|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
Prepublished online as a Blood First Edition Paper on September 26, 2002; DOI 10.1182/blood-2002-06-1688.
IMMUNOBIOLOGY
From the Department of Nephrology and Department of
Immunohematology and Blood Transfusion, Leiden University Medical
Center, Leiden, The Netherlands; Department of Pulmonary
Diseases, University Medical Center Utrecht, Utrecht, The
Netherlands.
The longevity of dendritic cells (DCs) is a critical regulatory
factor influencing the outcome of immune responses. Recently, we
demonstrated that the immunosuppressive drug rapamycin (Rapa) specifically induces apoptosis in DCs but not in other myeloid cell
types. The present study unraveled the mechanism used by Rapa to induce
apoptosis in human monocyte-derived DCs. Our data demonstrate that
granulocyte-macrophage colony-stimulating factor (GM-CSF)
preserves DC survival specifically via the phosphatidylinositol-3 lipid
kinase/mammalian target of rapamycin (PI3K/mTOR) signaling pathway,
which is abrogated by Rapa at the level of mTOR. Disruption of this
GM-CSF signaling pathway induced loss of mitochondrial membrane
potential, phosphatidyl-serine exposure, and nuclear changes. Apoptosis
of these nonproliferating DCs was preceded by an up-regulation of the
cell cycle inhibitor p27KIP1. Overexpression of
p27KIP1 in DCs using adenoviral gene transduction revealed
that apoptosis is directly regulated by p27KIP1.
Furthermore, both overexpression of p27KIP1 and disruption
of the GM-CSF/PI3K/mTOR signaling pathway decreased the expression of
the antiapoptotic protein mcl-1. This mTOR/p27KIP1/mcl-1
survival seems unique for DCs and may provide novel opportunities to
influence immune responses by specific interference with the life span
of these cells.
(Blood. 2003;101:1439-1445) Apoptosis, or programmed cell death, is a
physiologic process that is required for the normal development and
maintenance of tissue homeostasis.1 It is an active
process that is regulated by gene products, which either block or
accelerate programmed cell death. In most cells, the apoptotic program
is always ready to be executed unless continuously inhibited by
extracellular survival factors.2 Apoptosis regulates many
aspects of immunologic homeostasis, including initiation, magnitude,
and termination of immune responses. Dendritic cells (DCs) play a
critical role in the diverse facets of immune regulation, ranging from
tolerance induction and the prevention of autoimmunity to the induction of antitumor immunity and the protection against infectious
agents.3,4
DCs are the most potent antigen-presenting cells. They play a major
role in the uptake, transport, and presentation of antigens and have
the unique capacity to stimulate naive T lymphocytes.5 In
addition to their polarizing capacity on contact with naive T
cells,4 they can interact with B cells6 and
natural killer (NK) cells7 and thus direct the character
of the immune response. Although of possible biologic importance to
down-regulate immune responses, apoptosis in DCs has been scarcely
investigated. Several different death receptors have been identified on
DCs, including Fas (CD95), tumor necrosis factor (TNF)
receptor, and TNF receptor-related apoptosis-inducing ligand receptor
(TRAIL-R), suggesting a role for death ligand-induced DC
apoptosis.8-10 DC apoptosis can also be triggered by UVB
radiation,11 glucocorticoids, reactive haptens, infectious
pathogens, tumor cells, and NK cells.12 Although recently,
specific nuclear factor Previously, we demonstrated that rapamycin (Rapa) specifically induces
apoptosis in both monocyte-derived DCs and DCs generated from
CD34+ precursors but not in monocytes or
macrophages.15 Rapa, which is an immunosuppressive drug
introduced to prevent allograft rejection,16 is
extensively studied for its effect on T lymphocytes and is known mainly
for its antiproliferative effect.17 The drug is structurally related to FK506 that also inhibits T-cell proliferation. Although FK506 and Rapa bind to the same intracellular protein, FKBP-12, the resulting complexes interfere with distinct signaling pathways.18,19 FK506 inhibits production of interleukin 2 (IL-2), via inhibition of calcineurin, whereas Rapa inhibits growth
factor signaling rather than growth factor synthesis.
The Rapa/FKBP12 complex acts to inhibit the activity of mammalian
target of rapamycin (mTOR).17,20 mTOR is a member of the
lipid kinase family with homology to phosphatidylinositol-3 lipid
kinase (PI3K). In T cells, Rapa abrogates the IL-2-induced activity of
mTOR, thereby blocking G1-S transition and proliferation. A
potential mechanism by which PI3K and mTOR exert their proliferative effects is by down-regulation of the cyclin-dependent kinase (CDK) inhibitor p27KIP1.21 However, up-regulation of
p27KIP1 is not only linked to cell cycle arrest in
G0/1,22 but it seems also associated with
apoptosis induced by growth factor withdrawal or PI3K
inhibition.23,24
In the present study we examined the mechanism used by Rapa to induce
apoptosis in primary human DCs. Our data demonstrate that the survival
of monocyte-derived DCs, which are nonproliferating cells, requires
granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling via
the PI3K/mTOR signaling pathway. Inhibition of mTOR via Rapa leads to
increased expression of the cell cycle inhibitor p27KIP1 in
nonproliferating DCs. Overexpression of p27KIP1 by using
adenoviral gene transduction was shown to be directly responsible for
the down-regulation of the antiapoptotic bcl-2 family protein mcl-1 and
the induction of apoptosis.
Reagents
Cell culture
Induction and detection of apoptosis Apoptosis induction experiments were performed in 12- or 24-well culture plates (Costar, Cambridge, MA) containing 5 × 105 DC/mL.Determination of nuclear condensation and fragmentation. Cells were harvested at the indicated time points and fixed with 1% paraformaldehyde on ice. Cytospin preparations were made and stained with Hoechst 33258 (Molecular Probes, Leiden, The Netherlands) for 3 minutes at room temperature. The percentage of apoptotic cells was determined by examining 200 cells and counting the cells that were characterized by condensed or fragmented nuclei. Determination of phosphatidyl-serine exposure. Cells were harvested at the indicated time points, washed, labeled with annexin V-fluorescein isothiocyanate (FITC; Apoptest FITC kit; Nexins Research BV, Kattendijke, The Netherlands) for 30 minutes on ice, and subsequently taken up in 1 µg/mL propidium iodide (PI; Molecular Probes). Annexin V/PI staining was conducted on a FACScan and analyzed using WinMDI software (Becton Dickinson). Determination of DNA fragmentation (sub-G0 analysis).
Cells were harvested, washed in 1 mM EDTA/PBS
(ethylenediaminetetraacetic acid/phosphate-buffered saline), and fixed
in 90% ethanol for at least 30 minutes at Determination of mitochondrial transmembrane potential. Mitochondrial dysfunction was assessed by using rhodamine 123 (Rh123; Molecular Probes). Cells were incubated at 37°C for 30 minutes in the presence of 0.1 µg/mL Rh123. Then cells were washed and resuspended in PBS, either with or without 1 µg/mL PI, and Rh123 retention was conducted on a FACScan. Preparation of whole cell lysates and Western blot analysis Cultured DCs were harvested, washed, and lysed in Triton X-100 buffer, containing 20 mM Tris (tris(hydroxymethyl)aminomethane)-HCl (pH 7.4), 137 mM NaCl, 10% glycerol, 1% Triton X-100, 2 mM EDTA, 1 mM phenylmethyl sulfonyl fluoride (PMSF), 2 µg/mL leupeptin, 2 µg/mL antipain, 2 µg/mL chymostatin, and 5 U/mL trasylol. The protein concentration was determined by using the bicinchonic acid (BCA) protein assay (Pierce Chemical, Rockford, IL). Each protein sample was separated under reducing conditions on a 12% polyacrylamide sodium dodecyl