Science 15 March 2013 vol 339 issue 6125

[Science] 15 March 2013 vol 339, issue 6125, pages 1245 -1348 Perspectives-Environmental Science EW Cracking the Mercury Methylation Code Alexandre J. Poulain and Tamar Barkay Science 15 March 2013: 1280 -1281. [DOI: 10. 1126/science. 1235591] Identification of two genes involved in mercury methylation may help to develop biomarkers to track and manage mercury contamination in the environment. Science. 2013 Mar 15; 339(6125): 1332 -1335. Epub 2013 Feb 7. The Genetic Basis for Bacterial Mercury Methylation. Parks JM, Johs A, Podar M, Bridou R, Hurt RA Jr, Smith SD, Tomanicek SJ, Qian Y, Brown SD, Brandt CC, Palumbo AV, Smith JC, Wall JD, Elias DA, Liang L. Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Methylmercury is a potent neurotoxin produced in natural environments from inorganic mercury by anaerobic bacteria. However, until now the genes and proteins involved have remained unidentified. Here, we report a two-gene cluster, hgc. A and hgc. B, required for mercury methylationby Desulfovibrio desulfuricans ND 132 and Geobacter sulfurreducens PCA. In either bacterium, deletion of hgc. A, hgc. B, or both genes abolishesmercury methylation. The genes encode a putative corrinoid protein, Hgc. A, and a 2[4 Fe-4 S] ferredoxin, Hgc. B, consistent with roles as a methyl carrier and an electron donor required for corrinoid cofactor reduction, respectively. Among bacteria and archaea with sequenced genomes, gene orthologs are present in confirmed methylators but absent in nonmethylators, suggesting a common mercury methylation pathway in all methylating bacteria and archaea sequenced to date.

[Science] 15 March 2013 vol 339, issue 6125, pages 1245 -1348 Perspectives-Neuroscience The Brain Activity Map A. Paul Alivisatos, Miyoung Chun, George M. Church, Karl Deisseroth, John P. Donoghue, Ralph J. Greenspan, Paul L. Mc. Euen, Michael L. Roukes, Terrence J. Sejnowski, Paul S. Weiss, and Rafael Yuste Science 15 March 2013: 1284 -1285. Researchers propose building technologies to enable comprehensive mapping of neural circuit activity to understand brain function and disease. Epidemiology The SARS Wake-Up Call Isabelle Nuttall and Christopher Dye Science 15 March 2013: 1287 -1288. [DOI: 10. 1126/science. 1236434] Ten years ago, the SARS outbreak spurred efforts by the World Health Organization to improve global responses to health threats and crises. Biochemistry How HIF-1α Handles Stress L. Eric Huang Science 15 March 2013: 1285 -1286. [DOI: 10. 1126/science. 1236966] A transcription factor responds to low oxygen by controlling gene expression, DNA replication, and cell division to promote survival. A Nontranscriptional Role for HIF-1α as a Direct Inhibitor of DNA Replication Maimon E. Hubbi, Kshitiz, Daniele M. Gilkes, Sergio Rey, Carmen C. Wong, Weibo Luo, Deok-Ho Kim, Chi V. Dang, Andre Levchenko, and Gregg L. Semenza 12 February 2013: ra 10. In response to hypoxia, HIF-1α induces cell cycle arrest by inhibiting a helicase complex that unwinds DNA in preparation for replication.

[Science] 15 March 2013 vol 339, issue 6125, pages 1245 -1348 Perspectives Neuroscience RNA That Gets RAN in Neurodegeneration J. Paul Taylor Science 15 March 2013: 1282 -1283. [DOI: 10. 1126/science. 1236450] A common neurodegenerative disease is associated with unconventional translation of mutant expanded RNA. [ Science. 2013 Mar 15; 339(6125): 1335 -1338. Epub 2013 Feb 7. The C 9 orf 72 GGGGCC Repeat Is Translated into Aggregating Dipeptide-Repeat Proteins in FTLD/ALS. Mori K, Weng SM, Arzberger T, May S, Rentzsch K, Kremmer E, Schmid B, Kretzschmar HA, Cruts M, Van Broeckhoven C, Haass C, Edbauer D. Adolf Butenandt-Institute, Biochemistry, Ludwig-Maximilians University (LMU) Munich, Schillerstrasse 44, 80336 Munich, Germany. Expansion of a GGGGCC hexanucleotide repeat upstream of the C 9 orf 72 coding region is the most common cause of familial frontotemporal lobar degeneration and amyotrophic lateral sclerosis (FTLD/ALS), but the pathomechanisms involved are unknown. As in other FTLD/ALSvariants, characteristic intracellular inclusions of misfolded proteins define C 9 orf 72 pathology, but the core proteins of the majority of inclusions are still unknown. Here, we found that most of these characteristic inclusions contain poly-(Gly-Ala) and, to a lesser extent, poly-(Gly-Pro) and poly-(Gly-Arg) dipeptiderepeat proteins presumably generated by non-ATG-initiated translation from the expanded GGGGCC repeat in three reading frames. These findings directly link the FTLD/ALS-associated genetic mutation to the predominant pathology in patients with C 9 orf 72 hexanucleotide expansion.

