title: Targeting Bcl-2 based on the interaction of its BH4 domain with the inositol 1,4,5-trisphosphate receptor.
abstract: Bcl-2 is the founding member of a large family of apoptosis regulating proteins. Bcl-2 is a prime target for novel therapeutics because it is elevated in many forms of cancer and contributes to cancer progression and therapy resistance based on its ability to inhibit apoptosis. Bcl-2 interacts with proapoptotic members of the Bcl-2 family to inhibit apoptosis and small molecules that disrupt this interaction have already entered the cancer therapy arena. A separate function of Bcl-2 is to inhibit Ca2+ signals that promote apoptosis. This function is mediated through interaction of the Bcl-2 BH4 domain with the inositol 1,4,5-trisphosphate receptor (IP3R) Ca2+ channel. A novel peptide inhibitor of this interaction enhances proapoptotic Ca2+ signals. In preliminary experiments this peptide enhanced ABT-737 induced apoptosis in chronic lymphocytic leukemia cells. These findings draw attention to the BH4 domain as a potential therapeutic target. This review summarizes what is currently known about the BH4 domain of Bcl-2, its interaction with the IP3R and other proteins, and the part it plays in Bcl-2's anti-apoptotic function. In addition, we speculate on how the BH4 domain of Bcl-2 can be targeted therapeutically not only for diseases associated with apoptosis resistance, but also for diseases associated with accelerated cell death.
authors.affiliation: Department of Medicine, Comprehensive Cancer Center and University Hospital of Cleveland, Case Western Reserve University, Cleveland, OH 44106, USA. Yiping.Rong@case.edu
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Rong
authors.forename: Paul
authors.initials: P
authors.lastname: Barr
authors.forename: Vivien C
authors.initials: VC
authors.lastname: Yee
authors.forename: Clark W
authors.initials: CW
authors.lastname: Distelhorst
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D045744:Cell Line, Tumor; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein