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Bioinformatics and Genome Annotation

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1 Bioinformatics and Genome Annotation
Shane C Burgess

2 NIH WORKING DEFINITION OF BIOINFORMATICS AND COMPUTATIONAL BIOLOGY
July 17, 2000 Bioinformatics: Research, development, or application of computational tools and approaches for expanding the use of biological, medical, behavioral or health data, including those to acquire, store, organize, archive, analyze, or visualize such data. Computational Biology: The development and application of data-analytical and theoretical methods, mathematical modeling and computational simulation techniques to the study of biological, behavioral, and social systems.

3 Biocomputing:computational biology & bioinformatics
Gene Ontology Consortium members 3

4 Dr Fiona McCarthy Dr Susan Bridges Dr Teresia Buza Dr Nan Wang Cathy Grisham Dr Divya Pedinti Philippe Chouvarine Lakshmi Pillai

5 Sequencing is getting cheaper
Cost of human or similar sized genome Source: Richard Gibbs, Baylor College of Medicine and biocomputing becomes more of an issue.

6 Complexity Sequence itself and from all it’s compatriots and assorted microbes SNPs Transcripts (all of them…don’t forget alternative splicing, starts) CNVs Epigenetic changes to DNA Proteome (expression, epigenetics, PTMs, location, flux, enzyme kinetics) Metabolites Phenotypes Drugs B. Statistical. 1. Multiple testing problem. 2. Search space Both have potential computationally-intensive solutions (Monte Carlo/Resampling/ Permutation/Bootstrap and target/decoy). C. Information: publications are no longer the sole source of “valid” or “legitimate” information. Trusted databases and not just publications used as research sources; not just data but also community annotations etc D. Biocomputing issues: LOCAL--storage, compute power (CPUs days), RAM; DISTANT– linking, data movement, cyberinfrastucture (hard, soft and human). E. How and who?

7 Titus Brown, Mich. SU

8 Storage costs A. Simple Storage Service (S3) e.g. Amazon. For the first 50 TB = 15 US cents/Gb ($7,500/50 TB) plus pay for data transfer and operations. VS Buy, store and scale as needed e.g. Web Object Scaler (WOS) Immediate or “longer” term solution Putting Genomes in the Cloud. Making data sharing faster, easier and more scalable. By M. May, May 18, 2010.

9 10 Gigabits (Gb)/second

10 Annotation: Nomenclature, Structural & Functional
Structural Annotation: Open reading frames (ORFs) predicted during genome assembly predicted ORFs require experimental confirmation Functional Annotation: annotation of gene products = Gene Ontology (GO) annotation initially, predicted ORFs have no functional literature and GO annotation relies on computational methods (rapid) functional literature exists for many genes/proteins prior to genome sequencing Gene Ontology annotation does not rely on a completed genome sequence

11 Chicken Gene Nomenclature
Livestock Gene Nomenclature: Jim Reecy et al., International Society for Animal Genetics from 26th – 30th July 2010, Edinburgh Chicken Gene Nomenclature 1995: chicken gene nomenclature will follow HGNC guidelines 2007: chicken biocurators begin assigning standardized nomenclature 2008: first CGNC report; NCBI begins using standardized nomenclature & CGNC links 2010: first dedicated chicken gene nomenclature biocurator; NCBI/AgBase/Marcia Miller – structural annotation & nomenclature for MHC regions (chr 16) Chicken gene nomenclature database – UK & US databases sharing and co-coordinating data.

12 Available via BirdBase & AgBase

13 Experimental Structural genome annotation Proteogenomic mapping

14 Problems with Current Structural Annotation Methods
EST evidence is biased for the ends of the genes Computational gene finding programs Misidentify some, and especially short, genes, genes. Overlook exons Incorrectly demarcate gene boundaries, especially splice junctions Annotation of the open reading frames (ORFs) (i.e., gene prediction) in genomes is most often performed computationally based on features in the nucleic acid sequence. Homology searches method

15 Proteogenomic Mapping
Combines genomic and proteomic data for structural annotation of genomes First reported by Jaffe et al. at Harvard in 2004 in bacteria McCarthy et al first applied in chicken (one of the first uses in a eukaryote; the other two in human). Improves genome structural annotation based on expressed protein evidence Confirms existence of predicted protein-coding gene Identifies exons missed by gene finder Corrects incorrect boundaries of previously identified genes Identifies new genes that the gene finding programs missed

16 CCV genome was sequenced in 1992
But only 12 of predicted 76 ORFs confirmed to exist as proteins. Confirmed 37/76. Identified 17 novel ORFs that were not predicted.

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18 Structural Annotation of the Chicken Genome
Location of genes on the genome Computational gene finding programs such as Gnomen (NCBI) based on Markov Models and also use ESTs Known proteins Sequence conservation

19 ePST Generation Process
Peptide nucleotide sequence chromosome Map peptide nucleotide sequence to chromosome

20 Search against protein Database
Biological Sample Trypsin Digestion LC ESI-MS/MS Data Search against protein Database Search against genome translated in 6 reading frame Peptide matches Peptide matches Generate ePST (expressed PeptideSequence Tags) from peptides matching genome only Confirm predicted protein-coding gene Correction / validation of genome annotation Novel protein-coding gene

21 ePST Generation Process
Peptide nucleotide sequence Stop codon chromosome Locate first downstream in-frame stop codon or canonical splice junction

22 ePST Generation Process
Peptide nucleotide sequence Stop codon chromosome Locate upstream canonical splice junction or in-frame stop

23 ePST Generation Process
Peptide nucleotide sequence Stop codon chromosome Start codon Find 1st start codon between in-frame stop and peptide

24 ePST Generation Process
chromosome Use splice junction or in-frame start as beginning of ePST

25 ePST Generation Process
chromosome ePST coding nucleotide sequence Translate Expressed Peptide Sequence Tag (ePST) amino acid sequence

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30 Functional annotation

31 2 4 6 8 10 12 14 16 18 70 75 80 85 90 95 00 05 No. x 106 No. 5000 10000 15000 20000 25000 ‘00 ‘01 ‘02 ‘03 ‘04 ‘05 ‘06 ‘07 ‘08 ‘09 YEAR

32 Functional Understanding
Canonical and other Networks Ontologies Functional Understanding GO Cellular Component GO Biological Process GO Molecular Function BRENDA Pathway Studio 5.0 Ingenuity Pathway Analyses Cytoscape Interactome Databases

33 Biological interpretation
Gene Ontology Network Modeling Derived Implied Physiology (= Cellular Component + Biological Process + Molecular Function)

34 What is the Gene Ontology?
“a controlled vocabulary that can be applied to all organisms even as knowledge of gene and protein roles in cells is accumulating and changing” the de facto standard for functional annotation assign functions to gene products at different levels, depending on how much is known about a gene product is used for a diverse range of species structured to be queried at different levels, eg: find all the chicken gene products in the genome that are involved in signal transduction zoom in on all the receptor tyrosine kinases human readable GO function has a digital tag to allow computational analysis of large datasets COMPUTATIONALLY AMENABLE ENCYCLOPEDIA OF GENE FUNCTIONS AND THEIR RELATIONSHIPS

35 GO is the “encyclopedia” of gene functions captured, coded and put into a directed acyclic graph (DAG) structure. In other words, by collecting all of the known data about gene product biological processes, molecular functions and cell locations, GO has become the master “cheat-sheet” for our total knowledge of the genetic basis of phenotype. Because every GO annotation term has a unique digital code, we can use computers to mine the GO DAGs for granular functional information. Instead of having to plough through thousands of papers at the library and make notes and then decide what the differential gene expression from your microarray experiment means as a net affect, the aim is for GO to have all the biological information captured and then retrieve it and compile it with your quantitative gene product expression data and provide a net affect.

36 Use GO for……. Determining which classes of gene products are over-represented or under-represented. Grouping gene products. Relating a protein’s location to its function. Focusing on particular biological pathways and functions (hypothesis-testing).

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38 Many people use “GO Slims” which capture only high-level terms which are more often then not extremely poorly informative and not suitable for hypothesis-testing. “GO Slim” In contrast, we need to use the deep granular information rich data suitable for hypothesis-testing

39 Sourcing displaying GO annotations: secondary and tertiary sources.

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41 GO Consortium: Reference Genome Project
Limited resources to GO annotate gene products for every genome rely on computational GO annotations most robust method is to transfer GO between orthologs Reference genome project: goal is to produce a “gold standard” manually biocurated GO annotation dataset for orthologous genes 12 reference genomes – chicken is only agricultural species Chicken RGP contributions provided via USDA CSREES MISV

42 RGP & Taxonomy checks Transferring GO annotation between orthologs requires: determining orthologs – computational prediction followed by manual curation developing ‘sanity’ checks to ensure transferred functions make sense phylogenetically (eg. no lactating chickens!)

