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Mol. Cells 2007; 24(3): 378-387

Published online December 31, 2007

© The Korean Society for Molecular and Cellular Biology

Mitochondrially Targeted Bcl-2 and Bcl-XL Chimeras Elicit Different Apoptotic Responses

Sen Liu, Natasha Ann Pereira, Joong Jiat Teo, Peter Miller, Priya Shah and Zhiwei Song

Abstract

The Bcl-2 family of proteins interacts at the mitochondria to regulate apoptosis. However, the anti-apoptotic Bcl-2 and Bcl-XL are not completely localized to the mitochondria. In an attempt to generate Bcl-2 and Bcl-XL chimeras that are constitutively localized to the mitochondria, we substituted their C-terminal transmembrane tail or both the C-terminal transmembrane tail and the adjacent loop with the equivalent regions from Bak or Bax mutant (BaxS184V) as these regions determine the mitochondrial localization of Bak and Bax. The effects of these substitutions on subcellular localization and their activities were assessed following expression in HeLa and CHO K1 cells. The substitution of the C-terminal tail or the C-terminal tail and the adjacent loop of Bcl-2 with the equivalent regions from Bak or the Bax mutant resulted in its association with the mitochondria. This change in subcellular localization of Bcl-2 chimeras triggered cells to undergo apoptotic-like cell death. The localization of this Bcl-2 chimera to the mitochondria may be associated with the disruption of mitochondrial membrane potential. Unlike Bcl-2, the loop structure adjacent to the C-terminal tail in Bcl-XL is crucial for its localization. To localize the Bcl-XL chimeras to the mitochondria, the loop structure next to the C-terminal tail in Bcl-XL protein must remain intact and cannot be substituted by the loop from Bax or Bak. The chimeric Bcl-XL with both its C-terminal tail and the loop structure replaced by the equivalent regions of Bak or Bax mutant localized throughout the entire cytosol. The Bcl-XL chimeras that are targeted to the mitochondria and the wild type Bcl-XL provided same protection against cell death under several death inducing conditions.

Keywords Apoptosis, Bak, Bax, Bcl-2, Bcl-XL, Chimera

Article

Research Article

Mol. Cells 2007; 24(3): 378-387

Published online December 31, 2007

Copyright © The Korean Society for Molecular and Cellular Biology.

Mitochondrially Targeted Bcl-2 and Bcl-XL Chimeras Elicit Different Apoptotic Responses

Sen Liu, Natasha Ann Pereira, Joong Jiat Teo, Peter Miller, Priya Shah and Zhiwei Song

Abstract

The Bcl-2 family of proteins interacts at the mitochondria to regulate apoptosis. However, the anti-apoptotic Bcl-2 and Bcl-XL are not completely localized to the mitochondria. In an attempt to generate Bcl-2 and Bcl-XL chimeras that are constitutively localized to the mitochondria, we substituted their C-terminal transmembrane tail or both the C-terminal transmembrane tail and the adjacent loop with the equivalent regions from Bak or Bax mutant (BaxS184V) as these regions determine the mitochondrial localization of Bak and Bax. The effects of these substitutions on subcellular localization and their activities were assessed following expression in HeLa and CHO K1 cells. The substitution of the C-terminal tail or the C-terminal tail and the adjacent loop of Bcl-2 with the equivalent regions from Bak or the Bax mutant resulted in its association with the mitochondria. This change in subcellular localization of Bcl-2 chimeras triggered cells to undergo apoptotic-like cell death. The localization of this Bcl-2 chimera to the mitochondria may be associated with the disruption of mitochondrial membrane potential. Unlike Bcl-2, the loop structure adjacent to the C-terminal tail in Bcl-XL is crucial for its localization. To localize the Bcl-XL chimeras to the mitochondria, the loop structure next to the C-terminal tail in Bcl-XL protein must remain intact and cannot be substituted by the loop from Bax or Bak. The chimeric Bcl-XL with both its C-terminal tail and the loop structure replaced by the equivalent regions of Bak or Bax mutant localized throughout the entire cytosol. The Bcl-XL chimeras that are targeted to the mitochondria and the wild type Bcl-XL provided same protection against cell death under several death inducing conditions.

Keywords: Apoptosis, Bak, Bax, Bcl-2, Bcl-XL, Chimera

Mol. Cells
Sep 30, 2021 Vol.44 No.9, pp. 627~698
COVER PICTURE
Non-mitochondrial localization of the N-terminal-deleted mutant form of ACSL1 in Cos7 cells. Green, ACSL1 mutant; Red, mitotracker; Blue, DAPI (Nan et al., pp. 637-646).

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