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Barr J, Diegmiller R, Colonnetta MM, Ke W, Imran Alsous J, Stern T, Shvartsman SY, Schedl P. To be or not to be: orb, the fusome and oocyte specification in Drosophila. Genetics 2024; 226:iyae020. [PMID: 38345426 PMCID: PMC10990432 DOI: 10.1093/genetics/iyae020] [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: 12/17/2023] [Accepted: 01/21/2024] [Indexed: 04/05/2024] Open
Abstract
In the fruit fly Drosophila melanogaster, two cells in a cyst of 16 interconnected cells have the potential to become the oocyte, but only one of these will assume an oocyte fate as the cysts transition through regions 2a and 2b of the germarium. The mechanism of specification depends on a polarized microtubule network, a dynein dependent Egl:BicD mRNA cargo complex, a special membranous structure called the fusome and its associated proteins, and the translational regulator orb. In this work, we have investigated the role of orb and the fusome in oocyte specification. We show here that specification is a stepwise process. Initially, orb mRNAs accumulate in the two pro-oocytes in close association with the fusome. This association is accompanied by the activation of the orb autoregulatory loop, generating high levels of Orb. Subsequently, orb mRNAs become enriched in only one of the pro-oocytes, the presumptive oocyte, and this is followed, with a delay, by Orb localization to the oocyte. We find that fusome association of orb mRNAs is essential for oocyte specification in the germarium, is mediated by the orb 3' UTR, and requires Orb protein. We also show that the microtubule minus end binding protein Patronin functions downstream of orb in oocyte specification. Finally, in contrast to a previously proposed model for oocyte selection, we find that the choice of which pro-oocyte becomes the oocyte does not seem to be predetermined by the amount of fusome material in these two cells, but instead depends upon a competition for orb gene products.
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Affiliation(s)
- Justinn Barr
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Rocky Diegmiller
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Megan M Colonnetta
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Wenfan Ke
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Jasmin Imran Alsous
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Flatiron Institute, Simons Foundation, New York, NY 10010, USA
| | - Tomer Stern
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Stanislav Y Shvartsman
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Flatiron Institute, Simons Foundation, New York, NY 10010, USA
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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2
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Jejina A, Ayala Y, Beuchle D, Höhener T, Dörig RE, Vazquez-Pianzola P, Hernández G, Suter B. Role of BicDR in bristle shaft construction and support of BicD functions. J Cell Sci 2024; 137:jcs261408. [PMID: 38264934 PMCID: PMC10917063 DOI: 10.1242/jcs.261408] [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: 06/16/2023] [Accepted: 12/15/2023] [Indexed: 01/25/2024] Open
Abstract
Cell polarization requires asymmetric localization of numerous mRNAs, proteins and organelles. The movement of cargo towards the minus end of microtubules mostly depends on cytoplasmic dynein motors. In the dynein-dynactin-Bicaudal-D transport machinery, Bicaudal-D (BicD) links the cargo to the motor. Here, we focus on the role of Drosophila BicD-related (BicDR, CG32137) in the development of the long bristles. Together with BicD, it contributes to the organization and stability of the actin cytoskeleton in the not-yet-chitinized bristle shaft. BicD and BicDR also support the stable expression and distribution of Rab6 and Spn-F in the bristle shaft, including the distal tip localization of Spn-F, pointing to the role of microtubule-dependent vesicle trafficking for bristle construction. BicDR supports the function of BicD, and we discuss the hypothesis whereby BicDR might transport cargo more locally, with BicD transporting cargo over long distances, such as to the distal tip. We also identified embryonic proteins that interact with BicDR and appear to be BicDR cargo. For one of them, EF1γ (also known as eEF1γ), we show that the encoding gene EF1γ interacts with BicD and BicDR in the construction of the bristles.
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Affiliation(s)
- Aleksandra Jejina
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Yeniffer Ayala
- Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer, Instituto Nacional de Cancerologıá (INCan), 14080 Tlalpan, Mexico City, Mexico
| | - Dirk Beuchle
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | - Thomas Höhener
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | - Ruth E. Dörig
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | | | - Greco Hernández
- Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer, Instituto Nacional de Cancerologıá (INCan), 14080 Tlalpan, Mexico City, Mexico
| | - Beat Suter
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
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3
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Ruffinatti FA, Scarpellino G, Chinigò G, Visentin L, Munaron L. The Emerging Concept of Transportome: State of the Art. Physiology (Bethesda) 2023; 38:0. [PMID: 37668550 DOI: 10.1152/physiol.00010.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 09/01/2023] [Accepted: 09/01/2023] [Indexed: 09/06/2023] Open
Abstract
The array of ion channels and transporters expressed in cell membranes, collectively referred to as the transportome, is a complex and multifunctional molecular machinery; in particular, at the plasma membrane level it finely tunes the exchange of biomolecules and ions, acting as a functionally adaptive interface that accounts for dynamic plasticity in the response to environmental fluctuations and stressors. The transportome is responsible for the definition of membrane potential and its variations, participates in the transduction of extracellular signals, and acts as a filter for most of the substances entering and leaving the cell, thus enabling the homeostasis of many cellular parameters. For all these reasons, physiologists have long been interested in the expression and functionality of ion channels and transporters, in both physiological and pathological settings and across the different domains of life. Today, thanks to the high-throughput technologies of the postgenomic era, the omics approach to the study of the transportome is becoming increasingly popular in different areas of biomedical research, allowing for a more comprehensive, integrated, and functional perspective of this complex cellular apparatus. This article represents a first effort for a systematic review of the scientific literature on this topic. Here we provide a brief overview of all those studies, both primary and meta-analyses, that looked at the transportome as a whole, regardless of the biological problem or the models they used. A subsequent section is devoted to the methodological aspect by reviewing the most important public databases annotating ion channels and transporters, along with the tools they provide to retrieve such information. Before conclusions, limitations and future perspectives are also discussed.
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Affiliation(s)
- Federico Alessandro Ruffinatti
- Turin Cell Physiology Laboratory (TCP-Lab), Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Giorgia Scarpellino
- Turin Cell Physiology Laboratory (TCP-Lab), Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Giorgia Chinigò
- Turin Cell Physiology Laboratory (TCP-Lab), Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Luca Visentin
- Turin Cell Physiology Laboratory (TCP-Lab), Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Luca Munaron
- Turin Cell Physiology Laboratory (TCP-Lab), Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
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4
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Lu W, Lakonishok M, Gelfand VI. The dynamic duo of microtubule polymerase Mini spindles/XMAP215 and cytoplasmic dynein is essential for maintaining Drosophila oocyte fate. Proc Natl Acad Sci U S A 2023; 120:e2303376120. [PMID: 37722034 PMCID: PMC10523470 DOI: 10.1073/pnas.2303376120] [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: 02/27/2023] [Accepted: 07/11/2023] [Indexed: 09/20/2023] Open
Abstract
In many species, only one oocyte is specified among a group of interconnected germline sister cells. In Drosophila melanogaster, 16 interconnected cells form a germline cyst, where one cell differentiates into an oocyte, while the rest become nurse cells that supply the oocyte with mRNAs, proteins, and organelles through intercellular cytoplasmic bridges named ring canals via microtubule-based transport. In this study, we find that a microtubule polymerase Mini spindles (Msps), the Drosophila homolog of XMAP215, is essential for maintenance of the oocyte specification. mRNA encoding Msps is transported and concentrated in the oocyte by dynein-dependent transport along microtubules. Translated Msps stimulates microtubule polymerization in the oocyte, causing more microtubule plus ends to grow from the oocyte through the ring canals into nurse cells, further enhancing nurse cell-to-oocyte transport by dynein. Knockdown of msps blocks the oocyte growth and causes gradual loss of oocyte determinants. Thus, the Msps-dynein duo creates a positive feedback loop, ensuring oocyte fate maintenance by promoting high microtubule polymerization activity in the oocyte, and enhancing dynein-dependent nurse cell-to-oocyte transport.
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Affiliation(s)
- Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Margot Lakonishok
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Vladimir I. Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
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5
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Neiswender H, Baker FC, Veeranan-Karmegam R, Allen P, Gonsalvez GB. dTtc1, a conserved tetratricopeptide repeat protein, is required for maturation of Drosophila egg chambers via its role in stabilizing electron transport chain components. Front Cell Dev Biol 2023; 11:1148773. [PMID: 37333987 PMCID: PMC10272552 DOI: 10.3389/fcell.2023.1148773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/18/2023] [Indexed: 06/20/2023] Open
Abstract
We recently identified the Drosophila ortholog of TTC1 (dTtc1) as an interacting partner of Egalitarian, an RNA adaptor of the Dynein motor. In order to better understand the function of this relatively uncharacterized protein, we depleted dTtc1 in the Drosophila female germline. Depletion of dTtc1 resulted in defective oogenesis and no mature eggs were produced. A closer examination revealed that mRNA cargoes normally transported by Dynein were relatively unaffected. However, mitochondria in dTtc1 depleted egg chambers displayed an extremely swollen phenotype. Ultrastructural analysis revealed a lack of cristae. These phenotypes were not observed upon disruption of Dynein. Thus, this function of dTtc1 is likely to be Dynein independent. Consistent with a role for dTtc1 in mitochondrial biology, a published proteomics screen revealed that dTtc1 interacts with numerous components of electron transport chain (ETC) complexes. Our results indicate that the expression level of several of these ETC components was significantly reduced upon depletion of dTtc1. Importantly, this phenotype was completely rescued upon expression of wild-type GFP-dTtc1 in the depleted background. Lastly, we demonstrate that the mitochondrial phenotype caused by a lack of dTtc1 is not restricted to the germline but is also observed in somatic tissues. Our model suggests that dTtc1, likely in combination with cytoplasmic chaperones, is required for stabilizing ETC components.
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6
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Lu W, Lakonishok M, Gelfand VI. Drosophila oocyte specification is maintained by the dynamic duo of microtubule polymerase Mini spindles/XMAP215 and dynein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.09.531953. [PMID: 36945460 PMCID: PMC10028982 DOI: 10.1101/2023.03.09.531953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
In many species, only one oocyte is specified among a group of interconnected germline sister cells. In Drosophila melanogaster , 16-cell interconnected cells form a germline cyst, where one cell differentiates into an oocyte, while the rest become nurse cells that supply the oocyte with mRNAs, proteins, and organelles through intercellular cytoplasmic bridges named ring canals via microtubule-based transport. In this study, we find that a microtubule polymerase Mini spindles (Msps), the Drosophila homolog of XMAP215, is essential for the oocyte fate determination. mRNA encoding Msps is concentrated in the oocyte by dynein-dependent transport along microtubules. Translated Msps stimulates microtubule polymerization in the oocyte, causing more microtubule plus ends to grow from the oocyte through the ring canals into nurse cells, further enhancing nurse cell-to-oocyte transport by dynein. Knockdown of msps blocks the oocyte growth and causes gradual loss of oocyte determinants. Thus, the Msps-dynein duo creates a positive feedback loop, enhancing dynein-dependent nurse cell-to-oocyte transport and transforming a small stochastic difference in microtubule polarity among sister cells into a clear oocyte fate determination. Significance statement Oocyte determination in Drosophila melanogaster provides a valuable model for studying cell fate specification. We describe the crucial role of the duo of microtubule polymerase Mini spindles (Msps) and cytoplasmic dynein in this process. We show that Msps is essential for oocyte fate determination. Msps concentration in the oocyte is achieved through dynein-dependent transport of msps mRNA along microtubules. Translated Msps stimulates microtubule polymerization in the oocyte, further enhancing nurse cell-to-oocyte transport by dynein. This creates a positive feedback loop that transforms a small stochastic difference in microtubule polarity among sister cells into a clear oocyte fate determination. Our findings provide important insights into the mechanisms of oocyte specification and have implications for understanding the development of multicellular organisms.
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Affiliation(s)
- Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Margot Lakonishok
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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7
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Yi J, Zhao X, Noell CR, Helmer P, Solmaz SR, Vallee RB. Role of Nesprin-2 and RanBP2 in BICD2-associated brain developmental disorders. PLoS Genet 2023; 19:e1010642. [PMID: 36930595 PMCID: PMC10022797 DOI: 10.1371/journal.pgen.1010642] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/28/2023] [Indexed: 03/18/2023] Open
Abstract
Bicaudal D2 (BICD2) is responsible for recruiting cytoplasmic dynein to diverse forms of subcellular cargo for their intracellular transport. Mutations in the human BICD2 gene have been found to cause an autosomal dominant form of spinal muscular atrophy (SMA-LED2), and brain developmental defects. Whether and how the latter mutations are related to roles we and others have identified for BICD2 in brain development remains little understood. BICD2 interacts with the nucleoporin RanBP2 to recruit dynein to the nuclear envelope (NE) of Radial Glial Progenitor cells (RGPs) to mediate their well-known but mysterious cell-cycle-regulated interkinetic nuclear migration (INM) behavior, and their subsequent differentiation to form cortical neurons. We more recently found that BICD2 also mediates NE dynein recruitment in migrating post-mitotic neurons, though via a different interactor, Nesprin-2. Here, we report that Nesprin-2 and RanBP2 compete for BICD2-binding in vitro. To test the physiological implications of this behavior, we examined the effects of known BICD2 mutations using in vitro biochemical and in vivo electroporation-mediated brain developmental assays. We find a clear relationship between the ability of BICD2 to bind RanBP2 vs. Nesprin-2 in controlling of nuclear migration and neuronal migration behavior. We propose that mutually exclusive RanBP2-BICD2 vs. Nesprin-2-BICD2 interactions at the NE play successive, critical roles in INM behavior in RGPs and in post-mitotic neuronal migration and errors in these processes contribute to specific human brain malformations.
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Affiliation(s)
- Julie Yi
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
| | - Xiaoxin Zhao
- Department of Chemistry, Binghamton University, Binghamton, New York, New York, United States of America
| | - Crystal R. Noell
- Department of Chemistry, Binghamton University, Binghamton, New York, New York, United States of America
| | - Paige Helmer
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
| | - Sozanne R. Solmaz
- Department of Chemistry, Binghamton University, Binghamton, New York, New York, United States of America
| | - Richard B. Vallee
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
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8
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Subcellular spatial transcriptomics identifies three mechanistically different classes of localizing RNAs. Nat Commun 2022; 13:6355. [PMID: 36289223 PMCID: PMC9606379 DOI: 10.1038/s41467-022-34004-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 10/03/2022] [Indexed: 12/25/2022] Open
Abstract
Intracellular RNA localization is a widespread and dynamic phenomenon that compartmentalizes gene expression and contributes to the functional polarization of cells. Thus far, mechanisms of RNA localization identified in Drosophila have been based on a few RNAs in different tissues, and a comprehensive mechanistic analysis of RNA localization in a single tissue is lacking. Here, by subcellular spatial transcriptomics we identify RNAs localized in the apical and basal domains of the columnar follicular epithelium (FE) and we analyze the mechanisms mediating their localization. Whereas the dynein/BicD/Egl machinery controls apical RNA localization, basally-targeted RNAs require kinesin-1 to overcome a default dynein-mediated transport. Moreover, a non-canonical, translation- and dynein-dependent mechanism mediates apical localization of a subgroup of dynein-activating adaptor-encoding RNAs (BicD, Bsg25D, hook). Altogether, our study identifies at least three mechanisms underlying RNA localization in the FE, and suggests a possible link between RNA localization and dynein/dynactin/adaptor complex formation in vivo.
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9
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Vazquez-Pianzola P, Beuchle D, Saro G, Hernández G, Maldonado G, Brunßen D, Meister P, Suter B. Female meiosis II and pronuclear fusion require the microtubule transport factor Bicaudal D. Development 2022; 149:275749. [DOI: 10.1242/dev.199944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 05/25/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Bicaudal D (BicD) is a dynein adaptor that transports different cargoes along microtubules. Reducing the activity of BicD specifically in freshly laid Drosophila eggs by acute protein degradation revealed that BicD is needed to produce normal female meiosis II products, to prevent female meiotic products from re-entering the cell cycle, and for pronuclear fusion. Given that BicD is required to localize the spindle assembly checkpoint (SAC) components Mad2 and BubR1 to the female meiotic products, it appears that BicD functions to localize these components to control metaphase arrest of polar bodies. BicD interacts with Clathrin heavy chain (Chc), and both proteins localize to centrosomes, mitotic spindles and the tandem spindles during female meiosis II. Furthermore, BicD is required to localize clathrin and the microtubule-stabilizing factors transforming acidic coiled-coil protein (D-TACC/Tacc) and Mini spindles (Msps) correctly to the meiosis II spindles, suggesting that failure to localize these proteins may perturb SAC function. Furthermore, immediately after the establishment of the female pronucleus, D-TACC and Caenorhabditis elegans BicD, tacc and Chc are also needed for pronuclear fusion, suggesting that the underlying mechanism might be more widely used across species.
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Affiliation(s)
| | - Dirk Beuchle
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Gabriella Saro
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Greco Hernández
- Instituto Nacional de Cancerología (INCan) 2 Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer , , 14080-Tlalpan, Mexico City , Mexico
| | - Giovanna Maldonado
- Instituto Nacional de Cancerología (INCan) 2 Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer , , 14080-Tlalpan, Mexico City , Mexico
| | - Dominique Brunßen
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Peter Meister
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Beat Suter
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
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10
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Dynamics of maternal gene expression in Rhodnius prolixus. Sci Rep 2022; 12:6538. [PMID: 35449214 PMCID: PMC9023505 DOI: 10.1038/s41598-022-09874-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 03/14/2022] [Indexed: 11/08/2022] Open
Abstract
The study of developmental processes in Rhodnius prolixus has recently advanced with the sequencing of the genome. In this work, we analyze the maternal gene expression driving oogenesis and early embryogenesis in R. prolixus. We examined the transcriptional profile of mRNAs to establish the genes expressed across the ovary, unfertilized eggs and different embryonic stages of R. prolixus until the formation of the germ band anlage (0, 12, 24, and 48 h post egg laying). We identified 81 putative maternal and ovary-related genes and validated their expression by qRT-PCR. We validate the function of the ortholog gene Bicaudal-D (Rp-BicD) by in situ hybridization and parental RNAi. Consistent with a role in oogenesis and early development of R. prolixus, we show that lack of Rp-BicD does not significantly affect oogenesis but impairs the formation of the blastoderm. Based on our findings, we propose three times of action for maternal genes during oogenesis and embryogenesis in R. prolixus.
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11
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Baker FC, Neiswender H, Veeranan-Karmegam R, Gonsalvez GB. In vivo proximity biotin ligation identifies the interactome of Egalitarian, a Dynein cargo adaptor. Development 2021; 148:273472. [DOI: 10.1242/dev.199935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 10/18/2021] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Numerous motors of the Kinesin family contribute to plus-end-directed microtubule transport. However, almost all transport towards the minus-end of microtubules involves Dynein. Understanding the mechanism by which Dynein transports this vast diversity of cargo is the focus of intense research. In selected cases, adaptors that link a particular cargo with Dynein have been identified. However, the sheer diversity of cargo suggests that additional adaptors must exist. We used the Drosophila egg chamber as a model to address this issue. Within egg chambers, Egalitarian is required for linking mRNA with Dynein. However, in the absence of Egalitarian, Dynein transport into the oocyte is severely compromised. This suggests that additional cargoes might be linked to Dynein in an Egalitarian-dependent manner. We therefore used proximity biotin ligation to define the interactome of Egalitarian. This approach yielded several novel interacting partners, including P body components and proteins that associate with Dynein in mammalian cells. We also devised and validated a nanobody-based proximity biotinylation strategy that can be used to define the interactome of any GFP-tagged protein.
