scholarly journals A Molecular Framework for Plant Regeneration

Science ◽  
2006 ◽  
Vol 311 (5759) ◽  
pp. 385-388 ◽  
Author(s):  
Jian Xu ◽  
Hugo Hofhuis ◽  
Renze Heidstra ◽  
Michael Sauer ◽  
Jiří Friml ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Cell Fate ◽  
Molecular Mechanisms ◽  
Plant Hormone ◽  
Auxin Transport ◽  
Root Tips ◽  
Root Stem Cell ◽  
Regeneration Response ◽  
A Cell ◽  
Molecular Framework

Plants and some animals have a profound capacity to regenerate organs from adult tissues. Molecular mechanisms for regeneration have, however, been largely unexplored. Here we investigate a local regeneration response in Arabidopsis roots. Laser-induced wounding disrupts the flow of auxin—a cell-fate–instructive plant hormone—in root tips, and we demonstrate that resulting cell-fate changes require the PLETHORA, SHORTROOT, and SCARECROW transcription factors. These transcription factors regulate the expression and polar position of PIN auxin efflux–facilitating membrane proteins to reconstitute auxin transport in renewed root tips.Thus, a regeneration mechanism using embryonic root stem-cell patterning factors first responds to and subsequently stabilizes a new hormone distribution.

The dynamics of auxin transport

1980 ◽  
Vol 209 (1177) ◽  
pp. 489-511 ◽  
Keyword(s):  
Plant Hormone ◽  
Auxin Transport ◽  
Unit Area ◽  
Aqueous Media ◽  
Diffusion Constant ◽  
Directed Motion ◽  
Concentration Gradients ◽  
Forward Movement ◽  
A Cell ◽  
Polar Mechanism

The plant hormone auxin is transported with a well defined velocity through many tissues. To explain this, one type of theory proposes that a polar mechanism operates at the interface between two cells. I show that, if auxin diffuses freely through the interior of cells, then there is an upper limit to the velocity that can be achieved by such a mechanism. This is compatible with the observed velocities provided that the diffusion constant for auxin within a cell is not much less than that measured for auxin in aqueous media. Cytoplasmic streaming, unless specially organized, would not assist the movement of auxin. This is because rapid diffusion between streams will cancel out any directed motion. I also show that the permeability that characterizes the forward movement between cells must exceed a certain limit. If auxin moves mainly through the cytoplasm, which occupies only a small part of the volume of a cell, then the permeability per unit area of membrane needed to achieve a given velocity is much reduced. Transport would be channelled through the cytoplasm if the membrane bounding the vacuole were relatively impermeable to auxin. The theory that I develop leads to predictions about, for example, the route of auxin and its concentration gradients within cells, and the dependence of velocity on cell length.

scholarly journals Auxin-transporting ABC transporters are defined by a conserved D/E-P motif regulated by a prolylisomerase

2020 ◽  
Vol 295 (37) ◽  
pp. 13094-13105 ◽  
Author(s):  
Pengchao Hao ◽  
Jian Xia ◽  
Jie Liu ◽  
Martin Di Donato ◽  
Konrad Pakula ◽  
...  
Keyword(s):  
Abc Transporters ◽  
Plant Hormone ◽  
Auxin Transport ◽  
Physical Interaction ◽  
Transport Activity ◽  
Nucleotide Binding Domain ◽  
Higher Plant ◽  
Ppiase Activity ◽  
Auxin Distribution ◽  
A Cell

The plant hormone auxin must be transported throughout plants in a cell-to-cell manner to affect its various physiological functions. ABCB transporters are critical for this polar auxin distribution, but the regulatory mechanisms controlling their function is not fully understood. The auxin transport activity of ABCB1 was suggested to be regulated by a physical interaction with FKBP42/Twisted Dwarf1 (TWD1), a peptidylprolyl cis-trans isomerase (PPIase), but all attempts to demonstrate such a PPIase activity by TWD1 have failed so far. By using a structure-based approach, we identified several surface-exposed proline residues in the nucleotide binding domain and linker of Arabidopsis ABCB1, mutations of which do not alter ABCB1 protein stability or location but do affect its transport activity. P1008 is part of a conserved signature D/E-P motif that seems to be specific for auxin-transporting ABCBs, which we now refer to as ATAs. Mutation of the acidic residue also abolishes auxin transport activity by ABCB1. All higher plant ABCBs for which auxin transport has been conclusively proven carry this conserved motif, underlining its predictive potential. Introduction of this D/E-P motif into malate importer, ABCB14, increases both its malate and its background auxin transport activity, suggesting that this motif has an impact on transport capacity. The D/E-P1008 motif is also important for ABCB1-TWD1 interactions and activation of ABCB1-mediated auxin transport by TWD1. In summary, our data imply a new function for TWD1 acting as a putative activator of ABCB-mediated auxin transport by cis-trans isomerization of peptidyl-prolyl bonds.

