This is a renewal application to further our investigation into the mechanism and significance of Bif-1-mediated Bax/Bak activation and mitochondrial morphogenesis in the context of tumorigenesis. Our studies have suggested that Bif-1 directly interacts with Bax in the mitochondrial outer membrane (MOM) and that both the physical and functional interactions between Bif-1 and Bax require the priming of monomer Bax by apoptotic stimuli that trigger Bax membrane recruitment, such as the BH3-only protein tBid. It appears that Bif-1 acts by promoting Bax homo-oligomerization rather than by facilitating Bax recruitment to the MOM. In addition, Bak activation is delayed as well in cells lacking Bif-1 during apoptosis. However, Bif-1 does not interact with Bak directly. Interestingly, our preliminary studies have demonstrated that Bif-1 selectively binds to the Bak inhibitor VDAC2. Bif-1, also known as endophilin B1, is a member of the endophilin protein family. Like other endophilins, Bif-1 is able to generate membrane curvature through its N-BAR domain, promoting Bax insertion into lipid bilayers. Moreover, Bif-1 has been shown to be required for fission of the MOM. Thus, we strongly suspect that Bif-1, in collaboration with BH3-only molecules, promotes Bax/Bak activation by altering the mitochondrial membrane shape. Moreover, Bif-1 and endophilin B2 (EndoB2) form stable heterodimers or tetramers in cells, suggesting that EndoB2 may also participate in the MOM remodeling associated with Bax/Bak activation during apoptosis. To further investigate the roles of endophilin B family proteins in Bax/Bak activation and mitochondrial morphogenesis, we propose the following Specific Aims: 1) To define the roles of Bif-1 and EndoB2 in the regulation of Bax/Bak activation, mitochondrial morphogenesis, and apoptosis;2) To determine whether Bif-1 interaction with VDAC2 plays a role in the regulation of Bak oligomerization, mitochondrial morphology, and apoptosis;3) To determine the roles of Bif-1 and EndoB2 in apoptosis, mitochondrial morphogenesis, and androgen-independent prostate cancer progression in mouse models under both physiological and pathological settings.

Public Health Relevance

Accumulating evidence suggests that Bif-1 is a tumor suppressor candidate. Successful implementation of this research will not only gain novel insight into the molecular mechanisms underlying the processes of Bax/Bak activation, mitochondrial morphogenesis and androgen-independent prostate cancer development, but will also contribute to the establishment of new strategies for the prevention and treatment of cancer.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA082197-14
Application #
8450625
Study Section
Special Emphasis Panel (ZRG1-OBT-M (02))
Program Officer
Salnikow, Konstantin
Project Start
1999-08-01
Project End
2016-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
14
Fiscal Year
2013
Total Cost
$234,098
Indirect Cost
$82,578
Name
Pennsylvania State University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Muppidi, Avinash; Doi, Kenichiro; Ramil, Carlo P et al. (2014) Synthesis of cell-permeable stapled BH3 peptide-based Mcl-1 inhibitors containing simple aryl and vinylaryl cross-linkers. Tetrahedron 70:7740-7745
Muppidi, Avinash; Doi, Kenichiro; Edwardraja, Selvakumar et al. (2014) Targeted delivery of ubiquitin-conjugated BH3 peptide-based Mcl-1 inhibitors into cancer cells. Bioconjug Chem 25:424-32
Young, Megan M; Kester, Mark; Wang, Hong-Gang (2013) Sphingolipids: regulators of crosstalk between apoptosis and autophagy. J Lipid Res 54:5-19
Takahashi, Yoshinori; Hori, Tsukasa; Cooper, Timothy K et al. (2013) Bif-1 haploinsufficiency promotes chromosomal instability and accelerates Myc-driven lymphomagenesis via suppression of mitophagy. Blood 121:1622-32
Young, Megan M; Takahashi, Yoshinori; Khan, Osman et al. (2012) Autophagosomal membrane serves as platform for intracellular death-inducing signaling complex (iDISC)-mediated caspase-8 activation and apoptosis. J Biol Chem 287:12455-68
Takahashi, Yoshinori; Meyerkord, Cheryl L; Hori, Tsukasa et al. (2011) Bif-1 regulates Atg9 trafficking by mediating the fission of Golgi membranes during autophagy. Autophagy 7:61-73
Coppola, Domenico; Helm, James; Ghayouri, Msoumeh et al. (2011) Down-regulation of Bax-interacting factor 1 in human pancreatic ductal adenocarcinoma. Pancreas 40:433-7
Yang, Jun; Takahashi, Yoshinori; Cheng, Erdong et al. (2010) GSK-3beta promotes cell survival by modulating Bif-1-dependent autophagy and cell death. J Cell Sci 123:861-70
Lee, Jong Woo; Park, Sungman; Takahashi, Yoshinori et al. (2010) The association of AMPK with ULK1 regulates autophagy. PLoS One 5:e15394
Etxebarria, Aitor; Terrones, Oihana; Yamaguchi, Hirohito et al. (2009) Endophilin B1/Bif-1 stimulates BAX activation independently from its capacity to produce large scale membrane morphological rearrangements. J Biol Chem 284:4200-12

Showing the most recent 10 out of 30 publications