43 Further taxon checking comments may be added here, or contact the AgBase database.

44 AgBase Quality Checks & Releases
AgBase Biocurators ‘sanity’ check AgBase biocuration interface ‘sanity’ check & GOC QC AgBase database GO analysis tools Microarray developers ‘sanity’ check UniProt db QuickGO browser GO analysis tools Microarray developers EBI GOA Project ‘sanity’ check: checks to ensure all appropriate information is captured, no obsolete GO:IDs are used, etc. ‘sanity’ check & GOC QC Public databases AmiGO browser GO analysis tools Microarray developers GO Consortium database

45 Gene Products annotated
Comparing AgBase & EBI-GOA Annotations 14,000 computational manual - sequence 12,000 manual - literature 10,000 Gene Products annotated 8,000 Complementary to EBI-GOA: Genbank proteins not represented in UniProt & EST sequences on arrays 6,000 4,000 2,000 AgBase EBI-GOA AgBase EBI-GOA Chick Chick Cow Cow Project

46 Contribution to GO Literature Biocuration
AgBase EBI GOA Chicken 97.82% EBI-IntAct Roslin HGNC < 0.50% UCL-Heart project MGI Cow Reactome 88.78% < 1.50%

47 INPUT: functional genomics data (e.g. Microarray data) GOanna Biocuration from literature Manual interpretation of GOanna output gene products with NO orthologs OR with orthologs but NO GO annotations GOModeler Generic: qualitative data presentation. Analysis can only be changed if user has programming skills Specific: user-defined, hypothesis-driven, quantitative data presentation must wait on experimental evidence or new electronic inference NO literature or specialist knowledge that can be used to make GO annotations gene products with orthologs and GO annotations gene products with NO GO annotations gene products with GO annotations BLAST output biocurated annotations from literature or specialist knowledge GOSlimViewer GORetriever data visualization ArrayIDer GOanna2ga comprehensive GO annotation (existing GO analysis programs) GA2GEO GAQ Score Figure 4: GO Tools available at the AgBase website. We have added tools to help users get comprehensive GO annotations for functional modeling (indicated by blue boxes) and extended the ID types that existing tools (green boxes) accept. The inset shows the types of IDs now accepted.

48 To request a workshop contact
2010 GO Training Opportunities - on site training by request/interest - webinar: notification via ANGENMAP & GO discussion groups To request a workshop contact Fiona McCarthy OR

49 GO training 2009 Workshop hosts: ISU – Dr Susan Lamont
Workshop Surveys 10 20 30 40 50 60 Topics covered were relevant Topics were well explained I am confident in using GO for modeling I am confident I can get GO questions answered I would recommend this workshop % of respondents strongly agree agree uncertain disagree strongly disagree GO training 50 100 150 200 2007 2008 2009 Year workshops offered No. of people Annual Cumulative 2009 Workshop hosts: ISU – Dr Susan Lamont NCSU – Dr Hsiao-Ching Liu

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51 Number of participants: 25 Number of arrays: 22 Number of votes: 41
Chicken Array Usage Number of participants: 25 Number of arrays: 22 Number of votes: 41 Bovine array usage Number of participants: 26 Number of arrays: 26 Number of votes: 42 ARK-Genomics Affymetrix Agilent 44K array UD 7.4K Metabolic/Somatic UD_Liver_3.2K Arizona 20.7K Neuroendocrine UIUC 13.2K Agilent 44k Bovine Total Leukocyte cDNA Affymetrix UIUC 7,872-element

52 Quality improvement Microarray annotations

53 Most microarray analysis tools do not readily accept EST clone names (abundantly on arrays).
Manual re-annotation of microarrays is impracticable Retrieves the most recent accession mapping files from public databases based on EST clone names or accessions and rapidly generates database accessions. Fred Hutchinson Cancer Research Centre 13K chicken cDNA array structurally re-annotated 55% of the array; decreased non-chicken functional annotations by 2 fold; identified 290 pseudogenes, 66 of which were previously incorrectly annotated.

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55 Zhou H, Lamont SJ: Global gene expression profile after Salmonella enterica Serovar enteritidis challenge in two F8 advanced intercross chicken lines. Cytogenet Genome Res 2007;117: (DOI: / )

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59 Increased the pathway coverage of several major immune response pathways and provided more comprehensive modelling of signalling pathways e.g. FAS :originally not annotated but now pathways involving FAS identified. Confirm and consolidate previous suggestions that CD3e, IL-1β, and CCL5 differential expression involved in the immune response to SE. Chicken-specific functional annotation of these genes allowed identification of these gene’s related pathways with statistical confidence. Identified additional genes involved in major immune pathways important in bacterial gut disease but not identified in the original work e.g. tyrosine phosphatase type IVA member 1 (PTP4A1); CD28; T-cell co-stimulator (ICOS, CD287) and NK-lysin and associated pathway genes.

