WO1998002579A9 - Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere - Google Patents

Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere

Info

Publication number
WO1998002579A9
WO1998002579A9 PCT/US1997/012090 US9712090W WO9802579A9 WO 1998002579 A9 WO1998002579 A9 WO 1998002579A9 US 9712090 W US9712090 W US 9712090W WO 9802579 A9 WO9802579 A9 WO 9802579A9
Authority
WO
WIPO (PCT)
Prior art keywords
apoptosis
cytochrome
cells
composition
cpp32
Prior art date
Application number
PCT/US1997/012090
Other languages
English (en)
Other versions
WO1998002579A1 (fr
Filing date
Publication date
Application filed filed Critical
Priority to EP97933393A priority Critical patent/EP0918882A1/fr
Priority to JP50617298A priority patent/JP2001526525A/ja
Priority to AU36587/97A priority patent/AU727222B2/en
Publication of WO1998002579A1 publication Critical patent/WO1998002579A1/fr
Publication of WO1998002579A9 publication Critical patent/WO1998002579A9/fr

Links

Definitions

  • the field of this invention is the area of apoptosis (programmed cell death) and methods for the study of the regulation thereof.
  • the present invention provides an in vitro system for the analysis of apoptosis and specific regulators of the apoptotic pathway.
  • Apoptosis is a distinct form of cell death controlled by an internally encoded suicide program [reviewed by friendshipr, H. (1995) Science 267, 1445-1449; White, E. (1996) Gene & Dev. 10, 1-15].
  • Morphologic changes associated with apoptosis include condensation of nucleoplasm and cytoplasm, blebbing of cytoplasmic membranes, and fragmentation of the cell into apoptotic bodies that are rapidly phagocytosed by neighboring cells [Kerr, J. (1971) J. Pathol. 105, 13-20; Wyllie et al. (1980) Int. Rev. Cytol. 68, 251-305] .
  • Biochemical markers of apoptosis include DNA fragmentation into nucleosomal fragments [Wyllie, A. (1980) Nature 284, 555-556], activation of the interleukin lb converting enzyme (ICE)-family of proteases [Schlegel et al. , 1996; Duan et al. (1996) J. Biol. Chem. 271 , 1621-1625; Wang et al. (1996) EMBO J. 15, 1012-1020], and cleavage of substrates of the ICE-family of proteases, including poly(ADP-ribose) polymerase (PARP) [Tewari et al. (1995) Cell 81, 801-809; Nicholson et al.
  • PARP poly(ADP-ribose) polymerase
  • the cell suicide program is illustrated by genetic studies in the nematode Caenorhabditis elegans [Hengartner and Horvitz (1994) Philos. Trans. R. Soc. London Ser. B 345, 243-246].
  • Two genes involved in the control of programmed cell death in C. elegans have been well characterized.
  • One gene (ced-9) encodes a protein that prevents cells from undergoing apoptosis [Hengartner et al. (1992) Nature 356, 494-499]
  • the ced-3 gene encodes a protease required for initiation of apoptosis [Yuan and Horvitz (1990) Dev. Biol. 138, 33-41].
  • the bcl-2 family of genes are mammalian counterparts of ced-9 [Hengartner and Horvitz (1994) Cell 76, 665-676]. Over-expression of bcl-2 coding sequences prevents mammalian cells from undergoing apoptosis in response to a variety of stimuli [reviewed by Reed, J. C. (1994) J. Cell Biol. 124, 1-6].
  • the BCL-2 protein is located primarily on the outer membranes of mitochondria [Monaghan et al. (1992) . Hist. Cytochem. 40, 1819-1825; Krajewski et al. (1993) Cancer Res. 53, 4701-4714; de Jong et al. (1994) Cancer Res. 54, 256-260].
  • BCL-2 The presence of BCL-2 on the mitochondria surface is correlated with a block in the release of cytochrome c in response to triggers of apoptosis in cells which do not express the BCL-2 protein on the mitochondrial surface [Yang et al. (1997) Science 275, 1129-1132].
  • the Bcl-2 protein inhibits apoptosis by preventing release of holocytochrome c from the mitochondrial membrane and also prevents depolarization of the mitochondrial membrane.
  • the CED-3 protein is a cysteine protease related to the ICE-family of proteases in mammalian cells [Yuan et al. (1993) Cell 75, 641-652].
  • the closest mammalian homolog of CED-3 is CPP32 [Fernandes-
  • CPP32 which is also called caspase-3, is closely related to CED-3 in terms of amino acid sequence identity and substrate specificity [Xue and Horvitz (1995) Nature 377, 248-251]. Like CED-3 in C.
  • CPP32 normally exists in the cytosolic fraction as an inactive precursor; that precursor is activated proteolytically in cells undergoing apoptosis [Schlegel et al. (1996) /. Biol. Chem. 271, 1841-1844, 1996; Wang et al. (1996) supra]. Further evidence for the requirement for active CPP32 in apoptosis is that a tetrapeptide aldehyde inhibitor that specifically inhibits CPP32 activity blocks the ability of cytosol from apoptotic cells to induce apoptosis-like changes in normal nuclei in vitro. [Nicholson et al. (1995) supra].
  • CPP32 Triggering of apoptosis by activated CPP32 is part of the highly regulated mechanism for initiation of apoptosis; careful regulation of this pathway is necessary to prevent unwanted cell death.
  • CPP32 is activated by multiple proteolytic cleavages of its 32 kDa precursor form, generating the 17/11 kDa or 20/11 kDa active form [Nicholson et al. (1995) supra; Wang et al. (1995) supra].
  • CPP32 is activated by cleavage at aspartic acid residues, a hallmark of ICE-like proteases [Thornberry et al.
  • the present invention provides an in vitro system and methods for the analysis of the regulation of apoptosis and for the identification of activators and inhibitors of the apoptotic pathway; the present system is improved over prior art systems for the study of apoptosis in that the prior art systems depended on cell free extracts prepared from organisms in which the apoptosis pathway had already been induced.
  • the present system and methods permit freedom from the potential interference of apoptosis-inducing factors or other conditions on which prior art systems have relied.
  • the present invention provides an in vitro system for analysis of apoptosis and its regulation, where the test system includes a 100,000 x g supernatant of HeLa cells from suspension culture (S-100).
