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Marhabaie M, Wharton TH, Kim SY, Wharton RP. Widespread regulation of the maternal transcriptome by Nanos in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555109. [PMID: 37693559 PMCID: PMC10491125 DOI: 10.1101/2023.08.28.555109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The translational repressor Nanos (Nos) regulates a single target, maternal hunchback (hb) mRNA, to govern abdominal segmentation in the early Drosophila embryo. Nos is recruited specifically to sites in the 3'-UTR of hb mRNA in collaboration with the sequence-specific RNA-binding protein Pumilio (Pum); on its own, Nos has no binding specificity. Nos is expressed at other stages of development, but very few mRNA targets that might mediate its action at these stages have been described. Nor has it been clear whether Nos is targeted to other mRNAs in concert with Pum or via other mechanisms. In this report, we identify mRNAs targeted by Nos via two approaches. In the first method, we identify mRNAs depleted upon expression of a chimera bearing Nos fused to the nonsense mediated decay (NMD) factor Upf1. We find that, in addition to hb, Upf1-Nos depletes ~2600 mRNAs from the maternal transcriptome in early embryos. Virtually all of these appear to be targeted in a canonical, hb-like manner in concert with Pum. In a second, more conventional approach, we identify mRNAs that are stabilized during the maternal zygotic transition (MZT) in embryos from nos- females. Most (86%) of the 1185 mRNAs regulated by Nos are also targeted by Upf1-Nos, validating use of the chimera. Approximately 60% of mRNAs targeted by Upf1-Nos are not stabilized in the absence of Nos. However, Upf1-Nos mRNA targets are hypo-adenylated and inefficiently translated at the ovary-embryo transition, whether or not they suffer Nos-dependent degradation in the embryo. We suggest that the late ovarian burst of Nos represses a large fraction of the maternal transcriptome, priming it for later degradation by other factors during the MZT in the embryo.
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Kozlov EN, Deev RV, Tokmatcheva EV, Tvorogova A, Kachaev ZM, Gilmutdinov RA, Zhukova M, Savvateeva-Popova EV, Schedl P, Shidlovskii YV. 3'UTR of mRNA Encoding CPEB Protein Orb2 Plays an Essential Role in Intracellular Transport in Neurons. Cells 2023; 12:1717. [PMID: 37443751 PMCID: PMC10340461 DOI: 10.3390/cells12131717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Intracellular trafficking plays a critical role in the functioning of highly polarized cells, such as neurons. Transport of mRNAs, proteins, and other molecules to synaptic terminals maintains contact between neurons and ensures the transmission of nerve impulses. Cytoplasmic polyadenylation element binding (CPEB) proteins play an essential role in long-term memory (LTM) formation by regulating local translation in synapses. Here, we show that the 3'UTR of the Drosophila CPEB gene orb2 is required for targeting the orb2 mRNA and protein to synapses and that this localization is important for LTM formation. When the orb2 3'UTR is deleted, the orb2 mRNAs and proteins fail to localize in synaptic fractions, and pronounced LTM deficits arise. We found that the phenotypic effects of the orb2 3'UTR deletion were rescued by introducing the 3'UTR from the orb, another Drosophila CPEB gene. In contrast, the phenotypic effects of the 3'UTR deletion were not rescued by the 3'UTR from one of the Drosophila α-tubulin genes. Our results show that the orb2 mRNAs must be targeted to the correct locations in neurons and that proper targeting depends upon sequences in the 3'UTR.
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Affiliation(s)
- Eugene N. Kozlov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
| | - Roman V. Deev
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
| | - Elena V. Tokmatcheva
- Institute of Physiology, Russian Academy of Sciences, 188680 St. Petersburg, Russia; (E.V.T.); (E.V.S.-P.)
| | - Anna Tvorogova
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia;
| | - Zaur M. Kachaev
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
| | - Rudolf A. Gilmutdinov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
| | - Mariya Zhukova
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
| | - Elena V. Savvateeva-Popova
- Institute of Physiology, Russian Academy of Sciences, 188680 St. Petersburg, Russia; (E.V.T.); (E.V.S.-P.)
| | - Paul Schedl
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA
| | - Yulii V. Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (E.N.K.); (R.V.D.); (Z.M.K.); (R.A.G.); (M.Z.); (P.S.)
- Department of Biology and General Genetics, Sechenov First Moscow State Medical University (Sechenov University), 119992 Moscow, Russia
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Bayer LV, Milano S, Formel SK, Kaur H, Ravichandran R, Cambeiro JA, Slinko L, Catrina IE, Bratu DP. Cup is essential for oskar mRNA translational repression during early Drosophila oogenesis. RNA Biol 2023; 20:573-587. [PMID: 37553798 PMCID: PMC10413924 DOI: 10.1080/15476286.2023.2242650] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/27/2023] [Accepted: 07/20/2023] [Indexed: 08/10/2023] Open
Abstract
Study of the timing and location for mRNA translation across model systems has begun to shed light on molecular events fundamental to such processes as intercellular communication, morphogenesis, and body pattern formation. In D. melanogaster, the posterior mRNA determinant, oskar, is transcribed maternally but translated only when properly localized at the oocyte's posterior cortex. Two effector proteins, Bruno1 and Cup, mediate steps of oskar mRNA regulation. The current model in the field identifies Bruno1 as necessary for Cup's recruitment to oskar mRNA and indispensable for oskar's translational repression. We now report that this Bruno1-Cup interaction leads to precise oskar mRNA regulation during early oogenesis and, importantly, the two proteins mutually influence each other's mRNA expression and protein distribution in the egg chamber. We show that these factors stably associate with oskar mRNA in vivo. Cup associates with oskar mRNA without Bruno1, while surprisingly Bruno1's stable association with oskar mRNA depends on Cup. We demonstrate that the essential factor for oskar mRNA repression in early oogenesis is Cup, not Bruno1. Furthermore, we find that Cup is a key P-body component that maintains functional P-body morphology during oogenesis and is necessary for oskar mRNA's association with P-bodies. Therefore, Cup drives the translational repression and stability of oskar mRNA. These experimental results point to a regulatory feedback loop between Bruno 1 and Cup in early oogenesis that appears crucial for oskar mRNA to reach the posterior pole and its expression in the egg chamber for accurate embryo development.
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Affiliation(s)
- Livia V. Bayer
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
- Program in Molecular, Cellular, and Developmental Biology, the Graduate Center, City University of New York, New York, NY, USA
| | - Samantha Milano
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
- Program in Molecular, Cellular, and Developmental Biology, the Graduate Center, City University of New York, New York, NY, USA
| | - Stephen K. Formel
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
| | - Harpreet Kaur
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
| | - Rishi Ravichandran
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
| | - Juan A. Cambeiro
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
| | - Lizaveta Slinko
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
| | - Irina E. Catrina
- Department of Chemistry and Biochemistry, Yeshiva University, New York, NY, USA
| | - Diana P. Bratu
- Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA
- Program in Molecular, Cellular, and Developmental Biology, the Graduate Center, City University of New York, New York, NY, USA
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Kenny A, Morgan MB, Macdonald PM. Different roles for the adjoining and structurally similar A-rich and poly(A) domains of oskar mRNA: Only the A-rich domain is required for oskar noncoding RNA function, which includes MTOC positioning. Dev Biol 2021; 476:117-127. [PMID: 33798537 DOI: 10.1016/j.ydbio.2021.03.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 11/17/2022]
Abstract
Drosophila oskar (osk) mRNA has both coding and noncoding functions, with the latter required for progression through oogenesis. Noncoding activity is mediated by the osk 3' UTR. Three types of cis elements act most directly and are clustered within the final ~120 nucleotides of the 3' UTR: multiple binding sites for the Bru1 protein, a short highly conserved region, and A-rich sequences abutting the poly(A) tail. Here we extend the characterization of these elements and their functions, providing new insights into osk noncoding RNA function and the makeup of the cis elements. We show that all three elements are required for correct positioning of the microtubule organizing center (MTOC), a defect not previously reported for any osk mutant. Normally, the MTOC is located at the posterior of the oocyte during previtellogenic stages of oogenesis, and this distribution underlies the strong posterior enrichment of many mRNAs transported into the oocyte from the nurse cells. When osk noncoding function was disrupted the MTOC was dispersed in the oocyte and osk mRNA failed to be enriched at the posterior, although transport to the oocyte was not affected. A previous study did not detect loss of posterior enrichment for certain osk mutants lacking noncoding activity (Kanke et al., 2015). This discrepancy may be due to use of imaging aimed at monitoring transport to the oocyte rather than posterior enrichment. Involvement in MTOC positioning suggests that the osk noncoding function may act in conjunction with genes whose loss has similar effects, and that osk function may extend to other processes requiring those genes. Further characterization of the cis elements required for osk noncoding function included completion of saturation mutagenesis of the most highly conserved region, providing critical information for evaluating the possible contribution of candidate binding factors. The 3'-most cis element is a cluster of A-rich sequences, the ARS. The close juxtaposition and structural similarity of the ARS and poly(A) tail raised the possibility that they comprise an extended A-rich element required for osk noncoding function. We found that absence of the poly(A) tail did not mimic the effects of mutation of the ARS, causing neither arrest of oogenesis nor mispositioning of osk mRNA in previtellogenic stage oocytes. Thus, the ARS and the poly(A) tail are not interchangeable for osk noncoding RNA function, suggesting that the role of the ARS is not in recruitment of Poly(A) binding protein (PABP), the protein that binds the poly(A) tail. Furthermore, although PABP has been implicated in transport of osk mRNA from the nurse cells to the oocyte, mutation of the ARS in combination with loss of the poly(A) tail did not disrupt transport of osk mRNA into the oocyte. We conclude that PABP acts indirectly in osk mRNA transport, or is associated with osk mRNA independent of an A-rich binding site. Although the poly(A) tail was not required for osk mRNA transport into the oocyte, its absence was associated with a novel osk mRNA localization defect later in oogenesis, potentially revealing a previously unrecognized step in the localization process.
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Affiliation(s)
- Andrew Kenny
- Department of Molecular Biosciences, The University of Texas at Austin, United States
| | - Miles B Morgan
- Department of Molecular Biosciences, The University of Texas at Austin, United States
| | - Paul M Macdonald
- Department of Molecular Biosciences, The University of Texas at Austin, United States.
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Dold A, Han H, Liu N, Hildebrandt A, Brüggemann M, Rücklé C, Hänel H, Busch A, Beli P, Zarnack K, König J, Roignant JY, Lasko P. Makorin 1 controls embryonic patterning by alleviating Bruno1-mediated repression of oskar translation. PLoS Genet 2020; 16:e1008581. [PMID: 31978041 PMCID: PMC7001992 DOI: 10.1371/journal.pgen.1008581] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 02/05/2020] [Accepted: 12/20/2019] [Indexed: 11/18/2022] Open
Abstract
Makorins are evolutionary conserved proteins that contain C3H-type zinc finger modules and a RING E3 ubiquitin ligase domain. In Drosophila, maternal Makorin 1 (Mkrn1) has been linked to embryonic patterning but the mechanism remained unsolved. Here, we show that Mkrn1 is essential for axis specification and pole plasm assembly by translational activation of oskar (osk). We demonstrate that Mkrn1 interacts with poly(A) binding protein (pAbp) and binds specifically to osk 3’ UTR in a region adjacent to A-rich sequences. Using Drosophila S2R+ cultured cells we show that this binding site overlaps with a Bruno1 (Bru1) responsive element (BREs) that regulates osk translation. We observe increased association of the translational repressor Bru1 with osk mRNA upon depletion of Mkrn1, indicating that both proteins compete for osk binding. Consistently, reducing Bru1 dosage partially rescues viability and Osk protein level in ovaries from Mkrn1 females. We conclude that Mkrn1 controls embryonic patterning and germ cell formation by specifically activating osk translation, most likely by competing with Bru1 to bind to osk 3’ UTR. To ensure accurate development of the Drosophila embryo, proteins and mRNAs are positioned at specific sites within the embryo. Many of these factors are produced and localized during the development of the egg in the mother. One protein essential for this process that has been heavily studied is Oskar (Osk), which is positioned at the posterior pole. During the localization of osk mRNA, its translation is repressed by the RNA-binding protein Bruno1 (Bru1), ensuring that Osk protein is not present outside of the posterior where it is harmful. At the posterior pole, osk mRNA is activated through mechanisms that are not yet understood. In this work, we show that the conserved protein Makorin 1 (Mkrn1) is a novel factor involved in the translational activation of osk. Mkrn1 binds specifically to osk mRNA, overlapping with a binding site of Bru1, thus alleviating the association of Bru1 with osk. Moreover, Mkrn1 is stabilized by poly(A) binding protein (pAbp), a translational activator that binds osk mRNA in close proximity to one Mkrn1 binding site. Our work thus helps to answer a long-standing question in the field, providing insight about the function of Mkrn1 and more generally into embryonic patterning in animals.
