scholarly journals Directing Min protein patterns with advective bulk flow

2021 ◽  
Author(s):  
Sabrina Meindlhumer ◽  
Fridtjof Brauns ◽  
Jernej Rudi Finžgar ◽  
Jacob Kerssemakers ◽  
Cees Dekker ◽  
...  
Keyword(s):  
Flow Direction ◽  
Membrane Surface ◽  
Coupled Systems ◽  
Bulk Flow ◽  
Control Surface ◽  
Surface Pattern ◽  
Bulk Solution ◽  
Protein Patterns ◽  
Molecular Features

We theoretically predict and experimentally show that the propagation direction of in vitro Min protein patterns can be controlled by a hydrodynamic flow of the bulk solution. We find downstream propagation of Min wave patterns relative to the bulk flow direction for low MinE:MinD concentration ratios, but upstream propagation for large MinE:MinD ratios, with multistability of both propagation directions in between. A theoretical model for the Min system reveals the mechanism underlying the upstream propagation and links it to the fast conformational switching of MinE in the bulk. For high MinE:MinD ratios, upstream propagation can be reproduced by a reduced model in which increased MinD bulk concentrations on the upstream side promote protein attachment and hence, propagation in that direction. For low MinE:D ratios, downstream propagation is described by the minimal model, as additionally confirmed by experiments with a non-switching MinE mutant. No advection takes place on the membrane surface where the protein patterns form, but advective bulk flow shifts the protein-concentration profiles in the bulk relative to the membrane-bound pattern. From a broader perspective, differential flows in a bulk volume relative to a surface are a relevant general feature in bulk-surface coupled systems. Our study shows how such a differential flow can control surface-pattern propagation and demonstrates how the global pattern's response may depend on specific molecular features of the reaction kinetics.

scholarly journals Bulk-surface coupling reconciles Min-protein pattern formation in vitro and in vivo

2020 ◽  
Author(s):  
Fridtjof Brauns ◽  
Grzegorz Pawlik ◽  
Jacob Halatek ◽  
Jacob Kerssemakers ◽  
Erwin Frey ◽  
...  
Keyword(s):  
Protein Pattern ◽  
Oscillation Mode ◽  
Coupled Systems ◽  
Protein Patterns ◽  
Spatial Control ◽  
Bulk Surface ◽  
Oscillation Modes ◽  
Min Proteins

AbstractSelf-organisation of Min proteins is responsible for the spatial control of cell division in Escherichia coli, and has been studied both in vivo and in vitro. Intriguingly, the protein patterns observed in these settings differ qualitatively and quantitatively. This puzzling dichotomy has not been resolved to date. Using reconstituted proteins in laterally wide microchambers with a well-controlled height, we show that the Min protein dynamics on the membrane crucially depend on bulk gradients normal to the membrane. A theoretical analysis shows that in vitro patterns at low bulk height are driven by the same lateral oscillation mode as pole-to-pole oscillations in vivo. At larger bulk height, additional vertical oscillation modes set in, marking the transition to a qualitatively different in vitro regime. Our work qualitatively resolves the Min system’s in vivo/in vitro conundrum and provides important insights on the mechanisms underlying protein patterns in bulk-surface coupled systems.

Transport of purine nucleotides and nucleosides by in vitro rabbit ileum.

1977 ◽  
Vol 233 (1) ◽  
pp. E47 ◽  
Author(s):  
V Harms ◽  
C E Stirling
Keyword(s):  
Epithelial Cells ◽  
Membrane Surface ◽  
Bulk Solution ◽  
Purine Nucleotides ◽  
Rabbit Ileum ◽  
Structural Requirements ◽  
Nucleotides And Nucleosides ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of [14C]ATP and [14C]adenosine entry into rabbit ileum were measured using 1-min mucosal exposures. ATP influx was the sum of a linear (P = 1.02 X 10(-3) cm/min) and nonlinear component (Jm = 4.07 nmol/min cm2, Km = 0.31 mM). Adenosine yielded quantitatively similar results. The kinetics of [gamma-32P]ATP entry were only linear (P = 0.55 X 10(-3) cm/min). These data indicate that at least 85% of the terminal phosphate of ATP is hydrolyzed during transport. Inhibitory measurements indicate that ring-labeled ATP and adenosine compete for a common entry path; however, adenosine does not inhibit the saturable component of [14C]ATP to the degree expected of a simple carrier-mediated system. Adenosine (5 mM) produced no inhibition of [gamma-32P]ATP (0.1-1.0 mM) entry. Measurement of hydrolysis during incubation indicates a negligible fraction of uptake results from labeled adenosine released into the bulk solution. Hydrolysis of ATP followed by a preferred uptake of the adenosine released at the membrane surface probably accounts for most of the observed transport. [14C]ATP entry depended neither on [Na+], [Mg2+], nor [Ca2+] of the bulk solution. Structural requirements for the saturable pathway were also investigated. Autoradiography of [3H]ATP confirmed that the labeled material entered the epithelial cells and that uptake was nonuniform among cells.

scholarly journals Interaction of Aβ42 with Membranes Triggers the Self-Assembly into Oligomers

2020 ◽  
Vol 21 (3) ◽  
pp. 1129 ◽  
Author(s):  
Siddhartha Banerjee ◽  
Mohtadin Hashemi ◽  
Karen Zagorski ◽  
Yuri L. Lyubchenko
Keyword(s):  
Self Assembly ◽  
Membrane Surface ◽  
Amyloid Β ◽  
The Self ◽  
Bulk Solution ◽  
Aggregation Process ◽  
Physiological Concentration ◽  
Dynamics Simulations

The self-assembly of amyloid β (Aβ) proteins into oligomers is the major pathogenic event leading to Alzheimer’s disease (AD). Typical in vitro experiments require high protein concentrations, whereas the physiological concentration of Aβ is in the picomolar to low nanomolar range. This complicates the translation of results obtained in vitro to understanding the aggregation process in vivo. Here, we demonstrate that Aβ42 self-assembles into aggregates on membrane bilayers at low nanomolar concentrations - a pathway in which the membrane plays the role of a catalyst. Additionally, physiological ionic conditions (150 mM NaCl) significantly enhance on-membrane aggregation, leading to the rapid formation of oligomers. The self-assembly process is reversible, so assembled aggregates can dissociate from the membrane surface into the bulk solution to further participate in the aggregation process. Molecular dynamics simulations demonstrate that the transient membrane-Aβ interaction dramatically changes the protein conformation, facilitating the assembly of dimers. The results indicate peptide–membrane interaction is the critical step towards oligomer formation at physiologically low protein concentrations.

scholarly journals Stochastic activation and bistability in a Rab GTPase regulatory network

2020 ◽  
Vol 117 (12) ◽  
pp. 6540-6549
Author(s):  
Urban Bezeljak ◽  
Hrushikesh Loya ◽  
Beata Kaczmarek ◽  
Timothy E. Saunders ◽  
Martin Loose
Keyword(s):  
Regulatory Network ◽  
Regulatory Networks ◽  
Membrane Surface ◽  
Activity Patterns ◽  
Small Gtpases ◽  
Signaling Networks ◽  
Rab Gtpase ◽  
Endomembrane System ◽  
In Vitro Reconstitution

The eukaryotic endomembrane system is controlled by small GTPases of the Rab family, which are activated at defined times and locations in a switch-like manner. While this switch is well understood for an individual protein, how regulatory networks produce intracellular activity patterns is currently not known. Here, we combine in vitro reconstitution experiments with computational modeling to study a minimal Rab5 activation network. We find that the molecular interactions in this system give rise to a positive feedback and bistable collective switching of Rab5. Furthermore, we find that switching near the critical point is intrinsically stochastic and provide evidence that controlling the inactive population of Rab5 on the membrane can shape the network response. Notably, we demonstrate that collective switching can spread on the membrane surface as a traveling wave of Rab5 activation. Together, our findings reveal how biochemical signaling networks control vesicle trafficking pathways and how their nonequilibrium properties define the spatiotemporal organization of the cell.

scholarly journals Bone Marrow Mesenchymal Stromal Cells on Silk Fibroin Scaffolds to Attenuate Polymicrobial Sepsis Induced by Cecal Ligation and Puncture

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1433
Author(s):  
Ok-Hyeon Kim ◽  
Jun-Hyung Park ◽  
Jong-In Son ◽  
Ok-Ja Yoon ◽  
Hyun-Jung Lee
Keyword(s):  
Bone Marrow ◽  
Cecal Ligation ◽  
Biological Properties ◽  
Pge2 Production ◽  
Polymicrobial Sepsis ◽  
Control Surface ◽  
Related Factors ◽  
Cox 2 ◽  
Anti Inflammatory

Suitable scaffolds with appropriate mechanical and biological properties can improve mesenchymal stromal cell (MSC) therapy. Because silk fibroins (SFs) are biocompatible materials, they were electrospun and applied as scaffolds for MSC therapy. Consequently, interferon (IFN)-primed human bone marrow MSCs on SF nanofibers were administered into a polymicrobial sepsis murine model. The IL-6 level gradually decreased from 40 ng/mL at 6 h after sepsis to 35 ng/mL at 24 h after sepsis. The IL-6 level was significantly low as 5 ng/mL in primed MSCs on SF nanofibers, and 15 ng/mL in primed MSCs on the control surface. In contrast to the acute response, inflammation-related factors, including HO-1 and COX-2 in chronic liver tissue, were effectively inhibited by MSCs on both SF nanofibers and the control surface at the 5-day mark after sepsis. An in vitro study indicated that the anti-inflammatory function of MSCs on SF nanofibers was mediated through enhanced COX-2-PGE2 production, as indomethacin completely abrogated PGE2 production and decreased the survival rate of septic mice. Thus, SF nanofiber scaffolds potentiated the anti-inflammatory and immunomodulatory functions of MSCs, and were beneficial as a culture platform for the cell therapy of inflammatory disorders.

scholarly journals Chromatography-Independent Fractionation and Newly Identified Molecular Features of the Adzuki Bean (Vigna angularis Willd.) β-vignin Protein

2021 ◽  
Vol 22 (6) ◽  
pp. 3018
Author(s):  
Biane Philadelpho ◽  
Victória Souza ◽  
Fabiani Souza ◽  
Johnnie Santos ◽  
Fabiana Batista ◽  
...  
Keyword(s):  
Metal Binding ◽  
Cardiovascular Health ◽  
Binding Capacity ◽  
Biological Activities ◽  
Electrophoretic Analysis ◽  
Adzuki Bean ◽  
Molecular Features ◽  
Health Promoting ◽  
High Degree

Adzuki seed β-vignin, a vicilin-like globulin, has proven to exert various health-promoting biological activities, notably in cardiovascular health. A simple scalable enrichment procedure of this protein for further nutritional and functional studies is crucial. In this study, a simplified chromatography-independent protein fractionation procedure has been optimized and described. The electrophoretic analysis showed a high degree of homogeneity of β-vignin isolate. Furthermore, the molecular features of the purified protein were investigated. The adzuki bean β-vignin was found to have a native size of 146 kDa, and the molecular weight determined was consistent with a trimeric structure. These were identified in two main polypeptide chains (masses of 56–54 kDa) that are glycosylated polypeptides with metal binding capacity, and one minor polypeptide chain with a mass 37 kDa, wherein these features are absent. The in vitro analysis showed a high degree of digestibility of the protein (92%) and potential anti-inflammatory capacity. The results lay the basis not only for further investigation of the health-promoting properties of the adzuki bean β-vignin protein, but also for a possible application as nutraceutical molecule.

scholarly journals Context-Specific Efficacy of Apalutamide Therapy in Preclinical Models of Pten-Deficient Prostate Cancer

Cancers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 3975
Author(s):  
Marco A. De Velasco ◽  
Yurie Kura ◽  
Naomi Ando ◽  
Noriko Sako ◽  
Eri Banno ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Antitumor Activity ◽  
Cancer Cells ◽  
Late Stage ◽  
Early Stage ◽  
Castration Resistant Prostate Cancer ◽  
Akt Inhibitor ◽  
Molecular Features ◽  
Context Specific

