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Kobayashi N, Nishikawa SI. Nuclear Fusion in Yeast and Plant Reproduction. PLANTS (BASEL, SWITZERLAND) 2023; 12:3608. [PMID: 37896071 PMCID: PMC10609895 DOI: 10.3390/plants12203608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/09/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023]
Abstract
Nuclear fusion is essential for the sexual reproduction of various organisms, including plants, animals, and fungi. During the life cycle of flowering plants, nuclear fusion occurs three times: once during female gametogenesis and twice during double fertilization, when two sperm cells fertilize the egg and the central cell. Haploid nuclei migrate in an actin filament-dependent manner to become in close contact and, then, two nuclei fuse. The nuclear fusion process in plant reproduction is achieved through sequential nuclear membrane fusion events. Recent molecular genetic analyses using Arabidopsis thaliana showed the conservation of nuclear membrane fusion machinery between plants and the budding yeast Saccharomyces cerevisiae. These include the heat-shock protein 70 in the endoplasmic reticulum and the conserved nuclear membrane proteins. Analyses of the A. thaliana mutants of these components show that the completion of the sperm nuclear fusion at fertilization is essential for proper embryo and endosperm development.
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Affiliation(s)
- Nanami Kobayashi
- Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan;
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2
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Zhan G, Guo J, Tian Y, Ji F, Bai X, Zhao J, Guo J, Kang Z. High-throughput RNA sequencing reveals differences between the transcriptomes of the five spore forms of Puccinia striiformis f. sp. tritici, the wheat stripe rust pathogen. STRESS BIOLOGY 2023; 3:29. [PMID: 37676525 PMCID: PMC10441873 DOI: 10.1007/s44154-023-00107-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 07/11/2023] [Indexed: 09/08/2023]
Abstract
The devastating wheat stripe (yellow) rust pathogen, Puccinia striiformis f. sp. tritici (Pst), is a macrocyclic and heteroecious fungus. Pst produces urediniospores and teliospores on its primary host, wheat, and pycniospores and aeciospores are produced on its alternate hosts, barberry (Berberis spp.) or mahonia (Mahonia spp.). Basidiospores are developed from teliospores and infect alternate hosts. These five spore forms play distinct roles in Pst infection, disease development, and fungal survival, etc. However, the specific genes and mechanisms underlying these functional differences are largely unknown. In this study, we performed, for the first time in rust fungi, the deep RNA sequencing to examine the transcriptomic shift among all five Pst spore forms. Among a total of 29,591 identified transcripts, 951 were specifically expressed in basidiospores, whereas 920, 761, 266, and 110 were specific for teliospores, pycniospores, aeciospores, and urediniospores, respectively. Additionally, transcriptomes of sexual spores, namely pycniospores and basidiospores, showed significant differences from those of asexual spores (urediniospores, teliospores, and aeciospores), and transcriptomes of urediniospores and aeciospores were more similar to each other than to the three other spore forms. Especially, the basidiospores and pycniospores which infected the berberis shows wide differences in the cell wall degrading-enzymes and mating and pheromone response genes. Besides, we also found that there are 6234 differential expressed genes between the urediniospores and pycniospores, while only have 3 genes have alternative splicing enents, suggesting that differential genes expression may make more contribution than AS. This comprehensive transcriptome profiling can substantially improve our understanding of the developmental biology of the wheat stripe rust fungus.
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Affiliation(s)
- Gangming Zhan
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China
| | - Jia Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China
| | - Yuan Tian
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, P.R. China
| | - Fan Ji
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China
| | - Xingxuan Bai
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China
| | - Jing Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China
| | - Jun Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
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Snell WJ. Uncovering an ancestral green ménage à trois: Contributions of Chlamydomonas to the discovery of a broadly conserved triad of plant fertilization proteins. CURRENT OPINION IN PLANT BIOLOGY 2022; 69:102275. [PMID: 36007296 PMCID: PMC9899528 DOI: 10.1016/j.pbi.2022.102275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/22/2022] [Accepted: 07/04/2022] [Indexed: 05/10/2023]
Abstract
During sexual reproduction in the unicellular green alga Chlamydomonas, gametes undergo the conserved cellular events that define fertilization across the tree of life. After initial ciliary adhesion, plus and minus gametes attach to each other at plasma membrane sites specialized for fusion, their bilayers merge, and cell coalescence into a quadri-ciliated cell signals for nuclear fusion. Recent findings show that these conserved cellular events are driven by 3 conserved protein families, FUS1/GEX2, HAP2/GCS1, and KAR5/GEX1. New results also show that species-specific recognition in Chlamydomonas activates the ancestral, viral-like fusogen HAP2 to drive fusion; that the conserved nuclear envelope fusion protein KAR5/GEX1 is also essential for nuclear fusion in Arabidopsis; and that heterodimerization of BELL-KNOX proteins signals for nuclear fusion in Chlamydomonas through early diverging land plants. This review outlines how Chlamydomonas's Janus-like position in evolution along with the ease of working with its gametes have revealed broadly conserved mechanisms.
