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Lee GH, Oh SY, Yeo KJ, Ferdous T, Cho M, Paik Y. Solid-state 31P NMR investigation on the status of guanine nucleotides in paclitaxel-stabilized microtubules. Magn Reson Chem 2015; 53:330-336. [PMID: 25808514 DOI: 10.1002/mrc.4183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 08/20/2014] [Accepted: 10/15/2014] [Indexed: 06/04/2023]
Abstract
Microtubule dynamics is a target for many chemotherapeutic drugs. In order to understand the biochemical effects of paclitaxel on the GTPase activity of tubulin, the status of guanine nucleotides in microtubules was investigated by (31)P cross-polarization magic angle spinning (CPMAS) NMR. Microtubules were freshly prepared in vitro in the presence of paclitaxel and then lyophilized in sucrose buffer for solid-state NMR experiments. A (31)P CPMAS NMR spectrum with the SNR of 25 was successfully acquired from the lyophilized microtubule sample. The broadness of the (31)P spectral lines in the spectrum indicates that the molecular environments around the guanine nucleotides inside tubulin may not be as crystalline as reported by many diffraction studies. Deconvolution of the spectrum into four spectral components was carried out in comparison with the (31)P NMR spectra obtained from five control samples. The spectral analysis suggested that about 13% of the nucleotides were present as GTP and 37% as GDP in the β-tubulin (E-site) of the microtubules. It was found that most of the GDPs were present as GDP-Pi complex in the microtubules, which seems to be one of the effects of paclitaxel binding.
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Affiliation(s)
- Ga Hyang Lee
- Daegu Center, Korea Basic Science Institute, 80 Daehakro, Bukgu, Daegu, 702-701, Korea; Ochang Center, Korea Basic Science Institute, 162 Yeongudanjiro, Ochangeup, Cheongwongun, Chungcheongbukdo, 363-883, Korea
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Lin HY, Liu JH, Cheng KL, Lin JY, Liu NR, Meng M. A novel binding of GTP stabilizes the structure and modulates the activities of human phosphoglucose isomerase/autocrine motility factor. Biochem Biophys Rep 2015; 2:14-22. [PMID: 29124141 PMCID: PMC5668625 DOI: 10.1016/j.bbrep.2015.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 04/13/2015] [Accepted: 04/13/2015] [Indexed: 11/29/2022] Open
Abstract
Phosphoglucose isomerase (PGI) catalyzes the interconversion between glucose 6-phosphate and fructose 6-phosphate in the glycolysis pathway. In mammals, the enzyme is also identical to the extracellular proteins neuroleukin, tumor-secreted autocrine motility factor (AMF) and differentiation and maturation mediator for myeloid leukemia. Hereditary deficiency of the enzyme causes non-spherocytic hemolytic anemia in human. In the present study, a novel interaction between GTP and human PGI was corroborated by UV-induced crosslinking, affinity purification and kinetic study. GTP not only inhibits the isomerization activity but also compromises the AMF function of the enzyme. Kinetic studies, including the Yonetani-Theorell method, suggest that GTP is a competitive inhibitor with a Ki value of 63 μM and the GTP-binding site partially overlaps with the catalytic site. In addition, GTP stabilizes the structure of human PGI against heat- and detergent-induced denaturation. Molecular modelling and dynamic simulation suggest that GTP is bound in a syn-conformation with the γ-phosphate group located near the phosphate-binding loop and the ribose moiety positioned away from the active-site residues.
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Affiliation(s)
- Hua-Yang Lin
- Graduate Institute of Biotechnology, National Chung Hsing University (NCHU), 250 Kuo-Kuang Road, Taichung, Taiwan 40227
| | - Jyung-Hurng Liu
- Graduate Institute of Genomics and Bioinformatics, NCHU, Taichung, Taiwan 40227.,Agricultural Biotechnology Center (ABC), NCHU, Taichung, Taiwan 40227.,Rong Hsing Research Center for Translational Medicine, NCHU, Taichung, Taiwan 40227
| | - Ka-Lik Cheng
- Graduate Institute of Biotechnology, National Chung Hsing University (NCHU), 250 Kuo-Kuang Road, Taichung, Taiwan 40227
| | - Jia-Yun Lin
- Graduate Institute of Biotechnology, National Chung Hsing University (NCHU), 250 Kuo-Kuang Road, Taichung, Taiwan 40227
| | - Ni-Rung Liu
- Graduate Institute of Biotechnology, National Chung Hsing University (NCHU), 250 Kuo-Kuang Road, Taichung, Taiwan 40227
| | - Menghsiao Meng
- Graduate Institute of Biotechnology, National Chung Hsing University (NCHU), 250 Kuo-Kuang Road, Taichung, Taiwan 40227
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Val AL, Gomes KRM, de Almeida-Val VMF. Rapid regulation of blood parameters under acute hypoxia in the Amazonian fish Prochilodus nigricans. Comp Biochem Physiol A Mol Integr Physiol 2015; 184:125-31. [PMID: 25737030 DOI: 10.1016/j.cbpa.2015.02.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 11/25/2022]
Abstract
Prochilodus nigricans, locally known as curimatã, is an Amazonian commercial fish that endures adverse environmental conditions, in particular low dissolved oxygen, during its migration. Poorer environmental conditions are expected in the near future. Prochilodus nigricans overcomes current seasonal and diurnal changes in dissolved oxygen by adjusting erythrocytic levels of ATP and GTP, modulators of Hb-O2 affinity. Will this fish species be endangered under more extreme environmental conditions as hypoxia and acidification tend to occur in a shorter period of time? As P. nigricans does not exhibit any apparent morphological alterations to exploit the air-water interface, it must rely on fast adjustments of blood properties. To investigate this aspect, basic hematology indices, pHe, pHi, plasma lactate, erythrocytic levels of ATP and GTP and functional properties of the hemolysate of P. nigricans were analyzed over a period of 6h in hypoxia and subsequent recovery in normoxia. The levels of erythrocytic GTP were four times higher than ATP and were reduced to ¼ of the original level after 3h under hypoxia. Erythrocytic levels of ATP were unaffected over the experimental period. All other analyzed blood parameters exhibited a time-course change in animals under hypoxia and returned to normoxic levels. Considering the hemolysate functional properties and the ability to regulate the above mentioned blood characteristics, P. nigricans is able to endure short-term changes in dissolved oxygen.
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Affiliation(s)
- Adalberto Luis Val
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Ave Andre Araujo, 2936, Manaus, AM, 69080-971, Brazil.
| | - Katia Regina Maruyama Gomes
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Ave Andre Araujo, 2936, Manaus, AM, 69080-971, Brazil.
| | - Vera Maria Fonseca de Almeida-Val
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Ave Andre Araujo, 2936, Manaus, AM, 69080-971, Brazil.
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Wang S, Moustaid-Moussa N, Chen L, Mo H, Shastri A, Su R, Bapat P, Kwun I, Shen CL. Novel insights of dietary polyphenols and obesity. J Nutr Biochem. 2014;25:1-18. [PMID: 24314860 DOI: 10.1016/j.jnutbio.2013.09.001] [Citation(s) in RCA: 594] [Impact Index Per Article: 59.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 07/15/2013] [Accepted: 09/04/2013] [Indexed: 12/14/2022]
Abstract
The prevalence of obesity has steadily increased over the past three decades both in the United States and worldwide. Recent studies have shown the role of dietary polyphenols in the prevention of obesity and obesity-related chronic diseases. Here, we evaluated the impact of commonly consumed polyphenols, including green tea catechins, especially epigallocatechin gallates, resveratrol and curcumin, on obesity and obesity-related inflammation. Cellular studies demonstrated that these dietary polyphenols reduce viability of adipocytes and proliferation of preadipocytes, suppress adipocyte differentiation and triglyceride accumulation, stimulate lipolysis and fatty acid β-oxidation, and reduce inflammation. Concomitantly, the polyphenols modulate signaling pathways including the adenosine-monophosphate-activated protein kinase, peroxisome proliferator activated receptor γ, CCAAT/enhancer binding protein α, peroxisome proliferator activator receptor gamma activator 1-alpha, sirtuin 1, sterol regulatory element binding protein-1c, uncoupling proteins 1 and 2, and nuclear factor-κB that regulate adipogenesis, antioxidant and anti-inflammatory responses. Animal studies strongly suggest that commonly consumed polyphenols described in this review have a pronounced effect on obesity as shown by lower body weight, fat mass and triglycerides through enhancing energy expenditure and fat utilization, and modulating glucose hemostasis. Limited human studies have been conducted in this area and are inconsistent about the antiobesity impact of dietary polyphenols probably due to the various study designs and lengths, variation among subjects (age, gender, ethnicity), chemical forms of the dietary polyphenols used and confounding factors such as other weight-reducing agents. Future randomized controlled trials are warranted to reconcile the discrepancies between preclinical efficacies and inconclusive clinic outcomes of these polyphenols.
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Abstract
Recently, we used in vitro selection to identify a new class of naturally occurring GTP aptamer called the G motif. Here we report the discovery and characterization of a second class of naturally occurring GTP aptamer, the “CA motif.” The primary sequence of this aptamer is unusual in that it consists entirely of tandem repeats of CA-rich motifs as short as three nucleotides. Several active variants of the CA motif aptamer lack the ability to form consecutive Watson-Crick base pairs in any register, while others consist of repeats containing only cytidine and adenosine residues, indicating that noncanonical interactions play important roles in its structure. The circular dichroism spectrum of the CA motif aptamer is distinct from that of A-form RNA and other major classes of nucleic acid structures. Bioinformatic searches indicate that the CA motif is absent from most archaeal and bacterial genomes, but occurs in at least 70 percent of approximately 400 eukaryotic genomes examined. These searches also uncovered several phylogenetically conserved examples of the CA motif in rodent (mouse and rat) genomes. Together, these results reveal the existence of a second class of naturally occurring GTP aptamer whose sequence requirements, like that of the G motif, are not consistent with those of a canonical secondary structure. They also indicate a new and unexpected potential biochemical activity of certain naturally occurring tandem repeats.
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Affiliation(s)
- Edward A Curtis
- Department of Chemistry and Chemical Biology and Howard Hughes Medical Institute; Harvard University; Cambridge, MA USA
| | - David R Liu
- Department of Chemistry and Chemical Biology and Howard Hughes Medical Institute; Harvard University; Cambridge, MA USA
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Polesskaya O, Wong C, Lebron L, Chamberlain JM, Gelbard HA, Goodfellow V, Kim M, Daiss JL, Dewhurst S. MLK3 regulates fMLP-stimulated neutrophil motility. Mol Immunol 2014; 58:214-22. [PMID: 24389043 PMCID: PMC3946811 DOI: 10.1016/j.molimm.2013.11.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 11/20/2013] [Accepted: 11/23/2013] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Mixed lineage kinase 3 (MLK3) is part of the intracellular regulatory system that connects extracellular cytokine or mitogen signals received through G-protein coupled receptors to changes in gene expression. MLK3 activation stimulates motility of epithelial cells and epithelial-derived tumor cells, but its role in mediating the migration of other cell types remains unknown. Since neutrophils play a crucial role in innate immunity and contribute to the pathogenesis of several diseases, we therefore examined whether MLK3 might regulate the motility of mouse neutrophils responding to a chemotactic stimulus, the model bacterial chemoattractant fMLP. METHODS The expression of Mlk3 in mouse neutrophils was determined by immunocytochemistry and by RT-PCR. In vitro chemotaxis in a gradient of fMLP, fMLP-stimulated random motility, fMLP-stimulated F-actin formation were measured by direct microscopic observation using neutrophils pre-treated with a novel small molecule inhibitor of MLK3 (URMC099) or neutrophils obtained from Mlk3-/- mice. In vivo effects of MLK3 inhibition were measured by counting the fMLP-induced accumulation of neutrophils in the peritoneum following pre-treatment with URMC099 in wild-type C57Bl/6 or mutant Mlk3-/- mice. RESULTS The expression of Mlk3 mRNA and protein was observed in neutrophils purified from wild-type C57Bl/6 mice but not in neutrophils from mutant Mlk3-/- mice. Chemotaxis by wild-type neutrophils induced by a gradient of fMLP was reduced by pre-treatment with URMC099. Neutrophils from C57Bl/6 mice pretreated with URMC099 and neutrophils from Mlk3-/- mice moved far less upon fMLP-stimulation and did not form F-actin as readily as untreated neutrophils from C57Bl/6 controls. In vivo recruitment of neutrophils into the peritoneum by fMLP was significantly reduced in wild-type mice treated with URMC099, as well as in untreated Mlk3-/- mice-thereby confirming the role of MLK3 in neutrophil migration. CONCLUSIONS Mlk3 mRNA is expressed in murine neutrophils. Genetic or pharmacologic inhibition of MLK3 blocks fMLP-mediated motility of neutrophils both in vitro and in vivo, suggesting that MLK3 may be a therapeutic target in human diseases characterized by exuberant neutrophil migration.
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Affiliation(s)
- Oksana Polesskaya
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA.
| | - Christopher Wong
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA; Carleton College, 1N College Street, Northfield, MN 55057, USA
| | - Luis Lebron
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA
| | - Jeffrey M Chamberlain
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA
| | - Harris A Gelbard
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA; Center for Neural Development and Disease, and Departments of Pediatrics and Neurology, University of Rochester Medical Center, Rochester 14642, NY, USA
| | - Val Goodfellow
- Califia Bio Inc., 11575 Sorrento Valley Road, San Diego, CA, USA
| | - Minsoo Kim
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA; David H. Smith Center for Vaccine Biology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA
| | - John L Daiss
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA; Center for Musculoskeletal Research, and Department of Orthopaedics, University of Rochester Medical Center, 601 Elmwood Avenue, Box 672, Rochester 14642, NY, USA
| | - Stephen Dewhurst
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642 NY, USA.
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Wang N, Luo LL, Xu JJ, Xu MY, Zhang XM, Zhou XL, Liu WJ, Fu YC. Obesity accelerates ovarian follicle development and follicle loss in rats. Metabolism 2014; 63:94-103. [PMID: 24135502 DOI: 10.1016/j.metabol.2013.09.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Studies have shown that excess body fat negatively affects reproductive functions in females. However, whether obesity affects the ovarian follicle development and ovarian lifespan and the underlying mechanism has not been well elucidated. The aim of the present study was to investigate the association between obesity and ovarian follicle development. METHODS Adult female Sprague-Dawley rats (n = 36) were randomly divided into three groups: the normal control (NC) group, the caloric restriction (CR) group (fed 70% food of the NC group) and the high-fat diet (HF) group. They were maintained on these regimens for 18 weeks. RESULTS The body weight, ovary weight and visceral fat in the HF group were significantly higher than those in the NC group and the CR group at the end of treatment. Histological analysis showed that the HF rats had significantly less number and percentage of primordial follicles, but greater number and percentage of developing and atretic follicles than the NC rats and CR rats. Western blot analysis demonstrated that the level of mTORC1 and p-S6K1 proteins significantly increased in the ovaries of HF rats, whereas that of SIRT1, SIRT6, FOXO3a and NRF-1 decreased compared to the NC rats. In contrast, the expression of mTORC1 and p-S6K1 dramatically declined, while that of SIRT1, SIRT6, FOXO3a and NRF1 increased in the ovaries of CR rats. CONCLUSIONS Our study suggests that the HF diet induced obesity may accelerate the ovarian follicle development and rate of follicle loss through activating mTOR and suppressing SIRT1 signaling, thus leading to POF, and that CR may inhibit the activation of primordial follicles, follicular development and loss, thus extending the ovarian lifespan through suppressing mTOR and activating SIRT1 signaling.
