1
|
Siddiqui NU, Karaiskakis A, Goldman AL, Eagle WVI, Low TCH, Luo H, Smibert CA, Gavis ER, Lipshitz HD. Smaug regulates germ plasm assembly and primordial germ cell number in Drosophila embryos. SCIENCE ADVANCES 2024; 10:eadg7894. [PMID: 38608012 PMCID: PMC11014450 DOI: 10.1126/sciadv.adg7894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 03/12/2024] [Indexed: 04/14/2024]
Abstract
During Drosophila oogenesis, the Oskar (OSK) RNA binding protein (RBP) determines the amount of germ plasm that assembles at the posterior pole of the oocyte. Here, we identify mechanisms that subsequently regulate germ plasm assembly in the early embryo. We show that the Smaug (SMG) RBP is transported into the germ plasm of the early embryo where it accumulates in the germ granules. SMG binds to and represses translation of the osk messenger RNA (mRNA) as well as the bruno 1 (bru1) mRNA, which encodes an RBP that we show promotes germ plasm production. Loss of SMG or mutation of SMG's binding sites in the osk or bru1 mRNA results in excess translation of these transcripts in the germ plasm, accumulation of excess germ plasm, and budding of excess primordial germ cells (PGCs). Therefore, SMG triggers a posttranscriptional regulatory pathway that attenuates the amount of germ plasm in embryos to modulate the number of PGCs.
Collapse
Affiliation(s)
- Najeeb U. Siddiqui
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
- Program in Developmental and Stem Cell Biology, Research Institute, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Angelo Karaiskakis
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Aaron L. Goldman
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
- Program in Developmental and Stem Cell Biology, Research Institute, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Whitby V. I. Eagle
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Timothy C. H. Low
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Hua Luo
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Craig A. Smibert
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
- Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Elizabeth R. Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Howard D. Lipshitz
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| |
Collapse
|
2
|
Brockett JS, Manalo T, Zein-Sabatto H, Lee J, Fang J, Chu P, Feng H, Patil D, Davidson P, Ogan K, Master VA, Pattaras JG, Roberts DL, Bergquist SH, Reyna MA, Petros JA, Lerit DA, Arnold RS. A missense SNP in the tumor suppressor SETD2 reduces H3K36me3 and mitotic spindle integrity in Drosophila. Genetics 2024; 226:iyae015. [PMID: 38290049 PMCID: PMC10990431 DOI: 10.1093/genetics/iyae015] [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: 09/08/2023] [Revised: 01/11/2024] [Accepted: 01/11/2024] [Indexed: 02/01/2024] Open
Abstract
Mutations in SETD2 are among the most prevalent drivers of renal cell carcinoma (RCC). We identified a novel single nucleotide polymorphism (SNP) in SETD2, E902Q, within a subset of RCC patients, which manifests as both an inherited or tumor-associated somatic mutation. To determine if the SNP is biologically functional, we used CRISPR-based genome editing to generate the orthologous mutation within the Drosophila melanogaster Set2 gene. In Drosophila, the homologous amino acid substitution, E741Q, reduces H3K36me3 levels comparable to Set2 knockdown, and this loss is rescued by reintroduction of a wild-type Set2 transgene. We similarly uncovered significant defects in spindle morphogenesis, consistent with the established role of SETD2 in methylating α-Tubulin during mitosis to regulate microtubule dynamics and maintain genome stability. These data indicate the Set2 E741Q SNP affects both histone methylation and spindle integrity. Moreover, this work further suggests the SETD2 E902Q SNP may hold clinical relevance.
Collapse
Affiliation(s)
- Jovan S Brockett
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Tad Manalo
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Hala Zein-Sabatto
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jina Lee
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Junnan Fang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Philip Chu
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Harry Feng
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Dattatraya Patil
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Priscilla Davidson
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Kenneth Ogan
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Viraj A Master
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - John G Pattaras
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David L Roberts
- Emory University Department of Medicine, Division of General Internal Medicine, Atlanta, GA 30322, USA
| | - Sharon H Bergquist
- Emory University Department of Medicine, Division of General Internal Medicine, Atlanta, GA 30322, USA
| | - Matthew A Reyna
- Department of Biomedical Informatics, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - John A Petros
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Rebecca S Arnold
- Department of Urology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| |
Collapse
|
3
|
Ridwan SM, Twillie A, Poursaeid S, Beard EK, Bener MB, Antel M, Cowan AE, Matsuda S, Inaba M. Diffusible fraction of niche BMP ligand safeguards stem-cell differentiation. Nat Commun 2024; 15:1166. [PMID: 38326318 PMCID: PMC10850516 DOI: 10.1038/s41467-024-45408-7] [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: 03/01/2023] [Accepted: 01/22/2024] [Indexed: 02/09/2024] Open
Abstract
Drosophila male germline stem cells (GSCs) reside at the tip of the testis and surround a cluster of niche cells. Decapentaplegic (Dpp) is one of the well-established ligands and has a major role in maintaining stem cells located in close proximity. However, the existence and the role of the diffusible fraction of Dpp outside of the niche have been unclear. Here, using genetically-encoded nanobodies called Morphotraps, we physically block Dpp diffusion without interfering with niche-stem cell signaling and find that a diffusible fraction of Dpp is required to ensure differentiation of GSC daughter cells, opposite of its role in maintenance of GSC in the niche. Our work provides an example in which a soluble niche ligand induces opposed cellular responses in stem cells versus in differentiating descendants to ensure spatial control of the niche. This may be a common mechanism to regulate tissue homeostasis.
Collapse
Affiliation(s)
- Sharif M Ridwan
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Autumn Twillie
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Samaneh Poursaeid
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Emma Kristine Beard
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Muhammed Burak Bener
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Matthew Antel
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Ann E Cowan
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT, USA
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
| | - Shinya Matsuda
- Biozentrum, University of Basel, Basel, Switzerland.
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
| | - Mayu Inaba
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA.
| |
Collapse
|
4
|
Tam R, Harris TJC. Reshaping the Syncytial Drosophila Embryo with Cortical Actin Networks: Four Main Steps of Early Development. Results Probl Cell Differ 2024; 71:67-90. [PMID: 37996673 DOI: 10.1007/978-3-031-37936-9_4] [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] [Indexed: 11/25/2023]
Abstract
Drosophila development begins as a syncytium. The large size of the one-cell embryo makes it ideal for studying the structure, regulation, and effects of the cortical actin cytoskeleton. We review four main steps of early development that depend on the actin cortex. At each step, dynamic remodelling of the cortex has specific effects on nuclei within the syncytium. During axial expansion, a cortical actomyosin network assembles and disassembles with the cell cycle, generating cytoplasmic flows that evenly distribute nuclei along the ovoid cell. When nuclei move to the cell periphery, they seed Arp2/3-based actin caps which grow into an array of dome-like compartments that house the nuclei as they divide at the cell cortex. To separate germline nuclei from the soma, posterior germ plasm induces full cleavage of mono-nucleated primordial germ cells from the syncytium. Finally, zygotic gene expression triggers formation of the blastoderm epithelium via cellularization and simultaneous division of ~6000 mono-nucleated cells from a single internal yolk cell. During these steps, the cortex is regulated in space and time, gains domain and sub-domain structure, and undergoes mesoscale interactions that lay a structural foundation of animal development.
Collapse
Affiliation(s)
- Rebecca Tam
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada.
| |
Collapse
|
5
|
Curnutte HA, Lan X, Sargen M, Ao Ieong SM, Campbell D, Kim H, Liao Y, Lazar SB, Trcek T. Proteins rather than mRNAs regulate nucleation and persistence of Oskar germ granules in Drosophila. Cell Rep 2023; 42:112723. [PMID: 37384531 PMCID: PMC10439980 DOI: 10.1016/j.celrep.2023.112723] [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: 12/09/2022] [Revised: 04/24/2023] [Accepted: 06/13/2023] [Indexed: 07/01/2023] Open
Abstract
RNA granules are membraneless condensates that provide functional compartmentalization within cells. The mechanisms by which RNA granules form are under intense investigation. Here, we characterize the role of mRNAs and proteins in the formation of germ granules in Drosophila. Super-resolution microscopy reveals that the number, size, and distribution of germ granules is precisely controlled. Surprisingly, germ granule mRNAs are not required for the nucleation or the persistence of germ granules but instead control their size and composition. Using an RNAi screen, we determine that RNA regulators, helicases, and mitochondrial proteins regulate germ granule number and size, while the proteins of the endoplasmic reticulum, nuclear pore complex, and cytoskeleton control their distribution. Therefore, the protein-driven formation of Drosophila germ granules is mechanistically distinct from the RNA-dependent condensation observed for other RNA granules such as stress granules and P-bodies.
Collapse
Affiliation(s)
- Harrison A Curnutte
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Xinyue Lan
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Manuel Sargen
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Si Man Ao Ieong
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Dylan Campbell
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Hyosik Kim
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Yijun Liao
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Sarah Bailah Lazar
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Tatjana Trcek
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
| |
Collapse
|
6
|
Chen P, Aravin AA. Genetic control of a sex-specific piRNA program. Curr Biol 2023; 33:1825-1835.e3. [PMID: 37059098 PMCID: PMC10431932 DOI: 10.1016/j.cub.2023.03.057] [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: 11/17/2022] [Revised: 02/15/2023] [Accepted: 03/17/2023] [Indexed: 04/16/2023]
Abstract
Sexually dimorphic traits in morphologies are widely studied,1,2,3,4 but those in essential molecular pathways remain largely unexplored. Previous work showed substantial sex differences in Drosophila gonadal piRNAs,5 which guide PIWI proteins to silence selfish genetic elements, thereby safeguarding fertility.6,7,8 However, the genetic control mechanisms of piRNA sexual dimorphism remain unknown. Here, we showed that most sex differences in the piRNA program originate from the germ line rather than the gonadal somatic cells. Building on this, we dissected the contribution of sex chromosomes and cellular sexual identity toward the sex-specific germline piRNA program. We found that the presence of the Y chromosome is sufficient to recapitulate some aspects of the male piRNA program in a female cellular environment. Meanwhile, sexual identity controls the sexually divergent piRNA production from X-linked and autosomal loci, revealing a crucial input from sex determination into piRNA biogenesis. Sexual identity regulates piRNA biogenesis through Sxl, and this effect is mediated, in part, through chromatin proteins Phf7 and Kipferl. Together, our work delineated the genetic control of a sex-specific piRNA program, where sex chromosomes and sexual identity collectively sculpt an essential molecular trait.
