Biomedical subjects

Steffen Möller

Publications and source records attributed to Steffen Möller.

11 recordsLinked to original sources

PubMed2006

Fine mapping of collagen-induced arthritis quantitative trait loci in an advanced intercross line.

The generation of advanced intercross lines (AIL) is a powerful approach for high-resolution fine mapping of quantitative trait loci (QTLs), because they accumulate much more recombination events compared with conventional F2 intercross and N2 backcross. However, the application of this approach is severely hampered by the requirements of excessive resources to maintain such crosses, i.e., in terms of animal care, space, and time. Therefore, in this study, we produced an AIL to fine map collagen-induced arthritis (CIA) QTLs using comparatively limited resources. We used only 308 (DBA/1 x FVB/N)F11/12 AIL mice to refine QTLs controlling the severity and onset of arthritis as well as the Ab response and T cell subset in CIA, namely Cia2, Cia27, and Trmq3. These QTLs were originally identified in (DBA/1 x FVB/N)F2 progeny. The confidence intervals of the three QTLs were refined from 40, 43, and 48 Mb to 12, 4.1, and 12 Mb, respectively. The data were complemented by the use of another QTL fine-mapping approach, haplotype analysis, to further refine Cia2 into a 2-Mb genomic region. To aid in the search for candidate genes for the QTLs, genome-wide expression profiling was performed to identify strain-specific differentially expressed genes within the confidence intervals. Of the 1396 strain-specific differentially expressed genes, 3, 3, and 12 genes were within the support intervals of the Cia2, Cia27, and Trmq3, respectively. In addition, this study revealed that Cia27 and Trmq3 controlling anti-CII IgG2a Ab and CD4:CD8 T cell ratio, respectively, also regulated CIA clinical phenotypes.

Animals↗

PubMed2006

Agents in bioinformatics, computational and systems biology.

The adoption of agent technologies and multi-agent systems constitutes an emerging area in bioinformatics. In this article, we report on the activity of the Working Group on Agents in Bioinformatics (BIOAGENTS) founded during the first AgentLink III Technical Forum meeting on the 2nd of July, 2004, in Rome. The meeting provided an opportunity for seeding collaborations between the agent and bioinformatics communities to develop a different (agent-based) approach of computational frameworks both for data analysis and management in bioinformatics and for systems modelling and simulation in computational and systems biology. The collaborations gave rise to applications and integrated tools that we summarize and discuss in context of the state of the art in this area. We investigate on future challenges and argue that the field should still be explored from many perspectives ranging from bio-conceptual languages for agent-based simulation, to the definition of bio-ontology-based declarative languages to be used by information agents, and to the adoption of agents for computational grids.

Artificial Intelligence↗

PubMed2006

Definition of a 1.06-Mb region linked to neuroinflammation in humans, rats and mice.

Unbiased identification of susceptibility genes might provide new insights into pathogenic mechanisms that govern complex inflammatory diseases such as multiple sclerosis. In this study we fine mapped Eae18a, a region on rat chromosome 10 that regulates experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. We utilized two independent approaches: (1) in silico mapping based on sequence similarity between human multiple sclerosis susceptibility regions and rodent EAE quantitative trait loci and (2) linkage mapping in an F10 (DA x PVG.AV1) rat advanced intercrossed line. The linkage mapping defines Eae18a to a 5-Mb region, which overlaps one intergenomic consensus region identified in silico. The combined approach confirms experimentally, for the first time, the accuracy of the in silico method. Moreover, the shared intersection between the results of both mapping techniques defines a 1.06-Mb region containing 13 candidate genes for the regulation of neuroinflammation in humans, rats, and mice.

Animals↗

PubMed2006

Multiple sclerosis therapy monitoring based on gene expression.

Multiple sclerosis (MS) is the most prevalent chronic autoimmune, neurodegenerative disorder of the central nervous system (CNS). Despite substantial progress, treatment of MS and other autoimmune diseases is only moderately effective. It is anticipated that the treatment of autoimmune diseases with single drugs or biological approaches will in the future be complemented, or even replaced, by combination therapies, which include immunomodulation, elimination of infectious triggers and tissue repair. One proclaimed goal of biomedical research and clinical practice is the discovery of sets of genes with expression that correlates with successful outcomes of drug therapy, or with unfortunate side effects. Such information has direct consequences for selection, refinement or development of treatments and will soon be translated into clinical trials. The genome-wide RNA profile of an individual represents one complement to the comprehensive determination of disease- or drug response-related elements; comparable to a 'sentinel' method, it serves as a large-scale approach to MS biology. This work reviews the state of the art in MS research at the transcriptome level applying genomewide screening methods. It discusses implications in understanding disease pathogenicity, diagnostic markers, the identification of new therapeutic targets and a classification of patients towards the advent of tailored therapies.

Biomarkers↗

PubMed2006

Comparative genomics for the investigation of autoimmune diseases.

The complete DNA sequence of the human genome and of several related mammals are now available, due to the investments of enormous resources and advances in sequencing technology. Novel technologies have been developed to compare multiple genomes with each other, thus specifying regions of sequence similarity among mammals and with their pathogens. Larger blocks of sequence similarity (syntenic regions) have been determined and made publicly available. In many ways, novel insights can be gained by such data when combining external genetic or clinical information for these syntenic loci. These novel tools have proven to be successful in inferring functional equivalence between loci of multiple genomes. This review reports on the role of comparative genomics in research on autoimmune diseases, a field with strong dependencies on animal models of human diseases and the problem of an adequate information transfer between multiple organisms and research areas.

