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Rawat SS, Laxmi A. Sugar signals pedal the cell cycle! FRONTIERS IN PLANT SCIENCE 2024; 15:1354561. [PMID: 38562561 PMCID: PMC10982403 DOI: 10.3389/fpls.2024.1354561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 02/19/2024] [Indexed: 04/04/2024]
Abstract
Cell cycle involves the sequential and reiterative progression of important events leading to cell division. Progression through a specific phase of the cell cycle is under the control of various factors. Since the cell cycle in multicellular eukaryotes responds to multiple extracellular mitogenic cues, its study in higher forms of life becomes all the more important. One such factor regulating cell cycle progression in plants is sugar signalling. Because the growth of organs depends on both cell growth and proliferation, sugars sensing and signalling are key control points linking sugar perception to regulation of downstream factors which facilitate these key developmental transitions. However, the basis of cell cycle control via sugars is intricate and demands exploration. This review deals with the information on sugar and TOR-SnRK1 signalling and how they manoeuvre various events of the cell cycle to ensure proper growth and development.
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Affiliation(s)
| | - Ashverya Laxmi
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
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2
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Sears RG, Rigoulot SB, Occhialini A, Morgan B, Kakeshpour T, Brabazon H, Barnes CN, Seaberry EM, Jacobs B, Brown C, Yang Y, Schimel TM, Lenaghan SC, Neal Stewart C. Engineered gamma radiation phytosensors for environmental monitoring. PLANT BIOTECHNOLOGY JOURNAL 2023; 21:1745-1756. [PMID: 37224108 PMCID: PMC10440981 DOI: 10.1111/pbi.14072] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/13/2023] [Accepted: 04/24/2023] [Indexed: 05/26/2023]
Abstract
Nuclear energy, already a practical solution for supplying energy on a scale similar to fossil fuels, will likely increase its footprint over the next several decades to meet current climate goals. Gamma radiation is produced during fission in existing nuclear reactors and thus the need to detect leakage from nuclear plants, and effects of such leakage on ecosystems will likely also increase. At present, gamma radiation is detected using mechanical sensors that have several drawbacks, including: (i) limited availability; (ii) reliance on power supply; and (iii) requirement of human presence in dangerous areas. To overcome these limitations, we have developed a plant biosensor (phytosensor) to detect low-dose ionizing radiation. The system utilizes synthetic biology to engineer a dosimetric switch into potato utilizing the plant's native DNA damage response (DDR) machinery to produce a fluorescent output. In this work, the radiation phytosensor was shown to respond to a wide range of gamma radiation exposure (10-80 Grey) producing a reporter signal that was detectable at >3 m. Further, a pressure test of the top radiation phytosensor in a complex mesocosm demonstrated full function of the system in a 'real world' scenario.
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Affiliation(s)
- Robert G. Sears
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Stephen B. Rigoulot
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Alessandro Occhialini
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
- Department of Food ScienceThe University of TennesseeKnoxvilleTennesseeUSA
| | - Britany Morgan
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Tayebeh Kakeshpour
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Holly Brabazon
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Caitlin N. Barnes
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Erin M. Seaberry
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Brianna Jacobs
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Chandler Brown
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Yongil Yang
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
| | - Tayler M. Schimel
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
- Department of Food ScienceThe University of TennesseeKnoxvilleTennesseeUSA
| | - Scott C. Lenaghan
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
- Department of Food ScienceThe University of TennesseeKnoxvilleTennesseeUSA
| | - C. Neal Stewart
- Department of Plant SciencesThe University of TennesseeKnoxvilleTennesseeUSA
- Center for Agricultural Synthetic BiologyThe University of Tennessee, KnoxvilleKnoxvilleTennesseeUSA
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3
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Zhao P, Zhang C, Song Y, Xu X, Wang J, Wang J, Zheng T, Lin Y, Lai Z. Genome-wide identification, expression and functional analysis of the core cell cycle gene family during the early somatic embryogenesis of Dimocarpus longan Lour. Gene 2022; 821:146286. [PMID: 35176425 DOI: 10.1016/j.gene.2022.146286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 12/29/2021] [Accepted: 02/03/2022] [Indexed: 11/04/2022]
Abstract
Core cell cycle genes (CCCs) are essential regulators of cell cycle operation. In this study, a total of 69 CCCs family members, including 37 CYCs, 20 CDKs, five E2F/DPs, three KRPs, two RBs, one CKS and one Wee1, were identified from the longan genome. Phylogenetic and motifs analysis showed the evolutionary conservation of CCCs. Transcriptome dataset showed that CCCs had various expression patterns during longan early somatic embryogenesis (SE). Either CKS or CYCD3;2 silencing increased the expression of RB-E2F pathway genes, and the silencing of CYCD3;2 might induce the process of apoptosis in longan embryogenic callus (EC) cells. In addition, The qRT-PCR results showed that the expression levels of CDKG2, CYCD3;2, CYCT1;2, CKS and KRP1 were elevated by ABA, 2,4-D and PEG4000 treatments, while CDKG2 and CYCT1;2 were inhibited by NaCl treatment. In conclusion, our study provided valuable information for understanding the characterization and biological functions of longan CCCs.
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Affiliation(s)
- Pengcheng Zhao
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Chunyu Zhang
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yuyang Song
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaoqiong Xu
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jinyi Wang
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jinhao Wang
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Tianyi Zheng
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yuling Lin
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zhongxiong Lai
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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Hydroxyurea and Caffeine Impact pRb-like Protein-Dependent Chromatin Architecture Profiles in Interphase Cells of Vicia faba. Int J Mol Sci 2021; 22:ijms22094572. [PMID: 33925461 PMCID: PMC8123844 DOI: 10.3390/ijms22094572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/06/2021] [Accepted: 04/23/2021] [Indexed: 01/04/2023] Open
Abstract
The survival of cells depends on their ability to replicate correctly genetic material. Cells exposed to replication stress can experience a number of problems that may lead to deregulated proliferation, the development of cancer, and/or programmed cell death. In this article, we have induced prolonged replication arrest via hydroxyurea (HU) treatment and also premature chromosome condensation (PCC) by co-treatment with HU and caffeine (CF) in the root meristem cells of Vicia faba. We have analyzed the changes in the activities of retinoblastoma-like protein (RbS807/811ph). Results obtained from the immunocytochemical detection of RbS807/811ph allowed us to distinguish five unique activity profiles of pRb. We have also performed detailed 3D modeling using Blender 2.9.1., based on the original data and some final conclusions. 3D models helped us to visualize better the events occurring within the nuclei and acted as a high-resolution aid for presenting the results. We have found that, despite the decrease in pRb activity, its activity profiles were mostly intact and clearly recognizable, with some local alterations that may correspond to the increased demand in transcriptional activity. Our findings suggest that Vicia faba’s ability to withstand harsh environments may come from its well-developed and highly effective response to replication stress.