Collapse
Affiliation(s)
- Peiwei Chen
- California Institute of Technology, Division of Biology and Biological Engineering, Pasadena, CA 91125, USA.
| | - Alexei A Aravin
- California Institute of Technology, Division of Biology and Biological Engineering, Pasadena, CA 91125, USA.
| |
Collapse
|
7
|
Hakes AC, Gavis ER. Plasticity of Drosophila germ granules during germ cell development. PLoS Biol 2023; 21:e3002069. [PMID: 37053289 PMCID: PMC10128949 DOI: 10.1371/journal.pbio.3002069] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 04/25/2023] [Accepted: 03/07/2023] [Indexed: 04/15/2023] Open
Abstract
Compartmentalization of RNAs and proteins into membraneless structures called granules is a ubiquitous mechanism for organizing and regulating cohorts of RNAs. Germ granules are ribonucleoprotein (RNP) assemblies required for germline development across the animal kingdom, but their regulatory roles in germ cells are not fully understood. We show that after germ cell specification, Drosophila germ granules enlarge through fusion and this growth is accompanied by a shift in function. Whereas germ granules initially protect their constituent mRNAs from degradation, they subsequently target a subset of these mRNAs for degradation while maintaining protection of others. This functional shift occurs through the recruitment of decapping and degradation factors to the germ granules, which is promoted by decapping activators and renders these structures P body-like. Disrupting either the mRNA protection or degradation function results in germ cell migration defects. Our findings reveal plasticity in germ granule function that allows them to be repurposed at different stages of development to ensure population of the gonad by germ cells. Additionally, these results reveal an unexpected level of functional complexity whereby constituent RNAs within the same granule type can be differentially regulated.
Collapse
Affiliation(s)
- Anna C Hakes
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| |
Collapse
|
8
|
Siddiqui NU, Karaiskakis A, Goldman AL, Eagle WV, Smibert CA, Gavis ER, Lipshitz HD. Smaug regulates germ plasm synthesis and primordial germ cell number in Drosophila embryos by repressing the oskar and bruno 1 mRNAs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.27.530189. [PMID: 36909513 PMCID: PMC10002672 DOI: 10.1101/2023.02.27.530189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
During Drosophila oogenesis, the Oskar (OSK) RNA-binding protein (RBP) determines the amount of germ plasm that assembles at the posterior pole of the oocyte. Here we identify the mechanisms that regulate the osk mRNA in the early embryo. We show that the Smaug (SMG) RBP is transported into the germ plasm of the early embryo where it accumulates in the germ granules. SMG binds to and represses translation of the osk mRNA itself as well as the bruno 1 (bru1) mRNA, which encodes an RBP that we show promotes germ plasm production. Loss of SMG or mutation of SMG's binding sites in the osk or bru1 mRNAs results in ectopic translation of these transcripts in the germ plasm and excess PGCs. SMG therefore triggers a post-transcriptional regulatory pathway that attenuates germ plasm synthesis in embryos, thus modulating the number of PGCs.
Collapse
Affiliation(s)
- Najeeb U. Siddiqui
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario, Canada M5G 1M1
- Program in Developmental & Stem Cell Biology, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Angelo Karaiskakis
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario, Canada M5G 1M1
| | - Aaron L. Goldman
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario, Canada M5G 1M1
- Program in Developmental & Stem Cell Biology, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Whitby V.I. Eagle
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA
| | - Craig A. Smibert
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario, Canada M5G 1M1
- Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, Ontario, Canada M5G 1M1
| | - Elizabeth R. Gavis
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA
| | - Howard D. Lipshitz
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario, Canada M5G 1M1
| |
Collapse
|
9
|
Colonnetta MM, Schedl P, Deshpande G. Germline/soma distinction in Drosophila embryos requires regulators of zygotic genome activation. eLife 2023; 12:78188. [PMID: 36598809 PMCID: PMC9812407 DOI: 10.7554/elife.78188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 12/23/2022] [Indexed: 01/05/2023] Open
Abstract
In Drosophila melanogaster embryos, somatic versus germline identity is the first cell fate decision. Zygotic genome activation (ZGA) orchestrates regionalized gene expression, imparting specific identity on somatic cells. ZGA begins with a minor wave that commences at nuclear cycle (NC)8 under the guidance of chromatin accessibility factors (Zelda, CLAMP, GAF), followed by the major wave during NC14. By contrast, primordial germ cell (PGC) specification requires maternally deposited and posteriorly anchored germline determinants. This is accomplished by a centrosome coordinated release and sequestration of germ plasm during the precocious cellularization of PGCs in NC10. Here, we report a novel requirement for Zelda and CLAMP during the establishment of the germline/soma distinction. When their activity is compromised, PGC determinants are not properly sequestered, and specification is disrupted. Conversely, the spreading of PGC determinants from the posterior pole adversely influences transcription in the neighboring somatic nuclei. These reciprocal aberrations can be correlated with defects in centrosome duplication/separation that are known to induce inappropriate transmission of the germ plasm. Interestingly, consistent with the ability of bone morphogenetic protein (BMP) signaling to influence specification of embryonic PGCs, reduction in the transcript levels of a BMP family ligand, decapentaplegic (dpp), is exacerbated at the posterior pole.
Collapse
Affiliation(s)
- Megan M Colonnetta
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Paul Schedl
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Girish Deshpande
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| |
Collapse
|
10
|
Chiappetta A, Liao J, Tian S, Trcek T. Structural and functional organization of germ plasm condensates. Biochem J 2022; 479:2477-2495. [PMID: 36534469 PMCID: PMC10722471 DOI: 10.1042/bcj20210815] [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: 09/09/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 12/23/2022]
Abstract
Reproductive success of metazoans relies on germ cells. These cells develop early during embryogenesis, divide and undergo meiosis in the adult to make sperm and oocytes. Unlike somatic cells, germ cells are immortal and transfer their genetic material to new generations. They are also totipotent, as they differentiate into different somatic cell types. The maintenance of immortality and totipotency of germ cells depends on extensive post-transcriptional and post-translational regulation coupled with epigenetic remodeling, processes that begin with the onset of embryogenesis [1, 2]. At the heart of this regulation lie germ granules, membraneless ribonucleoprotein condensates that are specific to the germline cytoplasm called the germ plasm. They are a hallmark of all germ cells and contain several proteins and RNAs that are conserved across species. Interestingly, germ granules are often structured and tend to change through development. In this review, we describe how the structure of germ granules becomes established and discuss possible functional outcomes these structures have during development.
Collapse
|
11
|
Lerit DA. Reflections on mentorship as an early career researcher. Mol Biol Cell 2022; 33:ae3. [PMID: 36399627 PMCID: PMC9727808 DOI: 10.1091/mbc.e22-08-0359] [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] [Indexed: 11/19/2022] Open
Abstract
It is my great honor to receive the 2022 Günter Blobel Early Career Award from the American Society for Cell Biology. Reflecting upon my research and career trajectory, I recognize the incredible support of my mentors and the hard work of everyone within my lab. I have always relied on a network of advisors and colleagues who supported me throughout my scientific journey. To better support my own trainees, I endeavor to pass on lessons learned while continuously developing and strengthening my own leadership potential. I am a relentless advocate for the success of my trainees, a legacy I pass on from my own mentors.
Collapse
Affiliation(s)
- Dorothy A. Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322,Winship Cancer Institute, Emory University, Atlanta, GA 30322,*Address correspondence to: Dorothy A. Lerit ()
| |
Collapse
|
12
|
Colonnetta MM, Goyal Y, Johnson HE, Syal S, Schedl P, Deshpande G. Preformation and epigenesis converge to specify primordial germ cell fate in the early Drosophila embryo. PLoS Genet 2022; 18:e1010002. [PMID: 34986144 PMCID: PMC8765614 DOI: 10.1371/journal.pgen.1010002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 01/18/2022] [Accepted: 12/17/2021] [Indexed: 11/24/2022] Open
Abstract
A critical step in animal development is the specification of primordial germ cells (PGCs), the precursors of the germline. Two seemingly mutually exclusive mechanisms are implemented across the animal kingdom: epigenesis and preformation. In epigenesis, PGC specification is non-autonomous and depends on extrinsic signaling pathways. The BMP pathway provides the key PGC specification signals in mammals. Preformation is autonomous and mediated by determinants localized within PGCs. In Drosophila, a classic example of preformation, constituents of the germ plasm localized at the embryonic posterior are thought to be both necessary and sufficient for proper determination of PGCs. Contrary to this longstanding model, here we show that these localized determinants are insufficient by themselves to direct PGC specification in blastoderm stage embryos. Instead, we find that the BMP signaling pathway is required at multiple steps during the specification process and functions in conjunction with components of the germ plasm to orchestrate PGC fate. Proper specification of primordial germ cells (PGCs) is crucial as PGCs serve as the precursors of germline stem cells. To specify PGC fate, invertebrates rely upon cell autonomous preformation involving maternally deposited germ plasm. In Drosophila melanogaster, to insulate newly formed PGCs from the adverse effects of the cell-cell signaling pathways, germ plasm determinants silence transcription and attenuate the cell cycle. However, our data on the BMP signaling pathway challenge this long-held view of PGC specification and suggest that appropriate specification of embryonic PGCs is sensitive to the BMP ligand, decapentaplegic (dpp), and its cognate receptor, thickveins. We find that PGCs are not only capable of responding to BMP signals from the soma, but also that these signals impact the proper determination of the germ cells. Based on these unanticipated similarities between mammals and flies, we propose a model integrating contribution of both the cell-autonomous (preformation) and non-autonomous (epigenesis) pathways during PGC determination. Consistent with the model, we have observed dominant genetic interactions between, oskar, the maternal determinant of PGC fate, and the BMP pathway ligand dpp.
