Downregulation of genes involved in DNA repair and differential expression of transcription regulators and phosphatases precede IgM-induced apoptosis in the Burkitt's lymphoma cell line BL60-2.
Apoptosis of lymphocytes recognizing self-antigens is an essential mechanism to protect the organism against autoimmune diseases. Programmed cell death of susceptible B cells occurs in response to surface IgM cross-linking mediated by self-antigens. This effect can be mimicked in the Burkitt's lymphoma line BL60-2 by addition of anti-IgM antibodies. In order to identify genes with differential expression in response to the apoptotic stimulus, total RNA prepared from BL60-2 cells before and at different points in time after IgM cross-linking was used for Atlas arrays, high-density oligonucleotide microarrays (GeneChip arrays, Affymetrix) and in RNase protection assays (RPA). One of our major observations was the downregulation of six genes involved in the ligation of DNA strand breaks, like DNA ligases and DNA-PK, indicating a shutdown of DNA repair mechanisms in apoptotic cells. In addition, we found changes on mRNA level for several transcription regulators, including early growth response genes 1 and 2, TAFII30 and topoisomerase I. Furthermore, we show accumulation of mRNA for the phosphatases CD45 and DUSP5 in anti-IgM stimulated BL60-2 cells. Our data provide a basis for further analysis of the differentially expressed genes and their roles in IgM-induced B cell death as well as in apoptosis in other cellular systems.
Schories
Barbara
B
Department of Hematology, Oncology and Tumorimmunology, Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, D-13122 Berlin, Germany.
Janz
Martin
M
Dörken
Bernd
B
Bommert
Kurt
K
D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D045744:Cell Line, Tumor; D053938:DNA Fragmentation; D017931:DNA Primers; D004260:DNA Repair / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D015151:Immunoblotting; D007075:Immunoglobulin M / Q000276:immunology; D008163:Luminescent Measurements; D020411:Oligonucleotide Array Sequence Analysis; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D012313:RNA / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases
D017931:DNA Primers; D007075:Immunoglobulin M; D012313:RNA; D012260:Ribonucleases; D010744:Phosphoric Monoester Hydrolases