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The p53 tumor suppressor gene is critically involved in cell cycle regulation, DNA repair, and programmed cell death. Several lines of evidence suggest that p53 death signals lead to caspase activation; however, the mechanism of caspase activation by p53 still is unclear. Expressing wild type p53 by means of an adenoviral expression vector, we were able to induce apoptotic cell death, as characterized by morphological changes, phosphatidylserine externalization, and internucleosomal DNA fragmentation, in p53null Saos-2 cells. This cell death was accompanied by caspase activation as well as by cleavage of caspase substrates and was preceded by mitochondrial cytochrome c release. The addition of the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD-fmk) directly after transduction almost completely prevented p53-induced apoptotic cell death but did not inhibit mitochondrial cytochrome crelease. In contrast, N-acetylcysteine, even at high concentrations, could not prevent induction of programmed cell death by p53 expression. Cytosolic extracts from Saos-2 cells transduced with p53, but not from Saos-2 cells transduced with the empty adenoviral vector, contained a cytochrome c-releasing activityin vitro, which was still active in the presence of zVAD-fmk. When Bax was immunodepleted from the cytosolic extracts of p53-expressing cells before incubation with isolated mitochondria, thein vitro cytochrome c release was abolished. Thus, we could demonstrate in cells and in vitro that p53 activates the apoptotic machinery through induction of the release of cytochrome c from the mitochondrial intermembrane space. Furthermore, we provide in vitro evidence for the requirement of cytosolic Bax for this cytochromec-releasing activity of p53 in Saos-2 cells. The p53 tumor suppressor gene is critically involved in cell cycle regulation, DNA repair, and programmed cell death. Several lines of evidence suggest that p53 death signals lead to caspase activation; however, the mechanism of caspase activation by p53 still is unclear. Expressing wild type p53 by means of an adenoviral expression vector, we were able to induce apoptotic cell death, as characterized by morphological changes, phosphatidylserine externalization, and internucleosomal DNA fragmentation, in p53null Saos-2 cells. This cell death was accompanied by caspase activation as well as by cleavage of caspase substrates and was preceded by mitochondrial cytochrome c release. The addition of the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD-fmk) directly after transduction almost completely prevented p53-induced apoptotic cell death but did not inhibit mitochondrial cytochrome crelease. In contrast, N-acetylcysteine, even at high concentrations, could not prevent induction of programmed cell death by p53 expression. Cytosolic extracts from Saos-2 cells transduced with p53, but not from Saos-2 cells transduced with the empty adenoviral vector, contained a cytochrome c-releasing activityin vitro, which was still active in the presence of zVAD-fmk. When Bax was immunodepleted from the cytosolic extracts of p53-expressing cells before incubation with isolated mitochondria, thein vitro cytochrome c release was abolished. Thus, we could demonstrate in cells and in vitro that p53 activates the apoptotic machinery through induction of the release of cytochrome c from the mitochondrial intermembrane space. Furthermore, we provide in vitro evidence for the requirement of cytosolic Bax for this cytochromec-releasing activity of p53 in Saos-2 cells. wild type benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone benzyloxycarbonyl-Asp-Glu-Val-Asp