BCL-2 family proteins are key regulators of apoptosis, a form of programmed cell death essential to normal development and tissue homeostasis. Deregulation of the apoptotic machinery can lead to a host of human diseases characterized by too many or too few cells. Pathologic enforcement of cell survival by anti-apoptotic BCL-2 family proteins, which bind to and inactivate the BAX/BAK initiators of cell death, can lead to the development, maintenance, and chemoresistance of human cancer. In particular, anti-apoptotic BCL-w has been linked to the progression and invasiveness of a broad range of human cancers. BCL-w is believed to migrate from cytosol to mitochondria in response to interaction with BH3-only members of the BCL-2 family, but the physiological triggers and structure-function mechanism of BCL-w translocation are unknown. The Walensky lab has previously employed stapled ?BH3? peptides, which recapitulate the natural structure and function of this critical signaling domain, to identify a novel regulatory site on pro-apoptotic BAX that mediates its mitochondrial translocation and resultant induction of apoptosis. Specifically, BH3 engagement of a groove formed by the juxtaposition of ?-helices 1 and 6 of BAX induces allosteric release of its C-terminal helix for mitochondrial targeting and insertion. I hypothesize that BCL-w, as an anti-apoptotic homologue of BAX, may likewise be subject to regulation of its subcellular distribution. To elucidate the BCL-w translocation mechanism, I aim to: (1) synthesize and characterize stabilized alpha-helix of BCL-2 domains (SAHBs) modeled after BH3 helices to assess their functional interactions with anti-apoptotic BCL-w; (2) locate the binding interface and induced conformational changes associated with BH3-triggered BCL-w translocation; and (3) investigate the physiologic implications of stress-induced BCL-w translocation in cancer. Thus, the overarching goal of my proposal is to characterize the structure-function mechanism for ligand-stimulated BCL- w translocation and determine its contribution to enforcing apoptotic resistance in human cancer. I believe this study could inform a novel therapeutic strategy to disarm BCL-w in cancer by targeted disruption of the binding interface that drives its mitochondrial translocation. I am eager to embark on the rigorous training program proposed for my graduate studies at Harvard Medical School and the Dana-Farber Cancer Institute and look forward to developing as an independent and innovative investigator at the interface of chemical biology, apoptosis research, and cancer medicine.
Chemoresistant cancer cells rely on anti-apoptotic members of the BCL-2 family to bind and block the activated forms of BAX and BAK, which otherwise pierce and destroy the mitochondrial power plants of the cell. BCL-w is an anti-apoptotic protein that has been implicated in cancer and is believed to translocate from cytosol to mitochondria, but the molecular mechanism of translocation and its functional consequences are unknown. I propose to apply chemical, structural, and cellular approaches to characterize the structure-function mechanism of BCL-w translocation, with the goal of informing a new therapeutic strategy to subvert cancer cell survival by disrupting the binding interface that drives the regulated mitochondrial localization of BCL-w.
| Harvey, Edward P; Seo, Hyuk-Soo; Guerra, Rachel M et al. (2018) Crystal Structures of Anti-apoptotic BFL-1 and Its Complex with a Covalent Stapled Peptide Inhibitor. Structure 26:153-160.e4 |
| Guerra, Rachel M; Bird, Gregory H; Harvey, Edward P et al. (2018) Precision Targeting of BFL-1/A1 and an ATM Co-dependency in Human Cancer. Cell Rep 24:3393-3403.e5 |