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Affiliation(s)
- Frederick C. Baker
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Hannah Neiswender
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Rajalakshmi Veeranan-Karmegam
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Graydon B. Gonsalvez
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
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12
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Neiswender H, Goldman CH, Veeranan-Karmegam R, Gonsalvez GB. Dynein light chain-dependent dimerization of Egalitarian is essential for maintaining oocyte fate in Drosophila. Dev Biol 2021; 478:76-88. [PMID: 34181915 DOI: 10.1016/j.ydbio.2021.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/02/2021] [Accepted: 06/17/2021] [Indexed: 11/28/2022]
Abstract
Egalitarian (Egl) is an RNA adaptor for the Dynein motor and is thought to link numerous, perhaps hundreds, of mRNAs with Dynein. Dynein, in turn, is responsible for the transport and localization of these mRNAs. Studies have shown that efficient mRNA binding by Egl requires the protein to dimerize. We recently demonstrated that Dynein light chain (Dlc) is responsible for facilitating the dimerization of Egl. Mutations in Egl that fail to interact with Dlc do not dimerize, and as such, are defective for mRNA binding. Consequently, this mutant does not efficiently associate with BicaudalD (BicD), the factor responsible for linking the Egl/mRNA complex with Dynein. In this report, we tested whether artificially dimerizing this Dlc-binding mutant using a leucine zipper would restore mRNA binding and rescue mutant phenotypes in vivo. Interestingly, we found that although artificial dimerization of Egl restored BicD binding, it only partially restored mRNA binding. As a result, Egl-dependent phenotypes, such as oocyte specification and mRNA localization, were only partially rescued. We hypothesize that Dlc-mediated dimerization of Egl results in a three-dimensional conformation of the Egl dimer that is best suited for mRNA binding. Although the leucine zipper restores Egl dimerization, it likely does not enable Egl to assemble into the conformation required for maximal mRNA binding activity.
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Affiliation(s)
- Hannah Neiswender
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA
| | - Chandler H Goldman
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA
| | - Rajalakshmi Veeranan-Karmegam
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA
| | - Graydon B Gonsalvez
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA.
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13
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Goldman CH, Neiswender H, Baker F, Veeranan-Karmegam R, Misra S, Gonsalvez GB. Optimal RNA binding by Egalitarian, a Dynein cargo adaptor, is critical for maintaining oocyte fate in Drosophila. RNA Biol 2021; 18:2376-2389. [PMID: 33904382 DOI: 10.1080/15476286.2021.1914422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The Dynein motor is responsible for the localization of numerous mRNAs within Drosophila oocytes and embryos. The RNA binding protein, Egalitarian (Egl), is thought to link these various RNA cargoes with Dynein. Although numerous studies have shown that Egl is able to specifically associate with these RNAs, the nature of these interactions has remained elusive. Egl contains a central RNA binding domain that shares limited homology with an exonuclease, yet Egl binds to RNA without degrading it. Mutations have been identified within Egl that disrupt its association with its protein interaction partners, BicaudalD (BicD) and Dynein light chain (Dlc), but no mutants have been described that are specifically defective for RNA binding. In this report, we identified a series of positively charged residues within Egl that are required for RNA binding. Using corresponding RNA binding mutants, we demonstrate that specific RNA cargoes are more reliant on maximal Egl RNA biding activity for their correct localization in comparison to others. We also demonstrate that specification and maintenance of oocyte fate requires maximal Egl RNA binding activity. Even a subtle reduction in Egl's RNA binding activity completely disrupts this process. Our results show that efficient RNA localization at the earliest stages of oogenesis is required for specification of the oocyte and restriction of meiosis to a single cell.
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Affiliation(s)
- Chandler H Goldman
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA.,Department of Genetics, Davidson Life Sciences Complex, University of Georgia, Athens, GA, USA
| | - Hannah Neiswender
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Frederick Baker
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | | | - Saurav Misra
- Dept. Of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS,USA
| | - Graydon B Gonsalvez
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
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14
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Abouward R, Schiavo G. Walking the line: mechanisms underlying directional mRNA transport and localisation in neurons and beyond. Cell Mol Life Sci 2021; 78:2665-2681. [PMID: 33341920 PMCID: PMC8004493 DOI: 10.1007/s00018-020-03724-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/02/2020] [Accepted: 11/25/2020] [Indexed: 12/21/2022]
Abstract
Messenger RNA (mRNA) localisation enables a high degree of spatiotemporal control on protein synthesis, which contributes to establishing the asymmetric protein distribution required to set up and maintain cellular polarity. As such, a tight control of mRNA localisation is essential for many biological processes during development and in adulthood, such as body axes determination in Drosophila melanogaster and synaptic plasticity in neurons. The mechanisms controlling how mRNAs are localised, including diffusion and entrapment, local degradation and directed active transport, are largely conserved across evolution and have been under investigation for decades in different biological models. In this review, we will discuss the standing of the field regarding directional mRNA transport in light of the recent discovery that RNA can hitchhike on cytoplasmic organelles, such as endolysosomes, and the impact of these transport modalities on our understanding of neuronal function during development, adulthood and in neurodegeneration.