aminofluoromethylcoumarin propidium iodide The p53 tumor suppressor gene is the central integrator of the cellular response to DNA damage, oncogenic transformation, and growth factor withdrawal (1.Levine A.J. Cell. 1997; 88: 323-331Abstract Full Text Full Text PDF PubMed Scopus (6759) Google Scholar). The cell cycle regulatory and the DNA repair functions of p53 are largely executed by transactivation of p53-response genes such as p21/WAF1/CIP1 (2.El-Deiry W.S. Tokino T. Velculescu V.E. Levy D.B. Parsons R. Trent J.M. Lin D. Mercer W.E. Kinzler K. Vogelstein B. Cell. 1993; 75: 817-825Abstract Full Text PDF PubMed Scopus (7957) Google Scholar, 3.Harper J.W. Adami G.R. Wei N. Keyomarsi K. Elledge S.J. Cell. 1993; 75: 805-816Abstract Full Text PDF PubMed Scopus (5250) Google Scholar, 4.Xiong Y. Hannon G.J. Zhang H. Casso D. Kobayashi R. Beach D. Nature. 1993; 366: 701-704Crossref PubMed Scopus (3179) Google Scholar, 5.Bunz F. Dutriaux A. Lengeauer C. Waldman T. Zhou S. Brown J.P. Sedivy J.M. Kinzler K.W. Vogelstein B. Science. 1998; 282: 1497-1501Crossref PubMed Scopus (2549) Google Scholar) or GADD45 (6.Kastan M.B. Zhan Q. El-Deiry W.S. Carrier F. Jacks T. Walsh W.V. Plunkett B.S. Vogelstein B. Fornace Jr., A.J. Cell. 1992; 71: 587-597Abstract Full Text PDF PubMed Scopus (2931) Google Scholar), thus relying on the ability of p53 to act as a sequence-specific transcription factor. In contrast, the tumor-suppressing activity of p53 does not depend on its transactivational function (7.Crook T. Marston N.J. Sara E.A. Vousden K.H. Cell. 1994; 79: 817-827Abstract Full Text PDF PubMed Scopus (224) Google Scholar, 8.Unger T. Mietz J.A. Scheffner M. Yee C.L. Howley P.M. Mol. Cell. Biol. 1993; 13: 5186-5194Crossref PubMed Scopus (129) Google Scholar, 9.Zhang Q. Funk W.D. Wright W.E. Shay J.W. Deisseroth A.B. EMBO J. 1994; 13: 2535-2544Crossref PubMed Scopus (125) Google Scholar, 10.Rowan S. Ludwig R.L. Haupt Y. Bates S. Lu X. Oren M. Vousden K.H. EMBO J. 1996; 15: 827-838Crossref PubMed Scopus (294) Google Scholar). It has been shown in several cell types that wild type (wt)1 p53 is required for the apoptotic cell death as induced by γ-irradiation or a variety of anticancer drugs (11.Lowe S.W. Ruley H.E. Jacks T. Housman D.E. Cell. 1993; 74: 957-967Abstract Full Text PDF PubMed Scopus (2963) Google Scholar, 12.Lowe S.W. Schmitt E.M. Smith S.W. Osborne B.A. Jacks T. Nature. 1993; 362: 847-849Crossref PubMed Scopus (2767) Google Scholar). Yet, the pathways whereby p53 leads to execution of the apoptosis program are not well characterized. Possible mechanisms include transcriptional activation of the proapoptotic Bcl-2 family member Bax (13.Miyashita T. Reed J.C. Cell. 1995; 80: 293-299Abstract Full Text PDF PubMed Scopus (305) Google Scholar, 14.Yin C. Knudson C.M. Korsmeyer S.J. Van Dyke T. Nature. 1997; 385: 637-640Crossref PubMed Scopus (595) Google Scholar), the generation of reactive oxygen species (15.Polyak K. Xia Y. Zweier J.L. Kinzler K.W. Vogelstein B. Nature. 1997; 389: 300-305Crossref PubMed Scopus (2246) Google Scholar), and transcriptional up-regulation of death receptors such as CD95/Fas/APO-1 or DR5/KILLER (16.Owen-Schaub L.B. Zhang W. Cusack J.C. Angelo L.S. Santee S.M. Fujiwara T. Roth J.A. Deisseroth A.B. Zhang W.W. Kruzel E. et al.Mol. Cell. Biol. 1995; 15: 3032-3040Crossref PubMed Scopus (690) Google Scholar, 17.Bennett M. MacDonald K. Chan S.-W. Luzio J.P. Simari R. Weissberg P. Science. 1998; 282: 290-293Crossref PubMed Scopus (654) Google Scholar, 18.Müller M. Wilder S. Bannasch D. Israeli D. Lehlbach K. Li-Weber M. Friedman S.L. Galle P.R. Oren M. Krammer P.H. J. Exp. Med. 1998; 188: 2033-2045Crossref PubMed Scopus (735) Google Scholar, 19.Sheikh M.S. Burns T.F. Huang Y. Wu G.S. Amundson S. Brooks K.S. Fornace Jr., A.J. El-Deiry W.S. Cancer Res. 1998; 58: 1593-1598PubMed Google Scholar). However, several lines of evidence imply that the proapoptotic activity of p53 is independent of its function as a transcription factor (20.Caelles C. Heimberg A. Karin M. Nature. 1994; 370: 220-223Crossref PubMed Scopus (835) Google Scholar, 21.Haupt Y. Rowan S. Shaulian E. Vousden K.H. Oren M. Genes Dev. 1995; 9: 2170-2183Crossref PubMed Scopus (518) Google Scholar, 22.Haupt Y. Barak Y. Oren M. EMBO J. 1996; 15: 1596-1606Crossref PubMed Scopus (206) Google Scholar). The release of cytochrome c from mitochondria is a central event in the death receptor-independent, “intrinsic,” apoptotic pathway (23.Reed J.C. Cell. 1997; 91: 559-562Abstract Full Text Full Text PDF PubMed Scopus (702) Google Scholar, 24.Green D.R. Reed J.C. Science. 1998; 281: 1309-1312Crossref PubMed Google Scholar). Cytochrome c together with ATP and Apaf-1 facilitates activation by caspase 9 of the effector caspases (25.Zou H. Henzel W.J. Liu X. Lutschg A. Wang X. Cell. 1997; 90: 405-413Abstract Full Text Full Text PDF PubMed Scopus (2746) Google Scholar, 26.Li P. Nijhawan D. Budihardjo I. Srinivasula S.M. Ahmad M. Alnemri E.S. Wang X. Cell. 1997; 91: 479-489Abstract Full Text Full Text PDF PubMed Scopus (6261) Google Scholar, 27.Saleh A. Srinivasula S.M. Acharya S. Fishel R. Alnemri E.S. J. Biol. Chem. 1999; 274: 17941-17945Abstract Full Text Full Text PDF PubMed Scopus (427) Google Scholar, 28.Hu Y. Benedict M.A. Ding L. Nunez G. EMBO J. 1999; 18: 3586-3595Crossref PubMed Scopus (410) Google Scholar), which then cleave their substrates, finally leading to the apoptotic cell death. Furthermore, cytochrome c release can also occur in death receptor-dependent, “extrinsic,” apoptotic pathways by cleavage and activation of the proapoptotic Bcl-2 family member Bid through caspase 8 (29.Luo X. Budihardjo I. Zou H. Slaughter C. Wang X. Cell. 1998; 94: 481-490Abstract Full Text Full Text PDF PubMed Scopus (3085) Google Scholar, 30.Li H. Zhou H. Xu C.-J. Yuan J. Cell. 1998; 94: 491-501Abstract Full Text Full Text PDF PubMed Scopus (3798) Google Scholar, 31.Gross A. Yin X.-M. Wang K. Wei M.C. Jockel J. Milliman C. Erdjument-Bromage H. Tempst P. Korsmeyer S.J. J. Biol. Chem. 1999; 274: 1156-1163Abstract Full Text Full Text PDF PubMed Scopus (932) Google Scholar), possibly serving as an amplification loop. Several studies were undertaken to establish the involvement of caspase activation in p53-mediated cell death (18.Müller M. Wilder S. Bannasch D. Israeli D. Lehlbach K. Li-Weber M. Friedman S.L. Galle P.R. Oren M. Krammer P.H. J. Exp. Med. 1998; 188: 2033-2045Crossref PubMed Scopus (735) Google Scholar,32.Yu Y. Little J.B. Cancer Res. 1998; 5: 4277-4281Google Scholar, 33.Ding H.-F. McGill G. Rowan S. Schmaltz C. Shimamura A. Fisher D.E. J. Biol. Chem. 1998; 273: 28378-28383Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar, 34.Fuchs E.J. McKenna K.A. Bedi A. Cancer Res. 1997; 57: 2550-2554PubMed Google Scholar, 35.Henkels K.M. Turchi J.J. Cancer Res. 1999; 59: 3077-3083PubMed Google Scholar). Recently, the requirement of Apaf-1 or caspase 9 for the p53-dependent apoptosis of oncogene-transformed murine embryonic fibroblasts has been conclusively demonstrated (36.Soengas M.S. Alarcón R.M. Yoshida H. Giaccia A.J. Hakem R. Mak T.W. Lowe S.W. Science. 