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Cytosolic AND pH

Vishwanatha K Rao, Gerardo Zavala, Abhijit Deb Roy, Richard E Mains, Betty A Eipper
The biosynthetic and endocytic pathways of secretory cells are characterized by progressive luminal acidification, a process which is crucial for posttranslational modifications and membrane trafficking. This progressive fall in luminal pH is mainly achieved by the vacuolar-type-H+ ATPase (V-ATPase). V-ATPases are large, evolutionarily ancient rotary proton pumps that consist of a peripheral V1 complex, which hydrolyzes ATP, and an integral membrane V0 complex, which transports protons from the cytosol into the lumen...
October 14, 2018: Journal of Cellular Physiology
Keigo Kumagai, Cherilyn A Elwell, Shuji Ando, Joanne N Engel, Kentaro Hanada
Chlamydia trachomatis is an obligate intracellular bacterium that replicates within a membranous compartment, the inclusion, in host cells. Its intracellular life cycle requires host sphingolipids, which are in part acquired through the ER-Golgi localized ceramide transport protein (CERT). The Chlamydia-encoded inclusion membrane protein IncD is composed of two closely linked long hydrophobic domains with their N- and C-termini exposed to the host cytosol. IncD binds directly to the pleckstrin homology (PH) domain of CERT, likely redirecting ceramide to the inclusion...
October 9, 2018: Biochemical and Biophysical Research Communications
Beatrice Riva, Marianna Dionisi, Alberto Potenzieri, Alessia Chiorazzi, Celia Cordero-Sanchez, Roberta Rigolio, Valentina Alda Carozzi, Dmitry Lim, Guido Cavaletti, Paola Marmiroli, Carla Distasi, Armando A Genazzani
Oxaliplatin induced peripheral neurotoxicity is characterized by an acute cold-induced syndrome characterized by cramps, paresthesias/dysesthesias in the distal limbs and perioral region, that develops rapidly and lasts up to one week affecting nearly all the patients as well as by long-lasting symptoms. It has been previously shown that pharmacological or genetic ablation of TRPA1 responses reduces oxaliplatin-induced peripheral neurotoxicity in mouse models. In the present report, we show that treatment with concentrations of oxaliplatin similar to those found in plasma of treated patients leads to an acidification of the cytosol of mouse dorsal root ganglia neurons in culture and this in turn is responsible for sensitization of TRPA1 channels, thereby providing a mechanistic explanation to toxicity of oxaliplatin...
October 10, 2018: Scientific Reports
Tetyana Zhelay, Krystyna B Wieczerzak, Pavani Beesetty, Gerald M Alter, Masayuki Matsushita, J Ashot Kozak
Transient receptor potential cation channel subfamily M member 7 (TRPM7) is an ion channel/protein kinase belonging to the TRP melastatin and eEF2 kinase families.  Under physiological conditions, most native TRPM7 channels are inhibited by cytoplasmic Mg2+ , protons and polyamines.  Currents through these channels (ITRPM7 ) are robustly potentiated when the cell interior is exchanged with low Mg2+ -containing buffers.  ITRPM7 is also potentiated by phosphatidyl inositol bisphosphate (PI(4,5)P2 ) and suppressed by its hydrolysis...
October 10, 2018: Journal of Biological Chemistry
Md Atikur Rahman, Sang-Hoon Lee, Hee Chung Ji, Ahmad Humayan Kabir, Chris Stephen Jones, Ki-Won Lee
Aluminum (Al) toxicity is one of the major limitations that inhibit plant growth and development in acidic soils. In acidic soils (pH < 5.0), phototoxic-aluminum (Al3+ ) rapidly inhibits root growth, and subsequently affects water and nutrient uptake in plants. This review updates the existing knowledge concerning the role of mineral nutrition for alleviating Al toxicity in plants to acid soils. Here, we explored phosphorus (P) is more beneficial in plants under P-deficient, and Al toxic conditions. Exogenous P addition increased root respiration, plant growth, chlorophyll content, and dry matter yield...
October 8, 2018: International Journal of Molecular Sciences
Roy Govrin, Shani Tcherner, Tal Obstbaum, Uri Sivan
Many cells synthesize significant quantities of zwitterionic osmolytes to cope with the osmotic stress induced by excess salt. In addition to their primary role in balancing osmotic pressure, these osmolytes also help stabilize protein structure and restore enzymatic activity compromised by high ionic strength. This osmoprotective effect has been studied extensively but its electrostatic aspects have somehow escaped the main stream. Here, we report that despite their overall neutrality, zwitterions may dramatically affect electrostatic interactions in saline solutions of biological relevance...
October 9, 2018: Journal of the American Chemical Society
Monica M Johnson, Michael A Collier, Ky V Hoang, Erica N Pino, Elizabeth G Graham-Gurysh, Matthew D Gallovic, Md Shamim Hasan Zahid, Naihan Chen, Larry Schlesinger, John S Gunn, Eric M Bachelder, Kristy M Ainslie
Previously we have encapsulated host-directed therapy AR-12 into acetalated dextran (Ace-DEX) microparticles (MPs) to mitigate drug toxicity and passively target phagocytic host cells. Herein, we have improved upon our initial emulsion-based formulation of Ace-DEX MPs encapsulating AR-12 (AR-12/MPs) by improving the drug encapsulation efficiency, evaluating sterilization processes for manufacturing, and understanding cellular and in vivo trafficking of the MPs. By using an alternative solvent system, ethyl acetate, we report an increased encapsulation efficiency of AR-12 while maintaining the pH-responsive degradation kinetics of Ace-DEX MPs...
October 8, 2018: Molecular Pharmaceutics
Srinivas Agurla, Shashibhushan Gahir, Shintaro Munemasa, Yoshiyuki Murata, Agepati S Raghavendra
Drought is one of the abiotic stresses which impairs the plant growth/development and restricts the yield of many crops throughout the world. Stomatal closure is a common adaptation response of plants to the onset of drought condition. Stomata are microscopic pores on the leaf epidermis, which regulate the transpiration/CO2 uptake by leaves. Stomatal guard cells can sense various abiotic and biotic stress stimuli from the internal and external environment and respond quickly to initiate closure under unfavorable conditions...
2018: Advances in Experimental Medicine and Biology
J Dalla Rizza, L M Randall, J Santos, G Ferrer-Sueta, A Denicola
Peroxiredoxins are thiol-dependent peroxidases that function in peroxide detoxification and H2 O2 induced signaling. Among the six isoforms expressed in humans, PRDX1 and PRDX2 share 97% sequence similarity, 77% sequence identity including the active site, subcellular localization (cytosolic) but they hold different biological functions albeit associated with their peroxidase activity. Using recombinant human PRDX1 and PRDX2 the kinetics of oxidation and hyperoxidation with H2 O2 and peroxynitrite were followed by intrinsic fluorescence...
October 3, 2018: Protein Science: a Publication of the Protein Society
Xiu-Jun Yu, Grzegorz J Grabe, Mei Liu, Luís Jaime Mota, David W Holden
Nonflagellar type III secretion systems (nf T3SSs) form a cell surface needle-like structure and an associated translocon that deliver bacterial effector proteins into eukaryotic host cells. This involves a tightly regulated hierarchy of protein secretion. A switch involving SctP and SctU stops secretion of the needle protein. The gatekeeper protein SctW is required for secretion of translocon proteins and controls a second switch to start effector secretion. Salmonella enterica serovar Typhimurium encodes two T3SSs in Salmonella pathogenicity island 1 (SPI-1) and SPI-2...
October 2, 2018: MBio
Yolanda Salinas, Carolin Hoerhager, Alba García-Fernández, Marina Resmini, Félix Sancenón, Ramón Matínez-Máñez, Oliver Brueggemann
Biocompatible ZnS-based nanocrystals capped with 4-mercaptophenylboronic acid (ZnS@B) have been size-designed as excellent pH-responsive gatekeepers on mesoporous silica nanoparticles (MSNs), which encapsulate fluorophore safranin O (S2-Saf) or anticancer drug epirubicin hydrochloride (S2-Epi) for delivery applications in cancer cells. In this novel hybrid system, the gate mechanism consists of reversible pH-sensitive boronate ester moieties linking the nanocrystals directly to the alcohol groups from silica surface scaffold, avoiding tedious intermediate functionalization steps...
October 10, 2018: ACS Applied Materials & Interfaces
Tereza Kučírková, Marek Stiborek, Monika Dúcka, Jarmila Navrátilová, Jelena Bogdanović Pristov, Ana Popović-Bijelić, SneŽana Vojvodić, Jan Preisler, Viktor Kanický, Jan Šmarda, Ivan Spasojević, Petr Beneš
Wedelactone (WL), a plant polyphenolic derivative of coumestan, represents a promising anti-cancer agent. The underlying mechanisms of its action are not fully understood and appear to involve interplay with copper ions. Herein, we examined coordination and redox interactions of WL with Cu2+ in phosphate buffer (pH 7), and in two breast cancer cell lines. EPR, UV-Vis and fluorescence spectroscopy showed that WL and Cu2+ build a coordination complex with 2 : 1 stoichiometry and distorted tetrahedral geometry...
October 17, 2018: Metallomics: Integrated Biometal Science
Kai Sato, Asako Otomo, Mahoko Takahashi Ueda, Yui Hiratsuka, Kyoko Suzuki-Utsunomiya, Junya Sugiyama, Shuji Murakoshi, Shun Mitsui, Suzuka Ono, So Nakagawa, Hui-Fang Shang, Shinji Hadano
Familial amyotrophic lateral sclerosis type 2 is a juvenile autosomal recessive motor neuron disease caused by the mutations in the ALS2 gene. The ALS2 gene product, ALS2/alsin, forms a homophilic oligomer and acts as a guanine nucleotide exchange factor (GEF) for the small GTPase Rab5. This oligomerization is crucial for both Rab5 activation and ALS2-mediated endosome fusion and maturation in cells. Recently, we have shown that pathogenic missense ALS2 mutants retaining the Rab5 GEF activity fail to properly localize to endosomes via Rac1-stimulated macropinocytosis...