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Affiliation(s)
- Na Wang
- Laboratory of Cell Senescence, Shantou University Medical College, Xinling Road 22, Shantou 515041, P.R. China
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Wakil SM, Ramzan K, Abuthuraya R, Hagos S, Al-Dossari H, Al-Omar R, Murad H, Chedrawi A, Al-Hassnan ZN, Finsterer J, Bohlega S. Infantile-onset ascending hereditary spastic paraplegia with bulbar involvement due to the novel ALS2 mutation c.2761C>T. Gene 2013; 536:217-20. [PMID: 24315819 DOI: 10.1016/j.gene.2013.11.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 11/14/2013] [Accepted: 11/18/2013] [Indexed: 11/17/2022]
Abstract
Recessive mutations in the alsin gene cause three clinically distinct motor neuron diseases: juvenile amyotrophic lateral sclerosis (ALS2), juvenile primary lateral sclerosis (JPLS) and infantile-onset ascending hereditary spastic paraplegia (IAHSP). A total of 23 different ALS2 mutations have been described for the three disorders so far. Most of these mutations result in a frameshift leading to a premature truncation of the alsin protein. We report the novel ALS2 truncating mutation c.2761C>T; p.R921X detected by homozygosity mapping and sequencing in two infants affected by IAHSP with bulbar involvement. The mutation c.2761C>T resides in the pleckstrin domain, a characteristic segment of guanine nucleotide exchange factors of the Rho GTPase family, which is involved in the overall neuronal development or maintenance. This study highlights the importance of using homozygosity mapping combined with candidate gene analysis to identify the underlying genetic defect as in this Saudi consanguineous family.
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Affiliation(s)
- Salma M Wakil
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
| | - Khushnooda Ramzan
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Rula Abuthuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Samya Hagos
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Haya Al-Dossari
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Rana Al-Omar
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Hatem Murad
- Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Aziza Chedrawi
- Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Zuhair N Al-Hassnan
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | | | - Saeed Bohlega
- Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
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Abstract
The redox-inert transition metal Zn is a micronutrient that plays essential roles in protein structure, catalysis, and regulation of function. Inhalational exposure to ZnO or to soluble Zn salts in occupational and environmental settings leads to adverse health effects, the severity of which appears dependent on the flux of Zn(2+) presented to the airway and alveolar cells. The cellular toxicity of exogenous Zn(2+) exposure is characterized by cellular responses that include mitochondrial dysfunction, elevated production of reactive oxygen species, and loss of signaling quiescence leading to cell death and increased expression of adaptive and inflammatory genes. Central to the molecular effects of Zn(2+) are its interactions with cysteinyl thiols, which alters their functionality by modulating their reactivity and participation in redox reactions. Ongoing studies aimed at elucidating the molecular toxicology of Zn(2+) in the lung are contributing valuable information about its role in redox biology and cellular homeostasis in normal and pathophysiology.
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Affiliation(s)
- Weidong Wu
- School of Public Health XinXiang Medical University XinXiang, China 453003; Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Philip A Bromberg
- Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - James M Samet
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. EPA, Chapel Hill, NC 27514, USA.
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Philip B, Roland CL, Daniluk J, Liu Y, Chatterjee D, Gomez SB, Ji B, Huang H, Wang H, Fleming JB, Logsdon CD, Cruz-Monserrate Z. A high-fat diet activates oncogenic Kras and COX2 to induce development of pancreatic ductal adenocarcinoma in mice. Gastroenterology 2013; 145:1449-58. [PMID: 23958541 PMCID: PMC3873752 DOI: 10.1053/j.gastro.2013.08.018] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 08/07/2013] [Accepted: 08/12/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Obesity is a risk factor for pancreatic ductal adenocarcinoma (PDAC), but it is not clear how obesity contributes to pancreatic carcinogenesis. The oncogenic form of KRAS is expressed during early stages of PDAC development and is detected in almost all of these tumors. However, there is evidence that mutant KRAS requires an additional stimulus to activate its full oncogenic activity and that this stimulus involves the inflammatory response. We investigated whether the inflammation induced by a high-fat diet, and the accompanying up-regulation of cyclooxygenase-2 (COX2), increases Kras activity during pancreatic carcinogenesis in mice. METHODS We studied mice with acinar cell-specific expression of KrasG12D (LSL-Kras/Ela-CreERT mice) alone or crossed with COX2 conditional knockout mice (COXKO/LSL-Kras/Ela-CreERT). We also studied LSL-Kras/PDX1-Cre mice. All mice were fed isocaloric diets with different amounts of fat, and a COX2 inhibitor was administered to some LSL-Kras/Ela-CreERT mice. Pancreata were collected from mice and analyzed for Kras activity, levels of phosphorylated extracellular-regulated kinase, inflammation, fibrosis, pancreatic intraepithelial neoplasia (PanIN), and PDACs. RESULTS Pancreatic tissues from LSL-Kras/Ela-CreERT mice fed high-fat diets (HFDs) had increased Kras activity, fibrotic stroma, and numbers of PanINs and PDACs than LSL-Kras/Ela-CreERT mice fed control diets; the mice fed the HFDs also had shorter survival times than mice fed control diets. Administration of a COX2 inhibitor to LSL-Kras/Ela-CreERT mice prevented these effects of HFDs. We also observed a significant reduction in survival times of mice fed HFDs. COXKO/LSL-Kras/Ela-CreERT mice fed HFDs had no evidence for increased numbers of PanIN lesions, inflammation, or fibrosis, as opposed to the increases observed in LSL-Kras/Ela-CreERT mice fed HFDs. CONCLUSIONS In mice, an HFD can activate oncogenic Kras via COX2, leading to pancreatic inflammation and fibrosis and development of PanINs and PDAC. This mechanism might be involved in the association between risk for PDAC and HFDs.
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Affiliation(s)
- Bincy Philip
- Department of Cancer Biology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Christina L. Roland
- Department of Surgical Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Jaroslaw Daniluk
- Department of Gastroenterology and Internal Medicine, Medical University of Bialystok, Bialystok, Poland
| | - Yan Liu
- Department of Cancer Biology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Deyali Chatterjee
- Department of Surgical Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Sobeyda B. Gomez
- Department of Cancer Biology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Baoan Ji
- Mayo Clinic, Rochester, Minnesota
| | - Haojie Huang
- Department of Cancer Biology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Huamin Wang
- Department of Pathology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Jason B. Fleming
- Department of Surgical Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Craig D. Logsdon
- Department of Cancer Biology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA,Department of GI Medical Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Zobeida Cruz-Monserrate
- Department of Cancer Biology, University of Texas, M. D. Anderson Cancer Center, Houston, TX, USA
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Cavin S, Maric D, Diviani D. A-kinase anchoring protein-Lbc promotes pro-fibrotic signaling in cardiac fibroblasts. Biochim Biophys Acta 2013; 1843:335-45. [PMID: 24269843 DOI: 10.1016/j.bbamcr.2013.11.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/30/2013] [Accepted: 11/13/2013] [Indexed: 01/14/2023]
Abstract
In response to stress or injury the heart undergoes an adverse remodeling process associated with cardiomyocyte hypertrophy and fibrosis. Transformation of cardiac fibroblasts to myofibroblasts is a crucial event initiating the fibrotic process. Cardiac myofibroblasts invade the myocardium and secrete excess amounts of extracellular matrix proteins, which cause myocardial stiffening, cardiac dysfunctions and progression to heart failure. While several studies indicate that the small GTPase RhoA can promote profibrotic responses, the exchange factors that modulate its activity in cardiac fibroblasts are yet to be identified. In the present study, we show that AKAP-Lbc, an A-kinase anchoring protein (AKAP) with an intrinsic Rho-specific guanine nucleotide exchange factor (GEF) activity, is critical for activating RhoA and transducing profibrotic signals downstream of type I angiotensin II receptors (AT1Rs) in cardiac fibroblasts. In particular, our results indicate that suppression of AKAP-Lbc expression by infecting adult rat ventricular fibroblasts with lentiviruses encoding AKAP-Lbc specific short hairpin (sh) RNAs strongly reduces the ability of angiotensin II to promote RhoA activation, differentiation of cardiac fibroblasts to myofibroblasts, collagen deposition as well as myofibroblast migration. Interestingly, AT1Rs promote AKAP-Lbc activation via a pathway that requires the α subunit of the heterotrimeric G protein G12. These findings identify AKAP-Lbc as a key Rho-guanine nucleotide exchange factor modulating profibrotic responses in cardiac fibroblasts.
