干细胞之家 - 中国干细胞行业门户第一站

标题: Protein synthesis persists during necrotic cell death [打印本页]

作者: kato    时间: 2009-3-6 09:49     标题: Protein synthesis persists during necrotic cell death

1 Molecular Signalling and Cell Death Unit, Department for Molecular Biomedical Research, Flanders Interuniversity Institute for Biotechnology (VIB) and Ghent University, B9052 Ghent, Belgium$ T2 V* [. ~8 D: ~/ y) C# R
: t+ w% B! \# @$ b' J+ F
2 Microscopy Core Facility, Department for Molecular Biomedical Research, Flanders Interuniversity Institute for Biotechnology (VIB) and Ghent University, B9052 Ghent, Belgium
$ s% [# f7 g; I3 S4 \5 d$ x# R& |" I: u5 W1 A$ B
3 Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, Netherlands$ s3 h# i2 F/ Q/ N

& I5 m5 w' ~8 rAbstract
& _' y- |6 v* R: T$ z1 v$ r3 l. P7 d- Y" _
Cell death is an intrinsic part of metazoan development and mammalian immune regulation. Whereas the molecular events orchestrating apoptosis have been characterized extensively, little is known about the biochemistry of necrotic cell death. Here, we show that, in contrast to apoptosis, the induction of necrosis does not lead to the shut down of protein synthesis. The rapid drop in protein synthesis observed in apoptosis correlates with caspase-dependent breakdown of eukaryotic translation initiation factor (eIF) 4G, activation of the double-stranded RNA-activated protein kinase PKR, and phosphorylation of its substrate eIF2-. In necrosis induced by tumor necrosis factor, double-stranded RNA, or viral infection, de novo protein synthesis persists and 28S ribosomal RNA fragmentation, eIF2- phosphorylation, and proteolytic activation of PKR are absent. Collectively, these results show that, in contrast to apoptotic cells, necrotic dying cells retain the opportunity to synthesize proteins.
2 K9 N1 r: I8 t- s: i8 q; `- r0 ^' C: ^! n) d1 g' H
M. Kalai's present address is Unit of Molecular Microbiology, Institute Pasteur of Brussels, B1180 Brussels, Belgium.
5 M! I0 j. Z/ b1 Z( n% W. D+ D4 @# R
Abbreviations used in this paper: CHX, cycloheximide; CVB, coxsackievirus B; dsRNA, double-stranded RNA; eIF, eukaryotic translation initiation factor; FADD, Fas-associated death domain; JE, Jurkat E; PARP, poly(ADP-ribose) polymerase; PI, propidium iodide; PKR, dsRNA-activated protein kinase; RIP1, receptor interacting serine/threonine protein kinase 1; ROS, reactive oxygen species; rRNA, ribosomal RNA; zVAD-fmk, benzyloxycarbonyl-Val-Ala-DL-Asp(OMe)-fluoromethylketone.* ]/ N# k: b/ g* ?9 C4 g
) ?/ w4 |( v* L6 I
Introduction
$ ^- }! B7 v& A7 {! O/ i! D1 {, p  B% j% R* V" r
Cell death is an essential part of metazoan development, homeostasis, and mammalian immune regulation. Based on the typical morphological features that become apparent in the course of cellular demise, three major types of cell death have been discerned: apoptosis, autophagic cell death, and necrosis (Schweichel and Merker, 1973; Clarke, 1990). The characteristic features of apoptosis, such as blebbing of the cell membrane, condensation of the nucleus, and internucleosomal cleavage of DNA, are a direct or indirect consequence of the activation of caspases (Hengartner, 2000; Lamkanfi et al., 2002). Autophagic cell death is characterized by extensive autophagy and appears in development as well as in pathological conditions such as Parkinson's disease and muscle diseases (Levine and Klionsky, 2004). The most prominent feature of necrosis is swelling (oncosis) of the cell and its organelles followed by loss of cell membrane integrity. Necrosis has often been considered as a passive process, lacking underlying signaling events. This assumption might hold for cell death resulting from severe physical or environmental damage such as hyperthermia or dounce- and detergent-induced lysis. However, necrotic cell death also occurs in normal physiological settings such as intestinal epithelium homeostasis (Barkla and Gibson, 1999). Necrosis is observed in various pathophysiological conditions such as cardiac ischemia and diseases associated with neuronal cell death such as stroke, amyotrophic lateral sclerosis, and Alzheimer's, Huntington's, and Parkinson's diseases (Colbourne et al., 1999; Nicotera et al., 1999). Furthermore, when caspase activation is prevented, necrosis can substitute for canonical caspase-dependent apoptosis induced by, for example, TNF, TNF-related apoptosis-inducing ligand, Fas ligand, and double-stranded RNA (dsRNA; Vercammen et al., 1998; Kalai et al., 2002; Vanden Berghe et al., 2003) and during digit formation in the developing mouse embryo (Chautan et al., 1999).( I$ n5 T$ q- z7 I

* ?- P, e$ e1 I6 v" ]# u/ r6 F) PConvincing evidence for the existence of a programmed necrotic pathway was reported by Holler et al. (2000), who demonstrated that death domain receptor–induced necrosis of human T lymphocytes requires functional receptor interacting serine/threonine protein kinase 1 (RIP1). Dimerization of Fas-associated death domain (FADD) induces necrosis in caspase-8–deficient Jurkat T cells (Kawahara et al., 1998) and in the mouse L929 fibrosarcoma cell line in a RIP1-dependent way (Vanden Berghe et al., 2004). In line with this finding, RIP1- and FADD-deficient mouse embryonic fibroblasts prove resistant to necrosis induced by TNF in the presence of the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-DL-Asp(OMe)-fluoromethylketone (zVAD-fmk; Lin et al., 2004). Nevertheless, insight in the molecular events that operate during necrosis is still limited.
+ P( y7 ~# B3 b
+ f6 ^/ n0 o/ l" z" s& aInduction of apoptosis is characterized by a general inhibition of protein synthesis that is attributed to the proteolytic attack of translation initiation factors (Clemens et al., 2000). Because the effect of necrotic cell death on the translational machinery has not been examined, we compared the protein synthesis capacity of cells subjected to apoptotic or necrotic death stimuli. We show that after necrosis, protein synthesis is sustained in the dying cell, up to the point where the cell loses its membrane integrity.
7 F% k, y/ n, Y- B  `0 c, [" \7 [9 c$ ]
Results and discussion
* w6 J+ g. {6 E( u
( j$ X# I& l/ B; ^4 XdsRNA and TNF induce necrosis in Jurkat T cell clones
! t: H5 w0 d6 w( y- R9 r
: U+ E. X) x6 l+ C8 f8 i% CTo test if protein synthesis is disturbed during a necrotic response, we made use of three different Jurkat T cell lines. Wild-type cells (Jurkat E [JE]) respond to Fas-ligation by apoptosis and were used as control. As a first model of necrosis we chose dsRNA treatment of JB6 cells. These cells, genetically deficient in caspase-8 and overexpressing Bcl-2, die in a necrotic way in response to dsRNA, unlike JE cells, which hardly respond to dsRNA (Kalai et al., 2002). In a second model, we used death receptor–induced necrosis of FADD-deficient cells stimulated with TNF (TNF was used because, in our hands, Fas-ligation in the absence of caspase-8 or FADD or in the presence of caspase inhibitors barely induced necrosis). As expected, JE cells treated with agonistic anti-Fas antibody displayed blebbing of the cell membrane and little or no propidium iodide (PI) staining at the early stage of apoptosis (Fig. 1 A). Treatment of JB6 cells with dsRNA or of FADD-deficient cells with TNF induced swelling of the cells, followed by cellular collapse and loss of membrane integrity. To further differentiate between cell death types, the generation of reactive oxygen species (ROS) was assessed. An increase in ROS production was detected starting 2–4 h after stimulation in necrotic but not in apoptotic cells (Fig. 1 B). Finally, the caspase inhibitors zVAD-fmk and qVD-OPH failed to prevent necrotic cell death (Fig. 1 C).
9 x" t* r2 k) t8 F, v0 d4 V
! k0 |/ }# J! Q; qThe rate of protein synthesis remains constant during necrosis! X( F( d8 D  c8 M) ]4 K
/ Q$ O, H! d+ U4 ]& h$ m
To compare de novo protein synthesis in the course of apoptosis and necrosis, cells were pulse-labeled with 35S-methionine at various time points after induction of cell death. In agreement with previous reports, induction of apoptosis in JE cells resulted in a rapid decrease in de novo protein synthesis that was already apparent 2 h after treatment with agonistic anti-Fas antibody (Fig. 2 A and Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200407162/DC1). In contrast, the rate of protein synthesis in JB6 cells treated with dsRNA and in FADD-deficient cells exposed to TNF was not affected up to 8 h after treatment, when the majority of the cells had already lost membrane integrity. The kinetics of cell death, determined by the loss of membrane integrity, were similar in the apoptotic and necrotic settings (Fig. 2 A). We conclude that necrosis induced by dsRNA or TNF in Jurkat cells does not affect the overall protein synthesis capacity of the cells destined to die. Pulse-labeling experiments of mouse L929 cells stimulated to die necrotically or apoptotically confirmed that the rate of protein synthesis is not overtly affected in necrosis, whereas translation is rapidly shut down in apoptosis (Fig. 2 B).. l. y4 m8 \# C9 k