1999; 284: 156-159Crossref PubMed Scopus Google Scholar). The was undertaken to the that p53 induce apoptosis by a death pathway the release of mitochondrial cytochrome in Saos-2 cells that p53 cytochrome c release to caspase activation and to the of apoptotic cell Furthermore, we demonstrate the requirement of cytosolic Bax for the cytochromec-releasing activity of in we provide a p53 and the death activation of the apoptotic machinery of The cell Saos-2 cells was from and was in and cytochrome c caspase p53 and p21/WAF1/CIP1 and Bax were from and were from and an was from caspase 9 has been J.C. H. G. D.R. 1999; 94: PubMed Google Scholar, J.M. H. Q. X. Zhou Q. D. D.R. Reed J.C. G.S. J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google Scholar). The broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD-fmk) and the caspase benzyloxycarbonyl-Asp-Glu-Val-Asp aminofluoromethylcoumarin were from adenoviral were from D. C. and I. The the p53 or the of the gene P. S. Huang D.E. R. 1994; 5: PubMed Scopus Google Scholar, Liu X. S. P. 1995; PubMed Scopus Google Scholar). The was to and of Saos-2 which was to the was for p53 gene and the empty adenoviral as before cells were in or at a of or were in at the were with the for and with growth cells were by by with growth and death was by of and propidium iodide a cycle and of was by after the cells in on for at Cytosolic extracts were as E. D.R. EMBO J. 1998; PubMed Scopus Google Scholar, E. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). In cells were by and were in a and on for cells were in a by of a type The were at for and the were at of the as well as cell extracts were by in by and at the were at were isolated from the of as E. D.R. EMBO J. 1998; PubMed Scopus Google Scholar, E. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). of the mitochondrial were with cytosolic extracts at for at for the were for the presence of cytochrome c by were in and were also by The of cytosolic or cell extracts was by the of were in for by The were to in or a by on with and the were to the at on a and after incubation with the the were was by of effector caspases was in cell extracts the caspase by means of a as J.C. H. G. D.R. 1999; 94: PubMed Google Scholar). In cleavage of was at for The activity was as the of the we p53 expression in apoptotic cell death and caspase activation in Saos-2 cells. with induced phosphatidylserine as by at by leading to at such were transduction with the of the empty an in DNA internucleosomal DNA fragmentation, was in Saos-2 cells transduced with but not in Saos-2 cells transduced with activity leading to cleavage of was in extracts from Saos-2 cells at and after transduction with demonstrated of cleavage of and cleavage of the caspase substrates and of p53 as well as induction of the p53 gene p21/WAF1/CIP1 could as as after transduction was to the apoptotic cell death after p53 expression in Saos-2 cells was on caspase The addition of the caspase inhibitor at a of almost completely cell death and DNA as induced by expression of p53 in Saos-2 cells. Several mitochondrial genes reactive oxygen species were to induced by p53 (15.Polyak K. Xia Y. Zweier J.L. Kinzler K.W. Vogelstein B. Nature. 1997; 389: 300-305Crossref PubMed Scopus (2246) Google Scholar), a of reactive oxygen species as of p53-mediated However, in Saos-2 the addition to of p53-induced cell death at of or induced cell death in Saos-2 cells not p53 activates caspases by the release of cytochrome c from the mitochondrial intermembrane the P. Nijhawan D. Budihardjo I. Srinivasula S.M. Ahmad M. Alnemri E.S. Wang X. Cell. 1997; 91: 479-489Abstract Full Text Full Text PDF PubMed Scopus (6261) Google Scholar, H. Y. Liu X. Wang X. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar), of Saos-2 cells was at transduction with or with Cytochrome the cytosolic of Saos-2 cells could as as after transduction with this with a of the from cytochrome c such could after transduction of Saos-2 cells with of mitochondrial release were after adenoviral expression of p53 in the p53null cell not The proapoptotic Bcl-2 family member which mitochondrial cytochrome c release J.M. Q. L. D. Reed J.C. S. A. 1998; PubMed Scopus Google Scholar, E. N.J. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar), is to by p53 in cell lines (13.Miyashita T. Reed J.C. Cell. 1995; 80: 293-299Abstract Full Text PDF PubMed Scopus (305) Google Scholar). In an of Bax expression was in Saos-2 cells p53 but Bax were after the of cytochrome of death receptors such as CD95/Fas/APO-1 or tumor factor also can in cytochrome c release activation of caspase by cleavage and activation of Bid can then mitochondria and induce the release of cytochrome c (29.Luo X. Budihardjo I. Zou H. Slaughter C. Wang X. Cell. 1998; 94: 481-490Abstract Full Text Full Text PDF PubMed Scopus (3085) Google Scholar, 30.Li H. Zhou H. Xu C.-J. Yuan J. Cell. 1998; 94: 491-501Abstract Full Text Full Text PDF PubMed Scopus (3798) Google Scholar, 31.Gross A. Yin X.-M. Wang K. Wei M.C. Jockel J. Milliman C. Erdjument-Bromage H. Tempst P. Korsmeyer S.J. J. Biol. Chem. 1999; 274: 1156-1163Abstract Full Text Full Text PDF PubMed Scopus (932) Google Scholar). However, Bid cleavage in death apoptosis as induced by has been shown to occur of mitochondrial cytochrome c release and was prevented by the caspase inhibitor X.-M. M. J. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). the p53-mediated cytochrome c release in was on the caspase 8 cleavage of we the caspase inhibitor which at a of is effector caspases such as caspases and and caspases such as caspases and in vitro M. B. R. J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google the addition of directly after transduction with did not prevent mitochondrial cytochrome c release caspase activity is required for Bid cleavage and activation the death 8 this a for this pathway in p53-induced cytochrome from mitochondria in Saos-2 cells. the mechanism of p53-induced cytochrome c cytosolic extracts from Saos-2 cells transduced with or with the empty were and with isolated murine extracts from cells p53 contained a cytochrome c-releasing activity in vitro, which was not by addition of also the requirement of caspase activity for the in vitro release by When p53 was immunodepleted from the cytosolic the cytochrome c-releasing activity was still This a of p53 on mitochondria in in vitro p53 has been to the proapoptotic Bcl-2 family member Bax in cell types (13.Miyashita T. Reed J.C. Cell. 1995; 80: 293-299Abstract Full Text PDF PubMed Scopus (305) Google Scholar), which was shown to induce cytochrome c release to isolated mitochondria (36.Soengas M.S. Alarcón R.M. Yoshida H. Giaccia A.J. Hakem R. Mak T.W. Lowe S.W. Science. 1999; 284: 156-159Crossref PubMed Scopus Google Scholar, E. N.J. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar), the of Bax in this in vitro of p53-mediated cytochrome c release was of but not of p53 or of the the cytochrome c-releasing activity from the of p53 cells. Thus, the cytochrome c-releasing activity of p53 was on the presence of Bax in the are pathways a death to the apoptotic The pathway of death receptors such as CD95/Fas/APO-1 or by of their which leads to of the caspase 8 and and to its S. Cell. 1997; 88: Full Text Full Text PDF PubMed Scopus Google Scholar). caspase 8 can directly cleave and the effector caspases M. K. A. J. C. Zhang M. R. M. Krammer P.H. Cell. 1996; 817-827Abstract Full Text Full Text PDF PubMed Scopus Google Scholar, D. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar), or can cleave Bid to induce the release of mitochondrial which also leads to activation of effector caspases with Apaf-1 and caspase 9 in the presence of ATP (29.Luo X. Budihardjo I. Zou H. Slaughter C. Wang X. Cell. 1998; 94: 481-490Abstract Full Text Full Text PDF PubMed Scopus (3085) Google Scholar, 30.Li H. Zhou H. Xu C.-J. Yuan J. Cell. 1998; 94: 491-501Abstract Full Text Full Text PDF PubMed Scopus (3798) Google Scholar, 31.Gross A. Yin X.-M. Wang K. Wei M.C. Jockel J. Milliman C. Erdjument-Bromage H. Tempst P. Korsmeyer S.J. J. Biol. Chem. 1999; 274: 1156-1163Abstract Full Text Full Text PDF PubMed Scopus (932) Google Scholar). This activation of the mitochondrial pathway in cells with of death receptors or caspase 8 and act as an amplification E. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). is evidence for a of p53 in of expression of death receptors in several cell types (16.Owen-Schaub L.B. Zhang W. Cusack J.C. Angelo L.S. Santee S.M. Fujiwara T. Roth J.A. Deisseroth A.B. Zhang W.W. Kruzel E. et al.Mol. Cell. Biol. 1995; 15: 3032-3040Crossref PubMed Scopus (690) Google Scholar, 17.Bennett M. MacDonald K. Chan S.-W. Luzio J.P. Simari R. Weissberg P. Science. 1998; 282: 290-293Crossref PubMed Scopus (654) Google Scholar, 18.Müller M. Wilder S. Bannasch D. Israeli D. Lehlbach K. Li-Weber M. Friedman S.L. Galle P.R. Oren M. Krammer P.H. J. Exp. Med. 1998; 188: 2033-2045Crossref PubMed Scopus (735) Google Scholar, 19.Sheikh M.S. Burns T.F. Huang Y. Wu G.S. Amundson S. Brooks K.S. Fornace Jr., A.J. El-Deiry W.S. Cancer Res. 1998; 58: 1593-1598PubMed Google Scholar). In contrast, the death receptor-independent, apoptotic pathway is directly by a death leading to the release of cytochrome c from the mitochondrial intermembrane the which in the presence of facilitates and activation of Apaf-1 and caspase leading to activation of caspase and effector caspases D.R. Reed J.C. Science. 1998; 281: 1309-1312Crossref PubMed Google Scholar). The release of cytochrome c is by the and of the Bcl-2 family (23.Reed J.C. Cell. 1997; 91: 559-562Abstract Full Text Full Text PDF PubMed Scopus (702) Google Scholar, J.M. Q. L. D. Reed J.C. S. A. 1998; PubMed Scopus Google Scholar, E. N.J. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar, R.M. E. D.R. Science. 1997; PubMed Scopus Google Scholar, A.J. H. A. B.S. S.W. M. EMBO J. 1999; 18: PubMed Scopus Google Scholar, S. A. A. R. S. S. K. B. J. Biol. 1999; PubMed Scopus Google Scholar). of such as anticancer and growth factor were shown to apoptotic cell death independent of death thus directly this apoptotic pathway E.J. McKenna K.A. Bedi A. Cancer Res. 1997; 57: 2550-2554PubMed Google X.-M. M. J. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar, C.M. G.S. 1997; 90: PubMed Google Scholar, S. E. M. K. 1999; PubMed Google Scholar, M.C. A. 1999; PubMed Scopus Google Scholar). Furthermore, in Apaf-1 or caspase which in the pathway act of mitochondrial leading to embryonic and their cells are to death induction of apoptosis by and a variety of anticancer drugs F. G. Roth K.A. P. Cell. 1998; 94: Full Text Full Text PDF PubMed Scopus Google Scholar, H. Yoshida R. A.J. Hakem A. Hakem R. J.M. Mak T.W. Cell. 1998; 94: Full Text Full Text PDF PubMed Scopus Google Scholar, R. Hakem A. G.S. M. M.S. A. J.L. D. W. J. Yoshida R. Lowe S.W. Mak T.W. Cell. 1998; 94: Full Text Full Text PDF PubMed Scopus Google Scholar). the mitochondrial and the in the pathway are well the of the of mitochondria in this pathway is of studies a central of the p53 tumor suppressor gene in the of a death to the apoptotic pathway (11.Lowe S.W. Ruley H.E. Jacks T. Housman D.E. Cell. 1993; 74: 957-967Abstract Full Text PDF PubMed Scopus (2963) Google Scholar, 12.Lowe S.W. Schmitt E.M. Smith S.W. Osborne B.A. Jacks T. Nature. 