The impact of the apoptotic pathways on cancer biology is broad because the BCL-2 family of proteins regulates nearly all steps of tumor progression, exhibits prognostic value, and can be predictive of treatment success. In the clinic, tumor cells die in response to chemotherapeutics and radiation treatment by inducing apoptosis, which has generated substantial enthusiasm for dissecting how this pathway proceeds and may be pharmacologically modulated. Apoptosis proceeds when the BCL-2 family of proteins promotes mitochondrial outer membrane permeabilization (MOMP), which triggers the release of pro-apoptotic molecules from mitochondria into the cytoplasm. Two BCL-2 family proteins, BAK and BAX, directly engage MOMP by creating proteolipid pores in the outer mitochondrial membrane. BAK/BAX-dependent MOMP is required for apoptosis, and is initiated by a BCL-2 family subset, the BH3-only proteins, e.g., BID. Our studies recently discovered that in order for BAK/BAX and BID to induce MOMP, mitochondria must functionally intersect with the sphingolipid pathway. The novel hypothesis is that mitochondrial sphingolipids confer function to the BCL-2 family, which may explain how BAK/BAX and BID specifically target mitochondria. Curiosity in the BCL-2 family-mitochondrial interactions mentioned above led to the identification that the sphingolipid pathway plays a crucial role in BCL-2 family function. We recently identified that two products within the sphingolipid pathway, sphingosine-1-PO4 and hexadecenal, directly regulate BAK and BAX activation, respectively. The goals of the current application are focused on understanding the mechanistic contribution of sphingosine-1-PO4 and hexadecenal on BCL-2 family function, MOMP and apoptosis. This project emerged following years of effort to identify cellular components necessary for MOMP, and we propose three specific aims: (1) to explore the biochemical requirements for the sphingolipid pathway on BID-induced BAK/BAX activation, (2) to elucidate the functional cooperation between BAK/BAX and the sphingolipid pathway in the contexts of cellular fate and tumorigenesis, and (3) to probe the structural relationships between BAX and hexadecenal necessary to promote MOMP and apoptosis. The scientific outcome of this proposal will uncover novel mechanisms of BCL-2 family regulation and commitment to apoptosis. These data will elucidate the functional and structural interaction(s) between BAK/BAX and the sphingolipids, and serve as the foundation for the development of BAK/BAX pharmacologic regulators in the future.

Public Health Relevance

Cancer occurs when cells acquire changes that convert them from a normal to malignant state. Apoptosis is a program of cellular suicide that eliminates damaged cells to prevent cancer;yet the body also turns on this program following chemotherapy and radiation treatments in order to kill cancer cells. Therefore, it is important to investigate the pathways that control apoptosis to understand how cancer occurs and should be treated.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA157740-02
Application #
8268982
Study Section
Cellular Signaling and Regulatory Systems Study Section (CSRS)
Program Officer
Salnikow, Konstantin
Project Start
2011-06-01
Project End
2016-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
2
Fiscal Year
2012
Total Cost
$350,384
Indirect Cost
$142,884
Name
Icahn School of Medicine at Mount Sinai
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
Serasinghe, Madhavika N; Gelles, Jesse D; Li, Kent et al. (2018) Dual suppression of inner and outer mitochondrial membrane functions augments apoptotic responses to oncogenic MAPK inhibition. Cell Death Dis 9:29
Trotta, Andrew Paul; Chipuk, Jerry Edward (2017) Mitochondrial dynamics as regulators of cancer biology. Cell Mol Life Sci 74:1999-2017
Chipuk, Jerry Edward; Luna-Vargas, Mark P A (2017) The peroxisomes strike BAK: Regulation of peroxisome integrity by the Bcl-2 family. J Cell Biol 216:547-549
Trotta, Andrew P; Gelles, Jesse D; Serasinghe, Madhavika N et al. (2017) Disruption of mitochondrial electron transport chain function potentiates the pro-apoptotic effects of MAPK inhibition. J Biol Chem 292:11727-11739
Renault, Thibaud T; Luna-Vargas, Mark P A; Chipuk, Jerry E (2016) Mouse Liver Mitochondria Isolation, Size Fractionation, and Real-time MOMP Measurement. Bio Protoc 6:
Luna-Vargas, Mark P A; Chipuk, Jerry E (2016) The deadly landscape of pro-apoptotic BCL-2 proteins in the outer mitochondrial membrane. FEBS J 283:2676-89
Gelles, Jesse D; Chipuk, Jerry Edward (2016) Robust high-throughput kinetic analysis of apoptosis with real-time high-content live-cell imaging. Cell Death Dis 7:e2493
Luna-Vargas, Mark P A; Chipuk, Jerry Edward (2016) Physiological and Pharmacological Control of BAK, BAX, and Beyond. Trends Cell Biol 26:906-917
Gelles, J D; Elkholi, R; Serasinghe, M N et al. (2016) From zero to sixty: cell death signaling in the city that never sleeps. Oncogene 35:1457-60
Serasinghe, Madhavika N; Wieder, Shira Y; Renault, Thibaud T et al. (2015) Mitochondrial division is requisite to RAS-induced transformation and targeted by oncogenic MAPK pathway inhibitors. Mol Cell 57:521-36

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