sulfate (SDS) gel and semi-dry electroblotted on polyvinylidene fluoride (PVDF) membranes (Immobilon-p; Millipore, Bedford, MA). Membranes were incubated with 2% casein in PBS-0.05% Tween 20 for blocking, and then the primary antibody, either mouse-antihuman p27KIP1 (F-8; Santa Cruz Biotechnology, Santa Cruz, CA) or rabbit-antihuman mcl-1 (S-19; Santa Cruz Biotechnology), was added. After incubation with the appropriate secondary antibody (horseradish peroxidase [HRP]-conjugated swine-antirabbit immunoglobulin or goat-antimouse immunoglobulin both from Dako, Glostrup, Denmark) detection was performed with Supersignal (Pierce), and the blots were exposed to Hyperfilm films (Amersham Pharmacia Biotech, United Kingdom). Membranes were stripped by using Restore Stripping Buffer (Pierce) to investigate the expression of several specific proteins within one experiment. Equal protein loading was verified by Coomassie blue staining of the blot, which allows comparison over the whole molecular weight range.Recombinant adenoviral vectors Replication-deficient adenoviral vectors containing either human p27KIP1 cDNA (rAd-p27) or the LacZ gene (rAd-LacZ)24 were obtained from Drs I. Naruse and H. Hoshino (Gunma University School of Medicine, Maebashi, Japan). Adenoviral stocks were generated and purified by double CsCl density gradient centrifugation as described previously.26 To remove the CsCl, the virus bands were dialyzed against a Tris buffer (25 mM Tris-Cl, 137 mM NaCl, 5 mM KCl, 0.73 mM Na2HPO4, 0.9 mM CaCl, 0.5 mM MgCl2, pH 7.45). The final dialysis was performed with this Tris buffer containing 5% sucrose, and then virus stocks were stored at 80°C
until further use.
Infection of DCs with rAd Day 6 immature DCs (0.4 × 106) were resuspended in 100 µL PBS and incubated with rAd-LacZ (2.0 × 1010 pfu/mL) or rAd-p27 (1.2 × 1010 pfu/mL) (multiplicity of infection [MOI], 1000).27 After 2 hours at 37°C, DCs were washed twice with PBS to remove free adenoviruses. Then cells were resuspended in RPMI 1640 containing 10% FCS and P/S
supplemented with 5 ng/mL GM-CSF and 10 ng/mL IL-4 and cultured at
37°C in a 5% CO2 incubator.
After 24 hours of culture, DCs were fixed with 0.2% glutaraldehyde/2% formaldehyde in PBS for 5 minutes at 4°C. Fixed cells were incubated in a stain solution containing 5 mM potassium ferrocyanide2+, 5 mM potassium ferrocyanide3+, 2 mM MgCl2, and 1 mg/mL X-gal (Sigma) for 4 hours at 37°C. The percentage of LacZ+ cells (blue cells) was calculated by light microscopy.
Monocytes and DCs differ in their survival mechanisms As demonstrated previously, addition of GM-CSF to monocyte cultures increased the yield of functional immature DCs on culture with IL-4.28 To examine whether GM-CSF increases cell recovery by affecting cell survival at the start of culture, ie, an effect on freshly isolated monocytes, or by promoting DC survival, both monocytes and DCs were cultured with or without GM-CSF for 48 hours. GM-CSF withdrawal, but not IL-4 withdrawal, from DC cultures strongly induced apoptosis (Figure 1). GM-CSF withdrawal induced the typical characteristics of apoptosis, including nuclear condensation and fragmentation visualized by Hoechst staining (Figure 1A) and DNA fragmentation as demonstrated by an increased sub-G0 fraction after DNA staining with propidium iodide (Figure 1B). The loss of mitochondrial transmembrane potential ( m) on GM-CSF deprivation, as determined by Rh123
retention, suggested an active role of mitochondria in the induction of
apoptosis (Figure 1C).