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Affiliation(s)
- Sabrina Cavin
- Department of Pharmacology and Toxicology, Faculté de Biologie et Médecine, University of Lausanne, 1005, Switzerland
| | - Darko Maric
- Department of Pharmacology and Toxicology, Faculté de Biologie et Médecine, University of Lausanne, 1005, Switzerland
| | - Dario Diviani
- Department of Pharmacology and Toxicology, Faculté de Biologie et Médecine, University of Lausanne, 1005, Switzerland.
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Xie N, Wang C, Lian Y, Wu C, Zhang H, Zhang Q. Inhibition of mitochondrial fission attenuates Aβ-induced microglia apoptosis. Neuroscience 2014; 256:36-42. [PMID: 24144623 DOI: 10.1016/j.neuroscience.2013.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 09/15/2013] [Accepted: 10/03/2013] [Indexed: 01/08/2023]
Abstract
Mitochondrial division inhibitor 1 (mdivi-1), a selective inhibitor of mitochondrial fission protein dynamin-related protein 1 (Drp1), has been reported to display neuroprotective properties in different animal models. In the present study, we investigated the protective effect of mdivi-1 on β-amyloid protein (Aβ)-induced cytotoxicity and its potential mechanisms in BV-2 and primary microglial cells. We found that mitochondrial fission was increased in Aβ treatment and inhibition of mitochondrial fission by mdivi-1 significantly reduced Aβ-induced expression of CD11b (a marker of microglial activation), viability loss and apoptotic rate increase in BV-2 and primary microglial cells. Moreover, we also found that mdivi-1 treatment markedly reversed mitochondrial membrane potential loss, cytochrome c (CytC) release and caspase-3 activation. Altogether, our data suggested that mdivi-1 exerts neuroprotective effects against Aβ-induced microglial apoptosis, and the underlying mechanism may be through inhibiting mitochondrial membrane potential loss, CytC release and suppression of the mitochondrial apoptosis pathway.
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113
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Yamamoto H, Fara AF, Dasgupta P, Kemper C. CD46: the 'multitasker' of complement proteins. Int J Biochem Cell Biol 2013; 45:2808-20. [PMID: 24120647 DOI: 10.1016/j.biocel.2013.09.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 09/23/2013] [Accepted: 09/30/2013] [Indexed: 12/12/2022]
Abstract
Complement is undeniably quintessential for innate immunity by detecting and eliminating infectious microorganisms. Recent work, however, highlights an equally profound impact of complement on the induction and regulation of a wide range of immune cells. In particular, the complement regulator CD46 emerges as a key sensor of immune activation and a vital modulator of adaptive immunity. In this review, we summarize the current knowledge of CD46-mediated signalling events and their functional consequences on immune-competent cells with a specific focus on those in CD4(+) T cells. We will also discuss the promises and challenges that potential therapeutic modulation of CD46 may hold and pose.
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Affiliation(s)
- Hidekazu Yamamoto
- Division of Transplant Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, Guy's Hospital, London SE1 9RT, UK; The Urology Centre, Guy's and St. Thomas' NHS Foundations Trust, London SE1 9RT, UK
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Ohsaki Y, Cheng J, Yamairi K, Pan X, Hussain MM, Fujimoto T. Inhibition of ADP-ribosylation suppresses aberrant accumulation of lipidated apolipoprotein B in the endoplasmic reticulum. FEBS Lett 2013; 587:3696-702. [PMID: 24100140 DOI: 10.1016/j.febslet.2013.09.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/17/2013] [Accepted: 09/17/2013] [Indexed: 11/19/2022]
Abstract
ApoB-crescent, an endoplasmic reticulum (ER)-lipid droplet amalgamation structure, is a useful marker to indicate aberrant lipidated apolipoprotein B accumulation in the hepatocyte ER. Blockade of the ER-to-Golgi transport by either vesicle transport inhibitors or dominant-negative Arf1 caused a significant increase in ApoB-crescents. However, a low concentration of Brefeldin A induced the same result without affecting protein secretion, suggesting ADP-ribosylation as an additional mechanism. ADP-ribosylation inhibitors not only suppressed the increase of ApoB-crescents, but also rapidly dissolved existing ApoB-crescents. These results implicate the involvement of ADP-ribosylation in the ApoB-crescent formation and maintenance process at the ER.
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Affiliation(s)
- Yuki Ohsaki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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115
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Kim YK, Kim JH, Yu YS, Ko HW, Kim JH. Localization of primary cilia in mouse retina. Acta Histochem 2013; 115:789-94. [PMID: 23608602 DOI: 10.1016/j.acthis.2013.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 12/22/2022]
Abstract
The primary cilia are considered as "cellular antennae" that sense and interchange information with the extracellular environment. Nearly all mammalian cells have a single primary cilium. In the retina, the outer segment of the photoreceptor is known to be a specialized form of primary cilium, but studies on cilia in other layers of the retina are scarce. In this study, we investigated the expression of primary cilia in the whole thickness of the mouse retina using immunofluorescence with three different ciliary markers: Arl13b, acetylated α-tubulin and adenylyl cyclase III. Our results show positive reactions in the photoreceptor layer, outer plexiform layer and ganglion cell layer, which might suggest the possible presence of primary cilia in these areas, but we could not directly prove the strand-like shape of cilia in those areas. In the outer plexiform layer, all three markers showed intense staining along the neuronal synapses, which suggests that the neuronal processes themselves might share the features of cilia.
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Petrov RR, Knight L, Chen SR, Wager-Miller J, McDaniel SW, Diaz F, Barth F, Pan HL, Mackie K, Cavasotto CN, Diaz P. Mastering tricyclic ring systems for desirable functional cannabinoid activity. Eur J Med Chem 2013; 69:881-907. [PMID: 24125850 DOI: 10.1016/j.ejmech.2013.09.038] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/16/2013] [Accepted: 09/19/2013] [Indexed: 11/23/2022]
Abstract
There is growing interest in using cannabinoid receptor 2 (CB2) agonists for the treatment of neuropathic pain and other indications. In continuation of our ongoing program aiming for the development of new small molecule cannabinoid ligands, we have synthesized a novel series of carbazole and γ-carboline derivatives. The affinities of the newly synthesized compounds were determined by a competitive radioligand displacement assay for human CB2 cannabinoid receptor and rat CB1 cannabinoid receptor. Functional activity and selectivity at human CB1 and CB2 receptors were characterized using receptor internalization and [(35)S]GTP-γ-S assays. The structure-activity relationship and optimization studies of the carbazole series have led to the discovery of a non-selective CB1 and CB2 agonist, compound 4. Our subsequent research efforts to increase CB2 selectivity of this lead compound have led to the discovery of CB2 selective compound 64, which robustly internalized CB2 receptors. Compound 64 had potent inhibitory effects on pain hypersensitivity in a rat model of neuropathic pain. Other potent and CB2 receptor-selective compounds, including compounds 63 and 68, and a selective CB1 agonist, compound 74 were also discovered. In addition, we identified the CB2 ligand 35 which failed to promote CB2 receptor internalization and inhibited compound CP55,940-induced CB2 internalization despite a high CB2 receptor affinity. The present study provides novel tricyclic series as a starting point for further investigations of CB2 pharmacology and pain treatment.
