The early region 4 orf4 protein of human adenovirus type 5 induces p53-independent cell death by apoptosis.
نویسندگان
چکیده
Previous studies by our group showed that infection of human and rodent cells by human adenovirus type 5 (Ad5) results in the induction of p53-independent apoptosis and cell death that are dependent upon transactivation of early region 4 (E4). To identify which E4 products are involved, studies were conducted with p53-deficient human SAOS-2 cells infected with various Ad5 E4 mutants. An E4orf6-deficient mutant was defective in cell killing, whereas another that expressed only E4orf6 and E4orf4 killed like wild-type virus, suggesting that E4orf6 may be responsible for cytotoxicity; however, a mutant expressing only E4orf4 induced high levels of cell death, indicating that this E4 product may also be able to induce cytotoxicity. To define the E4 cell death-inducing functions more precisely, cDNAs encoding individual E4 products were introduced into cells by DNA transfection in the absence of other Ad5 proteins. In cotransfections with a cDNA encoding firefly luciferase, enzymatic activity was high in all cases except with E4orf4, where luciferase levels were less than 20% of those in controls. In addition, drug selection of several cell types following transfection with retroviral vector DNA encoding individual E4 products as well as puromycin resistance yielded a large number of cell colonies except when E4orf4 was expressed. These data demonstrated that E4orf4 is the only E4 product capable of independent cell killing. Cell death induced by E4orf4 was due to apoptosis, as evidenced by 4',6-diamidino-2-phenylindole (DAPI) staining of cell nuclei in E4orf4-expressing cells. Thus, although E4orf6 may play some role, these results suggested that E4orf4 may be the major E4 product responsible for induction of p53-independent apoptosis.
منابع مشابه
Adenovirus type 5 early region 4 is responsible for E1A-induced p53-independent apoptosis.
In the absence of E1B, the 289- and 243-residue E1A products of human adenovirus type 5 induce p53-dependent apoptosis. However, our group has shown recently that the 289-residue E1A protein is also able to induce apoptosis by a p53-independent mechanism (J. G. Teodoro, G. C. Shore, and P. E. Branton, Oncogene 11:467-474, 1995). Preliminary results suggested that p53-independent cell death requ...
متن کاملالقای آپوپتوز وابسته به p53 در ردهی سلولی لوسمی لنفوبلاستیک حاد پیشساز لنفوسیت B (NALM-6) توسط مولکول کوچک RITA
Background and Objective: The use of low-molecular-weight, nonpeptidic molecules that degrade the interaction between the p53 protein and its negative regulator MDM2 (Murine- double minute colon 2) is a new therapeutic strategy for treatment of various types of cancer. One of these agents is RITA (reactivation of p53 and induction of tumor cell apoptosis) which binds to p53 protein and inhibits...
متن کاملAdenovirus type 5 E4 open reading frame 4 protein induces apoptosis in transformed cells.
Adenovirus type 5 E4 open reading frame 4 (E4orf4) protein has been previously shown to counteract transactivation of the junB and c-fos genes by cyclic AMP plus E1A protein and to interact with protein phosphatase 2A (PP2A). Here, we show that the wild-type E4orf4 protein induces apoptosis in the E1A-expressing 293 cells, in NIH 3T3 cells transformed with v-Ras, and in the lung carcinoma cell ...
متن کاملExpression of p53 in Saos-2 osteosarcoma cells induces apoptosis which can be inhibited by Bcl-2 or the adenovirus E1B-55 kDa protein.
Studies were carried out to determine the effects of introducing p53 using an adenovirus gene transfer vector into p53 null human Saos-2 osteogenic carcinoma cells. Expression of p53 led to cell death within 30-40 h. The morphology of these cells as determined by electron microscopy indicated that death was by apoptosis. Such death was significantly reduced in Saos-2 variants that express high ...
متن کاملE4orf4, a Novel Adenovirus Death Factor That Induces p53-independent Apoptosis by a Pathway That Is Not Inhibited by zVAD-fmk
In the absence of E1B, the 289-amino acid product of human adenovirus type 5 13S E1A induces p53-independent apoptosis by a mechanism that requires viral E4 gene products (Marcellus, R.C., J.C. Teodoro, T. Wu, D.E. Brough, G. Ketner, G.C. Shore, and P.E. Branton. 1996. J. Virol. 70:6207-6215) and involves a mechanism that includes activation of caspases (Boulakia, C.A., G. Chen, F.W. Ng, J. G. ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of virology
دوره 72 9 شماره
صفحات -
تاریخ انتشار 1998