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Knox JP, Benitez-Alfonso Y. Roles and regulation of plant cell walls surrounding plasmodesmata. CURRENT OPINION IN PLANT BIOLOGY 2014; 22:93-100. [PMID: 25286000 DOI: 10.1016/j.pbi.2014.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/16/2014] [Accepted: 09/20/2014] [Indexed: 05/28/2023]
Abstract
In plants, the intercellular transport of simple and complex molecules can occur symplastically through plasmodesmata. These are membranous channels embedded in cell walls that connect neighbouring cells. The properties of the cell walls surrounding plasmodesmata determine their transport capacity and permeability. These cell wall micro-domains are enriched in callose and have a characteristic pectin distribution. Cell wall modifications, leading to changes in plasmodesmata structure, have been reported to occur during development and in response to environmental signals. Cell wall remodelling enzymes target plasmodesmata to rapidly control intercellular communication in situ. Here we describe current knowledge on the composition of cell walls at plasmodesmata sites and on the proteins and signals that modify cell walls to regulate plasmodesmata aperture.
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Affiliation(s)
- J Paul Knox
- Centre for Plant Sciences, School of Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Yoselin Benitez-Alfonso
- Centre for Plant Sciences, School of Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
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52
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Dettmann A, Heilig Y, Valerius O, Ludwig S, Seiler S. Fungal communication requires the MAK-2 pathway elements STE-20 and RAS-2, the NRC-1 adapter STE-50 and the MAP kinase scaffold HAM-5. PLoS Genet 2014; 10:e1004762. [PMID: 25411845 PMCID: PMC4239118 DOI: 10.1371/journal.pgen.1004762] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/18/2014] [Indexed: 11/30/2022] Open
Abstract
Intercellular communication is critical for the survival of unicellular organisms as well as for the development and function of multicellular tissues. Cell-to-cell signaling is also required to develop the interconnected mycelial network characteristic of filamentous fungi and is a prerequisite for symbiotic and pathogenic host colonization achieved by molds. Somatic cell–cell communication and subsequent cell fusion is governed by the MAK-2 mitogen activated protein kinase (MAPK) cascade in the filamentous ascomycete model Neurospora crassa, yet the composition and mode of regulation of the MAK-2 pathway are currently unclear. In order to identify additional components involved in MAK-2 signaling we performed affinity purification experiments coupled to mass spectrometry with strains expressing functional GFP-fusion proteins of the MAPK cascade. This approach identified STE-50 as a regulatory subunit of the Ste11p homolog NRC-1 and HAM-5 as cell-communication-specific scaffold protein of the MAPK cascade. Moreover, we defined a network of proteins consisting of two Ste20-related kinases, the small GTPase RAS-2 and the adenylate cyclase capping protein CAP-1 that function upstream of the MAK-2 pathway and whose signals converge on the NRC-1/STE-50 MAP3K complex and the HAM-5 scaffold. Finally, our data suggest an involvement of the striatin interacting phosphatase and kinase (STRIPAK) complex, the casein kinase 2 heterodimer, the phospholipid flippase modulators YPK-1 and NRC-2 and motor protein-dependent vesicle trafficking in the regulation of MAK-2 pathway activity and function. Taken together, these data will have significant implications for our mechanistic understanding of MAPK signaling and for homotypic cell–cell communication in fungi and higher eukaryotes. Appropriate cellular responses to external stimuli depend on the highly orchestrated activity of interconnected signaling cascades. One crucial level of control arises from the formation of discrete complexes through scaffold proteins that bind multiple components of a given pathway. Central for our understanding of these signaling platforms is the archetypical MAP kinase scaffold Ste5p, a protein that is restricted to budding yeast and close relatives. We identified HAM-5, a protein highly conserved in filamentous ascomycete fungi, as cell–cell communication-specific scaffold protein of the Neurospora crassa MAK-2 cascade (homologous to the budding yeast pheromone pathway). We also describe a network of upstream acting proteins, consisting of two Ste20-related kinases, the small G-protein RAS-2 and the adenylate cyclase capping protein CAP-1, whose signals converge on HAM-5. Our work has implications for the mechanistic understanding of MAP kinase scaffold proteins and their function during intercellular communication in eukaryotic microbes as well as higher eukaryotes.