1993; 362: 847-849Crossref PubMed Scopus (2767) Google Scholar, K. Xia Y. Zweier J.L. Kinzler K.W. Vogelstein B. Nature. 1997; 389: 300-305Crossref PubMed Scopus (2246) Google Scholar, Knudson C.M. Korsmeyer S.J. Lowe S.W. S. A. 1997; 94: PubMed Scopus Google Scholar). Recently, et M.S. Alarcón R.M. Yoshida H. Giaccia A.J. Hakem R. Mak T.W. Lowe S.W. Science. 1999; 284: 156-159Crossref PubMed Scopus Google Scholar), murine embryonic evidence that apoptotic cell death as induced by oncogenic p53 as well as Apaf-1 and caspase 9 (36.Soengas M.S. Alarcón R.M. Yoshida H. Giaccia A.J. Hakem R. Mak T.W. Lowe S.W. Science. 1999; 284: 156-159Crossref PubMed Scopus Google Scholar). Thus, p53 to a to the apoptotic machinery of However, the p53 activation and the apoptotic machinery still to that p53 able to effector caspases by the release of mitochondrial cytochrome c the this we the cell Saos-2 on its p53null and its ability to cell death p53 expression. This to p53 activation lead to mitochondrial cytochrome c release. could been to of such as anticancer drugs or however, several p53-dependent and pathways in cell which could with of the In addition to their p53 Saos-2 cells also a which for the of a cell cycle in the expression of p53 not Thus, that the apoptosis of Saos-2 as induced by p53 in from the of by p53 in a p53null we could induce apoptotic cell death in Saos-2 which was prevented by caspase for the evidence for the release of mitochondrial cytochrome c to the activation of caspases by receptors such as CD95/Fas/APO-1 or tumor factor by caspase 8 cleavage of can also induce mitochondrial cytochrome c release (29.Luo X. Budihardjo I. Zou H. Slaughter C. Wang X. Cell. 1998; 94: 481-490Abstract Full Text Full Text PDF PubMed Scopus (3085) Google Scholar, 30.Li H. Zhou H. Xu C.-J. Yuan J. Cell. 1998; 94: 491-501Abstract Full Text Full Text PDF PubMed Scopus (3798) Google Scholar, 31.Gross A. Yin X.-M. Wang K. Wei M.C. Jockel J. Milliman C. Erdjument-Bromage H. Tempst P. Korsmeyer S.J. J. Biol. Chem. 1999; 274: 1156-1163Abstract Full Text Full Text PDF PubMed Scopus (932) Google Scholar). However, in the release of cytochrome c as induced by p53 in in vitro was on caspase thus the involvement of a death and activation of caspase 8 and which can in response to p53-dependent apoptotic occur of caspase activation the cytochrome 9 pathway X.-M. M. J. D.R. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar, E.A. R.M. Wang Reed J.C. Alnemri E.S. D.R. S.J. J. Biol. 1999; Scopus Google Scholar). evidence was for a of p53 on isolated mitochondria in vitro, by we could demonstrate the requirement of cytosolic Bax for the cytochromec-releasing activity of on and the of (36.Soengas M.S. Alarcón R.M. Yoshida H. Giaccia A.J. Hakem R. Mak T.W. Lowe S.W. Science. 1999; 284: 156-159Crossref PubMed Scopus Google Scholar), we the for the induction of apoptosis by p53 the release of mitochondrial cytochrome c by a pathway cytosolic Cytosolic cytochrome the activation of caspase and effector caspases by caspase 9 with the Apaf-1 in the presence of p53 cytochrome c release by cytosolic Bax which was in cell lines (13.Miyashita T. Reed J.C. Cell. 1995; 80: 293-299Abstract Full Text PDF PubMed Scopus (305) Google Scholar), or p53 leads to and mitochondrial of Bax by a pathway Bcl-2 family S. A. A. R. S. S. K. B. J. Biol. 1999; PubMed Scopus Google Scholar, G.J. L. J. C. J.A. J. Biol. 1999; PubMed Scopus Google Scholar) or B. B. and of the of for their and D. C. and I. are for their and for adenoviral
Schüler et al. (Wed,) studied this question.
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