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Lall P, Horgan CP, Oda S, Franklin E, Sultana A, Hanscom SR, McCaffrey MW, Khan AR. Structural and functional analysis of FIP2 binding to the endosome-localised Rab25 GTPase. Biochim Biophys Acta 2013; 1834:2679-90. [PMID: 24056041 DOI: 10.1016/j.bbapap.2013.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 09/08/2013] [Accepted: 09/12/2013] [Indexed: 11/30/2022]
Abstract
Rab small GTPases are the master regulators of intracellular trafficking in eukaryotes. They mediate spatial and temporal recruitment of effector proteins to distinct cellular compartments through GTP-induced changes in their conformation. Despite numerous structural studies, the molecular basis for Rab/effector specificity and subsequent biological activity remains poorly understood. Rab25, also known as Rab11c, which is epithelial-specific, has been heavily implicated in ovarian cancer development and independently appears to act as a tumour suppressor in the context of a distinct subset of carcinomas. Here, we show that Rab25 associates with FIP2 and can recruit this effector protein to endosomal membranes. We report the crystal structure of Rab25 in complex with the C-terminal region of FIP2, which consists of a central dimeric FIP2 coiled-coil that mediates a heterotetrameric Rab25-(FIP2)2-Rab25 complex. Thermodynamic analyses show that, despite a relatively conserved interface, FIP2 binds to Rab25 with an approximate 3-fold weaker affinity than to Rab11a. Reduced affinity is mainly associated with lower enthalpic gains for Rab25:FIP2 complex formation, and can be attributed to subtle differences in the conformations of switch 1 and switch 2. These cellular, structural and thermodynamic studies provide insight into the Rab11/Rab25 subfamily of small GTPases that regulate endosomal trafficking pathways in eukaryotes.
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Affiliation(s)
- Patrick Lall
- School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland
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118
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Arshadi D, Nikbin B, Shakiba Y, Kiani A, Jamshidi AR, Boroushaki MT. Plasma level of neopterin as a marker of disease activity in treated rheumatoid arthritis patients: association with gender, disease activity and anti-CCP antibody. Int Immunopharmacol 2013; 17:763-7. [PMID: 24055018 DOI: 10.1016/j.intimp.2013.08.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/09/2013] [Accepted: 08/30/2013] [Indexed: 11/28/2022]
Abstract
Immune system activation is known to be involved in the progression of rheumatoid arthritis (RA). The pro-inflammatory cytokine interferon-γ in various cells, including monocytes, induces neopterin production. Plasma level of neopterin has been measured in many autoimmune diseases and can be used as a marker of cellular immunity activation. In this study we measured the plasma level of neopterin in 418 treated RA patients and 398 age and sex matched healthy people by high pressure liquid chromatography (HPLC) method. Disease activity score was calculated in all patients by DAS-CRP method. Plasma level of neopterin was compared between RA and control groups. We also determined the association between neopterin level with gender and disease activity score in RA patients. Significantly higher level of neopterin was observed in RA patients compared to healthy controls. Moreover, there was higher neopterin level in male RA patients versus female patients. Plasma neopterin level was increased in patients with active disease and also was correlated with disease activity parameters. There was a significant correlation of plasma level of neopterin with age in both RA and control group and also age of onset and disease duration in RA patients. Anti-CCP positive patients had higher level of neopterin in comparison to anti-CCP negative patients and there was a significant correlation between neopterin level and anti-CCP titer. Our results indicated that neopterin is a sensitive marker for assaying background inflammation and disease activity score in RA patients and may be used as a marker for evaluation of therapy efficacy.
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Affiliation(s)
- Delnia Arshadi
- Department of Pharmacology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; Pharmacological Research Center of Medicinal Plants, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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Aslam M, Sedding D, Koshty A, Santoso S, Schulz R, Hamm C, Gündüz D. Nucleoside triphosphates inhibit ADP, collagen, and epinephrine-induced platelet aggregation: role of P2Y₁ and P2Y₁₂ receptors. Thromb Res 2013; 132:548-57. [PMID: 24071464 DOI: 10.1016/j.thromres.2013.08.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 06/30/2013] [Accepted: 08/27/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND Platelets express two ADP receptors namely P2Y1 and P2Y12 that regulate ADP and other agonists-induced platelet aggregation. P2Y1 receptor activation causes platelet shape change while P2Y12 receptor activation induces platelet aggregation. Previously, anti-aggregatory effects of ATP on ADP-induced and pro-aggregatory effects on epinephrine-induced platelet aggregation have been reported. However, the effects of other nucleoside triphosphates on platelet aggregation have never been described. The aim of the present study was to characterise the effects of nucleoside triphosphates (ATP, UTP, GTP, and CTP) on agonist-induced platelet aggregation. METHODS The experiments were performed on platelet rich plasma freshly isolated from blood donated by healthy human volunteers. RESULTS All the nucleoside triphosphates tested inhibited ADP- and collagen-induced platelet aggregation in a concentration-dependent manner with a rank order of potency, 2MeSATP >ATP ≥ α,β,methyleneATP>UTP >>CTP ≥ GTP. The IC50 values against ADP (10 μM)-induced platelet aggregation were 0.039 ± 0.013, 18 ± 7, 25 ± 6, 32 ± 9, 360 ± 130, and 400 ± 160 μM, respectively. Low concentrations of ATP induced platelet shape change which was due to contaminating ADP. However, higher concentrations antagonised ADP and MRS2365-induced platelet shape change. The ATP analogue α,β,methyleneATP and CTP but not UTP and GTP also antagonised ADP-induced platelet shape change. Similarly, low ATP concentrations potentiated epinephrine-induced platelet aggregation that was abolished by P2Y1 antagonist MRS2500 suggesting P2Y1 receptor activation due to contaminating ADP. Higher ATP concentrations, α,β,methyleneATP, UTP, CTP, and GTP antagonised epinephrine-induced platelet aggregation. CONCLUSION Thus, the data demonstrate nucleoside triphosphates in general act as P2Y12 receptor antagonists and antagonise ADP-, collagen-, and epinephrine-induced platelet aggregation.
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Affiliation(s)
- Muhammad Aslam
- Department of Cardiology/Angiology, University Hospital Giessen, Giessen, Germany.
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Laffon B, Aguilera F, Ríos-Vázquez J, García-Lestón J, Fuchs D, Valdiglesias V, Pásaro E. Endocrine and immunological parameters in individuals involved in Prestige spill cleanup tasks seven years after the exposure. Environ Int 2013; 59:103-111. [PMID: 23792419 DOI: 10.1016/j.envint.2013.05.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/16/2013] [Accepted: 05/27/2013] [Indexed: 06/02/2023]
Abstract
In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coast of Spain, impacting more than 1000km of coastline. A general concern led to a huge mobilization of human and technical resources, and more than 300,000 people participated in cleanup activities, which lasted up to 10months. Some endocrine and immunological alterations were reported in Prestige oil exposed subjects for several months. Therefore, the objective of this study was to evaluate if these alterations are still present seven years after the exposure. Fifty-four individuals exposed for at least 2months were compared to 50 matched referents. Prolactin and cortisol plasma concentrations, percentages of lymphocyte subsets (CD3(+), CD4(+), CD8(+), CD19(+), and CD56(+)16(+)), plasma levels of circulating cytokines (interleukin (IL) 2, IL4, IL6, IL10, tumour necrosis factor α, and interferon γ), and serum concentrations of neopterin, tryptophan and kynurenine were determined in peripheral blood samples. Results showed significant differences in exposed individuals vs. referents only in cortisol (increase), kynurenine and %CD16(+)56(+) lymphocytes (both decrease). Time of exposure to the oil or using protective clothes did not influence the results, but effect of using protective mask was observed on neopterin, %CD8(+), CD4(+)/CD8(+) ratio and IL4. Surveillance of the exposed individuals for early detection of possible health problems related to the endocrine or immunological systems is recommended.