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Banerjee G, Singh D, Sinha AK. Plant cell cycle regulators: Mitogen-activated protein kinase, a new regulating switch? PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 301:110660. [PMID: 33218628 DOI: 10.1016/j.plantsci.2020.110660] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/25/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Cell cycle is essential for the maintenance of genetic material and continuity of a species. Its regulation involves a complex interplay between multiple proteins with diverse molecular functions such as the kinases, transcription factors, proteases and phosphatases. Every step of this cycle requires a certain combination of these protein regulators which paves the way for the next stage. It is now evident that plants have their own unique features in the context of cell cycle regulation. Cell cycle in plants is not only necessary for maintenance of its physio-morphological parameter but it also regulates traits important for mankind like grain or fruit size. This makes it even more important to understand how plants regulate its cell cycle amidst various a/biotic stresses it is subjected to during its lifetime. The association of MAPK signaling pathways with every major developmental and stress response pathways in plants raises the question of its potential role in cell cycle regulation. There are number of cell cycle regulating proteins with putative sites for MAPK phosphorylation. The MAPK signaling pathway may directly or in a parallel pathway regulate the plant cell cycle. Unraveling the role of MAPK in cell cycle will open up new arenas to explore.
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Affiliation(s)
- Gopal Banerjee
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Dhanraj Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Alok Krishna Sinha
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India.
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Desvoyes B, Gutierrez C. Roles of plant retinoblastoma protein: cell cycle and beyond. EMBO J 2020; 39:e105802. [PMID: 32865261 PMCID: PMC7527812 DOI: 10.15252/embj.2020105802] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/16/2020] [Accepted: 08/06/2020] [Indexed: 12/16/2022] Open
Abstract
The human retinoblastoma (RB1) protein is a tumor suppressor that negatively regulates cell cycle progression through its interaction with members of the E2F/DP family of transcription factors. However, RB-related (RBR) proteins are an early acquisition during eukaryote evolution present in plant lineages, including unicellular algae, ancient plants (ferns, lycophytes, liverworts, mosses), gymnosperms, and angiosperms. The main RBR protein domains and interactions with E2Fs are conserved in all eukaryotes and not only regulate the G1/S transition but also the G2/M transition, as part of DREAM complexes. RBR proteins are also important for asymmetric cell division, stem cell maintenance, and the DNA damage response (DDR). RBR proteins play crucial roles at every developmental phase transition, in association with chromatin factors, as well as during the reproductive phase during female and male gametes production and embryo development. Here, we review the processes where plant RBR proteins play a role and discuss possible avenues of research to obtain a full picture of the multifunctional roles of RBR for plant life.
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Jones AR, Band LR, Murray JAH. Double or Nothing? Cell Division and Cell Size Control. TRENDS IN PLANT SCIENCE 2019; 24:1083-1093. [PMID: 31630972 DOI: 10.1016/j.tplants.2019.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 08/08/2019] [Accepted: 09/06/2019] [Indexed: 06/10/2023]
Abstract
Size is a fundamental property that must be tightly regulated to ensure that cells and tissues function efficiently. Dynamic size control allows unicellular organisms to adapt to environmental changes, but cell size is also integral to multicellular development, affecting tissue size and structure. Despite clear evidence for homeostatic cell size maintenance, we are only now beginning to understand cell size regulation in the actively dividing meristematic tissues of higher plants. We discuss here how coupled advances in live cell imaging and modelling are uncovering dynamic mechanisms for size control mediated at the cellular level. We argue that integrated models of cell growth and division will be necessary to predict cell size and fully understand multicellular growth and development.
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Affiliation(s)
- Angharad R Jones
- Cardiff School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK.
| | - Leah R Band
- Division of Plant and Crop Science, School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK; Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - James A H Murray
- Cardiff School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
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Genome-Wide Analysis of the D-type Cyclin Gene Family Reveals Differential Expression Patterns and Stem Development in the Woody Plant Prunus mume. FORESTS 2019. [DOI: 10.3390/f10020147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cyclins, a prominent class of cell division regulators, play an extremely important role in plant growth and development. D-type cyclins (CYCDs) are the rate-limiting components of the G1 phase. In plants, studies of CYCDs are mainly concerned with herbaceous plants, yet little information is available about these genes in perennial woody plants, especially ornamental plants. Here, twelve Prunus mume CYCD (PmCYCDs) genes are identified and characterized. The PmCYCDs were named on the basis of orthologues in Arabidopsis thaliana and Oryza sativa. Gene structure and conserved domains of each subgroup CYCDs was similar to that of their orthologues in A. thaliana and O. sativa. However, PmCYCDs exhibited different tissue-specific expression patterns in root, stem, leaf, bud, and fruit organs. The results of qRT-PCR showed that all PmCYCDs, except PmCYCD5;2 and PmCYCD7;1, were primarily highly expressed in leaf buds, shoots, and stems. In addition, the transcript levels of PmCYCD genes were analyzed in roots under different treatments, including exogenous applications of NAA, 6-BA, GA3, ABA, and sucrose. Interestingly, although PmCYCDs were induced by sucrose, the extent of gene induction among PmCYCD subgroups varied. The induction of PmCYCD1;2 by hormones depended on the presence of sucrose. PmCYCD3;1 was stimulated by NAA, and induction was strengthened when sugar and hormones were applied together. Taken together, our study demonstrates that PmCYCDs are functional in plant stem development and provides a basis for selecting members of the cyclin gene family as candidate genes for ornamental plant breeding.
