Insights into Domain Organization and Regulatory Mechanism of Cystathionine Beta-Synthase from Toxoplasma gondii

Cystathionine beta-synthase (CBS) is a key regulator of homocysteine metabolism. Although eukaryotic CBS have a similar domain architecture with a catalytic core and a C-terminal Bateman module, their regulation varies widely across phyla. In human CBS (HsCBS), the C-terminus has an autoinhibitory effect by acting as a cap that avoids the entry of substrates into the catalytic site. The binding of the allosteric modulator AdoMet to this region alleviates this cap, allowing the protein to progress from a basal toward an activated state. The same activation is obtained by artificial removal or heat-denaturation of the Bateman module. Recently, we reported the crystal structure of CBS from Toxoplasma gondii (TgCBS) showing that the enzyme assembles into basket-like dimers similar to the basal conformers of HsCBS. These findings would suggest a similar lid function for the Bateman module which, as in HsCBS, should relax in the absence of the C-terminal module. However, herein we demonstrate that, in contrast with HsCBS, removal of the Bateman module in TgCBS through deletion mutagenesis, limited proteolysis, or thermal denaturation has no effects on its activity, oligomerization, and thermal stability. This opposite behavior we have now found in TgCBS provides evidence of a novel type of CBS regulation.     

Hypothalamic NPY-Y1R Interacts with Gonadal Hormones in Protecting Female Mice against Obesity and Neuroinflammation

We previously demonstrated that Npy1r^rfb mice, which carry the conditional inactivation of the Npy1r gene in forebrain principal neurons, display a sexually dimorphic phenotype, with male mice showing metabolic, hormonal and behavioral effects and females being only marginally affected. Moreover, exposure of Npy1r^rfb male mice to a high-fat diet (HFD) increased body weight growth, adipose tissue, blood glucose levels and caloric intake compared to Npy1r^2lox male controls. We used conditional knockout Npy1r^rfb and Npy1r^2lox control mice to examine whether forebrain disruption of the Npy1r gene affects susceptibility to obesity and associated disorders of cycling and ovariectomized (ovx) female mice in a standard diet (SD) regimen or exposed to an HFD for 3 months. The conditional deletion of the Npy1r gene increased body weight and subcutaneous white adipose tissue weight in both SD- and HFD-fed ovx females but not in cycling females. Moreover, compared with ovx control females on the same diet regimen, Npy1r^rfb females displayed increased microglia number and activation, increased expression of Neuropeptide Y (NPY)-immunoreactivity (IR) and decreased expression of proopiomelanocortin-IR in the hypothalamic arcuate nucleus (ARC). These results suggest that in the ARC NPY-Y1R reduces the susceptibility to obesity of female mice with low levels of gonadal hormones and that this effect may be mediated via NPY-Y1R ability to protect the brain against neuroinflammation.     

Synergistic Effects of A Combined Treatment of Glioblastoma U251 Cells with An Anti-miR-10b-5p Molecule and An AntiCancer Agent Based on 1-(3′,4′,5′-Trimethoxyphenyl)-2-Aryl-1H-Imidazole Scaffold

(1) Background: In the development of new and more effective anticancer approaches, combined treatments appear of great interest. Combination therapy could be of importance in the management of glioblastoma (GBM), a lethal malignancy that accounts for 42% of cancer of the central nervous system, with a median survival of 15 months. This study aimed to verify the activity on a glioblastoma cancer cell line of one of the most active compounds of a novel series of tubulin polymerization inhibitors based on the 1-(3′,4′,5′-trimethoxyphenyl)-2-aryl-1H-imidazole scaffold, used in combination with a miRNA inhibitor molecule targeting the oncomiRNA miR-10b-5p. This microRNA was selected in consideration of the role of miR-10b-5p on the onset and progression of glioblastoma. (2) Methods: Apoptosis was analyzed by Annexin-V and Caspase 3/7 assays, efficacy of the anti-miR-10b-5p was assessed by determining the miR-10b-5p content by RT-qPCR. (3) Results: The results obtained show that a “combination therapy” performed by combining the use of an anti-miR-10b-5p and a 1-(3′,4′,5′-trimethoxyphenyl)-2-aryl-1H-imidazole derivative is an encouraging strategy to boost the efficacy of anticancer therapies and at the same time to reduce side effects.     