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Affiliation(s)
- Annabelle Dold
- RNA Epigenetics, Institute of Molecular Biology, Mainz, Germany
| | - Hong Han
- Department of Biology, McGill University, Montréal, Québec, Canada
| | - Niankun Liu
- Department of Biology, McGill University, Montréal, Québec, Canada
| | - Andrea Hildebrandt
- Chromatin Biology and Proteomics, Institute of Molecular Biology, Mainz, Germany.,Genomic Views of Splicing Regulation, Institute of Molecular Biology, Mainz, Germany
| | - Mirko Brüggemann
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Cornelia Rücklé
- Genomic Views of Splicing Regulation, Institute of Molecular Biology, Mainz, Germany.,Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Heike Hänel
- Genomic Views of Splicing Regulation, Institute of Molecular Biology, Mainz, Germany
| | - Anke Busch
- Bioinformatics Core Facility, Institute of Molecular Biology, Mainz, Germany
| | - Petra Beli
- Chromatin Biology and Proteomics, Institute of Molecular Biology, Mainz, Germany
| | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Julian König
- Genomic Views of Splicing Regulation, Institute of Molecular Biology, Mainz, Germany
| | - Jean-Yves Roignant
- RNA Epigenetics, Institute of Molecular Biology, Mainz, Germany.,Center for Integrative Genomics, Génopode Building, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Paul Lasko
- Department of Biology, McGill University, Montréal, Québec, Canada.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
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6
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Blatt P, Martin ET, Breznak SM, Rangan P. Post-transcriptional gene regulation regulates germline stem cell to oocyte transition during Drosophila oogenesis. Curr Top Dev Biol 2019; 140:3-34. [PMID: 32591078 DOI: 10.1016/bs.ctdb.2019.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
During oogenesis, several developmental processes must be traversed to ensure effective completion of gametogenesis including, stem cell maintenance and asymmetric division, differentiation, mitosis and meiosis, and production of maternally contributed mRNAs, making the germline a salient model for understanding how cell fate transitions are mediated. Due to silencing of the genome during meiotic divisions, there is little instructive transcription, barring a few examples, to mediate these critical transitions. In Drosophila, several layers of post-transcriptional regulation ensure that the mRNAs required for these processes are expressed in a timely manner and as needed during germline differentiation. These layers of regulation include alternative splicing, RNA modification, ribosome production, and translational repression. Many of the molecules and pathways involved in these regulatory activities are conserved from Drosophila to humans making the Drosophila germline an elegant model for studying the role of post-transcriptional regulation during stem cell differentiation and meiosis.
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Affiliation(s)
- Patrick Blatt
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, NY, United States; University at Albany SUNY, Albany, NY, United States
| | - Elliot T Martin
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, NY, United States; University at Albany SUNY, Albany, NY, United States
| | - Shane M Breznak
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, NY, United States; University at Albany SUNY, Albany, NY, United States
| | - Prashanth Rangan
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, NY, United States; University at Albany SUNY, Albany, NY, United States.
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7
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Subcellular Specialization and Organelle Behavior in Germ Cells. Genetics 2018; 208:19-51. [PMID: 29301947 DOI: 10.1534/genetics.117.300184] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 08/17/2017] [Indexed: 11/18/2022] Open
Abstract
Gametes, eggs and sperm, are the highly specialized cell types on which the development of new life solely depends. Although all cells share essential organelles, such as the ER (endoplasmic reticulum), Golgi, mitochondria, and centrosomes, germ cells display unique regulation and behavior of organelles during gametogenesis. These germ cell-specific functions of organelles serve critical roles in successful gamete production. In this chapter, I will review the behaviors and roles of organelles during germ cell differentiation.
