scholarly journals Chemotaxis as an Emergent Property of a Swarm

2008 ◽  
Vol 190 (20) ◽  
pp. 6811-6816 ◽  
Author(s):  
Rion G. Taylor ◽  
Roy D. Welch
Keyword(s):  
Signal Transduction ◽  
Myxococcus Xanthus ◽  
Bacterial Chemotaxis ◽  
Emergent Property ◽  
Complex Signal ◽  
Cell Contact ◽  
Two Dimensional ◽  
Nutrient Gradient ◽  
Motile Cells ◽  
Agar Substrate

ABSTRACT We have characterized and quantified a form of bacterial chemotaxis that manifests only as an emergent property by measuring symmetry breaking in a swarm of Myxococcus xanthus exposed to a two-dimensional nutrient gradient from within an agar substrate. M. xanthus chemotaxis requires cell-cell contact and coordinated motility, as individual motile cells exhibit only nonvectorial movement in the presence of a nutrient gradient. Genes that specifically affect M. xanthus chemotaxis include at least 10 of the 53 that express enhancer binding proteins of the NtrC-like class, an indication that this behavior is controlled through transcription, most likely by a complex signal transduction network.

scholarly journals CrdS and CrdA Comprise a Two-Component System That Is Cooperatively Regulated by the Che3 Chemosensory System in Myxococcus xanthus

mBio ◽  
2011 ◽  
Vol 2 (4) ◽  
Author(s):  
Jonathan W. Willett ◽  
John R. Kirby
Keyword(s):  
Signal Transduction ◽  
Myxococcus Xanthus ◽  
Complex Signal ◽  
Central Processor ◽  
Two Component System ◽  
Component System ◽  
Chemosensory System ◽  
Content Type ◽  
Phosphorylation State ◽  
Two Component

ABSTRACTMyxococcus xanthusserves as a model organism for development and complex signal transduction. Regulation of developmental aggregation and sporulation is controlled, in part, by the Che3 chemosensory system. The Che3 pathway consists of homologs to two methyl-accepting chemotaxis proteins (MCPs), CheA, CheW, CheB, and CheR but not CheY. Instead, the output for Che3 is the NtrC homolog CrdA, which functions to regulate developmental gene expression. In this paper we have identified an additional kinase, CrdS, which directly regulates the phosphorylation state of CrdA. Both epistasis andin vitrophosphotransfer assays indicate that CrdS functions as part of the Che3 pathway and, in addition to CheA3, serves to regulate CrdA phosphorylation inM. xanthus. We provide kinetic data for CrdS autophosphorylation and demonstrate specificity for phosphotransfer from CrdS to CrdA. We further demonstrate that CheA3 destabilizes phosphorylated CrdA (CrdA~P), indicating that CheA3 likely acts as a phosphatase. Both CrdS and CheA3 control developmental progression by regulating the phosphorylation state of CrdA~P in the cell. These results support a model in which a classical two-component system and a chemosensory system act synergistically to control the activity of the response regulator CrdA.IMPORTANCEWhile phosphorylation-mediated signal transduction is well understood in prototypical chemotaxis and two-component systems (TCS), chemosensory regulation of alternative cellular functions (ACF) has not been clearly defined. The Che3 system inMyxococcus xanthusis a member of the ACF class of chemosensory systems and regulates development via the transcription factor CrdA (chemosensoryregulator ofdevelopment) (K. Wuichet and I. B. Zhulin, Sci. Signal. 3:ra50, 2010; J. R. Kirby and D. R. Zusman, Proc. Natl. Acad. Sci. U. S. A. 100:2008–2013, 2003). We have identified and characterized a homolog of NtrB, designated CrdS, capable of specifically phosphorylating the NtrC homolog CrdA inM. xanthus. Additionally, we demonstrate that the CrdSA two-component system is negatively regulated by CheA3, the central processor within the Che3 system ofM. xanthus. To our knowledge, this study provides the first example of an ACF chemosensory system regulating a prototypical two-component system and extends our understanding of complex regulation of developmental signaling pathways.

Are Polyphosphoinositides Involved in Signal Transduction of Elicitor-Induced Phytoalexin Synthesis in Cultured Plant Cells ?

1986 ◽  
Vol 41 (7-8) ◽  
pp. 717-724 ◽  
Author(s):  
Heiner Strasser ◽  
Christina Hoffmann ◽  
Hans Grisebach ◽  
Ulrich Matern
Keyword(s):  
Signal Transduction ◽  
Significant Influence ◽  
Plant Cells ◽  
Two Dimensional ◽  
Phytoalexin Synthesis