Regulation of cell survival and proliferation by the FOXO (Forkhead box, class O) subfamily of Forkhead transcription factors

2003 ◽  
Vol 31 (1) ◽  
pp. 292-297 ◽  
Author(s):  
K.U. Birkenkamp ◽  
P.J. Coffer
Keyword(s):  
Transcription Factors ◽  
Cell Survival ◽  
Cell Fate ◽  
Nuclear Export ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Acute Lymphocytic Leukaemia ◽  
Cell Fate Decisions ◽  
Forkhead Transcription Factors ◽  
Forkhead Box

Recently, the FOXO (Forkhead box, class O) subfamily of Forkhead transcription factors has been identified as direct targets of phosphoinositide 3-kinase-mediated signal transduction. The AFX (acute-lymphocytic-leukaemia-1 fused gene from chromosome X), FKHR (Forkhead in rhabdomyosarcoma) and FKHR-L1 (FKHR-like 1) transcription factors are directly phosphorylated by protein kinase B, resulting in nuclear export and inhibition of transcription. This signalling pathway was first identified in the nematode worm Caenorhabditis elegans, where it has a role in regulation of the life span of the organism. Studies have shown that this evolutionarily conserved signalling module has a role in regulation of both cell-cycle progression and cell survival in higher eukaryotes. These effects are co-ordinated by FOXO-mediated induction of a variety of specific target genes that are only now beginning to be identified. Interestingly, FOXO transcription factors appear to be able to regulate transcription through both DNA-binding-dependent and -independent mechanisms. Our understanding of the regulation of FOXO activity, and defining specific transcriptional targets, may provide clues to the molecular mechanisms controlling cell fate decisions to divide, differentiate or die.

The effect of intracellular geometry on auxin transport. I. Centrifugation experiments

1981 ◽  
Vol 214 (1194) ◽  
pp. 53-67 ◽  
Keyword(s):  
Thin Layer ◽  
High Velocity ◽  
Plant Hormone ◽  
Auxin Transport ◽  
The Other ◽  
Permeability Barrier ◽  
Cell Geometry ◽  
Internal Cell ◽  
A Cell ◽  
High Concentrations

When coleoptiles are centrifuged, the velocity of transport of the plant hormone auxin is dramatically altered. I show here that this may be due to changes in internal cell geometry. The tonoplast, the membrane surrounding the vacuole, may present a substantial permeability barrier for the diffusion of auxin. After centrifugation, the cytoplasm sediments to one end of the cell, displacing the vacuole to the other. If auxin, on entering the cell, must first accumulate in a mass of cytoplasm before crossing the tonoplast, the velocity will be lowered. If, on the other hand, there is only a thin layer of cytoplasm where auxin enters, high concentrations will quickly build up and enable auxin to cross the tonoplast, giving a high velocity. This would explain why centrifugation in a basal direction increases velocity, while apical centrifugation de­creases it. If this explanation is correct, and if the tonoplast constitutes an appreciable permeability barrier, then the position of the vacuole may strongly influence the flux of auxin inside a cell. I show in the adjoining paper that this can explain the changed transport pattern seen during the geotropic response.

scholarly journals Molecular Logic of Hypothalamus Development

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A507-A507
Author(s):  
Thomas Kim
Keyword(s):  
Transcription Factors ◽  
Cell Fate ◽  
Regulatory Networks ◽  
Molecular Mechanisms ◽  
Developmental Time ◽  
Specific Gene ◽  
Molecular Logic ◽  
Hypothalamic Nuclei ◽  
Physiological Homeostasis ◽  
Mutant Lines