; {: w8 R  ]6 @' _9 L3 sThe protein synthesis machinery remains intact during necrosis
% C$ n5 ?0 T/ h: i. M9 j* v/ ]5 u: R& W
The initiation phase of protein synthesis constitutes the major site of its regulation. Eukaryotic translation initiation factor (eIF) 4G is a prime determinant in eukaryotic translation initiation because it provides the molecular bridge between the mRNA and the ribosome (Pestova et al., 2001). Caspase-dependent as well as caspase-independent cleavage of eIF4G has been reported and this event correlates with the shut down of protein synthesis (Clemens et al., 2000). Because protease activity may contribute to necrosis, we assessed the integrity of eIF4G by immunoblotting. In cells treated with anti-Fas, a 45-kD fragment of eIF4G was clearly detected (Fig. 3 A). In contrast, no generation of eIF4G fragments in dsRNA- or TNF-induced necrosis was found. Next, we examined the modification of translation initiation factor eIF2- in apoptotic and necrotic cells. eIF2- is a subunit of the heterotrimeric eukaryotic translation initiation factor eIF2, which mediates the binding of initiator Met-tRNAi to the 40S ribosomal subunit. eIF2- phosphorylation leads to translation inhibition and in apoptosis coincides with caspase-dependent cleavage and activation of the eIF2- kinase dsRNA-activated protein kinase (PKR; Saelens et al., 2001). eIF2- phosphorylation increased 2 h after anti-Fas treatment, coinciding with eIF4G cleavage, PKR cleavage, and the drop in the rate of translation (Figs. 2 A and 3 A). No PKR cleavage or significant eIF2- phosphorylation was observed in either necrotic system. DsRNA is a potent activator of PKR, and extracellularly administered poly-inosinic-cytidylic acid can activate PKR in a TRIF (TIR domain-containing adaptor inducing IFN-)-dependent manner (Hsu et al., 2004). The lack of PKR activation in JB6 cells exposed to dsRNA is somewhat surprising. It is possible that the TLR3 pathway in JB6 cells, which have a strong antiapoptotic constellation (overexpression of Bcl-2 and lack of caspase-8), favors RIP1-mediated necrosis (Kalai et al., 2002), a condition that may interfere with PKR activation.* ]# z% z% `; a2 i

* g$ W% c% b% r  _$ Z1 c( gCleavage of 28S ribosomal RNA (rRNA) in a caspase-dependent or -independent way has been shown to correlate with inhibition of protein synthesis in cell death, and therefore was also analyzed (Houge et al., 1995). Apoptotic cells displayed two distinct RNA bands reportedly derived from 28S rRNA (Fig. 3 B; Houge et al., 1995). In contrast, the induction of necrosis by dsRNA treatment of JB6 cells and by TNF treatment of FADD-deficient cells did not generate detectable rRNA alterations, which is in line with the ability of the cell to maintain protein synthesis (Fig. 3 B).
+ ^8 B! N0 m" T4 a
, A; ^1 G2 n4 k: t' j# y( {Necrosis in wild-type Jurkat cells
$ B) o7 V8 b9 ~' Z* g& P
$ R% H9 H5 `5 n7 B4 QTo ascertain the physiological relevance of necrosis in wild-type JE, we monitored cell death induced by a nonenveloped, cytolytic virus. We found that coxsackievirus B (CVB), an enterovirus belonging to the Picornaviridae family, induces necrosis-like cell death in both JE and JB6 cells. CVB replicated efficiently in both cell lines and induced swelling of the cells followed by loss of membrane integrity (Fig. 4, A and B). Virus-induced cell death, which became apparent 6 h after infection, proceeded without caspase activity or poly(ADP-ribose) polymerase (PARP) cleavage (Fig. 4, C, D, and F). CVB infection had little, if any, effect on protein synthesis in both cell lines (Fig. 4 E). eIF4G analysis showed the generation of a 100-kD COOH-terminal fragment (Fig. 4 F), an event that is typically observed in enterovirus-infected cells (Etchison et al., 1982) and that has been implicated in the virus-induced switch from cap-dependent host cell translation to IRES-driven translation of the viral genome (Ehrenfeld, 1982). The morphology of the dying cells and the absence of caspase activation strongly indicate that even apoptosis-competent cells can die by necrosis, e.g., following a viral infection. Finally, we also analyzed the effect of an apoptotic and a necrotic stimulus on CVB replication. We found that anti-Fas treatment of infected JE cells suppresses translation and viral progeny by 10-fold (Fig. 5, A and C). In contrast, enhancing necrosis by dsRNA treatment of infected JB6 cells did not affect translation or CVB propagation (Fig. 5, B and D). This finding provides evidence that CVB can efficiently propagate in translationally active cells dying of necrosis but not in apoptotic cells in which protein synthesis is blocked.
6 Y  t+ z. I8 a: \& _% L( ?3 m- D" r. W; [1 }
Physiological implications of ongoing translation in necrosis% W0 O2 p  t0 C: p0 \
. E7 \. x$ [$ D/ p* w' W1 H
Our results demonstrate that necrosis induced by dsRNA or TNF treatment of Jurkat T lymphocytes and by TNF in L929 fibrosarcoma cells does not affect the protein synthesis rate. DsRNA and TNF give rise to a rapid and strong induction of gene expression as evidenced by the phosphorylation status of p38 MAPK (unpublished data). In a cell destined to die by necrosis, translation of newly synthesized transcripts could still occur, resulting for example in gene products that may alert other cells in a local or systemic fashion. Apoptosis is often considered as a "clean death" because it prevents the release of the intracellular content of the cell. Rapid inhibition of translation may contribute to keep apoptotic cell demise immunologically silent. Moreover, apoptosis can be considered as an antiviral host cell response aimed at curtailing virus replication. In contrast, necrotic cell death and spilling of the intracellular content into the extracellular environment can trigger inflammation by providing "danger" signals for the surrounding cells and immune competent cells, such as dendritic cells, granulocytes, and monocytes (Sauter et al., 2000). However, at the same time, viruses, which often use strategies to modulate the apoptotic program, may profit from the available translation apparatus in the necrotic cell to propagate until the cell eventually demises./ P3 Q! r6 Q8 g; X! D" |