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Affiliation(s)
- William J Snell
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
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Abstract
Gene expression divergence through evolutionary processes is thought to be important for achieving programmed development in multicellular organisms. To test this premise in filamentous fungi, we investigated transcriptional profiles of 3,942 single-copy orthologous genes (SCOGs) in five related sordariomycete species that have morphologically diverged in the formation of their flask-shaped perithecia. We compared expression of the SCOGs to inferred gene expression levels of the most recent common ancestor of the five species, ranking genes from their largest increases to smallest increases in expression during perithecial development in each of the five species. We found that a large proportion of the genes that exhibited evolved increases in gene expression were important for normal perithecial development in Fusarium graminearum. Many of these genes were previously uncharacterized, encoding hypothetical proteins without any known functional protein domains. Interestingly, the developmental stages during which aberrant knockout phenotypes appeared largely coincided with the elevated expression of the deleted genes. In addition, we identified novel genes that affected normal perithecial development in Magnaporthe oryzae and Neurospora crassa, which were functionally and transcriptionally diverged from the orthologous counterparts in F. graminearum. Furthermore, comparative analysis of developmental transcriptomes and phylostratigraphic analysis suggested that genes encoding hypothetical proteins are generally young and transcriptionally divergent between related species. This study provides tangible evidence of shifts in gene expression that led to acquisition of novel function of orthologous genes in each lineage and demonstrates that several genes with hypothetical function are crucial for shaping multicellular fruiting bodies. IMPORTANCE The fungal class Sordariomycetes includes numerous important plant and animal pathogens. It also provides model systems for studying fungal fruiting body development, as its members develop fruiting bodies with a few well-characterized tissue types on common growth media and have rich genomic resources that enable comparative and functional analyses. To understand transcriptional divergence of key developmental genes between five related sordariomycete fungi, we performed targeted knockouts of genes inferred to have evolved significant upward shifts in expression. We found that many previously uncharacterized genes play indispensable roles at different stages of fruiting body development, which have undergone transcriptional activation in specific lineages. These novel genes are predicted to be phylogenetically young and tend to be involved in lineage- or species-specific function. Transcriptional activation of genes with unknown function seems to be more frequent than ever thought, which may be crucial for rapid adaption to changing environments for successful sexual reproduction.
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Nishikawa SI, Yamaguchi Y, Suzuki C, Yabe A, Sato Y, Kurihara D, Sato Y, Susaki D, Higashiyama T, Maruyama D. Arabidopsis GEX1 Is a Nuclear Membrane Protein of Gametes Required for Nuclear Fusion During Reproduction. FRONTIERS IN PLANT SCIENCE 2020; 11:548032. [PMID: 33154760 PMCID: PMC7586128 DOI: 10.3389/fpls.2020.548032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 09/15/2020] [Indexed: 05/25/2023]
Abstract
During the life cycle of flowering plants, nuclear fusion, or karyogamy, occurs three times: once during female gametogenesis, when the two polar nuclei fuse in the central cell, and twice during double fertilization. In Arabidopsis thaliana, nuclear fusion events during sexual reproduction proceed without the breakdown of the nuclear envelope, indicating that nuclear membrane fusion is essential for the completion of this process. Arabidopsis gamete expressed 1 (GEX1) is a membrane protein that is conserved among plant species. GEX1 shares homology with the yeast karyogamy protein Kar5, which is primarily expressed in the nuclear membrane. The GEX1 family represents a putative karyogamy factor. Herein, we show that GEX1 is required for the nuclear fusion events in Arabidopsis reproduction. GEX1-deficient mature female gametophytes were found to contain two unfused polar nuclei in close proximity within the central cell. Electron microscopy showed that the outer membrane of the polar nuclei was connected via the endoplasmic reticulum, whereas the inner membrane remained unfused. These results indicate that GEX1 is involved in polar nuclear membrane fusion following the fusion of the outer nuclear membrane. Furthermore, sperm nuclear fusion events were defective in the fertilized egg and central cell following plasmogamy in the fertilization of gex1-1 female gametophytes by gex1-1 pollen. An analysis of GEX1 localization in the female gametophyte using a transgenic line expressing GFP-tagged GEX1 driven by the GEX1 promoter showed that GEX1 is a nuclear membrane protein in the egg and central cell. Time-lapse live-cell imaging showed that in developing female gametophytes, the nuclear GFP-GEX1 signal was first detectable in the central cell shortly before the polar nuclei came in close contact, and then in the egg cell. Thus, we suggest that the GEX1-family proteins are nuclear membrane proteins involved in karyogamy in the reproduction of eukaryotes including flowering plants.
