Signaling to the actin cytoskeleton

Shedding light on biochemical changes in single neuron-like pheochromocytoma cells following exposure to synchrotron sourced terahertz radiation using synchrotron source Fourier transform infrared microspectroscopy

Synchrotron sourced Fourier transform infrared (SS FTIR) microspectroscopy was employed to investigate the biological effects on the neuron-like pheochromocytoma (PC 12) cells after exposure to synchrotron sourced terahertz (SS THz) radiation. Over 10 min of exposure, the PC 12 cells received a total energy of 600 J m2, with a total incident power density of ∼1.0 W m-2 (0.10 mW cm-2) at the beam extraction port (BEP) of the THz beamline at the Australian Synchrotron. To investigate the metabolic response of PC 12 cells after synchrotron THz radiation exposure, we utilized the FTIR microscope at the Infrared Microspectroscopy IRM beamline, which offers high photon flux and diffraction-limited spatial resolution enabling the detection of functional group variations in biological molecules at a single-cell level. Principal component analysis (PCA) based on the SS FTIR spectral data revealed a distinct separation of SS THz-exposed and control (non-exposed) cells. According to the PCA loadings, the key changes in the exposed cells involved lipid and protein compositions as indicated by the stretching vibrations of CH2/CH3 groups and amide I/II bands, respectively. An increase in lipids, such as cholesterol, or notable changes in their compositions and in some protein secondary structures were observed in the SS THz-exposed cells. The PCA analysis further suggests that PC 12 cells might maintain cell membrane stability after SS THz irradiation through higher volumes of cholesterol and cell morphology via regulation of the synthesis of cytoskeleton proteins such as actin-related proteins. The outcome of this study re-emphasized the exceptional SS FTIR capability to perform single-cell analysis directly, providing (i) unique biological information on cell variability within the population as well as between different groups, and (ii) evidence of molecular changes in the exposed cells that could lead to a deeper understanding of the effect of THz exposure at a single-cell level.

Role of Akt/Protein Kinase B in Cancer Metastasis

Metastasis is a critical step in the process of carcinogenesis and a vast majority of cancer-related mortalities result from metastatic disease that is resistant to current therapies. Cell migration and invasion are the first steps of the metastasis process, which mainly occurs by two important biological mechanisms, i.e., cytoskeletal remodelling and epithelial to mesenchymal transition (EMT). Akt (also known as protein kinase B) is a central signalling molecule of the PI3K-Akt signalling pathway. Aberrant activation of this pathway has been identified in a wide range of cancers. Several studies have revealed that Akt actively engages with the migratory process in motile cells, including metastatic cancer cells. The downstream signalling mechanism of Akt in cell migration depends upon the tumour type, sites, and intracellular localisation of activated Akt. In this review, we focus on the role of Akt in the regulation of two events that control cell migration and invasion in various cancers including head and neck squamous cell carcinoma (HNSCC) and the status of PI3K-Akt pathway inhibitors in clinical trials in metastatic cancers.

Crowding alters F-actin secondary structure and hydration

Actin, an important component of eukaryotic cell cytoskeleton, regulates cell shape and transport. The morphology and biochemical properties of actin filaments are determined by their structure and protein-protein contacts. Crowded environments can organize filaments into bundles, but less is known about how they affect F-actin structure. This study used 2D IR spectroscopy and spectral calculations to examine how crowding and bundling impact the secondary structure and local environments in filaments and weakly or strongly bundled networks. The results reveal that bundling induces changes in actin's secondary structure, leading to a decrease in β-sheet and an increase in loop conformations. Strongly bundled networks exhibit a decrease in backbone solvent exposure, with less perturbed α-helices and nearly "locked" β-sheets. Similarly, the loops become less hydrated but maintain a dynamic environment. These findings highlight the role of loop structure in actin network morphology and stability under morphology control by PEG.

The activated CD36-Src axis promotes lung adenocarcinoma cell proliferation and actin remodeling-involved metastasis in high-fat environment

Obesity/overweight and lipid metabolism disorders have become increased risk factors for lung cancer. Fatty acid translocase CD36 promotes cellular uptake of fatty acids. Whether and how CD36 facilitates lung adenocarcinoma (LUAD) growth in high-fat environment is unknown. Here, we demonstrated that palmitic acid (PA) or high-fat diet (HFD) promoted LUAD cell proliferation and metastasis in a CD36-dependent manner. Mechanistically, CD36 translocated from cytoplasm to cell membrane and interacted with Src kinase upon PA stimulation in human LUAD cells. Akt and ERK, downstream of Src, were then activated to mediate LUAD cell proliferation and metastasis. Furthermore, PA treatment promoted CD36 sarcolemmal translocation, where it activated Rac1 and upregulated MMP-9 through Src-Akt/ERK pathway, resulting in redistribution of cortactin, N-WASP and Arp2/3, and finally led to occurrence of finger-like protrusions of actin on cell surface to enhance cell metastasis. Compared with normal-chew diet (NCD) mice, the HFD group exhibited higher level of blood free fatty acid (FFA) and cholesterol (TC), developed larger xenograft LUAD tumors and enhanced tumor cell metastatic potential, which were accompanied by obvious sarcolemmal actin remodeling and were blocked by simultaneous CD36 knockdown in LUAD cells. Consistently, xenografted and tail vein-injected scramble-RNA-A549 cells but not CD36-shRNA-A549 in HFD mice formed metastatic LUAD tumors on the lung. CD36 inhibitor SSO significantly inhibited LUAD cell metastasis to the lung. Collectively, CD36 initiates Src signaling to promote LUAD cell proliferation and actin remodeling-involved metastasis under high-fat environment. Our study provides the new insights that CD36 is a valid target for LUAD therapy.

Automatic extraction of actin networks in plants

The actin cytoskeleton is essential in eukaryotes, not least in the plant kingdom where it plays key roles in cell expansion, cell division, environmental responses and pathogen defence. Yet, the precise structure-function relationships of properties of the actin network in plants are still to be unravelled, including details of how the network configuration depends upon cell type, tissue type and developmental stage. Part of the problem lies in the difficulty of extracting high-quality, quantitative measures of actin network features from microscopy data. To address this problem, we have developed DRAGoN, a novel image analysis algorithm that can automatically extract the actin network across a range of cell types, providing seventeen different quantitative measures that describe the network at a local level. Using this algorithm, we then studied a number of cases in Arabidopsis thaliana, including several different tissues, a variety of actin-affected mutants, and cells responding to powdery mildew. In many cases we found statistically-significant differences in actin network properties. In addition to these results, our algorithm is designed to be easily adaptable to other tissues, mutants and plants, and so will be a valuable asset for the study and future biological engineering of the actin cytoskeleton in globally-important crops.

Small GTPase control of pituitary hormone secretion: Evidence from studies in the goldfish (Carassius auratus) neuroendocrine model

The secretion of vertebrate pituitary hormones is regulated by multiple hypothalamic factors, which, while generally activating unique receptor systems, ultimately propagate signals through interacting intracellular regulatory elements to modulate hormone exocytosis. One important family of intracellular regulators is the monomeric small GTPases, a subset of which (Arf1/6, Rac, RhoA, and Ras) is highly conserved across vertebrates and regulates secretory vesicle exocytosis in many cell types. In this study, we investigated the roles of these small GTPases in basal and agonist-dependent hormone release from dispersed goldfish (Carassius auratus) pituitary cells in perifusion experiments. Inhibition of these small GTPases elevated basal LH and GH secretion, except for Ras inhibition which only increased basal LH release. However, variable responses were observed with regard to LH and GH responses to the two goldfish native gonadotropin-releasing hormones (GnRH2 and GnRH3). GnRH-dependent LH release, but not GH secretion, was mediated by Arf1/6 GTPases. In contrast, inhibition of Rac and RhoA GTPases selectively enhanced GnRH3- and GnRH2-dependent GH release, respectively, while Ras inhibition only enhanced GnRH3-evoked LH secretion. Together, our results reveal novel divergent cell-type- and ligand-specific roles for small GTPases in the control of goldfish pituitary hormone exocytosis in unstimulated and GnRH-evoked release.

