

Prodon

Yamada

Shirae-Kurabayashi

et al. 2007

Developmental Dynamics

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Ascidian is a good model to understand the cellular and molecular mechanisms responsible for mRNA localization with the discovery of a large family of localized maternal mRNAs, called postplasmic/PEM RNAs, which includes more than 40 members in three different ascidian species (Halocynthia roretzi, Ciona intestinalis, and C. savignyi). Among these mRNAs, two types (Type I and Type II) have been identified and show two different localization patterns from fertilization to the eight-cell stage. At the eight-cell stage, both types concentrate to a macromolecular cortical structure called CAB (for Centrosome Attracting Body) in the posterior-vegetal B4.1 blastomeres. The CAB is responsible for unequal cleavages and the partitioning of postplasmic/PEM RNAs at the posterior pole of embryos during cleavage stages. It has also been suggested that the CAB region could contain putative germ granules. In this review, we discuss recent data obtained on the distribution of Type I postplasmic/PEM RNAs from oogenesis to late development, in relation to their localization and translational control. We have first regrouped localization patterns for Type I and Type II into a comparative diagram and included all important definitions in the field. We also have made an exhaustive classification of their embryonic expression profiles (Type I or Type II), and analyzed their functions after knockdown and/or overexpression experiments and the role of the 3-untranslated region (3UTR) controlling both their localization and translation. Finally, we propose a speculative model integrating recent data, and we also discuss the relationship between postplasmic/PEM RNAs, posterior specification, and germ cell formation in ascidians.

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Efficient Protein Trafficking Requires Trailer Hitch, a Component of a Ribonucleoprotein Complex Localized to the ER in Drosophila

Cited by 152 publications

References 57 publications

CPEB Interacts with an Ovary-specific eIF4E and 4E-T in Early Xenopus Oocytes

CPEB Interacts with an Ovary-specific eIF4E and 4E-T in Early Xenopus Oocytes

Drosophila ataxin‐2 gene encodes two differentially expressed isoforms and its function in larval fat body is crucial for development of peripheral tissues

Postplasmic/PEM RNAs: A class of localized maternal mRNAs with multiple roles in cell polarity and development in ascidian embryos

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