  • the HeLa S-100 to which challenge compounds are added, is assayed for CPP32 proteolytic activity using radiolabeled poly(adenosine diphosphate-ribose polymerase (PARP) and radiolabeled sterol regulatory binding protein 2 (SREBP-2) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography.
  • PARP radiolabeled poly(adenosine diphosphate-ribose polymerase
  • SREBP-2 radiolabeled sterol regulatory binding protein 2
  • SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis
  • the radiolabeled PARP and SREBP-2 can be prepared by in vitro translation in the presence of 35 S-methionine as described in Example 3 herein.
  • the HeLa S-100 to which challenge compounds are added, is assayed for DNA fragmentation activity, by incubating the treated S-100 with hamster liver cell nuclei and then extracting the genomic DNA and analyzing by agarose gel electrophoresis.
  • the specific proteolytic activity is accelerated by the addition of dATP or dADP (at a concentration from about 0.1 to about 2 mM, preferably about 1 mM. DNA fragmenting activity is similarly dependent on the presence of dATP. It has been demonstrated that cytochrome c is required in the cell-free extract for the dATP-dependent activation of the apoptotic pathway, especially for the activation of the apoptosis marker protease.
  • the present invention provides a cell-free system which duplicates the features of the apoptotic program, including the activation of CPP32 and DNA fragmentation. Apoptosis in this system is initiated by the presence of soluble cytochrome c and dATP at sufficient concentrations. This system allows the fractionation and purification of the biochemical components that trigger the activation of the apoptotic proteases and DNA fragmentation.
  • the present invention further provides a method for identifying antagonists of dATP in the cytosol of adenosine deaminase-deficient cells, such as T cells from persons with severe combined immunodeficiency.
  • dATP levels in adenosine deaminase-deficient cells are elevated in comparison to those of normal cells, and without wishing to be bound by any particularly, this is believed to contribute to the symptoms of the deficiency .
  • the present invention also provides methods for identification of compounds which trigger apoptosis even where the bcl-2 oncogene protein is present.
  • the bcl-2 oncogene is associated with resistance to chemotherapy in human cancer, and compounds which cause CPP32 protease and DNA fragmentation nuclease- activation in bcl-2 oncogene extracts can be identified in the cell free assays of the present invention where the S-100 extract is prepared from BCL-2 expressing cells.
  • the present invention allows the identification of compounds which effectively increase the apoptotic response to dATP and/or cytochrome c, including those which increase dATP levels in treated cells and those which promote release of cytochrome c from mitochondrial membranes.
  • Such compounds can be used to increase the effectiveness of chemotherapeutic agents which act by inducing apoptosis.
  • Figures 1A-1D illustrate dATP-dependent activation of CPP32 and DNA fragmentation in vitro.
  • Aliquots (10 ⁇ l) of HeLa cell S-100 (50 ⁇ g) were incubated alone (lane 1), in the presence of 1 mM ATP (lane 2), or in the presence of 1 mM dATP (lane 3) at 30°C for 1 hr in a final volume of 20 ⁇ l of buffer A.
  • Fig. 1A samples were subjected to SDS-PAGE and transferred to a nitrocellulose filter, probed with a monoclonal anti-CPP32 antibody, and the antigen/antibody complex was visualized by the ECL method.
  • the filter was exposed to Kodak X-OMAT AR X-ray film for 1 min.
  • Fig. IB an aliquot of 10 ⁇ l of in vitro translated, 35 S-labeled PARP was added to each reaction. After 5 min, the samples were subjected to SDS-PAGE and transferred to a nitrocellulose filter. The filter was exposed to film for 2 hr at room temperature.
  • Fig. IC a 5 ⁇ l aliquot of in vitro translated, 35 S-labeled SREBP-2 was added to each reaction. After incubation at 30°C for 30 min, the samples were subjected to SDS-PAGE, the gel was dried and exposed to film for 2 hr at room temperature.
  • Fig. IB an aliquot of 10 ⁇ l of in vitro translated, 35 S-labeled PARP was added to each reaction. After 5 min, the samples were subjected to SDS-PAGE and transferred to a nitrocellulose filter. The filter was exposed to film for 2 hr at room temperature.
  • Fig. IC a 5 ⁇ l aliquot of in vitro translated,
  • 2A shows the results of incubating a 10 ⁇ l aliquot of HeLa S-100 (50 ⁇ g) was incubated with a 3 ⁇ l aliquot of in vitro translated, 35 S-labeled CPP32 at 30°C for 1 hr in a final volume of 20 ⁇ l in the presence of 1 mM indicated nucleotide.
  • the samples were subjected to SDS-PAGE and transferred to a nitrocellulose filter. The filter was exposed to film for 16 hours at room temperature.
  • FIG. 4 shows the results of Mono S column purification of Apaf-2.
  • the Apaf-2 activity that bound to the phosphocellulose column was purified through the Mono S column as described in Example 7.
  • Fig. 4 A shows the results of incubation of 1 ⁇ l aliquots of Mono S column fractions with aliquots of 10 ⁇ l phosphocellulose flow through fraction and 3 ⁇ l of in vitro translated, 35 S-labeled CPP32 at 30°C for 1 hr in the presence of 1 mM dATP in a final volume of 20 ⁇ l of buffer A. Samples were subjected to SDS-PAGE, transferred to a nitrocellulose filter, and the filter was exposed to film for 16 hours at room temperature.
  • Fig. 4B aliquots (30 ⁇ l) of the Mono-S fractions were subjected to 15% SDS-PAGE and the proteins were visualized by silver staining.
  • Figure 5 provides the absorption spectrum of Apaf-2.
  • An aliquot of 1 ml of Apaf-2 purified through the Mono S column was subjected to abso ⁇ tion spectrum scanning using a CARY 219 spectrophotometer. Abso ⁇ tion spectrum was recorded between 330 nm and 600 nm at a scanning speed of 1 nm/sec.
  • Figure 6 demonstrates that cytochrome c proteins from bovine heart and rat liver have Apaf-2 activity.
  • Figures 7A-7D demonstrate immunodepletion of cytochrome c from HeLa S-100 and reconstitution of dATP-dependent activation of CPP32, DNA fragmentation and nuclear mo ⁇ hological change using purified cytochrome c. Cytochrome c present in the HeLa cell S-100 was immunodepleted as described in the Example
  • Fig. 7A 10 ⁇ l aliquots of HeLa S-100 (50 ⁇ g) (lanes 1 and 2), or 10 ⁇ l aliquots of HeLa S-100 immunodepleted of cytochrome c (lanes 3 and 4), or 10 ⁇ l of HeLa S-100 immunodepleted of cytochrome c supplemented with 0.2 ⁇ g Apaf-2 purified through the Mono S column (H) (lanes 5 and 6), bovine heart cytochrome c (B) (lanes 7 and 8), or rat liver cytochrome c (R) (lanes 9 and 10), were incubated with aliquots of 3 ⁇ l in vitro translated, 35 S-labeled CPP32 in the absence (lanes 1, 3, 5, 7, 9) or presence (lanes 2, 4, 6, 8,
  • DNA fragmentation assays were carried out as in Panel C using HeLa S-100 immunodepleted of cytochrome c alone (a,b) or supplemented with Apaf-2 purified through Mono S column step (c,d) in the absence (a,c) or presence of 1 mM dATP (b,d).
  • FIG. 8 illustrates dATP and cytochrome c-dependent activation of CPP32 in S-100 cytosol preparations (immunodepleted of cytochrome c) from human embryonic kidney 293 cells and human monoblastic U937 cells.
  • CPP32 activation reactions were carried out as described in Figure 7 except 25 ⁇ g of S-100 was used in each reaction. 1 mM of dATP was present in lanes 2, 4, 6, 8, 10, and 12. Lanes 1 and 2, S-100 fraction from 293 cells; Lanes 3-4, S-100 fraction from 293 cells immunodepleted of cytochrome c; lanes 5 and
  • Hela cells were set up at 5 x 10 s cells per 100 mm dish in medium A as described hereinbelow.
  • cells were harvested, collected by centrifugation (1000 g, 10 min, 4°C).
  • the cell pellet was suspended in 5 volumes of ice-cold buffer A containing 250 mM sucrose.
  • the cells were disrupted by douncing 3 times in a 5 ml Wheaton douncer with a pestle polished with sand paper.
  • the supernatants were further centrifuged at 10 5 x g for 30 min in a table top ultracentrifuge (Beckman Instruments, Fullerton, CA).
  • S-cytosol The resulting supernatants were designated as S-cytosol.
  • Figures 10A-10B shows increased release of cytochrome c to the cytosol upon apoptotic stimulation.
  • HeLa cells were treated as described in Figure 9.
  • staurosporine at a final concentration of 1 ⁇ M was added to the medium as indicated.
  • S-cytosols were prepared as described in Figure 9.
  • Fig. 10A a 50 ⁇ g aliquot of HeLa cell S-100 as in Figures 1-7
  • lane 1 S-cytosol from HeLa cells
  • lane 2 S-cytosol from HeLa cells treated with staurosporine for 6 hr.
  • lane 4 aliquot of 0.2 ⁇ g of Apaf-2 purified through Mono S column step. Proteins were separated using 15 % SDS-PAGE, transferred to a nitrocellulose filter, and probed with a monoclonal anti-cytochrome c antibody and the antigen/antibody complex was visualized by the ECL method as described herein. Kodak X-OMAT AR X-ray film was exposed for 15 seconds. The arrow denotes the position of cytochrome c; X denotes protein bands cross-reacting with this antibody.
  • Fig 10B aliquots containing 4.5 ⁇ g of S-cytosol from HeLa cells (-staurosporine) or HeLa cells treated with 1 ⁇ M staurosporine for 6 hr (+ staurosporine) were incubated with 10 ⁇ l aliquots of in vitro translated, 35 S-labeled PARP for 30 min at 30° C in a volume of 20 ⁇ l of buffer A.
  • Samples were then subjected to 12% SDS-PAGE, transferred to a nitrocellulose filter, and film was exposed for 4 hr at room temperature.
  • Apoptosis, or cell death, is a natural phenomenon. Modulation of normal apoptosis or activation of the apoptotic pathway in cells in which apoptosis is inhibited due to the expression of oncogenes, for example, can lead to longer and enhanced life and/or improved medical treatment methods, for example, in cancer patients.
  • the present invention provides a method for the identification of inducers and/or inhibitors of apoptosis in a cell-free system comprising 100,000 x g supernatant of cell cytosol (S-100) prepared from actively growing cells and containing the inactive CPP32 and nuclease precursors.
  • S-100 cell cytosol
  • the S-100 is prepared from mammalian cells, for example, HeLa cells.
  • Activation of the apoptosis marker protease CPP32 and the marker nuclease are triggered in this system in the presence of dATP and soluble cytochrome c in a 100,000 x g cytosol supernatant.
  • Modification of the assay preparation conditions allows the identification of compounds, proteins or compositions which can substitute either for the dATP or the soluble cytochrome c or for both.
  • Initiation of the apoptotic pathway is detected by the proteolytic cleavage of SREBPs or PARP by the CPP32 protease which is activated at an early step of the apoptotic pathway.
  • Triggering of the apoptotic pathway can also be detected via the activation of the nuclease.
  • Active CPP32 protease and active apoptotic DNA fragmentation nuclease are marker enzymes of the apoptotic pathway.
  • soluble cytochrome c and dATP trigger activation of the marker enzymes for apoptosis. It is understood that analogs of dATP and dADP function in triggering the apoptotic activation as well.
  • Compounds or proteins which inhibit the initiation of the apoptotic pathway are detected by their prevention of the activation of the CPP32 protease or the marker nuclease in the presence of cytochrome c and dATP, conditions which normally activate the pathway.
  • Compounds or proteins which counteract the apoptosis-inhibiting activity of the bcl-2 gene product (or of other oncogene products) can be identified by their ability to allow the activation of the marker enzymes of the apoptotic pathway even in the presence of dATP and cytochrome c in S-100 extracts of cells expressing bcl- 2 or similar oncogenes.
  • compositions identified in the present assay system can be then used to increase the activity of chemotherapeutic agents used in the treatment of cancers and other hype ⁇ lastic disorders, especially in cells expressing oncogenic bcl-2 or other oncogenes which decrease apoptosis.
