Author
Gilles A. Lajoie
Other affiliations: University of Waterloo, McGill University, University of Guelph ...read more
Bio: Gilles A. Lajoie is an academic researcher from University of Western Ontario. The author has contributed to research in topics: Amino acid & Mass spectrometry. The author has an hindex of 45, co-authored 176 publications receiving 9305 citations. Previous affiliations of Gilles A. Lajoie include University of Waterloo & McGill University.
Papers published on a yearly basis
Papers
More filters
TL;DR: A new de novo sequencing software package, PEAKS, is described, to extract amino acid sequence information without the use of databases, using a new model and a new algorithm to efficiently compute the best peptide sequences whose fragment ions can best interpret the peaks in the MS/MS spectrum.
Abstract: A number of different approaches have been described to identify proteins from tandem mass spectrometry (MS/MS) data. The most common approaches rely on the available databases to match experimental MS/MS data. These methods suffer from several drawbacks and cannot be used for the identification of proteins from unknown genomes. In this communication, we describe a new de novo sequencing software package, PEAKS, to extract amino acid sequence information without the use of databases. PEAKS uses a new model and a new algorithm to efficiently compute the best peptide sequences whose fragment ions can best interpret the peaks in the MS/MS spectrum. The output of the software gives amino acid sequences with confidence scores for the entire sequences, as well as an additional novel positional scoring scheme for portions of the sequences. The performance of PEAKS is compared with Lutefisk, a well-known de novo sequencing software, using quadrupole-time-of-flight (Q-TOF) data obtained for several tryptic peptides from standard proteins.
1,239 citations
TL;DR: The ability to identify the low mass and abundance components of Matrigel illustrates the utility of this method for the analysis of the extracellular matrix, as well as the complexity of the matrix itself.
Abstract: Numerous cell types require a surface for attachment to grow and proliferate. Certain cells, particularly primary and stem cells, necessitate the use of specialized growth matrices along with specific culture media conditions to maintain the cells in an undifferentiated state. A gelatinous protein mixture derived from mouse tumor cells and commercialized as Matrigel is commonly used as a basement membrane matrix for stem cells because it retains the stem cells in an undifferentiated state. However, Matrigel is not a well-defined matrix, and therefore can produce a source of variability in experimental results. In this study, we present an in-depth proteomic analysis of Matrigel using a dynamic iterative exclusion method coupled with fractionation protocols that involve ammonium sulfate precipitation, size exclusion chromatography, and one-dimensional SDS-PAGE. The ability to identify the low mass and abundance components of Matrigel illustrates the utility of this method for the analysis of the extracellular matrix, as well as the complexity of the matrix itself.
1,174 citations
TL;DR: A new database search tool, PEAKS DB, has been developed by incorporating the de novo sequencing results into the database search, and achieves significantly improved accuracy and sensitivity over two other commonly used software packages.
815 citations
TL;DR: This study demonstrates a direct role of the IGF-II/IGF1R axis on human ES cell physiology and establishes that hdFs produced by human ES cells themselves define the stem cell niche of pluripotent human stem cells.
Abstract: Distinctive properties of stem cells are not autonomously achieved, and recent evidence points to a level of external control from the microenvironment. Here, we demonstrate that self-renewal and pluripotent properties of human embryonic stem (ES) cells depend on a dynamic interplay between human ES cells and autologously derived human ES cell fibroblast-like cells (hdFs). Human ES cells and hdFs are uniquely defined by insulin-like growth factor (IGF)- and fibroblast growth factor (FGF)-dependence. IGF 1 receptor (IGF1R) expression was exclusive to the human ES cells, whereas FGF receptor 1 (FGFR1) expression was restricted to surrounding hdFs. Blocking the IGF-II/IGF1R pathway reduced survival and clonogenicity of human ES cells, whereas inhibition of the FGF pathway indirectly caused differentiation. IGF-II is expressed by hdFs in response to FGF, and alone was sufficient in maintaining human ES cell cultures. Our study demonstrates a direct role of the IGF-II/IGF1R axis on human ES cell physiology and establishes that hdFs produced by human ES cells themselves define the stem cell niche of pluripotent human stem cells.
636 citations
McGill University1, Institute for Systems Biology2, University of British Columbia3, National Institutes of Health4, Invitrogen5, Allergan6, Northeastern University7, Ruhr University Bochum8, Massachusetts Institute of Technology9, Discovery Institute10, Fred Hutchinson Cancer Research Center11, Georgetown University12, University of Gothenburg13, Harvard University14, Thermo Fisher Scientific15, Laval University16, Walter and Eliza Hall Institute of Medical Research17, University of Toronto18, Scripps Research Institute19, University of Alberta20, University of California, Los Angeles21, University College Dublin22, University of Michigan23, University of Pittsburgh24, University of Victoria25, University of Western Ontario26, Wistar Institute27, Yamaguchi University28, Yonsei University29, Agilent Technologies30, Applied Biosystems31, Waters Corporation32
TL;DR: Central analysis determined missed identifications, environmental contamination, database matching and curation of protein identifications as sources of problems in liquid chromatography–mass spectrometry–based proteomics.
Abstract: We performed a test sample study to try to identify errors leading to irreproducibility, including incompleteness of peptide sampling, in liquid chromatography-mass spectrometry-based proteomics. We distributed an equimolar test sample, comprising 20 highly purified recombinant human proteins, to 27 laboratories. Each protein contained one or more unique tryptic peptides of 1,250 Da to test for ion selection and sampling in the mass spectrometer. Of the 27 labs, members of only 7 labs initially reported all 20 proteins correctly, and members of only 1 lab reported all tryptic peptides of 1,250 Da. Centralized analysis of the raw data, however, revealed that all 20 proteins and most of the 1,250 Da peptides had been detected in all 27 labs. Our centralized analysis determined missed identifications (false negatives), environmental contamination, database matching and curation of protein identifications as sources of problems. Improved search engines and databases are needed for mass spectrometry-based proteomics.