Significant improvements with apalutamide, a nonsteroidal antiandrogen used to treat patients suffering from advanced prostate cancer (PCa), have prompted evaluation for additional indications and therapeutic development with other agents; however, persistent androgen receptor (AR) signaling remains problematic. We used autochthonous mouse models of Pten-deficient PCa to examine the context-specific antitumor activity of apalutamide and profile its molecular responses. Overall, apalutamide showed potent antitumor activity in both early-stage and late-stage models of castration-naïve prostate cancer (CNPC). Molecular profiling by Western blot and immunohistochemistry associated persistent surviving cancer cells with upregulated AKT signaling. While apalutamide was ineffective in an early-stage model of castration-resistant prostate cancer (CRPC), it tended to prolong survival in late-stage CRPC. Molecular features associated with surviving cancer cells in CRPC included upregulated aberrant-AR, and phosphorylated S6 and proline-rich Akt substrate of 40 kDa (PRAS40). Strong synergy was observed with the pan-AKT inhibitor GSK690693 and apalutamide in vitro against the CNPC- and CRPC-derived cell lines and tended to improve the antitumor responses in CNPC but not CRPC in vivo. Upregulation of signal transducer and activator of transcription 3 (STAT3) and proviral insertion in murine-1 (PIM-1) were associated with combined apalutamide/GSK690693. Our findings show that apalutamide can attenuate Pten-deficient PCa in a context-specific manner and provides data that can be used to further study and, possibly, develop additional combinations with apalutamide.

scholarly journals Isolation and characterization of Pseudomonas syringae isolates affecting stone fruits and almond in Montenegro

2021 ◽  
Author(s):  
Tamara Popović ◽  
Jelena Menković ◽  
Anđelka Prokić ◽  
Nevena Zlatković ◽  
Aleksa Obradović
Keyword(s):  
Pseudomonas Syringae ◽  
Housekeeping Genes ◽  
Molecular Characteristics ◽  
Biochemical Tests ◽  
High Genetic Diversity ◽  
Leaf Petiole ◽  
Molecular Features ◽  
Isolation And Characterization ◽  
Genomic Species

AbstractIn Montenegro, stone fruit species are grown on intensive and semi-intensive commercial plantations. However, almond production is mainly organized on family gardens and for household consumption. During two seasons (2017–2018), we surveyed apricot, peach, nectarine, sweet cherry, Japanese plum, and almond orchards for the presence of bacterial diseases at different geographical locations in Montenegro. From leaf, petiole and fruit lesions, branch or twig cankers, and necrotizing buds, a total of 29 isolates were obtained and subjected to identification based on their morphological, pathogenic, biochemical, and molecular characteristics. Pathogenicity of the isolates was confirmed by reproducing the symptoms on leaves, fruits, and twigs of the corresponding host plants. The biochemical tests indicated that the isolates belong to Pseudomonas syringae. However, isolates’ characterization showed variation in their phenotypic and molecular features. The presence of the syrB gene and ice nucleation activity grouped most of the isolates within pathovar syringae. The results of rep-PCR using the BOX primer revealed high genetic diversity of isolates. Multilocus sequence analysis (MLSA), using four housekeeping genes, showed that 27 isolates belong to the genomic species 1, P. syringae sensu stricto, corresponding to P. syringae phylogroup 2. However, isolates from the same phylogroup 2 did not form a monophyletic group. One strain isolated from apricot was most distinct and similar to members of genomic species 2, phylogroup 3. All tested isolates showed significant levels of resistance to copper sulfate and high level of sensitivity to streptomycin sulfate in vitro.

scholarly journals Extracellular Vesicles Are More Potent Than Adipose Mesenchymal Stromal Cells to Exert an Anti-Fibrotic Effect in an In Vitro Model of Systemic Sclerosis

