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- Title
Phosphorylation of BCL-2 regulates ER Ca<sup>2+</sup> homeostasis and apoptosis.
- Authors
Bassik, Michael C.; Scorrano, Luca; Oakes, Scott A.; Pozzan, Tullio; Korsmeyer, Stanley J.
- Abstract
Phosphorylation of BCL-2 within an unstructured loop inhibits its antiapoptotic effect. We found that phosphorylated BCL-2 predominantly localized to the endoplasmic reticulum (ER) and tested whether phosphorylation would control its activity at this organelle, where Ca2+ dynamics serve as a critical control point for apoptosis. Phosphorylation greatly inhibits the ability of BCL-2 to lower [Ca2+]er and protect against Ca2+-dependent death stimuli. Cells expressing nonphosphorylatable BCL-2AAA exhibited increased leak of Ca2+ from the ER and further diminished steady-state [Ca2+]er stores when compared to cells expressing BCL-2wt. Consequently, when BCL-2 is phosphorylated, Ca2+ discharge from the ER is increased, with a secondary increase in mitochondrial Ca2+ uptake. We also demonstrate that phosphorylation of BCL-2 inhibits its binding to proapoptotic family members. This inhibitory mechanism manifested at the ER, where phosphorylated BCL-2 was unable to bind proapoptotic members. [Ca2+]er proved coordinate with the capacity of BCL-2 to bind proapoptotic BH3-only members, further integrating the apoptotic pathway and Ca2+ modulation. Unexpectedly, the regulation of ER Ca2+ dynamics is a principal avenue whereby BCL-2 phosphorylation alters susceptibility to apoptosis.
- Publication
EMBO Journal, 2004, Vol 23, Issue 5, p1207
- ISSN
0261-4189
- Publication type
Academic Journal
- DOI
10.1038/sj.emboj.7600104