The scaffold RhoGAP protein ARHGAP8/BPGAP1 synchronizes Rac and Rho signaling to facilitate cell migration

Rho GTPases regulate cell morphogenesis and motility under the tight control of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). However, the underlying mechanism(s) that coordinate their spatiotemporal activities, whether separately or together, remain unclear. We show that a prometastatic RhoGAP, ARHGAP8/BPGAP1, binds to inactive Rac1 and localizes to lamellipodia. BPGAP1 recruits the RacGEF Vav1 under epidermal growth factor (EGF) stimulation and activates Rac1, leading to polarized cell motility, spreading, invadopodium formation, and cell extravasation and promotes cancer cell migration. Importantly, BPGAP1 down-regulates local RhoA activity, which influences Rac1 binding to BPGAP1 and its subsequent activation by Vav1. Our results highlight the importance of BPGAP1 in recruiting Vav1 and Rac1 to promote Rac1 activation for cell motility. BPGAP1 also serves to control the timing of Rac1 activation with RhoA inactivation via its RhoGAP activity. BPGAP1, therefore, acts as a dual-function scaffold that recruits Vav1 to activate Rac1 while inactivating RhoA to synchronize both Rho and Rac signaling in cell motility. As epidermal growth factor receptor (EGFR), Vav1, RhoA, Rac1, and BPGAP1 are all associated with cancer metastasis, BPGAP1 could provide a crucial checkpoint for the EGFR-BPGAP1-Vav1-Rac1-RhoA signaling axis for cancer intervention.

Effect of the Rho-Kinase/ROCK Signaling Pathway on Cytoskeleton Components

The mechanical properties of cells are important in tissue homeostasis and enable cell growth, division, migration and the epithelial-mesenchymal transition. Mechanical properties are determined to a large extent by the cytoskeleton. The cytoskeleton is a complex and dynamic network composed of microfilaments, intermediate filaments and microtubules. These cellular structures confer both cell shape and mechanical properties. The architecture of the networks formed by the cytoskeleton is regulated by several pathways, a key one being the Rho-kinase/ROCK signaling pathway. This review describes the role of ROCK (Rho-associated coiled-coil forming kinase) and how it mediates effects on the key components of the cytoskeleton that are critical for cell behaviour.

Respiratory syncytial virus disrupts the airway epithelial barrier by decreasing cortactin and destabilizing F-actin

Respiratory syncytial virus (RSV) infection is the leading cause of acute lower respiratory tract infection in young children worldwide. Our group recently revealed that RSV infection disrupts the airway epithelial barrier in vitro and in vivo. However, the underlying molecular pathways were still elusive. Here, we report the critical roles of the filamentous actin (F-actin) network and actin-binding protein cortactin in RSV infection. We found that RSV infection causes F-actin depolymerization in 16HBE cells, and that stabilizing the F-actin network in infected cells reverses the epithelial barrier disruption. RSV infection also leads to significantly decreased cortactin in vitro and in vivo. Cortactin-knockout 16HBE cells presented barrier dysfunction, whereas overexpression of cortactin protected the epithelial barrier against RSV. The activity of Rap1 (which has Rap1A and Rap1B forms), one downstream target of cortactin, declined after RSV infection as well as in cortactin-knockout cells. Moreover, activating Rap1 attenuated RSV-induced epithelial barrier disruption. Our study proposes a key mechanism in which RSV disrupts the airway epithelial barrier via attenuating cortactin expression and destabilizing the F-actin network. The identified pathways will provide new targets for therapeutic intervention toward RSV-related disease. This article has an associated First Person interview with the first author of the paper.

The Indigenous Volatile Inhibitor 2-Methyl-2-butene Impacts Biofilm Formation and Interspecies Interaction of the Pathogenic Mucorale Rhizopus arrhizus

2-Methyl-2-butene has recently been reported to be a quorum-based volatile self-inhibitor of spore germination and growth in pathogenic Mucorale Rhizopus arrhizus. The present study aimed to elucidate if this compound can influence R. arrhizus biofilm formation and interspecies interaction. The compound was found to significantly decrease R. arrhizus biofilm formation (p < 0.001), with nearly 25% and 50% lesser biomass in the biofilms cultured with exposure to 4 and 32 µg/ml of 2-methyl-2-butene, respectively. The growth of pre-formed biofilms was also impacted, albeit to a lesser extent. Additionally, 2-methyl-2-butene was found to self-limit R. arrhizus growth during interspecies interaction with Staphylococcus aureus and was detected at a substantially greater concentration in the headspace of co-cultures (2338.75 µg/ml) compared with monocultures (69.52 µg/ml). Some of the C5 derivatives of this compound (3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-1-butyne) were also observed to partially mimic its action, such as inhibition of spore germination, but did not impact R. arrhizus biofilm formation. Finally, the treated R. arrhizus displayed changes in fungal morphology suggestive of cytoskeletal alterations, such as filopodia formation, blebs, increased longitudinal folds and/or corrugations, and finger-like and sheet-like surface protrusions, depending upon the concentration of the compound(s) and the planktonic or biofilm growth mode.

Polarization modulation with optical lock-in detection reveals universal fluorescence anisotropy of subcellular structures in live cells

The orientation of fluorophores can reveal crucial information about the structure and dynamics of their associated subcellular organelles. Despite significant progress in super-resolution, fluorescence polarization microscopy remains limited to unique samples with relatively strong polarization modulation and not applicable to the weak polarization signals in samples due to the excessive background noise. Here we apply optical lock-in detection to amplify the weak polarization modulation with super-resolution. This novel technique, termed optical lock-in detection super-resolution dipole orientation mapping (OLID-SDOM), could achieve a maximum of 100 frames per second and rapid extraction of 2D orientation, and distinguish distance up to 50 nm, making it suitable for monitoring structural dynamics concerning orientation changes in vivo. OLID-SDOM was employed to explore the universal anisotropy of a large variety of GFP-tagged subcellular organelles, including mitochondria, lysosome, Golgi, endosome, etc. We found that OUF (Orientation Uniformity Factor) of OLID-SDOM can be specific for different subcellular organelles, indicating that the anisotropy was related to the function of the organelles, and OUF can potentially be an indicator to distinguish normal and abnormal cells (even cancer cells). Furthermore, dual-color super-resolution OLID-SDOM imaging of lysosomes and actins demonstrates its potential in studying dynamic molecular interactions. The subtle anisotropy changes of expanding and shrinking dendritic spines in live neurons were observed with real-time OLID-SDOM. Revealing previously unobservable fluorescence anisotropy in various samples and indicating their underlying dynamic molecular structural changes, OLID-SDOM expands the toolkit for live cell research.