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Affiliation(s)
| | - Yuki Yamaguchi
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Chiharu Suzuki
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Ayaka Yabe
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Yuzuru Sato
- Biology Program, Faculty of Science, Niigata University, Niigata, Japan
| | - Daisuke Kurihara
- Japan Science and Technology Agency, PRESTO, Nagoya, Japan
- Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan
| | - Yoshikatsu Sato
- Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Daichi Susaki
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
| | - Tetsuya Higashiyama
- Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
| | - Daisuke Maruyama
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
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Thibert-Plante X, Præbel K, Østbye K, Kahilainen KK, Amundsen PA, Gavrilets S. Using mathematical modelling to investigate the adaptive divergence of whitefish in Fennoscandia. Sci Rep 2020; 10:7394. [PMID: 32355195 PMCID: PMC7193591 DOI: 10.1038/s41598-020-63684-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 03/25/2020] [Indexed: 02/08/2023] Open
Abstract
Modern speciation theory has greatly benefited from a variety of simple mathematical models focusing on the conditions and patterns of speciation and diversification in the presence of gene flow. Unfortunately the application of general theoretical concepts and tools to specific ecological systems remains a challenge. Here we apply modeling tools to better understand adaptive divergence of whitefish during the postglacial period in lakes of northern Fennoscandia. These lakes harbor up to three different morphs associated with the three major lake habitats: littoral, pelagic, and profundal. Using large-scale individual-based simulations, we aim to identify factors required for in situ emergence of the pelagic and profundal morphs in lakes initially colonized by the littoral morph. The importance of some of the factors we identify and study - sufficiently large levels of initial genetic variation, size- and habitat-specific mating, sufficiently large carrying capacity of the new niche - is already well recognized. In addition, our model also points to two other factors that have been largely disregarded in theoretical studies: fitness-dependent dispersal and strong predation in the ancestral niche coupled with the lack of it in the new niche(s). We use our theoretical results to speculate about the process of diversification of whitefish in Fennoscandia and to identify potentially profitable directions for future empirical research.
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Affiliation(s)
| | - Kim Præbel
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, N-9037, Tromsø, Norway.
