Biomedical subjects

D Sudhir

Publications and source records attributed to D Sudhir.

3 recordsLinked to original sources

PubMed2005

TAGmapper: a web-based tool for mapping SAGE tags.

Serial Analysis of Gene Expression (SAGE) is an important means of obtaining quantitative information about expression of genes in different samples. Short SAGE tags are 10 nucleotides long and often contain enough information to uniquely identify the gene(s) corresponding to the tag. We have observed, however, that the currently available resources are not adequate for accurate mapping of all SAGE tags to genes. Here, we describe development of a web-based tool called TAGmapper (http://tagmapper.ibioinformatics.org), which provides a comprehensive and accurate mapping of SAGE tags to genes. We were able to map SAGE tags accurately in several instances where two other popular resources, SAGEmap (http://www.ncbi.nlm.nih.gov/projects/SAGE/) and SAGE Genie (http://cgap.nci.nih.gov/SAGE), provided incorrect or no assignment of tags to genes. Finally, we experimentally determined the expression of a subset of genes assigned by TAGmapper using DNA microarrays and/or quantitative PCR to confirm the reliability of the gene mappings. We anticipate that TAGmapper will be a useful tool in functional genomic approaches by providing accurate identification of genes in SAGE experiments.

Base Sequence↗

PubMed2005

Plasma Proteome Database as a resource for proteomics research.

Plasma is one of the best studied compartments in the human body and serves as an ideal body fluid for the diagnosis of diseases. This report provides a detailed functional annotation of all the plasma proteins identified to date. In all, gene products encoded by 3778 distinct genes were annotated based on proteins previously published in the literature as plasma proteins and the identification of multiple peptides from proteins under HUPO's Plasma Proteome Project. Our analysis revealed that 51% of these genes encoded more than one protein isoform. All single nucleotide polymorphisms involving protein-coding regions were mapped onto the protein sequences. We found a number of examples of isoform-specific subcellular localization as well as tissue expression. This database is an attempt at comprehensive annotation of a complex subproteome and is available on the web at http://www.plasmaproteomedatabase.org.

Amino Acid Motifs↗

PubMed2004

Differentially expressed genes in pancreatic ductal adenocarcinomas identified through serial analysis of gene expression.

Serial analysis of gene expression (SAGE) is a powerful tool for the discovery of novel tumor markers. The publicly available online SAGE libraries of normal and neoplastic tissues (http://www.ncbi.nlm.nih.gov/SAGE/) have recently been expanded; in addition, a more complete annotation of the human genome and better biocomputational techniques have substantially improved the assignment of differentially expressed SAGE "tags" to human genes. These improvements have provided us with an opportunity to re-evaluate global gene expression in pancreatic cancer using existing SAGE libraries. SAGE libraries generated from six pancreatic cancers were compared to SAGE libraries generated from 11 non-neoplastic tissues. Compared to normal tissue libraries, we identified 453 SAGE tags as differentially expressed in pancreatic cancer, including 395 that mapped to known genes and 58 "uncharacterized" tags. Of the 395 SAGE tags assigned to known genes, 223 were overexpressed in pancreatic cancer, and 172 were underexpressed. In order to map the 58 uncharacterized differentially expressed SAGE tags to genes, we used a newly developed resource called TAGmapper (http://tagmapper.ibioinformatics.org), to identify 16 additional differentially expressed genes. The differential expression of seven genes, involved in multiple cellular processes such as signal transduction (MIC-1), differentiation (DMBT1 and Neugrin), immune response (CD74), inflammation (CXCL2), cell cycle (CEB1) and enzymatic activity (Kallikrein 6), was confirmed by either immunohistochemical labeling of tissue microarrays (Kallikrein 6, CD74 and DMBT1) or by RT-PCR (CEB1, Neugrin, MIC1 and CXCL2). Of note, Neugrin was one of the genes whose previously uncharacterized SAGE tag was correctly assigned using TAGmapper, validating the utility of this program. Novel differentially expressed genes in a cancer type can be identified by revisiting updated and expanded SAGE databases. TAGmapper should prove to be a powerful tool for the discovery of novel tumor markers through assignment of uncharacterized SAGE tags.

Adenocarcinoma↗