Impact of monomeric, oligomeric and fibrillar alpha-synuclein on astrocyte reactivity and toxicity to neurons
Synucleinopathies are a group of neurodegenerative disorders characterized by the presence of aggregated and fibrillar forms of alpha-synuclein (α-syn). Here, we analyze the effect of different species of α-syn, including monomeric, oligomeric and fibrillar forms of the protein, on rat astrocytes. Astrocytes treated with these distinct forms of α-syn showed an increase in long and thin processes and glial fibrillary acidic protein expression, indicating cell activation, high levels of intracellular oxidants and increased expression of cytokines. Moreover, astrocytes incubated with the different species in...
Source: Biochemical Journal - October 11, 2018 Category: Biochemistry Authors: Chavarria, C., Rodriguez-Bottero, S., Quijano, C., Cassina, P., Souza, J. M. Tags: Research Articles Source Type: research
Substrate-inactivated cyclooxygenase-2 is disposed of by exosomes through the ER-Golgi pathway
Catalysis of arachidonic acid (AA) by cyclooxygenase-2 (COX-2) gives rise to a single product that serves as a precursor for all prostaglandins, which are central mediators of inflammation. Rapid up-regulation of COX-2 expression in response to pro-inflammatory stimuli is a well-characterized means of generating the large pool of prostaglandins necessary for inflammation. However, an efficient inflammatory process must also terminate rapidly and thus requires cessation of COX-2 enzymatic activity and removal of excess protein from the cell. Previous studies showed that COX-2 that has not been exposed to AA (‘naive&rs...
Source: Biochemical Journal - October 11, 2018 Category: Biochemistry Authors: Saadi, E., Tal, S., Barki-Harrington, L. Tags: Research Articles Source Type: research
Collagen degradation in tuberculosis pathogenesis: the biochemical consequences of hosting an undesired guest
The scenario of chemical reactions prompted by the infection by Mycobacterium tuberculosis is huge. The infection generates a localized inflammatory response, with the recruitment of neutrophils, monocytes, and T-lymphocytes. Consequences of this immune reaction can be the eradication or containment of the infection, but these events can be deleterious to the host inasmuch as lung tissue can be destroyed. Indeed, a hallmark of tuberculosis (TB) is the formation of lung cavities, which increase disease development and transmission, as they are sites of high mycobacterial burden. Pulmonary cavitation is associated with antib...
Source: Biochemical Journal - October 11, 2018 Category: Biochemistry Authors: Squeglia, F., Ruggiero, A., Berisio, R. Tags: Review Articles Source Type: research
Biochemical and functional characterization of OsCSD3, a novel CuZn superoxide dismutase from rice
Superoxide dismutases (SODs, EC 1.15.1.1) belong to an important group of antioxidant metalloenzymes. Multiple SODs exist for scavenging of reactive oxygen species (ROS) in different cellular compartments to maintain an intricate ROS balance. The present study deals with molecular and biochemical characterization of CuZn SOD encoded by LOC_Os03g11960 (referred to as OsCSD3), which is the least studied among the four rice isozymes. The OsCSD3 showed higher similarity to peroxisomal SODs in plants. The OsCSD3 transcript was up-regulated in response to salinity, drought, and oxidative stress. Full-length cDNA encoding OsCSD3 ...
Source: Biochemical Journal - October 11, 2018 Category: Biochemistry Authors: Prakash Sanyal, R., Samant, A., Prashar, V., Sharan Misra, H., Saini, A. Tags: Research Articles Source Type: research
An A{beta}42 variant that inhibits intra- and extracellular amyloid aggregation and enhances cell viability
Aggregation and accumulation of the 42-residue amyloid β peptide (Aβ42) in the extracellular matrix and within neuronal cells is considered a major cause of neuronal cell cytotoxicity and death in Alzheimer's disease (AD) patients. Therefore, molecules that bind to Aβ42 and prevent its aggregation are therapeutically promising as AD treatment. Here, we show that a non-self-aggregating Aβ42 variant carrying two surface mutations, F19S and L34P (Aβ42DM), inhibits wild-type Aβ42 aggregation and significantly reduces Aβ42-mediated cell cytotoxicity. In addition, Aβ42DM inhibits the uptak...