Both mitogen-activated protein kinase (MAPK) and PI3K/mTOR signaling
pathways have been suggested to play a role in GM-CSF-induced survival
of various hematopoietic cells. To investigate the involvement of the
distinct signaling pathways in GM-CSF-mediated survival of DCs, the
activation of the MAPK family members extracellular signal-related
kinase (ERK) and p38, PI3K, and mTOR was blocked by culturing
DCs in the presence of PD98059, SB203580, LY294002, and Rapa,
respectively. PD98059 slightly induced apoptosis, whereas inhibition of
p38 by SB203580 did not (Figure 2A). Both
inhibition of PI3K using LY294002 and inhibition of mTOR using Rapa
induced apoptosis comparable to GM-CSF deprivation, demonstrating a
critical role for PI3K/mTOR signaling in the regulation of DC survival. Inhibition of PI3K, ERK, or p38 in monocytes slightly induced apoptosis
(Figure 2A). As shown previously,15 monocytes were completely insensitive for the proapoptotic activity of Rapa, demonstrating that the longevity of DCs and their precursors, ie, the
monocytes, are regulated by different survival mechanisms.
DC survival requires GM-CSF signaling via PI3K and mTOR Like treatment of DCs with Rapa to inhibit mTOR,15 blockade of PI3K in DCs by addition of LY294002 time- and dose-dependently induced apoptosis that was characterized by nuclear condensation and fragmentation (Figure 2B) and DNA fragmentation (data not shown). In addition to the data obtained from GM-CSF deprivation experiments, both LY294002 and Rapa demonstrated loss ofm associated with the percentage of apoptosis induced
(Figure 2C). In line with the induction of apoptosis, inhibition of ERK
by PD98059 only slightly induced loss of m, and
inhibition of p38 did not significantly change m
(Figure 2C).
Rapa increases the expression of p27KIP1 Because mTOR is the most downstream target in GM-CSF-driven survival of DCs as determined so far, and because Rapa is clinically used as an immunosuppressive drug, we further explored the mechanism used by Rapa to specifically induce apoptosis in DCs. In T lymphocytes, Rapa exerts its effects via the up-regulation of the cell cycle inhibitor p27KIP1. An increased expression of p27KIP1 in nonproliferating eosinophils has been shown to correlate with the induction of apoptosis.23 Therefore, we investigated whether Rapa or GM-CSF signaling could influence p27KIP1 protein expression in monocyte-derived DCs, which are also nonproliferating cells. A 48-hour incubation in the presence of Rapa strongly increased the expression of p27KIP1 (Figure 3A). When DCs were simultaneously treated with FK506, which antagonizes the apoptotic effect of Rapa (Figure 3B), the Rapa-induced p27KIP1 expression also could be inhibited (Figure 3A). Although Rapa required more than 24 hours to induce strong apoptosis,15 the effect on the expression of p27KIP1 was observed relatively early. Treatment with Rapa for 5 hours already increased the expression of p27KIP1 that was not further increased by an extended incubation period in the presence of the drug (Figure 3C-D).
p27KIP1 expression is increased after GM-CSF withdrawal or PI3K inhibition To support the hypotheses that Rapa-induced apoptosis is mediated by an increased p27KIP1 expression, we analyzed the effect of cytokine withdrawal and PI3K inhibition on the expression of p27KIP1. All culture conditions that lead to apoptosis of DCs, including cultures without GM-CSF or with the PI3K inhibitor LY294002, were accompanied by an increased p27KIP1 expression, whereas no changes were observed in conditions without apoptosis, such as IL-4 withdrawal or DMSO (Figure 4A).
