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EST EXPRESSION PROFILE ANALYSIS 何中良 助理教授. 國立成功大學醫學院病理學科 國立成功大學分子醫學研究所 . EST. E xpressed S equence T ags. EST. E xpressed S equence T ags are partial , single-pass sequences from either end of a cDNA clone. .
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EST EXPRESSION PROFILE ANALYSIS何中良 助理教授 國立成功大學醫學院病理學科 國立成功大學分子醫學研究所
EST Expressed Sequence Tags
EST Expressed Sequence Tags are partial, single-pass sequences from either end of a cDNA clone.
Expressed Sequence Tag (EST) were generated by automated partial DNA sequencing of randomly selected cDNA clones from individual cDNA libraries.
EST sequences are real experimental data with about 1% per base error rate.
Statistics • dbEST
Cancer Genome Anatomy Project(CGAP) • Tissue • Normal • Precancer • Cancer
Cancer Genome Anatomy Project(CGAP) • Tissue preparation • Bulk • Microdissected • Cell lines • Flow sorted
Cancer Genome Anatomy Project(CGAP) • cDNA library protocols • Non-normalized • Normalized • Subtraction • (In "native" non-normalized libraries, clone frequency reflects mRNA abundance)
Cancer Genome Anatomy Project(CGAP) • cDNA library protocols
Cancer Genome Anatomy Project(CGAP) • cDNA libraries • Library finder • Library list • Library browser • cDNA Library navigator • Unified library database • Example • Summary
EST cDNA library projects • CGAP • MGC • ORESTES • And others
Serial Analysis of Gene Expression(SAGE) • Diagram 1 • Diagram 2
Serial Analysis of Gene Expression(SAGE) • Restriction enzymes • SAGE vs. EST • Shorter tags (9~13 bp) • Same sequencing power, more information • More sensitive to sequencing error • Tag-gene mapping is much messier
Unigene • Automatic clustering of ESTs • Unique set of human and mouse genes • Unigene and genome mapping • Diagram
Gene Index • TGI: TIGR Gene Indices • EGI: EuroGeneIndexes • MIPS • STACK
EST as tools (1) • Discover new genes • Genome mapping • cDNA assembly • Cluster only: Unigene • Cluster & assemble (alignment; consensus) • TGI; EGI; MIPS; STACK • Assemble & curate • EGAD
EST as tools (2) • Alternative splicing • Expression profile comparison • Digital differential display • Xprofiler • Digital Gene Expression displayer (DGED) • Virtual northern
Expression Profiles • Protein profiles • mRNA profiles
How to obtain expression profiles • Protein • Proteomics • Protien chips • mRNA • EST cDNA libraries • SAGE • Microarray
Tools to use mRNA profiles • Digital differential display • Xprofiler • Digital Gene Expression Displayer (DGED) • Virtual northern • BodyMap
Our tools • NCKU Xcrunch (eXpression profile CRUNCHer) • Digital differential display • Digital FISH • Digital Northern
Our database • Automatically download the expression profiles from Unigene Library Browser • Summary
Digital FISH (1) • Goal: To narrow down genes responsible for our favorite cancers in certain chromosomal regions. (For example: renal cancer & chromosome 3p22-23)
Digital FISH (2) • Rationale: Genes related to kidney tumors should be expressed in kidney tissue (normal and/or abnormal), i.e., should be found in kidney related EST cDNA libraries. (exceptions: viral gene products; Hormone-like effect)
Digital FISH (3) • Step 1: Get the Unigenes located in the chromosomal regions. • Step 2: Get the Unigenes from kidney-related cDNA libraries. • Step 3: What Unigenes are present in both 1 and 2?
www.binfo.ncku.edu.tw/xcrunch/ • Database • Xcrunch • Some explanation
Acknowledgement • 嚴國何 (the programmer of NCKU Xcrunch) • 李強 教授
The Mammalian Gene Collection(MGC) • NIH • To identify and sequence a representative full open reading frame (ORF) clone for each human and mouse gene
The Mammalian Gene Collection(MGC) • Libraries with up to at least 3 to 4 kb cDNA inserts • EST sequences (5’ & 3”; Accuracy same as ESTs) • Full-length candidates: submitted for full insert sequencing (at least 99.99% accuracy; Same as HGP) Back
ORF expressed sequence tags(ORESTES) • Reverse transcription-PCR using arbitrarily selected, nondegenerae primers under low-stringency • High percentage of fragments in the midportions of genes • Normalization of the sequence population
From Neto et al. Shotgun sequencing of the human transcriptome with ORF expressed sequence tags. 2000. PNAS 97(7) p3491-3496.
Full length cDNA projects • MGC • FLJ • RIKEN • DKFZ
Number of cDNA libraries > 1600 sequences Homo sapiens 6904 312 Mus musculus 536 196 Rattus norvegicus 225 40 Xenopus laevis 52 30 Danio rerio (zebrafish) 45 12 Arabidopsis thaliana 74 8 Back