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Affiliation(s)
- Anne Dettmann
- Institute for Biology II – Molecular Plant Physiology, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Yvonne Heilig
- Institute for Biology II – Molecular Plant Physiology, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Oliver Valerius
- Institute for Microbiology and Genetics, University of Goettingen, Goettingen, Germany
| | - Sarah Ludwig
- Institute for Biology II – Molecular Plant Physiology, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Stephan Seiler
- Institute for Biology II – Molecular Plant Physiology, Albert-Ludwigs University Freiburg, Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs University Freiburg, Freiburg, Germany
- * E-mail:
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53
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Engel PA. Does metabolic failure at the synapse cause Alzheimer's disease? Med Hypotheses 2014; 83:802-8. [PMID: 25456790 DOI: 10.1016/j.mehy.2014.10.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 10/15/2014] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) a neurodegenerative disorder of widely distributed cortical networks evolves over years while A beta (Aβ) oligomer neurotoxicity occurs within seconds to minutes. This disparity combined with disappointing outcomes of anti-amyloid clinical trials challenges the centrality of Aβ as principal mediator of neurodegeneration. Reconsideration of late life AD as the end-product of intermittent regional failure of the neuronal support system to meet the needs of vulnerable brain areas offers an alternative point of view. This model introduces four ideas: (1) That Aβ is a synaptic signaling peptide that becomes toxic in circumstances of metabolic stress. (2) That intense synaptic energy and maintenance requirements of cortical hubs may exceed resources during peak demand initiating a neurotoxic cascade in these selectively vulnerable regions. (3) That axonal transport to and from neuron soma cannot account fully for high mitochondrial densities and other requirements of distant terminal axons. (4) That neurons as specialists in information management, delegate generic support functions to astrocytes and other cell types. Astrocytes use intercellular transport by exosomes and tunneling nanotubes (TNTs) to deliver mitochondria, substrates and protein reprocessing services to axonal sites distant from neuronal soma. This viewpoint implicates the brain's support system and its disruption by various age and disease-related insults as significant mediators of neurodegenerative disease. A better understanding of this system should broaden concepts of neurodegeneration and facilitate development of effective treatments.
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Affiliation(s)
- Peter A Engel
- Geriatric Research, Education and Clinical Center, VA Boston Healthcare System, Harvard Medical School, United States.
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54
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Urban PL. Compartmentalised chemistry: from studies on the origin of life to engineered biochemical systems. NEW J CHEM 2014. [DOI: 10.1039/c4nj00894d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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55
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Seli E, Babayev E, Collins SC, Nemeth G, Horvath TL. Minireview: Metabolism of female reproduction: regulatory mechanisms and clinical implications. Mol Endocrinol 2014; 28:790-804. [PMID: 24678733 DOI: 10.1210/me.2013-1413] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Female fertility is highly dependent on successful regulation of energy metabolism. Central processes in the hypothalamus monitor the metabolic state of the organism and, together with metabolic hormones, drive the peripheral availability of energy for cellular functions. In the ovary, the oocyte and neighboring somatic cells of the follicle work in unison to achieve successful metabolism of carbohydrates, amino acids, and lipids. Metabolic disturbances such as anorexia nervosa, obesity, and diabetes mellitus have clinically important consequences on human reproduction. In this article, we review the metabolic determinants of female reproduction and their role in infertility.