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Gómez MS, Falcone Ferreyra ML, Sheridan ML, Casati P. Arabidopsis E2Fc is required for the DNA damage response under UV-B radiation epistatically over the microRNA396 and independently of E2Fe. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:749-764. [PMID: 30427087 DOI: 10.1111/tpj.14158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/25/2018] [Accepted: 11/02/2018] [Indexed: 05/17/2023]
Abstract
UV-B radiation inhibits plant growth, and this inhibition is, to a certain extent, regulated by miR396-mediated repression of Growth Regulating Transcription factors (GRFs). Moreover, E2Fe transcription factor also modulates Arabidopsis leaf growth. Here, we provide evidence that, at UV-B intensities that induce DNA damage, E2Fc participates in the inhibition of cell proliferation. We demonstrate that E2Fc-deficient plants show a lower inhibition of leaf size under UV-B conditions that damage DNA, decreased cell death after exposure and altered SOG1 and ATR expression. Interestingly, the previously reported participation of E2Fe in UV-B responses, which is a transcriptional target of E2Fc, is independent and different from that described for E2Fc. Conversely, we here demonstrate that E2Fc has an epistatic role over the miR396 pathway under UV-B conditions. Finally, we show that inhibition of cell proliferation by UV-B is independent of the regulation of class II TCP transcription factors. Together, our results demonstrate that E2Fc is required for miR396 activity on cell proliferation under UV-B, and that its role is independent of E2Fe, probably modulating DNA damage responses through the regulation of SOG1 and ATR transcript levels.
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Affiliation(s)
- María S Gómez
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - María L Falcone Ferreyra
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - María L Sheridan
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Paula Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
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Weimer AK, Matos JL, Sharma N, Patell F, Murray JAH, Dewitte W, Bergmann DC. Lineage- and stage-specific expressed CYCD7;1 coordinates the single symmetric division that creates stomatal guard cells. Development 2018; 145:dev.160671. [PMID: 29467245 DOI: 10.1242/dev.160671] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/13/2018] [Indexed: 11/20/2022]
Abstract
Plants, with cells fixed in place by rigid walls, often utilize spatial and temporally distinct cell division programs to organize and maintain organs. This leads to the question of how developmental regulators interact with the cell cycle machinery to link cell division events with particular developmental trajectories. In Arabidopsis leaves, the development of stomata, two-celled epidermal valves that mediate plant-atmosphere gas exchange, relies on a series of oriented stem cell-like asymmetric divisions followed by a single symmetric division. The stomatal lineage is embedded in a tissue in which other cells transition from proliferation to postmitotic differentiation earlier, necessitating stomatal lineage-specific factors to prolong competence to divide. We show that the D-type cyclin, CYCD7;1, is specifically expressed just prior to the symmetric guard cell-forming division, and that it is limiting for this division. Further, we find that CYCD7;1 is capable of promoting divisions in multiple contexts, likely through RBR1-dependent promotion of the G1/S transition, but that CYCD7;1 is regulated at the transcriptional level by cell type-specific transcription factors that confine its expression to the appropriate developmental window.
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Affiliation(s)
- Annika K Weimer
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Juliana L Matos
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Nidhi Sharma
- Howard Hughes Medical Institute (HHMI), Stanford University, Stanford, CA 94305, USA
| | - Farah Patell
- Cardiff School of Bioscience, Cardiff University, Cardiff CF10 3AX, UK.,Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, UK
| | - James A H Murray
- Cardiff School of Bioscience, Cardiff University, Cardiff CF10 3AX, UK.,Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, UK
| | - Walter Dewitte
- Cardiff School of Bioscience, Cardiff University, Cardiff CF10 3AX, UK.,Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, UK
| | - Dominique C Bergmann
- Department of Biology, Stanford University, Stanford, CA 94305, USA .,Howard Hughes Medical Institute (HHMI), Stanford University, Stanford, CA 94305, USA
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11
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Cell-size dependent progression of the cell cycle creates homeostasis and flexibility of plant cell size. Nat Commun 2017; 8:15060. [PMID: 28447614 PMCID: PMC5414177 DOI: 10.1038/ncomms15060] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 02/23/2017] [Indexed: 11/09/2022] Open
Abstract
Mean cell size at division is generally constant for specific conditions and cell types, but the mechanisms coupling cell growth and cell cycle control with cell size regulation are poorly understood in intact tissues. Here we show that the continuously dividing fields of cells within the shoot apical meristem of Arabidopsis show dynamic regulation of mean cell size dependent on developmental stage, genotype and environmental signals. We show cell size at division and cell cycle length is effectively predicted using a two-stage cell cycle model linking cell growth and two sequential cyclin dependent kinase (CDK) activities, and experimental results concur in showing that progression through both G1/S and G2/M is size dependent. This work shows that cell-autonomous co-ordination of cell growth and cell division previously observed in unicellular organisms also exists in intact plant tissues, and that cell size may be an emergent rather than directly determined property of cells.
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García-Cruz KV, García-Ponce B, Garay-Arroyo A, Sanchez MDLP, Ugartechea-Chirino Y, Desvoyes B, Pacheco-Escobedo MA, Tapia-López R, Ransom-Rodríguez I, Gutierrez C, Alvarez-Buylla ER. The MADS-box XAANTAL1 increases proliferation at the Arabidopsis root stem-cell niche and participates in transition to differentiation by regulating cell-cycle components. ANNALS OF BOTANY 2016; 118:787-796. [PMID: 27474508 PMCID: PMC5055633 DOI: 10.1093/aob/mcw126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 05/16/2016] [Indexed: 05/08/2023]
Abstract
Background Morphogenesis depends on the concerted modulation of cell proliferation and differentiation. Such modulation is dynamically adjusted in response to various external and internal signals via complex transcriptional regulatory networks that mediate between such signals and regulation of cell-cycle and cellular responses (proliferation, growth, differentiation). In plants, which are sessile, the proliferation/differentiation balance is plastically adjusted during their life cycle and transcriptional networks are important in this process. MADS-box genes are key developmental regulators in eukaryotes, but their role in cell proliferation and differentiation modulation in plants remains poorly studied. Methods We characterize the XAL1 loss-of-function xal1-2 allele and overexpression lines using quantitative cellular and cytometry analyses to explore its role in cell cycle, proliferation, stem-cell patterning and transition to differentiation. We used quantitative PCR and cellular markers to explore if XAL1 regulates cell-cycle components and PLETHORA1 (PLT1) gene expression, as well as confocal microscopy to analyse stem-cell niche organization. Key Results We previously showed that XAANTAL1 (XAL1/AGL12) is necessary for Arabidopsis root development as a promoter of cell proliferation in the root apical meristem. Here, we demonstrate that XAL1 positively regulates the expression of PLT1 and important components of the cell cycle: CYCD3;1, CYCA2;3, CYCB1;1, CDKB1;1 and CDT1a. In addition, we show that xal1-2 mutant plants have a premature transition to differentiation with root hairs appearing closer to the root tip, while endoreplication in these plants is partially compromised. Coincidently, the final size of cortex cells in the mutant is shorter than wild-type cells. Finally, XAL1 overexpression-lines corroborate that this transcription factor is able to promote cell proliferation at the stem-cell niche. Conclusion XAL1 seems to be an important component of the networks that modulate cell proliferation/differentiation transition and stem-cell proliferation during Arabidopsis root development; it also regulates several cell-cycle components.