1 d/ d# `$ T  SMaterials and methods1 X1 E- X8 J# @) _1 O8 N2 O

& w! k% V0 q/ ICell culture and induction of apoptosis or necrosis
: A4 B+ A" r3 D% a+ s: }# ]9 {1 U# w
0 j6 }1 c' ?  [Jurkat T cells were grown as described previously (Kalai et al., 2002). Parental E cells and JB6 cells were provided by S. Nagata (Osaka University Medical School, Osaka, Japan). FADD-deficient cells were provided by J. Blenis (Harvard Medical School, Boston, MA). 100 ng/ml CH-11 anti-Fas antibody (BioCheck) was used to induce apoptosis in JE cells. 50 μg/ml dsRNA (poly (I)-poly(C)) (Amersham Biosciences) and 5000 IU/ml of human TNF were used to induce necrosis in JB6 and FADD-deficient cells, respectively. Caspases were blocked by incubating cells for 30 min with 25 μM zVAD-fmk (Bachem) or quinoline-Val-Asp-O-phenoxy (MP Biomedicals) before stimulation. Cell death was monitored by trypan blue exclusion or by measuring PI (15 μM) uptake at 610 nm by FACS analysis using a FACScalibur flow cytometer (Becton Dickinson) equipped with a 488-nm Argon laser. ROS production was measured as the fluorescence at 525 nm of rhodamine 123, resulting from oxidation of dihydrorhodamine 123 (Molecular Probes) in PI-negative cells. Dihydrorhodamine 123 was applied to the cells at 0.1 μM 30 min before analysis. Relative fluorescence values are depicted as the ratio between the fluorescent signal at a given time point and the initial fluorescence for the same condition, using mean fluorescence values from a representative experiment performed in triplicate. Caspase activity was determined as described using DEVD-amc as substrate (Saelens et al., 2001).
. z9 A6 m5 G" R( A
. c. X- s) z+ M9 }( ^% yMicroscopic analysis
+ Q6 A9 _! H1 M1 ?/ Y+ j& F* A, z8 m! E
Cells were seeded in normal growth medium in 8-chambered cover glass (Nunc) and treated for the time indicated in the legends of Figs. 1 and 4. Phase-contrast images and fluorescence images were photographed using a microscope (model DM IRE2; Leica) equipped with a HCX PLAPO 63x/1.30 glycerine corrected 37°C lens and a coolsnap HQ camera. The camera is controlled by the ASMDW acquisition software (Leica). PI (1 μM) fluorescence was monitored at 540 nm using a 50-W Xe lamp for excitation. Blind deconvolution of the fluorescence and overlay images was performed using Metamorph 5.0 software.
& z3 c2 M/ `; G4 [* X
9 t6 f. R9 U2 l* X  fMetabolic labeling of proteins
" L1 B. Z1 B' \/ d3 q- W' \! ]
9 T* t/ R4 ]8 `" v7 q  M4 b6 NTo avoid stress responses, metabolic labeling of the cells was performed in normal growth medium. 16 h before labeling, cells were seeded at 106 cells/ml. At selected time points after stimulation, samples of 1.5 x 106 cells were transferred to a 6-well plate and labeled for 30 min with 10 μCi of Trans35S-label (MP Biomedicals). 10 μg/ml cycloheximide (CHX) was added to cells 1 h before labeling. After pulse labeling, cells were washed twice with ice-cold PBS and lysed on ice with caspase lysis buffer containing 10 mM Tris-HCl, pH 7.5, 200 mM NaCl, 5 mM EDTA, 10% glycerol, 1% NP-40, 1 mM aprotinin, 1 mM leupeptin, and 100 μM PMSF. From each time point, 30 μg of protein from the 14,000 g supernatant fraction was resolved by SDS-PAGE and visualized by Coomassie brilliant blue staining. The intensity of the Coomassie-stained bands in each lane was quantified by densitometry. After drying, 35S signals from the gels were captured and quantified using a PhosphorImager (Bio-Rad Laboratories).9 V9 ~* K% ]8 d8 c, T- W

