scholarly journals Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

2018 ◽  
Vol 14 ◽  
pp. 1769-1777 ◽  
Author(s):  
Bimal Koirala ◽  
Robert A Hillman ◽  
Erin K Tiwold ◽  
Michael A Bertucci ◽  
Yftah Tal-Gan
Keyword(s):  
Streptococcus Pneumoniae ◽  
Hydrophobic Interactions ◽  
Point Mutations ◽  
Cell Communication ◽  
Cell Number ◽  
Chronic Infections ◽  
Drug Candidates ◽  
A Cell ◽  
Natural Amino Acids ◽  
Protease Degradation

Quorum sensing (QS) is a cell–cell communication mechanism that enables bacteria to assess their population density and alter their behavior upon reaching high cell number. Many bacterial pathogens utilize QS to initiate an attack on their host, thus QS has attracted significant attention as a potential antivirulence alternative to traditional antibiotics. Streptococcus pneumoniae, a notorious human pathogen responsible for a variety of acute and chronic infections, utilizes the competence regulon and its associated signaling peptide, the competence stimulating peptide (CSP), to acquire antibiotic resistance and establish an infection. In this work, we sought to define the binding pockets within the ComD1 receptor used for binding the hydrophobic side-chain residues in CSP1 through the introduction of highly-conservative point mutations within the peptide. Optimization of these binding interactions could lead to the development of highly potent CSP-based QS modulators while the inclusion of non-natural amino acids within the CSP sequence would confer resistance to protease degradation, a requirement for drug candidates.

scholarly journals The function of the Drosophila fat facets deubiquitinating enzyme in limiting photoreceptor cell number is intimately associated with endocytosis

Development ◽  
2000 ◽  
Vol 127 (8) ◽  
pp. 1727-1736 ◽  
Author(s):  
A.L. Cadavid ◽  
A. Ginzel ◽  
J.A. Fischer
Keyword(s):  
Compound Eye ◽  
Cell Communication ◽  
Photoreceptor Cells ◽  
Cell Number ◽  
Deubiquitinating Enzyme ◽  
A Cell ◽  
Fat Facets ◽  
Liquid Facets ◽  
And Function ◽  
Communication Pathway

Fat facets is a deubiquitinating enzyme required in a cell communication pathway that limits to eight the number of photoreceptor cells in each facet of the Drososphila compound eye. Genetic data support a model whereby Faf removes ubiquitin, a polypeptide tag for protein degradation, from a specific ubiquitinated protein thus preventing its degradation. Here, mutations in the liquid facets gene were identified as dominant enhancers of the fat facets mutant eye phenotype. The liquid facets locus encodes epsin, a vertebrate protein associated with the clathrin endocytosis complex. The results of genetic experiments reveal that fat facets and liquid facets facilitate endocytosis and function in common cells to generate an inhibitory signal that prevents ectopic photoreceptor determination. Moreover, it is demonstrated that the fat facets mutant phenotype is extraordinarily sensitive to the level of liquid facets expression. We propose that Liquid facets is a candidate for the critical substrate of Fat facets in the eye.

Coaction of Electrostatic and Hydrophobic Interactions: Dynamic Constraints on Disordered TrkA Juxtamembrane Domain

2019 ◽  
Author(s):  
Zichen Wang ◽  
Huaxun Fan ◽  
Xiao Hu ◽  
John Khamo ◽  
Jiajie Diao ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Function ◽  
Hydrophobic Interactions ◽  
Transmembrane Helix ◽  
Point Mutations ◽  
Salt Bridge ◽  
Receptor Activation ◽  
Membrane Dynamics ◽  
Juxtamembrane Domain ◽  
Joint Work

