Biomedical subjects

Carsten P Schepp

Publications and source records attributed to Carsten P Schepp.

5 recordsLinked to original sources

PubMed2007

Large-scale mapping of mutations affecting zebrafish development.

BACKGROUND: Large-scale mutagenesis screens in the zebrafish employing the mutagen ENU have isolated several hundred mutant loci that represent putative developmental control genes. In order to realize the potential of such screens, systematic genetic mapping of the mutations is necessary. Here we report on a large-scale effort to map the mutations generated in mutagenesis screening at the Max Planck Institute for Developmental Biology by genome scanning with microsatellite markers. RESULTS: We have selected a set of microsatellite markers and developed methods and scoring criteria suitable for efficient, high-throughput genome scanning. We have used these methods to successfully obtain a rough map position for 319 mutant loci from the Tübingen I mutagenesis screen and subsequent screening of the mutant collection. For 277 of these the corresponding gene is not yet identified. Mapping was successful for 80 % of the tested loci. By comparing 21 mutation and gene positions of cloned mutations we have validated the correctness of our linkage group assignments and estimated the standard error of our map positions to be approximately 6 cM. CONCLUSION: By obtaining rough map positions for over 300 zebrafish loci with developmental phenotypes, we have generated a dataset that will be useful not only for cloning of the affected genes, but also to suggest allelism of mutations with similar phenotypes that will be identified in future screens. Furthermore this work validates the usefulness of our methodology for rapid, systematic and inexpensive microsatellite mapping of zebrafish mutations.

Animals↗

PubMed2005

The heat shock protein Hsp70 enhances antigen-specific proliferation of human CD4+ memory T cells.

Heat shock proteins (HSP) can interact with a wide variety of peptides and the resulting HSP:peptide complexes are known to be highly immunogenic. The ability of HSP:peptide complexes to elicit CD8+ T cell responses by cross-presentation of exogenous antigen via MHC class I is well known. In contrast, their role in the activation of CD4+ T cells is less clearly defined, although several recent studies in mice and T cell lines suggest an involvement of HSP in the presentation of antigenic peptides via MHC class II. In this study we have investigated the potential of antigenic peptides from tetanus toxin and influenza hemagglutinin complexed to the human stress-inducible Hsp70 to enhance activation and proliferation of human memory CD4+ T cells. Hsp70:peptide complexes were found to amplify the proliferation of antigen-specific CD4+ T cells as confirmed by HLA-DR tetramer staining. Complex formation of the antigenic peptide with Hsp70 was absolutely required to elicit an antigen-specific amplification. This effect was most pronounced at low doses of antigen and decreasing APC/CD4+ T cell ratios. Taken together, we show the potential of Hsp70 to enhance antigen-specific CD4+ T cell proliferation and to increase the immunogenicity of presented peptides in human CD4+ T cells.

Amino Acid Sequence↗

PubMed2004

Determination of the peptide binding motif and high-affinity ligands for HLA-DQ4 using synthetic peptide libraries.

Juvenile idiopathic arthritis (JIA) is considered to be an autoimmune disease. Various human leukocyte antigen (HLA) associations for different subgroups of this heterogeneous disease have been found. For early-onset pauciarticular arthritis (now oligoarthritic JIA), a strong association with the HLA class II haplotype DQA1*0401/DQB1*0402 (DQ4) has been described. We determined the peptide-binding specificities of this HLA-DQ molecule by screening a synthetic acetylated nonapeptide amide library with one defined and eight random sequence positions. A characteristic binding motif could be deduced. By use of these data, we designed defined specific nonapeptides and identified high-affinity ligands binding to HLA-DQ4. The peptide binding motif of HLA-DQ4 is very similar to the motif of HLA-DQ7, also associated with oligoarthritic JIA. It is, however, different from binding motifs of neutral or protective HLA-DQ molecules. Our results further support the idea of differential peptide presentation in the pathogenesis of oligoarthritic JIA.

Amino Acid Motifs↗

PubMed2004

Autoantibodies in juvenile idiopathic arthritis: glucose-6-phosphate isomerase is not a specific target.

OBJECTIVE: Antibodies recognizing the ubiquitous cytosolic enzyme glucose-6-phosphate isomerase (GPI) cause arthritis in the K/BxN mouse model. Studies have shown that these antibodies are not specific for rheumatoid arthritis (RA) in humans. We evaluated GPI as a target of autoantibodies in juvenile idiopathic arthritis (JIA). METHODS: We studied 324 serum and 48 synovial fluid (SF) samples from 103 patients with JIA, 36 with RA, and 8 with arthralgia and 11 controls. Anti-GPI antibodies were assessed by densitometrically evaluating immunoblots and ELISA using native and recombinant GPI. We determined the GPI activity of the soluble antigen in serum and SF. RESULTS: Although several samples contained anti-GPI-IgG antibodies, this was not specific for JIA or its subgroups, or for RA. Other proteins in the GPI preparation were also frequently recognized by antibodies. Additionally, we observed increased GPI activity in patients with the systemic manifestation of JIA, but not in other patients. Neither anti-GPI concentrations nor GPI activity were associated with disease activity. CONCLUSION: In addition to the findings in RA, our results indicate that GPI is not a general target of autoantibodies in JIA.

Adolescent↗

PubMed2003

Retinal defects in the zebrafish bleached mutant.

The recessive zebrafish mutant bleached has, apart from its defects in pigmentation, a heritable defect leading to larval blindness. Here, we analyze the retina of homozygous bleached larvae, employing morphological and electrophysiological methods. Electroretinography revealed a complete lack of electrical signals in response to light. Histological analysis of mutant retinae showed a severely affected outer retina with a hypopigmented pigment epithelium and a disorganized outer nuclear layer containing few or no intact photoreceptors. Using the TUNEL assay for cell death detection, we noticed a strong increase of apoptotic cells in all retinal cell layers, starting in young larvae even before retinal support of visual function. At later stages cell death is most pronounced at the marginal zone, where new cells are constantly added to the retina. At early stages increased apoptosis is mainly confined to the retina, while at later stages elevated cell death is al so apparent in extra-retinal tissues, particularly in the brain. Hence, the lack of visual responses in homozygous bleached larvae can be attributed to a severe defect of the outer retina, preceded by increased levels of apoptotic cell death in all retinal cell layers.

Animals↗