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Affiliation(s)
- Karla V. García-Cruz
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - Berenice García-Ponce
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - Adriana Garay-Arroyo
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - María De La Paz Sanchez
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - Yamel Ugartechea-Chirino
- Centro de Investigación en Dinámica Celular, Facultad de Ciencias, Universidad Autónoma de Morelos, Av. Universidad 1001, Col Chamilpa, Cuernavaca, Morelos, 62209, México
| | - Bénédicte Desvoyes
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Mario A. Pacheco-Escobedo
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - Rosalinda Tapia-López
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - Ivan Ransom-Rodríguez
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
| | - Crisanto Gutierrez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Elena R. Alvarez-Buylla
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad 3000, Coyoacán, México D.F. 04510, México
- *For correspondence. E-mail
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de Jonge J, Kodde J, Severing EI, Bonnema G, Angenent GC, Immink RGH, Groot SPC. Low Temperature Affects Stem Cell Maintenance in Brassica oleracea Seedlings. FRONTIERS IN PLANT SCIENCE 2016; 7:800. [PMID: 27375654 PMCID: PMC4896912 DOI: 10.3389/fpls.2016.00800] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/22/2016] [Indexed: 05/11/2023]
Abstract
Most of the above ground tissues in higher plants originate from stem cells located in the shoot apical meristem (SAM). Several plant species can suffer from spontaneous stem cell arrest resulting in lack of further shoot development. In Brassica oleracea this SAM arrest is known as blindness and occurs in an unpredictable manner leading to considerable economic losses for plant raisers and farmers. Detailed analyses of seedlings showed that stem cell arrest is triggered by low temperatures during germination. To induce this arrest reproducibly and to study the effect of the environment, an assay was developed. The role of genetic variation on the susceptibility to develop blind seedlings was analyzed by a quantitative genetic mapping approach, using seeds from a double haploid population from a cross between broccoli and Chinese kale, produced at three locations. The analysis revealed, besides an effect of the seed production location, a region on linkage group C3 associated with blindness sensitivity. A subsequent dynamic genome-wide transcriptome analysis resulted in the identification of around 3000 differentially expressed genes early after blindness induction. A large number of cell cycle genes were en masse induced early during the development of blindness, whereas shortly after, all were down-regulated. This miss-regulation of core cell cycle genes is accompanied with a strong reduction of cells reaching the DNA replication phase. From the differentially expressed genes, 90 were located in the QTL region C3. Among them are two genes belonging to the MINICHROMOSOMAL MAINTENANCE gene family, known to be involved in DNA replication, a RETINOBLASTOMA-RELATED gene, a key regulator for cell cycle initiation, and several MutS homologs genes, involved in DNA repair. These genes are potential candidates for being involved in the development of blindness in Brassica oleracea sensitive genotypes.
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Affiliation(s)
- Jennifer de Jonge
- Bioscience, Plant Research International, Wageningen University and Research CenterWageningen, Netherlands
- Laboratory of Molecular Biology, Wageningen University, Wageningen University and Research CenterWageningen, Netherlands
| | - Jan Kodde
- Bioscience, Plant Research International, Wageningen University and Research CenterWageningen, Netherlands
| | - Edouard I. Severing
- Bioscience, Plant Research International, Wageningen University and Research CenterWageningen, Netherlands
| | - Guusje Bonnema
- Wageningen UR Plant Breeding, Wageningen University, Wageningen University and Research CenterWageningen, Netherlands
| | - Gerco C. Angenent
- Bioscience, Plant Research International, Wageningen University and Research CenterWageningen, Netherlands
- Laboratory of Molecular Biology, Wageningen University, Wageningen University and Research CenterWageningen, Netherlands
| | - Richard G. H. Immink
- Bioscience, Plant Research International, Wageningen University and Research CenterWageningen, Netherlands
- Laboratory of Molecular Biology, Wageningen University, Wageningen University and Research CenterWageningen, Netherlands
| | - Steven P. C. Groot
- Bioscience, Plant Research International, Wageningen University and Research CenterWageningen, Netherlands
- *Correspondence: Steven P. C. Groot,
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14
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Polyn S, Willems A, De Veylder L. Cell cycle entry, maintenance, and exit during plant development. CURRENT OPINION IN PLANT BIOLOGY 2015; 23:1-7. [PMID: 25449720 DOI: 10.1016/j.pbi.2014.09.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 09/22/2014] [Accepted: 09/30/2014] [Indexed: 05/24/2023]
Abstract
Growth and development of plants are driven by the continuous production of new cells at the meristems; hence, it is of pivotal importance for plants to precisely regulate the timing and extent of cell proliferation. Although over the past decades the molecular components underlying cell cycle progression have been the subject of intensive research, knowledge remains scarce on how the various elements connect with developmental pathways. Recently, advances have been made that link cell cycle entry with nutrient availability, cell division maintenance with stem cell organization, and cell cycle exit with reactive oxygen species and developmental programs.
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Affiliation(s)
- Stefanie Polyn
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium
| | - Alex Willems
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium
| | - Lieven De Veylder
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium.
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15
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Abstract
This review, written from a personal perspective, traces firstly the development of plant cell cycle research from the 1970s onwards, with some focus on the work of the author and of Dr Dennis Francis. Secondly there is a discussion of the support for and discussion of plant cell cycle research in the SEB, especially through the activities of the Cell Cycle Group within the Society's Cell Biology Section. In the main part of the review, selected aspects of DNA replication that have of been of special interest to the author are discussed. These are DNA polymerases and associated proteins, pre-replication events, regulation of enzymes and other proteins, nature and activation of DNA replication origins, and DNA endoreduplication. For all these topics, there is mention of the author's own work, followed by a brief synthesis of current understanding and a look to possible future developments.