September 17, 2018: Journal of Biological Chemistry
Megha Rajendran, Benjamin Claywell, Emily P Haynes, Umi Scales, Chace K Henning, Mathew Tantama
The regulation of pH is essential for proper organelle function, and organelle-specific changes in pH often reflect the dynamics of physiological signaling and metabolism. For example, mitochondrial energy production depends on the proton gradient maintained between the alkaline mitochondrial matrix and neutral cytosol. However, we still lack a quantitative understanding of how pH dynamics are coupled between compartments and how pH gradients are regulated at organelle boundaries. Genetically encoded pH sensors are well suited to address this problem because they can be targeted to specific subcellular locations and they facilitate live, single-cell analysis...
August 31, 2018: ACS Omega
Cyril Favard
The fluorescence recovery after photobleaching (FRAP) technique has been used for decades to measure movements of molecules in two-dimension (2D). Data obtained by FRAP experiments in cell plasma membranes are assumed to be described through a means of two parameters, a diffusion coefficient, D (as defined in a pure Brownian model) and a mobile fraction, M. Nevertheless, it has also been shown that recoveries can be nicely fit using anomalous subdiffusion. Fluorescence recovery after photobleaching (FRAP) at variable radii has been developed using the Brownian diffusion model to access geometrical characteristics of the surrounding landscape of the molecule...
September 5, 2018: Biomolecules
Kai Dong, Zhenzhen Wang, Yan Zhang, Jinsong Ren, Xiaogang Qu
Nowadays, efficient endo/lysosomal escape and the subsequent release of drugs into the cytosol are the major obstacles for nanoplatform-based cancer therapy. Herein, we first report a metal-organic framework-based nanoplatform (doxorubicin@ZIF-8@AS1411) for intracellular environment-responsive endo/lysosomal escape and enhanced cancer therapy. In our system, the nanoplatform was first targeted toward the cancer cells. Then, it was entrapped in endo/lysosomes, where pH-responsive decomposition occurred and abundant Zn ions were released...
September 26, 2018: ACS Applied Materials & Interfaces
Romain Fontaine, Kjetil Hodne, Finn-Arne Weltzien
Electrophysiological investigations of pituitary cells have been conducted in numerous vertebrate species, but very few in teleost fish. Among these, the clear majority have been performed on dissociated primary cells. To improve our understanding of how teleost pituitary cells, behave in a more biologically relevant environment, this protocol shows how to prepare viable brain-pituitary slices using the small freshwater fish medaka (Oryzias latipes). Making the brain-pituitary slices, pH and osmolality of all solutions were adjusted to values found in body fluids of freshwater fish living at 25 to 28 °C...
August 16, 2018: Journal of Visualized Experiments: JoVE
Thingreila Muinao, Mintu Pal, Hari Prasanna Deka Boruah
Efficient extraction of proteins is a great challenge for numerous downstream proteomic analyses. During the protein extraction procedure, it is critical to maintain the conformational stability, integrity, as well as higher yield of the protein. To do so, 5-different lysis buffers of Tris and HEPES have been used as the primary buffering reagents with variable compositions at different concentrations and pH using human cancer cells. In this study, different protein lysates of human breast cancer cells T47D and MDA-MB-231 and ovarian cancer cell PA-1 were subjected to run SDS-PAGE for separation of proteins based on their molecular size, followed by Coomassie blue, silver staining, and immunoblot assays to compare the extraction yield of total cytoplasmic proteins, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the integral membrane protein, integrin β-1...
September 2018: Journal of Biomolecular Techniques: JBT
Yasuyuki Miyake, Patrick Matthias, Yohei Yamauchi
Influenza A virus (IAV) is an enveloped virus with a segmented single-stranded negative-strand RNA genome. In general, the role of virally encapsidated host cell proteins in the viral life cycle is unclear. The virion contains abundant ubiquitin molecules some of which have been identified as unanchored polyubiquitin chains. These ubiquitin chains have been postulated to play a role in recruiting histone deacetylase 6 (HDAC6) to the cytosolic surface of late endosomes (LEs), promoting IAV uncoating via aggresome processing-a cellular machinery that disposes of protein waste...
2018: Methods in Molecular Biology
Nikhil R Yedulla, Akshata R Naik, Keith M Kokotovich, Wenxi Yu, Miriam L Greenberg, Bhanu P Jena
Valproate (VPA), an FDA approved anti-epileptic drug with a half-life of 12-18 h in humans, has been shown to perturb the vacuolar proton pump (vH+ -ATPase) function in yeasts by inhibiting myo-inositol phosphate synthase, the first and rate-limiting enzyme in inositol biosynthesis, thereby resulting in inositol depletion. vH+ -ATPase transfers protons (H+ ) across cell membranes, which help maintain pH gradients within cells necessary for various cellular functions including secretion. This proton pump has a membrane (V0 ) and a soluble cytosolic (V1 ) domain, with C-subunit associated with V1 ...
October 2018: Histochemistry and Cell Biology
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