Twinfilin regulates actin assembly and Hexagonal peroxisome 1 (Hex1) localization in the pathogenesis of rice blast fungus Magnaporthe oryzae

Actin assembly at the hyphal tip is key for polar growth and pathogenesis of the rice blast fungus Magnaporthe oryzae. The mechanism of its precise assemblies and biological functions is not understood. Here, we characterized the role of M. oryzae Twinfilin (MoTwf) in M. oryzae infection through organizing the actin cables that connect to Spitzenkörper (Spk) at the hyphal tip. MoTwf could bind and bundle the actin filaments. It formed a complex with Myosin2 (MoMyo2) and the Woronin body protein Hexagonal peroxisome 1 (MoHex1). Enrichment of MoMyo2 and MoHex1 in the hyphal apical region was disrupted in a ΔMotwf loss-of-function mutant, which also showed a decrease in the number and width of actin cables. These findings indicate that MoTwf participates in the virulence of M. oryzae by organizing Spk-connected actin filaments and regulating MoHex1 distribution at the hyphal tip.

Gentamicin-induced hearing loss: A retrospective study using the Food and Drug Administration Adverse Event Reporting System and a toxicological study using drug-gene network analysis

The objectives of the study were to evaluate the relationship between gentamicin (GEN) and hearing loss using the Food and Drug Administration Adverse Event Reporting system (FAERS) database and elucidate the potential toxicological mechanism of GEN-induced hearing loss through a drug–gene network analysis.

Using the preferred terms and standardized queries from the Medical Dictionary for Regulatory Activities, we calculated the reporting odds ratios (RORs). We extracted GEN-associated genes (seed genes) and analyzed drug−gene interactions using the ClueGO plug-in in the Cytoscape software and the DIseAse MOdule Detection (DIAMOnD) algorithm.

The lower limit of the 95% confidence interval (CI) of the ROR for aminoglycosides (AG) antibacterials was over 1, and the ROR was 5.5 (5.1–6.0). We retrieved 17 seed genes related to GEN from the PharmGKB and Drug Gene Interaction databases. In total, 1018 human genes interacting with GEN were investigated using ClueGO. Through Molecular Complex Detection (MCODE) analysis, we identified 17 local gene clusters. The nodes and edges of the highest-ranked local gene cluster named “Cluster 1” were 30 and 433, respectively. According to the ClueGO analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG), Cluster 1 genes were highly enriched in “oxidative phosphorylation.” According to the ClueGO analysis using ClinVar, Cluster 1 genes were highly enriched in “mitochondrial diseases,” “mitochondrial complex I deficiency,” “hereditary hearing loss and deafness,” and “Leigh syndrome.” We identified 60 GEN-associated genes using the DIAMOnD algorithm. Several GEN-associated genes in the DIAMOnD algorithm were highly enriched in “PI3K-Akt signaling pathway,” “Ras signaling pathway,” “focal adhesion,” “MAPK signaling pathway,” “regulation of actin cytoskeleton,” “oxidative phosphorylation,” and “ECM-receptor interaction.”

Our analysis demonstrated an association between several AGs and hearing loss using the FAERS database. Drug−gene network analysis demonstrated that GEN may be associated with oxidative phosphorylation-associated genes and integrin genes, which may be associated with hearing loss.

Fascin-induced actin protrusions are suppressed by dendritic networks in giant unilamellar vesicles

The interactions between actin networks and cell membrane are immensely important for eukaryotic cell functions including cell shape changes, motility, polarity establishment, and adhesion. Actin-binding proteins are known to compete and cooperate using a finite amount of actin monomers to form distinct actin networks. How actin-bundling protein fascin and actin-branching protein Arp2/3 complex compete to remodel membranes is not entirely clear. To investigate fascin- and Arp2/3-mediated actin network remodeling, we applied a reconstitution approach encapsulating bundled and dendritic actin networks inside giant unilamellar vesicles (GUVs). Independently reconstituted, membrane-bound Arp2/3 nucleation forms an actin cortex in GUVs, whereas fascin mediates formation of actin bundles that protrude out of GUVs. Coencapsulating both fascin and Arp2/3 complex leads to polarized dendritic aggregates and significantly reduces membrane protrusions, irrespective of whether the dendritic network is membrane bound or not. However, reducing Arp2/3 complex while increasing fascin restores membrane protrusion. Such changes in network assembly and the subsequent interplay with membrane can be attributed to competition between fascin and Arp2/3 complex to utilize a finite pool of actin.

Modulation of lung cytoskeletal remodeling, RXR based metabolic cascades and inflammation to achieve redox homeostasis during extended exposures to lowered pO2

Extended exposure to low pO₂ has multiple effects on signaling cascades. Despite multiple exploratory studies, omics studies elucidating the signaling cascades essential for surviving extended low pO₂ exposures are lacking. In this study, we simulated low pO₂ (P_B = 40 kPa; 7620 m) exposure in male Sprague-Dawley rats for 3, 7 and 14 days. Redox stress assays and proteomics based network biology were performed using lungs and plasma. We observed that redox homeostasis was achieved after day 3 of exposure. We investigated the causative events for this. Proteo-bioinformatics analysis revealed STAT3 to be upstream of lung cytoskeletal processes and systemic lipid metabolism (RXR) derived inflammatory processes, which were the key events. Thus, during prolonged low pO₂ exposure, particularly those involving slowly decreasing pressures, redox homeostasis is achieved but energy metabolism is perturbed and this leads to an immune/inflammatory signaling impetus after third day of exposure. We found that an interplay of lung cytoskeletal elements, systemic energy metabolism and inflammatory proteins aid in achieving redox homeostasis and surviving extended low pO₂ exposures. Qualitative perturbations to cytoskeletal stability and innate immunity/inflammation were also observed during extended low pO₂ exposure in humans exposed to 14,000 ft for 7, 14 and 21 days.

Annexin A2 Flop-Out Mediates the Non-Vesicular Release of DAMPs/Alarmins from C6 Glioma Cells Induced by Serum-Free Conditions

Prothymosin alpha (ProTα) and S100A13 are released from C6 glioma cells under serum-free conditions via membrane tethering mediated by Ca²⁺-dependent interactions between S100A13 and p40 synaptotagmin-1 (Syt-1), which is further associated with plasma membrane syntaxin-1 (Stx-1). The present study revealed that S100A13 interacted with annexin A2 (ANXA2) and this interaction was enhanced by Ca²⁺ and p40 Syt-1. Amlexanox (Amx) inhibited the association between S100A13 and ANXA2 in C6 glioma cells cultured under serum-free conditions in the in situ proximity ligation assay. In the absence of Amx, however, the serum-free stress results in a flop-out of ANXA2 through the membrane, without the extracellular release. The intracellular delivery of anti-ANXA2 antibody blocked the serum-free stress-induced cellular loss of ProTα, S100A13, and Syt-1. The stress-induced externalization of ANXA2 was inhibited by pretreatment with siRNA for P4-ATPase, ATP8A2, under serum-free conditions, which ablates membrane lipid asymmetry. The stress-induced ProTα release via Stx-1A, ANXA2 and ATP8A2 was also evidenced by the knock-down strategy in the experiments using oxygen glucose deprivation-treated cultured neurons. These findings suggest that starvation stress-induced release of ProTα, S100A13, and p40 Syt-1 from C6 glioma cells is mediated by the ANXA2-flop-out via energy crisis-dependent recovery of membrane lipid asymmetry.