Collapse
Affiliation(s)
- Megan M. Colonnetta
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Yogesh Goyal
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Heath E. Johnson
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Sapna Syal
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
| |
Collapse
|
13
|
Zein-Sabatto H, Lerit DA. The Identification and Functional Analysis of mRNA Localizing to Centrosomes. Front Cell Dev Biol 2021; 9:782802. [PMID: 34805187 PMCID: PMC8595238 DOI: 10.3389/fcell.2021.782802] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 10/21/2021] [Indexed: 11/13/2022] Open
Abstract
Centrosomes are multifunctional organelles tasked with organizing the microtubule cytoskeleton required for genome stability, intracellular trafficking, and ciliogenesis. Contributing to the diversity of centrosome functions are cell cycle-dependent oscillations in protein localization and post-translational modifications. Less understood is the role of centrosome-localized messenger RNA (mRNA). Since its discovery, the concept of nucleic acids at the centrosome was controversial, and physiological roles for centrosomal mRNAs remained muddled and underexplored. Over the past decades, however, transcripts, RNA-binding proteins, and ribosomes were detected at the centrosome in various organisms and cell types, hinting at a conservation of function. Indeed, recent work defines centrosomes as sites of local protein synthesis, and defined mRNAs were recently implicated in regulating centrosome functions. In this review, we summarize the evidence for the presence of mRNA at the centrosome and the current work that aims to unravel the biological functions of mRNA localized to centrosomes.
Collapse
Affiliation(s)
| | - Dorothy A. Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| |
Collapse
|
14
|
Hawdon A, Aberkane A, Zenker J. Microtubule-dependent subcellular organisation of pluripotent cells. Development 2021; 148:272646. [PMID: 34710215 DOI: 10.1242/dev.199909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
With the advancement of cutting-edge live imaging technologies, microtubule remodelling has evolved as an integral regulator for the establishment of distinct differentiated cells. However, despite their fundamental role in cell structure and function, microtubules have received less attention when unravelling the regulatory circuitry of pluripotency. Here, we summarise the role of microtubule organisation and microtubule-dependent events required for the formation of pluripotent cells in vivo by deciphering the process of early embryogenesis: from fertilisation to blastocyst. Furthermore, we highlight current advances in elucidating the significance of specific microtubule arrays in in vitro culture systems of pluripotent stem cells and how the microtubule cytoskeleton serves as a highway for the precise intracellular movement of organelles. This Review provides an informed understanding of the intrinsic role of subcellular architecture of pluripotent cells and accentuates their regenerative potential in combination with innovative light-inducible microtubule techniques.
Collapse
Affiliation(s)
- Azelle Hawdon
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Asma Aberkane
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Jennifer Zenker
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia
| |
Collapse
|
15
|
Bergalet J, Patel D, Legendre F, Lapointe C, Benoit Bouvrette LP, Chin A, Blanchette M, Kwon E, Lécuyer E. Inter-dependent Centrosomal Co-localization of the cen and ik2 cis-Natural Antisense mRNAs in Drosophila. Cell Rep 2021; 30:3339-3352.e6. [PMID: 32160541 DOI: 10.1016/j.celrep.2020.02.047] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 12/24/2019] [Accepted: 02/10/2020] [Indexed: 11/30/2022] Open
Abstract
Overlapping genes are prevalent in most genomes, but the extent to which this organization influences regulatory events operating at the post-transcriptional level remains unclear. Studying the cen and ik2 genes of Drosophila melanogaster, which are convergently transcribed as cis-natural antisense transcripts (cis-NATs) with overlapping 3' UTRs, we found that their encoded mRNAs strikingly co-localize to centrosomes. These transcripts physically interact in a 3' UTR-dependent manner, and the targeting of ik2 requires its 3' UTR sequence and the presence of cen mRNA, which serves as the main driver of centrosomal co-localization. The cen transcript undergoes localized translation in proximity to centrosomes, and its localization is perturbed by polysome-disrupting drugs. By interrogating global fractionation-sequencing datasets generated from Drosophila and human cellular models, we find that RNAs expressed as cis-NATs tend to co-localize to specific subcellular fractions. This work suggests that post-transcriptional interactions between RNAs with complementary sequences can dictate their localization fate in the cytoplasm.
Collapse
Affiliation(s)
- Julie Bergalet
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Dhara Patel
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Félix Legendre
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Catherine Lapointe
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Louis Philip Benoit Bouvrette
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Ashley Chin
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | | | - Eunjeong Kwon
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Eric Lécuyer
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada; Division of Experimental Medicine, McGill University, Montréal, QC, Canada.
| |
Collapse
|
16
|
Mukherjee N, Mukherjee C. Germ cell ribonucleoprotein granules in different clades of life: From insects to mammals. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1642. [PMID: 33555143 DOI: 10.1002/wrna.1642] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 12/12/2022]
Abstract
Ribonucleoprotein (RNP) granules are no newcomers in biology. Found in all life forms, ranging across taxa, these membrane-less "organelles" have been classified into different categories based on their composition, structure, behavior, function, and localization. Broadly, they can be listed as stress granules (SGs), processing bodies (PBs), neuronal granules (NGs), and germ cell granules (GCGs). Keeping in line with the topic of this review, RNP granules present in the germ cells have been implicated in a wide range of cellular functions including cellular specification, differentiation, proliferation, and so forth. The mechanisms used by them can be diverse and many of them remain partly obscure and active areas of research. GCGs can be of different types in different organisms and at different stages of development, with multiple types coexisting in the same cell. In this review, the different known subcategories of GCGs have been studied with respect to five distinct model organisms, namely, Drosophila, Caenorhabditis elegans, Xenopus, Zebrafish, and mammals. Of them, the cytoplasmic polar granules in Drosophila, P granules in C. elegans, balbiani body in Xenopus and Zebrafish, and chromatoid bodies in mammals have been specifically emphasized upon. A descriptive account of the same has been provided along with insights into our current understanding of their functional significance with respect to cellular events relating to different developmental and reproductive processes. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Export and Localization > RNA Localization RNA in Disease and Development > RNA in Disease.
Collapse
|
17
|
Colonnetta MM, Lym LR, Wilkins L, Kappes G, Castro EA, Ryder PV, Schedl P, Lerit DA, Deshpande G. Antagonism between germ cell-less and Torso receptor regulates transcriptional quiescence underlying germline/soma distinction. eLife 2021; 10:54346. [PMID: 33459591 PMCID: PMC7843132 DOI: 10.7554/elife.54346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 01/15/2021] [Indexed: 11/13/2022] Open
Abstract
Transcriptional quiescence, an evolutionarily conserved trait, distinguishes the embryonic primordial germ cells (PGCs) from their somatic neighbors. In Drosophila melanogaster, PGCs from embryos maternally compromised for germ cell-less (gcl) misexpress somatic genes, possibly resulting in PGC loss. Recent studies documented a requirement for Gcl during proteolytic degradation of the terminal patterning determinant, Torso receptor. Here we demonstrate that the somatic determinant of female fate, Sex-lethal (Sxl), is a biologically relevant transcriptional target of Gcl. Underscoring the significance of transcriptional silencing mediated by Gcl, ectopic expression of a degradation-resistant form of Torso (torsoDeg) can activate Sxl transcription in PGCs, whereas simultaneous loss of torso-like (tsl) reinstates the quiescent status of gcl PGCs. Intriguingly, like gcl mutants, embryos derived from mothers expressing torsoDeg in the germline display aberrant spreading of pole plasm RNAs, suggesting that mutual antagonism between Gcl and Torso ensures the controlled release of germ-plasm underlying the germline/soma distinction.
Collapse
Affiliation(s)
- Megan M Colonnetta
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Lauren R Lym
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Lillian Wilkins
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Gretchen Kappes
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Elias A Castro
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Pearl V Ryder
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, United States
| |
Collapse
|
18
|
Lasko P. Patterning the Drosophila embryo: A paradigm for RNA-based developmental genetic regulation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1610. [PMID: 32543002 PMCID: PMC7583483 DOI: 10.1002/wrna.1610] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 12/16/2022]
Abstract
Embryonic anterior–posterior patterning is established in Drosophila melanogaster by maternally expressed genes. The mRNAs of several of these genes accumulate at either the anterior or posterior pole of the oocyte via a number of mechanisms. Many of these mRNAs are also under elaborate translational regulation. Asymmetric RNA localization coupled with spatially restricted translation ensures that their proteins are restricted to the position necessary for the developmental process that they drive. Bicoid (Bcd), the anterior determinant, and Oskar (Osk), the determinant for primordial germ cells and posterior patterning, have been studied particularly closely. In early embryos an anterior–posterior gradient of Bcd is established, activating transcription of different sets of zygotic genes depending on local Bcd concentration. At the posterior pole, Osk seeds formation of polar granules, ribonucleoprotein complexes that accumulate further mRNAs and proteins involved in posterior patterning and germ cell specification. After fertilization, polar granules associate with posterior nuclei and mature into nuclear germ granules. Osk accumulates in these granules, and either by itself or as part of the granules, stimulates germ cell division. This article is categorized under:RNA Export and Localization > RNA Localization Translation > Translation Regulation RNA in Disease and Development > RNA in Development
Collapse
Affiliation(s)
- Paul Lasko
- Department of Biology, McGill University, Montréal, Québec, Canada.,Department of Human Genetics, Radboudumc, Nijmegen, Netherlands
| |
Collapse
|
19
|
Syal S, Ng C, Kim Y, Janbieh J, Govind S, Deshpande G. Reactive oxygen species signaling in primordial germ cell development in Drosophila embryos. Genesis 2020; 58:e23362. [PMID: 32302036 DOI: 10.1002/dvg.23362] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 03/04/2020] [Accepted: 03/23/2020] [Indexed: 12/30/2022]
Abstract
REDOX mechanisms that induce biosynthesis of the reactive oxygen species (ROS) have attracted considerable attention due to both the deleterious and beneficial responses elicited by the reactive radical. In several organisms including Drosophila melanogaster, modulation of ROS activity is thought to be crucial for the maintenance of cell fates in developmental contexts. Interestingly, REDOX mechanisms have been shown to be involved in maintaining progenitor fate of stem cells as well as their proliferation and differentiation. Here, we have explored the possible functions of ROS during proper specification and developmental progression of embryonic primordial germ cells (PGCs). Indicating its potential involvement in these processes, ROS can be detected in the embryonic PGCs and the surrounding somatic cells from very early stages of embryogenesis. Using both "loss" and "gain" of function mutations in two different components of the REDOX pathway, we show that ROS levels are likely to be critical in maintaining germ cell behavior, including their directed migration. Altering the activity of a putative regulator of ROS also adversely influences the ability of PGCs to adhere to one another in cellular blastoderm embryos, suggesting potential involvement of this pathway in orchestrating different phases of germ cell migration.