| | - Kjartan Østbye
- Inland Norway University of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Campus Evenstad, Anne Evenstadsvei 80, NO-2480, Koppang, Norway.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, NO-0316, Oslo, Norway
| | - Kimmo K Kahilainen
- Lammi Biological Station, University of Helsinki, Pääjärventie 320, FI-16900, Lammi, Finland
| | - Per-Arne Amundsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, N-9037, Tromsø, Norway
| | - Sergey Gavrilets
- Department of Ecology and Evolutionary Biology, Department of Mathematics, National Institute for Mathematical and Biological Synthesis (NIMBioS), Center for the Dynamics of Social Complexity (DySoC), University of Tennessee, Knoxville, TN, 37996, USA
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7
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Rahman M, Chang IY, Harned A, Maheshwari R, Amoateng K, Narayan K, Cohen-Fix O. C. elegans pronuclei fuse after fertilization through a novel membrane structure. J Cell Biol 2020; 219:e201909137. [PMID: 31834351 PMCID: PMC7041684 DOI: 10.1083/jcb.201909137] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 11/04/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022] Open
Abstract
After fertilization, parental genomes are enclosed in two separate pronuclei. In Caenorhabditis elegans, and possibly other organisms, when the two pronuclei first meet, the parental genomes are separated by four pronuclear membranes. To understand how these membranes are breached to allow merging of parental genomes we used focused ion beam scanning electron microscopy (FIB-SEM) to study the architecture of the pronuclear membranes at nanometer-scale resolution. We find that at metaphase, the interface between the two pronuclei is composed of two membranes perforated by fenestrations ranging from tens of nanometers to several microns in diameter. The parental chromosomes come in contact through one of the large fenestrations. Surrounding this fenestrated, two-membrane region is a novel membrane structure, a three-way sheet junction, where the four membranes of the two pronuclei fuse and become two. In the plk-1 mutant, where parental genomes fail to merge, these junctions are absent, suggesting that three-way sheet junctions are needed for formation of a diploid genome.
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Affiliation(s)
- Mohammad Rahman
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD
| | - Irene Y. Chang
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD
| | - Adam Harned
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD
| | - Richa Maheshwari
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD
| | - Kwabena Amoateng
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD
| | - Kedar Narayan
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD
| | - Orna Cohen-Fix
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD
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Bloomfield G. The molecular foundations of zygosis. Cell Mol Life Sci 2020; 77:323-330. [PMID: 31203379 PMCID: PMC11105095 DOI: 10.1007/s00018-019-03187-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/27/2019] [Accepted: 06/06/2019] [Indexed: 10/26/2022]
Abstract
Zygosis is the generation of new biological individuals by the sexual fusion of gamete cells. Our current understanding of eukaryotic phylogeny indicates that sex is ancestral to all extant eukaryotes. Although sexual development is extremely diverse, common molecular elements have been retained. HAP2-GCS1, a protein that promotes the fusion of gamete cell membranes that is related in structure to certain viral fusogens, is conserved in many eukaryotic lineages, even though gametes vary considerably in form and behaviour between species. Similarly, although zygotes have dramatically different forms and fates in different organisms, diverse eukaryotes share a common developmental programme in which homeodomain-containing transcription factors play a central role. These common mechanistic elements suggest possible common evolutionary histories that, if correct, would have profound implications for our understanding of eukaryogenesis.
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Hwang D, Wada S, Takahashi A, Urawa H, Kamei Y, Nishikawa SI. Development of a Heat-Inducible Gene Expression System Using Female Gametophytes of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2019; 60:2564-2572. [PMID: 31359050 DOI: 10.1093/pcp/pcz148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 07/22/2019] [Indexed: 05/13/2023]
Abstract
Female gametophyte (FG) is crucial for reproduction in flowering plants. Arabidopsis thaliana produces Polygonum-type FGs, which consist of an egg cell, two synergid cells, three antipodal cells and a central cell. Egg cell and central cell are the two female gametes that give rise to the embryo and surrounding endosperm, respectively, after fertilization. During the development of a FG, a single megaspore produced by meiosis undergoes three rounds of mitosis to produce an eight-nucleate cell. A seven-celled FG is formed after cellularization. The central cell initially contains two polar nuclei that fuse during female gametogenesis to form the secondary nucleus. In this study, we developed a gene induction system for analyzing the functions of various genes in developing Arabidopsis FGs. This system allows transgene expression in developing FGs using the heat-inducible Cre-loxP recombination system and FG-specific embryo sac 2 (ES2) promoter. Efficient gene induction was achieved in FGs by incubating flower buds and isolated pistils at 35�C for short periods of time (1-5 min). Gene induction was also induced in developing FGs by heat treatment of isolated ovules using the infrared laser-evoked gene operator (IR-LEGO) system. Expression of a dominant-negative mutant of Sad1/UNC84 (SUN) proteins in developing FGs using the gene induction system developed in this study caused defects in polar nuclear fusion, indicating the roles of SUN proteins in this process. This strategy represents a new tool for analyzing the functions of genes in FG development and FG functions.