Secreted miR-153 Controls Proliferation and Invasion of Higher Gleason Score Prostate Cancer

Prostate cancer (PC) is a male common neoplasm and is the second leading cause of cancer death in American men. PC is traditionally diagnosed by the evaluation of prostate secreted antigen (PSA) in the blood. Due to the high levels of false positives, digital rectal examination and transrectal ultrasound guided biopsy are necessary in uncertain cases with elevated PSA levels. Nevertheless, the high mortality rate suggests that new PC biomarkers are urgently needed to help clinical diagnosis. In a previous study, we have identified a network of genes, altered in high Gleason Score (GS) PC (GS ≥ 7), being regulated by miR-153. Until now, no publication has explained the mechanism of action of miR-153 in PC. By in vitro studies, we found that the overexpression of miR-153 in high GS cell lines is required to control cell proliferation, migration and invasion rates, targeting Kruppel-like factor 5 (KLF5). Moreover, miR-153 could be secreted by exosomes and microvesicles in the microenvironment and, once entered into the surrounding tissue, could influence cellular growth. Being upregulated in high GS human PC, miR-153 could be proposed as a circulating biomarker for PC diagnosis.     

Synthesis,In Vitro and In Silico Analysis of New Oleanolic Acid and Lupeol Derivatives against Leukemia Cell Lines: Involvement of the NF-κB Pathway

Oleanolic acid (OA) and Lupeol (LU) belong to the class of natural triterpenes and are endowed with a wide range of biological activities, including cytotoxicity toward several cancer cell lines. In this context, we investigated a set of compounds obtained from the two natural precursors for the cytotoxicity against leukemia HL60 cells and the multidrug-resistant (MDR) variant HL60R. Six new semi-synthetic triterpenes have been synthetized, fully characterized, and were investigated together with other triterpenes compounds for their pharmacological mechanism of action. The interaction of the more cytotoxic compounds with the nuclear factor kappa B (NF-κB) pathway has been also evaluated with the aid of docking. The lupane-like compounds were more active than the precursor, while the oleane-like compounds showed more complex behavior. Both OA and LU derivatives possess a similar interaction pattern with the p65 subunit of NF-κB, justifying the similar trend in their ability to inhibit the binding of p65 to DNA. Further, some of the derivatives tested were able to increase IκB-α levels preventing the translocation of NF-κB to the nucleus. In conclusion, this study offers a deeper insight on the pharmacological action of triterpenes toward leukemia cells, and it improves the background useful for the development of new anti-cancer drugs.     

Stabilizing conditions for model predictive control

Existing stabilizing conditions that use a terminal cost and constraint that, if satisfied, ensure stability and recursive feasibility for deterministic, robust, and stochastic model predictive control are briefly reviewed and analyzed. It is pointed out that these conditions do not cover all situations. Proposals are made to cover a wider range of desired applications.     

Reviewing the effects of vacuum frying on frying medium and fried foods properties

Vacuum frying (VF) is a process developed at a pressure lower than atmospheric pressure, in which lower temperatures are employed to remove moisture from the food and reduce the oil content in the final product. Diverse studies have been published for VF or assisted with microwave and ultrasound, facing the challenges of accomplishing the physical and sensory properties appreciated in fried products. The studied matrices under VF include mainly vegetable origin foods (apple, banana, carrot, donuts, kiwi, mushroom, pea, pear, potato and sweet potato) and some animal origin products (chicken nuggets, fish fillets and surimi products). This review aimed to show recent and relevant findings of the application of VF, analysing both the effects on the frying medium and the impact on the fried foods. The inclusion of microwave and ultrasound technologies aids in the obtention of high-quality products in terms of sensory and textural attributes, oil content as well as reduced oil degradation. This technique may provide safer and stable fried foods with lower oil content aiding in improving the diet of consumers and reducing production costs.     

