A putative role for human BFK in DNA damage-induced apoptosis.
Human BFK (BCL-2 family kin) is a novel pro-apoptotic BCL-2 family member specifically expressed in the gastrointestinal tract. BFK has the characteristic BH3 domain, which was shown to be essential for the apoptosis-inducing activity of pro-apoptotic BCL-2 family members. When overexpressed, BFK interacts with BCL-XL and BCL-W but not BCL-2 or BAD in co-immunoprecipitations studies. We find that BFK exhibits striking similarity to BID in the way it is activated through cleavage during apoptosis. The endogenous and cleaved versions of BFK are readily recognized by the rabbit and mouse sera raised against human BFK. An ideal caspase 3 or 7 target sequence, DEVD (amino acids 38-41), is evident N-terminal to the BH3 domain. A recombinant version of the protein containing all residues downstream of the putative caspase cleavage site induces apoptosis in human colon cancer cells, HCT116, and in wild-type mouse embryonic fibroblasts (MEFs), which can be reversed by co-expression of BCL-XL or BCL-W. BFK becomes activated through caspase-dependent cleavage during DNA damage-induced apoptosis. The cleaved form of the protein is dependent on the presence of BAX or BAK for its ability to induce apoptosis, since BAX(-/-)-BAK(-/-) double-knockout MEFs are completely resistant to BFK-induced apoptosis.
Ozören
Nesrin
N
Department of Molecular Biology and Genetics, Apoptosis and Cancer Immunology Laboratory (AKIL), Boğaziçi University, Istanbul, Turkey. nesrin.ozoren@boun.edu.tr
Inohara
Naohiro
N
Núñez
Gabriel
G
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D003106:Colon / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism; D004249:DNA Damage; D045325:HCT116 Cells; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011817:Rabbits; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051025:bcl-Associated Death Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; C494819:BAD protein, human; C494772:BAK1 protein, human; C494826:BAX protein, human; C494811:BCL2L1 protein, human; C481505:BCL2L15 protein, human; C491073:BCL2L2 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein