Identification of apoptosis-associated proteins in a human Burkitt lymphoma cell line. Cleavage of heterogeneous nuclear ribonucleoprotein A1 by caspase 3.

Apoptosis or programmed cell death is essential in the process of controlling lymphocyte growth and selection. We identified proteins that are involved in anti-IgM antibody-mediated apoptosis using a subclone of the human Burkitt lymphoma cell line BL60. Apoptosis-associated proteins were detected by high resolution two-dimensional gel electrophoresis on a micropreparative scale. Comparison of the high resolution two-dimensional gel electrophoresis protein patterns from apoptotic and non-apoptotic cells showed differences in approximately 80 spots including protein modifications. Analysis of the predominantly altered proteins was performed by internal Edman microsequencing and/or by peptide mass fingerprinting using matrix-assisted laser desorption/ionization mass spectrometry. Analysis was significantly improved by using new micropreparative high resolution two-dimensional gels employing high protein concentrations. The following 12 apoptosis-associated proteins were identified: heterogeneous nuclear ribonucleoprotein (hnRNP) A1, hnRNP C1/C2, FUSE-binding protein, dUTPase, lymphocyte-specific protein LSP1, UV excision repair protein RAD23 homologue B (HHR23B), 60 S acidic ribosomal protein P0 (L10E), heterochromatin protein 1 homologue alpha (HP1alpha), nucleolin, lamin, neutral calponin, and actin. Fragmentation of actin, hnRNP A1, hnRNP C1/C2, 60 S acidic ribosomal protein P0, lamin, and nucleolin could be inhibited by benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone, a selective irreversible inhibitor of CPP32 (caspase 3).