Pro-apoptotic activity of mBNIP-21 depends on its BNIP-2 and Cdc42GAP homology (BCH) domain and is enhanced by coxsackievirus B3 infection.
Our previous study reported that mouse BNIP-21 (mBNIP-21) induces apoptosis through a mitochondria-dependent pathway. To map the functional domains of mBNIP-21, we performed mutational analyses and demonstrated that the BNIP-2 and Cdc42GAP homology (BCH) domain is required for apoptosis induction by mBNIP-21 targeting the mitochondria and inducing cytochrome c release. This pro-apoptotic activity was enhanced by coxsackievirus infection. However, deletion of the Bcl-2 homology 3 (BH3)-like domain, a well-known cell 'death domain' in proapoptotic Bcl-2 family proteins, did not affect the activity of mBNIP-21. These data were further supported by transfection of a mouse Bax (mBax) mutant, whose BH3 was replaced by the mBNIP-21 BH3-like domain. This replacement significantly reduced the pro-apoptotic activity of mBax. We also found that the predicted calcium binding domain has no contribution to the mBNIP-21-induced apoptosis. Further mapping of the motifs of BCH domain demonstrated that deletion of the hydrophobic motif proximal to the C-terminal of the BCH significantly reduced its proapoptotic activity. These findings suggest that mBNIP-21, as a member of the BNIP subgroup of the Bcl-2-related proteins, functions without need of BH3 but its BCH domain is critical for its activity in inducing cell elongation, membrane protrusions and apoptotic cell death.
Sall
Alhousseynou
A
Department of Pathology and Laboratory Medicine, University of British Columbia-Providence Heart and Lung Institute, the iCapture Center, St. Paul's Hospital, Vancouver, Canada.
Zhang
Huifang M
HM
Qiu
Dexin
D
Liu
Zhongbin
Z
Yuan
Ji
J
Liu
Zhen
Z
Lim
Travis
T
Ye
Xin
X
Marchant
David
D
McManus
Bruce
B
Yang
Decheng
D
D020816:Amino Acid Motifs; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D029822:Enterovirus B, Human / Q000472:pathogenicity*; D020690:GTPase-Activating Proteins / Q000235:genetics; D006801:Humans; D051379:Mice; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
D051017:Apoptosis Regulatory Proteins; C505158:Arhgap1 protein, mouse; D020690:GTPase-Activating Proteins