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Affiliation(s)
- Reem Abouward
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
- The Francis Crick Institute, 1 Midland Rd, London, NW1 1AT, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK.
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15
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Bhagavatula S, Knust E. A putative stem-loop structure in Drosophila crumbs is required for mRNA localisation in epithelia and germline cells. J Cell Sci 2021; 134:224086. [PMID: 33310910 DOI: 10.1242/jcs.236497] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 11/30/2020] [Indexed: 01/02/2023] Open
Abstract
Crumbs (Crb) is an evolutionarily conserved transmembrane protein localised to the apical membrane of epithelial cells. Loss or mislocalisation of Crb is often associated with disruption of apicobasal cell polarity. crb mRNA is also apically enriched in epithelial cells, and, as shown here, accumulates in the oocyte of developing egg chambers. We narrowed down the localisation element (LE) of crb mRNA to 47 nucleotides, which form a putative stem-loop structure that may be recognised by Egalitarian (Egl). Mutations in conserved nucleotides abrogate apical transport. crb mRNA enrichment in the oocyte is affected in egl mutant egg chambers. A CRISPR-based genomic deletion of the crb locus that includes the LE disrupts asymmetric crb mRNA localisation in epithelia and prevents its accumulation in the oocyte during early stages of oogenesis, but does not affect Crb protein localisation in embryonic and follicular epithelia. However, flies lacking the LE show ectopic Crb protein expression in the nurse cells. These data suggest an additional role for the Drosophila 3'-UTR in regulating translation in a tissue-specific manner.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Srija Bhagavatula
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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16
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Liu R, Billington N, Yang Y, Bond C, Hong A, Siththanandan V, Takagi Y, Sellers JR. A binding protein regulates myosin-7a dimerization and actin bundle assembly. Nat Commun 2021; 12:563. [PMID: 33495456 PMCID: PMC7835385 DOI: 10.1038/s41467-020-20864-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 12/07/2020] [Indexed: 01/17/2023] Open
Abstract
Myosin-7a, despite being monomeric in isolation, plays roles in organizing actin-based cell protrusions such as filopodia, microvilli and stereocilia, as well as transporting cargoes within them. Here, we identify a binding protein for Drosophila myosin-7a termed M7BP, and describe how M7BP assembles myosin-7a into a motile complex that enables cargo translocation and actin cytoskeletal remodeling. M7BP binds to the autoinhibitory tail of myosin-7a, extending the molecule and activating its ATPase activity. Single-molecule reconstitution show that M7BP enables robust motility by complexing with myosin-7a as 2:2 translocation dimers in an actin-regulated manner. Meanwhile, M7BP tethers actin, enhancing complex’s processivity and driving actin-filament alignment during processive runs. Finally, we show that myosin-7a-M7BP complex assembles actin bundles and filopodia-like protrusions while migrating along them in living cells. Together, these findings provide insights into the mechanisms by which myosin-7a functions in actin protrusions. Myosin-7a is found in actin bundles, microvilli and stereocilia, and plays conserved roles in hearing and vision. Here the authors identify M7BP, a myosin-7a binding protein that activates and dimerizes myosin-7a, enabling cargo transport and assembly of actin bundles and filopodia-like protrusions
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Affiliation(s)
- Rong Liu
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Neil Billington
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yi Yang
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.,Laboratory of Functional Proteomics, College of Veterinary Medicine, Hunan Agricultural University, 410128, Changsha, Hunan, China
| | - Charles Bond
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Amy Hong
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Verl Siththanandan
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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17
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Koboldt DC, Waldrop MA, Wilson RK, Flanigan KM. The Genotypic and Phenotypic Spectrum of
BICD2
Variants in Spinal Muscular Atrophy. Ann Neurol 2020; 87:487-496. [DOI: 10.1002/ana.25704] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/12/2020] [Accepted: 02/12/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Daniel C. Koboldt
- Institute for Genomic Medicine Nationwide Children's Hospital Columbus OH
- Department of Pediatrics Ohio State University Columbus OH
| | - Megan A. Waldrop
- Department of Pediatrics Ohio State University Columbus OH
- Center for Gene Therapy Nationwide Children's Hospital Columbus OH
- Department of Neurology Ohio State University Columbus OH
| | - Richard K. Wilson
- Institute for Genomic Medicine Nationwide Children's Hospital Columbus OH
- Department of Pediatrics Ohio State University Columbus OH
| | - Kevin M. Flanigan
- Department of Pediatrics Ohio State University Columbus OH
- Center for Gene Therapy Nationwide Children's Hospital Columbus OH
- Department of Neurology Ohio State University Columbus OH
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18
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Barr J, Gilmutdinov R, Wang L, Shidlovskii Y, Schedl P. The Drosophila CPEB Protein Orb Specifies Oocyte Fate by a 3'UTR-Dependent Autoregulatory Loop. Genetics 2019; 213:1431-1446. [PMID: 31594794 PMCID: PMC6893371 DOI: 10.1534/genetics.119.302687] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 09/26/2019] [Indexed: 11/18/2022] Open
Abstract
orb encodes one of the two fly CPEB proteins. These widely conserved proteins bind to the 3'UTRs of target messenger RNAs (mRNAs) and activate or repress their translation. We show here that a positive autoregulatory loop driven by the orb gene propels the specification of oocyte identity in Drosophila egg chambers. Oocyte fate specification is mediated by a 3'UTR-dependent mechanism that concentrates orb mRNAs and proteins in one of the two pro-oocytes in the 16-cell germline cyst. When the orb 3'UTR is deleted, orb mRNA and protein fail to localize and all 16 cells become nurse cells. In wild type, the oocyte is specified when orb and other gene products concentrate in a single cell in region 2b of the germarium. A partially functional orb 3'UTR replacement delays oocyte specification until the egg chambers reach stage 2 of oogenesis. Before this point, orb mRNA and protein are unlocalized, as are other markers of oocyte identity, and the oocyte is not specified. After stage 2, ∼50% of the chambers successfully localize orb in a single cell, and this cell assumes oocyte identity. In the remaining chambers, the orb autoregulatory loop is not activated and no oocyte is formed. Finally, maintenance of oocyte identity requires continuous orb activity.