  • Activation of CPP32 and DNA fragmentation are two well characterized biochemical markers of apoptosis and its initiation.
  • S-100 cytosolic supernatant
  • the activation of CPP32 is the result of cleavage of its 32 kDa precursor into the 20 kDa NH 2 -terminal fragment and 11 kDa COOH- terminal fragment [Nicholson et al. (1995) supra], thus the activation of CPP32 in the HeLa cell S-100 was monitored by Western blot analysis using a monoclonal antibody against the 20 kDa fragment of CPP32 ( Figure 1A).
  • the enzymatic activity of CPP32 was assayed by measuring the cleavage of two 35 S-labeled substrates, PARP ( Figure IB) and SREBP-2 ( Figure IC). DNA fragmentation was assayed by incubating the HeLa cell S-100 with nuclei isolated from hamster liver followed by genomic DNA extraction and analysis by agarose gel electrophoresis. We found that deoxyadenosine-5-triphos ⁇ hate (dATP) markedly accelerated the activation of CPP32 in the HeLa cell S-100. As shown in Figs.
  • dATP deoxyadenosine-5-triphos ⁇ hate
  • HeLa cell S-100 extract in the presence of dATP induced DNA fragmentation when incubated with hamster liver nuclei (Fig. ID, lane 3). Such fragmentation did not occur with HeLa S-100 in the presence or absence of ATP, confirming the requirement for dATP ( Figure ID, lanes 1 and 2).
  • Apaf-1 The factor(s) that flow through the phosphocellulose column are designated apoptotic protease activating factor- 1 (Apaf-1) and the factor that bound to the column is designated apoptotic protease activating factor-2 (Apaf-2). It is understood that "Apaf-1 " may represent more than one protein or it may represent a combination of protein(s) and other factors.
  • Apaf-2 activity was assayed by recombining with Apaf-1 after purification by the following steps.
  • the Apaf-2 fraction was subjected to 50% ammonium sulfate precipitation. All of the activity remained in the supernatant while most of the protein precipitated (Table I).
  • the supernatant was loaded onto a phenyl- sepharose (hydrophobic interaction) column and the activity was eluted with 1 M ammonium sulfate.
  • the eluate was passed through a gel filtration column; active fractions were subjected to sequential Mono Q (anion exchange) and Mono S (cation exchange) chromatography.
  • the Apaf-2 activity flowed through the Mono Q column, and the flow through was directly loaded onto the Mono S column.
  • Bound Apaf-2 activity was then eluted with a 100-300 mM NaCl linear salt gradient.
  • the fractions from the Mono S column were collected and assayed.
  • the Apaf-2 activity eluted from the Mono S column at approximately 120 mM NaCl (fractions 2-4).
  • the active fractions were analyzed by SDS-PAGE (Fig. 4B).
  • a protein of apparent molecular mass of 15 kDa was co-eluted with the activity. No other proteins were detected by silver staining in the active Apaf-2 fractions.
  • Table I summarizes the results of a complete purification of Apaf-2 starting with the S-100 fraction from 20-liters of HeLa cells (348.5 mg protein).
  • the Apaf-2 protein was purified more than 2000-fold with an overall recovery of 152% activity. The > 100% recovery indicates the elimination of inhibitory activities during the purification.
  • Purified Apaf-2 had a noticeable pink color, and it showed absorbance peaks at 415, 520 and 549 nm, a spectrum shared by reduced cytochrome c [Margoliash and Walasek (1967) Meth. Enzymol. X, 339-348] .
  • Identity of Apaf-2 with cytochrome c was confirmed by comparison of amino acid sequences generated from tryptic peptides isolated from the 15 kDa Apaf-2 with known cytochrome c amino acid sequence information. All those sequences show 100% identity with portions of the reported sequence of human cytochrome c (Table II).
  • cytochrome c has Apaf-2 activity
  • purified bovine heart and rat liver cytochrome c were tested for Apaf-2 activity.
  • cytochrome c from both sources initiated dATP-dependent activation of CPP32 as efficiently as Apaf-2 (lanes 3-6).
  • cytosols were prepared from human embryonic kidney 293 cells and human monoblastic leukemia U937 cells. As shown in Figure 8, S-100 fractions from both cell types contained a dATP-dependent CPP32 activating activity (Lanes 1, 2 and 7, 8). Immunodepletion of cytochrome c from these cytosols resulted in the loss of CPP32 activating activity (lanes 3, 4 and 9, 10) and addition of purified cytochrome c restored the activity (lane 5, 6 and 11 , 12). Human cytochrome c is encoded by a single copy nuclear gene [Evans and Sca ⁇ ulla (1988) Proc. Natl.
  • cytochrome c is translated on cytoplasmic ribosomes as apocytochrome c.
  • the heme group of cytochrome c is attached to apocytochrome c upon its translocation into mitochondria; holocytochrome c is a soluble protein located in the intermembrane space of mitochondria [Gonzales and Neupert (1990) J. Bioenergetics & Biomembranes 22, 753-768].
  • the presence of cytochrome c in the cytosolic fraction can therefore be the result of ruptured outer mitochondrial membrane by hypotonic shock during its preparation.
  • cytosol from HeLa cells was prepared in the presence of 250 mM sucrose to protect mitochondrial integrity. The cells were broken gently by douncing in a sand paper polished piston [Hayakawa et al. (1993) Mol. Cell. Biochem. 119, 95-103]. Cytosol prepared this way (designated S-cytosol) contained little cytochrome c as compared to the cytosol used in the previous experiments ( Figure 10A, lanes 1 and 2). As shown in Figure 9, S-cytosol was incapable of initiating the dATP-dependent activation of CPP32 (lanes 1 and 2) unless purified cytochrome c was added (lanes 3 and 4).
  • cytochrome c The requirement for cytochrome c in the apoptotic program in vitro indicates there is increased release of cytochrome c to the cytosol in cells undergoing apoptosis.
  • HeLa cells were treated with staurosporine.