Collapse
Affiliation(s)
- Sapna Syal
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Chris Ng
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Yunah Kim
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Javier Janbieh
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Shubha Govind
- The Graduate Center of the City University of New York, New York, New York, USA
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| |
Collapse
|
20
|
Venkei ZG, Choi CP, Feng S, Chen C, Jacobsen SE, Kim JK, Yamashita YM. A kinesin Klp10A mediates cell cycle-dependent shuttling of Piwi between nucleus and nuage. PLoS Genet 2020; 16:e1008648. [PMID: 32168327 PMCID: PMC7094869 DOI: 10.1371/journal.pgen.1008648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 03/25/2020] [Accepted: 02/03/2020] [Indexed: 12/26/2022] Open
Abstract
The piRNA pathway protects germline genomes from selfish genetic elements (e.g. transposons) through their transcript cleavage in the cytoplasm and/or their transcriptional silencing in the nucleus. Here, we describe a mechanism by which the nuclear and cytoplasmic arms of the piRNA pathway are linked. We find that during mitosis of Drosophila spermatogonia, nuclear Piwi interacts with nuage, the compartment that mediates the cytoplasmic arm of the piRNA pathway. At the end of mitosis, Piwi leaves nuage to return to the nucleus. Dissociation of Piwi from nuage occurs at the depolymerizing microtubules of the central spindle, mediated by a microtubule-depolymerizing kinesin, Klp10A. Depletion of klp10A delays the return of Piwi to the nucleus and affects piRNA production, suggesting the role of nuclear-cytoplasmic communication in piRNA biogenesis. We propose that cell cycle-dependent communication between the nuclear and cytoplasmic arms of the piRNA pathway may play a previously unappreciated role in piRNA regulation. The piRNA pathway that defends germline from selfish elements operates in two subpathways, one mediated by Piwi in Drosophila to silence transcription of targets in the nucleus and the other mediated by Aub and Ago3 to cleave transcripts of targets in the cytoplasm. How these two subpathways might coordinate with each other, particularly at the cell biological level, remains elusive. This study shows that Piwi interacts with Aub/Ago3 specifically in mitosis in nuage, the organelle that serves as the platform for piRNA cytoplasmic subpathway. Piwi returns to the nucleus at the end of mitosis, and our study suggests that dissociation of Piwi from nuage is facilitated by microtubule depolymerization by a kinesin Klp10A at the central spindle. We propose that cell-cycle-dependent interaction of two piRNA subpathways may play an important role in piRNA production.
Collapse
Affiliation(s)
- Zsolt G. Venkei
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Charlotte P. Choi
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California, United States of America
- Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, California, United States of America
| | - Cuie Chen
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Steven E. Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California, United States of America
- Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, California, United States of America
- Howard Hughes Medical Institute, University of California, Los Angeles, California, United States of America
| | - John K. Kim
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Yukiko M. Yamashita
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- Howard Hughes Medical Institute, University of Michigan Ann Arbor, Michigan, United States of America
- * E-mail:
| |
Collapse
|
21
|
Eichler CE, Hakes AC, Hull B, Gavis ER. Compartmentalized oskar degradation in the germ plasm safeguards germline development. eLife 2020; 9:49988. [PMID: 31909715 PMCID: PMC6986870 DOI: 10.7554/elife.49988] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 01/07/2020] [Indexed: 12/13/2022] Open
Abstract
Partitioning of mRNAs into ribonucleoprotein (RNP) granules supports diverse regulatory programs within the crowded cytoplasm. At least two types of RNP granules populate the germ plasm, a cytoplasmic domain at the posterior of the Drosophila oocyte and embryo. Germ granules deliver mRNAs required for germline development to pole cells, the germ cell progenitors. A second type of RNP granule, here named founder granules, contains oskar mRNA, which encodes the germ plasm organizer. Whereas oskar mRNA is essential for germ plasm assembly during oogenesis, we show that it is toxic to pole cells. Founder granules mediate compartmentalized degradation of oskar during embryogenesis to minimize its inheritance by pole cells. Degradation of oskar in founder granules is temporally and mechanistically distinct from degradation of oskar and other mRNAs during the maternal-to-zygotic transition. Our results show how compartmentalization in RNP granules differentially controls fates of mRNAs localized within the same cytoplasmic domain.
Collapse
Affiliation(s)
- Catherine E Eichler
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Anna C Hakes
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Brooke Hull
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, United States
| |
Collapse
|
22
|
Vo HDL, Wahiduzzaman, Tindell SJ, Zheng J, Gao M, Arkov AL. Protein components of ribonucleoprotein granules from Drosophila germ cells oligomerize and show distinct spatial organization during germline development. Sci Rep 2019; 9:19190. [PMID: 31844131 PMCID: PMC6915754 DOI: 10.1038/s41598-019-55747-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 11/28/2019] [Indexed: 01/11/2023] Open
Abstract
The assembly of large RNA-protein granules occurs in germ cells of many animals and these germ granules have provided a paradigm to study structure-functional aspects of similar structures in different cells. Germ granules in Drosophila oocyte’s posterior pole (polar granules) are composed of RNA, in the form of homotypic clusters, and proteins required for germline development. In the granules, Piwi protein Aubergine binds to a scaffold protein Tudor, which contains 11 Tudor domains. Using a super-resolution microscopy, we show that surprisingly, Aubergine and Tudor form distinct clusters within the same polar granules in early Drosophila embryos. These clusters partially overlap and, after germ cells form, they transition into spherical granules with the structural organization unexpected from these interacting proteins: Aubergine shell around the Tudor core. Consistent with the formation of distinct clusters, we show that Aubergine forms homo-oligomers and using all purified Tudor domains, we demonstrate that multiple domains, distributed along the entire Tudor structure, interact with Aubergine. Our data suggest that in polar granules, Aubergine and Tudor are assembled into distinct phases, partially mixed at their “interaction hubs”, and that association of distinct protein clusters may be an evolutionarily conserved mechanism for the assembly of germ granules.
Collapse
Affiliation(s)
- Hieu D L Vo
- Department of Biological Sciences, Murray State University, Murray, KY, 42071, USA
| | - Wahiduzzaman
- Department of Biological Sciences, Murray State University, Murray, KY, 42071, USA
| | - Samuel J Tindell
- Department of Biological Sciences, Murray State University, Murray, KY, 42071, USA
| | - Jimiao Zheng
- Department of Biological Sciences, Murray State University, Murray, KY, 42071, USA
| | - Ming Gao
- Biology Department, Indiana University Northwest, Gary, IN, 46408, USA
| | - Alexey L Arkov
- Department of Biological Sciences, Murray State University, Murray, KY, 42071, USA.
| |
Collapse
|
23
|
Fang J, Lerit DA. Drosophila pericentrin-like protein promotes the formation of primordial germ cells. Genesis 2019; 58:e23347. [PMID: 31774613 DOI: 10.1002/dvg.23347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/01/2019] [Accepted: 11/09/2019] [Indexed: 11/12/2022]
Abstract
Primordial germ cells (PGCs) are the precursors to the adult germline stem cells that are set aside early during embryogenesis and specified through the inheritance of the germ plasm, which contains the mRNAs and proteins that function as the germline fate determinants. In Drosophila melanogaster, formation of the PGCs requires the microtubule and actin cytoskeletal networks to actively segregate the germ plasm from the soma and physically construct the pole buds (PBs) that protrude from the posterior cortex. Of emerging importance is the central role of centrosomes in the coordination of microtubule dynamics and actin organization to promote PGC development. We previously identified a requirement for the centrosome protein Centrosomin (Cnn) in PGC formation. Cnn interacts directly with Pericentrin-like protein (PLP) to form a centrosome scaffold structure required for pericentriolar material recruitment and organization. In this study, we identify a role for PLP at several discrete steps during PGC development. We find PLP functions in segregating the germ plasm from the soma by regulating microtubule organization and centrosome separation. These activities further contribute to promoting PB protrusion and facilitating the distribution of germ plasm in proliferating PGCs.
Collapse
Affiliation(s)
- Junnan Fang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia
| | - Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia
| |
Collapse
|
24
|
Quan H, Arsala D, Lynch JA. Transcriptomic and functional analysis of the oosome, a unique form of germ plasm in the wasp Nasonia vitripennis. BMC Biol 2019; 17:78. [PMID: 31601213 PMCID: PMC6785909 DOI: 10.1186/s12915-019-0696-7] [Citation(s) in RCA: 3] [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: 01/15/2019] [Accepted: 08/30/2019] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The oosome is the germline determinant in the wasp Nasonia vitripennis and is homologous to the polar granules of Drosophila. Despite a common evolutionary origin and developmental role, the oosome is morphologically quite distinct from polar granules. It is a solid sphere that migrates within the cytoplasm before budding out and forming pole cells. RESULTS To gain an understanding of both the molecular basis of oosome development and the conserved essential features of germ plasm, we quantified and compared transcript levels between embryo fragments that contained the oosome and those that did not. The identity of the differentially localized transcripts indicated that Nasonia uses a distinct set of molecules to carry out conserved germ plasm functions. In addition, functional testing of a sample of localized transcripts revealed potentially novel mechanisms of ribonucleoprotein assembly and pole cell cellularization in the wasp. CONCLUSIONS Our results demonstrate that the composition of germ plasm varies significantly within Holometabola, as very few mRNAs share localization to the oosome and polar granules. Some of this variability appears to be related to the unique properties of the oosome relative to the polar granules in Drosophila, and some may be related to differences in pole formation between species. This work will serve as the basis for further investigation into the patterns of germline determinant evolution among insects, the molecular basis of the unique properties of the oosome, and the incorporation of novel components into developmental networks.
