Phosphorylation status modulates Bcl-2 function during glucocorticoid-induced apoptosis in T lymphocytes.
Glucocorticoids are known to induce apoptosis in lymphoid cells, and Bcl-2 overexpression can block the apoptosis-inducing action of glucocorticoids. Since phosphorylation of Bcl-2 is implicated in regulating Bcl-2 function, we considered the role of Bcl-2 phosphorylation in protecting lymphoid cells from glucocorticoid-induced cell death. Five stably transfected cell lines of WEHI 7.1 cells expressing either wild-type Bcl-2 or alanine mutants of Bcl-2 at amino acids threonine 56, serine 70, threonine 74, or serine 87 were created. Expression of the mutant Bcl-2 proteins was documented by flow cytometry and Western blot analysis. Mutation of Bcl-2 on T56 and S87 eliminated the ability of Bcl-2 to inhibit glucocorticoid-induced cell shrinkage, mitochondrial depolarization, DNA fragmentation, and cell death. Mutation of T74 only partially impaired the ability of Bcl-2 to block glucocorticoid-induced apoptosis whereas mutation of S70 in Bcl-2 did not alter its ability to block glucocorticoid-induced apoptosis.
Huang
Se-Te J
ST
The Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA.
Cidlowski
John A
JA
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D005434:Flow Cytometry; D015870:Gene Expression; D005838:Genotype; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009154:Mutation; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D005938:Glucocorticoids; D019253:Proto-Oncogene Proteins c-bcl-2; D003907:Dexamethasone