6 {8 v" [0 t% D+ I; A0 V$ JImmunoblot analysis2 Q6 o( o* V8 W' X, s/ m

; O- J0 K3 x( i0 zProtein extracts from cell lines were prepared by lysis with sample buffer, separated in 12.5% SDS-PAGE gels, and transferred to nitrocellulose. Antibodies against the following antigens were used to probe the blots: eIF4G and PKR (Transduction Laboratories), phosphorylated eIF2- (Research Genetics), eIF2- (Santa Cruz Biotechnology, Inc.), PARP (BIOMOL Research Laboratories, Inc.), phosphorylated-p38 MAPK (Biosource International), and total p38 MAPK (Cell Signaling Technology). Immuno-reactive proteins were visualized using chemiluminescence and signals were captured by exposure to film (Amersham Biosciences). Bands on the luminographs were quantitated by densitometry using a Lumi-Imager workstation (Roche Molecular Biochemicals).
1 J7 c/ X4 F/ H, m0 U" A. R2 j* T
7 M4 O$ A  g/ s6 q4 m4 D5 fAnalysis of rRNA6 Y$ U7 @4 u7 g% @, P
5 T( D+ Y4 D' c, X, ^! J
6 and 7 h after induction of apoptosis and necrosis, total RNA was prepared using an RNeasy kit (QIAGEN). 10 μg of RNA was separated in an agarose gel, using Tris-Borate-EDTA as running buffer, and stained with ethidium bromide.4 j5 [1 Q7 E$ o3 |
; ]2 H! B- B2 o% ^) k9 _- V
Viral infection6 V6 t: Q  }6 z6 F8 Q# j
8 b7 i+ z7 D$ w- L. w) A( w' K
CVB used in this study was derived from plasmid pCB3/T7, containing a cDNA of coxsackievirus type B3 (strain Nancy) behind a T7 RNA polymerase promoter. Viruses were grown and titrated on Buffalo green monkey kidney cells. Jurkat cells were infected for 1 h at 37°C at a multiplicity of infection of 20 TCID50 (50% tissue culture infective dose) per cell. Hereafter, cells were washed and incubated at 37°C for further analysis at the indicated time periods. Viruses were extracted from the Jurkat cells by three cycles of freeze thawing and titrated on Buffalo green monkey kidney cells.
3 l/ \6 h& D9 J0 _$ h$ P/ U! a9 Y( o6 r( E
Online supplemental material
( {% P: d, F$ U, O
. u8 \, L- f# x" A: bFig. S1 shows that translation is rapidly shut down in apoptosis but not in necrosis. Online supplemental material is available at http://www.jcb.org/cgi/content/full/jcb.200407162/DC1.& f, M5 U6 I- |8 |- W

' L; r$ ~, z5 _& \4 X* xAcknowledgments: q* c" s. y$ s$ W) F& r) t# C

* u+ V! |' e5 n/ }" rWe thank A. Bredan for editorial help. We are grateful to S. Nagata and J. Blenis for the caspase-8 and FADD-deficient Jurkat cells.
9 O' Q: E& i' D( i6 U, |9 R# q
7 t7 N6 R5 }# w" r3 n5 i3 ?This work was supported by the Interuniversitaire Attractiepolen-V (IUAP-V), Fonds voor Wetenschappelijk Onderzoek-Vlaanderen (grants 3G.0006.01 and 3G.021199), Belgian Federation against Cancer, European Community Research, Technological Development and Demonstration (EC-RTD; grant QLG1-CT-1999-00739), Ghent University cofinancing EU project (011C0300), and Geconcerteerde Onderzoeksacties (GOA) project (12050502). X. Saelens is supported by GOA project 12050502, N. Festjens by Instituut voor de aanmoediging van Innovatie door Wetenschap en Technologie in Vlaanderen and IUAP-V, M. Kalai by EC-RTD, and F. van Kuppeveld by grants from the Netherlands Organization for Scientific Research (NWO-VIDI 917.46.305) and the Beijerink Premie (2004).
4 q3 ^8 L/ e9 Y2 p2 h3 T% @% r; y
! t9 a' [5 r5 o' P: i* |0 d; sReferences
& f# X% @8 F' k: Z# B8 a* }' g% u/ h  X& K9 ?1 Q2 a
Barkla, D.H., and P.R. Gibson. 1999. The fate of epithelial cells in the human large intestine. Pathology. 31:230–238.6 ^. a! i2 X, C3 j% ]+ {
; \0 ~  u3 P2 k) J
Chautan, M., G. Chazal, F. Cecconi, P. Gruss, and P. Golstein. 1999. Interdigital cell death can occur through a necrotic and caspase-independent pathway. Curr. Biol. 9:967–970.4 X2 k. _6 C, c; }6 x' O
0 \3 l& e2 G; i; ~; o/ O6 E" j/ ^
Clarke, P.G. 1990. Developmental cell death: morphological diversity and multiple mechanisms. Anat. Embryol. (Berl.). 181:195–213.
+ x; d- A0 \* R& n, r1 N
6 l4 W* j8 P6 W* l, G5 ^0 `- I' zClemens, M.J., M. Bushell, I.W. Jeffrey, V.M. Pain, and S.J. Morley. 2000. Translation initiation factor modifications and the regulation of protein synthesis in apoptotic cells. Cell Death Differ. 7:603–615.; @: O" Q( Z7 E. w