Abstract The hypothalamus is a central regulator of physiological homeostasis. During development, multiple transcription factors coordinate the patterning and specification of hypothalamic nuclei. However, the molecular mechanisms controlling hypothalamic patterning and cell fate specification are poorly understood. To identify genes that control these processes, we have previously used single-cell RNA sequencing (scRNA-Seq) to profile mouse hypothalamic gene expression across multiple developmental time points and established database HyDD (Hypothalamus Developmental Database). We next used HyDD to characterize multiple mutant lines targetting key transcription factors that came out from our scRNA-Seq database (Nkx2.2, Dlx1/2, Isl1, Foxd1, Lhx2), and was able to comprehensively characterize mutants that have altered hypothalamic patterning. Our phenotype result supports a modified columnar model of organization for the diencephalon, where prethalamus and hypothalamus are situated in adjacent dorsal and ventral domains of the anterior diencephalon. Furthermore, using our mouse hypothalamus as a guideline, we are comparing scRNA-Seq dataset of developing chicken, zebrafish and human hypothalamus, to identify evolutionarily conserved and divergent region-specific gene regulatory networks. Lastly, we are improving mouse HyDD, in order to characterize adult hypothalamus neuronal subtypes.

scholarly journals Use of Transcriptomic Analyses to Elucidate the Mechanism Governing Nodal Root Development in Eremochloa ophiuroides (Munro) Hack.

2021 ◽  
Vol 12 ◽  
Author(s):  
Rui Wang ◽  
Haoyan Zhao ◽  
Hailin Guo ◽  
Junqin Zong ◽  
Jianjian Li ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Transcription Factors ◽  
Root Development ◽  
Molecular Mechanisms ◽  
Homologous Gene ◽  
Root Tips ◽  
Rooting Ability ◽  
Nodal Roots ◽  
Nodal Root ◽  
Eremochloa Ophiuroides

Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] is a perennial warm-season grass that originated in China, and its speed of nodal rooting is important for lawn establishment. In our study, centipedegrass nodal rooting ability was limited by node aging. Transcriptome sequencing of nodal roots after 0, 2, 4, and 8 days of water culture was performed to investigate the molecular mechanisms of root development. GO enrichment and KEGG pathway analyses of DEGs indicated that plant hormone signal transduction and transcription factors might play important roles in centipedegrass nodal root growth. Among them, E3 ubiquitin-protein ligases participated in multiple hormone signal transduction pathways and interacted with transcription factors. Furthermore, an E3 ubiquitin protein ligase EoSINAT5 overexpressed in rice resulted in longer roots and more numerous root tips, while knockout of LOC_Os07g46560 (the homologous gene of EoSINAT5 in rice) resulted in shorter roots and fewer root tips. These results indicated that EoSINAT5 and its homologous gene are able to promote nodal root development. This research presents the transcriptomic analyses of centipedegrass nodal roots, and may contribute to elucidating the mechanism governing the development of nodal roots and facilitates the use of molecular breeding in improving rooting ability.

MATHEMATICAL MODELING OF AUXIN TRANSPORT IN PROTOXYLEM AND PROTOPHLOEM OF ARABIDOPSIS THALIANA ROOT TIPS

2013 ◽  
Vol 11 (01) ◽  
pp. 1340010 ◽  
Author(s):  
EKATERINA S. NOVOSELOVA ◽  
VICTORIA V. MIRONOVA ◽  
NADYA A. OMELYANCHUK ◽  
FEDOR V. KAZANTSEV ◽  
VITALY A. LIKHOSHVAI
Keyword(s):  
Arabidopsis Thaliana ◽  
Active Transport ◽  
Auxin Transport ◽  
Positional Information ◽  
Root Tip ◽  
Root Tips ◽  
Auxin Distribution ◽  
A Cell ◽  
Optimal Values ◽  
Main Regulator

Phytohormone auxin is the main regulator of plant growth and development. Nonuniform auxin distribution in plant tissue sets positional information, which determines morphogenesis. Auxin is transported in tissue by means of diffusion and active transport through the cell membrane. There is a number of auxin carriers performing its influx into a cell (AUX\LAX family) or efflux from a cell (PIN, PGP families). The paper presents mathematical models for auxin transport in vascular tissues of Arabidopsis thaliana L.root tip, namely protophloem and protoxylem. Tissue specificity of auxin active transport was considered in these models. There is PIN-mediated auxin efflux in both protoxylem and protophloem, but AUX1-mediated influx exists only in protophloem. Optimal values of parameters were adjusted for model solutions to fit the experimentally observed auxin distributions in the root tip. Based on simulation results we predicted that shoot-derived auxin flow to protophloem is lower than one to protoxylem, and the efficiency of PIN-mediated auxin transport in protophloem is higher than in protoxylem. In summary, our simulation showed that despite the same auxin distribution pattern, provascular tissues in the root tip differ in dynamics of auxin transport.