2021 ◽  
Vol 22 (13) ◽  
pp. 6837
Author(s):  
Pauline Rozier ◽  
Marie Maumus ◽  
Claire Bony ◽  
Alexandre Thibault Jacques Maria ◽  
Florence Sabatier ◽  
...  
Keyword(s):  
Systemic Sclerosis ◽  
Extracellular Vesicles ◽  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
In Vitro Model ◽  
Specific Treatment ◽  
Complex Disorder ◽  
Molecular Features ◽  
Vitro Model

Systemic sclerosis (SSc) is a complex disorder resulting from dysregulated interactions between the three main pathophysiological axes: fibrosis, immune dysfunction, and vasculopathy, with no specific treatment available to date. Adipose tissue-derived mesenchymal stromal cells (ASCs) and their extracellular vesicles (EVs) have proved efficacy in pre-clinical murine models of SSc. However, their precise action mechanism is still not fully understood. Because of the lack of availability of fibroblasts isolated from SSc patients (SSc-Fb), our aim was to determine whether a TGFβ1-induced model of human myofibroblasts (Tβ-Fb) could reproduce the characteristics of SSc-Fb and be used to evaluate the anti-fibrotic function of ASCs and their EVs. We found out that Tβ-Fb displayed the main morphological and molecular features of SSc-Fb, including the enlarged hypertrophic morphology and expression of several markers associated with the myofibroblastic phenotype. Using this model, we showed that ASCs were able to regulate the expression of most myofibroblastic markers on Tβ-Fb and SSc-Fb, but only when pre-stimulated with TGFβ1. Of interest, ASC-derived EVs were more effective than parental cells for improving the myofibroblastic phenotype. In conclusion, we provided evidence that Tβ-Fb are a relevant model to mimic the main characteristics of SSc fibroblasts and investigate the mechanism of action of ASCs. We further reported that ASC-EVs are more effective than parental cells suggesting that the TGFβ1-induced pro-fibrotic environment may alter the function of ASCs.

scholarly journals Endothelial-to-Mesenchymal Transition in Human Adipose Tissue Vasculature Alters the Particulate Secretome and Induces Endothelial Dysfunction

2019 ◽  
Vol 39 (10) ◽  
pp. 2168-2191 ◽  
Author(s):  
Bronson A. Haynes ◽  
Li Fang Yang ◽  
Ryan W. Huyck ◽  
Eric J. Lehrer ◽  
Joshua M. Turner ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Endothelial Dysfunction ◽  
Smooth Muscle Actin ◽  
Phenotypic Change ◽  
Alpha Smooth Muscle Actin ◽  
Mesenchymal Transition ◽  
Molecular Features ◽  
Endothelial To Mesenchymal Transition

Objective: Endothelial cells (EC) in obese adipose tissue (AT) are exposed to a chronic proinflammatory environment that may induce a mesenchymal-like phenotype and altered function. The objective of this study was to establish whether endothelial-to-mesenchymal transition (EndoMT) is present in human AT in obesity and to investigate the effect of such transition on endothelial function and the endothelial particulate secretome represented by extracellular vesicles (EV). Approach and Results: We identified EndoMT in obese human AT depots by immunohistochemical co-localization of CD31 or vWF and α-SMA (alpha-smooth muscle actin). We showed that AT EC exposed in vitro to TGF-β (tumor growth factor-β), TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-γ) undergo EndoMT with progressive loss of endothelial markers. The phenotypic change results in failure to maintain a tight barrier in culture, increased migration, and reduced angiogenesis. EndoMT also reduced mitochondrial oxidative phosphorylation and glycolytic capacity of EC. EVs produced by EC that underwent EndoMT dramatically reduced angiogenic capacity of the recipient naïve ECs without affecting their migration or proliferation. Proteomic analysis of EV produced by EC in the proinflammatory conditions showed presence of several pro-inflammatory and immune proteins along with an enrichment in angiogenic receptors. Conclusions: We demonstrated the presence of EndoMT in human AT in obesity. EndoMT in vitro resulted in production of EV that transferred some of the functional and metabolic features to recipient naïve EC. This result suggests that functional and molecular features of EC that underwent EndoMT in vivo can be disseminated in a paracrine or endocrine fashion and may induce endothelial dysfunction in distant vascular beds.

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