On the mechanical response of the actomyosin cortex during cell indentations

A mechanical model is presented to analyze the mechanics and dynamics of the cell cortex during indentation. We investigate the impact of active contraction on the cross-linked actin network for different probe sizes and indentation rates. The essential molecular mechanisms of filament stretching, cross-linking and motor activity, are represented by an active and viscous mechanical continuum. The filaments behave as worm-like chains linked either by passive rigid linkers or by myosin motors. In the first example, the effects of probe size and loading rate are evaluated using the model for an idealized rounded cell shape in which properties are based on the results of parallel-plate rheometry available in the literature. Extreme cases of probe size and indentation rate are taken into account. Afterward, AFM experiments were done by engaging smooth muscle cells with both sharp and spherical probes. By inverse analysis with finite element software, our simulations mimicking the experimental conditions show the model is capable of fitting the AFM data. The results provide spatiotemporal dependence on the size and rate of the mechanical stimuli. The model captures the general features of the cell response. It characterizes the actomyosin cortex as an active solid at short timescales and as a fluid at longer timescales by showing (1) higher levels of contraction in the zones of high curvature; (2) larger indentation forces as the probe size increases; and (3) increase in the apparent modulus with the indentation depth but no dependence on the rate of the mechanical stimuli. The methodology presented in this work can be used to address and predict microstructural dependence on the force generation of living cells, which can contribute to understanding the broad spectrum of results in cell experiments.

Involvement of the p38 MAPK-pHsp27 pathway in vascular hyporeactivity induced by obstructive jaundice in rats

Patients with obstructive jaundice are prone to develop cardiovascular complications during surgery. However, the underlying mechanisms remain largely unknown. The present study was aimed to investigate the role of p38 MAPK-pHsp27 pathway in vascular hyporesponsiveness induced by obstructive jaundice. Firstly, an experimental rat obstructive jaundice model was established by bile duct ligation (BDL). We found that the thoracic aorta rings isolated from BDL rats showed decreased response to norepinephrine and acetylcholine, while continuous intraperitoneal injection with SB203580, a selective P38 MAPK inhibitor, could significantly prevented BDL-induced hyporeactivity. Also, the immunohistochemistry and Western blot assays revealed that the up-regulation of pHsp27 and F-actin in thoracic aorta rings from BDL rats and bilirubin-treated vascular smooth muscle cells (VSMCs) were also inhibited by SB203580. Moreover, we identified that bilirubin could induced decreased cell proliferation of VSMCs by using CCK8 assay and which was also prevented by SB203580. All these data demonstrated that p38 MAPK-pHsp27 mediates vascular hyporesponsiveness in rats with obstructive jaundice by modulating the expression level of pHsp27 and F-actin, and that inhibition of p38 MAPK signaling could remodel the vascular activity.

Toxicity of dextran stabilized fullerene C60 against C6 Glial cells

Elevated application potential of fullerene C₆₀ paved the way to think on its adverse effect when it reaches to biological system and environment. Though fullerenes are insoluble in water, various strategies are employed to make it soluble. Method of solubilization with organic solvents, yield cytotoxic responses both in vitro and in vivo. In this study, dextran was used to stabilize C₆₀ particle. Fourier transformed-infrared spectroscopy (FT-IR) and transition electron microscopy (TEM) were used for characterization and it confirms effective surface stabilization and morphological characteristics. This was followed by various cytotoxicity studies to evaluate its bio-nano interactions. The results of the study suggest that the dextran stabilized C₆₀ nanoparticles (Dex-C₆₀) forms uniform suspension in water and was stable up to 72 h. The C6 glial cell-Dex-C₆₀ interactions indicated that the Dex-C₆₀ nanoparticles penetrate deeper into the cells and cause dose dependent toxic response. The result of the study recommended that Dex-C₆₀ nanoparticles should undergo intensive risk assessment before biomedical applications and should take proper safety measure to avoid its entry to the environment.

During Adipocyte Remodeling, Lipid Droplet Configurations Regulate Insulin Sensitivity through F-Actin and G-Actin Reorganization

Adipocytes have unique morphological traits in insulin sensitivity control. However, how the appearance of adipocytes can determine insulin sensitivity has not been understood. Here, we demonstrate that actin cytoskeleton reorganization upon lipid droplet (LD) configurations in adipocytes plays important roles in insulin-dependent glucose uptake by regulating GLUT4 trafficking. Compared to white adipocytes, brown/beige adipocytes with multilocular LDs exhibited well-developed filamentous actin (F-actin) structure and potentiated GLUT4 translocation to the plasma membrane in the presence of insulin. In contrast, LD enlargement and unilocularization in adipocytes downregulated cortical F-actin formation, eventually leading to decreased F-actin-to-globular actin (G-actin) ratio and suppression of insulin-dependent GLUT4 trafficking. Pharmacological inhibition of actin polymerization accompanied with impaired F/G-actin dynamics reduced glucose uptake in adipose tissue and conferred systemic insulin resistance in mice. Thus, our study reveals that adipocyte remodeling with different LD configurations could be an important factor to determine insulin sensitivity by modulating F/G-actin dynamics.

Cytoskeletal synchronization of CHO cells with polymer functionalized fullerene C60

Recent developments in the field of fullerene C₆₀ and its derivatives suggest its suitability in a wide range of applications ranging from photovoltaic instruments, development of solar based cells, cosmetics to enzyme inhibition treatment, and so on. These innovative applications raised possibilities of intentional or oblivious human-particle contact leading to possible deleterious effects on human health. The current study deals with the interaction of dextran functionalized fullerene C₆₀ (Dex-C₆₀) on Chinese Hamster Ovary cells. The results showed that the cell viability was not affected by Dex-C₆₀ treatment even at higher concentrations. Treatment of Dex-C₆₀ did not affect mitochondrial membrane potential and the integrity of lysosomal and cytoskeletal membrane. DNA ladder assay and nuclear staining showed that the DNA remains intact, and no fragmentation or nuclear condensation was visible. From flow cytometry analysis, the viable population of treated cells was seemed to be remaining similar to that of untreated cells. Hence, from the current result, it is concluded that Dex-C₆₀ can be a potential candidate for various biomedical applications.

Transcriptomic response is more sensitive to water deficit in shoots than roots of Vitis riparia (Michx.)

BACKGROUND

Drought is an important constraint on grapevine sustainability. Vitis riparia, widely used in rootstock and scion breeding, has been studied in isolated leaf drying response studies; however, it is essential to identify key root and shoot water deficit signaling traits in intact plants. This information will aid improved scion and rootstock selection and management practices in grapevine. RNAseq data were generated from V. riparia roots and shoots under water deficit and well-watered conditions to determine root signaling and shoot responses to water deficit.

RESULTS

Shoot elongation, photosynthetic rate, and stomatal conductance were significantly reduced in water deficit (WD) treated than in well-watered grapevines. RNAseq analysis indicated greater transcriptional differences in shoots than in roots under WD, with 6925 and 1395 genes differentially expressed, respectively (q-value < 0.05). There were 50 and 25 VitisNet pathways significantly enriched in WD relative to well-watered treatments in grapevine shoots and roots, respectively. The ABA biosynthesis genes beta-carotene hydroxylase, zeaxanthin epoxidase, and 9-cis-epoxycarotenoid dioxygenases were up-regulated in WD root and WD shoot. A positive enrichment of ABA biosynthesis genes and signaling pathways in WD grapevine roots indicated enhanced root signaling to the shoot. An increased frequency of differentially expressed reactive oxygen species scavenging (ROS) genes were found in the WD shoot. Analyses of hormone signaling genes indicated a strong ABA, auxin, and ethylene network and an ABA, cytokinin, and circadian rhythm network in both WD shoot and WD root.

