Notch1 enhances B-cell receptor-induced apoptosis in mature activated B cells without affecting cell cycle

S Romer1, U Saunders, H-M Jäck

  • 1Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger Center, Friedrich-Alexander-University Erlangen-Nürnberg, Glückstrasse 6, 91054 Erlangen, Germany.

The transmembrane receptor Notch1 plays a crucial role in differentiation and apoptosis of hematopoietic cells. To investigate the influence of Notch1 on apoptosis and cell growth of mature murine B cells, we transduced the murine B-lymphoma line NYC 31.1 with a constitutively active, intracellular form of human Notch1 (Notch1-ICT). NYC cells represent mature activated B cells that can be induced to undergo apoptosis by crosslinking of the B-cell receptor (BCR). In contrast to investigations in immature chicken B-cell lines, transduced Notch1-ICT did not affect cell cycle progression, cell growth or surface IgM levels in NYC cells and resulted only in a slight induction of apoptosis. However, BCR-crosslinking enhanced apoptosis, but did not influence cell cycle progression in Notch1-ICT-positive NYC cells. These data imply a distinct function of Notch1 in mature murine B-cells as compared to immature chicken B cells and provide further evidence for Notch1's involvement in B-cell differentiation and development.

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