Animals↗

PubMed2005

Cytoskeletal rearrangements in synovial fibroblasts as a novel pathophysiological determinant of modeled rheumatoid arthritis.

Rheumatoid arthritis is a chronic inflammatory disease with a high prevalence and substantial socioeconomic burden. Despite intense research efforts, its aetiology and pathogenesis remain poorly understood. To identify novel genes and/or cellular pathways involved in the pathogenesis of the disease, we utilized a well-recognized tumour necrosis factor-driven animal model of this disease and performed high-throughput expression profiling with subtractive cDNA libraries and oligonucleotide microarray hybridizations, coupled with independent statistical analysis. This twin approach was validated by a number of different methods in other animal models of arthritis as well as in human patient samples, thus creating a unique list of disease modifiers of potential therapeutic value. Importantly, and through the integration of genetic linkage analysis and Gene Ontology-assisted functional discovery, we identified the gelsolin-driven synovial fibroblast cytoskeletal rearrangements as a novel pathophysiological determinant of the disease.

Animals↗

PubMed2005

Collection of soluble variants of membrane proteins for transcriptomics and proteomics.

The existence of a soluble splice variant for a gene encoding a transmembrane protein suggests that this gene plays a role in intercellular signalling, particularly in immunological processes. Also, the absence of a splice variant of a reported soluble variant suggests exclusive control of the solubilisation by proteolytic cleavage. Soluble splice variants of membrane proteins may also be interesting targets for crystallisation as their structure may be expected to preserve, at least partially, their function as integral membrane proteins, whose structures are most difficult to determine. This paper presents a dataset derived from the literature in an attempt to collect all reported soluble variants of membrane proteins, be they splice variants or shedded. A list of soluble variants is derived in silico from Ensembl. These are checked on their presence in multiple organisms and their number of membranespanning regions is inspected. The findings then are confirmed by a comparison with identified proteins of a recent global proteomics study of human blood plasma. Finally, a tool to determine novel soluble variants by proteomics is provided.

Animals↗

PubMed2004

In silico fine-mapping: narrowing disease-associated loci by intergenomics.

UNLABELLED: Genetic linkage and association studies define quantitative trait loci (QTLs) and susceptibility loci (SLs) that influence the phenotype of polygenic traits. A web-accessible application was created to identify intergenomic consensuses to fine map QTLs and SLs in silico and select particularly promising candidate genes for such traits. Furthermore, this approach offers an empirical evaluation of animal models for their applicability to the study of human traits. AVAILABILITY: http://qtl.pzr.uni-rostock.de/qtlmix.php CONTACT: serrano@pzr.uni-rostock.de.

Animals↗

PubMed2004

Non-linear conversion between genetic and physical chromosomal distances.

UNLABELLED: A supervised nonlinear interpolation significantly improves the reliability of conversions from genetic distances to physical distances as compared with the linear ones. A webaccessible application was created that addresses this question with a graphical presentation that may be wrapped by local installations. MOTIVATION: Genetic linkage maps and radiation hybrid (RH) maps are based on the rate of uncoupling between linked genetic markers. These are usually measured in centiMorgan (cM) when uncoupling is originated by natural recombination or in centiRay (cR) for chromosomes that are irradiated artificially to separate the markers. Physical maps arise from genome-wide DNA sequencing and are measured in bp. This work was originally motivated as an extension of the software application Expressionview (Fischer et al., 2003), exploring its spectrum of appliance combining different mapping systems. The relationship between physical and genetic maps is known to be not always linear (Yu et al., 2001). The shift from the linear model seems to depend on local idiosyncrasies of the chromosomes and the kind of genetic map used. The present application addresses this problem for the first time. AVAILABILITY: http://qtl.pzr.uni-rostock.de/cartographer.php

Algorithms↗

PubMed2004

Selecting SNPs for association studies based on population frequencies: a novel interactive tool and its application to polygenic diseases.

Common complex polygenic diseases as autoimmune diseases have not been completely understood on a molecular level. While many genes are known to be involved in the pathways responsible for the phenotype, explicit causes for the susceptibility of the disease remain to be elucidated. The susceptibility to disease is thought to be the result of genetic epistatic interactions between common polymorphic genes. This polymorphism is mostly caused by single nucleotide polymorphisms (SNPs). Human subpopulations are known to differ in the susceptibility to the diseases and generally in the distribution of single nucleotide polymorphisms. The here presented approach retrieves SNPs with the most divergent frequencies for selected human subpopulations to help defining properties for the experimental verification of SNPs within defined regions. A web-accessible program implementing this approach was evaluated for multiple sclerosis (MS), a common human polygenic disease. A link to a summary of data from "The SNP Consortium" (TSC) with sex-dependencies of SNPs is available. Associations of SNPs to genes, genetic markers and chromosomal loci are retrieved from the Ensembl project. This tool is recommended to be used in conjunction with microarray analyses or marker association studies that link genes or chromosomal loci to particular diseases.

Gene Frequency↗

PubMed2003

Expressionview: visualization of quantitative trait loci and gene-expression data in Ensembl.

We present here a software tool for combined visualization of gene-expression data and quantitative trait loci (QTL). The application is implemented as an extension to the Ensembl project and caters for a direct transition from microarray experiments of gene or protein expression levels to the genomic context of individual genes and QTL. It supports the visualization of gene clusters and the selection of functional candidate genes in the context of research on complex traits.

Animals↗