. q- N# [* c) y* f; aColbourne, F., G.R. Sutherland, and R.N. Auer. 1999. Electron microscopic evidence against apoptosis as the mechanism of neuronal death in global ischemia. J. Neurosci. 19:4200–4210.4 Z8 n1 Q$ A0 V2 }- w
2 _! g" [) U- u7 c
Ehrenfeld, E. 1982. Poliovirus-induced inhibition of host cell protein synthesis. Cell. 28:435–436.
( z6 i+ S6 C; g6 y0 g9 Z- M" k) y0 v1 Z. i3 _# f
Etchison, D., S.C. Milburn, I. Edery, N. Sonenberg, and J.W. Hershey. 1982. Inhibition of HeLa cell protein synthesis following poliovirus infection correlates with the proteolysis of a 220,000-dalton polypeptide associated with eucaryotic initiation factor 3 and a cap binding protein complex. J. Biol. Chem. 257:14806–14810.
3 |- g/ v5 M, k. F8 H( w8 q
6 G8 h6 j3 s/ GHengartner, M.O. 2000. The biochemistry of apoptosis. Nature. 407:770–776.# t4 d. y( w) J% |. x
; V0 v5 n8 I9 V# N9 N' u
Holler, N., R. Zaru, O. Micheau, M. Thome, A. Attinger, S. Valitutti, J.L. Bodmer, P. Schneider, B. Seed, and J. Tschopp. 2000. Fas triggers an alternative, caspase-8-independent cell death pathway using the kinase RIP as effector molecule. Nat. Immunol. 1:489–495.
1 L0 N  w/ f4 F% h7 l
) I+ e' s) Z) J: o3 [) L7 `Houge, G., B. Robaye, T.S. Eikhom, J. Golstein, G. Mellgren, B.T. Gjertsen, M. Lanotte, and S.O. Doskeland. 1995. Fine mapping of 28S rRNA sites specifically cleaved in cells undergoing apoptosis. Mol. Cell. Biol. 15:2051–2062.
3 L5 W. L  F7 T' m" x6 M# Z) Z4 b2 c" R! U
Hsu, L.C., J.M. Park, K. Zhang, J.L. Luo, S. Maeda, R.J. Kaufman, L. Eckmann, D.G. Guiney, and M. Karin. 2004. The protein kinase PKR is required for macrophage apoptosis after activation of Toll-like receptor 4. Nature. 428:341–345.
7 Q3 t; `: A' s1 E7 p; r! w9 L3 H% M
Kalai, M., G. Van Loo, T. Vanden Berghe, A. Meeus, W. Burm, X. Saelens, and P. Vandenabeele. 2002. Tipping the balance between necrosis and apoptosis in human and murine cells treated with interferon and dsRNA. Cell Death Differ. 9:981–994.4 h. ]4 w' ]5 _+ T( K1 o' d1 T8 [' \
6 |1 l; K  W& u6 B3 a
Kawahara, A., Y. Ohsawa, H. Matsumura, Y. Uchiyama, and S. Nagata. 1998. Caspase-independent cell killing by Fas-associated protein with death domain. J. Cell Biol. 143:1353–1360.
& e0 [) k2 \' d3 |: v! {1 U
/ `* L7 M5 _! t$ P/ X4 v! SLamkanfi, M., W. Declercq, M. Kalai, X. Saelens, and P. Vandenabeele. 2002. Alice in caspase land. A phylogenetic analysis of caspases from worm to man. Cell Death Differ. 9:358–361.; r! x5 g. h! q4 z. u2 K7 c- n* M# [

  w" O: G7 o) [( D1 O- ALevine, B., and D.J. Klionsky. 2004. Development by self-digestion: molecular mechanisms and biological functions of autophagy. Dev. Cell. 6:463–477.. Z) s" j1 B3 t( @! h# M# ^( b
, n: i, d; ^% C2 Y" M
Lin, Y., S. Choksi, H.M. Shen, Q.F. Yang, G.M. Hur, Y.S. Kim, J.H. Tran, S.A. Nedospasov, and Z.G. Liu. 2004. Tumor necrosis factor-induced nonapoptotic cell death requires receptor-interacting protein-mediated cellular reactive oxygen species accumulation. J. Biol. Chem. 279:10822–10828." `) E/ f5 a  I0 i$ B! w# n4 Y
2 g% ^, e) @! f7 T( f
Nicotera, P., M. Leist, and L. Manzo. 1999. Neuronal cell death: a demise with different shapes. Trends Pharmacol. Sci. 20:46–51.6 h+ ?5 G& S; N' A7 r0 e

+ z! n! y/ a( a( G; H. ^+ bPestova, T.V., V.G. Kolupaeva, I.B. Lomakin, E.V. Pilipenko, I.N. Shatsky, V.I. Agol, and C.U. Hellen. 2001. Molecular mechanisms of translation initiation in eukaryotes. Proc. Natl. Acad. Sci. USA. 98:7029–7036." }/ u2 l1 r  Y3 x/ U1 p

3 m- G$ `& W1 B; V1 h+ S& K. ?, fSaelens, X., M. Kalai, and P. Vandenabeele. 2001. Translation inhibition in apoptosis: caspase-dependent PKR activation and eIF2-alpha phosphorylation. J. Biol. Chem. 276:41620–41628.
! |+ x; L# J0 h' `) V' V4 ^& w  V+ d
Sauter, B., M.L. Albert, L. Francisco, M. Larsson, S. Somersan, and N. Bhardwaj. 2000. Consequences of cell death: exposure to necrotic tumor cells, but not primary tissue cells or apoptotic cells, induces the maturation of immunostimulatory dendritic cells. J. Exp. Med. 191:423–434.
# F' b% J0 F1 F2 L2 U5 c
& O8 [( S4 \6 [" C8 q& cSchweichel, J.U., and H.J. Merker. 1973. The morphology of various types of cell death in prenatal tissues. Teratology. 7:253–266.; O4 i  S) J+ a6 j
2 c! p: @/ P% W: \
Vanden Berghe, T., M. Kalai, G. Van Loo, W. Declercq, and P. Vandenabeele. 2003. Disruption of HSP90 function reverts tumor necrosis factor-induced necrosis to apoptosis. J. Biol. Chem. 278:5622–5629.
2 A+ P/ ^0 r, U, i( g
' c5 s) e; ]+ c2 b* w' NVanden Berghe, T., G. van Loo, X. Saelens, M. van Gurp, G. Brouckaert, M. Kalai, W. Declercq, and P. Vandenabeele. 2004. Differential signaling to apoptotic and necrotic cell death by Fas-associated death domain protein FADD. J. Biol. Chem. 279:7925–7933.' f# c. [* J4 s6 p' ~. u: ]2 b
- Z9 c5 h# x( m
Vercammen, D., G. Brouckaert, G. Denecker, M. Van de Craen, W. Declercq, W. Fiers, and P. Vandenabeele. 1998. Dual signaling of the Fas receptor: initiation of both apoptotic and necrotic cell death pathways. J. Exp. Med. 188:919–930.(Xavier Saelens, Nele Fest)
作者: 张佳    时间: 2015-6-3 16:52