Collapse
Affiliation(s)
- Honghu Quan
- Department of Pathology and Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105 USA
| | - Deanna Arsala
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Jeremy A. Lynch
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607 USA
| |
Collapse
|
25
|
Trcek T, Lehmann R. Germ granules in Drosophila. Traffic 2019; 20:650-660. [PMID: 31218815 PMCID: PMC6771631 DOI: 10.1111/tra.12674] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/26/2019] [Accepted: 06/14/2019] [Indexed: 12/22/2022]
Abstract
Germ granules are hallmarks of all germ cells. Early ultrastructural studies in Drosophila first described these membraneless granules in the oocyte and early embryo as filled with amorphous to fibrillar material mixed with RNA. Genetic studies identified key protein components and specific mRNAs that regulate germ cell‐specific functions. More recently these ultrastructural studies have been complemented by biophysical analysis describing germ granules as phase‐transitioned condensates. In this review, we provide an overview that connects the composition of germ granules with their function in controlling germ cell specification, formation and migration, and illuminate these mysterious condensates as the gatekeepers of the next generation.
Collapse
Affiliation(s)
- Tatjana Trcek
- HHMI, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, New York
| | - Ruth Lehmann
- HHMI, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, New York
| |
Collapse
|
26
|
Kina H, Yoshitani T, Hanyu-Nakamura K, Nakamura A. Rapid and efficient generation of GFP-knocked-in Drosophila by the CRISPR-Cas9-mediated genome editing. Dev Growth Differ 2019; 61:265-275. [PMID: 31037730 DOI: 10.1111/dgd.12607] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/20/2019] [Accepted: 03/21/2019] [Indexed: 11/30/2022]
Abstract
The CRISPR-Cas9 technology has been a powerful means to manipulate the genome in a wide range of organisms. A series of GFP knocked-in (GFPKI ) Drosophila strains have been generated through CRISPR-Cas9-induced double strand breaks coupled with homology-directed repairs in the presence of donor plasmids. They visualized specific cell types or intracellular structures in both fixed and live specimen. We provide a rapid and efficient strategy to identify KI lines. This method requires neither co-integration of a selection marker nor prior establishment of sgRNA-expressing transgenic lines. The injection of the mixture of a sgRNA/Cas9 expression plasmid and a donor plasmid into cleavage stage embryos efficiently generated multiple independent KI lines. A PCR-based selection allows to identify KI fly lines at the F1 generation (approximately 4 weeks after injection). These GFPKI strains have been deposited in the Kyoto Drosophila stock center, and made freely available to researchers at non-profit organizations. Thus, they will be useful resources for Drosophila research.
Collapse
Affiliation(s)
- Hirono Kina
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan.,School of Pharmacy, Kumamoto University, Kumamoto, Japan
| | - Takashi Yoshitani
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan.,School of Pharmacy, Kumamoto University, Kumamoto, Japan
| | - Kazuko Hanyu-Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Akira Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan.,School of Pharmacy, Kumamoto University, Kumamoto, Japan.,Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| |
Collapse
|
27
|
Bioinformatics Approaches to Gain Insights into cis-Regulatory Motifs Involved in mRNA Localization. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:165-194. [PMID: 31811635 DOI: 10.1007/978-3-030-31434-7_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Messenger RNA (mRNA) is a fundamental intermediate in the expression of proteins. As an integral part of this important process, protein production can be localized by the targeting of mRNA to a specific subcellular compartment. The subcellular destination of mRNA is suggested to be governed by a region of its primary sequence or secondary structure, which consequently dictates the recruitment of trans-acting factors, such as RNA-binding proteins or regulatory RNAs, to form a messenger ribonucleoprotein particle. This molecular ensemble is requisite for precise and spatiotemporal control of gene expression. In the context of RNA localization, the description of the binding preferences of an RNA-binding protein defines a motif, and one, or more, instance of a given motif is defined as a localization element (zip code). In this chapter, we first discuss the cis-regulatory motifs previously identified as mRNA localization elements. We then describe motif representation in terms of entropy and information content and offer an overview of motif databases and search algorithms. Finally, we provide an outline of the motif topology of asymmetrically localized mRNA molecules.
Collapse
|
28
|
Blake-Hedges C, Megraw TL. Coordination of Embryogenesis by the Centrosome in Drosophila melanogaster. Results Probl Cell Differ 2019; 67:277-321. [PMID: 31435800 DOI: 10.1007/978-3-030-23173-6_12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The first 3 h of Drosophila melanogaster embryo development are exemplified by rapid nuclear divisions within a large syncytium, transforming the zygote to the cellular blastoderm after 13 successive cleavage divisions. As the syncytial embryo develops, it relies on centrosomes and cytoskeletal dynamics to transport nuclei, maintain uniform nuclear distribution throughout cleavage cycles, ensure generation of germ cells, and coordinate cellularization. For the sake of this review, we classify six early embryo stages that rely on processes coordinated by the centrosome and its regulation of the cytoskeleton. The first stage features migration of one of the female pronuclei toward the male pronucleus following maturation of the first embryonic centrosomes. Two subsequent stages distribute the nuclei first axially and then radially in the embryo. The remaining three stages involve centrosome-actin dynamics that control cortical plasma membrane morphogenesis. In this review, we highlight the dynamics of the centrosome and its role in controlling the six stages that culminate in the cellularization of the blastoderm embryo.
Collapse
Affiliation(s)
- Caitlyn Blake-Hedges
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA
| |
Collapse
|
29
|
Eagle WVI, Yeboah-Kordieh DK, Niepielko MG, Gavis ER. Distinct cis-acting elements mediate targeting and clustering of Drosophila polar granule mRNAs. Development 2018; 145:dev.164657. [PMID: 30333216 DOI: 10.1242/dev.164657] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 09/18/2018] [Indexed: 12/11/2022]
Abstract
Specification and development of Drosophila germ cells depend on molecular determinants within the germ plasm, a specialized cytoplasmic domain at the posterior of the embryo. Localization of numerous mRNAs to the germ plasm occurs by their incorporation, as single-transcript ribonucleoprotein (RNP) particles, into complex RNP granules called polar granules. Incorporation of mRNAs into polar granules is followed by recruitment of additional like transcripts to form discrete homotypic clusters. The cis-acting localization signals that target mRNAs to polar granules and promote homotypic clustering remain largely uncharacterized. Here, we show that the polar granule component (pgc) and germ cell-less (gcl) 3' untranslated regions contain complex localization signals comprising multiple, independently weak and partially functionally redundant localization elements (LEs). We demonstrate that targeting of pgc to polar granules and self-assembly into homotypic clusters are functionally separable processes mediated by distinct classes of LEs. We identify a sequence motif shared by other polar granule mRNAs that contributes to homotypic clustering. Our results suggest that mRNA localization signal complexity may be a feature required by the targeting and self-recruitment mechanism that drives germ plasm mRNA localization.
Collapse
Affiliation(s)
- Whitby V I Eagle
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | | | - Matthew G Niepielko
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| |
Collapse
|
30
|
Kistler KE, Trcek T, Hurd TR, Chen R, Liang FX, Sall J, Kato M, Lehmann R. Phase transitioned nuclear Oskar promotes cell division of Drosophila primordial germ cells. eLife 2018; 7:37949. [PMID: 30260314 PMCID: PMC6191285 DOI: 10.7554/elife.37949] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 09/09/2018] [Indexed: 12/25/2022] Open
Abstract
Germ granules are non-membranous ribonucleoprotein granules deemed the hubs for post-transcriptional gene regulation and functionally linked to germ cell fate across species. Little is known about the physical properties of germ granules and how these relate to germ cell function. Here we study two types of germ granules in the Drosophila embryo: cytoplasmic germ granules that instruct primordial germ cells (PGCs) formation and nuclear germ granules within early PGCs with unknown function. We show that cytoplasmic and nuclear germ granules are phase transitioned condensates nucleated by Oskar protein that display liquid as well as hydrogel-like properties. Focusing on nuclear granules, we find that Oskar drives their formation in heterologous cell systems. Multiple, independent Oskar protein domains synergize to promote granule phase separation. Deletion of Oskar’s nuclear localization sequence specifically ablates nuclear granules in cell systems. In the embryo, nuclear germ granules promote germ cell divisions thereby increasing PGC number for the next generation.