CONCLUSIONS

This work supports previous findings in detached leaf studies suggesting ABA-responsive binding factor 2 (ABF2) is a central regulator in ABA signaling in the WD shoot. Likewise, ABF2 may have a key role in V. riparia WD shoot and WD root. A role for ABF3 was indicated only in WD root. WD shoot and WD root hormone expression analysis identified strong ABA, auxin, ethylene, cytokinin, and circadian rhythm signaling networks. These results present the first ABA, cytokinin, and circadian rhythm signaling network in roots under water deficit. These networks point to organ specific regulators that should be explored to further define the communication network from soil to shoot.

Identification of a basidiomycete-specific Vilse-like GTPase activating proteins (GAPs) and its roles in the production of virulence factors in Cryptococcus neoformans

Cryptococcus neoformans is a basidiomycetous pathogenic yeast that causes fatal infections in both immunocompetent and immunocompromised patients. Regulation on the production of its virulence factors is not fully understood. Here we reported the characterization of a gene, named CVH1(CNA06260), encoding a Drosophila Vilse-like RhoGAP homolog, which is hallmarked by three conserved functional domains: WW, MyTH4 and RhoGAP. Phylogenetic analysis suggests that CVH1 is highly conserved from protists to mammals and interestingly in basidiomycetes, but absent in plants or Ascomycota and other lower fungi. This phylogenetic distribution indicates an evolutionary link among these groups of organisms. Functional analyses demonstrated that CVH1 was involved in stress tolerance and virulence factor production. By disrupting CVH1, we created a second mutant cvh1Δ with the CRISPR-Cas9 editing tool. The mutant strain exhibited hypersensitivity to osmotic stress by 2 M sorbitol and NaCl, suggesting defects in the HOG signaling pathway and an interaction of Cvh1 with the HOG pathway. Hypersensitivity of cvh1Δ to 1% Congo red and 0.01% SDS suggests that the cell wall integrity was impaired in the mutant. And cvh1Δ hardly produced the pigment melanin and capsule. Our study for the first time demonstrates that the fungal Vilse-like RhoGAP CVH1 is an important regulator of multiple biological processes in C. neoformans, and provides novel insights into the regulatory circuit of stress resistance/cell wall integrity, and laccase and capsule synthesis in C. neoformans.

High Rac1 activity is functionally translated into cytosolic structures with unique nanoscale cytoskeletal architecture

Rac1 activation is at the core of signaling pathways regulating polarized cell migration. So far, it has not been possible to directly explore the structural changes triggered by Rac1 activation at the molecular level. Here, through a multiscale imaging workflow that combines biosensor imaging of Rac1 dynamics with electron cryotomography, we identified, within the crowded environment of eukaryotic cells, a unique nanoscale architecture of a flexible, signal-dependent actin structure. In cell regions with high Rac1 activity, we found a structural regime that spans from the ventral membrane up to a height of ∼60 nm above that membrane, composed of directionally unaligned, densely packed actin filaments, most shorter than 150 nm. This unique Rac1-induced morphology is markedly different from the dendritic network architecture in which relatively short filaments emanate from existing, longer actin filaments. These Rac1-mediated scaffold assemblies are devoid of large macromolecules such as ribosomes or other filament types, which are abundant at the periphery and within the remainder of the imaged volumes. Cessation of Rac1 activity induces a complete and rapid structural transition, leading to the absence of detectable remnants of such structures within 150 s, providing direct structural evidence for rapid actin filament network turnover induced by GTPase signaling events. It is tempting to speculate that this highly dynamical nanoscaffold system is sensitive to local spatial cues, thus serving to support the formation of more complex actin filament architectures-such as those mandated by epithelial-mesenchymal transition, for example-or resetting the region by completely dissipating.

Modelling and mathematical analysis of the M$_{2}$ receptor-dependent joint signalling and secondary messenger network in CHO cells

The muscarinic M$_{2}$ receptor is a prominent member of the GPCR family and strongly involved in heart diseases. Recently published experimental work explored the cellular response to iperoxo-induced M$_{2}$ receptor stimulation in Chinese hamster ovary (CHO) cells. To better understand these responses, we modelled and analysed the muscarinic M$_{2}$ receptor-dependent signalling pathway combined with relevant secondary messenger molecules using mass action. In our literature-based joint signalling and secondary messenger model, all binding and phosphorylation events are explicitly taken into account in order to enable subsequent stoichiometric matrix analysis. We propose constraint flux sampling (CFS) as a method to characterize the expected shift of the steady state reaction flux distribution due to the known amount of cAMP production and PDE4 activation. CFS correctly predicts an experimentally observable influence on the cytoskeleton structure (marked by actin and tubulin) and in consequence a change of the optical density of cells. In a second step, we use CFS to simulate the effect of knock-out experiments within our biological system, and thus to rank the influence of individual molecules on the observed change of the optical cell density. In particular, we confirm the relevance of the protein RGS14, which is supported by current literature. A combination of CFS with Elementary Flux Mode analysis enabled us to determine the possible underlying mechanism. Our analysis suggests that mathematical tools developed for metabolic network analysis can also be applied to mixed secondary messenger and signalling models. This could be very helpful to perform model checking with little effort and to generate hypotheses for further research if parameters are not known.

Iriomoteolides: novel chemical tools to study actin dynamics

Despite its promising biological profile, the cellular targets of iriomoteolide-3a, a novel 15-membered macrolide isolated from Amphidinium sp., have remained unknown. A small library of non-natural iriomoteolide-3a analogues is presented here as a result of a novel, highly convergent, catalysis-based scaffold-diversification campaign, which revealed the suitable sites for chemical editing in the original core. We provide compelling experimental evidence for actin as one of iriomoteolides' primary cellular targets, establishing the ability of these secondary metabolites to inhibit cell migration, induce severe morphological changes in cells and cause a reversible cytoplasmic retraction and reduction of F-actin fibers in a time and dose dependent manner. These results are interpreted in light of the ability of iriomoteolides to stabilize F-actin filaments. Molecular dynamics simulations provide evidence for iriomoteolide-3a binding to the barbed end of G-actin. These results showcase iriomoteolides as novel and easily tunable chemical probes for the in vitro study of actin dynamics in the context of cell motility processes including cell invasion and division.

Modulation of microenvironment for controlling the fate of periodontal ligament cells: the role of Rho/ROCK signaling and cytoskeletal dynamics

Cells behave in a variety of ways when they perceive changes in their microenvironment; the behavior of cells is guided by their coordinated interactions with growth factors, niche cells, and extracellular matrix (ECM). Modulation of the microenvironment affects the cell morphology and multiple gene expressions. Rho/Rho-associated coiled-coil-containing protein kinase (ROCK) signaling is one of the key regulators of cytoskeletal dynamics and actively and/or passively determines the cell fate, such as proliferation, migration, differentiation, and apoptosis, by reciprocal communication with the microenvironment. During periodontal wound healing, it is important to recruit the residential stem cells into the defect site for regeneration and homeostasis of the periodontal tissue. Periodontal ligament (PDL) cells contain a heterogeneous fibroblast population, including mesenchymal stem cells, and contribute to the reconstruction of tooth-supporting tissues. Therefore, bio-regeneration of PDL cells has been the ultimate goal of periodontal therapy for decades. Recent stem cell researches have shed light on intrinsic ECM properties, providing paradigm shifts in cell fate determination. This review focuses on the role of ROCK activity and the effects of Y-27632, a specific inhibitor of ROCK, in the modulation of ECM-microenvironment. Further, it presents the current understanding of how Rho/ROCK signaling affects the fate determination of stem cells, especially PDL cells. In addition, we have also discussed in detail the underlying mechanisms behind the reciprocal response to the microenvironment.