<p>The receptor tyrosine kinase family transmits signals into cell via a single transmembrane helix and a flexible juxtamembrane domain (JMD). Membrane dynamics makes it challenging to study the structural mechanism of receptor activation experimentally. In this study, we employ all-atom molecular dynamics with Highly Mobile Membrane-Mimetic to capture membrane interactions with the JMD of tropomyosin receptor kinase A (TrkA). We find that PIP<sub>2 </sub>lipids engage in lasting binding to multiple basic residues and compete with salt bridge within the peptide. We discover three residues insertion into the membrane, and perturb it through computationally designed point mutations. Single-molecule experiments indicate the contribution from hydrophobic insertion is comparable to electrostatic binding, and in-cell experiments show that enhanced TrkA-JMD insertion promotes receptor ubiquitination. Our joint work points to a scenario where basic and hydrophobic residues on disordered domains interact with lipid headgroups and tails, respectively, to restrain flexibility and potentially modulate protein function.</p>

scholarly journals Analysis of the RNA content of the exosomes derived from blood serum and urine and its potential as biomarkers

2014 ◽  
Vol 369 (1652) ◽  
pp. 20130502 ◽  
Author(s):  
Mu Li ◽  
Emily Zeringer ◽  
Timothy Barta ◽  
Jeoffrey Schageman ◽  
Angie Cheng ◽  
...  
Keyword(s):  
Blood Serum ◽  
Cell Communication ◽  
Cell Culture Model ◽  
Culture Model ◽  
Wide Range ◽  
Abnormal Cells ◽  
A Cell ◽  
Invasive Diagnostics ◽  
Serum And Urine

Exosomes are tiny vesicles (30–150 nm) constantly secreted by all healthy and abnormal cells, and found in abundance in all body fluids. These vesicles, loaded with unique RNA and protein cargo, have a wide range of biological functions, including cell-to-cell communication and signalling. As such, exosomes hold tremendous potential as biomarkers and could lead to the development of minimally invasive diagnostics and next generation therapies within the next few years. Here, we describe the strategies for isolation of exosomes from human blood serum and urine, characterization of their RNA cargo by sequencing, and present the initial data on exosome labelling and uptake tracing in a cell culture model. The value of exosomes for clinical applications is discussed with an emphasis on their potential for diagnosing and treating neurodegenerative diseases and brain cancer.

Microglia extracellular vesicles: focus on molecular composition and biological function

2021 ◽  
Vol 49 (4) ◽  
pp. 1779-1790 ◽  
Author(s):  
Lorenzo Ceccarelli ◽  
Chiara Giacomelli ◽  
Laura Marchetti ◽  
Claudia Martini
Keyword(s):  
Extracellular Vesicles ◽  
Molecular Mechanisms ◽  
Biological Function ◽  
Biological Effects ◽  
Genetic Material ◽  
Cell Communication ◽  
Molecular Composition ◽  
Cargo Proteins ◽  
A Cell ◽  
The Central Nervous System

Extracellular vesicles (EVs) are a heterogeneous family of cell-derived lipid bounded vesicles comprising exosomes and microvesicles. They are potentially produced by all types of cells and are used as a cell-to-cell communication method that allows protein, lipid, and genetic material exchange. Microglia cells produce a large number of EVs both in resting and activated conditions, in the latter case changing their production and related biological effects. Several actions of microglia in the central nervous system are ascribed to EVs, but the molecular mechanisms by which each effect occurs are still largely unknown. Conflicting functions have been ascribed to microglia-derived EVs starting from the neuronal support and ending with the propagation of inflammation and neurodegeneration, confirming the crucial role of these organelles in tuning brain homeostasis. Despite the increasing number of studies reported on microglia-EVs, there is also a lot of fragmentation in the knowledge on the mechanism at the basis of their production and modification of their cargo. In this review, a collection of literature data about the surface and cargo proteins and lipids as well as the miRNA content of EVs produced by microglial cells has been reported. A special highlight was given to the works in which the EV molecular composition is linked to a precise biological function.