  • Staurosporine is a broad-spectrum inhibitor of protein kinases, and it has been found to be a potent apoptosis inducer in a variety of cell types [Rueggs and Burgess (1989) Trends Pharmacol. Sci. 10, 218-220; Jacobson et al. (1993) Nature 361, 365-36; Wang et al. (1996) supra].
  • Cytosol was prepared from staurosporine-treated cells using sucrose containing buffer, and the cells were dounced by the sand paper polished piston.
  • staurosporine treatment of HeLa cells resulted in activation of the endogenous CPP32 as detected by the cleavage of PARP.
  • S-cytosol from staurosporine-treated HeLa cells contained markedly elevated cytochrome c as compared to that from non-treated cells ( Figure 10A, lanes 2 and 3). The same phenomenon was also observed in human monoblastic U937 cells. Arabinosylcytosine, etoposide and mitoxantrone HCl also act to initiate apoptosis.
  • the present invention provides an in vitro system that faithfully duplicates the two best characterized biochemical markers of apoptosis, i.e. DNA fragmentation into nucleosomal fragments and the activation of the
  • ICE-related apoptotic protease CPP32 This in vitro system allowed us to fractionate and begin to isolate the required components.
  • One required protein factor was purified to homogeneity and identified as the human cytochrome c.
  • the present dATP- and cytochrome c-dependent in vitro apoptosis system represents a general apoptotic program. Identical results were obtained from cytosols of HeLa cells, human embryonic kidney 293 cells, and human monoblastic U937 cells.
  • dADP can substitute for dATP.
  • dADP also accumulates, although to a lesser extent than dATP [Goday et al. (1985) supra].
  • cytochrome c The fractionation of the factors necessary for dATP-dependent activation of CPP32 resulted in the identification of soluble cytochrome c'as one of the necessary components for apoptosis in vitro. It is unlikely that cytochrome c mimics the function of another protein, because cytochrome c is the only protein with Apaf-2 activity purified from the S-100 fraction. The requirement for cytochrome c was confirmed by the depletion and reconstitution experiments.
  • Cytochrome c is an essential component of the mitochondrial respiratory chain. It is a soluble protein which is localized in the intermembrane space and is loosely attached to the surface of the inner mitochondrial membrane [Gonzales and Neupert (1990) supra]. Cytochrome c is translated by cytoplasmic ribosomes and follows a unique pathway into mitochondria which does not require the signal sequence, electro-chemical potential, and general protein translocation machinery [Marcher et al. (1995) /. Biol. Chem. 270, 12390-12397].
  • Mitochondria have been implicated in apoptosis since the discovery that the bcl-2 family of proteins are located in the outer mitochondrial membrane [Monaghan et al. (1992) supra; Krajewski et al. (1993) supra; de Jong et al. (1994) supra].
  • In vitro apoptosis in Xenopus egg extracts requires a dense organelle fraction enriched in mitochondria [Newmeyer et al. (1994) supra].
  • the present inventors have shown that purified mitochondria from hamster heart can supplement cytosol immunodepleted of cytochrome c, or cytosol prepared in the presence of sucrose to support CPP32 activating reaction.
  • cytochrome c is a necessary component of cellular apoptotic program indicates that mitochondria are involved in apoptosis by releasing cytochrome c. Because cytochrome c is encoded by a nuclear gene and translocation of apocytochrome c into mitochondria does not require membrane potential and general protein translocation machinery [Evans and Sca ⁇ ulla (1988) supra; Mayer et al. (1995) supra], it can be totally functional in apoptosis in cells lacking mitochondrial DNA. Consistent with this model, the cells undergoing apoptosis induced by staurosporine showed increased cytosolic cytochrome c. Release of cytochrome c into the cytosol provides a target for regulation of apoptosis, possibly by the bcl-2 family of proteins.
  • Monoclonal or polyclonal antibodies preferably monoclonal, specifically reacting with a target protein can be made by methods known in the art. See, e.g., Harlow and Lane (1988) Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratories; Goding (1986) Monoclonal Antibodies: Principles and Practice, 2d ed., Academic Press, New York; and Ausubel et al. (1987) supra. Standard techniques for cloning, DNA isolation, amplification and purification, for enzymatic reactions involving DNA ligase, DNA polymerase, restriction endonucleases and the like, and various separation techniques are those known and commonly employed by those skilled in the art. A number of standard techniques are described in Sambrook et al.
  • Nucleotide triphosphates were purchased from Pharmacia (Piscataway, NJ).
  • ADP, dADP, AMP, dAMP, adenosine and deoxyadenosine were from ICN Biomedicals, Inc. (Costa Mesa, CA).
  • Pepstatin A, leupeptin, N-acetyl-leucyl-leucyl-norleucine (ALLN) were obtained from Boehringer Mannheim Co ⁇ oration
  • Silver staining was carried out using a Silver Stain Plus kit from Bio-Rad Laboratories (Hercules, CA). Plasmids were purified using a Megaprep kit (Qiagen, Chatsworth, CA).
  • Human HeLa S3 cells were grown as described [Wang et al. (1993) J. Biol. Chem. 268, 14497-14504]. The cells (5 x 10 5 /ml) were harvested by centrifugation at 1,800 x g for 10 min at 4°C.
  • the cell pellet was suspended in 5 volumes of ice-cold buffer A [20 mM Hepes-KOH, pH 7.5, 10 mM KC1, 1.5 mM MgCl 2 , 1 mM sodium EDTA, 1 mM sodium EGTA, 1 mM dithiothreitol (DTT) and 0.1 mM PMSF] supplemented with protease inhibitors (5 ⁇ /ml pepstatin A, 10 ⁇ g/ml leupeptin, 2 ⁇ gml aprotinin, and 25 ⁇ g/ml ALLN).
  • protease inhibitors 5 ⁇ /ml pepstatin A, 10 ⁇ g/ml leupeptin, 2 ⁇ gml aprotinin, and 25 ⁇ g/ml ALLN).
  • the cells were disrupted by douncing 15 times in a 100 ml Kontes douncer with the B pestle (Kontes Glass Co., Vineland, NJ).
  • the nuclei were centrifuged at 1000 x g for 10 min at 4°C.
  • the supernatant was further centrifuged at 10 5 x g for 1 hr in a Beckman SW 28 rotor.
  • the resulting supernatant (S-100 fraction) was stored at -80 °C and used for the in vitro apoptosis assay and the starting material for the purification of Apaf-2.
  • 293 cells were set up at 5 x 10 5 cells per 100 mm dish in medium A [Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% (v/v) heat-inactivated fetal calf serum, 100 U/ml penicillin and 100 ⁇ g/ml streptomycin sulfate]. After incubation for 48 hr at 37 °C in a 5 % C0 2 incubator, the cells were harvested, collected by centrifugation (1000 g, 10 min, 4°C).
  • DMEM Dulbecco's modified Eagle's medium
  • U937 cells were set up at 5 x 10 5 cell/ml in medium B [RPMI 1640 medium supplemented with 10% fetal calf serum, 100 U/ml penicillin and 100 ⁇ g/ml streptomycin sulfate] . After incubation for 48 hr in a 5% C0 2 incubator, the cells were collected by centrifugation (1000 g, 10 min, 4°C). The cell pellets of 239 cell and U937 cell were washed once with ice- cold PBS and resuspended in 5 volumes of ice-cold buffer A supplemented with protease inhibitors. After holding on ice for 15 min, the cells were broken by passing 15 times through a G22 needle.
  • medium B RPMI 1640 medium supplemented with 10% fetal calf serum, 100 U/ml penicillin and 100 ⁇ g/ml streptomycin sulfate
  • a PCR fragment encoding amino acids 29-277 of hamster CPP32 [Wang et al. (1996) supra] was cloned into Ndel and BamHI sites of pET 15b vector (Novagen, Madison, WI).
  • the resulting fusion protein of six histidines with hamster CPP32 (amino acids 29-277) was translated in a TNT T7 transcription/translation kit (Promega, Madison, WI) in the presence of 35 S-methionine according to the manufacturer's instructions.
  • the translated protein was passed through a 1 ml nickel affinity column (Qiagen, Chatsworth, CA) equilibrated with buffer A. After washing the column with 10 ml of buffer A, the translated CPP32 was eluted with buffer A containing 250 mM imidazole.
  • Human SREBP-2 was translated in a TNT SP6 transcription/translation kit as described [Wang et al. (1995) [Hua et al. (1993) Proc. Natl. Acad. Sci. USA 90, 11603-11607] . Full length human PARP cDNA [Cherney et al. (1987) Proc. Natl. Acad. Sci.
  • a monoclonal antibody against human CPP32 was purchased from Transduction Laboratories and a monoclonal antibody against cytochrome c (7H8.2C12) was obtained as described previously [Jemmerson and Johnson (1991) Proc. Natl. Acad. Sci. USA 88, 4428-4432]. Monoclonal antibody specific for cytochrome c is available from Phar ⁇ ngen. Immunoblot analysis was performed with horseradish peroxidase-conjugated anti- mouse immunoglobulin G using the Enhanced Chemiluminescence (ECL) Western Blotting Detection reagents (Amersham Co ⁇ oration, Arlington Heights, IL).
  • ECL Enhanced Chemiluminescence
  • CPP32 was translated and purified as described above. Aliquot of 3 ⁇ l of the in vitro translated CPP32 was incubated with the indicated protein fraction, nucleotides, and 1 mM additional MgCl 2 at 30°C for 1 hour in a final volume of 20 ⁇ l of buffer A. At the end of the incubation, 7 ⁇ l of 4x SDS sample buffer was added to each reaction. After boiling for 3 min, each sample was subjected to a 15 % SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The gel was transferred to a nitrocellulose filter which was subsequently exposed to a Kodak X-OMAT AR X-ray film (Eastman Kodak, Rochester, NY) for 16 hr at room temperature.
  • SDS-PAGE SDS-polyacrylamide gel electrophoresis
  • Example 6 Purification of Apaf-2 from HeLa S-100 All purification steps were carried out at 4°C. All the chromatography steps except the phosphocellulose column were carried out using an automatic fast protein liquid chromatography (FPLC) station (Pharmacia, Piscataway, NJ).
  • FPLC automatic fast protein liquid chromatography
  • the eluate was loaded onto a Superdex-200 gel filtration column (Pharmacia, Piscataway, NJ) (300 ml) equilibrated with buffer A and eluted with the same buffer. Fractions of 10 ml were collected and assayed for Apaf-2 activity. The active fractions from the gel- filtration column were pooled and loaded onto an anion exchange Mono Q 5/5 column and a cation exchange Mono S 5/5 column connected together. The columns were pre-equilibrated with Buffer A.
  • Livers from 4 male Golden Syrian hamsters were rinsed with ice-cold phosphate-buffered saline (PBS) and homogenized in 0.25 g/ml of buffer B (10 mM Hepes-KOH, pH 7.6, 2.4 M sucrose, 15 mM KC1, 2 mM sodium EDTA, 0.15 mM spermine, 0.15 mM spermidine, 0.5 mM DTT, 0.5 mM PMSF) by three strokes of a motor-driven homogenizer. The homogenates were centrifuged through a 10-ml cushion of buffer
  • the DNA in the supernatant was precipitated with an equal volume of 100% (v/v) ethanol.
  • the DNA precipitate was washed once with 70% ethanol and resuspended in 40 ⁇ l of buffer E containing 10 mM Tris-HCl, pH 7.5, 1 mM sodium EDTA, and 200 ⁇ g/ml DNAse-free RNase A (Worthington Biochemical Co ⁇ oration, Freehold, NJ). After incubation at 37 °C for 2 hr, the DNA was loaded onto a 2% agarose gel and electrophoresis was conducted at 50 V for 2 hr in 0.5 x TBE buffer (1 x TBE buffer contains 90 mM Tris- borate/2 mM EDTA). The gel was stained with 2 ⁇ g/ml ethidium bromide for 15 min, destained with water for 1 hr, and the DNA was visualized using UV light.
  • Example 9 Immunodepletion of Cytochrome c from HeLa S-100
  • the beads were washed once with 1 ml of buffer A and incubated with 1.5 ml S-100 fractions for 5 hr in a rotator at 4°C. The beads were subsequently pelleted by centrifugation for 15 min in a microcentrifuge at 4°C. The supernatant was used as S-100 immunodepleted of cytochrome c.
  • S-100 was prepared from 20-liters of HeLa cells in spinner culture as described in the Examples. An aliquot of each fraction was dialyzed against buffer A and the Apaf-2 activity was assayed by recombining with 35 S- labeled CPP32 at four concentrations of protein. The results were quantified by phosphorimaging.
  • Xaa lie lie Xaa Gly Glu Asp Thr Leu Met Glu Tyr Leu 1 5 10