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Affiliation(s)
- Blanca Laffon
- Toxicology Unit, Department of Psychobiology, University of A Coruña, Edificio de Servicios Centrales de Investigación, Campus Elviña s/n, 15071-A Coruña, Spain.
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Choi BR, Bang S, Chen Y, Cheah JH, Kim SF. PKA modulates iron trafficking in the striatum via small GTPase, Rhes. Neuroscience 2013; 253:214-20. [PMID: 23999124 DOI: 10.1016/j.neuroscience.2013.08.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 08/20/2013] [Accepted: 08/22/2013] [Indexed: 11/18/2022]
Abstract
Ras homolog enriched in striatum (Rhes), is a highly conserved small guanosine-5'-triphosphate (GTP) binding protein belonging to the Ras superfamily. Rhes is involved in the dopamine receptor-mediated signaling and behavior though adenylyl cyclase. The striatum-specific GTPase share a close homology with Dexras1, which regulates iron trafficking in the neurons when activated though the post-translational modification called s-nitrosylation by nitric oxide (NO). We report that Rhes physiologically interacted with Peripheral benzodiazepine receptor-associated protein7 and participated in iron uptake via divalent metal transporter 1 similar to Dexras1. Interestingly, Rhes is not S-nitrosylated by NO-treatment, however phosphorylated by protein kinase A at the site of serine-239. Two Rhes mutants - the phosphomimetic form (serine 239 to aspartic acid) and constitutively active form (alanine 173 to valine) - displayed an increase in iron uptake compared to the wild-type Rhes. These findings suggest that Rhes may play a crucial role in striatal iron homeostasis.
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Affiliation(s)
- Bo-Ran Choi
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31 St. TRL Rm 2207, Philadelphia, PA 19104
| | - Sookhee Bang
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31 St. TRL Rm 2207, Philadelphia, PA 19104
| | - Yong Chen
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31 St. TRL Rm 2207, Philadelphia, PA 19104
| | - Jaime H Cheah
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31 St. TRL Rm 2207, Philadelphia, PA 19104
| | - Sangwon F Kim
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31 St. TRL Rm 2207, Philadelphia, PA 19104
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Wojcik EJ, Buckley RS, Richard J, Liu L, Huckaba TM, Kim S. Kinesin-5: cross-bridging mechanism to targeted clinical therapy. Gene 2013; 531:133-49. [PMID: 23954229 DOI: 10.1016/j.gene.2013.08.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/29/2013] [Accepted: 08/02/2013] [Indexed: 12/28/2022]
Abstract
Kinesin motor proteins comprise an ATPase superfamily that works hand in hand with microtubules in every eukaryote. The mitotic kinesins, by virtue of their potential therapeutic role in cancerous cells, have been a major focus of research for the past 28 years since the discovery of the canonical Kinesin-1 heavy chain. Perhaps the simplest player in mitotic spindle assembly, Kinesin-5 (also known as Kif11, Eg5, or kinesin spindle protein, KSP) is a plus-end-directed motor localized to interpolar spindle microtubules and to the spindle poles. Comprised of a homotetramer complex, its function primarily is to slide anti-parallel microtubules apart from one another. Based on multi-faceted analyses of this motor from numerous laboratories over the years, we have learned a great deal about the function of this motor at the atomic level for catalysis and as an integrated element of the cytoskeleton. These data have, in turn, informed the function of motile kinesins on the whole, as well as spearheaded integrative models of the mitotic apparatus in particular and regulation of the microtubule cytoskeleton in general. We review what is known about how this nanomotor works, its place inside the cytoskeleton of cells, and its small-molecule inhibitors that provide a toolbox for understanding motor function and for anticancer treatment in the clinic.
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Hickey CM, Groten CJ, Sham L, Carter CJ, Magoski NS. Voltage-gated Ca2+ influx and mitochondrial Ca2+ initiate secretion from Aplysia neuroendocrine cells. Neuroscience 2013; 250:755-72. [PMID: 23876326 DOI: 10.1016/j.neuroscience.2013.07.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 01/14/2023]
Abstract
Neuroendocrine secretion often requires prolonged voltage-gated Ca(2+) entry; however, the ability of Ca(2+) from intracellular stores, such as endoplasmic reticulum or mitochondria, to elicit secretion is less clear. We examined this using the bag cell neurons, which trigger ovulation in Aplysia by releasing egg-laying hormone (ELH) peptide. Secretion from cultured bag cell neurons was observed as an increase in plasma membrane capacitance following Ca(2+) influx evoked by a 5-Hz, 1-min train of depolarizing steps under voltage-clamp. The response was similar for step durations of ≥ 50 ms, but fell off sharply with shorter stimuli. The capacitance change was attenuated by replacing external Ca(2+) with Ba(2+), blocking Ca(2+) channels, buffering intracellular Ca(2+) with EGTA, disrupting synaptic protein recycling, or genetic knock-down of ELH. Regarding intracellular stores, liberating mitochondrial Ca(2+) with the protonophore, carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone (FCCP), brought about an EGTA-sensitive elevation of capacitance. Conversely, no change was observed to Ca(2+) released from the endoplasmic reticulum or acidic stores. Prior exposure to FCCP lessened the train-induced capacitance increase, suggesting overlap in the pool of releasable vesicles. Employing GTP-γ-S to interfere with endocytosis delayed recovery (presumed membrane retrieval) of the capacitance change following FCCP, but not the train. Finally, secretion was correlated with reproductive behavior, in that neurons isolated from animals engaged in egg-laying presented a greater train-induced capacitance elevation vs quiescent animals. The bag cell neuron capacitance increase is consistent with peptide secretion requiring high Ca(2+), either from influx or stores, and may reflect the all-or-none nature of reproduction.
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Guo C, Yi C, Peng Y, Wen Y, Lin D. Solution structure and backbone dynamics of human Raf-1 kinase inhibitor protein. Biochem Biophys Res Commun 2013; 438:129-32. [PMID: 23872143 DOI: 10.1016/j.bbrc.2013.07.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 11/20/2022]
Abstract
Human Raf-1 kinase inhibitor protein (hRKIP) is a small multi-functional protein of 187 residues. It contains a conserved pocket, which binds a wide range of ligands from various small molecules to distinct proteins. To provide a structural basis for the ligand diversity of RKIP, we herein determined the solution structure of hRKIP, and analyzed its structural dynamics. In solution, hRKIP mainly comprises two antiparallel β sheets, two α helices and two 3₁₀ helices. NMR dynamic analysis reveals that the overall structure of hRKIP is rigid, but its C-terminal helix which is close to the ligand-binding site is mobile. In addition, residues around the ligand-binding pocket exhibit significant conformational exchange on the μs-ms timescale. Conformational flexibility may allow the ligand-binding pocket and the C-terminal helix to adopt various conformations to interact with different substrates. This work may shed light on the underlying molecular mechanisms of how hRKIP recognizes and binds diverse substrate ligands.