Collapse
Affiliation(s)
- Kathryn E Kistler
- Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States.,Department of Molecular and Cellular Biology, University of Washington, Washington, United States
| | - Tatjana Trcek
- Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States
| | - Thomas R Hurd
- Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States.,Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Ruoyu Chen
- Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States
| | - Feng-Xia Liang
- Department of Cell Biology, NYU School of Medicine, New York, United States.,DART Microscopy Laboratory, NYU Langone Health, New York, United States
| | - Joseph Sall
- DART Microscopy Laboratory, NYU Langone Health, New York, United States
| | - Masato Kato
- Department of Biochemistry, University of Texas Southwestern Medical Center, Texas, United States
| | - Ruth Lehmann
- Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States.,Department of Cell Biology, NYU School of Medicine, New York, United States
| |
Collapse
|
31
|
Ote M, Yamamoto D. The Wolbachia protein TomO interacts with a host RNA to induce polarization defects in Drosophila oocytes. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2018; 99:e21475. [PMID: 29851149 DOI: 10.1002/arch.21475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Wolbachia is an endosymbiont prevalent in arthropods. To maximize its transmission thorough the female germline, Wolbachia induces in infected hosts male-to-female transformation, male killing, parthenogenesis, and cytoplasmic incompatibility, depending on the host species and Wolbachia strain involved. However, the molecular mechanisms underlying these host manipulations by Wolbachia remain largely unknown. The Wolbachia strain wMel, an inhabitant of Drosophila melanogaster, impairs host oogenesis only when transplanted into a heterologous host, for example, Drosophila simulans. We found that egg polarity defects induced by wMel infection in D. simulans can be recapitulated in the natural host D. melanogaster by transgenic overexpression of a variant of the Wolbachia protein Toxic manipulator of oogenesis (TomO), TomOwMel∆HS , in the female germline. RNA immunoprecipitation assays demonstrated that TomO physically associates with orb mRNA, which, as a result, fails to interact with the translation repressor Cup. This leads to precocious translation of Orb, a posterior determinant, and thereby to the misspecification of oocytes and accompanying polarity defects. We propose that the ability of TomO to bind to orb mRNA might provide a means for Wolbachia to enter the oocyte located at the posterior end of the egg chamber, thereby accomplishing secure maternal transmission thorough the female germline.
Collapse
Affiliation(s)
- Manabu Ote
- Division of Neurogenetics, Tohoku University, Sendai, Miyagi, Japan
| | | |
Collapse
|
32
|
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.
Collapse
Affiliation(s)
- Beat Suter
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland.
| |
Collapse
|
33
|
Tillery MML, Blake-Hedges C, Zheng Y, Buchwalter RA, Megraw TL. Centrosomal and Non-Centrosomal Microtubule-Organizing Centers (MTOCs) in Drosophila melanogaster. Cells 2018; 7:E121. [PMID: 30154378 PMCID: PMC6162459 DOI: 10.3390/cells7090121] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022] Open
Abstract
The centrosome is the best-understood microtubule-organizing center (MTOC) and is essential in particular cell types and at specific stages during Drosophila development. The centrosome is not required zygotically for mitosis or to achieve full animal development. Nevertheless, centrosomes are essential maternally during cleavage cycles in the early embryo, for male meiotic divisions, for efficient division of epithelial cells in the imaginal wing disc, and for cilium/flagellum assembly in sensory neurons and spermatozoa. Importantly, asymmetric and polarized division of stem cells is regulated by centrosomes and by the asymmetric regulation of their microtubule (MT) assembly activity. More recently, the components and functions of a variety of non-centrosomal microtubule-organizing centers (ncMTOCs) have begun to be elucidated. Throughout Drosophila development, a wide variety of unique ncMTOCs form in epithelial and non-epithelial cell types at an assortment of subcellular locations. Some of these cell types also utilize the centrosomal MTOC, while others rely exclusively on ncMTOCs. The impressive variety of ncMTOCs being discovered provides novel insight into the diverse functions of MTOCs in cells and tissues. This review highlights our current knowledge of the composition, assembly, and functional roles of centrosomal and non-centrosomal MTOCs in Drosophila.
Collapse
Affiliation(s)
- Marisa M L Tillery
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Caitlyn Blake-Hedges
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Yiming Zheng
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| |
Collapse
|
34
|
Bornens M. Cell polarity: having and making sense of direction-on the evolutionary significance of the primary cilium/centrosome organ in Metazoa. Open Biol 2018; 8:180052. [PMID: 30068565 PMCID: PMC6119866 DOI: 10.1098/rsob.180052] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 07/05/2018] [Indexed: 12/13/2022] Open
Abstract
Cell-autonomous polarity in Metazoans is evolutionarily conserved. I assume that permanent polarity in unicellular eukaryotes is required for cell motion and sensory reception, integration of these two activities being an evolutionarily constrained function. Metazoans are unique in making cohesive multicellular organisms through complete cell divisions. They evolved a primary cilium/centrosome (PC/C) organ, ensuring similar functions to the basal body/flagellum of unicellular eukaryotes, but in different cells, or in the same cell at different moments. The possibility that this innovation contributed to the evolution of individuality, in being instrumental in the early specification of the germ line during development, is further discussed. Then, using the example of highly regenerative organisms like planarians, which have lost PC/C organ in dividing cells, I discuss the possibility that part of the remodelling necessary to reach a new higher-level unit of selection in multi-cellular organisms has been triggered by conflicts among individual cell polarities to reach an organismic polarity. Finally, I briefly consider organisms with a sensorimotor organ like the brain that requires exceedingly elongated polarized cells for its activity. I conclude that beyond critical consequences for embryo development, the conservation of cell-autonomous polarity in Metazoans had far-reaching implications for the evolution of individuality.
Collapse
Affiliation(s)
- Michel Bornens
- Institut Curie, PSL Research University, CNRS - UMR 144, 75005 Paris, France
| |
Collapse
|
35
|
Lengefeld J, Barral Y. Asymmetric Segregation of Aged Spindle Pole Bodies During Cell Division: Mechanisms and Relevance Beyond Budding Yeast? Bioessays 2018; 40:e1800038. [DOI: 10.1002/bies.201800038] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/21/2018] [Indexed: 01/21/2023]
Affiliation(s)
- Jette Lengefeld
- Institute of Biochemistry; ETH Zurich; Otto-Stern-Weg 3 8093 Zurich Switzerland
- David H. Koch Institute for Integrative Cancer Research; Massachusetts Institute of Technology; Cambridge, Massachusetts 02139 USA
| | - Yves Barral
- Institute of Biochemistry; ETH Zurich; Otto-Stern-Weg 3 8093 Zurich Switzerland
| |
Collapse
|
36
|
Stochastic Seeding Coupled with mRNA Self-Recruitment Generates Heterogeneous Drosophila Germ Granules. Curr Biol 2018; 28:1872-1881.e3. [PMID: 29861136 DOI: 10.1016/j.cub.2018.04.037] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/27/2018] [Accepted: 04/12/2018] [Indexed: 11/22/2022]
Abstract
The formation of ribonucleoprotein assemblies called germ granules is a conserved feature of germline development. In Drosophila, germ granules form at the posterior of the oocyte in a specialized cytoplasm called the germ plasm, which specifies germline fate during embryogenesis. mRNAs, including nanos (nos) and polar granule component (pgc), that function in germline development are localized to the germ plasm through their incorporation into germ granules, which deliver them to the primordial germ cells. Germ granules are nucleated by Oskar (Osk) protein and contain varying combinations and quantities of their constituent mRNAs, which are organized as spatially distinct, multi-copy homotypic clusters. The process that gives rise to such heterogeneous yet organized granules remains unknown. Here, we show that individual nos and pgc transcripts can populate the same nascent granule, and these first transcripts then act as seeds, recruiting additional like transcripts to form homotypic clusters. Within a granule, homotypic clusters grow independently of each other but depend on the simultaneous acquisition of additional Osk. Although granules can contain multiple clusters of a particular mRNA, granule mRNA content is dominated by cluster size. These results suggest that the accumulation of mRNAs in the germ plasm is controlled by the mRNAs themselves through their ability to form homotypic clusters; thus, RNA self-association drives germ granule mRNA localization. We propose that a stochastic seeding and self-recruitment mechanism enables granules to simultaneously incorporate many different mRNAs while ensuring that each becomes enriched to a functional threshold.
Collapse
|
37
|
Ryder PV, Lerit DA. RNA localization regulates diverse and dynamic cellular processes. Traffic 2018; 19:496-502. [PMID: 29653028 DOI: 10.1111/tra.12571] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 02/06/2023]
Abstract
At the nexus of specialized cellular responses are localized enrichments of protein activity. The localization of messenger RNA (mRNA) coupled with translational control often plays a crucial role in the generation of protein concentrations at defined subcellular domains. Although mRNA localization is classically associated with large specialized cells, such as neurons and embryos, RNA localization is a highly conserved paradigm of post-transcriptional regulation observed in diverse cellular contexts. Functions of localized mRNAs extend far beyond the well-studied examples of neuronal polarization and developmental patterning. Since the initial discovery of the intracellular localization of cytoskeletal mRNAs within migrating cells, hundreds of mRNAs are now known to be enriched at specific organelles where they contribute to cell function. In this short review, we discuss basic principles regulating RNA localization and consider the contribution of localized mRNA to several essential cellular behaviors. We consider RNA localization as a mechanism with widespread implications for cellular function.
Collapse
Affiliation(s)
- Pearl V Ryder
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia
| | - Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia
| |
Collapse
|
38
|
Lerit DA, Shebelut CW, Lawlor KJ, Rusan NM, Gavis ER, Schedl P, Deshpande G. Germ Cell-less Promotes Centrosome Segregation to Induce Germ Cell Formation. Cell Rep 2017; 18:831-839. [PMID: 28122234 DOI: 10.1016/j.celrep.2016.12.074] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/22/2016] [Accepted: 12/22/2016] [Indexed: 11/12/2022] Open
Abstract
The primordial germ cells (PGCs) specified during embryogenesis serve as progenitors to the adult germline stem cells. In Drosophila, the proper specification and formation of PGCs require both centrosomes and germ plasm, which contains the germline determinants. Centrosomes are microtubule (MT)-organizing centers that ensure the faithful segregation of germ plasm into PGCs. To date, mechanisms that modulate centrosome behavior to engineer PGC development have remained elusive. Only one germ plasm component, Germ cell-less (Gcl), is known to play a role in PGC formation. Here, we show that Gcl engineers PGC formation by regulating centrosome dynamics. Loss of gcl leads to aberrant centrosome separation and elaboration of the astral MT network, resulting in inefficient germ plasm segregation and aborted PGC cellularization. Importantly, compromising centrosome separation alone is sufficient to mimic the gcl loss-of-function phenotypes. We conclude Gcl functions as a key regulator of centrosome separation required for proper PGC development.
Collapse
Affiliation(s)
- Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Conrad W Shebelut
- School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Kristen J Lawlor
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| |
Collapse
|
39
|
DeHaan H, McCambridge A, Armstrong B, Cruse C, Solanki D, Trinidad JC, Arkov AL, Gao M. An in vivo proteomic analysis of the Me31B interactome in Drosophila germ granules. FEBS Lett 2017; 591:3536-3547. [PMID: 28945271 DOI: 10.1002/1873-3468.12854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/07/2017] [Accepted: 09/15/2017] [Indexed: 12/11/2022]
Abstract
Drosophila Me31B is a conserved protein of germ granules, ribonucleoprotein complexes essential for germ cell development. Me31B post-transcriptionally regulates mRNAs by interacting with other germ granule proteins. However, a Me31B interactome is lacking. Here, we use an in vivo proteomics approach to show that the Me31B interactome contains polypeptides from four functional groups: RNA regulatory proteins, glycolytic enzymes, cytoskeleton/motor proteins, and germ plasm components. We further show that Me31B likely colocalizes with the germ plasm components Tudor (Tud), Vasa, and Aubergine in the nuage and germ plasm and provide evidence that Me31B may directly bind to Tud in a symmetrically dimethylated arginine-dependent manner. Our study supports the role of Me31B in RNA regulation and suggests its novel roles in germ granule assembly and function.
Collapse
Affiliation(s)
- Hunter DeHaan
- Biology Department, Indiana University Northwest, Gary, IN, USA
| | | | | | - Carlie Cruse
- Biology Department, Indiana University Northwest, Gary, IN, USA
| | - Dhruv Solanki
- Biology Department, Indiana University Northwest, Gary, IN, USA
| | | | - Alexey L Arkov
- Department of Biological Sciences, Murray State University, Murray, KY, USA
| | - Ming Gao
- Biology Department, Indiana University Northwest, Gary, IN, USA
| |
Collapse
|
40
|
Bilinski SM, Jaglarz MK, Tworzydlo W. The Pole (Germ) Plasm in Insect Oocytes. Results Probl Cell Differ 2017; 63:103-126. [PMID: 28779315 DOI: 10.1007/978-3-319-60855-6_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Animal germline cells are specified either through zygotic induction or cytoplasmic inheritance. Zygotic induction takes place in mid- or late embryogenesis and requires cell-to-cell signaling leading to the acquisition of germline fate de novo. In contrast, cytoplasmic inheritance involves formation of a specific, asymmetrically localized oocyte region, termed the germ (pole) plasm. This region contains maternally provided germline determinants (mRNAs, proteins) that are capable of inducing germline fate in a subset of embryonic cells. Recent data indicate that among insects, the zygotic induction represents an ancestral condition, while the cytoplasmic inheritance evolved at the base of Holometabola or in the last common ancestor of Holometabola and its sister taxon, Paraneoptera.In this chapter, we first describe subsequent stages of morphogenesis of the pole plasm and polar granules in the model organism, Drosophila melanogaster. Then, we present an overview of morphology and cytoarchitecture of the pole plasm in various holometabolan and paraneopteran insect species. Finally, we focus on phylogenetic hypotheses explaining the known distribution of two different strategies of germline specification among insects.
Collapse
Affiliation(s)
- Szczepan M Bilinski
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland.
| | - Mariusz K Jaglarz
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland
| | - Waclaw Tworzydlo
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland
| |
Collapse
|
41
|
LeBlanc MG, Lehmann R. Domain-specific control of germ cell polarity and migration by multifunction Tre1 GPCR. J Cell Biol 2017; 216:2945-2958. [PMID: 28687666 PMCID: PMC5584160 DOI: 10.1083/jcb.201612053] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 04/28/2017] [Accepted: 06/08/2017] [Indexed: 11/22/2022] Open
Abstract
Migrating cells encounter directional cues to reach their destinations, often using G protein–coupled receptors (GPCRs) to interpret such cues. LeBlanc and Lehmann show that two highly conserved domains in the GPCR Tre1 mediate distinct migratory responses in germ cells via separate signaling pathways, one regulating cell polarization and the other directional migration. The migration of primordial germ cells (PGCs) from their place of origin to the embryonic gonad is an essential reproductive feature in many animal species. In Drosophila melanogaster, a single G protein–coupled receptor, Trapped in endoderm 1 (Tre1), mediates germ cell polarization at the onset of active migration and directs subsequent migration of PGCs through the midgut primordium. How these different aspects of cell behavior are coordinated through a single receptor is not known. We demonstrate that two highly conserved domains, the E/N/DRY and NPxxY motifs, have overlapping and unique functions in Tre1. The Tre1-NRY domain via G protein signaling is required for reading and responding to guidance and survival cues controlled by the lipid phosphate phosphatases Wunen and Wunen2. In contrast, the Tre1-NPIIY domain has a separate role in Rho1- and E-cadherin–mediated polarization at the initiation stage independent of G protein signaling. We propose that this bifurcation of the Tre1 G protein–coupled receptor signaling response via G protein–dependent and independent branches enables distinct spatiotemporal regulation of germ cell migration.
Collapse
Affiliation(s)
- Michelle G LeBlanc
- Howard Hughes Medical Institute, Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, NY.,Department of Cell Biology, New York University School of Medicine, New York, NY
| | - Ruth Lehmann
- Howard Hughes Medical Institute, Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, NY .,Department of Cell Biology, New York University School of Medicine, New York, NY
| |
Collapse
|
42
|
Dehghani M, Lasko P. Multiple Functions of the DEAD-Box Helicase Vasa in Drosophila Oogenesis. Results Probl Cell Differ 2017; 63:127-147. [PMID: 28779316 DOI: 10.1007/978-3-319-60855-6_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The DEAD-box helicase Vasa (Vas) has been most extensively studied in the fruit fly, Drosophila melanogaster, and numerous roles for it in germline development have been discovered. Here, we summarize the present state of knowledge about processes during oogenesis that involve Vas, as well as functions of Vas as a maternal determinant of embryonic spatial patterning and germ cell specification. We review literature that implicates Vas in Piwi-interacting RNA (piRNA) biogenesis in germline cells and in regulating mitosis in germline stem cells (GSCs). We describe the functions of Vas in translational activation of two mRNAs, gurken (grk) and mei-P26, which encode proteins that are important regulators of developmental processes, as Grk specifies both the dorsal-ventral and the anterior-posterior axis of the embryo and Mei-P26 promotes GSC differentiation. The role of Vas in assembly of polar granules, ribonucleoprotein particles that accumulate in the posterior pole plasm of the oocyte and are essential for germ cell specification and posterior embryonic patterning, is also described.
Collapse
Affiliation(s)
- Mehrnoush Dehghani
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec, Canada, H3G 0B1
| | - Paul Lasko
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec, Canada, H3G 0B1.
| |
Collapse
|
43
|
Zheng J, Gao M, Huynh N, Tindell SJ, Vo HDL, McDonald WH, Arkov AL. In vivo mapping of a dynamic ribonucleoprotein granule interactome in early Drosophila embryos. FEBS Open Bio 2016; 6:1248-1256. [PMID: 28203524 PMCID: PMC5302063 DOI: 10.1002/2211-5463.12144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/21/2016] [Accepted: 10/03/2016] [Indexed: 12/22/2022] Open
Abstract
Macromolecular complexes and organelles play crucial roles within cells, but their native architectures are often unknown. Here, we use an evolutionarily conserved germline organelle, the germ granule, as a paradigm. In Drosophila embryos, we map one of its interactomes using a novel in vivo crosslinking approach that employs two interacting granule proteins and determines their common neighbor molecules. We identified an in vivo granule assembly of Tudor, Aubergine, motor and metabolic proteins, and RNA helicases, and provide evidence for direct interactions within this assembly using purified components. Our study indicates that germ granules contain efficient biochemical reactors involved in post‐transcriptional gene regulation.
Collapse
Affiliation(s)
- Jimiao Zheng
- Department of Biological Sciences Murray State University USA
| | - Ming Gao
- Biology Department Indiana University Northwest Gary IN USA
| | - Nhan Huynh
- Department of Biological Sciences Murray State University USA; Present address: University of Alberta Edmonton AB Canada
| | | | - Hieu D L Vo
- Department of Biological Sciences Murray State University USA
| | - W Hayes McDonald
- Department of Biochemistry Mass Spectrometry Research Center Vanderbilt University School of Medicine Nashville TN USA
| | - Alexey L Arkov
- Department of Biological Sciences Murray State University USA
| |
Collapse
|
44
|
Dehghani M, Lasko P. C-terminal residues specific to Vasa among DEAD-box helicases are required for its functions in piRNA biogenesis and embryonic patterning. Dev Genes Evol 2016; 226:401-412. [DOI: 10.1007/s00427-016-0560-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/09/2016] [Indexed: 10/21/2022]
|
45
|
Kowanda M, Bergalet J, Wieczorek M, Brouhard G, Lécuyer É, Lasko P. Loss of function of the Drosophila Ninein-related centrosomal protein Bsg25D causes mitotic defects and impairs embryonic development. Biol Open 2016; 5:1040-51. [PMID: 27422905 PMCID: PMC5004617 DOI: 10.1242/bio.019638] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The centrosome-associated proteins Ninein (Nin) and Ninein-like protein (Nlp) play significant roles in microtubule stability, nucleation and anchoring at the centrosome in mammalian cells. Here, we investigate Blastoderm specific gene 25D (Bsg25D), which encodes the only Drosophila protein that is closely related to Nin and Nlp. In early embryos, we find that Bsg25D mRNA and Bsg25D protein are closely associated with centrosomes and astral microtubules. We show that sequences within the coding region and 3′UTR of Bsg25D mRNAs are important for proper localization of this transcript in oogenesis and embryogenesis. Ectopic expression of eGFP-Bsg25D from an unlocalized mRNA disrupts microtubule polarity in mid-oogenesis and compromises the distribution of the axis polarity determinant Gurken. Using total internal reflection fluorescence microscopy, we show that an N-terminal fragment of Bsg25D can bind microtubules in vitro and can move along them, predominantly toward minus-ends. While flies homozygous for a Bsg25D null mutation are viable and fertile, 70% of embryos lacking maternal and zygotic Bsg25D do not hatch and exhibit chromosome segregation defects, as well as detachment of centrosomes from mitotic spindles. We conclude that Bsg25D is a centrosomal protein that, while dispensable for viability, nevertheless helps ensure the integrity of mitotic divisions in Drosophila. Summary: In humans, mutations in Ninein or Ninein-like protein result in microcephaly and other severe diseases. We show that while flies lacking the Ninein orthologue can survive, many die as embryos with defects in mitosis.