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Affiliation(s)
- Justinn Barr
- Department of Molecular Biology, Princeton University, New Jersey 08540
| | - Rudolf Gilmutdinov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow 119334, Russia
| | - Linus Wang
- Department of Molecular Biology, Princeton University, New Jersey 08540
| | - Yulii Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow 119334, Russia
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, New Jersey 08540
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow 119334, Russia
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19
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Goldman CH, Neiswender H, Veeranan-Karmegam R, Gonsalvez GB. The Egalitarian binding partners Dynein light chain and Bicaudal-D act sequentially to link mRNA to the Dynein motor. Development 2019; 146:dev.176529. [PMID: 31391195 DOI: 10.1242/dev.176529] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 07/15/2019] [Indexed: 01/24/2023]
Abstract
A conserved mechanism of polarity establishment is the localization of mRNA to specific cellular regions. Although it is clear that many mRNAs are transported along microtubules, much less is known about the mechanism by which these mRNAs are linked to microtubule motors. The RNA binding protein Egalitarian (Egl) is necessary for localization of several mRNAs in Drosophila oocytes and embryos. Egl also interacts with Dynein light chain (Dlc) and Bicaudal-D (BicD). The role of Dlc and BicD in mRNA localization has remained elusive. Both proteins are required for oocyte specification, as is Egl. Null alleles in these genes result in an oogenesis block. In this report, we used an shRNA-depletion strategy to overcome the oogenesis block. Our findings reveal that the primary function of Dlc is to promote Egl dimerization. Loss of dimerization compromises the ability of Egl to bind RNA. Consequently, Egl is not bound to cargo, and is not able to efficiently associate with BicD and the Dynein motor. Our results therefore identify the key molecular steps required for assembling a localization-competent mRNP.
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Affiliation(s)
- Chandler H Goldman
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1459 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Hannah Neiswender
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1459 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Rajalakshmi Veeranan-Karmegam
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1459 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Graydon B Gonsalvez
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1459 Laney Walker Blvd, Augusta, GA 30912, USA
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20
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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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21
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Koboldt DC, Kastury RD, Waldrop MA, Kelly BJ, Mosher TM, McLaughlin H, Corsmeier D, Slaughter JL, Flanigan KM, McBride KL, Mehta L, Wilson RK, White P. In-frame de novo mutation in BICD2 in two patients with muscular atrophy and arthrogryposis. Cold Spring Harb Mol Case Stud 2018; 4:mcs.a003160. [PMID: 30054298 PMCID: PMC6169820 DOI: 10.1101/mcs.a003160] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/23/2018] [Indexed: 01/10/2023] Open
Abstract
We describe two unrelated patients, a 12-yr-old female and a 6-yr-old male, with congenital contractures and severe congenital muscular atrophy. Exome and genome sequencing of the probands and their unaffected parents revealed that they have the same de novo deletion in BICD2 (c.1636_1638delAAT). The variant, which has never been reported, results in an in-frame 3-bp deletion and is predicted to cause loss of an evolutionarily conserved asparagine residue at position 546 in the protein. Missense mutations in BICD2 cause autosomal dominant spinal muscular atrophy, lower-extremity predominant 2 (SMALED2), a disease characterized by muscle weakness and arthrogryposis of early onset and slow progression. The p.Asn546del clusters with four pathogenic missense variants in a region that likely binds molecular motor KIF5A. Protein modeling suggests that removing the highly conserved asparagine residue alters BICD2 protein structure. Our findings support a broader phenotypic spectrum of BICD2 mutations that may include severe manifestations such as cerebral atrophy, seizures, dysmorphic facial features, and profound muscular atrophy.
