TNFalpha signaling in the pro B cell line FL5.12 results in mitochondrial depolarization and cell death that can only be blocked synergistically by Bcl-xL and the caspase inhibitor ZVAD-fmk. Preliminary data show that vector control FL5.12 Neo undergo a loss of the mitochondrial transmembrane potential in the presence and absence of ZVAD-fmk during TNFalpha induced apoptosis. FL5.12 Bcl-xL can also experience a loss of the mitochondrial transmembrane potential when downstream caspases are activated during TNFalpha induced programmed cell death but not when they are inhibited by ZVAD-fmk. Cyclosporin A (CsA) can block mitochondrial depolarization and in the presence of caspase inhibitors can block TNFalpha induced cell death. We propose that mitochondrial depolarization in TNFalpha induced apoptosis proceeds through two mechanisms. One is caspase dependent and Bcl-xL and CsA insensitive and the other is caspase independent and Bcl-xL and CsA inhibitable. The proposed experiments are designed to determine whether blocking mitochondria) depolarization is required in order to prevent cell death and to determine how Bcl-xL maintains deltapsim. Finally, we will determine the targets of activated caspases that result in mitochondria) depolarization.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31GM020435-03
Application #
6385143
Study Section
Special Emphasis Panel (ZRG1-ALTX-4 (03))
Program Officer
Toliver, Adolphus
Project Start
2001-09-27
Project End
Budget Start
2001-09-27
Budget End
2002-09-26
Support Year
3
Fiscal Year
2001
Total Cost
$22,344
Indirect Cost
Name
University of Miami School of Medicine
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
City
Miami
State
FL
Country
United States
Zip Code
33146
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Johnson, B W; Cepero, E; Boise, L H (2000) Bcl-xL inhibits cytochrome c release but not mitochondrial depolarization during the activation of multiple death pathways by tumor necrosis factor-alpha. J Biol Chem 275:31546-53