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Taras Afonyushkin, Olga V Oskolkova, Valery N Bochkov
Receptor tyrosine kinase c-Kit and its ligand stem cell factor (SCF) regulate resident vascular wall cells and recruit circulating progenitors. We tested whether SCF may be induced by oxidized palmitoyl-arachidonoyl-phosphatidylcholine (OxPAPC) known to accumulate in atherosclerotic vessels. Gene expression analysis demonstrated OxPAPC-induced upregulation of SCF mRNA and protein in different types of endothelial cells (ECs). Elevated levels of SCF mRNA were observed in aortas of ApoE-/- knockout mice. ECs produced biologically active SCF because conditioned medium from OxPAPC-treated cells stimulated activation (phosphorylation) of c-Kit in naïve ECs...
January 12, 2018: Angiogenesis
Mitra S Rana, Pramod Kumar, Chul-Jin Lee, Raffaello Verardi, Kanagalaghatta R Rajashankar, Anirban Banerjee
DHHC (Asp-His-His-Cys) palmitoyltransferases are eukaryotic integral membrane enzymes that catalyze protein palmitoylation, which is important in a range of physiological processes, including small guanosine triphosphatase (GTPase) signaling, cell adhesion, and neuronal receptor scaffolding. We present crystal structures of two DHHC palmitoyltransferases and a covalent intermediate mimic. The active site resides at the membrane-cytosol interface, which allows the enzyme to catalyze thioester-exchange chemistry by using fatty acyl-coenzyme A and explains why membrane-proximal cysteines are candidates for palmitoylation...
January 12, 2018: Science
Yan Cui, William F Delaney, Taghi Darroudi, Pingshan Wang
A microwave technique is demonstrated to measure floating giant unilamellar vesicle (GUV) membranes in a 25 μm wide and 18.8 μm high microfluidic channel. The measurement is conducted at 2.7 and 7.9 GHz, at which a split-ring resonator (SRR) operates at odd modes. A 500 nm wide and 100 μm long SRR split gap is used to scan GUVs that are slightly larger than 25 μm in diameter. The smaller fluidic channel induces flattened GUV membrane sections, which make close contact with the SRR gap surface. The used GUVs are synthesized with POPC (16:0-18:1 PC 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine), SM (16:0 Egg Sphingomyelin) and cholesterol at different molecular compositions...
January 11, 2018: Scientific Reports
Barbara Eicher, Drew Marquardt, Frederick A Heberle, Ilse Letofsky-Papst, Gerald N Rechberger, Marie-Sousai Appavou, John Katsaras, Georg Pabst
We measured the effect of intrinsic lipid curvature, J0, on structural properties of asymmetric vesicles made of palmitoyl-oleoyl-phosphatidylethanolamine (POPE; J0<0) and palmitoyl-oleoyl-phosphatidylcholine (POPC; J0∼0). Electron microscopy and dynamic light scattering were used to determine vesicle size and morphology, and x-ray and neutron scattering, combined with calorimetric experiments and solution NMR, yielded insights into leaflet-specific lipid packing and melting processes. Below the lipid melting temperature we observed strong interleaflet coupling in asymmetric vesicles with POPE inner bilayer leaflets and outer leaflets enriched in POPC...
January 9, 2018: Biophysical Journal
Tomoko Mizuguchi, Nobuyuki Matubayasi
All-atom molecular dynamics (MD) simulations are performed to examine the stabilities of a variety of binding configurations of alamethicin, a 20-amino-acid amphipathic peptide, in the bilayers of 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) and 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC). The binding free energy of alamethicin is calculated through a combination of MD simulation and the energy-representation theory of solutions, and it is seen that the transmembrane configuration is stable in both membranes...
January 10, 2018: Journal of Physical Chemistry. B
Roopa Kenoth, Xianqiong Zou, Dhirendra K Simanshu, Helen M Pike, Lucy Malinina, Dinshaw J Patel, Rhoderick E Brown, Ravi Kanth Kamlekar
HET-C2 is a fungal glycolipid transfer protein (GLTP) that uses an evolutionarily-modified GLTP-fold to achieve more focused transfer specificity for simple neutral glycosphingolipids than mammalian GLTPs. Only one of HET-C2's two Trp residues is topologically identical to the three Trp residues of mammalian GLTP. Here, we provide the first assessment of the functional roles of HET-C2 Trp residues in glycolipid binding and membrane interaction. Point mutants HET-C2W208F, HET-C2W208A and HET-C2F149Y all retained >90% activity and 80-90% intrinsic Trp fluorescence intensity; whereas HET-C2F149A transfer activity decreased to ~60% but displayed ~120% intrinsic Trp emission intensity...