[Science] 15 March 2013 vol 339, issue 6125, pages 1245 -1348 Science. 2013 Mar 15; 339(6125): 1320 -1323. Epub 2013 Feb 21. Quantitative Phosphoproteomics Reveal m. TORC 1 Activates de Novo Pyrimidine Synthesis. Robitaille AM, Christen S, Shimobayashi M, Cornu M, Fava LL, Moes S, Prescianotto-Baschong C, Sauer U, Jenoe P, Hall MN. Biozentrum, University of Basel, 4056 Basel, Switzerland. The Ser-Thr kinase mammalian target of rapamycin (m. TOR) controls cell growth and metabolism by stimulating glycolysis and synthesis of proteins and lipids. To further understand the central role of m. TOR in cell physiology, we used quantitative phosphoproteomics to identify substrates or downstream effectors of the two m. TOR complexes. m. TOR controlled the phosphorylation of 335 proteins, including CAD (carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase). CAD catalyzes the first three steps in de novopyrimidine synthesis. m. TORC 1 indirectly phosphorylated CAD-S 1859 through S 6 kinase (S 6 K). CAD-S 1859 phosphorylation promoted CAD oligomerization and thereby stimulated de novo synthesis of pyrimidines and progression through S phase of the cell cycle in mammalian cells. Thus, m. TORC 1 also stimulates the synthesis of nucleotides to control cell proliferation. Science. 2013 Mar 15; 339(6125): 1323 -1328. Epub 2013 Feb 21. Stimulation of de Novo Pyrimidine Synthesis by Growth Signaling Through m. TOR and S 6 K 1. Ben-Sahra I, Howell JJ, Asara JM, Manning BD. Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA. Cellular growth signals stimulate anabolic processes. The mechanistic target of rapamycin complex 1 (m. TORC 1) is a protein kinase that sensesgrowth signals to regulate anabolic growth and proliferation. Activation of m. TORC 1 led to the acute stimulation of metabolic flux through the denovo pyrimidine synthesis pathway. m. TORC 1 signaling posttranslationally regulated this metabolic pathway via its downstream target ribosomal protein S 6 kinase 1 (S 6 K 1), which directly phosphorylates S 1859 on CAD (carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, dihydroorotase), the enzyme that catalyzes the first three steps of de novo pyrimidine synthesis. Growth signaling through m. TORC 1 thus stimulates the production of new nucleotides to accommodate an increase in RNA and DNA synthesis needed for ribosome biogenesis and anabolic growth.

[Science] 15 March 2013 vol 339, issue 6125, pages 1245 -1348 Science. 2013 Mar 15; 339(6125): 1328 -1331. Epub 2013 Jan 31. Proteomic Mapping of Mitochondria in Living Cells via Spatially Restricted Enzymatic Ta gging. Rhee HW, Zou P, Udeshi ND, Martell JD, Mootha VK, Carr SA, Ting AY. Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Microscopy and mass spectrometry (MS) are complementary techniques: The former provides spatiotemporal information in living cells, but only for a handful of recombinant proteins at a time, whereas the latter can detect thousands of endogenous proteins simultaneously, but only in lysed samples. Here, we introduce technology that combines these strengths by offering spatially and temporally resolved proteomic maps of endogenous proteins within living cells. Our method relies on a genetically targetable peroxidase enzyme that biotinylates nearby proteins, which are subsequently purified and identified by MS. We used this approach to identify 495 proteins within the human mitochondrial matrix, including 31 not previously linked to mitochondria. The labeling was exceptionally specific and distinguished between inner membrane proteins facing the matrix versus the intermembrane space (IMS). Several proteins previously thought to reside in the IMS or outer membrane, including protoporphyrinogen oxidase, were reassigned to the matrix by our proteomic data and confirmed by electron microscopy. The specificity of peroxidase-mediated proteomic mapping in live cells, combined with its ease of use, offers biologists a powerful tool for understanding the molecular composition of living cells.

