Mono- or Double-Site Phosphorylation Distinctly Regulates the Proapoptotic Function of Bax
Abstract
Bax is the major multidomain proapoptotic molecule that is required for apoptosis.
It has been reported that phosphorylation of Bax at serine(S) 163 or S184 activates
or inactivates its proapoptotic function, respectively. To uncover the mechanism(s)
by which phosphorylation regulates the proapoptotic function of Bax, a series of serine
(S)-> alanine/glutamate (A/E) Bax mutants, including S163A, S184A, S163E, S184E, S163E/S184A
(EA), S163A/S184E (AE), S163A/S184A (AA) and S163E/S184E (EE), were created to abrogate
or mimic, respectively, either single or double-site phosphorylation. The compound
Bax mutants (i.e. EA and AE) can flesh out the functional contribution of individual
phosphorylation site(s). WT and each of these Bax mutants were overexpressed in Bax(-/-)
MEF or lung cancer H157 cells and the proapoptotic activities were compared. Intriguingly,
expression of any of Bax mutants containing the mutation S -> A at S184 (i.e. S184A,
EA or AA) represents more potent proapoptotic activity as compared to WT Bax in association
with increased 6A7 epitope conformational change, mitochondrial localization/insertion
and prolonged half-life. In contrast, all Bax mutants containing the mutation S ->
E at S184 (i.e. S184E, AE or EE) have a mobility-shift and fail to insert into mitochondrial
membranes with decreased protein stability and less apoptotic activity. Unexpectedly,
mutation either S -> A or S -> E at S163 site does not significantly affect the proapoptotic
activity of Bax. These findings indicate that S184 but not S163 is the major phosphorylation
site for functional regulation of Bax's activity. Therefore, manipulation of the phosphorylation
status of Bax at S184 may represent a novel strategy for cancer treatment.
Type
Other articleSubject
mitochondrial-membrane permeabilizationcytochrome-c release
bcl-x-l
cell-death
conformational-change
bh3 domains
apoptosis
protein
activation
survival
biology
multidisciplinary sciences
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https://hdl.handle.net/10161/4578Published Version (Please cite this version)
10.1371/journal.pone.0013393Citation
Wang,Qinhong;Sun,Shi-Yong;Khuri,Fadlo;Curran,Walter J.;Deng,Xingming. 2010. Mono-
or Double-Site Phosphorylation Distinctly Regulates the Proapoptotic Function of Bax.
Plos One 5(10): e13393-e13393.
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