Targets of fibroblast growth factor 1 (FGF-1) and FGF-2 signaling involved in the invasive and tumorigenic behavior of carcinoma cells

Fibroblast growth factor (FGF)-1 and -2 have potent biological activities implicated in malignant tumor development. Their autocrine and nonautocrine activity in tumor progression of carcinoma was investigated in the NBT-II cell system. Cells were manipulated to either produce and be autocrine for FGF-1 or -2 or to only produce but not respond to these factors. The autocrine cells are highly invasive and tumorigenic and the determination of specific targets of FGF/fibroblast growth factor receptor (FGFR) signaling was assessed. In vitro studies showed that nonautocrine cells behave like epithelial parental cells, whereas autocrine cells have a mesenchymal phenotype correlated with the overexpression of urokinase plasminogen activator receptor (uPAR), the internalization of E-cadherin, and the redistribution of beta-catenin from the cell surface to the cytoplasm and nucleus. uPAR was defined as an early target, whereas E-cadherin and the leukocyte common antigen-related protein-tyrosine phosphatase (LAR-PTP) were later targets of FGF signaling, with FGFR1 activation more efficient than FGFR2 at modulating these targets. Behavior of autocrine cells was consistent with a decrease of tumor-suppressive activities of both E-cadherin and LAR-PTP. These molecular analyses show that the potential of these two growth factors in tumor progression is highly dependent on specific FGFR signaling and highlights its importance as a target for antitumor therapy.     

Essential metals,vitamins and antioxidant enzyme activities in COVID-19 patients and their potential associations with the disease severity

BioMetals - The role of micronutrient deficiency in the pathogenesis of COVID-19 has been reviewed in the literature; however, the data are limited and conflicting. This study investigated the...     

Overexpressed recombinant quorum quenching lactonase reduces the virulence,motility and biofilm formation of multidrug-resistant Pseudomonas aeruginosa clinical isolates

The increasing occurrence of resistance among Pseudomonas aeruginosa clinical isolates necessitates finding alternatives to antibiotics for controlling the infection of such pathogenic bacteria. In this study, lactonase gene ahl-1 from Bacillus weihenstephanensis isolate-P65 was successfully cloned and expressed in Escherichia coli BL21 (DE3) under the control of T7 promoter for utilizing its quorum quenching activity against three multidrug-resistant (MDR) P. aeruginosa clinical isolates. The biological activity of the overexpressed lactonase enzyme (Ahl-1), tested using a synthetic signal and Chromobacterium violaceum CV026 as a biosensor, displayed good catalytic activity using hexanoyl homoserine lactone (HHL) as a substrate and Chromobacterium violaceum (CV026) as a biosensor (77.2 and 133 nm min⁻¹ for the crude and the purified Ahl-lactonase enzymes, respectively). Upon challenging its ability to inhibit the virulence of three MDR P. aeruginosa clinical isolates, recombinant Ahl-1 successfully prevented the accumulation of acylhomoserine lactone signals resulting in a significant reduction in the investigated virulence determinants; protease (from 40 up to 75.5%), pyocyanin (48–75.9%), and rhamnolipids (52.7–63.4%) (P value < 0.05). Ahl-1 also displayed significant inhibitory activities on the swarming motility and biofilm formation of the three tested MDR P. aeruginosa clinical isolates (P value < 0.05). Consequently, Ahl-1 lactonase enzyme in this study is considered a promising therapeutic agent to inhibit P. aeruginosa pathogenicity with no fear of emergence of resistance.

     

Mercury (Hg) Exposure in Breast-Fed Infants and Their Mothers and the Evidence of Oxidative Stress

The objective of this work was to assess exposure to mercury (Hg) and its induction of oxidative stress in 155 healthy lactating Saudi mothers and their infants. Samples of breast milk and blood were collected from the mothers, while urine was taken from both infants and mothers. Both urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) were measured in mothers and infants as biomarkers of oxidative stress. The mean concentration of Hg in breast milk was 1.19 μg/L (range 0.012–6.44 μg/L) with only one mother having Hg >4 μg/L, the upper limit established by the US Agency for Toxic Substance and Disease Registry. However, 57.4 % had Hg ≥1 μg/L, the background level for Hg in human milk. The mean urinary Hg corrected for creatinine (Hg-C) in mothers and infants was 1.47 and 7.90 μg/g creatinine, respectively, with a significant correlation between the two (p?<?0.001). Urinary Hg levels over 5 μg/g creatinine (the background level in an unexposed population) were found in 3.3 % of mothers and 50.1 % of infants. None of the mothers had total blood Hg above the US Environmental Protection Agency’s maximum reference dose of 5.8 μg/L. No correlation was noted between urinary Hg in infants and Hg in breast milk (p?>?0.05). Hg in breast milk, though, was associated with Hg in blood (p?<?0.001), suggesting the efficient transfer of Hg from blood to milk. Hg in the breast milk of mothers and in the urine of infants affected the excretion of urinary MDA and 8-OHdG, respectively, in a dose-related manner. These findings reveal for the first time lactational exposure to Hg-induced oxidative stress in breast-fed infants, which may play a role in pathogenesis, particularly during neurodevelopment. This will also contribute to the debate over the benefits of breast milk versus the adverse effects of exposure to pollutants. Nevertheless, breastfeeding should not be discouraged, but efforts should be made to identify and eliminate the source of Hg exposure in the population.     

Weight and metabolic effects of CPAP in obstructive sleep apnea patients with obesity

Background

Obstructive sleep apnea (OSA) is associated with obesity, insulin resistance (IR) and diabetes. Continuous positive airway pressure (CPAP) rapidly mitigates OSA in obese subjects but its metabolic effects are not well-characterized. We postulated that CPAP will decrease IR, ghrelin and resistin and increase adiponectin levels in this setting.

