Investigation of the effect of homocysteinylation of substance P on its binding to the NK1 receptor using molecular dynamics simulation

Substance P is a neurotransmitter or modulator in both the central and peripheral nervous systems. In this work, modifications of the lysine in SP by homocysteine and an acetyl group as well as the conformational dynamics of the native and modified SP peptides and their complexes with the NK1 receptor were studied via MD simulation. It was found that modifying SP stabilizes the peptide structure, but the modified SP peptides are less likely to bind to the NK1 receptor, so the resulting complexes are less stable. The RMSD of native SP (~0.33 nm) is about twice as large as that of the modified SP peptides (~0.18 nm), while the RMSD for the receptor complexed with native SP is ~0.3 nm, and that for the receptor complexed with either of the modified peptides is ~0.35 nm, which demonstrates the high stability of the modified SP peptides as well as the receptor complexed with native SP. Such behavior was also observed in other structural analyses. The binding free energies of the native and modified SP peptides with the NK1 receptor were also compared. The ΔG_bind values for the binding of homocysteinylated SP to the NK1 receptor and the binding of the acetylated SP and native SP to the NK1 receptor were ?38.89, ?64.46, and???264.52 kJ mol^?1, respectively. Modification of the lysine of SP decreases the binding affinity of the peptide to the NK1 receptor. In other words, homocysteinylation or acetylation of SP leads to weaker interactions of the peptide with the NK1 receptor compared to those between native SP and NK1. We propose that this phenomenon leads to increased levels of homocysteinylated SP in plasma in many diseases such as breast cancer.

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Graphical abstract Substance P (SP) is a neuropeptide which binds to the NK1 receptor. SP is of great pharmacological interest, as agonists and antagonists of SP can potentially be used to treat many chronic diseases. Therefore, in this work, the lysine (LYS) in SP was theoretically modified with a homocysteine or acetyl group to explore the effects of such a modification on the binding affinity of this peptide with the NK1 receptor and the structural dynamics of the resulting complex

     

Use of bacterial acc deaminase to increase oil (especially poly aromatic hydrocarbons) phytoremediation efficiency for maize (zea mays) seedlings

Oil presence in soil, as a stressor, reduces phytoremediation efficiency through an increase in the plant stress ethylene. Bacterial 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, as a plant stress ethylene reducer, was employed to increase oil phytoremediation efficiency. For this purpose, the ability of ACC deaminase-producing Pseudomonas strains to grow in oil-polluted culture media and withstand various concentrations of oil and also their ability to reduce plant stress ethylene and enhance some growth characteristics of maize and finally their effects on increasing phytoremediation efficiency of poly aromatic hydrocarbons (PAHs) in soil were investigated. Based on the results, of tested strains just P9 and P12 were able to perform oil degradation. Increasing oil concentration from 0 to 10% augmented these two strains population, 15.7% and 12.9%, respectively. The maximum increase in maize growth was observed in presence of P12 strain. Results of high-performance liquid chromatography (HPLC) revealed that PAHs phytoremediation efficiency was higher for inoculated seeds than uninoculated. The highest plant growth and PAHs removal percentage (74.9%) from oil-polluted soil was observed in maize inoculated with P12. These results indicate the significance of ACC deaminase producing bacteria in alleviation of plant stress ethylene in oil-polluted soils and increasing phytoremediation efficiency of such soils.     

Innovative therapies for prostate cancer treatment

Androgen ablation is effective therapy for metastatic prostate cancer, but the majority of men eventually become refractory to this intervention. Cytotoxic chemotherapy offers palliation to symptomatic patients with hormone-refractory prostate cancer (HRPC); however, no chemotherapy regimen has yet been shown to prolong survival. There is a clear need for new agents and drug targets for the treatment of HRPC. A number of innovative therapeutic approaches that are rationally based and target driven are under investigation. This article reviews the development of antisense oligonucleotides that inhibit the anti-apoptotic bcL-2 protein. Approaches that target the epidermal growth factor receptor, the platelet derived growth factor receptor, and nuclear factor kappa-B are also discussed. There is much expectation that these therapies alone or in combination with cytotoxic chemotherapy will impact the clinical outcome of patients with HRPC.     