Monocytes were completely resistant to Rapa-induced apoptosis (Figure 2A). Rapa did not increase p27KIP1 in cultured peripheral blood monocytes (Figure 4B), confirming the hypothesis that Rapa-induced apoptosis is preceded and accompanied by an increased expression of p27KIP1. p27KIP1 gene transduction induces apoptosis in DCs To determine whether up-regulation of p27KIP1 has a causative role in Rapa-induced apoptosis of monocyte-derived DCs, DCs were infected with recombinant adenoviruses (rAd) containing human p27KIP1 cDNA. Infection of DCs with rAd-LacZ served as a control and showed that transduction efficiencies of above 90% were achieved at an MOI of 1000 (Figure 5A). Expression of p27KIP1 protein after infection with the adenoviral vectors was measured by Western blot analysis. A strong overexpression of p27KIP1 was detected at 48 hours after rAd-p27 infection (Figure 5B), which was not further increased after 72 hours. Expression of p27KIP1 protein in DCs infected with rAd-LacZ was not different from control levels.
Cells were harvested after 48 hours of incubation. Whole cell lysates were prepared, equal amounts of protein (20 µg/lane) were loaded, and the levels of p27KIP1 were determined. Data shown are representative for 3 independent experiments with different donors. In the presence of GM-CSF, DCs infected with rAd-p27 went into
apoptosis as demonstrated by an increased annexin V binding within the
PI Increased expression of p27KIP1 is responsible for down-regulation of mcl-1 As demonstrated earlier, apoptosis of DCs induced as a consequence of a disruptive GM-CSF/PI3K/mTOR signaling pathway is associated with loss of mitochondrial integrity. The bcl-2 family of proteins, containing both antiapoptotic and proapoptotic members, controls mitochondrial permeability and thus plays a critical role in the regulation of apoptosis. mcl-1 is an antiapoptotic protein, which is thought to be an important bcl-2 family member in GM-CSF-mediated survival of hematopoietic cells.29Western blot analysis of lysates prepared after rAd-p27 infection
demonstrated that increased expression of p27KIP1 directly
causes down-regulation of mcl-1 protein expression in DCs (Figure
6A). The correlation between the
down-regulation of mcl-1 and the interference in the GM-CSF signaling
pathway at the level of PI3K and mTOR finally leading to apoptosis was
further examined. Addition of either LY294002 or Rapa to DC cultures, as well as deprivation of GM-CSF, induced a down-regulation of mcl-1
that correlated with the percentage of apoptosis induced, thereby
demonstrating that expression of mcl-1 is tightly regulated via PI3K
and mTOR in response to GM-CSF (Figure 6B).
A more detailed analysis of the effect of Rapa on the expression of mcl-1 in DCs was performed. The Rapa-induced reduction of mcl-1 protein levels was already observed within 24 hours of incubation, as demonstrated by Western blot analysis, but became more pronounced after 48 hours of treatment, finally resulting in a 2-fold reduction in mcl-1 protein levels (Figure 6C).
In the present study we show that defective GM-CSF signaling in human nonproliferating DCs, either because of selective inhibition of PI3K or mTOR, or GM-CSF deprivation, caused an increased expression of the cyclin-dependent kinase (CDK) inhibitor p27KIP1 prior to a decreased expression of the antiapoptotic protein mcl-1 and apoptosis. Overexpression of p27KIP1 in DCs by using adenoviral gene transduction revealed that both mcl-1 expression and cell survival are directly regulated by p27KIP1. By examining the mechanism used by Rapa for the induction of apoptosis in DCs, we found that the PI3K/mTOR pathway is a critical signaling route for GM-CSF-driven survival of monocyte-derived DCs. GM-CSF is a potent growth factor for a variety of hematopoietic cells. On binding to its heterodimeric receptor, GM-CSF activates several signaling pathways, including the Jak-Stat (Janus kinase and signal transducer and activator of transcription) and Ras pathways,30,31 resulting in both mitogenic and antiapoptotic signals. Although downstream from Ras, both Raf/MAPK and PI3K/mTOR pathways have been suggested to play a role in cytokine-driven survival of hematopoietic cells,31,32 we found that for monocyte-derived DCs only the PI3K/mTOR pathway is absolutely necessary. In line with a previous study on lipopolysaccharide (LPS)-stimulated monocyte-derived DCs,33 which also demonstrate a cell death-inducing effect of LY294002 but not of PD98059 or SB203580, we observed only a limited role for ERK activation in DC survival. Although our data suggest that Rapa specifically counteracts the antiapoptotic activity of GM-CSF that results in an increased expression of p27KIP1, the fact that Rapa further increases apoptosis on GM-CSF withdrawal (data not shown) might suggest additional modes of action of Rapa. p27KIP1 is an inhibitor of cell cycle progression, exerting its effect through interaction with cyclin-CDK complexes and arresting cells in G0/1.22 p27KIP1 is present at relatively high levels in quiescent cells and is down-regulated by mitogenic stimulation21,34,35; the latter process being blocked by Rapa.21 It is important to note that a cell cycle inhibitor can also play a decisive role in a nonproliferating cell type such as DCs or, as shown, nonproliferating eosinophils.23 However, although both in eosinophils and in the murine IL-3-dependent cell line Ba/F3 apoptosis was linked to increased p27KIP1 and interference with the PI3K pathway, apoptosis could not be induced by Rapa.23 This finding further underlines the specificity of Rapa toward DC apoptosis. It has been shown that p27KIP1-deficient mice demonstrate an increased survival of bone marrow-derived stem cells when cultured ex vivo compared with wild-type mice,23 but the immune status has not been specifically investigated.36 The mechanism by which p27KIP1 can regulate cell survival is not known. In search of a potential mechanism by which p27KIP1 could modulate GM-CSF-driven DC survival, we focused on the regulation of mcl-1. mcl-1, initially cloned as a gene differentially expressed in human ML-1 myeloid leukemia cells,37 shows extensive homology to bcl-2. Like bcl-2 and bcl-xL, mcl-1 heterodimerizes with bax38 and thus plays an important role in the prevention of apoptosis. Although mcl-1 and bcl-2 show strong homology, their distribution, expression levels, and regulation of apoptosis are independently regulated.39-41 mcl-1 is thought to be an important protein in IL-3 and GM-CSF-mediated survival of hematopoietic cells,29,42 a finding supported by the fact that mcl-1 transgenic mice possess an enhanced viability in a wide range of hematopoietic cell types.43 We demonstrate that the protein level of mcl-1 in DCs is tightly regulated by GM-CSF signaling via PI3K and mTOR. Despite the large decrease in the level of mcl-1 protein following treatment with Rapa or LY294002, no significant decrease in the level of mcl-1 mRNA was observed (data not shown). This finding is consistent with previous work demonstrating that GM-CSF-mediated mcl-1 expression is regulated at the translational level by a PI3K-controlled pathway.44 LY294002-treated human monocyte-derived macrophages45 showed also a marked decrease of mcl-1 protein expression, but they appear to have different PI3K/mcl-1 survival mechanisms than monocyte-derived DCs, because monocytes and macrophages do not undergo Rapa-induced apoptosis (Figure 2).15 In addition, we showed that monocytes do not increase their p27KIP1 expression on Rapa treatment, whereas DCs clearly do. Therefore, alternative survival mechanisms might be present in monocytes/macrophages that regulate the expression of mcl-1 independently of mTOR and p27KIP1. In conclusion, given their central role in the immune system, DCs are important targets for both immunosuppressive or immunostimulatory therapies.46-50 Understanding the survival program of DCs will provide the opportunity to either increase immune responses by prolonged DC survival or to terminate these responses by specific depletion of the cells. Rapa, which has been introduced recently as an effective drug to prevent allograft rejection, might partially exert its immunosuppressive effect by virtue of its proapoptotic effect on DCs. Our finding that the survival of monocyte-derived DCs is specifically regulated by the GM-CSF signaling pathway via PI3K/mTOR and involves the regulation of p27KIP1 and mcl-1 might provide additional tools to control immune responses.