给我一个女人,我可以创造一个民族;给我一瓶酒,我可以带领他们征服全世界 。。。。。。。。。  
作者: yukun    时间: 2015-6-19 17:43

间充质干细胞
作者: MIYAGI    时间: 2015-6-25 21:39

回帖是种美德.  
作者: sky蓝    时间: 2015-7-12 19:23

哎 怎么说那~~  
作者: 剑啸寒    时间: 2015-7-23 10:26

世界上那些最容易的事情中,拖延时间最不费力。  
作者: 榴榴莲    时间: 2015-8-1 14:26

不错不错,我喜欢看  
作者: 泡泡鱼    时间: 2015-8-2 12:18

要不我崇拜你?行吗?  
作者: sky蓝    时间: 2015-9-3 13:04

不错不错.,..我喜欢  
作者: 兔兔    时间: 2015-10-13 08:54

呵呵 那就好好玩吧~~~~  
作者: 橙味绿茶    时间: 2015-11-1 16:10

长时间没来看了 ~~  
作者: 科研人    时间: 2015-12-9 08:27

不看白不看,看也不白看  
作者: 龙水生    时间: 2015-12-11 11:41

角膜缘上皮干细胞
作者: 罗马星空    时间: 2015-12-24 15:54

我的啦嘿嘿  
作者: popobird    时间: 2016-2-19 16:10

@,@..是什么意思呀?  
作者: 刘先生    时间: 2016-2-24 12:01

非常感谢楼主,楼主万岁万岁万万岁!  
作者: 3344555    时间: 2016-3-16 15:01

其实回帖算是一种没德德,所以我快成圣人了  
作者: 小丑的哭泣    时间: 2016-3-21 15:27

加油啊!!!!顶哦!!!!!  
作者: Whole    时间: 2016-3-28 16:01

在线等在线等  
作者: 知足常乐    时间: 2016-4-3 16:01

长时间没来看了 ~~  
作者: 大小年    时间: 2016-4-13 16:18

嘿嘿......哈哈......呵呵.....哟~呼  
作者: dreamenjoyer    时间: 2016-4-23 09:54

我卷了~~~~~~~  
作者: 加菲猫    时间: 2016-5-7 20:54

这样的贴子,不顶说不过去啊  
作者: HongHong    时间: 2016-6-1 09:54

我卷了~~~~~~~  
作者: 3344555    时间: 2016-6-21 19:34

呵呵,等着就等着....  
作者: 小小C    时间: 2016-6-21 21:01

爷爷都是从孙子走过来的。  
作者: 旅美学者    时间: 2016-7-22 20:55

脂肪干细胞
作者: biopxl    时间: 2016-8-15 21:18

强人,佩服死了。呵呵,不错啊  
作者: ikiss    时间: 2016-8-28 21:41

水至清则无鱼,人至贱则无敌!  
作者: 狂奔的蜗牛    时间: 2016-9-22 16:18

谢谢哦  
作者: Diary    时间: 2016-10-14 14:44

表观遗传学
作者: 杏花    时间: 2016-11-3 09:35

好人一生平安  
作者: foxok    时间: 2016-11-4 12:43

厉害!强~~~~没的说了!  
作者: 安生    时间: 2016-12-4 08:00

一个子 没看懂  
作者: dongmei    时间: 2016-12-26 19:01

似曾相识的感觉  
作者: aliyun    时间: 2017-1-9 17:35

不错!  
作者: aliyun    时间: 2017-1-15 08:54

厉害!强~~~~没的说了!  
作者: 咕咚123    时间: 2017-1-19 19:35

昨晚多几分钟的准备,今天少几小时的麻烦。  
作者: cjms    时间: 2017-1-23 13:00

每天到干细胞之家看看成了必做的事情
作者: lab2010    时间: 2017-2-16 12:54

这个贴好像之前没见过  
作者: 小丑的哭泣    时间: 2017-2-25 22:27

好帖子,要顶!
作者: 泡泡鱼    时间: 2017-2-26 23:04

我毫不犹豫地把楼主的这个帖子收藏了  
作者: 干细胞2014    时间: 2017-3-2 10:35

(*^__^*) 嘻嘻……  
作者: 多来咪    时间: 2017-3-6 19:01

既然来了,就留个脚印  
作者: 再来一天    时间: 2017-3-6 21:34

鉴定完毕.!  
作者: 干细胞2014    时间: 2017-4-17 15:18

谁能送我几分啊  
作者: feixue66    时间: 2017-4-18 00:20

顶下再看  
作者: 墨玉    时间: 2017-4-19 17:15

今天临床的资料更新很多呀
作者: 糊涂小蜗牛    时间: 2017-4-20 03:46

一个子 没看懂  
作者: 小敏    时间: 2017-4-22 08:02

嘿嘿......哈哈......呵呵.....哟~呼  
作者: ikiss    时间: 2017-4-29 10:27

嘿...反了反了,,,,  
作者: 未必温暖    时间: 2017-5-11 15:18