Source: Biochemical Journal - October 9, 2018 Category: Biochemistry Authors: Oren, O., Banerjee, V., Taube, R., Papo, N. Tags: Research Articles Source Type: research
IQGAP1 binds the Axl receptor kinase and inhibits its signaling
Axl is a tyrosine kinase receptor that is important for hematopoiesis, the innate immune response, platelet aggregation, engulfment of apoptotic cells and cell survival. Binding of growth arrest-specific protein 6 (Gas6) activates Axl signaling, but the mechanism of inactivation of the Axl receptor is poorly understood. In the present study, we show that IQGAP1 modulates Axl signaling. IQGAP1 is a scaffold protein that integrates cell signaling pathways by binding several growth factor receptors and intracellular signaling molecules. Our in vitro analysis revealed a direct interaction between the IQ domain of IQGAP1 and Ax...
Source: Biochemical Journal - October 9, 2018 Category: Biochemistry Authors: Gorisse, L., Li, Z., Hedman, A. C., Sacks, D. B. Tags: Research Articles Source Type: research
Structure-guided identification of function: role of Capsicum annuum vicilin during oxidative stress
Proteins belonging to cupin superfamily are known to have critical and diverse physiological functions. However, 7S globulins family, which is also a part of cupin superfamily, were undermined as only seed storage proteins. Structure determination of native protein — Vic_CAPAN from Capsicum annuum — was carried out, and its physiological functions were explored after purifying the protein by ammonium sulfate precipitation followed by size exclusion chromatography. The crystal structure of vicilin determined at 2.16 Å resolution revealed two monomers per asymmetric unit which are juxtaposed orthogonal...
Source: Biochemical Journal - October 9, 2018 Category: Biochemistry Authors: Shikhi, M., Nair, D. T., Salunke, D. M. Tags: Research Articles Source Type: research
Revisiting the role of cholesterol in regulating the pore-formation mechanism of Vibrio cholerae cytolysin, a membrane-damaging {beta}-barrel pore-forming toxin
Vibrio cholerae cytolysin (VCC) is a β-barrel pore-forming toxin with potent membrane-damaging cell-killing activity. Previous studies employing the model membranes of lipid vesicles (liposomes) have shown that pore formation by VCC requires the presence of cholesterol in the liposome membranes. However, the exact role of cholesterol in the mode of action of VCC still remains unclear. Most importantly, implication of cholesterol, if any, in regulating the pore-formation mechanism of VCC in the biomembranes of eukaryotic cells remains unexplored. Here, we show that the presence of cholesterol promotes the interaction o...
Source: Biochemical Journal - October 9, 2018 Category: Biochemistry Authors: Kathuria, R., Mondal, A. K., Sharma, R., Bhattacharyya, S., Chattopadhyay, K. Tags: Research Articles Source Type: research
New tools for evaluating protein tyrosine sulfation and carbohydrate sulfation
Sulfation is a common modification of extracelluar glycans and tyrosine residues on proteins, which is important in many signalling pathways and interactions. Existing methods for studying sulfotransferases, the enzymes that catalyse sulfation, are cumbersome and low-throughput. Recent studies published in the Biochemical Journal have repurposed established biochemical assays from the kinase field and applied them to the characterisation of sulfotransferases. Biochemical screening of a library of kinase inhibitors revealed that compounds that target RAF kinases may also be repurposed to inhibit sulfotransferases. Together ...
Source: Biochemical Journal - October 5, 2018 Category: Biochemistry Authors: Yeoh, S., Bayliss, R. Tags: Commentaries Source Type: research
The structure and evolution of eukaryotic chaperonin-containing TCP-1 and its mechanism that folds actin into a protein spring
Actin is folded to its native state in eukaryotic cytosol by the sequential allosteric mechanism of the chaperonin-containing TCP-1 (CCT). The CCT machine is a double-ring ATPase built from eight related subunits, CCT1–CCT8. Non-native actin interacts with specific subunits and is annealed slowly through sequential binding and hydrolysis of ATP around and across the ring system. CCT releases a folded but soft ATP-G-actin monomer which is trapped 80 kJ/mol uphill on the folding energy surface by its ATP-Mg2+/Ca2+ clasp. The energy landscape can be re-explored in the actin filament, F-actin, because ATP hydrolysis...
Source: Biochemical Journal - October 5, 2018 Category: Biochemistry Authors: Willison, K. R. Tags: Review Articles Source Type: research
Mitochondrial-derived reactive oxygen species influence ADP sensitivity, but not CPT-I substrate sensitivity
The mechanisms regulating oxidative phosphorylation during exercise remain poorly defined; however, key mitochondrial proteins, including carnitine palmitoyltransferase-I (CPT-I) and adenine nucleotide translocase, have redox-sensitive sites. Interestingly, muscle contraction has recently been shown to increase mitochondrial membrane potential and reactive oxygen species (ROS) production; therefore, we aimed to determine if mitochondrial-derived ROS influences bioenergetic responses to exercise. Specifically, we examined the influence of acute exercise on mitochondrial bioenergetics in WT (wild type) and transgenic mice (M...