scholarly journals The Transcriptional Control of Lymphatic Vascular Development

Physiology ◽  
2011 ◽  
Vol 26 (3) ◽  
pp. 146-155 ◽  
Author(s):  
Mathias Francois ◽  
Natasha L. Harvey ◽  
Benjamin M. Hogan
Keyword(s):  
Transcription Factors ◽  
Cell Fate ◽  
Transcriptional Control ◽  
Molecular Mechanisms ◽  
Developmental Process ◽  
Vascular Development ◽  
Lymphatic Vessels ◽  
Lymphatic Endothelial Cell ◽  
Transcriptional Networks ◽  
Genetic Manipulations

More than 100 years ago, Florence Sabin suggested that lymphatic vessels develop by sprouting from preexisting blood vessels, but it is only over the past decade that the molecular mechanisms underpinning lymphatic vascular development have begun to be elucidated. Genetic manipulations in mice have identified a transcriptional hub comprised of Prox1, CoupTFII, and Sox18 that is essential for lymphatic endothelial cell fate specification. Recent work has identified a number of additional transcription factors that regulate later stages of lymphatic vessel differentiation and maturation. This review highlights recent advances in our understanding of the transcriptional control of lymphatic vascular development and reflects on efforts to better understand the activities of transcriptional networks during this discrete developmental process. Finally, we highlight the transcription factors associated with human lymphatic vascular disorders, demonstrating the importance of understanding how the activity of these key molecules is regulated, with a view toward the development of innovative therapeutic avenues.

scholarly journals Yeast cell fate control by temporal redundancy modulation of transcription factor paralogs

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yan Wu ◽  
Jiaqi Wu ◽  
Minghua Deng ◽  
Yihan Lin
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Stress Response ◽  
Cell Fate ◽  
Functional Redundancy ◽  
Yeast Cells ◽  
Fate Control ◽  
A Cell ◽  
Temporal Redundancy ◽  
Cell Fate Control

AbstractRecent single-cell studies have revealed that yeast stress response involves transcription factors that are activated in pulses. However, it remains unclear whether and how these dynamic transcription factors temporally interact to regulate stress survival. Here we show that budding yeast cells can exploit the temporal relationship between paralogous general stress regulators, Msn2 and Msn4, during stress response. We find that individual pulses of Msn2 and Msn4 are largely redundant, and cells can enhance the expression of their shared targets by increasing their temporal divergence. Thus, functional redundancy between these two paralogs is modulated in a dynamic manner to confer fitness advantages for yeast cells, which might feed back to promote the preservation of their redundancy. This evolutionary implication is supported by evidence from Msn2/Msn4 orthologs and analyses of other transcription factor paralogs. Together, we show a cell fate control mechanism through temporal redundancy modulation in yeast, which may represent an evolutionarily important strategy for maintaining functional redundancy between gene duplicates.

scholarly journals Klf5 establishes bi-potential cell fate by dual regulation of ICM and TE specification genes

2021 ◽  
Author(s):  
Martin Kinisu ◽  
Yong Jin Choi ◽  
Claudia Cattoglio ◽  
Ke Liu ◽  
Hector Roux de Bezieux ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Cell Fate ◽  
Endogenous Retroviruses ◽  
Preimplantation Embryos ◽  
Cell State ◽  
Upstream Regulator ◽  
Evolutionarily Conserved ◽  
A Cell ◽  
Dual Activation ◽  
Transcription Program

SummaryEarly blastomeres of mouse preimplantation embryos exhibit bi-potential cell fate, capable of generating both embryonic and extra-embryonic lineages in blastocysts. Here, we identified three major 2 cell (2C) specific endogenous retroviruses (ERVs) as the molecular hallmark of the bi-potential plasticity. Using the LTRs of all three 2C-ERVs, we identified Klf5 as their major upstream regulator. Klf5 is essential for bi-potential cell fate: a single Klf5-overexpressing ESC generated terminally differentiated embryonic and extra-embryonic lineages in chimeric embryos, and Klf5 directly induces both ICM and TE specification genes. Intriguingly, Klf5 and Klf4 act redundantly during ICM specification, whereas Klf5 deficiency alone impairs TE specification. Klf5 is regulated by multiple 2C-specific transcription factors, particularly Dux, and the Dux/Klf5 axis is evolutionarily conserved. Altogether, the 2C-specific transcription program converges on Klf5 to establish bi-potential cell fate, enabling a cell state with dual activation of ICM and TE genes.

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