[Science Sig] 12 March 2013 Vol 6, Issue 266

KJ Sustained Interleukin-1β Overexpression Exacerbates Tau Pathology Despite Reduced Amyloid Burden in an Alzheimer's Mouse Model Simantini Ghosh, Michael D. Wu, Solomon S. Shaftel, Stephanos Kyrkanides, Frank M. La. Ferla, John A. Olschowka, and M. Kerry O'Banion Abstract Neuroinflammation is an important component of Alzheimer's disease (AD) pathogenesis and has been implicated in neurodegeneration. Interleukin-1 (IL-1), a potent inflammatory cytokine in the CNS, is chronically upregulated in human AD and believed to serve as part of a vicious inflammatory cycle that drives AD pathology. To further understand the role of IL-1β in AD pathogenesis, we used an inducible model of sustained IL-1β overexpression (IL 1βXAT) developed in our laboratory. The triple transgenic mouse model of AD, which develops plaques and tangles later in its life cycle, was bred with IL-1βXAT mice, and effects of IL-1β overexpression on AD pathology were assessed in F 1 progeny. After 1 and 3 months of transgene expression, we found robust increases in tau phosphorylation despite an ∼ 70– 80% reduction in amyloid load and fourfold to sixfold increase in plaque-associated microglia, as well as evidence of greater microglial activation at the site of inflammation. We also found evidence of increased p 38 mitogen-activated protein kinase and glycogen synthase kinase-3β activity, which are believed to contribute to tau phosphorylation. Thus, neuroinflammation regulates amyloid and tau pathology in opposing ways, suggesting that it provides a link between amyloid accumulation and changes in tau and raising concerns about the use of immunomodulatory therapies in AD.

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MH Research Article Fibroblast Growth Factor 2 Induces E-Cadherin Down-Regulation via PI 3 K/Akt/m. TOR and MAPK/ERK Signaling in Ovarian Cancer Cells Affiliation: Department of Obstetrics and Gynecology, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada Abstract Fibroblast growth factor 2 (FGF 2) is produced by ovarian cancer cells and it has been suggested to play an important role in tumor progression. In this study, we report that FGF 2 treatment down-regulated E-cadherin by up-regulating its transcriptional repressors, Slug and ZEB 1, in human ovarian cancer cells. The pharmacological inhibition of phosphatidylinositol-3 -kinase (PI 3 K), mammalian target of rapamycin (m. TOR), and MEK suggests that both PI 3 K/Akt/m. TOR and MAPK/ERK signaling are required for FGF 2 -induced E-cadherin down-regulation. Moreover, FGF 2 up-regulated Slug and ZEB 1 expression via the PI 3 K/Akt/m. TOR and MAPK/ERK signaling pathways, respectively. Finally, FGF 2 -induced cell invasion was abolished by the inhibition of the PI 3 K/Akt/m. TOR and MAPK/ERK pathways, and the forced expression of E-cadherin diminished the intrinsic invasiveness of ovarian cancer cells as well as the FGF 2 -induced cell invasion. This study demonstrates a novel mechanism in which FGF 2 down-regulates E-cadherin expression through the activation of PI 3 K/Akt/m. TOR and MAPK/ERK signaling, and the up-regulation of Slug and ZEB 1 in human ovarian cancer cells.

Research Article Insulin-Stimulated Degradation of Apolipoprotein B 100: Roles of Class II Phosphatidylinositol-3 -Kinase and Autophagy Affiliation: Department of Medicine (Cardiology) and the Marc and Ruti Bell Program in Vascular Biology; and the Department of Cell Biology, New York University School of Medicine, New York, United States of America Abstract Both in humans and animal models, an acute increase in plasma insulin levels, typically following meals, leads to transient depression of hepatic secretion of very low density lipoproteins (VLDL). One contributing mechanism for the decrease in VLDL secretion is enhanced degradation of apolipoprotein B 100 (apo. B 100), which is required for VLDL formation. Unlike the degradation of nascent apo. B 100, which occurs in the endoplasmic reticulum (ER), insulinstimulated apo. B 100 degradation occurs post-ER and is inhibited by pan-phosphatidylinositol (PI)3 -kinase inhibitors. It is unclear, however, which of the three classes of PI 3 -kinases is required for insulin-stimulated apo. B 100 degradation, as well as the proteolytic machinery underlying this response. Class III PI 3 -kinase is not activated by insulin, but the other two classes are. By using a class I-specific inhibitor and si. RNA to the major class II isoform in liver, we now show that it is class II PI 3 -kinase that is required for insulin-stimulated apo. B 100 degradation in primary mouse hepatocytes. Because the insulin-stimulated process resembles other examples of apo. B 100 post-ER proteolysis mediated by autophagy, we hypothesized that the effects of insulin in autophagy-deficient mouse primary hepatocytes would be attenuated. Indeed, apo. B 100 degradation in response to insulin was significantly impaired in two types of autophagy-deficient hepatocytes. Together, our data demonstrate that insulin-stimulated apo. B 100 degradation in the liver requires both class II PI 3 -kinase activity and autophagy.