CD40 LIGAND MUTATIONS IN X-LINKED IMMUNODEFICIENCY WITH HYPER-IgM

PEDIATRICS ◽  
1994 ◽  
Vol 94 (2) ◽  
pp. 280-280
Author(s):  
Arden Levy ◽  
Andrew Liu
Keyword(s):  
T Cells ◽  
B Cells ◽  
Bacterial Infections ◽  
Point Mutations ◽  
Cell Communication ◽  
Cd40 Ligand ◽  
Research Groups ◽  
Immune Disorder ◽  
Hyper Igm

Purpose of the Studies. Hyper-IgM immunodeficiency is characterized by recurrent bacterial infections, normal or elevated IgM, and markedly decreased IgG, IgA, and IgE. Previous research suggested that the T cells of these patients are defective in their ability to help B cells make functional antibody. CD40 ligand (CD4OL) is a membrane glycoprotein on activated T helper cells and binds the CD40 molecule expressed on B cells, and induces proliferation and immunoglobulin class switching (in conjunction with IL-4). The gene for the CD4OL has been mapped to position q26.3-q27.1 on chromosome X (same as the Hyper-IgM gene and the area of isotype switching). Several research groups sought to determine if the immunodeficiency in Hyper-IgM patients is due to defective CD4OL. Findings. The five papers listed above document the work of different research groups that simultaneously found abnormalities in the CD4OL gene in a total of 16 patients with X-linked Hyper-IgM syndrome. Different mutations of the CD4OL gene have been discovered, including point mutations, deletions, and nonsense sequences. Mutant version of CD4OL taken from Hyper IgM patients were unable to "help" B cells in vitro. Thus, deficient CD40/CD40L interactions between B and T cells results in severely impaired immunity. Restricted CD40L gene expression to T cells may ultimately allow gene therapy as treatment. Reviewers' Comments. A concise editorial by Jean Marx entitled "Cell Communication Failure Leads to Immune Disorder" describes this landmark research and accompanies the Spriggs article in the February 12th issue of Science (pp. 896-897). This discovery may not only lead to treatment of this disorder, but also modification of other less favorable immune responses.

Development of the Drosophila olfactory sense organs utilizes cell-cell interactions as well as lineage

Development ◽  
1997 ◽  
Vol 124 (3) ◽  
pp. 703-712 ◽  
Author(s):  
G.V. Reddy ◽  
B. Gupta ◽  
K. Ray ◽  
V. Rodrigues
Keyword(s):  
Cell Communication ◽  
Cell Number ◽  
Temperature Sensitive ◽  
Sense Organs ◽  
Notch Activity ◽  
Helix Loop Helix ◽  
Olfactory Sense ◽  
Sensitive Allele ◽  
Selection Of ◽  
Cell Cell

We have examined the mechanisms underlying the development of the olfactory sense organs on the third segment of the antenna of Drosophila. Our studies suggest that a novel developmental strategy is employed. Specification of the founder or precursor cell is not governed by the genes of the achaete-scute complex. Another basic helix-loop-helix encoding gene, atonal, is essential for determination of only a subset of the sensilla types--the sensilla coeloconica. Therefore, we predict the existence of additional proneural genes for the selection of sensilla trichoidea and sensilla basiconica. The choice of a founder cell from the presumed proneural domain is regulated by Notch activity. Soon after delamination of the founder cell, two to three additional neighboring cells also take on a sensory fate and these cells together form a presensillum cluster. The selection of neighbors does not occur when endocytosis is blocked using a temperature sensitive allele of shibire, thus suggesting that cell-cell communication is required for this step. The cells of the cluster divide once before terminal differentiation which is influenced by Notch activity. The final cell number within each sensillum is controlled by programmed cell death.

scholarly journals Medicinal Leech CNS as a Model for Exosome Studies in the Crosstalk between Microglia and Neurons

2018 ◽  
Vol 19 (12) ◽  
pp. 4124 ◽  
Author(s):  
Antonella Raffo-Romero ◽  
Tanina Arab ◽  
Issa Al-Amri ◽  
Francoise Le Marrec-Croq ◽  
Christelle Van Camp ◽  
...  
Keyword(s):  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Present Report ◽  
Primary Cultures ◽  
Cell Communication ◽  
Medicinal Leech ◽  
Neuronal Cultures ◽  
Primary Neuronal Cultures ◽  
A Cell