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Wharton TH, Nomie KJ, Wharton RP. No significant regulation of bicoid mRNA by Pumilio or Nanos in the early Drosophila embryo. PLoS One 2018; 13:e0194865. [PMID: 29601592 PMCID: PMC5877865 DOI: 10.1371/journal.pone.0194865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/12/2018] [Indexed: 01/23/2023] Open
Abstract
Drosophila Pumilio (Pum) is a founding member of the conserved Puf domain class of RNA-binding translational regulators. Pum binds with high specificity, contacting eight nucleotides, one with each of the repeats in its RNA-binding domain. In general, Pum is thought to block translation in collaboration with Nanos (Nos), which exhibits no binding specificity in isolation but is recruited jointly to regulatory sequences containing a Pum binding site in the 3’-UTRs of target mRNAs. Unlike Pum, which is ubiquitous in the early embryo, Nos is tightly restricted to the posterior, ensuring that repression of its best-characterized target, maternal hunchback (hb) mRNA, takes place exclusively in the posterior. An exceptional case of Nos-independent regulation by Pum has been described—repression of maternal bicoid (bcd) mRNA at the anterior pole of the early embryo, dependent on both Pum and conserved Pum binding sites in the 3’-UTR of the mRNA. We have re-investigated regulation of bcd in the early embryo; our experiments reveal no evidence of a role for Pum or its conserved binding sites in regulation of the perdurance of bcd mRNA or protein. Instead, we find that Pum and Nos control the accumulation of bcd mRNA in testes.
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Affiliation(s)
- Tammy H. Wharton
- Departments of Molecular Genetics & Cancer Biology and Genetics, Center for RNA Biology Ohio State University Columbus, OH
| | - Krystle J. Nomie
- Department of Lymphoma/Myeloma MD Anderson Cancer Center Holcombe Blvd. Houston, TX
| | - Robin P. Wharton
- Departments of Molecular Genetics & Cancer Biology and Genetics, Center for RNA Biology Ohio State University Columbus, OH
- * E-mail:
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9
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Ryu YH, Kenny A, Gim Y, Snee M, Macdonald PM. Multiple cis-acting signals, some weak by necessity, collectively direct robust transport of oskar mRNA to the oocyte. J Cell Sci 2017; 130:3060-3071. [PMID: 28760927 DOI: 10.1242/jcs.202069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 07/24/2017] [Indexed: 10/19/2022] Open
Abstract
Localization of mRNAs can involve multiple steps, each with its own cis-acting localization signals and transport factors. How is the transition between different steps orchestrated? We show that the initial step in localization of Drosophila oskar mRNA - transport from nurse cells to the oocyte - relies on multiple cis-acting signals. Some of these are binding sites for the translational control factor Bruno, suggesting that Bruno plays an additional role in mRNA transport. Although transport of oskar mRNA is essential and robust, the localization activity of individual transport signals is weak. Notably, increasing the strength of individual transport signals, or adding a strong transport signal, disrupts the later stages of oskar mRNA localization. We propose that the oskar transport signals are weak by necessity; their weakness facilitates transfer of the oskar mRNA from the oocyte transport machinery to the machinery for posterior localization.
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Affiliation(s)
- Young Hee Ryu
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Andrew Kenny
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Youme Gim
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mark Snee
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Paul M Macdonald
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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10
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Johnston WL, Krizus A, Ramani AK, Dunham W, Youn JY, Fraser AG, Gingras AC, Dennis JW. C. elegans SUP-46, an HNRNPM family RNA-binding protein that prevents paternally-mediated epigenetic sterility. BMC Biol 2017; 15:61. [PMID: 28716093 PMCID: PMC5513350 DOI: 10.1186/s12915-017-0398-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/21/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND In addition to DNA, gametes contribute epigenetic information in the form of histones and non-coding RNA. Epigenetic programs often respond to stressful environmental conditions and provide a heritable history of ancestral stress that allows for adaptation and propagation of the species. In the nematode C. elegans, defective epigenetic transmission often manifests as progressive germline mortality. We previously isolated sup-46 in a screen for suppressors of the hexosamine pathway gene mutant, gna-2(qa705). In this study, we examine the role of SUP-46 in stress resistance and progressive germline mortality. RESULTS We identified SUP-46 as an HNRNPM family RNA-binding protein, and uncovered a highly novel role for SUP-46 in preventing paternally-mediated progressive germline mortality following mating. Proximity biotinylation profiling of human homologs (HNRNPM, MYEF2) identified proteins of ribonucleoprotein complexes previously shown to contain non-coding RNA. Like HNRNPM and MYEF2, SUP-46 was associated with multiple RNA granules, including stress granules, and also formed granules on active chromatin. SUP-46 depletion disrupted germ RNA granules and caused ectopic sperm, increased sperm transcripts, and chronic heat stress sensitivity. SUP-46 was also required for resistance to acute heat stress, and a conserved "MYEF2" motif was identified that was needed for stress resistance. CONCLUSIONS In mammals, non-coding RNA from the sperm of stressed males has been shown to recapitulate paternal stress phenotypes in the offspring. Our results suggest that HNRNPM family proteins enable stress resistance and paternally-mediated epigenetic transmission that may be conserved across species.