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Affiliation(s)
- Emre Seli
- Department of Obstetrics, Gynecology, and Reproductive Sciences (E.S., E.B., S.C., T.L.H.), Yale School of Medicine, New Haven, Connecticut 06520; Department of Obstetrics and Gynecology (G.N., T.L.H.), University of Szeged, Faculty of Medicine, Szeged, Hungary 6701; Department of Comparative Medicine (T.L.H.), Yale School of Medicine, New Haven, Connecticut 06520; and the Department of Neurobiology (T.L.H.), Yale School of Medicine, New Haven, Connecticut 06520
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56
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Chen H, Jackson D, Kim JY. Identification of evolutionarily conserved amino acid residues in homeodomain of KNOX proteins for intercellular trafficking. PLANT SIGNALING & BEHAVIOR 2014; 9:e28355. [PMID: 24603432 PMCID: PMC4091555 DOI: 10.4161/psb.28355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 02/25/2014] [Accepted: 02/25/2014] [Indexed: 06/03/2023]
Abstract
Maize knotted (KN1) homeodomain (HD) protein is a well-known mobile transcription factor crucial for stem cell maintenance. Recent studies have revealed that the trihelical HD of knotted1-like homeobox (KNOX) proteins is necessary and sufficient for selective cell-to-cell trafficking. Also, the efficient trafficking ability for HD is likely to be acquired during the evolution of early nonvascular land plants. Here, using the point-mutated HD of KN1 and shoot meristemless (STM) in the trichome rescue system, together with molecular structure modeling, we have found the evolutionarily conserved amino acid residues, such as arginine in helix α1 and leucine in helix α3, which are essential for intercellular trafficking. Our studies provided important clues for the 3-dimensional protein structure required for cell-to-cell movement of non-cell-autonomous transcription factors.
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Affiliation(s)
- Huan Chen
- Division of Applied Life Science (BK21plus); Plant Molecular Biology & Biotechnology Research Center; Gyeongsang National University; Jinju, Korea
| | - David Jackson
- Cold Spring Harbor Laboratory; Cold Spring Harbor, NY USA
| | - Jae-Yean Kim
- Division of Applied Life Science (BK21plus); Plant Molecular Biology & Biotechnology Research Center; Gyeongsang National University; Jinju, Korea
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57
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Tucker MR, Koltunow AMG. Traffic monitors at the cell periphery: the role of cell walls during early female reproductive cell differentiation in plants. CURRENT OPINION IN PLANT BIOLOGY 2014; 17:137-45. [PMID: 24507505 DOI: 10.1016/j.pbi.2013.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 11/14/2013] [Accepted: 11/27/2013] [Indexed: 05/05/2023]
Abstract
The formation of female gametes in plants occurs within the ovule, a floral organ that is also the precursor of the seed. Unlike animals, plants lack a typical germline separated from the soma early in development and rely on positional signals, including phytohormones, mobile mRNAs and sRNAs, to direct diploid somatic precursor cells onto a reproductive program. In addition, signals moving between plant cells must overcome the architectural limitations of a cell wall which surrounds the plasma membrane. Recent studies have addressed the molecular and histological signatures of young ovule cells and indicate that dynamic cell wall changes occur over a short developmental window. These changes in cell wall properties impact signal flow and ovule cell identity, thereby aiding the establishment of boundaries between reproductive and somatic ovule domains.
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Affiliation(s)
- Matthew R Tucker
- Australian Research Council (ARC) Centre of Excellence in Plant Cell Walls, University of Adelaide, Waite Campus, Urrbrae, SA 5064, Australia.
| | - Anna M G Koltunow
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Plant Industry, Hartley Grove, Waite Campus, Urrbrae, SA 5064, Australia
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58
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Marzec M, Kurczynska E. Importance of symplasmic communication in cell differentiation. PLANT SIGNALING & BEHAVIOR 2014; 9:e27931. [PMID: 24476959 PMCID: PMC4091221 DOI: 10.4161/psb.27931] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/21/2014] [Accepted: 01/21/2014] [Indexed: 05/18/2023]
Abstract
Symplasmic communication via plasmodesmata (PD) is part of the system of information exchange between plant cells. Molecules that pass through the PD include ions, some hormones, minerals, amino acids, and sugars but also proteins, transcription factors, and different classes of RNA, and as such PD can participate in the coordination of plant growth and development. This review summarizes the current literature on this subject and the role of PD in signal exchange, the importance of symplasmic communication and symplasmic domains in plant cell differentiation, and highlights the future prospective in the exploration of PD functions in plants. Moreover, this review also describes the potential use of barley root epidermis and non-zygotic embryogenesis in study of symplasmic communication during cell differentiation.