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125
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Sodhi M, Mukesh M, Kishore A, Mishra BP, Kataria RS, Joshi BK. Novel polymorphisms in UTR and coding region of inducible heat shock protein 70.1 gene in tropically adapted Indian zebu cattle (Bos indicus) and riverine buffalo (Bubalus bubalis). Gene 2013; 527:606-15. [PMID: 23792016 DOI: 10.1016/j.gene.2013.05.078] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 05/23/2013] [Accepted: 05/29/2013] [Indexed: 11/18/2022]
Abstract
Due to evolutionary divergence, cattle (taurine, and indicine) and buffalo are speculated to have different responses to heat stress condition. Variation in candidate genes associated with a heat-shock response may provide an insight into the dissimilarity and suggest targets for intervention. The present work was undertaken to characterize one of the inducible heat shock protein genes promoter and coding regions in diverse breeds of Indian zebu cattle and buffaloes. The genomic DNA from a panel of 117 unrelated animals representing 14 diversified native cattle breeds and 6 buffalo breeds were utilized to determine the complete sequence and gene diversity of HSP70.1 gene. The coding region of HSP70.1 gene in Indian zebu cattle, Bos taurus and buffalo was similar in length (1,926 bp) encoding a HSP70 protein of 641 amino acids with a calculated molecular weight (Mw) of 70.26 kDa. However buffalo had a longer 5' and 3' untranslated region (UTR) of 204 and 293 nucleotides respectively, in comparison to Indian zebu cattle and Bos taurus wherein length of 5' and 3'-UTR was 172 and 286 nucleotides, respectively. The increased length of buffalo HSP70.1 gene compared to indicine and taurine gene was due to two insertions each in 5' and 3'-UTR. Comparative sequence analysis of cattle (taurine and indicine) and buffalo HSP70.1 gene revealed a total of 54 gene variations (50 SNPs and 4 INDELs) among the three species in the HSP70.1 gene. The minor allele frequencies of these nucleotide variations varied from 0.03 to 0.5 with an average of 0.26. Among the 14 B. indicus cattle breeds studied, a total of 19 polymorphic sites were identified: 4 in the 5'-UTR and 15 in the coding region (of these 2 were non-synonymous). Analysis among buffalo breeds revealed 15 SNPs throughout the gene: 6 at the 5' flanking region and 9 in the coding region. In bubaline 5'-UTR, 2 additional putative transcription factor binding sites (Elk-1 and C-Re1) were identified, other than three common sites (CP2, HSE and Pax-4) observed across all the analyzed animals. No polymorphism was found within the 3'-UTR of Indian cattle or buffalo as it was found to be monomorphic. The promoter sequences generated in 117 individuals showed a rich array of sequence elements known to be involved in transcription regulation. A total of 11 nucleotide changes were observed in the promoter sequence across the analyzed species, 3 of these changes were located within the potential transcription factor binding domains. We also identified 4 microsatellite markers within the buffalo HSP70.1 gene and 3 microsatellites within bovine HSP70.1. The present study identified several distinct changes across indicine, taurine and bubaline HSP70.1 genes that could further be evaluated as molecular markers for thermotolerance.
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Affiliation(s)
- M Sodhi
- National Bureau of Animal Genetic resources, Karnal 132001, India.
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Barral K, Sallamand C, Petzold C, Coutard B, Collet A, Thillier Y, Zimmermann J, Vasseur JJ, Canard B, Rohayem J, Debart F, Decroly E. Development of specific dengue virus 2'-O- and N7-methyltransferase assays for antiviral drug screening. Antiviral Res 2013; 99:292-300. [PMID: 23769894 DOI: 10.1016/j.antiviral.2013.06.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 05/31/2013] [Accepted: 06/03/2013] [Indexed: 12/16/2022]
Abstract
Dengue virus (DENV) protein NS5 carries two mRNA cap methyltransferase (MTase) activities involved in the synthesis of a cap structure, (7Me)GpppA(2'OMe)-RNA, at the 5'-end of the viral mRNA. The methylation of the cap guanine at its N7-position (N7-MTase, (7Me)GpppA-RNA) is essential for viral replication. The development of high throughput methods to identify specific inhibitors of N7-MTase is hampered by technical limitations in the large scale synthesis of long capped RNAs. In this work, we describe an efficient method to generate such capped RNA, GpppA(2'OMe)-RNA₇₄, by ligation of two RNA fragments. Then, we use GpppA(2'OMe)-RNA₇₄ as a substrate to assess DENV N7-MTase activity and to develop a robust and specific activity assay. We applied the same ligation procedure to generate (7Me)GpppA-RNA₇₄ in order to characterize the DENV 2'-O-MTase activity specifically on long capped RNA. We next compared the N7- and 2'-O-MTase inhibition effect of 18 molecules, previously proposed to affect MTase activities. These experiments allow the validation of a rapid and sensitive method easily adaptable for high-throughput inhibitor screening in anti-flaviviral drug development.
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Affiliation(s)
- K Barral
- AFMB, CNRS, Aix-Marseille Université, UMR 7257, Case 932, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France.
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Patching SG. Surface plasmon resonance spectroscopy for characterisation of membrane protein-ligand interactions and its potential for drug discovery. Biochim Biophys Acta 2014; 1838:43-55. [PMID: 23665295 DOI: 10.1016/j.bbamem.2013.04.028] [Citation(s) in RCA: 257] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/25/2013] [Accepted: 04/29/2013] [Indexed: 11/22/2022]
Abstract
Surface plasmon resonance (SPR) spectroscopy is a rapidly developing technique for the study of ligand binding interactions with membrane proteins, which are the major molecular targets for validated drugs and for current and foreseeable drug discovery. SPR is label-free and capable of measuring real-time quantitative binding affinities and kinetics for membrane proteins interacting with ligand molecules using relatively small quantities of materials and has potential to be medium-throughput. The conventional SPR technique requires one binding component to be immobilised on a sensor chip whilst the other binding component in solution is flowed over the sensor surface; a binding interaction is detected using an optical method that measures small changes in refractive index at the sensor surface. This review first describes the basic SPR experiment and the challenges that have to be considered for performing SPR experiments that measure membrane protein-ligand binding interactions, most importantly having the membrane protein in a lipid or detergent environment that retains its native structure and activity. It then describes a wide-range of membrane protein systems for which ligand binding interactions have been characterised using SPR, including the major drug targets G protein-coupled receptors, and how challenges have been overcome for achieving this. Finally it describes some recent advances in SPR-based technology and future potential of the technique to screen ligand binding in the discovery of drugs. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.
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128
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Sawa T, Ihara H, Ida T, Fujii S, Nishida M, Akaike T. Formation, signaling functions, and metabolisms of nitrated cyclic nucleotide. Nitric Oxide 2013; 34:10-8. [PMID: 23632125 DOI: 10.1016/j.niox.2013.04.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/16/2013] [Indexed: 01/07/2023]
Abstract
8-Nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) is a unique derivative of guanosine 3',5'-cyclic monophosphate (cGMP) formed in mammalian and plant cells in response to production of nitric oxide and reactive oxygen species. 8-Nitro-cGMP possesses signaling activity inherited from parental cGMP, including induction of vasorelaxation through activation of cGMP-dependent protein kinase. On the other hand, 8-nitro-cGMP mediates cellular signaling that is not observed for native cGMP, e.g., it behaves as an electrophile and reacts with protein sulfhydryls, which results in cGMP adduction to protein sulfhydryls (protein S-guanylation). Several proteins have been identified as targets for endogenous protein S-guanylation, including Kelch-like ECH-associated protein 1 (Keap1), H-Ras, and mitochondrial heat shock proteins. 8-Nitro-cGMP signaling via protein S-guanylation of those proteins may have evolved to convey adaptive cellular stress responses. 8-Nitro-cGMP may not undergo conventional cGMP metabolism because of its resistance to phosphodiesterases. Hydrogen sulfide has recently been identified as a potent regulator for metabolisms of electrophiles including 8-nitro-cGMP, through sulfhydration of electrophiles, e.g., leading to the formation of 8-SH-cGMP. Better understanding of the molecular basis for the formation, signaling functions, and metabolisms of 8-nitro-cGMP would be useful for the development of new diagnostic approaches and treatment of diseases related to oxidative stress and redox metabolisms.