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Affiliation(s)
- Dukhyun Hwang
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
- Department of Microbiology, College of Natural Sciences, Pukyoung National University, Busan, South Korea
| | - Satomi Wada
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Azusa Takahashi
- Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata, Japan
| | - Hiroko Urawa
- Department of Education, Gifu Shotokugakuen University, Gifu, Japan
| | - Yasuhiro Kamei
- Spectrography and Bioimaging Facility, National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Shuh-Ichi Nishikawa
- Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata, Japan
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Avilov SV, Aleksandrova N. Fluorescence protein complementation in microscopy: applications beyond detecting bi-molecular interactions. Methods Appl Fluoresc 2018; 7:012001. [DOI: 10.1088/2050-6120/aaef01] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Fu C, Heitman J. PRM1 and KAR5 function in cell-cell fusion and karyogamy to drive distinct bisexual and unisexual cycles in the Cryptococcus pathogenic species complex. PLoS Genet 2017; 13:e1007113. [PMID: 29176784 PMCID: PMC5720818 DOI: 10.1371/journal.pgen.1007113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 12/07/2017] [Accepted: 11/13/2017] [Indexed: 11/18/2022] Open
Abstract
Sexual reproduction is critical for successful evolution of eukaryotic organisms in adaptation to changing environments. In the opportunistic human fungal pathogens, the Cryptococcus pathogenic species complex, C. neoformans primarily undergoes bisexual reproduction, while C. deneoformans undergoes both unisexual and bisexual reproduction. During both unisexual and bisexual cycles, a common set of genetic circuits regulates a yeast-to-hyphal morphological transition, that produces either monokaryotic or dikaryotic hyphae. As such, both the unisexual and bisexual cycles can generate genotypic and phenotypic diversity de novo. Despite the similarities between these two cycles, genetic and morphological differences exist, such as the absence of an opposite mating-type partner and monokaryotic instead of dikaryotic hyphae during C. deneoformans unisexual cycle. To better understand the similarities and differences between these modes of sexual reproduction, we focused on two cellular processes involved in sexual reproduction: cell-cell fusion and karyogamy. We identified orthologs of the plasma membrane fusion protein Prm1 and the nuclear membrane fusion protein Kar5 in both Cryptococcus species, and demonstrated their conserved roles in cell fusion and karyogamy during C. deneoformans α-α unisexual reproduction and C. deneoformans and C. neoformans a-α bisexual reproduction. Notably, karyogamy occurs inside the basidum during bisexual reproduction in C. neoformans, but often occurs earlier following cell fusion during bisexual reproduction in C. deneoformans. Characterization of these two genes also showed that cell fusion is dispensable for solo unisexual reproduction in C. deneoformans. The blastospores produced along hyphae during C. deneoformans unisexual reproduction are diploid, suggesting that diploidization occurs early during hyphal development, possibly through either an endoreplication pathway or cell fusion-independent karyogamy events. Taken together, our findings suggest distinct mating mechanisms for unisexual and bisexual reproduction in Cryptococcus, exemplifying distinct evolutionary trajectories within this pathogenic species complex.
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Affiliation(s)
- Ci Fu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States of America
- * E-mail:
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12
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Smoyer CJ, Katta SS, Gardner JM, Stoltz L, McCroskey S, Bradford WD, McClain M, Smith SE, Slaughter BD, Unruh JR, Jaspersen SL. Analysis of membrane proteins localizing to the inner nuclear envelope in living cells. J Cell Biol 2016; 215:575-590. [PMID: 27831485 PMCID: PMC5119940 DOI: 10.1083/jcb.201607043] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 10/03/2016] [Accepted: 10/18/2016] [Indexed: 12/31/2022] Open
Abstract
Understanding the protein composition of the inner nuclear membrane (INM) is fundamental to elucidating its role in normal nuclear function and in disease; however, few tools exist to examine the INM in living cells, and the INM-specific proteome remains poorly characterized. Here, we adapted split green fluorescent protein (split-GFP) to systematically localize known and predicted integral membrane proteins in Saccharomyces cerevisiae to the INM as opposed to the outer nuclear membrane. Our data suggest that components of the endoplasmic reticulum (ER) as well as other organelles are able to access the INM, particularly if they contain a small extraluminal domain. By pairing split-GFP with fluorescence correlation spectroscopy, we compared the composition of complexes at the INM and ER, finding that at least one is unique: Sbh2, but not Sbh1, has access to the INM. Collectively, our work provides a comprehensive analysis of transmembrane protein localization to the INM and paves the way for further research into INM composition and function.
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Affiliation(s)
| | | | | | - Lynn Stoltz
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Scott McCroskey
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | | | | | - Sarah E Smith
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | | | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO 64110 .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160
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13
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Maruyama D, Ohtsu M, Higashiyama T. Cell fusion and nuclear fusion in plants. Semin Cell Dev Biol 2016; 60:127-135. [PMID: 27473789 DOI: 10.1016/j.semcdb.2016.07.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
Eukaryotic cells are surrounded by a plasma membrane and have a large nucleus containing the genomic DNA, which is enclosed by a nuclear envelope consisting of the outer and inner nuclear membranes. Although these membranes maintain the identity of cells, they sometimes fuse to each other, such as to produce a zygote during sexual reproduction or to give rise to other characteristically polyploid tissues. Recent studies have demonstrated that the mechanisms of plasma membrane or nuclear membrane fusion in plants are shared to some extent with those of yeasts and animals, despite the unique features of plant cells including thick cell walls and intercellular connections. Here, we summarize the key factors in the fusion of these membranes during plant reproduction, and also focus on "non-gametic cell fusion," which was thought to be rare in plant tissue, in which each cell is separated by a cell wall.
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Affiliation(s)
- Daisuke Maruyama
- Kihara Institute for Biological Research, Yokohama City University, 641-12 Maioka-cho, Totsuka-ku, Yokohama, Kanagawa 244-0813, Japan.
| | - Mina Ohtsu
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Tetsuya Higashiyama
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; JST ERATO Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
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14
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Meseroll RA, Cohen-Fix O. The Malleable Nature of the Budding Yeast Nuclear Envelope: Flares, Fusion, and Fenestrations. J Cell Physiol 2016; 231:2353-60. [PMID: 26909870 DOI: 10.1002/jcp.25355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 02/19/2016] [Indexed: 11/10/2022]
Abstract
In eukaryotes, the nuclear envelope (NE) physically separates nuclear components and activities from rest of the cell. The NE also provides rigidity to the nucleus and contributes to chromosome organization. At the same time, the NE is highly dynamic; it must change shape and rearrange its components during development and throughout the cell cycle, and its morphology can be altered in response to mutation and disease. Here we focus on the NE of budding yeast, Saccharomyces cerevisiae, which has several unique features: it remains intact throughout the cell cycle, expands symmetrically during interphase, elongates during mitosis and, expands asymmetrically during mitotic delay. Moreover, its NE is safely breached during mating and when large structures, such as nuclear pore complexes and the spindle pole body, are embedded into its double membrane. The budding yeast NE lacks lamins and yet the nucleus is capable of maintaining a spherical shape throughout interphase. Despite these eccentricities, studies of the budding yeast NE have uncovered interesting, and likely conserved, processes that contribute to NE dynamics. In particular, we discuss the processes that drive and enable NE expansion and the dramatic changes in the NE that lead to extensions and fenestrations. J. Cell. Physiol. 231: 2353-2360, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Rebecca A Meseroll
- The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Orna Cohen-Fix
- The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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15
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Hellberg T, Paßvogel L, Schulz KS, Klupp BG, Mettenleiter TC. Nuclear Egress of Herpesviruses: The Prototypic Vesicular Nucleocytoplasmic Transport. Adv Virus Res 2016; 94:81-140. [PMID: 26997591 DOI: 10.1016/bs.aivir.2015.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Herpesvirus particles mature in two different cellular compartments. While capsid assembly and packaging of the genomic linear double-stranded DNA occur in the nucleus, virion formation takes place in the cytoplasm by the addition of numerous tegument proteins as well as acquisition of the viral envelope by budding into cellular vesicles derived from the trans-Golgi network containing virally encoded glycoproteins. To gain access to the final maturation compartment, herpesvirus nucleocapsids have to cross a formidable barrier, the nuclear envelope (NE). Since the ca. 120 nm diameter capsids are unable to traverse via nuclear pores, herpesviruses employ a vesicular transport through both leaflets of the NE. This process involves proteins which support local dissolution of the nuclear lamina to allow access of capsids to the inner nuclear membrane (INM), drive vesicle formation from the INM and mediate inclusion of the capsid as well as scission of the capsid-containing vesicle (also designated as "primary virion"). Fusion of the vesicle membrane (i.e., the "primary envelope") with the outer nuclear membrane subsequently results in release of the nucleocapsid into the cytoplasm for continuing virion morphogenesis. While this process has long been thought to be unique for herpesviruses, a similar pathway for nuclear egress of macromolecular complexes has recently been observed in Drosophila. Thus, herpesviruses may have coopted a hitherto unrecognized cellular mechanism of vesicle-mediated nucleocytoplasmic transport. This could have far reaching consequences for our understanding of cellular functions as again unraveled by the study of viruses.