Methods

In a pre- and post-treatment, within-subject design, insulin and appetite-regulating hormones were assayed in 20 obese subjects with OSA before and after 6 months of CPAP use. Primary outcome measures included glucose, insulin, and IR levels. Other measures included ghrelin, leptin, adiponectin and resistin levels. Body weight change were recorded and used to examine the relationship between glucose regulation and appetite-regulating hormones.

Results

CPAP effectively improved hypoxia. However, subjects had increased insulin and IR. Fasting ghrelin decreased significantly while leptin, adiponectin and resistin remained unchanged. Forty percent of patients gained weight significantly. Changes in body weight directly correlated with changes in insulin and IR. Ghrelin changes inversely correlated with changes in IR but did not change as a function of weight.

Conclusions

Weight change rather than elimination of hypoxia modulated alterations in IR in obese patients with OSA during the first six months of CPAP therapy.     

Conserved biophysical features of the CaV2 presynaptic Ca2+ channel homologue from the early-diverging animal Trichoplax adhaerens

The dominant role of Ca_V2 voltage-gated calcium channels for driving neurotransmitter release is broadly conserved. Given the overlapping functional properties of Ca_V2 and Ca_V1 channels, and less so Ca_V3 channels, it is unclear why there have not been major shifts toward dependence on other Ca_V channels for synaptic transmission. Here, we provide a structural and functional profile of the Ca_V2 channel cloned from the early-diverging animal Trichoplax adhaerens, which lacks a nervous system but possesses single gene homologues for Ca_V1–Ca_V3 channels. Remarkably, the highly divergent channel possesses similar features as human Ca_V2.1 and other Ca_V2 channels, including high voltage–activated currents that are larger in external Ba²⁺ than in Ca²⁺; voltage-dependent kinetics of activation, inactivation, and deactivation; and bimodal recovery from inactivation. Altogether, the functional profile of Trichoplax Ca_V2 suggests that the core features of presynaptic Ca_V2 channels were established early during animal evolution, after Ca_V1 and Ca_V2 channels emerged via proposed gene duplication from an ancestral Ca_V1/2 type channel. The Trichoplax channel was relatively insensitive to mammalian Ca_V2 channel blockers ω-agatoxin-IVA and ω-conotoxin-GVIA and to metal cation blockers Cd²⁺ and Ni²⁺. Also absent was the capacity for voltage-dependent G-protein inhibition by co-expressed Trichoplax Gβγ subunits, which nevertheless inhibited the human Ca_V2.1 channel, suggesting that this modulatory capacity evolved via changes in channel sequence/structure, and not G proteins. Last, the Trichoplax channel was immunolocalized in cells that express an endomorphin-like peptide implicated in cell signaling and locomotive behavior and other likely secretory cells, suggesting contributions to regulated exocytosis.     

Structural basis for ARF1-mediated recruitment of ARHGAP21 to Golgi membranes

ARHGAP21 is a Rho family GTPase-activating protein (RhoGAP) that controls the Arp2/3 complex and F-actin dynamics at the Golgi complex by regulating the activity of the small GTPase Cdc42. ARHGAP21 is recruited to the Golgi by binding to another small GTPase, ARF1. Here, we present the crystal structure of the activated GTP-bound form of ARF1 in a complex with the Arf-binding domain (ArfBD) of ARHGAP21 at 2.1 A resolution. We show that ArfBD comprises a PH domain adjoining a C-terminal alpha helix, and that ARF1 interacts with both of these structural motifs through its switch regions and triggers structural rearrangement of the PH domain. We used site-directed mutagenesis to confirm that both the PH domain and the helical motif are essential for the binding of ArfBD to ARF1 and for its recruitment to the Golgi. Our data demonstrate that two well-known small GTPase-binding motifs, the PH domain and the alpha helical motif, can combine to create a novel mode of binding to Arfs.     

Reducing Copper Availability in Contaminated Soils Using Drinking Water Treatment Residuals

Copper mobility and availability in soil environments is largely controlled by Cu sorption reactions as well as its chemical forms. In this study, equilibrium, kinetic batch experiments, and a chemical fractionation scheme were carried out to evaluate effects of drinking water treatment residual (DWTR) application on sorption and bioavailability of Cu in three arid zone soils having different properties. Distinct differences in the amounts of Cu sorbed among the different soils were observed where highest sorption was associated with clay, OM, and CEC contents. The quantity of Cu sorbed on the three studied soils drastically increased as a result of increasing rates of DWTR application from 2% to 12% (w/w). Freundlich distribution coefficient (K_f) values indicate that Cu sorption affinities for the studied soils followed the trend Typic torrifluvent (TF) > Typic calciorthids (CO) > Typic torripsamment (TP) soils. The sorption of Cu was initially fast with 95, 92, and 73% of Cu sorbed on TF and CO and TP unamended soils, respectively, in the first 60 min. Following the initial fast reaction, the sorption reaction continued for 63 h, after which only a small amount of additional sorption occurred (2–6%). The parabolic diffusion law and the power function models described Cu sorption kinetics in all the sorbents studied equally well as the R² values were quite high and SE values were low. Addition of DWTR drastically reduced non-residual (NORS) Cu and simultaneously increased residual (RS) Cu fractions. At 12% application rate, DWTR decreased NORS-Cu in nonamended soils from 10.9 to 4.2, from 50.2 to 21.5, and from 78.6 to 33.3% in TF, CO, and TP soils, respectively. Our results suggest that as the application rate of DWTR to Cu-contaminated soils increased, more Cu was associated with the residual fractions, which decreased potential Cu mobility and bioavailability in these soils.