324 citations
Cited by
More filters
28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
TL;DR: Let-7 regulates multiple BT-IC stem cell-like properties by silencing more than one target, and miRNA expression in self-renewing and differentiated cells from breast cancer lines and in breast T-IC and non-BT-IC from 1 degrees breast cancers is compared.
1,909 citations
01 Jan 2005
TL;DR: Extraction and Solubilization of Proteins for Proteomic Studies Richard M. Leimgruber Preparation of Bacterial Samples for 2-D PAGE Brian Berg Vandahl, Gunna Christiansen, and Svend Birkelund Preparations of Yeast SamplesFor 2- D PAGE Joakim Norbeck Preparation for Mammalian Tissue Samples For Two-Dimensional Electrophoresis
Abstract: Extraction and Solubilization of Proteins for Proteomic Studies Richard M. Leimgruber Preparation of Bacterial Samples for 2-D PAGE Brian Berg Vandahl, Gunna Christiansen, and Svend Birkelund Preparation of Yeast Samples for 2-D PAGE Joakim Norbeck Preparation of Mammalian Tissue Samples for Two-Dimensional Electrophoresis Frank A. Witzmann Differential Detergent Fractionation of Eukaryotic Cells Melinda L. Ramsby and Gregory S. Makowski Serum or Plasma Sample Preparation for Two-Dimensional Gel Electrophoresis Anthony G. Sullivan, Stephen Russell, Henry Brzeski, Richard I. Somiari, and Craig D. Shriver Preparation of Plant Protein Samples for 2-D PAGE David W. M. Leung Laser-Assisted Microdissection in Proteomic Analyses Darrell L. Ellsworth, Stephen Russell, Brenda Deyarmin, Anthony G. Sullivan, Henry Brzeski, Richard I. Somiari, and Craig D. Shriver Purification of Cellular and Organelle Populations by Fluorescence-Activated Cell Sorting for Proteome Analysis William L. Godfrey, Colette J. Rudd, Sujata Iyer, and Diether Recktenwald Purification of Nucleoli From Lymphoma Cells and Solubilization of Nucleolar Proteins for 2-DE Separation Regis Dieckmann, Yohann Coute, Denis Hochstrasser, Jean-Jacques Diaz, and Jean-Charles Sanchez Prefractionation of Complex Protein Mixture for 2-D PAGE Using Reversed-Phase Liquid Chromatography Volker Badock and Albrecht Otto Fractionation of Complex Proteomes by Microscale Solution Isoelectrofocusing Using ZOOM(TM) IEF Fractionators to Improve Protein Profiling Xun Zuo, Ki-Boom Lee, and David W. Speicher Large-Format 2-D Polyacrylamide Gel Electrophoresis Henry Brzeski, Stephen Russell, Anthony G. Sullivan, Richard I. Somiari, and Craig D. Shiver Analysis of Membrane Proteins by Two-Dimensional Gels MichaelFountoulakis 2-D PAGE of High-Molecular-Mass Proteins Masamichi Oh-Ishi and Tadakazu Maeda Using Ultra-Zoom Gels for High-Resolution Two-Dimensional Polyacrylamide Gel Electrophoresis Sjouke Hoving, Hans Voshol, and Jan van Oostrum NEpHGE and pI Strip Proteomic 2-D Gel Electrophoretic Mapping of Lipid-Rich Membranes Steven E. Pfeiffer, Yoshihide Yamaguchi, Cecilia B. Marta, Rashmi Bansal, and Christopher M. Taylor Silver Staining of 2-D Gels Julia Poland, Thierry Rabilloud, and Pranav Sinha Zn2+ Reverse Staining Technique Carlos Fernandez-Patron Multiplexed Proteomics Technology for the Fluorescence Detection of Glycoprotein Levels and Protein Expression Levels Using Pro-Q(R) Emerald and SYPRO(R) Ruby Dyes Birte Schulenberg and Wayne F. Patton Multiplexed Proteomics Technology for the Fluorescence Detection of Phosphorylation and Protein Expression Levels Using Pro-Q(R) Diamond and SYPRO(R) Ruby Dyes Birte Schulenberg, Terrie Goodman, Thomas H. Steinberg, and Wayne F. Patton Sensitive Quantitative Fluorescence Detection of Proteins in Gels Using SYPRO(R) Ruby Protein Gel Stain Birte Schulenberg, Nancy Ahnert, and Wayne F. Patton Rapid, Sensitive Detection of Proteins in Minigels With Fluorescent Dyes: Coomassie Fluor Orange, SYPRO(R) Orange, SYPRO Red, and SYPRO Tangerine Protein Gel Stains Thomas H. Steinberg, Courtenay R. Hart, and Wayne F. Patton Differential In-Gel Electrophoresis in a High-Throughput Environment Richard I. Somiari, Stephen Russell, Stella B. Somiari, Anthony G. Sullivan, Darrell L. Ellsworth, Henry Brzeski, and Craig D. Shriver Statistical Analysis of 2-D Gel Patterns Francoise Seillier-Moiseiwitsch 2-DE Databases on the World Wide Web Christine Hoogland, Khaled Mostaguir, and Ron D. Appel Computer Analysis of 2-D Images Patricia M. Palagi,
1,582 citations
TL;DR: In this article, the authors review strategies to reprogram somatic cells to a pluripotent embryonic state and discuss their understanding of the molecular mechanisms of reprogramming based on recent insights into the regulatory circuitry of the PLSTM.
1,450 citations