Cell Signalling (cell-cell communication) and entropy change of
the cellular system

Lateral inhibition provides the basis for a self-organizing patterning system in which distinct cell states emerge from an otherwise uniform field of cells. The development of the microchaete bristle pattern on the notum of the fruitfly, Drosophila melanogaster , has long served as a popular model of this process. We recently showed that this bristle pattern depends upon a population of dynamic, basal actin-based filopodia, which span multiple cell diameters. These protrusions establish transient signalling contacts between non-neighbouring cells, generating a type of structured noise that helps to yield a well-ordered and spaced pattern of bristles. Here, we develop a general model of protrusion-based patterning to analyse the role of noise in this process. Using a simple asynchronous cellular automata rule-based model we show that this type of structured noise drives the gradual refinement of lateral inhibition-mediated patterning, as the system moves towards a stable configuration in which cells expressing the inhibitory signal are near-optimally packed. By analysing the effects of introducing thresholds required for signal detection in this model of lateral inhibition, our study shows how filopodia-mediated cell–cell communication can generate complex patterns of spots and stripes, which, in the presence of signalling noise, align themselves across a patterning field. Thus, intermittent protrusion-based signalling has the potential to yield robust self-organizing tissue-wide patterns without the need to invoke diffusion-mediated signalling.

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The peptide pheromone-inducible conjugation system of Enterococcus faecalis plasmid pCF10: cell–cell signalling, gene transfer, complexity and evolution

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2007.2043 ◽

2007 ◽

Vol 362 (1483) ◽

pp. 1185-1193 ◽

Cited By ~ 89

Author(s):

Gary M Dunny

Keyword(s):

Cell Signalling ◽

Cell Communication ◽

Large Set ◽

Conjugation System ◽

Molecular Events ◽

Donor Cells ◽

Molecular Machinery ◽

Bacterial Model ◽

Inducible Genes ◽

Cell Cell

Expression of a large set of gene products required for conjugative transfer of the antibiotic resistance plasmid pCF10 is controlled by cell–cell communication between plasmid-free recipient cells and plasmid-carrying donor cells using a peptide mating pheromone cCF10. Most of the recent experimental analysis of this system has focused on the molecular events involved in initiation of the pheromone response in the donor cells, and on the mechanisms by which the donor cells control self-induction by endogenously produced pheromone. Recently, studies of the molecular machinery of conjugation encoded by the pheromone-inducible genes have been initiated. In addition, the system may serve as a useful bacterial model for addressing the evolution of biological complexity.

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Cell–cell signalling in plants: Cross-talk among chloroplasts, mitochondria and plasmodesmata

The Biochemist ◽

10.1042/bio03605011 ◽

2014 ◽

Vol 36 (5) ◽

pp. 11-15

Author(s):

Jacob O. Brunkard ◽

Anne M. Runkel ◽

Patricia C. Zambryski

Keyword(s):

Cell Death ◽

Small Molecules ◽

Developmental Process ◽

Cell Signalling ◽

Cell Communication ◽

Land Plants ◽

Animal Cells ◽

Distinct Mechanism ◽

Septal Pores ◽

Cell Cell

Multicellularity is central to the stunning diversity of biological forms on earth today. In multicellular species, individual cells become dependent on each other, differentiate to specialize their functions, and may even undergo cell death as the whole organism develops. This developmental process requires intense co-ordination of genetic programs and physiology across the organism, relying on communication between cells. There are only a handful of lineages of obligate multicellular eukaryotes – animals, a few groups of fungi, certain algal lineages, and land plants – but each arose independently, and each employs a distinct mechanism of intercellular communication1. Direct physical cell–cell communication between animal cells occurs via gap junctions, which transport only very small molecules, and via tunnelling nanotubes, which permit exchange of larger molecules. Fungal cells never fully separate after cell division, in a sense, because they leave behind septal pores that connect adjacent cytoplasts. In plants, intercellular communication is primarily facilitated by plasmodesmata (PD).

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Cell–cell communication in the plant pathogen Agrobacterium tumefaciens

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2007.2040 ◽

2007 ◽

Vol 362 (1483) ◽

pp. 1135-1148 ◽

Cited By ~ 120

Author(s):

Catharine E White ◽

Stephen C Winans

Keyword(s):

Agrobacterium Tumefaciens ◽

Plant Pathogen ◽

Vibrio Fischeri ◽

Cell Signalling ◽

Infected Plant ◽

Cell Communication ◽

Type Systems ◽

Acylhomoserine Lactone ◽

Ti Plasmids ◽

Cell Cell

The plant pathogen Agrobacterium tumefaciens induces the formation of crown gall tumours at wound sites on host plants by directly transforming plant cells. This disease strategy benefits the bacteria as the infected plant tissue produces novel nutrients, called opines, that the colonizing bacteria can use as nutrients. Almost all of the genes that are required for virulence, and all of the opine uptake and utilization genes, are carried on large tumour-inducing (Ti) plasmids. The observation more than 25 years ago that specific opines are required for Ti plasmid conjugal transfer led to the discovery of a cell–cell signalling system on these plasmids that is similar to the LuxR–LuxI system first described in Vibrio fischeri . All Ti plasmids that have been described to date carry a functional LuxI-type N -acylhomoserine lactone synthase (TraI), and a LuxR-type signal receptor and transcriptional regulator called TraR. The traR genes are expressed only in the presence of specific opines called conjugal opines. The TraR–TraI system provides an important model for LuxR–LuxI-type systems, especially those found in the agriculturally important Rhizobiaceae family. In this review, we discuss current advances in the biochemistry and structural biology of the TraR–TraI system.

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