Induction and endoplasmic reticulum location of BIK/NBK in response to apoptotic signaling by E1A and p53.
A DNA microarray analysis identified the BH3-only BCL-2 family member, BIK/NBK, as a transcript that is upregulated during induction of apoptosis by oncogenic E1A. E1A depended on wild-type p53 to induce BIK and activate the death program. Further, p53 independently induced BIK RNA and protein, and BIK alone stimulated cell death in p53-null cells, dependent on the activation of caspases. BIK function, however, was abrogated by a disabling point mutation within the BH3 domain. Collectively, these results argue that BIK is a downstream apoptotic effector of p53 in response to a physiological p53-mediated death stimulus provided by E1A. Elevated BCL-2 functioned downstream of p53 and BIK induction to inhibit the E1A death pathway, with the ratio of anti-apoptotic BCL-2 and pro-apoptotic BIK determining cell death or survival in E1A-expressing cells. Cells expressing BCL-2 or treated with the pan caspase inhibitor, zVAD-fmk, allowed accumulation of high levels of cytotoxic BIK compared to control cells. Of note, a significant fraction of either ectopic or endogenous BIK was found associated with the endoplasmic reticulum, suggesting that this organelle, in addition to mitochondria, may be a target of BIK function.
Mathai
Jaigi P
JP
Department of Biochemistry, McIntyre Medical Sciences Building, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada H3G 1Y6.
Germain
Marc
M
Marcellus
Richard C
RC
Shore
Gordon C
GC
D000256:Adenoviridae / Q000235:genetics; D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000494:pharmacology*; D000595:Amino Acid Sequence; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D020169:Caspases / Q000502:physiology; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000737:chemistry*; D004847:Epithelial Cells / Q000378:metabolism; D020869:Gene Expression Profiling; D005822:Genetic Vectors; D006801:Humans; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D014176:Protein Biosynthesis; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*
D017500:Adenovirus E1A Proteins; D051017:Apoptosis Regulatory Proteins; C096820:BIK protein, human; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D020169:Caspases