Anillin controls cleavage furrow formation in the course of asymmetric division during mouse oocyte maturation

Anillin is a scaffold protein that recruits several proteins involved in cleavage furrow formation during cytokinesis. The role of anilllin in symmetric cell divisions in somatic cells has been intensively studied, yet its involvement in cleavage furrow formation is still elusive. In this study, we investigated the role of anillin in mammalian oocyte maturation and cytokinesis. We found that anillin is localized around the nucleus during the oocyte germinal-vesicle stage, and spreads to the cytoplasm after germinal vesicle breakdown. Thereafter, anillin concentrates at the site of the cleavage furrow from anaphase I to metaphase II. Disruption of anillin activity by microinjecting oocytes with specific siRNAs resulted in a failure of polar body extrusion and asymmetric division, and caused abnormal chromosome segregation during anaphase I. Furthermore, pharmacological inhibition of myosin light chain using Y-27632 or ML-7 resulted in decreased anillin expression. Collectively, our data suggest that anillin is an essential intracellular component that maintains the integrity of asymmetric division in mouse oocytes. Mol. Reprod. Dev. 83: 792-801, 2016 © 2016 Wiley Periodicals, Inc.

Differential proteomic analysis of platelets suggested target-related proteins in rabbit platelets treated with Rhizoma Corydalis

CONTEXT

Corydalis yanhusuo W.T. Wang (Papaveraceae) (Rhizoma Corydalis) showed inhibitory effects on rabbit platelet aggregation induced by ADP, thrombin (THR) or arachidonic acid (AA).

OBJECTIVE

This study separates and identifies the possible target-related platelet proteins and suggests possible signal cascades of RC antiplatelet aggregation.

MATERIALS AND METHODS

Based on comparative proteomics, the differentially expressed platelet proteins treated before and after with 50 mg/mL RC 90% ethanol extract (for 15 min at 37 °C) were analyzed and identified by two dimensional gel electrophoresis (2-DE) and MALDI-TOF-MS/MS. To further verify the possible signalling pathways of RC antiplatelet aggregation function, the concentration of calcium (Ca²⁺) was measured by Fura-2/AM fluorescence (Ex 340/380 nm, Em 500 nm) (RC final concentrations of 0.0156-0.1563 mg/mL), the levels of P-selectin and cyclic guanosine monophosphate (cGMP) were quantified by ELISA (OD. 450 nm) (RC final concentrations of 0.0156-1.5625 mg/mL), and the 5-hydroxytryptamine (5-HT) level was measured using ortho-phthalaldehyde (OPT) fluorescence (Ex 340 nm, Em 470 nm) (RC final concentrations of 0.3125-1.5625 mg/mL).

RESULTS

The expression of 52 proteins were altered in rabbit platelets after the treatment and the MALDI-TOF-MS analysis indicated that those proteins include 12 cytoskeleton proteins, 7 cell signalling proteins, 3 molecular chaperone proteins, 6 proteins related to platelet function, 16 enzymes and 7 other related proteins. Furthermore, RC extract could decrease the levels of 5-HT [inhibition rate of 96.80% (p < 0.05, vs. THR-activated group) treated with 0.7813 mg/mL of RC], Ca²⁺[172.73 ± 5.07 to 113.56 ± 5.46 nM (p < 0.001, vs. THR-activated group) treated with 0.0313 mg/mL of RC] and P-selectin [13.48 ± 0.96 ng/3 × 10⁸ to 11.64 ± 0.17 ng/3 × 10⁸ (p < 0.05, vs. THR-activated group) treated with 0.0156 mg/mL of RC], and increase in cGMP level [38.93 ± 0.57 to 50.26 ± 4.05 ng/3 × 10⁸ (p < 0.05, vs. THR-activated group) treated with 1.5165 mg/mL of RC] in ADP (10 μmol/L), THR (0.25 u/mL) or AA-(0.205 mmol/L) activated rabbit platelets.

DISCUSSION AND CONCLUSION

The present study indicated that P2Y12 receptor might be one of the direct target proteins of RC in platelets. The signal cascades network of RC after binding with P2Y12 receptor is mediating Gαi proteins to activate downstream signalling pathways (AC and/or PI3K signalling pathways) for the inhibition of platelet aggregation.

α-Actinin-4 confers radioresistance coupled invasiveness in breast cancer cells through AKT pathway

Acquired radioresistance accompanied with increased metastatic potential is a major hurdle in effective radiotherapy of breast cancers. However, the nature of their inter-dependence and the underlying mechanism remains largely intangible. By employing radioresistant (RR) cell lines, we herein demonstrate that MCF-7 RR cells display phenotypic and molecular alterations evocative of epithelial to mesenchymal transition (EMT) with increased traction forces and membrane ruffling culminating in boosted invasiveness. We then show that these changes can be attributed to overexpression of alpha-actinin-4 (ACTN4), with ACTN4 knockdown near-completely abrogating both radioresistance and EMT-associated changes. We further found that in MCF-7 RR cells, ACTN4 mediates the observed effects by activating AKT, and downstream AKT/GSK3β signalling. Though ACTN4 plays a similar role in mediating radioresistance and invasiveness in MDA-MB-231 RR cells, co-immunoprecipitation studies reveal that these changes are effected through increased association with AKT and not by overexpression of AKT. Taken together, our study identifies ACTN4/AKT/GSK3β as a novel pathway regulating radioresistance coupled invasion which can be further explored to improve the radiotherapeutic gain.

Production of bone mineral material and BMP-2 in osteoblasts cultured on double acid-etched titanium

Background

The study of osteoblasts and their osteogenic functions is essential in order to understand them and their applications in implantology. In this sense, this study try to study BMP-2 production and bone matrix deposition, in addition to other biological variables, in osteoblasts cultured on a rough double acid-etched titanium surface (Osseotite®, Biomet 3i, Palm Beach Garden, Florida, USA) in comparison to a smooth titanium surface (machined) and a control Petri dish.

Material and Methods

An in vitro prospective study. NHOst human osteoblasts from the femur were cultured on three different surfaces: Control group: 25-mm methacrylate dish (n = 6); Machined group: titanium discs with machined surface (n = 6) and Experimental group: titanium discs with a double acid-etched nitric and hydrofluoric Osseotite® acid surface (n = 6). A quantification of the mitochondrial membrane potential, and studies of apoptosis, mobility and adhesion, bone productivity (BMP-2) and cellular bone synthesis were carried out after culturing the three groups for forty-eight hours.

Results

A statistically significant difference was observed in the production of BMP-2 between the experimental group and the other two groups (22.33% ± 11.06 vs. 13.10% ± 5.51 in the machined group and 3.88% ± 3.43 in the control group). Differences in cellular bone synthesis were also observed between the groups (28.34% ± 14.4% in the experimental group vs. 20.03% ± 6.79 in the machined group and 19.34% ± 15.93% in the control group).

Conclusions

In comparison with machined surfaces, Osseotite® surfaces favor BMP-2 production and bone synthesis as a result of the osteoblasts in contact with it.

Key words:BMP-2, Cytoskeleton, cell culture, bone matrix, apoptosis, cell viability.

Proteomic Analysis of Fetal Ovaries Reveals That Primordial Follicle Formation and Transition Are Differentially Regulated

Primordial follicle formation represents a critical phase of the initiation of embryonic reproductive organ development, while the primordial follicle transition into primary follicle determines whether oestrus or ovulation will occur in female animals. To identify molecular mechanism of new proteins which are involved in ovarian development, we employed 2D-DIGE to compare the protein expression profiles of primordial follicles and primary follicles of fetal ovaries in pigs. Fetal ovaries were collected at distinct time-points of the gestation cycle (g55 and g90). The identified proteins at the g55 time-point are mainly involved in the development of anatomical structures [reticulocalbin-1 (RCN1), reticulocalbin-3 (RCN3)], cell differentiation (actin), and stress response [heterogeneous nuclear ribonucleoprotein K (HNRNPK)]. Meanwhile, at the g90 stage, the isolated proteins with altered expression levels were mainly associated with cell proliferation [major vault protein (MVP)] and stress response [heat shock-related 70 kDa protein 2 (HSPA2)]. In conclusion, our work revealed that primordial follicle formation is regulated by RCN1, RCN3, actin, and HNRNPK, while the primordial follicle transformation to primary follicle is regulated by MVP and HSPA2. Therefore, our results provide further information for the prospective understanding of the molecular mechanism(s) involved in the regulation of the ovarian follicle development.

The guanine nucleotide exchange factor Net1 facilitates the specification of dorsal cell fates in zebrafish embryos by promoting maternal β-catenin activation

Wnt/β-catenin signaling is essential for the initiation of dorsal-ventral patterning during vertebrate embryogenesis. Maternal β-catenin accumulates in dorsal marginal nuclei during cleavage stages, but its critical target genes essential for dorsalization are silent until mid-blastula transition (MBT). Here, we find that zebrafish net1, a guanine nucleotide exchange factor, is specifically expressed in dorsal marginal blastomeres after MBT, and acts as a zygotic factor to promote the specification of dorsal cell fates. Loss- and gain-of-function experiments show that the GEF activity of Net1 is required for the activation of Wnt/β-catenin signaling in zebrafish embryos and mammalian cells. Net1 dissociates and activates PAK1 dimers, and PAK1 kinase activation causes phosphorylation of S675 of β-catenin after MBT, which ultimately leads to the transcription of downstream target genes. In summary, our results reveal that Net1-regulated β-catenin activation plays a crucial role in the dorsal axis formation during zebrafish development.

Conditional knockout of N-WASP in mouse fibroblast caused keratinocyte hyper proliferation and enhanced wound closure

Neural-Wiskott Aldrich Syndrome Protein (N-WASP) is expressed ubiquitously, regulates actin polymerization and is essential during mouse development. We have previously shown that N-WASP is critical for cell-ECM adhesion in fibroblasts. To characterize the role of N-WASP in fibroblast for skin development, we generated a conditional knockout mouse model in which fibroblast N-WASP was ablated using the Cre recombinase driven by Fibroblast Specific Protein promoter (Fsp-Cre). N-WASP^FKO (N-WASP^fl/fl; Fsp-cre) were born following Mendelian genetics, survived without any visible abnormalities for more than 1 year and were sexually reproductive, suggesting that expression of N-WASP in fibroblast is not critical for survival under laboratory conditions. Histological sections of N-WASP^FKO mice skin (13 weeks old) showed thicker epidermis with higher percentage of cells staining for proliferation marker (PCNA), suggesting that N-WASP deficient fibroblasts promote keratinocyte proliferation. N-WASP^FKO mice skin had elevated collagen content, elevated expression of FGF7 (keratinocyte growth factor) and TGFβ signaling proteins. Wound healing was faster in N-WASP^FKO mice compared to control mice and N-WASP deficient fibroblasts were found to have enhanced collagen gel contraction properties. These results suggest that N-WASP deficiency in fibroblasts improves wound healing by growth factor-mediated enhancement of keratinocyte proliferation and increased wound contraction in mice.

Filamentous actin accumulates during plant cell penetration and cell wall plug formation in Phytophthora infestans

The oomycete Phytophthora infestans is the cause of late blight in potato and tomato. It is a devastating pathogen and there is an urgent need to design alternative strategies to control the disease. To find novel potential drug targets, we used Lifeact-eGFP expressing P. infestans for high resolution live cell imaging of the actin cytoskeleton in various developmental stages. Previously, we identified actin plaques as structures that are unique for oomycetes. Here we describe two additional novel actin configurations; one associated with plug deposition in germ tubes and the other with appressoria, infection structures formed prior to host cell penetration. Plugs are composed of cell wall material that is deposited in hyphae emerging from cysts to seal off the cytoplasm-depleted base after cytoplasm retraction towards the growing tip. Preceding plug formation there was a typical local actin accumulation and during plug deposition actin remained associated with the leading edge. In appressoria, formed either on an artificial surface or upon contact with plant cells, we observed a novel aster-like actin configuration that was localized at the contact point with the surface. Our findings strongly suggest a role for the actin cytoskeleton in plug formation and plant cell penetration.

Myosins FaMyo2B and Famyo2 Affect Asexual and Sexual Development, Reduces Pathogenicity, and FaMyo2B Acts Jointly with the Myosin Passenger Protein FaSmy1 to Affect Resistance to Phenamacril in Fusarium asiaticum

We previously reported that mutations occurred in the gene myosin5 were responsible for resistance to the fungicide phenamacril in Fusarium graminearum. Here, we determined whether there is a functional link between phenamacril resistance and the myosin proteins FaMyo2B and Famyo2 in Fusarium asiaticum, which is the major causal agent of Fusarium head blight in China. We found that FaMyo2B acts jointly with FaSmy1 to affect resistance to phenamacril in F. asiaticum. We also found that FaMyo2B disruption mutant and Famyo2 deletion mutant were defective in hyphal branching, conidiation, and sexual reproduction. ΔFamyo2 also had an enhanced sensitivity to cell wall damaging agents and an abnormal distribution of septa and nuclei. In addition, the FaMyo2B and Famyo2 mutants had reduced pathogenicity on wheat coleoptiles and flowering wheat heads. Taken together, these results reveal that FaMyo2B and Famyo2 are required for several F. asiaticum developmental processes and activities, which help us better understand the resistance mechanism and find the most effective approach to control FHB.

Proteomic Analysis of Fetal Ovary Reveals That Ovarian Developmental Potential Is Greater in Meishan Pigs than in Yorkshire Pigs

Time-dependent expression of functional proteins in fetal ovaries is important to understand the developmental process of the ovary. This study was carried out to enhance our understanding of the developmental process of porcine fetal ovaries and to better address the differences in fetal ovary development of local and foreign pigs. The objective of the present study is to test the expression of key proteins that regulate the growth and development of fetal ovaries in Meishan and Yorkshire porcine breeds by using proteomics technology. Six Meishan and 6 Yorkshire pregnant gilts were used in this experiment. Fetal ovaries were obtained from Yorkshire and Meishan gilts on days 55 and 90 of the gestation period. Using 2D-DIGE (two dimensional-difference in gel electrophoresis) analysis, the results showed that there are about 1551 and 1400 proteins in gilt fetal ovaries on days 55 and 90, respectively of the gestation. Using MALDI TOF-TOF MS analysis, 27 differentially expressed proteins were identified in the fetal ovaries of the 2 breeds on day 55 of gestation, and a total of 18 proteins were identified on day 90 of gestation. These differentially expressed proteins were involved in the regulation of biological processes (cell death, stress response, cytoskeletal proteins) and molecular functions (enzyme regulator activity). We also found that alpha-1-antitrypsin, actin, vimentin, and PP2A proteins promote the formation of primordial follicles in the ovaries of Yorkshire pigs on day 55 of gestation while low expression heat shock proteins and high expression alpha-fetoproteins (AFP) may promote Meishan fetal ovarian follicular development on day 90 of gestation. These findings provide a deeper understanding of how reduced expression of heat shock proteins and increased expression of AFP can significantly reduce the risk of reproductive disease in obese Meishan sows. Our study also shows how these proteins can increase the ovulation rate and may be responsible for the low reproductive efficiency reported in other obese breeds. The ovarian developmental potential was found to be greater in Meishan pigs than in Yorkshire pigs.

