Biomedical subjects

Joaquin Dopazo

Publications and source records attributed to Joaquin Dopazo.

7 recordsLinked to original sources

PubMed2006

Exploring the reasons for the large density of triplex-forming oligonucleotide target sequences in the human regulatory regions.

BACKGROUND: DNA duplex sequences that can be targets for triplex formation are highly over-represented in the human genome, especially in regulatory regions. RESULTS: Here we studied using bioinformatics tools several properties of triplex target sequences in an attempt to determine those that make these sequences so special in the genome. CONCLUSION: Our results strongly suggest that the unique physical properties of these sequences make them particularly suitable as "separators" between protein-recognition sites in the promoter region.

Animals↗

PubMed2006

Ontology-driven approaches to analyzing data in functional genomics.

Ontologies are fundamental knowledge representations that provide not only standards for annotating and indexing biological information, but also the basis for implementing functional classification and interpretation models. This chapter discusses the application of gene ontology (GO) for predictive tasks in functional genomics. It focuses on the problem of analyzing functional patterns associated with gene products. This chapter is divided into two main parts. The first part overviews GO and its applications for the development of functional classification models. The second part presents two methods for the characterization of genomic information using GO. It discusses methods for measuring functional similarity of gene products, and a tool for supporting gene expression clustering analysis and validation.

Cluster Analysis↗

PubMed2006

Identification of overexpressed genes in frequently gained/amplified chromosome regions in multiple myeloma.

BACKGROUND AND OBJECTIVES: Multiple myeloma (MM) is a malignancy characterized by clonal expansion of plasma cells. In 50% of the cases, the neoplastic transformation begins with a chromosomal translocation that juxtaposes the IGH gene locus to an oncogene. Gene copy number changes are also frequent in MM but less characterized than in other neoplasias. We aimed to characterize genes that are amplified and overexpressed in human myeloma cell lines (HMCL) to provide putative molecular targets for MM therapy. DESIGN AND METHODS: Nine HMCL were characterized by fluorescent in situ hybridization, comparative genomic hybridization (CGH) and cDNA microarrays for gene expression profiling and copy number changes. RESULTS: After defining the IGH-translocations present in the cell lines, we conducted expression-profiling analysis. Supervised analysis identified 166 genes with significantly different expression among the cell lines harboring MMSET/FGFR3 (4p16), MAF (16q) and CCND1 (11q13) rearrangements. Array-CGH was then performed. Five chromosomes recurrently affected by gains/amplifications in primary samples and cell lines were analyzed in detail. Sixty amplified and overexpressed genes were found and 25 (42%) of them were only overexpressed when amplified; moreover, six showed a significant association between overexpression and gain/amplification. We also found co-amplification and overexpression for genes located within the same amplicons, such as MALT1 and BCL2. INTERPRETATION AND CONCLUSIONS: Parallel analysis of gene copy numbers and expression levels by cDNA microarray in MM allowed efficient identification of genes whose expression levels are elevated because of increased copy number. This is the first time that MALT1 and BCL2 have been shown to be overexpressed and amplified in MM.

Caspases↗

PubMed2005

A predictor based on the somatic genomic changes of the BRCA1/BRCA2 breast cancer tumors identifies the non-BRCA1/BRCA2 tumors with BRCA1 promoter hypermethylation.

The genetic changes underlying in the development and progression of familial breast cancer are poorly understood. To identify a somatic genetic signature of tumor progression for each familial group, BRCA1, BRCA2, and non-BRCA1/BRCA2 (BRCAX) tumors, by high-resolution comparative genomic hybridization, we have analyzed 77 tumors previously characterized for BRCA1 and BRCA2 germ line mutations. Based on a combination of the somatic genetic changes observed at the six most different chromosomal regions and the status of the estrogen receptor, we developed using random forests a molecular classifier, which assigns to a given tumor a probability to belong either to the BRCA1 or to the BRCA2 class. Because 76.5% (26 of 34) of the BRCAX cases were classified with our predictor to the BRCA1 class with a probability of >50%, we analyzed the BRCA1 promoter region for aberrant methylation in all the BRCAX cases. We found that 15 of the 34 BRCAX analyzed tumors had hypermethylation of the BRCA1 gene. When we considered the predictor, we observed that all the cases with this epigenetic event were assigned to the BRCA1 class with a probability of >50%. Interestingly, 84.6% of the cases (11 of 13) assigned to the BRCA1 class with a probability >80% had an aberrant methylation of the BRCA1 promoter. This fact suggests that somatic BRCA1 inactivation could modify the profile of tumor progression in most of the BRCAX cases.

BRCA1 Protein↗

PubMed2005

HCAD, closing the gap between breakpoints and genes.

Recurrent chromosome aberrations are an important resource when associating human pathologies to specific genes. However, for technical reasons a large number of chromosome breakpoints are defined only at the level of cytobands and many of the genes involved remain unidentified. We developed a web-based information system that mines the scientific literature and generates textual and comprehensive information on all human breakpoints. We show that the statistical analysis of this textual information and its combination with genomic data can identify genes directly involved in DNA rearrangements. The Human Chromosome Aberration Database (HCAD) is publicly accessible at http://www.pdg.cnb.uam.es/UniPub/HCAD/.

Chromosome Breakage↗

PubMed2003

Comparing bacterial genomes through conservation profiles.

We constructed two-dimensional representations of profiles of gene conservation across different genomes using the genome of Escherichia coli as a model. These profiles permit both the visualization at the genome level of different traits in the organism studied and, at the same time, reveal features related to the genomes analyzed (such as defective genomes or genomes that lack a particular system). Conserved genes are not uniformly distributed along the E. coli genome but tend to cluster together. The study of gene distribution patterns across genomes is important for the understanding of how sets of genes seem to be dependent on each other, probably having some functional link. This provides additional evidence that can be used for the elucidation of the function of unannotated genes. Clustering these patterns produces families of genes which can be arranged in a hierarchy of closeness. In this way, functions can be defined at different levels of generality depending on the level of the hierarchy that is studied. The combined study of conservation and phenotypic traits opens up the possibility of defining phenotype/genotype associations, and ultimately inferring the gene or genes responsible for a particular trait.

Chromosome Mapping↗

PubMed2002

Identification of genes involved in resistance to interferon-alpha in cutaneous T-cell lymphoma.

Interferon-alpha therapy has been shown to be active in the treatment of mycosis fungoides although the individual response to this therapy is unpredictable and dependent on essentially unknown factors. In an effort to better understand the molecular mechanisms of interferon-alpha resistance we have developed an interferon-alpha resistant variant from a sensitive cutaneous T-cell lymphoma cell line. We have performed expression analysis to detect genes differentially expressed between both variants using a cDNA microarray including 6386 cancer-implicated genes. The experiments showed that resistance to interferon-alpha is consistently associated with changes in the expression of a set of 39 genes, involved in signal transduction, apoptosis, transcription regulation, and cell growth. Additional studies performed confirm that STAT1 and STAT3 expression and interferon-alpha induction and activation are not altered between both variants. The gene MAL, highly overexpressed by resistant cells, was also found to be expressed by tumoral cells in a series of cutaneous T-cell lymphoma patients treated with interferon-alpha and/or photochemotherapy. MAL expression was associated with longer time to complete remission. Time-course experiments of the sensitive and resistant cells showed a differential expression of a subset of genes involved in interferon-response (1 to 4 hours), cell growth and apoptosis (24 to 48 hours.), and signal transduction.

Antineoplastic Agents↗