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Affiliation(s)
- Marek Marzec
- Department of Genetics; Faculty of Biology and Environmental Protection; University of Silesia; Katowice, Poland
| | - Ewa Kurczynska
- Laboratory of Cell Biology; Faculty of Biology and Environmental Protection; University of Silesia; Katowice, Poland
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Shen KF, Osmani AH, Govindaraghavan M, Osmani SA. Mitotic regulation of fungal cell-to-cell connectivity through septal pores involves the NIMA kinase. Mol Biol Cell 2014; 25:763-75. [PMID: 24451264 PMCID: PMC3952847 DOI: 10.1091/mbc.e13-12-0718] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Septal pores—the intercellular bridges of fungi—are open during interphase but closed at mitosis. The NIMA kinase mitotically regulates septal pore closing and opening potentially via mechanisms analogous to how it regulates mitotic nuclear pores. The findings explain how and why physically connected Aspergillus cells can maintain mitotic autonomy. Intercellular bridges are a conserved feature of multicellular organisms. In multicellular fungi, cells are connected directly via intercellular bridges called septal pores. Using Aspergillus nidulans, we demonstrate for the first time that septal pores are regulated to be opened during interphase but closed during mitosis. Septal pore–associated proteins display dynamic cell cycle–regulated locations at mature septa. Of importance, the mitotic NIMA kinase locates to forming septa and surprisingly then remains at septa throughout interphase. However, during mitosis, when NIMA transiently locates to nuclei to promote mitosis, its levels at septa drop. A model is proposed in which NIMA helps keep septal pores open during interphase and then closed when it is removed from them during mitosis. In support of this hypothesis, NIMA inactivation is shown to promote interphase septal pore closing. Because NIMA triggers nuclear pore complex opening during mitosis, our findings suggest that common cell cycle regulatory mechanisms might control septal pores and nuclear pores such that they are opened and closed out of phase to each other during cell cycle progression. The study provides insights into how and why cytoplasmically connected Aspergillus cells maintain mitotic autonomy.
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Affiliation(s)
- Kuo-Fang Shen
- Department of Molecular Genetics and Molecular, Cellular and Developmental Biology Program, Ohio State University, Columbus, OH 43210
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Bivic AL. Evolution and Cell Physiology. 4. Why invent yet another protein complex to build junctions in epithelial cells? Am J Physiol Cell Physiol 2013; 305:C1193-201. [DOI: 10.1152/ajpcell.00272.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The formation of the first epithelium was an essential step for animal evolution, since it has allowed coordination of the behavior of a cell layer and creation of a selective barrier between the internal medium and the outside world. The possibility of coupling the cells in a single layer has allowed morphogenetic events, such as tube formation, or gastrulation, to form more complex animal morphologies. The invention of sealed junctions between cells has allowed, on the other hand, creation of an asymmetry of nutrients or salts between the apical and the basal side of the epithelial layer. Creation of an internal medium has led to homeostasis, allowing the evolution of more complex physiological functions and the emergence of sophisticated animal shapes. During evolution, the origins of the first animals coincided with the invention of several protein complexes, including true cadherins and the polarity protein complexes. How these complexes regulate formation of the apicolateral border and the adherens junctions is still not fully understood. This review focuses on the role of these apical polarity complexes and, in particular, the Crumbs complex, which is essential for proper organization of epithelial layers from Drosophila to humans.
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Affiliation(s)
- André Le Bivic
- Aix-Marseille Université, Centre National de la Recherche Scientifique, UMR 7288, Developmental Biology Institute of Marseille, Marseille, France
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61
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Moving RNA moves RNA forward. SCIENCE CHINA-LIFE SCIENCES 2013; 56:914-20. [DOI: 10.1007/s11427-013-4545-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 08/23/2013] [Indexed: 12/11/2022]
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