TY - JOUR
T1 - The C-terminal transmembrane domain of Bcl-xL mediates changes in mitochondrial morphology
AU - Zheng, Jing Yi
AU - Tsai, Yien Che
AU - Kadimcherla, Pradeep
AU - Zhang, Rong
AU - Shi, Julia
AU - Oyler, George A.
AU - Boustany, Nada N.
N1 - Funding Information:
This work was supported in part by National Institutes of Health grant No. R21RR015264, Biomedical Engineering Research grant No. RG-02-0682 from the Whitaker Foundation, and the Johnson and Johnson Discovery Awards Fund at Rutgers, The State University of New Jersey.
PY - 2008/1/1
Y1 - 2008/1/1
N2 - We investigate the effect of mitochondrial localization and the Bcl-x L C-terminal transmembrane (TM) domain on mitochondrial morphology and subcellular light scattering. CSM 14.1 cell lines stably expressed yellow fluorescent protein (YFP), YFP-Bcl-xL, YFP-Bcl-xL- ΔTM, containing the remainder of Bcl-xL after deletion of the last 21 amino acids corresponding to the TM domain, or YFP-TM, consisting of YFP fused at its C-terminal to the last 21 amino acids of Bcl-xL. YFP-Bcl-xL and YFP-TM localized to the mitochondria. Their expression decreased the intensity ratio of wide-to-narrow angle forward scatter by subcellular organelles, and correlated with an increase in the proportion of mitochondria with an expanded matrix having greatly reduced intracristal spaces as observed by electron microscopy. Cells expressing YFP-TM also exhibited significant autophagy. In contrast, YFP-Bcl-xL-ΔTM was diffusely distributed in the cells, and its expression did not alter light scattering or mitochondrial morphology compared with parental cells. Expression of YFP-Bcl-xL or YFP-Bcl-xL-ΔTM provided significant resistance to staurosporine-induced apoptosis. Surprisingly however, YFP-TM expression also conferred a moderate level of cell death resistance in response to staurosporine. Taken together, our results suggest the existence of a secondary Bcl-xL function that is mediated by the transmembrane domain, alters mitochondrial morphology, and is distinct from BH3 domain sequestration.
AB - We investigate the effect of mitochondrial localization and the Bcl-x L C-terminal transmembrane (TM) domain on mitochondrial morphology and subcellular light scattering. CSM 14.1 cell lines stably expressed yellow fluorescent protein (YFP), YFP-Bcl-xL, YFP-Bcl-xL- ΔTM, containing the remainder of Bcl-xL after deletion of the last 21 amino acids corresponding to the TM domain, or YFP-TM, consisting of YFP fused at its C-terminal to the last 21 amino acids of Bcl-xL. YFP-Bcl-xL and YFP-TM localized to the mitochondria. Their expression decreased the intensity ratio of wide-to-narrow angle forward scatter by subcellular organelles, and correlated with an increase in the proportion of mitochondria with an expanded matrix having greatly reduced intracristal spaces as observed by electron microscopy. Cells expressing YFP-TM also exhibited significant autophagy. In contrast, YFP-Bcl-xL-ΔTM was diffusely distributed in the cells, and its expression did not alter light scattering or mitochondrial morphology compared with parental cells. Expression of YFP-Bcl-xL or YFP-Bcl-xL-ΔTM provided significant resistance to staurosporine-induced apoptosis. Surprisingly however, YFP-TM expression also conferred a moderate level of cell death resistance in response to staurosporine. Taken together, our results suggest the existence of a secondary Bcl-xL function that is mediated by the transmembrane domain, alters mitochondrial morphology, and is distinct from BH3 domain sequestration.
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U2 - 10.1529/biophysj.107.104323
DO - 10.1529/biophysj.107.104323
M3 - Article
C2 - 17766334
AN - SCOPUS:37749008792
SN - 0006-3495
VL - 94
SP - 286
EP - 297
JO - Biophysical Journal
JF - Biophysical Journal
IS - 1
ER -