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Affiliation(s)
- Wendy L. Johnston
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON Canada
| | - Aldis Krizus
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON Canada
| | - Arun K. Ramani
- Centre for Computational Medicine, The Hospital for Sick Children, Toronto, ON Canada
| | - Wade Dunham
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON Canada
| | - Ji Young Youn
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON Canada
| | - Andrew G. Fraser
- Department of Molecular Genetics, University of Toronto, Toronto, ON Canada
- The Donnelly Centre, University of Toronto, Toronto, ON Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON Canada
| | - James W. Dennis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON Canada
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11
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Aguilera-Gomez A, Rabouille C. Membrane-bound organelles versus membrane-less compartments and their control of anabolic pathways in Drosophila. Dev Biol 2017; 428:310-317. [PMID: 28377034 DOI: 10.1016/j.ydbio.2017.03.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/27/2017] [Accepted: 03/27/2017] [Indexed: 12/29/2022]
Abstract
Classically, we think of cell compartmentalization as being achieved by membrane-bound organelles. It has nevertheless emerged that membrane-less assemblies also largely contribute to this compartmentalization. Here, we compare the characteristics of both types of compartmentalization in term of maintenance of functional identities. Furthermore, membrane less-compartments are critical for sustaining developmental and cell biological events as they control major metabolic pathways. We describe two examples related to this issue in Drosophila, the role of P-bodies in the translational control of gurken in the Drosophila oocyte, and the formation of Sec bodies upon amino-acid starvation in Drosophila cells.
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Affiliation(s)
| | - Catherine Rabouille
- Hubrecht Institute of the KNAW & UMC Utrecht, 3584 CT Utrecht, The Netherlands; Department of Cell Biology, UMC Utrecht, The Netherlands; Department of Cell Biology, UMC Groningen, The Netherlands.
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Macdonald PM, Kanke M, Kenny A. Community effects in regulation of translation. eLife 2016; 5:e10965. [PMID: 27104756 PMCID: PMC4846370 DOI: 10.7554/elife.10965] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 03/18/2016] [Indexed: 12/27/2022] Open
Abstract
Certain forms of translational regulation, and translation itself, rely on long-range interactions between proteins bound to the different ends of mRNAs. A widespread assumption is that such interactions occur only in cis, between the two ends of a single transcript. However, certain translational regulatory defects of the Drosophila oskar (osk) mRNA can be rescued in trans. We proposed that inter-transcript interactions, promoted by assembly of the mRNAs in particles, allow regulatory elements to act in trans. Here we confirm predictions of that model and show that disruption of PTB-dependent particle assembly inhibits rescue in trans. Communication between transcripts is not limited to different osk mRNAs, as regulation imposed by cis-acting elements embedded in the osk mRNA spreads to gurken mRNA. We conclude that community effects exist in translational regulation. DOI:http://dx.doi.org/10.7554/eLife.10965.001 Genes encode the instructions needed to make proteins and other molecules. To make a protein, the DNA within a gene is copied to produce molecules of messenger ribonucleic acid (mRNA) that are then used as templates to build proteins via a process called translation. This process – which involves protein machines called ribosomes binding to the start of the mRNA – is tightly regulated to control the amounts of particular proteins in cells. For example, in fruit fly ovaries, a protein called Bruno both represses and activates the translation of a gene known as oskar. To achieve this, Bruno binds to regions near the end of the oskar RNA known as Bruno response elements. It is not clear how Bruno acts to control translation. However, because ribosomes begin translation near the start of the mRNA, while Bruno is bound to regions near the end of the mRNA, there must be long-range interactions between the two ends of the mRNA. It is generally assumed that such long-range interactions only occur between proteins that are bound to the same mRNA molecule. However, in 2010, researchers observed that Bruno response elements within one oskar mRNA could influence the translation of other oskar mRNAs. This is known as “regulation in trans”. Here, Macdonald et al. – including some of the researchers from the earlier work – investigated this observation in more detail in fruit flies. In cells, multiple mRNA molecules and their associated proteins can assemble into particles. Macdonald et al. proposed that the close proximity of many mRNA molecules in these particles could allow trans regulation to take place. Indeed, the experiments found that blocking the assembly of oskar mRNA into particles inhibited trans regulation as expected. Macdonald et al. also asked if trans regulation can occur between mRNAs that encode different proteins. The experiments show that oskar mRNA could block the translation of an mRNA produced by the gurken gene, even when oskar mRNA was not being translated. More work is needed to find out how widely trans regulation is used to control translation. DOI:http://dx.doi.org/10.7554/eLife.10965.002
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Affiliation(s)
- Paul M Macdonald
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, United States
| | - Matt Kanke
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, United States
| | - Andrew Kenny
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, United States
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Localized Translation of gurken/TGF-α mRNA during Axis Specification Is Controlled by Access to Orb/CPEB on Processing Bodies. Cell Rep 2016; 14:2451-62. [PMID: 26947065 PMCID: PMC4823467 DOI: 10.1016/j.celrep.2016.02.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/18/2015] [Accepted: 02/03/2016] [Indexed: 12/31/2022] Open
Abstract
In Drosophila oocytes, gurken/TGF-α mRNA is essential for establishing the future embryonic axes. gurken remains translationally silent during transport from its point of synthesis in nurse cells to its final destination in the oocyte, where it associates with the edge of processing bodies. Here we show that, in nurse cells, gurken is kept translationally silent by the lack of sufficient Orb/CPEB, its translational activator. Processing bodies in nurse cells have a similar protein complement and ultrastructure to those in the oocyte, but they markedly less Orb and do not associate with gurken mRNA. Ectopic expression of Orb in nurse cells at levels similar to the wild-type oocyte dorso-anterior corner at mid-oogenesis is sufficient to cause gurken mRNA to associate with processing bodies and translate prematurely. We propose that controlling the spatial distribution of translational activators is a fundamental mechanism for regulating localized translation. gurken mRNA is not silenced by known repressors during its transport In nurse cells, gurken mRNA is not associated with processing bodies In nurse cells, lack of sufficient Orb/CPEB silences gurken mRNA translation In oocytes, gurken mRNA is associated with Orb on processing bodies and translated
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Ryu YH, Macdonald PM. RNA sequences required for the noncoding function of oskar RNA also mediate regulation of Oskar protein expression by Bicoid Stability Factor. Dev Biol 2015; 407:211-23. [PMID: 26433064 DOI: 10.1016/j.ydbio.2015.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/13/2015] [Accepted: 09/24/2015] [Indexed: 10/23/2022]
Abstract
The Drosophila oskar (osk) mRNA is unusual in having both coding and noncoding functions. As an mRNA, osk encodes a protein which is deployed specifically at the posterior of the oocyte. This spatially-restricted deployment relies on a program of mRNA localization and both repression and activation of translation, all dependent on regulatory elements located primarily in the 3' untranslated region (UTR) of the mRNA. The 3' UTR also mediates the noncoding function of osk, which is essential for progression through oogenesis. Mutations which most strongly disrupt the noncoding function are positioned in a short region (the C region) near the 3' end of the mRNA, in close proximity to elements required for activation of translation. We show that Bicoid Stability Factor (BSF) binds specifically to the C region of the mRNA. Both knockdown of bsf and mutation of BSF binding sites in osk mRNA have the same consequences: Osk expression is largely eliminated late in oogenesis, with both mRNA localization and translation disrupted. Although the C region of the osk 3' UTR is required for the noncoding function, BSF binding does not appear to be essential for that function.
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Affiliation(s)
- Young Hee Ryu
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Paul M Macdonald
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
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15
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Kanke M, Jambor H, Reich J, Marches B, Gstir R, Ryu YH, Ephrussi A, Macdonald PM. oskar RNA plays multiple noncoding roles to support oogenesis and maintain integrity of the germline/soma distinction. RNA (NEW YORK, N.Y.) 2015; 21:1096-109. [PMID: 25862242 PMCID: PMC4436663 DOI: 10.1261/rna.048298.114] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/12/2015] [Indexed: 05/05/2023]
Abstract
The Drosophila oskar (osk) mRNA is unusual in that it has both coding and noncoding functions. As an mRNA, osk encodes a protein required for embryonic patterning and germ cell formation. Independent of that function, the absence of osk mRNA disrupts formation of the karyosome and blocks progression through oogenesis. Here we show that loss of osk mRNA also affects the distribution of regulatory proteins, relaxing their association with large RNPs within the germline, and allowing them to accumulate in the somatic follicle cells. This and other noncoding functions of the osk mRNA are mediated by multiple sequence elements with distinct roles. One role, provided by numerous binding sites in two distinct regions of the osk 3' UTR, is to sequester the translational regulator Bruno (Bru), which itself controls translation of osk mRNA. This defines a novel regulatory circuit, with Bru restricting the activity of osk, and osk in turn restricting the activity of Bru. Other functional elements, which do not bind Bru and are positioned close to the 3' end of the RNA, act in the oocyte and are essential. Despite the different roles played by the different types of elements contributing to RNA function, mutation of any leads to accumulation of the germline regulatory factors in the follicle cells.