Abstract The phospholipids of cultured parsley and soybean cells were labelled with myo-[2-3H]inositol, [2-3H]glycerol or [32P]orthophosphate. By one-and two-dimensional chromatographic comparison of the labelled phospholipids with reference substances, the presence of 1-(3-sn-phosphatidyl)-ᴅ-myo-inositol 4-phosphate and 1-(3-sn-phosphatidyl)-ᴅ-myo-inositol 4,5-bisphosphate was demonstrated in these cultures. These results were corroborated by analysis of the deacylation products. Cells were labelled with either myo-[2-3H]inositol, [2-3H]glycerol or [32P]orthophosphate and subsequently challenged with elicitor for various lengths of time. Radioactivity in individual phosphoinositides from these cells was determined. No significant influence of elicitor-challenge of either soybean or parsley cells on incorporation of 3H or 32P into polyphospho­inositides was found between 0.5 and 20 min after elicitor addition.

scholarly journals M177. THE PROTEOME OF OLIGODENDROCYTES DIFFERENTIATED FROM NEURAL STEM CELL DERIVED FROM SCHIZOPHRENIA PATIENTS

2020 ◽  
Vol 46 (Supplement_1) ◽  
pp. S204-S204
Author(s):  
Caroline Teles Rodrigues ◽  
Daniel Martins-De-Souza
Keyword(s):  
Quality Of Life ◽  
Signal Transduction ◽  
Stem Cells ◽  
Two Dimensional ◽  
Rna Transport ◽  
Differentially Expressed Proteins ◽  
Functional Studies ◽  
Canonical Pathways ◽  
Biochemical Mechanisms

Abstract Background Oligodendrocytes constitute the majority of the cells in white matter and alterations in this region have been reported in patients with schizophrenia. The myelin sheath is produced exclusively by mature oligodendrocytes. Thus, a dysfunction during the maturation of these cells could lead to a change in normal myelination processes, causing the hypomyelination observed in patients with schizophrenia. In this manner, functional studies are needed for a better connection of these different aspects of the disease in order to understand the pathophysiology of schizophrenia in an integrated manner. Thus, our aim was to evaluate the differences between the proteome of oligodendrocytes derived from neural stem cells (NSCs) from patients with schizophrenia and controls. Methods The cells were differentiated using the protocol described by Yan, Shin, Jha and collaborators (Yan, Shin, Jha, et al., 2013). After 14 days, the proteins were extracted and proteomic analyses were performed in a two-dimensional microUPLC coupled to nano ESI-Q-IM-TOF mass spectrometer. Progenesis® QI software was used in order to identify and quantify the proteins. Results On average, 2046 proteins were identified and 444 had alterations in the expression levels. These differentially expressed proteins were related most with metabolism, RNA transport, spliceosome machinery, vesicular transport, and signal transduction. Discussion The proteins and canonical pathways found here may contribute to understanding the biochemical mechanisms involved in the disorder, which may provide new targets for the development of more effective treatments, improving the schizophrenic patient’s quality of life.

Cannabis-induced cytotoxicity in leukemic cell lines: the role of the cannabinoid receptors and the MAPK pathway

Blood ◽  
2005 ◽  
Vol 105 (3) ◽  
pp. 1214-1221 ◽  
Author(s):  
Thomas Powles ◽  
Robert te Poele ◽  
Jonathan Shamash ◽  
Tracy Chaplin ◽  
David Propper ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Cell Death ◽  
Cell Lines ◽  
Leukemic Cell ◽  
Cytotoxic Agents ◽  
Complex Signal ◽  
Signal Transduction Pathways ◽  
Potent Inducer ◽  
Leukemic Cell Lines

Abstract Δ9-Tetrahydrocannabinol (THC) is the active metabolite of cannabis. THC causes cell death in vitro through the activation of complex signal transduction pathways. However, the role that the cannabinoid 1 and 2 receptors (CB1-R and CB2-R) play in this process is less clear. We therefore investigated the role of the CB-Rs in mediating apoptosis in 3 leukemic cell lines and performed microarray and immunoblot analyses to establish further the mechanism of cell death. We developed a novel flow cytometric technique of measuring the expression of functional receptors and used combinations of selective CB1-R and CB2-R antagonists and agonists to determine their individual roles in this process. We have shown that THC is a potent inducer of apoptosis, even at 1 × IC50 (inhibitory concentration 50%) concentrations and as early as 6 hours after exposure to the drug. These effects were seen in leukemic cell lines (CEM, HEL-92, and HL60) as well as in peripheral blood mononuclear cells. Additionally, THC did not appear to act synergistically with cytotoxic agents such as cisplatin. One of the most intriguing findings was that THC-induced cell death was preceded by significant changes in the expression of genes involved in the mitogen-activated protein kinase (MAPK) signal transduction pathways. Both apoptosis and gene expression changes were altered independent of p53 and the CB-Rs.

Assembly of an MCP receptor, CheW, and kinase CheA complex in the bacterial chemotaxis signal transduction pathway

Cell ◽  
1992 ◽  
Vol 70 (6) ◽  
pp. 975-982 ◽  
Author(s):  
Julie A. Gegner ◽  
Daniel R. Graham ◽  
Amy F. Roth ◽  
Frederick W. Dahlquist
Keyword(s):  
Signal Transduction ◽  
Bacterial Chemotaxis ◽  
Signal Transduction Pathway ◽  
Transduction Pathway
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