挺好啊  
作者: Whole    时间: 2017-5-16 10:54

心脏干细胞
作者: tempo    时间: 2017-5-26 19:43

严重支持!
作者: 心仪    时间: 2017-6-7 20:41

给我一个女人,我可以创造一个民族;给我一瓶酒,我可以带领他们征服全世界 。。。。。。。。。  
作者: HongHong    时间: 2017-6-8 09:10

21世纪,什么最重要——我!  
作者: HongHong    时间: 2017-7-24 18:51

鉴定完毕.!  
作者: 心仪    时间: 2017-9-8 06:49

…没我说话的余地…飘走  
作者: bioprotein    时间: 2017-9-8 17:01

免疫细胞疗法治疗肿瘤有效  
作者: xuguofeng    时间: 2017-9-9 01:58

我起来了 哈哈 刚才迷了会  
作者: MIYAGI    时间: 2017-9-20 02:18

角膜缘上皮干细胞
作者: popobird    时间: 2017-9-27 02:54

生殖干细胞
作者: 温暖暖    时间: 2017-10-3 02:49

好贴坏贴,一眼就看出去  
作者: 123456zsz    时间: 2017-10-8 19:42

顶你一下.  
作者: s06806    时间: 2017-10-14 13:35

都是那么过来的  
作者: xiao2014    时间: 2017-10-16 13:35

来上茶~~~~  
作者: 分子工程师    时间: 2017-10-24 17:53

做对的事情比把事情做对重要。  
作者: ines    时间: 2017-10-26 15:10

很好!很强大!  
作者: Kuo    时间: 2017-11-22 18:10

孜孜不倦, 吾等楷模 …………  
作者: lab2010    时间: 2017-11-24 08:18

免疫细胞疗法治疗肿瘤有效  
作者: 大小年    时间: 2017-12-16 19:01

嘿嘿  
作者: biodj    时间: 2017-12-29 22:54

一楼的位置好啊..  
作者: 知足常乐    时间: 2018-1-4 13:01

应该加分  
作者: xuguofeng    时间: 2018-1-12 04:48

希望大家帮我把这个帖发给你身边的人,谢谢!  
作者: 咕咚123    时间: 2018-1-25 13:43

dddddddddddddd  
作者: yunshu    时间: 2018-1-27 11:35

正好你开咯这样的帖  
作者: xm19    时间: 2018-2-5 21:09

我又回复了  
作者: dogcat    时间: 2018-2-9 16:32

支持一下吧  
作者: highlight    时间: 2018-2-18 07:01

加油啊!!!!顶哦!!!!!支持楼主,支持你~  
作者: 咕咚123    时间: 2018-3-14 12:42

我在努力中  
作者: lab2010    时间: 2018-4-6 01:35

琴棋书画不会,洗衣做饭嫌累。  
作者: xiao2014    时间: 2018-4-12 17:09

呵呵,等着就等着....  
作者: marysyq    时间: 2018-4-16 09:01

21世纪,什么最重要——我!  
作者: dada    时间: 2018-4-16 18:00

声明一下:本人看贴和回贴的规则,好贴必看,精华贴必回。  
作者: lalala    时间: 2018-4-20 13:10

老大,我好崇拜你哟  
作者: 咕咚123    时间: 2018-5-4 02:36

来几句吧  
作者: 123456zsz    时间: 2018-6-1 06:02

哈哈,有意思~顶顶 ,继续顶顶。继续顶哦  
作者: 坛中酒    时间: 2018-6-1 23:36

今天的干细胞研究资料更新很多呀
作者: 365wy    时间: 2018-6-3 14:43

好贴坏贴,一眼就看出去  
作者: 糊涂小蜗牛    时间: 2018-6-15 20:54

端粒酶研究
作者: 舒思    时间: 2018-6-18 21:39

一个人最大的破产是绝望,最大的资产是希望。  
作者: 生科院    时间: 2018-6-30 01:53

回个帖子支持一下!
作者: 追风    时间: 2018-7-25 19:12

不错的东西  持续关注  
作者: 橙味绿茶    时间: 2018-8-16 14:35

顶的就是你  
作者: 大小年    时间: 2018-8-21 01:44

不错,支持下  
作者: changfeng    时间: 2018-9-6 02:05

不错啊! 一个字牛啊!  
作者: 水木清华    时间: 2018-9-20 06:04

(*^__^*) 嘻嘻……   
作者: beautylive    时间: 2018-9-24 11:43

好困啊  
作者: foxok    时间: 2018-9-27 02:36

牛牛牛牛  
作者: foxok    时间: 2018-9-27 21:51

嘿...反了反了,,,,  




欢迎光临 干细胞之家 - 中国干细胞行业门户第一站 (http://www.stemcell8.cn/) Powered by Discuz! X1.5