We thank Drs I. Naruse and H. Hoshino (Gunma University School of Medicine, Maebashi, Japan) for providing the adenoviral vectors containing either p27KIP1 or LacZ, and M. J. W. E. Rabelink (Department of Molecular Cell Biology), Dr L. T. C. Peltenburg (Department of Clinical Oncology), and N. Schlagwein (Department of Nephrology; all from LUMC, Leiden, The Netherlands) for technical assistance. C. van K. is a fellow of the Royal Netherlands Academy of Arts and Sciences (KNAW).
Submitted June 7, 2002; accepted September 17, 2002.
Prepublished online as Blood First Edition Paper, September 26, 2002; DOI 10.1182/blood-2002-06-1688.
The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734.
Reprints: Andrea M. Woltman, Leiden University Medical Center, Department of Nephrology, C3-P, Albinusdreef 2, 2333 ZA Leiden, The Netherlands; e-mail: a.m.woltman{at}lumc.nl.
1. Vaux DL, Korsmeyer SJ. Cell death in development. Cell. 1999;96:245-254[CrossRef][Medline] [Order article via Infotrieve]. 2. Raff MC. Social controls on cell survival and cell death. Nature. 1992;356:397-400[CrossRef][Medline] [Order article via Infotrieve]. 3. Banchereau J, Steinman RM. Dendritic cells and the control of immunity. Nature. 1998;392:245-252[CrossRef][Medline] [Order article via Infotrieve]. 4. Liu YJ, Kanzler H, Soumelis V, Gilliet M. Dendritic cell lineage, plasticity and cross-regulation. Nat Immunol. 2001;2:585-589[CrossRef][Medline] [Order article via Infotrieve]. 5. Banchereau J, Briere F, Caux C, et al. Immunobiology of dendritic cells. Annu Rev Immunol. 2000;18:767-811[CrossRef][Medline] [Order article via Infotrieve]. 6. Dubois B, Bridon JM, Fayette J, et al. Dendritic cells directly modulate B cell growth and differentiation. J Leukoc Biol. 1999;66:224-230[Medline] [Order article via Infotrieve].
7.
Gerosa F, Baldani-Guerra B, Nisii C, Marchesini V, Carra G, Trinchieri G.
Reciprocal activating interaction between natural killer cells and dendritic cells.
J Exp Med.
2002;195:327-333
8.
Matsue H, Edelbaum D, Hartmann AC, et al.
Dendritic cells undergo rapid apoptosis in vitro during antigen-specific interaction with CD4+ T cells.
J Immunol.
1999;162:5287-5298 9. Koppi TA, Tough-Bement T, Lewinsohn DM, Lynch DH, Alderson MR. CD40 ligand inhibits Fas/CD95-mediated apoptosis of human blood-derived dendritic cells. Eur J Immunol. 1997;27:3161-3165[Medline] [Order article via Infotrieve].
10.
Bjorck P, Banchereau J, Flores-Romo L.
CD40 ligation counteracts Fas-induced apoptosis of human dendritic cells.
Int Immunol.
1997;9:365-372
11.
Nicolo C, Tomassini B, Rippo MR, Testi R.
UVB-induced apoptosis of human dendritic cells: contribution by caspase-dependent and caspase-independent pathways.
Blood.
2001;97:1803-1808 12. Matsue H, Takashima A. Apoptosis in dendritic cell biology. J Dermatol Sci. 1999;20:159-171[CrossRef][Medline] [Order article via Infotrieve]. 13. Ouaaz F, Arron J, Zheng Y, Choi Y, Beg AA. Dendritic cell development and survival require distinct NF-kappaB subunits. Immunity. 2002;16:257-270[CrossRef][Medline] [Order article via Infotrieve].
14.
Medema JP, Schuurhuis DH, Rea D, et al.