Abstract

L'invention propose un système acellulaire fondé sur le cytosol de cellules à croissance normale qui reproduit les aspects mesurables du programme d'apoptose. Le programme d'apoptose est déclenché par l'addition de dATP dans un échantillon approprié de surnageant de HeLa à 100 000 g. Le fractionnement du cytosol permet d'obtenir une protéine de 15 kDa, que l'on identifie par son spectre d'absorption et par sa séquence protéique comme le cytochrome c, nécessaire à l'apoptose in vitro. L'élimination du cytochrome c du cytosol par déplétion immunitaire ou par inclusion de saccharose dans le but de stabiliser la mitochondrie lors de la préparation du cytosol diminue l'activité d'apoptose. L'adjonction d'un cytochrome c exogène à des extraits appauvris en cytochrome c relance l'activité d'apoptose. Les cellules où se produit l'apoptose in vivo manifestent une libération accrue de cytochrome c vers leur cytosol, ce qui laisse à supposer que la mitochondrie peut fonctionner en apoptose en libérant le cytochrome c.
PCT/US1997/012090 1996-07-12 1997-07-11 Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere WO1998002579A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP97933393A EP0918882A1 (fr) 1996-07-12 1997-07-11 Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere
JP50617298A JP2001526525A (ja) 1996-07-12 1997-07-11 アポトーシスの調節とその研究のためのインビトロモデル
AU36587/97A AU727222B2 (en) 1996-07-12 1997-07-11 Regulation of apoptosis and in vitro model for studies thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1226896P 1996-07-12 1996-07-12
US60/012,268 1996-07-12