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Affiliation(s)
- Daniel C Koboldt
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Rama D Kastury
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Megan A Waldrop
- Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA.,Center for Gene Therapy, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Benjamin J Kelly
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Theresa Mihalic Mosher
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA.,Division of Genetic and Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | | | - Don Corsmeier
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Jonathan L Slaughter
- Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA.,Center for Perinatal Research and Division of Neonatology, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Kevin M Flanigan
- Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA.,Center for Gene Therapy, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Neurology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Kim L McBride
- Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA.,Division of Genetic and Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Lakshmi Mehta
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA.,Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Richard K Wilson
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Peter White
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
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22
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Suter B. RNA localization and transport. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:938-951. [PMID: 30496039 DOI: 10.1016/j.bbagrm.2018.08.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/23/2018] [Accepted: 08/23/2018] [Indexed: 12/30/2022]
Abstract
RNA localization serves numerous purposes from controlling development and differentiation to supporting the physiological activities of cells and organisms. After a brief introduction into the history of the study of mRNA localization I will focus on animal systems, describing in which cellular compartments and in which cell types mRNA localization was observed and studied. In recent years numerous novel localization patterns have been described, and countless mRNAs have been documented to accumulate in specific subcellular compartments. These fascinating revelations prompted speculations about the purpose of localizing all these mRNAs. In recent years experimental evidence for an unexpected variety of different functions has started to emerge. Aside from focusing on the functional aspects, I will discuss various ways of localizing mRNAs with a focus on the mechanism of active and directed transport on cytoskeletal tracks. Structural studies combined with imaging of transport and biochemical studies have contributed to the enormous recent progress, particularly in understanding how dynein/dynactin/BicD (DDB) dependent transport on microtubules works. This transport process actively localizes diverse cargo in similar ways to the minus end of microtubules and, at least in flies, also individual mRNA molecules. A sophisticated mechanism ensures that cargo loading licenses processive transport.
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Affiliation(s)
- Beat Suter
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland.
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23
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Perez-Pepe M, Fernández-Alvarez AJ, Boccaccio GL. Life and Work of Stress Granules and Processing Bodies: New Insights into Their Formation and Function. Biochemistry 2018; 57:2488-2498. [PMID: 29595960 DOI: 10.1021/acs.biochem.8b00025] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The dynamic formation of stress granules (SGs), processing bodies (PBs), and related RNA organelles regulates diverse cellular processes, including the coordination of functionally connected messengers, the translational regulation at the synapse, and the control of viruses and retrotransposons. Recent studies have shown that pyruvate kinase and other enzymes localize in SGs and PBs, where they become protected from stress insults. These observations may have implications for enzyme regulation and metabolic control exerted by RNA-based organelles. The formation of these cellular bodies is governed by liquid-liquid phase separation (LLPS) processes, and it needs to be strictly controlled to prevent pathogenic aggregation. The intracellular concentration of key metabolites, such as ATP and sterol derivatives, may influence protein solubility, thus affecting the dynamics of liquid organelles. LLPS in vitro depends on the thermal diffusion of macromolecules, which is limited inside cells, where the condensation and dissolution of membrane-less organelles are helped by energy-driven processes. The active transport by the retrograde motor dynein helps SG assembly, whereas the anterograde motor kinesin mediates SG dissolution; a tug of war between these two molecular motors allows transient SG formation. There is evidence that the efficiency of dynein-mediated transport increases with the number of motor molecules associated with the cargo. The dynein-dependent transport may be influenced by cargo size as larger cargos can load a larger number of motors. We propose a model based on this emergent property of dynein motors, which would be collectively stronger during SG condensation and weaker during SG breakdown, thus allowing kinesin-mediated dispersion.
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Affiliation(s)
- Marcelo Perez-Pepe
- Instituto Leloir and Instituto de Investigaciones Bioquı́micas de Buenos Aires (IIBBA)-CONICET , Buenos Aires , Argentina
| | - Ana J Fernández-Alvarez
- Instituto Leloir and Instituto de Investigaciones Bioquı́micas de Buenos Aires (IIBBA)-CONICET , Buenos Aires , Argentina
| | - Graciela L Boccaccio
- Instituto Leloir and Instituto de Investigaciones Bioquı́micas de Buenos Aires (IIBBA)-CONICET , Buenos Aires , Argentina
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24
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Abstract
Asymmetric localization of mRNAs is a widespread gene regulatory mechanism that is crucial for many cellular processes. The localization of a transcript involves multiple steps and requires several protein factors to mediate transport, anchoring and translational repression of the mRNA. Specific recognition of the localizing transcript is a key step that depends on linear or structured localization signals, which are bound by RNA-binding proteins. Genetic studies have identified many components involved in mRNA localization. However, mechanistic aspects of the pathway are still poorly understood. Here we provide an overview of structural studies that contributed to our understanding of the mechanisms underlying mRNA localization, highlighting open questions and future challenges.
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Affiliation(s)
| | - Fulvia Bono
- a Max Planck Institute for Developmental Biology , Tübingen , Germany
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