60 Bacterial functional genomic responses to structural differences in explosive compounds.
KTR9 and V. fischeri proteomics

61 Quantifying re-annotation
Metrics Granularity Specificity # previous annotations # chicken annotations # re-annotations # human/mouse annotations Quality Gene Ontology Annotation Quality (GAQ) score

62 Reads in annotated gene regions + 20 kb radius
Reads in “RNAFAR” regions i.e. clustered reads forming novel transcripts (these reads do not belong to any gene model the reference set and can either be assigned to neighboring gene models, if they are within a specified threshold radius, or assigned their own predicted transcript model. Repeats with > 10 alignments Reads overlapping annotated repeat regions Unmapped reads Other (regulatory, etc. do not include reads discarded as poor quality). DoD: Bobwhite Quail Toxicogenomics Mean GAQ score 62

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64 GO Cellular Component DAG

65 Differential Detergent Fractionation
DDF Fraction 1 2 3 4 2007. Non-electrophoretic differential detergent fractionation proteomics using frozen whole organs. Rapid Commun Mass Spectrom 21: 2007. Sequential detergent extraction prior to mass spectrometry analysis. Methods in Molecular Medicine: Proteomic analysis of membrane proteins. Humana Press. 117 (1-4): 2005. Differential detergent fractionation for non-electrophoretic eukaryote cell proteomics. Journal of Proteome Research. 4 (2),

66 M C N Sub-cellular localization of pro-PCD proteins. B-cells Stroma
One mechanism controlling PCD is the release of “pro-death” proteins mitochondria into the cytoplasm or nucleus. B-cells Stroma C CytC Apaf1 AMID EndoG AIF Smac M N

67 Neoplastic compared to Hyperplastic
100000 mRNA 10000 1000 100 10 1 IL-2 IL-4 IL-6 IL-8 IL-10 IL-12 IL-13 Neoplastic compared to Hyperplastic lymphoma cells (%) IL-18 IFNg TGFb CTLA-4 GPR-83 SMAD-7 4 Protein 3 IL-10 2 IL-12 1 IL-6 IL-13 IL-8 IL-2 IL-4 IL-18 TGFb CTLA-4 GPR-83 -1 IFNg SMAD-7 -2 -3 Cancer Immunology and Immunotherapy, : 67

68 IL-18 distribution: it matters where proteins are
2 3 4 IL-18 distribution: it matters where proteins are 1 2 3 4 DDF Fraction Neoplastic Lymphocytes (T-reg) Hyperplastic Lymphocytes Extracellular Nuclear 15 20 25 30 35 5 10 10 20 30 40 50 60 70 80 Shack et al., Cancer Immunology and Immunotherapy, : 68

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70 Pig Bindu Nanduri Translation to clinical research
Total mRNA and protein expression was measured from quadruplicate samples of control, electroscalple and harmonic scalple-treated tissue. Differentially-expressed mRNA’s and proteins identified using Monte-Carlo resampling1. Using network and pathway analysis as well as Gene Ontology-based hypothesis testing, differences in specific phyisological processes between electroscalple and harmonic scalple-treated tissue were quantified and reported as net effects. (1) Nanduri, B., P. Shah, M. Ramkumar, E. A. Allen, E. Swaitlo, S. C. Burgess*, and M. L. Lawrence* Quantitative analysis of Streptococcus Pneumoniae TIGR4 response to in vitro iron restriction by 2-D LC ESI MS/MS. Proteomics 8,

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72 Proportional distribution of protein functions differentially-expressed by Electro and Harmonic Scalpel HYPOTHESIS TERMS Total differentially-expressed proteins: 433 Harmonic Scalpel Total differentially-expressed proteins: 509 Electroscalpel immunity (primarily innate) inflammation Wound Healing Lipid metabolism response to Thermal Injury angiogenesis hemorrhage

73 Net functional distribution of differentially-expressed proteins
Harmonic Scalpel Electroscalpel hemorrhage sensory response to pain angiogenesis response to thermal injury Lipid metabolism Wound healing classical inflammation (heat, redness, swelling, pain, loss of function) immunity (primarily innate) 8 6 4 2 2 4 6 Relative bias

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