International Immunology, Vol. 11, No. 11, 1753-1761,
November 1999
© 1999 Japanese Society for Immunology
Expression of the Bcl-2 family member A1 is developmentally regulated in T cells
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6082, USA
1 Department of Biology, Haverford College, Haverford, PA 19041, USA
2 Fox Chase Cancer Center, Philadelphia, PA 19111, USA
Correspondence to: M. P. Cancro
During T cell development, cells that fail to meet stringent selection criteria undergo programmed cell death. Thymocyte and peripheral T cell susceptibility to apoptosis is influenced by expression of Bcl-2 family members, some of which are expressed in a developmentally patterned manner. We previously showed developmentally regulated expression of A1, an anti-apoptotic Bcl-2 family member, among B cell developmental subsets. Here we show that cells of the T lineage also express A1 in a developmentally regulated manner. Both A1 mRNA and A1 protein are readily detectable in the thymus, and while present among DN cells, A1 mRNA is up-regulated to very high levels among double-positive (DP) thymocytes. It is then down-regulated to moderate levels among single-positive (SP) thymocytes, and finally expressed at ~25-fold lower levels among mature SP CD4+ and CD8+ lymph node T cells than among DP thymocytes. Furthermore, we find that in vitro TCR ligation up-regulates A1 expression among both DP and SP thymocytes. Together, these data show that A1 expression is developmentally regulated in T lymphocytes and is responsive to TCR signaling, suggesting that A1 may play a role in maintaining the viability of DP thymocytes.
Keywords: apoptosis, FACS, gene regulation, maturation, molecular biology, mouse, T lymphocytes
Transmitting editor: A. Singer
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