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Affiliation(s)
- John Bryant
- School of Biosciences, CLES, University of Exeter, Exeter EX4 4PS, UK
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16
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Kuwabara A, Gruissem W. Arabidopsis RETINOBLASTOMA-RELATED and Polycomb group proteins: cooperation during plant cell differentiation and development. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2667-76. [PMID: 24638900 DOI: 10.1093/jxb/eru069] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
RETINOBLASTOMA (RB) is a tumour suppressor gene originally discovered in patients that develop eye tumours. The pRb protein is now well established as a key cell-cycle regulator which suppresses G1-S transition via interaction with E2F-DP complexes. pRb function is also required for a wide range of biological processes, including the regulation of stem-cell maintenance, cell differentiation, permanent cell-cycle exit, DNA repair, and genome stability. Such multifunctionality of pRb is thought to be facilitated through interactions with various binding partners in a context-dependent manner. Although the molecular network in which RB controls various biological processes is not fully understood, it has been found that pRb interacts with transcription factors and chromatin modifiers to either suppress or promote the expression of key genes during the switch from cell proliferation to differentiation. RETINOBLASTOMA-RELATED (RBR) is the plant orthologue of RB and is also known to negatively control the G1-S transition. Similar to its animal counterpart, plant RBR has various roles throughout plant development; however, much of its molecular functions outside of the G1-S transition are still unknown. One of the better-characterized molecular mechanisms is the cooperation of RBR with the Polycomb repressive complex 2 (PRC2) during plant-specific developmental events. This review summarizes the current understanding of this cooperation and focuses on the processes in Arabidopsis in which the RBR-PRC2 cooperation facilitates cell differentiation and developmental transitions.
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Affiliation(s)
- Asuka Kuwabara
- Department of Biology, ETH Zurich, Universitaetstrasse 2, 8092 Zurich, Switzerland
| | - Wilhelm Gruissem
- Department of Biology, ETH Zurich, Universitaetstrasse 2, 8092 Zurich, Switzerland
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17
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Choi CM, Gray WM, Mooney S, Hellmann H. Composition, roles, and regulation of cullin-based ubiquitin e3 ligases. THE ARABIDOPSIS BOOK 2014; 12:e0175. [PMID: 25505853 PMCID: PMC4262284 DOI: 10.1199/tab.0175] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Due to their sessile nature, plants depend on flexible regulatory systems that allow them to adequately regulate developmental and physiological processes in context with environmental cues. The ubiquitin proteasome pathway, which targets a great number of proteins for degradation, is cellular tool that provides the necessary flexibility to accomplish this task. Ubiquitin E3 ligases provide the needed specificity to the pathway by selectively binding to particular substrates and facilitating their ubiquitylation. The largest group of E3 ligases known in plants is represented by CULLIN-REALLY INTERESTING NEW GENE (RING) E3 ligases (CRLs). In recent years, a great amount of knowledge has been generated to reveal the critical roles of these enzymes across all aspects of plant life. This review provides an overview of the different classes of CRLs in plants, their specific complex compositions, the variety of biological processes they control, and the regulatory steps that can affect their activities.
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Affiliation(s)
| | | | | | - Hanjo Hellmann
- Washington State University, Pullman, Washington
- Address correspondence to
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18
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Magyar Z, Horváth B, Khan S, Mohammed B, Henriques R, De Veylder L, Bakó L, Scheres B, Bögre L. Arabidopsis E2FA stimulates proliferation and endocycle separately through RBR-bound and RBR-free complexes. EMBO J 2012; 31:1480-93. [PMID: 22307083 DOI: 10.1038/emboj.2012.13] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 01/09/2012] [Indexed: 12/16/2022] Open
Abstract
Post-embryonic growth in plants depends on the continuous supply of undifferentiated cells within meristems. Proliferating cells maintain their competence for division by active repression of differentiation and the associated endocycle entry. We show by upregulation and downregulation of E2FA that it is required for maintaining proliferation, as well as for endocycle entry. While E2FB-RBR1 (retinoblastoma-related protein 1) complexes are reduced after sucrose addition or at elevated CYCD3;1 levels, E2FA maintains a stable complex with RBR1 in proliferating cells. Chromatin immunoprecipitation shows that RBR1 binds in the proximity of E2F promoter elements in CCS52A1 and CSS52A2 genes, central regulators for the switch from proliferation to endocycles. Overexpression of a truncated E2FA mutant (E2FA(ΔRB)) lacking the RBR1-binding domain interferes with RBR1 recruitment to promoters through E2FA, leading to decreased meristem size in roots, premature cell expansion and hyperactivated endocycle in leaves. E2F target genes, including CCS52A1 and CCS52A2, are upregulated in E2FA(ΔRB) and e2fa knockout lines. These data suggest that E2FA in complex with RBR1 forms a repressor complex in proliferating cells to inhibit premature differentiation and endocycle entry. Thus, E2FA regulates organ growth via two distinct, sequentially operating pathways.
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Affiliation(s)
- Zoltán Magyar
- Royal Holloway, University of London, School of Biological Sciences, Centre for Systems and Synthetic Biology, Egham, UK.
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19
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Hirano H, Shinmyo A, Sekine M. Arabidopsis G1 cell cycle proteins undergo proteasome-dependent degradation during sucrose starvation. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:687-691. [PMID: 21444209 DOI: 10.1016/j.plaphy.2011.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 02/27/2011] [Indexed: 05/30/2023]
Abstract
Although sucrose availability is crucial for commitment to plant cell division during G1 phase, it has remained uncertain how protein levels of core cell cycle genes are regulated. We found that Arabidopsis retinoblastoma-related protein1 (AtRBR1) and three E2F proteins were degraded under limited sucrose conditions, while protein abundance increased in response to treatment with the proteasome inhibitor MG132. We conclude that Arabidopsis key cell cycle proteins are degraded in a proteasome-dependent manner during sucrose starvation in Arabidopsis suspension MM2d cells.