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Affiliation(s)
- Teresa Hellberg
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Lars Paßvogel
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina S Schulz
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Barbara G Klupp
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
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16
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Sec66-Dependent Regulation of Yeast Spindle-Pole Body Duplication Through Pom152. Genetics 2015; 201:1479-95. [PMID: 26510791 PMCID: PMC4676539 DOI: 10.1534/genetics.115.178012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 10/23/2015] [Indexed: 02/06/2023] Open
Abstract
In closed mitotic systems such as Saccharomyces cerevisiae, the nuclear envelope (NE) does not break down during mitosis, so microtubule-organizing centers such as the spindle-pole body (SPB) must be inserted into the NE to facilitate bipolar spindle formation and chromosome segregation. The mechanism of SPB insertion has been linked to NE insertion of nuclear pore complexes (NPCs) through a series of genetic and physical interactions between NPCs and SPB components. To identify new genes involved in SPB duplication and NE insertion, we carried out genome-wide screens for suppressors of deletion alleles of SPB components, including Mps3 and Mps2. In addition to the nucleoporins POM152 and POM34, we found that elimination of SEC66/SEC71/KAR7 suppressed lethality of cells lacking MPS2 or MPS3. Sec66 is a nonessential subunit of the Sec63 complex that functions together with the Sec61 complex in import of proteins into the endoplasmic reticulum (ER). Cells lacking Sec66 have reduced levels of Pom152 protein but not Pom34 or Ndc1, a shared component of the NPC and SPB. The fact that Sec66 but not other subunits of the ER translocon bypass deletion mutants in SPB genes suggests a specific role for Sec66 in the control of Pom152 levels. Based on the observation that sec66∆ does not affect the distribution of Ndc1 on the NE or Ndc1 binding to the SPB, we propose that Sec66-mediated regulation of Pom152 plays an NPC-independent role in the control of SPB duplication.
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17
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Santos-Aberturas J, Dörr M, Waldo GS, Bornscheuer UT. In-Depth High-Throughput Screening of Protein Engineering Libraries by Split-GFP Direct Crude Cell Extract Data Normalization. ACTA ACUST UNITED AC 2015; 22:1406-14. [PMID: 26441043 DOI: 10.1016/j.chembiol.2015.08.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/08/2015] [Accepted: 08/13/2015] [Indexed: 12/29/2022]
Abstract
Here, we report a widely and generally applicable strategy to obtain reliable information in high-throughput protein screenings of enzyme mutant libraries. The method is based on the usage of the split-GFP technology for the normalization of the expression level of each individual protein variant combined with activity measurements, thus resolving the important problems associated with the different solubility of each mutant and allowing the detection of previously invisible variants. The small size of the employed protein tag (16 amino acids) required for the reconstitution of the GFP fluorescence reduces possible interferences such as enzyme activity variations or solubility disturbances to a minimum. Specific enzyme activity measurements without purification, in situ soluble protein expression monitoring, and data normalization are the powerful outputs of this methodology, thus enabling the accurate identification of improved protein variants during high-throughput screening by substantially reducing the occurrence of false negatives and false positives.
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Affiliation(s)
- Javier Santos-Aberturas
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix Hausdorff-Str. 4, 17487 Greifswald, Germany.
| | - Mark Dörr
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix Hausdorff-Str. 4, 17487 Greifswald, Germany.
| | - Geoffrey S Waldo
- Bioscience Division, Los Alamos National Laboratory, MS M888, Los Alamos, NM 87545, USA
| | - Uwe T Bornscheuer
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix Hausdorff-Str. 4, 17487 Greifswald, Germany
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