Extranuclear detection of histones and nucleosomes in activated human lymphoblasts as an early event in apoptosis. Issue 9 (12th August 2004)

• Record Type: Journal Article
• Authors: Gabler, C; Blank, N; Hieronymus, T; Schiller, M; Berden, J H M; Kalden, J R; Lorenz, H-M
• Is Part Of: Annals of the rheumatic diseases. Volume 63:Issue 9(2004)
• Page Start: 1135
• Page End: 1144
• Publication Date: 2004-08-12
• Subjects: AxV, annexin V -- ELISA, enzyme linked immunosorbent assay -- H1, H2A, H2B, H3, H4, histone 1, 2A, 2B, 3, 4 -- IL2, interleukin 2 -- med, medium -- PBMC, peripheral blood mononuclear cells -- PBST, phosphate buffered saline with 0.1% (v/v) Tween 20 -- PI, propidium iodide -- R10, RPMI 1640 medium (R10) supplemented with 10% fetal calf serum, 4 mM l-glutamine, 10 mM HEPES buffer, 100 U/ml penicillin, 100 μg/ml streptomycin -- SDS-PAGE, sodium dodecyl sulphate-polyacrylamide gel electrophoresis -- SLE, systemic lupus erythematosus; T lymphocytes -- lupus -- antigens -- apoptosis; Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/ard.2003.011452
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Objective: To evaluate the presence of histones and nucleosomes in cell lysates of freshly isolated peripheral blood mononuclear cells (PBMC), fully activated lymphoblasts, or lymphoblasts after induction of apoptosis. Methods: Each histone class (H1, H2A, H2B, H3, and H4) was detected by western blot analysis with specific antibodies. Annexin V/propidium iodide (PI) staining was performed for each treatment to distinguish viable, early, and late apoptotic, and necrotic cells. DNA degradation was evaluated by PI staining in a hypotonic buffer. Results: All five histones were detected in cell lysates of activated lymphoblasts in higher concentrations than in lysates of PBMC. An additional significant increase of H2A, H2B, H3, H4, and complete nucleosomes in cell lysates of lymphoblasts was found during interleukin (IL)2 deprivation for 8 or 24 hours. The content of these histones or nucleosomes in cell lysates decreased after delayed IL2 readdition. H1 content in cell lysates was not affected by IL2 deprivation or addition. Quantities of H2A, H2B, H3, and H4 in cell lysates correlated significantly with signs of early apoptosis. UV-B light exposure or etoposide treatment of lymphoblasts resulted in a distinct increase for each histone class in cell lysates compared with standard curves. No bands for post-translationally modified histones were detected in cell lysates in contrast with signals in nuclear preparations. Conclusion: Extranuclear accumulation of histones and nucleosomes is an early event of apoptosis in human lymphoblasts. Dysregulation of early apoptosis might support the induction of autoimmunity against nuclear components.