Collapse
Affiliation(s)
- Michelle Kowanda
- Department of Biology, McGill University, Montréal, Québec H3G 0B1, Canada
| | - Julie Bergalet
- RNA Biology Unit, Institut de recherches cliniques de Montréal (IRCM), Montréal, Québec H2W 1R7, Canada
| | - Michal Wieczorek
- Department of Biology, McGill University, Montréal, Québec H3G 0B1, Canada
| | - Gary Brouhard
- Department of Biology, McGill University, Montréal, Québec H3G 0B1, Canada
| | - Éric Lécuyer
- RNA Biology Unit, Institut de recherches cliniques de Montréal (IRCM), Montréal, Québec H2W 1R7, Canada Département de Biochimie, Université de Montréal, Montréal, Québec H3T 1J4, Canada Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Paul Lasko
- Department of Biology, McGill University, Montréal, Québec H3G 0B1, Canada
| |
Collapse
|
46
|
Varela N, Aranguiz A, Lizama C, Sepulveda H, Antonelli M, Thaler R, Moreno RD, Montecino M, Stein GS, van Wijnen AJ, Galindo M. Mitotic Inheritance of mRNA Facilitates Translational Activation of the Osteogenic-Lineage Commitment Factor Runx2 in Progeny of Osteoblastic Cells. J Cell Physiol 2016; 231:1001-14. [PMID: 26381402 PMCID: PMC5812339 DOI: 10.1002/jcp.25188] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 09/03/2015] [Indexed: 12/24/2022]
Abstract
Epigenetic mechanisms mediate the acquisition of specialized cellular phenotypes during tissue development, maintenance and repair. When phenotype-committed cells transit through mitosis, chromosomal condensation counteracts epigenetic activation of gene expression. Subsequent post-mitotic re-activation of transcription depends on epigenetic DNA and histone modifications, as well as other architecturally bound proteins that "bookmark" the genome. Osteogenic lineage commitment, differentiation and progenitor proliferation require the bone-related runt-related transcription factor Runx2. Here, we characterized a non-genomic mRNA mediated mechanism by which osteoblast precursors retain their phenotype during self-renewal. We show that osteoblasts produce maximal levels of Runx2 mRNA, but not protein, prior to mitotic cell division. Runx2 mRNA partitions symmetrically between daughter cells in a non-chromosomal tubulin-containing compartment. Subsequently, transcription-independent de novo synthesis of Runx2 protein in early G1 phase results in increased functional interactions of Runx2 with a representative osteoblast-specific target gene (osteocalcin/BGLAP2) in chromatin. Somatic transmission of Runx2 mRNAs in osteoblasts and osteosarcoma cells represents a versatile mechanism for translational rather than transcriptional induction of this principal gene regulator to maintain osteoblast phenotype identity after mitosis.
Collapse
Affiliation(s)
- Nelson Varela
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, University of Chile, Santiago, Chile
- Department of Medical Technology, Faculty of Medicine, University of Chile, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, University of Chile, Santiago, Chile
| | - Alejandra Aranguiz
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, University of Chile, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, University of Chile, Santiago, Chile
| | - Carlos Lizama
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Hugo Sepulveda
- Center for Biomedical Research and FONDAP Center for Genome Regulation, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Marcelo Antonelli
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, University of Chile, Santiago, Chile
| | - Roman Thaler
- Departments of Orthopedic Surgery & Biochemistry and Molecular Biology, Mayo Clinic, 200 First Street S.W., MSB 3-69, Rochester, MN 55905
| | - Ricardo D. Moreno
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Martin Montecino
- Center for Biomedical Research and FONDAP Center for Genome Regulation, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Gary S. Stein
- Department of Biochemistry, HSRF 326, Vermont Cancer Center for Basic and Translational Research, University of Vermont Medical School, Burlington, VT
| | - Andre J. van Wijnen
- Departments of Orthopedic Surgery & Biochemistry and Molecular Biology, Mayo Clinic, 200 First Street S.W., MSB 3-69, Rochester, MN 55905
| | - Mario Galindo
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, University of Chile, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, University of Chile, Santiago, Chile
| |
Collapse
|
47
|
Abbaszadeh EK, Gavis ER. Fixed and live visualization of RNAs in Drosophila oocytes and embryos. Methods 2016; 98:34-41. [PMID: 26827935 PMCID: PMC4808400 DOI: 10.1016/j.ymeth.2016.01.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 01/23/2016] [Accepted: 01/27/2016] [Indexed: 12/21/2022] Open
Abstract
The ability to visualize RNA in situ is essential to dissect mechanisms for the temporal and spatial regulation of gene expression that drives development. Although considerable attention has been focused on transcriptional control, studies in model organisms like Drosophila have highlighted the importance of post-transcriptional mechanisms - most notably intracellular mRNA localization - in the formation and patterning of the body axes, specification of cell fates, and polarized cell functions. Our understanding of both types of regulation has been greatly advanced by technological innovations that enable a combination of highly quantitative and dynamic analysis of RNA. This review presents two methods, single molecule fluorescence in situ hybridization for high resolution quantitative RNA detection in fixed Drosophila oocytes and embryos and genetically encoded fluorescent RNA labeling for detection in live cells.
Collapse
Affiliation(s)
- Evan K Abbaszadeh
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States.
| |
Collapse
|
48
|
Yakovlev KV. Localization of germ plasm-related structures during sea urchin oogenesis. Dev Dyn 2015; 245:56-66. [PMID: 26385846 DOI: 10.1002/dvdy.24348] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/12/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Animal germ cells have specific organelles that are similar to ribonucleoprotein complex, called germ plasm, which is accumulated in eggs. Germ plasm is essential for inherited mechanism of germ line segregation in early embryogenesis. Sea urchins have early germ line segregation in early embryogenesis. Nevertheless, organization of germ plasm-related organelles and their molecular composition are still unclear. Another issue is whether maternally accumulated germ plasm exists in the sea urchin eggs. RESULTS I analyzed intracellular localization of germ plasm during oogenesis in sea urchin Strongylocentrotus intermedius by using morphological approach and immunocytochemical detection of Vasa, a germ plasm marker. All ovarian germ cells have germ plasm-related organelles in the form of germ granules, Balbiani bodies, and perinuclear nuage found previously in germ cells in other animals. Maternal germ plasm is accumulated in late oogenesis at the cell periphery. Cytoskeletal drug treatment showed an association of Vasa-positive granules with actin filaments in the egg cortex. CONCLUSIONS All female germ cells of sea urchins have germ plasm-related organelles. Eggs have a maternally accumulated germ plasm associated with cortical cytoskeleton. These findings correlate with early segregation of germ line in sea urchins.
Collapse
Affiliation(s)
- Konstantin V Yakovlev
- Laboratory of Cytotechnology, A.V. Zhirmunsky Institute of Marine Biology of the Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia
| |
Collapse
|
49
|
Lerit DA, Jordan HA, Poulton JS, Fagerstrom CJ, Galletta BJ, Peifer M, Rusan NM. Interphase centrosome organization by the PLP-Cnn scaffold is required for centrosome function. J Cell Biol 2015; 210:79-97. [PMID: 26150390 PMCID: PMC4494003 DOI: 10.1083/jcb.201503117] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cnn and PLP directly interact at two defined sites to coordinate the cell cycle–dependent rearrangement and scaffolding activity of the centrosome to permit normal centrosome organization, cell division, and embryonic viability. Pericentriolar material (PCM) mediates the microtubule (MT) nucleation and anchoring activity of centrosomes. A scaffold organized by Centrosomin (Cnn) serves to ensure proper PCM architecture and functional changes in centrosome activity with each cell cycle. Here, we investigate the mechanisms that spatially restrict and temporally coordinate centrosome scaffold formation. Focusing on the mitotic-to-interphase transition in Drosophila melanogaster embryos, we show that the elaboration of the interphase Cnn scaffold defines a major structural rearrangement of the centrosome. We identify an unprecedented role for Pericentrin-like protein (PLP), which localizes to the tips of extended Cnn flares, to maintain robust interphase centrosome activity and promote the formation of interphase MT asters required for normal nuclear spacing, centrosome segregation, and compartmentalization of the syncytial embryo. Our data reveal that Cnn and PLP directly interact at two defined sites to coordinate the cell cycle–dependent rearrangement and scaffolding activity of the centrosome to permit normal centrosome organization, cell division, and embryonic viability.
Collapse
Affiliation(s)
- Dorothy A Lerit
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Holly A Jordan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - John S Poulton
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Carey J Fagerstrom
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Brian J Galletta
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Mark Peifer
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| |
Collapse
|
50
|
Abstract
Germ cells are the special cells in the body that undergo meiosis to generate gametes and subsequently entire new organisms after fertilization, a process that continues generation after generation. Recent studies have expanded our understanding of the factors and mechanisms that specify germ cell fate, including the partitioning of maternally supplied 'germ plasm', inheritance of epigenetic memory and expression of transcription factors crucial for primordial germ cell (PGC) development. Even after PGCs are specified, germline fate is labile and thus requires protective mechanisms, such as global transcriptional repression, chromatin state alteration and translation of only germline-appropriate transcripts. Findings from diverse species continue to provide insights into the shared and divergent needs of these special reproductive cells.
Collapse
Affiliation(s)
- Susan Strome
- Molecular, Cell &Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Dustin Updike
- Kathryn W. Davis Center for Regenerative Biology &Medicine, Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672, USA
| |
Collapse
|