Identification of Apoptosis-associated Proteins in a Human Burkitt Lymphoma Cell Line

Abstract

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 an- tibody-mediated apoptosis using a subclone of the hu- man Burkitt lymphoma cell line BL60. Apoptosis-associ- ated proteins were detected by high resolution two- dimensional gel electrophoresis on a micropreparative scale. Comparison of the high resolution two-dimen- sional gel electrophoresis protein patterns from apop- totic and non-apoptotic cells showed differences in ?80 spots including protein modifications. Analysis of the predominantly altered proteins was performed by inter- nal Edman microsequencing and/or by peptide mass fin- gerprinting using matrix-assisted laser desorption/ioni- zation mass spectrometry. Analysis was significantly improved by using new micropreparative high resolu- tion two-dimensional gels employing high protein con- centrations. The following 12 apoptosis-associated proteins were identified: heterogeneous nuclear ribo- nucleoprotein (hnRNP) A1, hnRNP C1/C2, FUSE-bind- ing protein, dUTPase, lymphocyte-specific protein LSP1, UV excision repair protein RAD23 homologue B (HHR23B), 60 S acidic ribosomal protein P0 (L10E), het- erochromatin protein 1 homologue ? (HP1 ), 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)