Publications (2)

Publication Number Publication Date
WO1998002579A1 WO1998002579A1 (fr) 1998-01-22
WO1998002579A9 true WO1998002579A9 (fr) 1998-04-30

Family

ID=21754150

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/012090 WO1998002579A1 (fr) 1996-07-12 1997-07-11 Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere

Country Status (2)

Country Link
CA (1) CA2260766A1 (fr)
WO (1) WO1998002579A1 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1077724A2 (fr) * 1998-04-17 2001-02-28 The University Of Vermont Methodes et produits concernant les interactions metaboliques dans les maladies
US7381413B1 (en) 1998-04-17 2008-06-03 University Of Vermont And State Agricultural College Methods and products related to metabolic interactions in disease
AU2004201144B2 (en) * 1998-04-17 2006-04-27 University Of Vermont And State Agricultural College Methods and products related to metabolic interactions in disease
US6391575B1 (en) 1999-03-05 2002-05-21 Idun Pharmaceuticals, Inc. Methods for detecting membrane derived caspase activity and modulators thereof
AU780815B2 (en) 1999-06-23 2005-04-21 University Of Vermont And State Agricultural College, The Methods and products for manipulating uncoupling protein expression
WO2001035093A1 (fr) 1999-11-08 2001-05-17 Eisai Co. Ltd. Methode de detection de la mort cellulaire, et reactif de detection
EP1205540A1 (fr) 2000-11-10 2002-05-15 Evotec OAI AG Procédé pour déterminer la vitalité de cellules
US7138239B2 (en) 2001-05-09 2006-11-21 Eisai Co., Ltd. Method and reagent for testing for multiple organ failure in SIRS by cytochrome C measurement
US7510710B2 (en) 2004-01-08 2009-03-31 The Regents Of The University Of Colorado Compositions of UCP inhibitors, Fas antibody, a fatty acid metabolism inhibitor and/or a glucose metabolism inhibitor
WO2006112445A1 (fr) * 2005-04-15 2006-10-26 Eisai R & D Management Co., Ltd. Procede et reactif de determination immunochimique du cytochrome c

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5550019A (en) * 1993-05-26 1996-08-27 La Jolla Cancer Research Foundation Methods of identifying compounds which alter apoptosis

Similar Documents

Publication Publication Date Title
Liu et al. Induction of apoptotic program in cell-free extracts: requirement for dATP and cytochrome c
EP0906434B1 (fr) CODAGE DES APOTOSE PROTEASES Mch4 ET Mch5 PAR DES ACIDES NUCLEIQUES, ET METHODES D'UTILISATION
CA2412635A1 (fr) Nouvelles proteases
CA2399727A1 (fr) Nouveaux homologues de type subtilase (narc-1)
WO1998002579A9 (fr) Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere
WO1998002579A1 (fr) Regulation de l'apoptose et modele in vitro destine a des recherches en la matiere
Mahoney et al. The human homologue of the yeast polyubiquitination factor Ufd2p is cleaved by caspase 6 and granzyme B during apoptosis
AU676721B2 (en) Role of ATP-ubiquitin-dependent proteolysis in MHC-1 restricted antigen presentation and inhibitors thereof
US6558900B2 (en) Regulation of apoptosis and in vitro model for studies thereof
US6686459B1 (en) Mch3, a novel apoptotic protease, nucleic acids encoding and methods of use
AU727222B2 (en) Regulation of apoptosis and in vitro model for studies thereof
PL193394B1 (pl) Sekwencja DNA, jej zastosowanie, wektor i jego zastosowanie, transformowana komórka, polipeptyd o aktywności białka G1 i sposoby jego wytwarzania, izolowania i identyfikowania, oraz jego zastosowanie, sposoby modulowania działania liganda FAS-R lub TNF in vitro, sposoby przesiewowego badania liganda i sekwencji DNA kodującej ten ligand, sposoby jego identyfikacji wytwarzania oraz izolowania i kompozycja farmaceutyczna
US5851815A (en) MCH4 and MCH5, apoptotic proteases
US6566505B2 (en) Antibodies to Mch6 polypeptides
JP2000511781A (ja) アポトーシスを調節する方法および試薬
US7247438B1 (en) Methods of identifying agents which enhance caspase activity
US6515118B1 (en) DNA fragmentation factor
US20020086401A1 (en) Novel cyclin-selective ubiquitin carrier polypeptides
JP5085570B2 (ja) Ｍｃｈ４およびＭｃｈ５、アポトーシス性プロテアーゼ、コードする核酸、および使用方法
Liu Biochemical dissection of an apoptotic program in mammalian cells
WO2004028342A2 (fr) Granzyme b endogene dans des cellules non hematopoeitiques humaines