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Affiliation(s)
- Matt Kanke
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Helena Jambor
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - John Reich
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Brittany Marches
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Ronald Gstir
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Young Hee Ryu
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Anne Ephrussi
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Paul M Macdonald
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
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Kim G, Pai CI, Sato K, Person MD, Nakamura A, Macdonald PM. Region-specific activation of oskar mRNA translation by inhibition of Bruno-mediated repression. PLoS Genet 2015; 11:e1004992. [PMID: 25723530 PMCID: PMC4344327 DOI: 10.1371/journal.pgen.1004992] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/07/2015] [Indexed: 11/18/2022] Open
Abstract
A complex program of translational repression, mRNA localization, and translational activation ensures that Oskar (Osk) protein accumulates only at the posterior pole of the Drosophila oocyte. Inappropriate expression of Osk disrupts embryonic axial patterning, and is lethal. A key factor in translational repression is Bruno (Bru), which binds to regulatory elements in the osk mRNA 3' UTR. After posterior localization of osk mRNA, repression by Bru must be alleviated. Here we describe an in vivo assay system to monitor the spatial pattern of Bru-dependent repression, separate from the full complexity of osk regulation. This assay reveals a form of translational activation-region-specific activation-which acts regionally in the oocyte, is not mechanistically coupled to mRNA localization, and functions by inhibiting repression by Bru. We also show that Bru dimerizes and identify mutations that disrupt this interaction to test its role in vivo. Loss of dimerization does not disrupt repression, as might have been expected from an existing model for the mechanism of repression. However, loss of dimerization does impair regional activation of translation, suggesting that dimerization may constrain, not promote, repression. Our work provides new insight into the question of how localized mRNAs become translationally active, showing that repression of osk mRNA is locally inactivated by a mechanism acting independent of mRNA localization.
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Affiliation(s)
- Goheun Kim
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Chin-I Pai
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Keiji Sato
- Laboratory for Germline Development, RIKEN Center for Developmental Biology, Kobe, Hyogo, Japan
| | - Maria D. Person
- Proteomics Facility, Institute for Cellular and Molecular Biology and College of Pharmacy, The University of Texas at Austin, Austin, Texas, United States of America
| | - Akira Nakamura
- Department of Germline Development, Division of Organogenesis, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Paul M. Macdonald
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Molecular characterization of Plasmodium falciparum Bruno/CELF RNA binding proteins. Mol Biochem Parasitol 2014; 198:1-10. [DOI: 10.1016/j.molbiopara.2014.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 10/13/2014] [Accepted: 10/22/2014] [Indexed: 01/04/2023]
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Vlasova-St Louis I, Dickson AM, Bohjanen PR, Wilusz CJ. CELFish ways to modulate mRNA decay. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:695-707. [PMID: 23328451 DOI: 10.1016/j.bbagrm.2013.01.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/03/2013] [Accepted: 01/05/2013] [Indexed: 12/14/2022]
Abstract
The CELF family of RNA-binding proteins regulates many steps of mRNA metabolism. Although their best characterized function is in pre-mRNA splice site choice, CELF family members are also powerful modulators of mRNA decay. In this review we focus on the different modes of regulation that CELF proteins employ to mediate mRNA decay by binding to GU-rich elements. After starting with an overview of the importance of CELF proteins during development and disease pathogenesis, we then review the mRNA networks and cellular pathways these proteins regulate and the mechanisms by which they influence mRNA decay. Finally, we discuss how CELF protein activity is modulated during development and in response to cellular signals. We conclude by highlighting the priorities for new experiments in this field. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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