January 3, 2018: Biochimica et Biophysica Acta
Bin Tang, Jin-Guo Zhang, Hong-Yong Tan, Xi-Qing Wei
Chronic heart failure (CHF) is the end-stage of many cardiovascular diseases and severely affects the patients' lifespan. Inhibiting ventricular remodeling is thus a primary treatment target for CHF patients. Astragaloside IV (AS-IV) can improve cardiac function and protect myocardial cells. The study aims to investigate the effects of AS-IV on ventricular remodeling and explore its role in regulating energy metabolism using a rat CHF model. Sprague Dawley rats were divided into 5 groups (N=20 per group):  CHF + benazepril hydrochloride, CHF + low-dose (30 mg...
January 4, 2018: Bioscience Reports
Ning Xiang, Yuan Lyu, Xiao Zhu, Ganesan Narsimhan
Some amyloid related proteins/peptides are involved in aggregation and pore formation in phospholipid membranes (cell membranes), which result in a variety of neurological disorders such as Alzheimer's disease, Parkinson's disease and Huntington disease. In this research, the mechanism of pore formation by β amyloid (Aβ) peptides was investigated using molecular dynamics simulation by simulating the interaction of the Aβ(11-42) peptide, with a lipid membrane and the potential of the mean force of interaction was evaluated...
January 4, 2018: Physical Chemistry Chemical Physics: PCCP
Masato Niwa, Tasuku Hirayama, Ikumi Oomoto, Dan Ohtan Wang, Hideko Nagasawa
Iron is an essential transition metal species for all living organisms and plays various physiologically important roles on the basis of its redox activity; accordingly, the disruption of iron homeostasis triggers oxidative stress and cellular damage. Therefore, cells have developed a sophisticated iron-uptake machinery to acquire iron while protecting cells from uncontrolled oxidative damage during the uptake process. To examine the detailed mechanism of iron uptake while controlling the redox status, it is necessary to develop useful methods with redox state-selectivity, sensitivity, and organelle-specificity to monitor labile iron, which is weakly bound to subcellular ligands...
January 3, 2018: ACS Chemical Biology
Ewa Stypulkowski, Irfan A Asangani, Eric S Witze
Asymmetric cell division results in two distinctly fated daughter cells. A molecular hallmark of asymmetric division is the unequal partitioning of cell fate determinants. We have previously established that growth factor signaling promotes protein depalmitoylation to foster polarized protein localization, which, in turn, drives migration and metastasis. We report protein palmitoylation as a key mechanism for the asymmetric partitioning of the cell fate determinants Numb and β-catenin through the activity of the depalmitoylating enzyme APT1...
January 2, 2018: Science Signaling
Xinxin Gao, Rami N Hannoush
Protein palmitoylation plays diverse roles in regulating the trafficking, stability, and activity of cellular proteins. The advent of click chemistry has propelled the field of protein palmitoylation forward by providing specific, sensitive, rapid, and easy-to-handle methods for studying protein palmitoylation. This year marks the 10th anniversary since the first click chemistry-based fatty acid probes for detecting protein lipid modifications were reported. The goal of this review is to highlight key biological advancements in the field of protein palmitoylation during the past 10 years...
December 18, 2017: Cell Chemical Biology
Yujin Kim, Hayoung Yang, Jeongki Min, Young-Jun Park, Seung Hun Jeong, Sung-Wuk Jang, Sungbo Shim
Normal extracellular secretion of nephroblastoma overexpressed (NOV, also known as CCN3) is important for the adhesion, migration, and differentiation of cells. In previous studies, we have shown that the intracellular accumulation of CCN3 inhibits the growth of prominent neurons. Increased intracellular CCN3 can be induced through various processes, such as transcription, detoxification, and posttranslational modification. In general, posttranslational modifications are very important for protein secretion...
December 26, 2017: Biochemical and Biophysical Research Communications
Gregory J Fredericks, FuKun W Hoffmann, Robert J Hondal, Sharon Rozovsky, Johann Urschitz, Peter R Hoffmann
Selenoprotein K (SELENOK) is a selenocysteine (Sec)-containing protein localized in the endoplasmic reticulum (ER) membrane where it interacts with the DHHC6 (where single letter symbols represent Asp-His-His-Cys amino acids) enzyme to promote protein acyl transferase (PAT) reactions. PAT reactions involve the DHHC enzymatic capture of palmitate via a thioester bond to cysteine (Cys) residues that form an unstable palmitoyl-DHHC intermediate, followed by transfer of palmitate to Cys residues of target proteins...
December 29, 2017: Antioxidants (Basel, Switzerland)
Kshatresh Dutta Dubey, Sason Shaik
The driving force for the electron transfer (ET) step in the catalytic cycle of cytochrome P450BM3, is investigated using three sets of 1 µs molecular dynamic simulations for the resting state of P450 in complex with the flavin (FMN) in the reductase domain. These sets involve: (i) substrate-free (SF), (ii) substrate (N-palmitoyl glycine, i.e NPG)-bound (SB), and (iii) SB with the semiquinone radical-anion (SQ-) of FMN. Starting from the X-ray structure of the SF heme domain, we observe that the α1 helix (of the reductase) and the C helix (of the heme) undergo reorientation to a parallel orientation, which is the thermochemically stable form...