Evaluation of citrate synthase activity in brain of rats submitted to an animal model of mania induced by ouabain

Bipolar disorder (BD) is a psychiatric disorder characterized by alternating episodes of mania and depression. The intracerebroventricular (i.c.v) administration of ouabain (a Na⁺/K⁺-ATPase inhibitor) in rats has been used as an animal model of mania, because present face, construct and predictive validities. Several studies strongly suggest that mitochondrial dysfunction play a central role in the pathophysiology of BD. Citrate synthase (CS) is an enzyme localized in the mitochondrial matrix and represents one of the most important steps of Krebs cycle. The aim of this study was to investigate CS activity in brain of rats after the administration of ouabain. Adult male Wistar rats received a single i.c.v. administration of ouabain (10^?2 and 10^?3 M) or vehicle (control group). Locomotor activity was measured using the open field task. CS activity was measured in the brain of rats immediately (1 h) and 7 days after ouabain administration. Our results showed that spontaneous locomotion was increased 1 h after ouabain administration, and that the hyperlocomotion persists 7 days after the administration. Moreover, CS activity was inhibited immediately after the administration of ouabain in the prefrontal cortex at the doses of 10^?3 and 10^?2 M. This inhibition remains by 7 days after the administration of ouabain. On the other hand, it was not observed any difference in CS activity in the hippocampus and striatum. Considering that inhibition of CS activity may reflect a mitochondrial dysfunction, it is tempting to speculate that the reduction of brain energy metabolism might be related to the pathophysiology of BD.     

Cavin4 interacts with Bin1 to promote T-tubule formation and stability in developing skeletal muscle

The cavin proteins are essential for caveola biogenesis and function. Here, we identify a role for the muscle-specific component, Cavin4, in skeletal muscle T-tubule development by analyzing two vertebrate systems, mouse and zebrafish. In both models, Cavin4 localized to T-tubules, and loss of Cavin4 resulted in aberrant T-tubule maturation. In zebrafish, which possess duplicated cavin4 paralogs, Cavin4b was shown to directly interact with the T-tubule–associated BAR domain protein Bin1. Loss of both Cavin4a and Cavin4b caused aberrant accumulation of interconnected caveolae within the T-tubules, a fragmented T-tubule network enriched in Caveolin-3, and an impaired Ca²⁺ response upon mechanical stimulation. We propose a role for Cavin4 in remodeling the T-tubule membrane early in development by recycling caveolar components from the T-tubule to the sarcolemma. This generates a stable T-tubule domain lacking caveolae that is essential for T-tubule function.     

The Time Distribution of Sulfadoxine-Pyrimethamine Protection from Malaria

Sulfadoxine-pyrimethamine (SP) has been one of the most widely used antimalarial treatments world-wide, and is also used prophylactically in vulnerable populations. In this paper, we develop a mathematical model which allows us to infer the time distribution of SP protection from drug-trial data. Fitting our model to data from a controlled field study in Mali, we find that SP provided protection from malaria for an average of 37.9?days in this pediatric population. We demonstrate that the duration of SP protection is not well described by an exponential distribution, and in fact has a much narrower dispersal about the mean; the best-fit standard deviation predicted by our model was only 17.0?days, as opposed to 41.8?days for the exponential model. We estimate the monthly entomological inoculation rate and the basic reproductive number for malaria in this population, and demonstrate that extremely high SP treatment rates would be necessary to maintain an effective reproductive number below one throughout a single rainy season. These results have implications for further efforts to model the impact of SP treatment, or for investigations of the optimal timing of prophylactic SP.     

B cell-specific expression of B7-2 is required for follicular Th cell function in response to vaccinia virus

Follicular Th (T(FH)) cells are specialized in provision of help to B cells that is essential for promoting protective Ab responses. CD28/B7 (B7-1 and B7-2) interactions are required for germinal center (GC) formation, but it is not clear if they simply support activation of naive CD4 T cells during initiation of responses by dendritic cells or if they directly control T(FH) cells and/or directly influence follicular B cell differentiation. Using a model of vaccinia virus infection, we show that B7-2 but not B7-1 deficiency profoundly impaired T(FH) cell development but did not affect CD4 T cell priming and Th1 differentiation. Consistent with this, B7-2 but not B7-1 was required for acquisition of GC B cell phenotype, plasma cell generation, and virus-specific neutralizing Ab responses. Mixed adoptive transfer experiments indicated that bidirectional interactions between CD28 expressed on activated T cells and B7-2 expressed on follicular B cells were essential for maintenance of the T(FH) phenotype and GC B cell development. Our data provide new insight into the source and nature of molecules required for T(FH) cells to direct GC B cell responses.