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Affiliation(s)
- Hiroto Hirano
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan
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20
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Johansson M, McWatters HG, Bakó L, Takata N, Gyula P, Hall A, Somers DE, Millar AJ, Eriksson ME. Partners in time: EARLY BIRD associates with ZEITLUPE and regulates the speed of the Arabidopsis clock. PLANT PHYSIOLOGY 2011; 155:2108-22. [PMID: 21300918 PMCID: PMC3091123 DOI: 10.1104/pp.110.167155] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 02/06/2011] [Indexed: 05/18/2023]
Abstract
The circadian clock of the model plant Arabidopsis (Arabidopsis thaliana) is made up of a complex series of interacting feedback loops whereby proteins regulate their own expression across day and night. early bird (ebi) is a circadian mutation that causes the clock to speed up: ebi plants have short circadian periods, early phase of clock gene expression, and are early flowering. We show that EBI associates with ZEITLUPE (ZTL), known to act in the plant clock as a posttranslational mediator of protein degradation. However, EBI is not degraded by its interaction with ZTL. Instead, ZTL counteracts the effect of EBI during the day and increases it at night, modulating the expression of key circadian components. The partnership of EBI with ZTL reveals a novel mechanism involved in controlling the complex transcription-translation feedback loops of the clock. This work highlights the importance of cross talk between the ubiquitination pathway and transcriptional control for regulation of the plant clock.
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21
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Olson BJ, Oberholzer M, Li Y, Zones JM, Kohli HS, Bisova K, Fang SC, Meisenhelder J, Hunter T, Umen JG. Regulation of the Chlamydomonas cell cycle by a stable, chromatin-associated retinoblastoma tumor suppressor complex. THE PLANT CELL 2010; 22:3331-47. [PMID: 20978220 PMCID: PMC2990127 DOI: 10.1105/tpc.110.076067] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 08/31/2010] [Accepted: 10/09/2010] [Indexed: 05/19/2023]
Abstract
We examined the cell cycle dynamics of the retinoblastoma (RB) protein complex in the unicellular alga Chlamydomonas reinhardtii that has single homologs for each subunit-RB, E2F, and DP. We found that Chlamydomonas RB (encoded by MAT3) is a cell cycle-regulated phosphoprotein, that E2F1-DP1 can bind to a consensus E2F site, and that all three proteins interact in vivo to form a complex that can be quantitatively immunopurified. Yeast two-hybrid assays revealed the formation of a ternary complex between MAT3, DP1, and E2F1 that requires a C-terminal motif in E2F1 analogous to the RB binding domain of plant and animal E2Fs. We examined the abundance of MAT3/RB and E2F1-DP1 in highly synchronous cultures and found that they are synthesized and remain stably associated throughout the cell cycle with no detectable fraction of free E2F1-DP1. Consistent with their stable association, MAT3/RB and DP1 are constitutively nuclear, and MAT3/RB does not require DP1-E2F1 for nuclear localization. In the nucleus, MAT3/RB remains bound to chromatin throughout the cell cycle, and its chromatin binding is mediated through E2F1-DP1. Together, our data show that E2F-DP complexes can regulate the cell cycle without dissociation of their RB-related subunit and that other changes may be sufficient to convert RB-E2F-DP from a cell cycle repressor to an activator.
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Affiliation(s)
- Bradley J.S.C. Olson
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Michael Oberholzer
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Yubing Li
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - James M. Zones
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Harjivan S. Kohli
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Katerina Bisova
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Su-Chiung Fang
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Jill Meisenhelder
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - James G. Umen
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
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22
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Positive regulation of minichromosome maintenance gene expression, DNA replication, and cell transformation by a plant retinoblastoma gene. Proc Natl Acad Sci U S A 2009; 106:4042-7. [PMID: 19234120 DOI: 10.1073/pnas.0813329106] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Retinoblastoma-related (RBR) genes inhibit the cell cycle primarily by repressing adenovirus E2 promoter binding factor (E2F) transcription factors, which drive the expression of numerous genes required for DNA synthesis and cell cycle progression. The RBR-E2F pathway is conserved in plants, but cereals such as maize are characterized by having a complex RBR gene family with at least 2 functionally distinct members, RBR1 and RBR3. Although RBR1 has a clear cell cycle inhibitory function, it is not known whether RBR3 has a positive or negative role. By uncoupling RBR3 from the negative regulation of RBR1 in cultured maize embryos through a combination of approaches, we demonstrate that RBR3 has a positive and critical role in the expression of E2F targets required for the initiation of DNA synthesis, DNA replication, and the efficiency with which transformed plants can be obtained. Titration of endogenous RBR3 activity through expression of a dominant-negative allele with a compromised pocket domain suggests that these RBR3 functions require an activity distinct from its pocket domain. Our results indicate a cell cycle pathway in maize, in which 2 RBR genes have specific and opposing functions. Thus, the paradigm that RBR genes are negative cell cycle regulators cannot be considered universal.
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23
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Hirano H, Harashima H, Shinmyo A, Sekine M. Arabidopsis RETINOBLASTOMA-RELATED PROTEIN 1 is involved in G1 phase cell cycle arrest caused by sucrose starvation. PLANT MOLECULAR BIOLOGY 2008; 66:259-75. [PMID: 18064404 DOI: 10.1007/s11103-007-9268-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Accepted: 11/18/2007] [Indexed: 05/14/2023]
Abstract
Although sucrose availability is crucial for commitment to plant cell division during G1 phase by controlling the expression of D-type cyclins, it has remained unclear how these factors mediate entry into the cell cycle. Here we show that Arabidopsis RETINOBLASTOMA-RELATED PROTEIN 1 (AtRBR1) is involved in G1-phase cell cycle arrest caused by sucrose starvation. We generated estrogen-inducible AtRBR1 RNA interference (RNAi) Arabidopsis suspension MM2d cells, and found that downregulation of AtRBR1 leads to a higher frequency of arrest in G2 phase, instead of G1-phase arrest in the uninduced control, after sucrose starvation. Synchronization experiments confirmed that downregulation of AtRBR1 leads to a prolonged G2 phase and delayed activation of G2/M marker genes. Downregulation of AtRBR1 also stimulated the activation of E2F-regulated genes when these genes were repressed in the uninduced cells under the limited sucrose conditions. We conclude that AtRBR1 is a key effector for the ability of sucrose to modulate progression from G1 phase.
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Affiliation(s)
- Hiroto Hirano
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan
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24
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Menges M, Pavesi G, Morandini P, Bögre L, Murray JAH. Genomic organization and evolutionary conservation of plant D-type cyclins. PLANT PHYSIOLOGY 2007; 145:1558-76. [PMID: 17951462 PMCID: PMC2151690 DOI: 10.1104/pp.107.104901] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Accepted: 10/06/2007] [Indexed: 05/21/2023]
Abstract
Plants contain more genes encoding core cell cycle regulators than other organisms but it is unclear whether these represent distinct functions. D-type cyclins (CYCD) play key roles in the G1-to-S-phase transition, and Arabidopsis (Arabidopsis thaliana) contains 10 CYCD genes in seven defined subgroups, six of which are conserved in rice (Oryza sativa). Here, we identify 22 CYCD genes in the poplar (Populus trichocarpa) genome and confirm that these six CYCD subgroups are conserved across higher plants, suggesting subgroup-specific functions. Different subgroups show gene number increases, with CYCD3 having three members in Arabidopsis, six in poplar, and a single representative in rice. All three species contain a single CYCD7 gene. Despite low overall sequence homology, we find remarkable conservation of intron/exon boundaries, because in most CYCD genes of plants and mammals, the first exon ends in the conserved cyclin signature. Only CYCD3 genes contain the complete cyclin box in a single exon, and this structure is conserved across angiosperms, again suggesting an early origin for the subgroup. The single CYCD gene of moss has a gene structure closely related to those of higher plants, sharing an identical exon/intron structure with several higher plant subgroups. However, green algae have CYCD genes structurally unrelated to higher plants. Conservation is also observed in the location of potential cyclin-dependent kinase phosphorylation sites within CYCD proteins. Subgroup structure is supported by conserved regulatory elements, particularly in the eudicot species, including conserved E2F regulatory sites within CYCD3 promoters. Global expression correlation analysis further supports distinct expression patterns for CYCD subgroups.
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Affiliation(s)
- Margit Menges
- Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
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25
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Kodama Y, Nagaya S, Shinmyo A, Kato K. Mapping and characterization of DNase I hypersensitive sites in Arabidopsis chromatin. PLANT & CELL PHYSIOLOGY 2007; 48:459-70. [PMID: 17283013 DOI: 10.1093/pcp/pcm017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Recent genome-wide analyses of yeast and human chromatin revealed the widespread prevalence of DNase I hypersensitive sites (DNase I HSs) at gene regulatory regions with possible roles in eukaryotic gene regulation. The presence of DNase I HSs in plants has been described for only a few genes, and we analyzed the chromatin structure of an 80 kb genomic region containing 30 variably expressed genes by DNase I sensitivity assay at 500 bp resolution in Arabidopsis. Distinct DNase I HSs were found at the 5' and/or 3' ends of most genes irrespective of their expression levels. Further analysis of well-characterized genes showed that the DNase I HSs occurred near cis-regulatory elements in the promoters of these genes. Upon transcriptional activation of a heat-inducible gene, the DNase I HS was extended into the vicinity of a cis-element and adjacent TATA element in the promoter. Concomitant with this change in DNase I HS, histones were acetylated, removed from the promoter, and a transcription activator bound to this cis-element. These results suggest that the DNase I HSs participate in the transcriptional regulation of Arabidopsis genes by enhancing the access of chromatin remodeling factors and/or transcription factors to their target sites as seen in yeast and human chromatin.
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Affiliation(s)
- Yuichi Kodama
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
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26
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Abstract
The basic components of the plant cell cycle are G1 (postmitotic interphase), S-phase (DNA synthesis phase), G2 (premitotic interphase) and mitosis/cytokinesis. Proliferating cells are phosphoregulated by cyclin-dependent protein kinases (CDKs). Plant D-type cyclins are sensors of the G0 to G1 transition, and are also important for G2/M. At G1/S, the S-phase transcription factor, E2F, is released from inhibitory retinoblastoma protein. Negative regulation of G1 events is through KRPs (Kip-related proteins). Plant S-phase genes are similar to animal ones, but timing of expression can be different (e.g. CDC6 at the start of S-phase) and functional evidence is limited. At G2/M, A-type and the unique B-type CDKs when bound to A, B and D cyclins, drive cells into division; they are negatively regulated by ICK1/2 and perhaps also by WEE1 kinase. In Arabidopsis, a putative CDC25 lacks a regulatory domain. Mitosis depends on correct temporal activity of CDKs, Aurora kinases and anaphase promotion complex; CDK-cyclin B activity beyond metaphase is catastrophic. Endoreduplication (re-replication of DNA in the absence of mitosis) is characterized by E2F expression and down-regulation of mitotic cyclins. Some cell size data support, whilst others negate, the idea of cell size having an impact on development.
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Affiliation(s)
- Dennis Francis
- School of Biosciences, Cardiff University, PO Box 915, Cardiff CF10 3TL, UK
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27
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Wyrzykowska J, Schorderet M, Pien S, Gruissem W, Fleming AJ. Induction of differentiation in the shoot apical meristem by transient overexpression of a retinoblastoma-related protein. PLANT PHYSIOLOGY 2006; 141:1338-48. [PMID: 16815954 PMCID: PMC1533950 DOI: 10.1104/pp.106.083022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Revised: 06/22/2006] [Accepted: 06/25/2006] [Indexed: 05/10/2023]
Abstract
The shoot apical meristem contains cells that undergo continual growth and division to generate the building blocks for the aerial portion of the plant. As cells leave the meristem, they undergo differentiation to form specific cell types. Most notably, heterotrophic cells of the meristem rapidly gain autotrophic capability by synthesis and assembly of components of the chloroplast. At the same time, cells undergo enlargement via vacuolation. Despite significant advances in the characterization of transcriptional networks involved in meristem maintenance and leaf determination, our understanding of the actual mechanism of meristem cell differentiation remains very limited. Using a microinduction technique, we show that local, transient overexpression of a retinoblastoma-related (RBR) protein in the shoot apical meristem is sufficient to trigger cells in the meristem to undergo the initial stages of differentiation. Taken together with recent data showing that RBR protein plays a key role in restricting stem cell differentiation in the root apical meristem, our data contribute to an emerging picture of RBR proteins as a central part of the mechanism controlling meristem cell differentiation.
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Affiliation(s)
- Joanna Wyrzykowska
- Institute of Plant Sciences, Swiss Federal Institute of Technology Zürich, CH-8092 Zurich, Switzerland
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28
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Kawamura K, Murray JAH, Shinmyo A, Sekine M. Cell cycle regulated D3-type cyclins form active complexes with plant-specific B-type cyclin-dependent kinase in vitro. PLANT MOLECULAR BIOLOGY 2006; 61:311-27. [PMID: 16786309 DOI: 10.1007/s11103-006-0014-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Accepted: 01/23/2006] [Indexed: 05/10/2023]
Abstract
Tobacco (Nicotiana tabacum L.) cv Bright Yellow-2 (BY-2) cells are the most highly synchronizable plant cell culture, and previously we used them to analyze cell cycle regulation of cyclin-dependent kinases (CDKs) containing the cyclin binding motifs PSTAIRE (CDKA) and PPTA/TLRE (CDKB). Here we describe the analysis of tobacco CycD3 cyclins whose transcripts predominantly accumulate during G2 to M phase, which represents a unique feature of this type of cyclin D in plants. Although protein levels of CycD3s fluctuate with different patterns during the cell cycle, kinase assays revealed that the CycD3-associated kinases phosphorylate histone H1 and the tobacco retinoblastoma related protein (NtRBR1) with two peaks at the G1/S and G2/M boundaries. In vitro pull-down assays revealed that cell cycle-regulated CycD3s bind to CDKA, but more weakly than does CycD3;3, and that they also bind to CDKB and the CDK inhibitor NtKIS1a. Mutations in the cyclin box of the CycD3s showed that two amino acids are required for binding with CDKA and NtKIS1a, but no diminished interaction was observed with CDKB. A reconstituted kinase assay was adapted for use with bacterially produced GST-CycD3s, and kinase activity could be activated by incubation of extracts from exponentially growing BY-2 cells. Such activated complexes contained CDKA and CDKB, and the reconstituted GST-CycD3 mutants, retaining binding ability to CDKB, showed kinase activity, suggesting that these cell cycle-regulated CycD3s form active complexes with both A- and B-type CDKs in vitro.
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Affiliation(s)
- Kazue Kawamura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Takayama, Ikoma, Japan
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29
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Gegas VC, Doonan JH. Expression of cell cycle genes in shoot apical meristems. PLANT MOLECULAR BIOLOGY 2006; 60:947-61. [PMID: 16724263 DOI: 10.1007/s11103-006-0011-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Accepted: 01/18/2006] [Indexed: 05/09/2023]
Abstract
This article reviews cell proliferation in the shoot apical meristem. The morphology and function of the meristem depends on the positional control of cell growth and division. The review describes the historical framework of research in this area and then discusses the regulatory pathways that might link developmental controls to the core cell cycle machinery.
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Affiliation(s)
- Vasilis C Gegas
- Department of Cell and Developmental Biology, John Innes Centre, Colney Lane, NR4 7UH, Norwich, UK
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30
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Iwakawa H, Shinmyo A, Sekine M. Arabidopsis CDKA;1, a cdc2 homologue, controls proliferation of generative cells in male gametogenesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 45:819-31. [PMID: 16460514 DOI: 10.1111/j.1365-313x.2005.02643.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The protein kinase cdc2 is conserved throughout eukaryotes and acts as a key regulator of the cell cycle. In plants, A-type cyclin-dependent kinase (CDKA), a homologue of cdc2, has a role throughout the cell cycle. Here we show that a loss-of-function mutation in CDKA;1, encoding the only Arabidopsis CDKA, results in lethality of the male gametophyte. Heterozygous plants produced mature siliques containing about 50% aborted seeds, and segregation distortion was observed in paternal inheritance. Microspores normally undergo an asymmetric cell division, pollen mitosis I (PMI), to produce bicellular pollen grains. The larger vegetative cell does not divide, but the smaller generative cell undergoes mitosis, PMII, to form the two sperm cells, thereby generating tricellular pollen grains. The cdka-1 mutant, however, produces mature bicellular pollen grains, consisting of a single sperm-like cell and a vegetative cell, due to failure of PMII. The mutant sperm-like cell is fertile, and preferentially fuses with the egg cell to initiate embryogenesis. As the central cell nucleus remains unfertilized, however, double fertilization does not occur. In heterozygous plants, the embryo is arrested at the globular stage, most likely because of loss of endosperm development, whereas it is arrested at the one- or two-cell stage in presumptive homozygous plants. Thus, CDKA;1 is essential for cell division of the generative cell in male gametogenesis.
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Affiliation(s)
- Hidekazu Iwakawa
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan
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31
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Sabelli PA, Dante RA, Leiva-Neto JT, Jung R, Gordon-Kamm WJ, Larkins BA. RBR3, a member of the retinoblastoma-related family from maize, is regulated by the RBR1/E2F pathway. Proc Natl Acad Sci U S A 2005; 102:13005-12. [PMID: 16141340 PMCID: PMC1201608 DOI: 10.1073/pnas.0506160102] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Retinoblastoma-related (RBR) proteins regulate cell division in higher eukaryotes by controlling the adenovirus E2 promoter binding factor (E2F)/dimerization partner (DP) family of transcription factors that regulate expression of many genes involved in cell-cycle progression. We identified a previously undescribed member of the maize RBR family, RBR3, which has the characteristic structure and binding activities of pocket proteins, where interaction depends on a LxCxE motif in the partner proteins and a critical cysteine within the B pocket domain. Like other RBR proteins, RBR3 appears to be regulated by phosphorylation mediated by cyclin-dependent kinases. During endosperm development, RBR3 expression is restricted to the mitotic stage preceding the onset of endoreduplication. This finding suggests a role distinct from RBR1, which is constitutively expressed. Two sites in the RBR3 promoter bind to complexes containing maize E2F1 and DP proteins. Expression of wheat dwarf virus RepA protein, which blocks RBR1 activity and stimulates cell proliferation, dramatically up-regulates RBR3, but not RBR1, RNA in embryogenic maize calli. The results indicate that RBR3 expression is controlled by RBR1 through the activity of E2F/DP and that RBR3 is the maize equivalent of mammalian p107. Furthermore, maize and related grasses might have evolved a compensatory mechanism among distinct types of RBR proteins to ensure robust control of pocket protein activity.
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Affiliation(s)
- Paolo A Sabelli
- Department of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA
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