HSP70 induces liver X receptor pathway activation and cholesterol reduction in vitro and in vivo

Objective: Heat Shock Proteins (HSPs) maintain cellular homeostasis under stress. HSP70 represents a major stress-inducible family member and has been identified as a druggable target in inherited cholesterol-sphingolipid storage diseases. We investigated if HSP70 modulates cholesterol accumulation in more common conditions related to atherogenesis. Methods: We studied the effects of recombinant HSP70 in cholesterol-laden primary macrophages from human blood donors and pharmacological HSP70 upregulation in high-cholesterol diet fed zebrafish. Results: Recombinant HSP70 facilitated cholesterol removal from primary human macrophage foam cells. RNA sequencing revealed that HSP70 induced a robust transcriptional re-programming, including upregulation of key targets of liver X receptors (LXR), master regulators of whole-body cholesterol removal. Mechanistically, HSP70 interacted with the macrophage LXRalpha promoter, increased LXRalpha and its target mRNAs, and led to elevated levels of key proteins facilitating cholesterol efflux, including ATP-binding cassette transporters A1 and G1. Pharmacological augmentation of endogenous HSP70 in high-cholesterol diet fed zebrafish activated LXR and its target mRNAs and reduced cholesterol storage at the whole organism level. Conclusion: These data demonstrate that HSP70 exerts a cholesterol lowering effect in primary human cells and animals and uncover a nuclear action of HSP70 in mediating cross-talk between HSP and LXR transcriptional regulation. (C) 2019 The Authors. Published by Elsevier GmbH.Peer reviewe

Membrane fluidity matters: Hyperthermia from the aspects of lipids and membranes

Hyperthermia is a promising treatment modality for cancer in combination both with radio- and chemotherapy. In spite of its great therapeutic potential, the underlying molecular mechanisms still remain to be clarified. Due to lipid imbalances and 'membrane defects' most of the tumour cells possess elevated membrane fluidity. However, further increasing membrane fluidity to sensitise to chemo-or radiotherapy could have some other effects. In fact, hyperfluidisation of cell membrane induced by membrane fluidiser initiates a stress response as the heat shock protein response, which may modulate positively or negatively apoptotic cell death. Overviewing some recent findings based on a technology allowing direct imaging of lipid rafts in live cells and lipidomics, novel aspects of the intimate relationship between the 'membrane stress' of tumour cells and the cellular heat shock response will be highlighted. Our findings lend support to both the importance of membrane remodelling and the release of lipid signals initiating stress protein response, which can operate in tandem to control the extent of the ultimate cellular thermosensitivity. Overall, we suggest that the fluidity variable of membranes should be used as an independent factor for predicting the efficacy of combinational cancer therapies

Examination of the Effect of Triangular Plate on the Performances of Reverse Rotating Dual Savonius Wind Turbines

In the present study, the performance of the Savonius wind turbine in designs with dual turbines rotating opposite to each other was examined. To improve the performance of the Savonius wind turbine in the dual turbine design, a triangular plate was placed in front of the turbines. The effects of the geometric parameters of this triangular plate which was placed on the turbine performance were studied. The numerical analyses performed were confirmed by the experimental data of a previous study in the literature. The performance values of Savonius wind turbines were analyzed by numerical analysis, the accuracy of which was proven by experimental data. ANSYS Fluent, a computational fluid dynamics (CFD) program, was used for the performance analysis. In the first stage, the maximum power coefficient (Cp) of the conventional Savonius wind turbine was obtained around 0.17. With the optimum geometric parameter studies, the maximum power coefficient of the Savonius wind turbine in the triangular plate dual turbine design was determined to be around 0.22. Thus, it was found that the power coefficient obtained by a single Savonius wind turbine in a triangular plate dual turbine design was around 30% higher compared to the power coefficient of the conventional Savonius wind turbine

Concerted regulation of NPC2 binding to endosomal/lysosomal membranes by bis(monoacylglycero)phosphate and sphingomyelin