Source: Biochemical Journal - September 28, 2018 Category: Biochemistry Authors: Barbeau, P.-A., Miotto, P. M., Holloway, G. P. Tags: Research Articles Source Type: research
Differential receptor selectivity of the FGF15/FGF19 orthologues determines distinct metabolic activities in db/db mice
Fibroblast growth factors (FGF) 19, 21 and 23 are characterized by being endocrinely secreted and require co-receptor α-klotho or β-klotho (BKL) for binding and activation of the FGF receptors (FGFR). FGF15 is the rodent orthologue of human FGF19, but the two proteins share only 52% amino acid identity. Despite the physiological role of FGF21 and FGF19 being quite different, both lower blood glucose (BG) when administered to diabetic mice. The present study was designed to clarify why two human proteins with distinct physiological functions both lower BG in db/db mice and if the mouse orthologue FGF15 has simila...
Source: Biochemical Journal - September 25, 2018 Category: Biochemistry Authors: Hansen, A. M. K., Vienberg, S. G., Lykkegaard, K., Zhao, X., Tingqing, G., Han, D., Zhang, X., Thogersen, H., Sass-Orum, K., Tagmose, T., Raun, K., Andersen, B. Tags: Research Articles Source Type: research
Isoform-specific AMPK association with TBC1D1 is reduced by a mutation associated with severe obesity
AMP-activated protein kinase (AMPK) is a key regulator of cellular and systemic energy homeostasis which achieves this through the phosphorylation of a myriad of downstream targets. One target is TBC1D1 a Rab-GTPase-activating protein that regulates glucose uptake in muscle cells by integrating insulin signalling with that promoted by muscle contraction. Ser237 in TBC1D1 is a target for phosphorylation by AMPK, an event which may be important in regulating glucose uptake. Here, we show AMPK heterotrimers containing the α1, but not the α2, isoform of the catalytic subunit form an unusual and stable association w...
Source: Biochemical Journal - September 25, 2018 Category: Biochemistry Authors: Thomas, E. C., Hook, S. C., Gray, A., Chadt, A., Carling, D., Al-Hasani, H., Heesom, K. J., Hardie, D. G., Tavare, J. M. Tags: Research Articles Source Type: research
IFN-{gamma}-response mediator GBP-1 represses human cell proliferation by inhibiting the Hippo signaling transcription factor TEAD
Interferon-gamma (IFN-) is a pleiotropic cytokine that exerts important functions in inflammation, infectious diseases, and cancer. The large GTPase human guanylate-binding protein 1 (GBP-1) is among the most strongly IFN--induced cellular proteins. Previously, it has been shown that GBP-1 mediates manifold cellular responses to IFN- including the inhibition of proliferation, spreading, migration, and invasion and through this exerts anti-tumorigenic activity. However, the mechanisms of GBP-1 anti-tumorigenic activities remain poorly understood. Here, we elucidated the molecular mechanism of the human GBP-1-mediated suppre...
Source: Biochemical Journal - September 25, 2018 Category: Biochemistry Authors: Unterer, B., Wiesmann, V., Gunasekaran, M., Sticht, H., Tenkerian, C., Behrens, J., Leone, M., Engel, F. B., Britzen-Laurent, N., Naschberger, E., Wittenberg, T., Stürzl, M. Tags: Research Articles Source Type: research
Chemical validation and optimization of pharmacoperones targeting vasopressin type 2 receptor mutant
A series of compounds formerly identified by high-throughput screening was studied for their ability to serve as pharmacoperones for the vasopressin type 2 receptor (V2R) mutant L83Q, which is known to cause nephrogenic diabetes insipidus (NDI). Three compounds were particularly effective in rerouting the mutant receptor in a concentration-dependent manner, were neither agonists nor antagonists, and displayed low cellular toxicity. Compound 1 was most effective and can be used as a molecular probe for future studies of how small molecules may affect NDI caused by mutant V2R. These compounds, however, failed to rescue the V...
Source: Biochemical Journal - September 25, 2018 Category: Biochemistry Authors: Janovick, J. A., Spicer, T. P., Bannister, T. D., Smith, E., Ganapathy, V., Scampavia, L. Tags: Research Articles Source Type: research