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Key Words
- 15-deoxy-Δ(12,14)-prostaglandin J(2)
- 15d-PGJ(2)
- 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one
- 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide
- 4-hydroxy-2-nonenal
- 4H-8-bromo-1,2,4-oxadiazolo(3,4-d)benz(b)(1,4)oxazin-1-one
- 60-kDa heat-shock protein
- 8-Nitro-cGMP
- 8-bromo-cGMP
- 8-bromoguanosine 3′,5′-cyclic monophosphate
- 8-nitroguanosine 3′,5′-cyclic monophosphate
- ATP
- CBS
- CSE
- ELISA
- ETC
- Electrophile
- GSH
- GTP
- HNE
- HO-1
- HPLC-ECD
- HSP60
- Hydrogen sulfide
- IFN-γ
- IL-1β
- Keap1
- Kelch-like ECH-associated protein 1
- LC–MS/MS
- LPS
- MI
- MPO
- N(G)-nitro-l-arginine methyl ester
- N(ω)-monomethyl-l-arginine
- NADPH oxidase
- NADPH oxidase 2
- NOS
- NS 2028
- Nox
- Nox2
- Nrf2
- ODQ
- Oxidative stress
- PDEs
- PKG
- PTM
- Protein S-guanylation
- RAR
- RNOS
- ROS
- SOD
- TNFα
- adenosine 3′,5′-cyclic monophosphate
- adenosine 5′-triphosphate
- cAMP
- cGMP
- cGMP-dependent protein kinase
- cPTIO
- cystathionine β-synthase
- cystathionine γ-lyase
- eNOS
- electron transport chain
- endothelial NOS
- enzyme-linked immunosorbent assay
- glutathione
- guanosine 3′,5′-cyclic monophosphate
- guanosine 5′-triphosphate
- heme oxygenase-1
- high-performance liquid chromatography with electrochemical detector
- iNOS
- inducible NOS
- interferon-γ
- interleukin-1β
- l-NAME
- l-NMMA
- lipopolysaccharide
- liquid chromatography with tandem mass spectrometry
- mPTP
- mitochondrial permeability transition pore
- myeloperoxidase
- myocardial infarction
- nNOS
- neuronal NOS
- nitric oxide synthases
- nuclear factor erythroid 2-related factor 2
- pGC
- particulate-type guanylyl cyclase
- phosphodiesterases
- post-translational modification
- reactive nitrogen oxide species
- reactive oxygen species
- retinoic acid receptor
- sGC
- soluble-type guanylyl cyclase
- superoxide dismutase
- tumor necrosis factor α
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Affiliation(s)
- Tomohiro Sawa
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan; PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-001, Japan
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Simonetti A, Marzi S, Fabbretti A, Hazemann I, Jenner L, Urzhumtsev A, Gualerzi CO, Klaholz BP. Structure of the protein core of translation initiation factor 2 in apo, GTP-bound and GDP-bound forms. Acta Crystallogr D Biol Crystallogr 2013; 69:925-33. [PMID: 23695237 PMCID: PMC3663118 DOI: 10.1107/s0907444913006422] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/06/2013] [Indexed: 11/30/2022]
Abstract
The crystal structures of the eubacterial translation initiation factor 2 in apo form and with bound GDP and GTP reveal conformational changes upon nucleotide binding and hydrolysis, notably of the catalytically important histidine in the switch II region. Translation initiation factor 2 (IF2) is involved in the early steps of bacterial protein synthesis. It promotes the stabilization of the initiator tRNA on the 30S initiation complex (IC) and triggers GTP hydrolysis upon ribosomal subunit joining. While the structure of an archaeal homologue (a/eIF5B) is known, there are significant sequence and functional differences in eubacterial IF2, while the trimeric eukaryotic IF2 is completely unrelated. Here, the crystal structure of the apo IF2 protein core from Thermus thermophilus has been determined by MAD phasing and the structures of GTP and GDP complexes were also obtained. The IF2–GTP complex was trapped by soaking with GTP in the cryoprotectant. The structures revealed conformational changes of the protein upon nucleotide binding, in particular in the P-loop region, which extend to the functionally relevant switch II region. The latter carries a catalytically important and conserved histidine residue which is observed in different conformations in the GTP and GDP complexes. Overall, this work provides the first crystal structure of a eubacterial IF2 and suggests that activation of GTP hydrolysis may occur by a conformational repositioning of the histidine residue.
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Affiliation(s)
- Angelita Simonetti
- Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104/Institut National de la Santé de la Recherche Médicale (INSERM) U964/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
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130
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Harrison LM, Lahoste GJ. The role of Rhes, Ras homolog enriched in striatum, in neurodegenerative processes. Exp Cell Res 2013; 319:2310-5. [PMID: 23583659 DOI: 10.1016/j.yexcr.2013.03.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/15/2013] [Accepted: 03/22/2013] [Indexed: 10/26/2022]
Abstract
Rhes is a small GTPase whose expression is highly enriched in striatum. It shares homology with Ras proteins, but also contains a C-terminal extension, thus suggesting additional functions. Signaling by 7 transmembrane receptors through heterotrimeric G proteins is inhibited by Rhes. However, perhaps the most remarkable feature of this small GTPase described thus far is that it can account for the selective vulnerability of the striatum in Huntington's Disease (HD). HD is an autosomal dominant neurodegenerative disease caused by a poly-glutamine expansion in the protein huntingtin. Despite the presence of huntingtin throughout the brain and the rest of the body, the striatum is selectively degenerated. Recent work shows that Rhes acts as an E3 ligase for attachment of SUMO (small ubiquitin-like modifier). As this post-translational modification decreases the formation of huntingtin aggregates and promotes cell death, this property of Rhes offers an explanation for selective striatal vulnerability in HD. In addition, the sequestering of Rhes through its binding to mutant huntingtin may decrease the ability of Rhes to perform vital physiological functions in the neuron. Thus, as Rhes is an attractive candidate for HD therapy, a thorough understanding of its physiological functions will allow for specific targeting of its pathological functions.
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Affiliation(s)
- Laura M Harrison
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, LA 70112, USA.
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Hopff D, Wienkoop S, Lüthje S. The plasma membrane proteome of maize roots grown under low and high iron conditions. J Proteomics 2013; 91:605-18. [PMID: 23353019 DOI: 10.1016/j.jprot.2013.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 12/11/2012] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
Abstract
Iron (Fe) homeostasis is essential for life and has been intensively investigated for dicots, while our knowledge for species in the Poaceae is fragmentary. This study presents the first proteome analysis (LC-MS/MS) of plasma membranes isolated from roots of 18-day old maize (Zea mays L.). Plants were grown under low and high Fe conditions in hydroponic culture. In total, 227 proteins were identified in control plants, whereas 204 proteins were identified in Fe deficient plants and 251 proteins in plants grown under high Fe conditions. Proteins were sorted by functional classes, and most of the identified proteins were classified as signaling proteins. A significant number of PM-bound redox proteins could be identified including quinone reductases, heme and copper-containing proteins. Most of these components were constitutive, and others could hint at an involvement of redox signaling and redox homeostasis by change in abundance. Energy metabolism and translation seem to be crucial in Fe homeostasis. The response to Fe deficiency includes proteins involved in development, whereas membrane remodeling and assembly and/or repair of Fe-S clusters is discussed for Fe toxicity. The general stress response appears to involve proteins related to oxidative stress, growth regulation, an increased rigidity and synthesis of cell walls and adaption of nutrient uptake and/or translocation. This article is part of a Special Issue entitled: Plant Proteomics in Europe.
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Affiliation(s)
- David Hopff
- University of Hamburg, Biocenter Klein Flottbek and Botanical Garden, Plant Physiology, Ohnhorststraße 18, D-22609 Hamburg, Germany
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