Silicon-based quantum dots induce inflammation in human lung cells and disrupt extracellular matrix homeostasis

Quantum dots (QDs) are nanocrystalline semiconductor materials that have been tested for biological applications such as cancer therapy, cellular imaging and drug delivery, despite the serious lack of information of their effects on mammalian cells. The present study aimed to evaluate the potential of Si/SiO2 QDs to induce an inflammatory response in MRC-5 human lung fibroblasts. Cells were exposed to different concentrations of Si/SiO2 QDs (25-200 μg·mL(-1)) for 24, 48, 72 and 96 h. The results obtained showed that uptake of QDs was dependent on biocorona formation and the stability of nanoparticles in various biological media (minimum essential medium without or with 10% fetal bovine serum). The cell membrane damage indicated by the increase in lactate dehydrogenase release after exposure to QDs was dose- and time-dependent. The level of lysosomes increased proportionally with the concentration of QDs, whereas an accumulation of autophagosomes was also observed. Cellular morphology was affected, as shown by the disruption of actin filaments. The enhanced release of nitric oxide and the increase in interleukin-6 and interleukin-8 protein expression suggested that nanoparticles triggered an inflammatory response in MRC-5 cells. QDs decreased the protein expression and enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and also MMP-1 caseinase activity, whereas the protein levels of MMP-1 and tissue inhibitor of metalloproteinase-1 increased. The present study reveals for the first time that silicon-based QDs are able to generate inflammation in lung cells and cause an imbalance in extracellular matrix turnover through a differential regulation of MMPs and tissue inhibitor of metalloproteinase-1 protein expression.

Phenotype-dependent alteration of pathways and networks reveals a pure synergistic mechanism for compounds treating mouse cerebral ischemia

AIM

Our previous studies have showed that ursodeoxycholic acid (UA) and jasminoidin (JA) effectively reduce cerebral infarct volume in mice. In this study we explored the pure synergistic mechanism of these compounds in treatment of mouse cerebral ischemia, which was defined as synergistic actions specific for phenotype variations after excluding interference from ineffective compounds.

METHODS

Mice with focal cerebral ischemia were treated with UA, JA or a combination JA and UA (JU). Concha margaritifera (CM) was taken as ineffective compound. Cerebral infarct volume of the mice was determined, and the hippocampi were taken for microarray analysis. Particular signaling pathways and biological functions were enriched based on differentially expressed genes, and corresponding networks were constructed through Ingenuity Pathway Analysis.

RESULTS

In phenotype analysis, UA, JA, and JU significantly reduced the ischemic infarct volume with JU being superior to UA or JA alone, while CM was ineffective. As a result, 4 pathways enriched in CM were excluded. Core pathways in the phenotype-positive groups (UA or JA) were involved in neuronal homeostasis and neuropathology. JU-contributing pathways included all UA-contributing and the majority (71.7%) of JA-contributing pathways, and 10 new core pathways whose effects included inflammatory immunity, apoptosis and nervous system development. The functions of JU group included all functions of JA group, the majority (93.1%) of UA-contributing functions, and 3 new core functions, which focused on physiological system development and function.

CONCLUSION

The pure synergism between UA and JA underlies 10 new core pathways and 3 new core functions, which are involved in inflammation, immune responses, apoptosis and nervous system development.

Effects of the F-actin inhibitor latrunculin A on the budding yeast Saccharomyces cerevisiae

Our basic cell biology research was aimed at investigating the effect on eukaryotic cells of the sudden loss of the F-actin cytoskeleton. Cells treated with latrunculin A (LA) in yeast extract peptone dextrose (YEPD) medium were examined using phase-contrast and fluorescent microscopy, freeze-substitution, transmission and scanning electron microscopy, counted using a Bürker chamber and their absorbance measured. The cells responded to the presence of LA, an F-actin inhibitor, with the disappearance of actin patches, actin cables and actin rings. This resulted in the formation of larger spherical cells with irregular morphology in the cell walls and ultrastructural disorder of the cell organelles and secretory vesicles. Instead of buds, LA-inhibited cells formed only 'table-mountain-like' wide flattened swellings without apical growth with a thinner glucan cell-wall layer containing β-1,3-glucan microfibrils. The LA-inhibited cells lysed. Actin cables and patches were required for bud formation and bud growth. In addition, actin patches were required for the formation of β-1,3-glucan microfibrils in the bud cell wall. LA has fungistatic, fungicidal and fungilytic effects on the budding yeast Saccharomyces cerevisiae.

The Theory of Ultra-Coarse-Graining. 2. Numerical Implementation

The increasing interest in the modeling of complex macromolecular systems in recent years has spurred the development of numerous coarse-graining (CG) techniques. However, many of the CG models are constructed assuming that all details beneath the resolution of CG degrees of freedom are fast and average out, which sets limits on the resolution of feasible coarse-grainings and on the range of applications of the CG models. Ultra-coarse-graining (UCG) makes it possible to construct models at any desired resolution while accounting for discrete conformational or chemical changes within the CG sites that can modulate the interactions between them. Here, we discuss the UCG methodology and its numerical implementation. We pay particular attention to the numerical mechanism for including state transitions between different conformations within CG sites because this has not been discussed previously. Using a simple example of 1,2-dichloroethane, we demonstrate the ability of the UCG model to reproduce the multiconfigurational behavior of this molecular liquid, even when each molecule is modeled with only one CG site. The methodology can also be applied to other molecular liquids and macromolecular systems with time scale separation between conformational transitions and other intramolecular motions and rotations.

Effects of cadmium exposure on the gill proteome of Cottus gobio: modulatory effects of prior thermal acclimation

Temperature and trace metals are common environmental stressors, and their importance is increasing due to global climate change and anthropogenic pollution. The aim of the present study was to investigate whether acclimation to elevated temperature affects the response of the European bullhead (Cottus gobio) to subsequent cadmium (Cd) exposure by using enzymatic and proteomic approaches. Fish acclimated to 15 (standard temperature), 18 or 21 °C for 28 days were exposed to 1mg Cd/L for 4 days at the respective acclimation temperature. First, exposure to Cd significantly decreased the activity of the lactate dehydrogenase (LDH) in gills of fish acclimated to 15 or 18 °C. However, an acclimation to 21 °C suppressed the inhibitory effect of Cd. Second, using a proteomic analysis by 2D-DIGE, we observed that thermal acclimation was the first parameter affecting the protein expression profile in gills of C. gobio, while subsequent Cd exposure seemed to attenuate this temperature effect. Moreover, our results showed opposite effects of these two environmental stressors at protein expression level. From the 52 protein spots displaying significant interaction effects of temperature and Cd exposure, a total of 28 different proteins were identified using nano LC-MS/MS and the Peptide and Protein Prophet algorithms of Scaffold software. The identified differentially expressed proteins can be categorized into diverse functional classes, related to protein turnover, folding and chaperoning, metabolic process, ion transport, cell signaling and cytoskeleton. Within a same functional class, we further reported that several proteins displayed reverse responses following sequential exposure to heat and Cd. This work provides insights into the molecular pathways potentially involved in heat acclimation process and the interactive effects of temperature and Cd stress in ectothermic vertebrates.