): Apoptosis or programmed cell death eliminates redundant or damaged cells in multicellular organisms. Abnormal apoptosis contributes to the pathogenesis of many human diseases including cancer. Bcl-2 and related proteins function as either suppressors or promoters of apoptosis. Aberrant expression of them leads to dysregulation of apoptosis and to the onset of apoptotic diseases. Bcl-2 is anchored on the membrane of the mitochondrion, the endoplasmic reticulum (ER) or the nucleus via its C-terminal transmembrane sequence. Bcl-2 maintains the normal function of the membranes in many apoptotic events, protecting the organelles and hence the cells. The structure of the cytosolic domain of Bcl-XL, a Bcl-2 homolog, is strikingly similar to the pore-forming domains of bacterial toxins. Though several Bcl-2 family members form pores in synthetic bilayers, we do not know whether they form pores in the native membrane and if they do, how their pore-forming activities contribute to the regulation of membrane permeability and apoptosis. Our long-term goal is to understand the molecular mechanisms by which Bcl-2 regulates apoptosis. Our short-term goal is to determine the functional, native Bcl-2 structure at and in the organelle membrane. We generated a series of fluorescent, full-length Bcl-2 proteins that each had a single dye attached at a specific site. The dye-labeled Bcl-2 proteins form pores and change spectra upon insertion into membranes. Hence the Bcl-2-membrane interaction can be detected and analyzed spectroscopically. Using the active, site-specifically labeled fluorescent Bcl-2 and a combination of fluorescence spectroscopic methods, we aim to characterize the structure of Bcl-2 at the ER microsomes and the mitochondria with focus on its transmembrane domain, pore and cytosolic domain. The results of the project will establish a structural basis for understanding the functions of Bcl-2 in regulating both membrane permeability and apoptosis, which is a prerequisite for designing therapeutic approaches to control Bcl-2 activity, to treat and perhaps to cure apoptotic diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM062964-05
Application #
6874883
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Chin, Jean
Project Start
2001-04-01
Project End
2007-03-31
Budget Start
2005-04-01
Budget End
2007-03-31
Support Year
5
Fiscal Year
2005
Total Cost
$213,400
Indirect Cost
Name
University of Oklahoma Health Sciences Center
Department
Biochemistry
Type
Schools of Medicine
DUNS #
878648294
City
Oklahoma City
State
OK
Country
United States
Zip Code
73117
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Zhang, Zhi; Subramaniam, Sabareesh; Kale, Justin et al. (2016) BH3-in-groove dimerization initiates and helix 9 dimerization expands Bax pore assembly in membranes. EMBO J 35:208-36
Ding, Jingzhen; Mooers, Blaine H M; Zhang, Zhi et al. (2014) After embedding in membranes antiapoptotic Bcl-XL protein binds both Bcl-2 homology region 3 and helix 1 of proapoptotic Bax protein to inhibit apoptotic mitochondrial permeabilization. J Biol Chem 289:11873-96
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Peng, Jun; Ding, Jingzhen; Tan, Chibing et al. (2009) Oligomerization of membrane-bound Bcl-2 is involved in its pore formation induced by tBid. Apoptosis 14:1145-53

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