Niemann-Pick Protein C2 (NPC2) is a small soluble protein critical for cholesterol transport within and from the lysosome and the late endosome. Intriguingly, NPC2-mediated cholesterol transport has been shown to be modulated by lipids, yet the molecular mechanism of NPC2-membrane interactions has remained elusive. Here, based on an extensive set of atomistic simulations and free energy calculations, we clarify the mechanism and energetics of NPC2-membrane binding and characterize the roles of physiologically relevant key lipids associated with the binding process. Our results capture in atomistic detail two competitively favorable membrane binding orientations of NPC2 with a low interconversion barrier. The first binding mode (Prone) places the cholesterol binding pocket in direct contact with the membrane and is characterized by membrane insertion of a loop (V59-M60-G61-I62-P63-V64P65). This mode is associated with cholesterol uptake and release. On the other hand, the second mode (Supine) places the cholesterol binding pocket away from the membrane surface, but has overall higher membrane binding affinity. We determined that bis(monoacylglycero) phosphate (BMP) is specifically required for strong membrane binding in Prone mode, and that it cannot be substituted by other anionic lipids. Meanwhile, sphingomyelin counteracts BMP by hindering Prone mode without affecting Supine mode. Our results provide concrete evidence that lipids modulate NPC2-mediated cholesterol transport either by favoring or disfavoring Prone mode and that they impose this by modulating the accessibility of BMP for interacting with NPC2. Overall, we provide a mechanism by which NPC2-mediated cholesterol transport is controlled by the membrane composition and how NPC2-lipid interactions can regulate the transport rate.Peer reviewe

Evaluation of the Anticancer and Biological Activities of Istaroxime via Ex Vivo Analyses, Molecular Docking and Conceptual Density Functional Theory Computations

Cancer is a disease that occurs as a result of abnormal or uncontrolled growth of cells due to DNA damage, among many other causes. Certain cancer treatments aim to increase the excess of DNA breaks to such an extent that they cannot escape from the general mechanism of cell checkpoints, leading to the apoptosis of mutant cells. In this study, one of the Sarco-endoplasmic reticulum Ca2+ATPase (SERCA2a) inhibitors, Istaroxime, was investigated. There has been very limited number of articles so far reporting Istaroxime’s anticancer activity; thus, we aimed to evaluate the anticancer effects of Istaroxime by cell proliferation assay and revealed the cytotoxic activity of the compound. We further determined the interaction of Istaroxime with topoisomerase enzymes through enzyme activity tests and detailed molecular modeling analysis. Istaroxime exhibited an antiproliferative effect on A549, MCF7, and PC3 cell lines and inhibited Topoisomerase I, suggesting that Istaroxime can act as a Topoisomerase I inhibitor under in vitro conditions. Molecular docking analysis supported the experimental observations. A chemical reactivity analysis of the Istaroxime molecule was made in the light of Density Functional Theory computations. For this aim, important chemical reactivity descriptors such as hardness, electronegativity, and electrophilicity were computed and discussed as detailed

Changes in serum obestatin, preptin and ghrelins in patients with Gestational Diabetes Mellitus

Objectives: The present study aims to establish the levels of acylated ghrelin, desacylated ghrelin, obestatin and preptin, during pregnancy and the postpartum period in pregnant women with Gestational Diabetes Mellitus (GDM) and healthy pregnancy women

Effects of NSC and 2-Brp on HSP25 and HSP70 protein levels under heat shock conditions.

<p>Cells were treated as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089136#pone-0089136-g005" target="_blank"><b>Figure 5</b></a> and were collected after an overnight recovery at 37°C. (<b>A</b>) Western blotting was performed for equal amounts of total protein samples. Membranes were probed with anti-HSP25, anti-HSP70 and anti-Gapdh antibodies. (<b>B</b>) The band intensities of protein expression levels were quantitated and normalized to Gapdh. In calculations of fold changes, the protein levels of 41.5°C samples were taken as 100. Data are means ± SD, n = 3.</p