December 26, 2017: Journal of the American Chemical Society
Michael K Hsin, Ricardo Zamel, Marcelo Cypel, David Wishart, Beomsoo Han, Shaf Keshavjee, Mingyao Liu
OBJECTIVE: To identify potential biomarkers during ex vivo lung perfusion (EVLP) using metabolomics approach. SUMMARY BACKGROUND DATA: EVLP increases the number of usable donor lungs for lung transplantation (LTx) by physiologic assessment of explanted marginal lungs. The underlying paradigm of EVLP is the normothermic perfusion of cadaveric lungs previously flushed and stored in hypothermic preservation fluid, which allows the resumption of active cellular metabolism and respiratory function...
January 2018: Annals of Surgery
Sang Joon Won, Melanie Cheung See Kit, Brent R Martin
Protein depalmitoylation describes the removal of thioester-linked long chain fatty acids from cysteine residues in proteins. For many S-palmitoylated proteins, this process is promoted by acyl protein thioesterase enzymes, which catalyze thioester hydrolysis to solubilize and displace substrate proteins from membranes. The closely related enzymes acyl protein thioesterase 1 (APT1; LYPLA1) and acyl protein thioesterase 2 (APT2; LYPLA2) were initially identified from biochemical assays as G protein depalmitoylases, yet later were shown to accept a number of S-palmitoylated protein and phospholipid substrates...
December 14, 2017: Critical Reviews in Biochemistry and Molecular Biology
David Cucchiari, Irene Colombo, Ottavia Amato, Manuel Alfredo Podestà, Francesco Reggiani, Rossella Valentino, Irene Faravelli, Silvia Testolin, Maurizio Moggio, Salvatore Badalamenti
Rhabdomyolysis is a common cause of acute kidney injury (AKI) that is usually triggered by trauma. However, less common causes of rhabdomyolysis may precipitate AKI as well, possibly representing a diagnostic challenge even for the experienced nephrologist. Genetic defects of muscle metabolism represent one of these causes and can be overlooked in adults, since these diseases usually become apparent in childhood. We present here a case in which an adult patient with severe exertional rhabdomyolysis leading to AKI was finally diagnosed with a genetic defect of lipid metabolism...
December 12, 2017: CEN Case Reports
Sara Alves, Leire Neiri, Susana Rodrigues Chaves, Selma Vieira, Dário Trindade, Stephen Manon, Veronica Dominguez, Belen Pintado, Veronique Jonckheere, Petra Van Damme, Rui Duarte Silva, Rafael Aldabe, Manuela Côrte-Real
The pro-apoptotic Bax protein is the main effector of mitochondrial permeabilization during apoptosis. Bax is controlled at several levels, including post-translational modifications such as phosphorylation and S-palmitoylation. However, little is known about the contribution of other protein modifications to Bax activity. Here, we used heterologous expression of human Bax in yeast to study the involvement of N-terminal acetylation by yNaa20p (yNatB) on Bax function. We found that human Bax is N-terminal (Nt-)acetylated by yNaa20p and that Nt-acetylation of Bax is essential to maintain Bax in an inactive conformation in the cytosol of yeast and Mouse Embryonic Fibroblast (MEF) cells...
December 9, 2017: International Journal of Biochemistry & Cell Biology
Mélanie Campana, Lara Bellini, Claude Rouch, Latif Rachdi, Nicolas Coant, Noémie Butin, Cécile L Bandet, Erwann Philippe, Kelly Meneyrol, Nadim Kassis, Julien Dairou, Eric Hajduch, Benoit Colsch, Christophe Magnan, Hervé Le Stunff
OBJECTIVES: Hypothalamic lipotoxicity has been shown to induce central insulin resistance and dysregulation of glucose homeostasis; nevertheless, elucidation of the regulatory mechanisms remains incomplete. Here, we aimed to determine the role of de novo ceramide synthesis in hypothalamus on the onset of central insulin resistance and the dysregulation of glucose homeostasis induced by obesity. METHODS: Hypothalamic GT1-7 neuronal cells were treated with palmitate...
November 7, 2017: Molecular Metabolism
Appala Venkata Ramana Murthy, Fanny Guyomarc'h, Christelle Lopez
Ceramides are minor structural components of membranes involved in biological functions. In the milk fat globule membrane (MFGM), ceramides are susceptible to affect the lateral packing of polar lipids, especially the milk sphingomyelin (MSM). To investigate this, palmitoylceramide (PCer) was added to MSM/DOPC (dioleoylphosphatidylcholine) in order to form hydrated lipid bilayers. Differential scanning calorimetry evidenced interactions of PCer with the MSM in the solid-ordered phase to form MSM/PCer structures with a higher thermostability than MSM...
December 8, 2017: Biochimica et Biophysica Acta
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