Rab GTPases Regulate Endothelial Cell Protein C Receptor-Mediated Endocytosis and Trafficking of Factor VIIa Ramesh C. Nayak, Shiva Keshava, Charles T. Esmon, Usha R. Pendurthi, L. Vijaya Mohan Rao Research Article | published 15 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0059304 Views: 74 • Citations: None • Bookmarks: None Fibroblast Growth Factor 2 Induces E-Cadherin Down-Regulation via PI 3 K/Akt/m. TOR and MAPK/ERK Signaling in Ovarian Cancer Cells Man-Tat Lau, Wai-Kin So, Peter C. K. Leung Research Article | published 15 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0059083 Views: 82 • Citations: None • Bookmarks: None Breast Cancer and Obesity: In Vitro Interferences between Adipokines and Proangiogenic Features and/or Antitumor Therapies? Virginie Dubois, Laetitia Delort, Hermine Billard, Marie. Paule Vasson, Florence Caldefie-Chezet Research Article | published 15 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0058541 Views: 60 • Citations: None • Bookmarks: None Association of Single Nucleotide Polymorphisms in Wnt Signaling Pathway Genes with Breast Cancer in Saudi Patients Mohammad Saud Alanazi, Narasimha Reddy Parine, Jilani Purusottapatnam Shaik, Huda A. Alabdulkarim, Sana Abdulla Ajaj, Zahid Khan Research Article | published 14 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0059555 Views: 254 • Citations: None • Bookmarks: None Therapeutic Efficacy of C-Kit-Targeted Radioimmunotherapy Using 90 Y-Labeled Anti-C-Kit Antibodies in a Mouse Model of Small Cell Lung Cancer Chisato Yoshida, Atsushi B. Tsuji, Hitomi Sudo, Aya Sugyo, Tatsuya Kikuchi, Mitsuru Koizumi, Yasushi Arano, Tsuneo Saga Research Article | published 14 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0059248 Views: 22 • Citations: None • Bookmarks: None Structural Insights into the Mechanism of Phosphoregulation of the Retinoblastoma Protein Ekaterina P. Lamber, Fabienne Beuron, Edward P. Morris, Dmitri I. Svergun, Sibylle Mittnacht Research Article | published 14 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0058463 Views: 33 • Citations: None • Bookmarks: None Inhibition of Rho and Rac Geranylgeranylation by Atorvastatin Is Critical for Preservation of Endothelial Junction Integrity Hongbing Xiao, Xiong Qin, Ding Ping, Keqiang Zuo Research Article | published 13 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0059233 Views: 131 • Citations: None • Bookmarks: None P 38/NF-κB/Snail Pathway Is Involved in Caffeic Acid-Induced Inhibition of Cancer Stem Cells-Like Properties and Migratory Capacity in Malignant Human Keratinocyte Ye Yang, Yuan Li, Kebo Wang, Yu Wang, Wenqin Yin, Lei Li Research Article | published 13 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0058915 Views: 69 • Citations: None • Bookmarks: None Effect of G-Quadruplex Polymorphism on the Recognition of Telomeric DNA by a Metal Complex Caterina Musetti, A. Paul Krapcho, Manlio Palumbo, Claudia Sissi Research Article | published 13 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0058529 Views: 181 • Citations: None • Bookmarks: None Culturing on Wharton's Jelly Extract Delays Mesenchymal Stem Cell Senescence through p 53 and p 16 INK 4 a/p. Rb Pathways Haojie Hao, Guanghui Chen, Jiejie Liu, Dongdong Ti, Yali Zhao, Shenjun Xu, Xiaobing Fu, Weidong Han Research Article | published 13 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0058314 Views: 24 • Citations: None • Bookmarks: None Insulin-Stimulated Degradation of Apolipoprotein B 100: Roles of Class II Phosphatidylinositol-3 -Kinase and Autophagy Ursula Andreo, Liang Guo, Doru V. Chirieac, Ana C. Tuyama, Emilie Montenont, Jeffrey L. Brodsky, Edward A. Fisher Research Article | published 13 Mar 2013 | PLOS ONE 10. 1371/journal. pone. 0057590