In healthy or pathological brains, the neuroinflammatory state is supported by a strong communication involving microglia and neurons. Recent studies indicate that extracellular vesicles (EVs), including exosomes and microvesicles, play a key role in the physiological interactions between cells allowing central nervous system (CNS) development and/or integrity. The present report used medicinal leech CNS to investigate microglia/neuron crosstalk from ex vivo approaches as well as primary cultures. The results demonstrated a large production of exosomes from microglia. Their incubation to primary neuronal cultures showed a strong interaction with neurites. In addition, neurite outgrowth assays demonstrated microglia exosomes to exhibit significant neurotrophic activities using at least a Transforming Growth Factor beta (TGF-β) family member, called nGDF (nervous Growth/Differentiation Factor). Of interest, the results also showed an EV-mediated dialog between leech microglia and rat cells highlighting this communication to be more a matter of molecules than of species. Taken together, the present report brings a new insight into the microglia/neuron crosstalk in CNS and would help deciphering the molecular evolution of such a cell communication in brain.

scholarly journals Hypoxia triggers collective aerotactic migration in Dictyostelium discoideum

2020 ◽  
Author(s):  
O. Cochet-Escartin ◽  
M. Demircigil ◽  
S. Hirose ◽  
B. Allais ◽  
P. Gonzalo ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Communication ◽  
Quantitative Agreement ◽  
Cellular Potts Model ◽  
Detection Mechanism ◽  
Cell Behaviors ◽  
Dense Ring ◽  
Efficient Detection ◽  
Technological Developments ◽  
A Cell

AbstractIt is well known that eukaryotic cells can sense oxygen (O2) and adapt their metabolism accordingly. It is less known that they can also move towards regions of higher oxygen level (aerotaxis). Using a self-generated hypoxic assay, we show that the social amoeba Dictyostelium discoideum displays a spectacular aerotactic behavior. When a cell colony is covered by a coverglass, cells quickly consume the available O2 and the ones close to the periphery move directionally outward forming a dense ring keeping a constant speed and density. To confirm that O2 is the main molecular player in this seemingly collective process, we combined two technological developments, porphyrin based O2 sensing films and microfluidic O2 gradient generators. We showed that Dictyostelium cells exhibit aerotactic and aerokinetic (increased speed at low O2) response in an extremely low range of O2 concentration (0-1.5%) indicative of a very efficient detection mechanism. The various cell behaviors under self-generated or imposed O2 gradients were modeled with a very satisfactory quantitative agreement using an in silico cellular Potts model built on experimental observations. This computational model was complemented with a parsimonious ‘Go or Grow’ partial differential equation (PDE) model. In both models, we found that the collective migration of a dense ring can be explained by the interplay between cell division and the modulation of aerotaxis, without the need for cell-cell communication.

scholarly journals Cell-Tak coating may cause mis-normalization of Seahorse metabolic flux data

2021 ◽  
Author(s):  
Michal Šíma ◽  
Stanislava Martínková ◽  
Anežka Kafková ◽  
Jan Pala ◽  
Jan Trnka
Keyword(s):  
Metabolic Flux ◽  
Cell Number ◽  
Cell Counting ◽  
Fluorescent Detection ◽  
Data Normalization ◽  
Tissue Samples ◽  
Flux Data ◽  
Research Areas ◽  
Healthy State ◽  
A Cell

Metabolic flux investigations of cells and tissue samples are a rapidly advancing tool in diverse research areas. Reliable methods of data normalization are crucial for an adequate interpretation of results and to avoid a misinterpretation of experiments and incorrect conclusions. The most common methods for metabolic flux data normalization are to cell number, DNA and protein. Data normalization may be affected by a variety of factors, such as density, healthy state, adherence efficiency, or proportional seeding of cells. The mussel-derived adhesive Cell-Tak is often used to immobilize poorly adherent cells. Here we demonstrate that this coating may strongly affect the fluorescent detection of DNA leading to an incorrect and highly variable normalization of metabolic flux data. Protein assays are much less affected and cell counting can virtually completely remove the effect of the coating. Cell-Tak coating also affects cell shape in a cell line-specific manner and may change cellular metabolism. Based on these observations we recommend cell counting as a gold standard normalization method for Seahorse metabolic flux measurements with protein content as a reasonable alternative.

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