The CIO stereotype: Content,bias, and impact

The current work examines whether there is a stereotype of CIOs that can influence decisions about their role in organizations. We find evidence for a CIO stereotype informed by both an IT stereotype and a general leader stereotype, although CIOs are perceived to have more in common with IT personnel than leaders. Two experiments showed that the CIO stereotype was capable of biasing perceptions of CIOs’ suitability to occupy strategic roles (i.e., a “glass ceiling” effect) and the extent to which they are blamed for negative outcomes (i.e., a “glass cliff” effect). These findings point to the challenges CIOs face in gaining and maintaining strategic leadership roles in organizations.     

Mycobacterial and Human Ferrous Nitrobindins: Spectroscopic and Reactivity Properties

Structural and functional properties of ferrous Mycobacterium tuberculosis (Mt-Nb) and human (Hs-Nb) nitrobindins (Nbs) were investigated. At pH 7.0 and 25.0 °C, the unliganded Fe(II) species is penta-coordinated and unlike most other hemoproteins no pH-dependence of its coordination was detected over the pH range between 2.2 and 7.0. Further, despite a very open distal side of the heme pocket (as also indicated by the vanishingly small geminate recombination of CO for both Nbs), which exposes the heme pocket to the bulk solvent, their reactivity toward ligands, such as CO and NO, is significantly slower than in most hemoproteins, envisaging either a proximal barrier for ligand binding and/or crowding of H₂O molecules in the distal side of the heme pocket which impairs ligand binding to the heme Fe-atom. On the other hand, liganded species display already at pH 7.0 and 25 °C a severe weakening (in the case of CO) and a cleavage (in the case of NO) of the proximal Fe-His bond, suggesting that the ligand-linked movement of the Fe(II) atom onto the heme plane brings about a marked lengthening of the proximal Fe-imidazole bond, eventually leading to its rupture. This structural evidence is accompanied by a marked enhancement of both ligands dissociation rate constants. As a whole, these data clearly indicate that structural–functional relationships in Nbs strongly differ from what observed in mammalian and truncated hemoproteins, suggesting that Nbs play a functional role clearly distinct from other eukaryotic and prokaryotic hemoproteins.     

Ablation of Acid Ceramidase Impairs Autophagy and Mitochondria Activity in Melanoma Cells

Cutaneous melanoma is often resistant to therapy due to its high plasticity, as well as its ability to metabolise chemotherapeutic drugs. Sphingolipid signalling plays a pivotal role in its progression and metastasis. One of the ways melanoma alters sphingolipid rheostat is via over-expression of lysosomal acid ceramidase (AC), which catalyses the hydrolysis of pro-apoptotic long-chain ceramides into sphingosine and fatty acid. In this report, we examine the role of acid ceramidase in maintaining cellular homeostasis through the regulation of autophagy and mitochondrial activity in melanoma cell lines. We show that under baseline conditions, wild-type melanoma cells had 3-fold higher levels of the autophagy marker, microtubule-associated proteins 1A/1B light chain 3B (LC3 II), compared to AC-null cells. This difference was further magnified after cell starvation. Moreover, we noticed autophagy impairment in A375 AC-null cells, possibly due to local accumulation of non-metabolized ceramides. Nonetheless, we observed that AC-null cells exhibited a significant increase in mitochondrial membrane potential compared to control cells. Consistent with this observation, we found that, after total starvation, ~30% of AC-null cells undergo apoptosis compared to ~6% of wild-type cells. As expected, AC transfection restored viability in A375 AC-null cells. Together, these findings suggest that AC-null melanoma cells change and adapt their metabolism to survive in the absence of AC, although in a way that does not allow them to cope with the stress of nutrient deprivation.