Expression of the serpin serine protease inhibitor 6 protects dendritic cells from cytotoxic T lymphocyte-induced apoptosis: differential modulation by T helper type 1 and type 2 cells.
J Exp Med.
2001;194:657-667
15.
Woltman AM, De Fijter JW, Kamerling SW, et al.
Rapamycin induces apoptosis in monocyte- and CD34-derived dendritic cells, but not in monocytes and macrophages.
Blood.
2001;98:174-180 16. Kahan BD. Efficacy of sirolimus compared with azathioprine for reduction of acute renal allograft rejection: a randomised multicentre study. N Engl J Med. 2000;356:194-202. 17. Abraham RT, Wiederrecht GJ. Immunopharmacology of rapamycin. Annu Rev Immunol. 1996;14:483-510[CrossRef][Medline] [Order article via Infotrieve].
18.
Bierer BE, Mattila PS, Standaert RF, et al.
Two distinct signal transmission pathways in T lymphocytes are inhibited by complexes formed between an immunophilin and either FK506 or rapamycin.
Proc Natl Acad Sci U S A.
1990;87:9231-9235 19. Dumont FJ, Melino MR, Staruch MJ, Koprak SL, Fischer PA, Sigal NH. The immunosuppressive macrolides FK-506 and rapamycin act as reciprocal antagonists in murine T cells. J Immunol. 1990;144:1418-1424[Abstract].
20.
Sabers CJ, Martin MM, Brunn GJ, et al.
Isolation of a protein target of the FKBP12-rapamycin complex in mammalian cells.
J Biol Chem.
1995;270:815-822 21. Nourse J, Firpo E, Flanagan WM, et al. Interleukin-2-mediated elimination of the p27Kip1 cyclin-dependent kinase inhibitor prevented by rapamycin. Nature. 1994;372:570-573[CrossRef][Medline] [Order article via Infotrieve]. 22. Toyoshima H, Hunter T. p27, a novel inhibitor of G1 cyclin-Cdk protein kinase activity, is related to p21. Cell. 1994;78:67-74[CrossRef][Medline] [Order article via Infotrieve].
23.
Dijkers PF, Medema RH, Pals C, et al.
Forkhead transcription factor FKHR-L1 modulates cytokine-dependent transcriptional regulation of p27(KIP1).
Mol Cell Biol.
2000;20:9138-9148 24. Naruse I, Hoshino H, Dobashi K, Minato K, Saito R, Mori M. Over-expression of p27kip1 induces growth arrest and apoptosis mediated by changes of pRb expression in lung cancer cell lines. Int J Cancer. 2000;88:377-383[CrossRef][Medline] [Order article via Infotrieve]. 25. Woltman AM, Fijter JW, Kamerling SWA, Paul LC, Daha MR, Van Kooten C. The effect of calcineurin inhibitors and corticosteroids on the differentiation of human dendritic cells. Eur J Immunol. 2000;30:1807-1812[CrossRef][Medline] [Order article via Infotrieve]. 26. Fallaux FJ, Kranenburg O, Cramer SJ, et al. Characterization of 911: a new helper cell line for the titration and propagation of early region 1-deleted adenoviral vectors. Hum Gene Ther. 1996;7:215-222[Medline] [Order article via Infotrieve].
27.
Rea D, Schagen FH, Hoeben RC, et al.
Adenoviruses activate human dendritic cells without polarization toward a T-helper type 1-inducing subset.
J Virol.
1999;73:10245-10253
28.
Sallusto F, Lanzavecchia A.
Efficient presentation of soluble antigen by cultured human dendritic cells is maintained by granulocyte/macrophage colony-stimulating factor plus interleukin 4 and downregulated by tumor necrosis factor alpha.
J Exp Med.
1994;179:1109-1118
29.
Chao JR, Wang JM, Lee SF, et al.
mcl-1 is an immediate-early gene activated by the granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling pathway and is one component of the GM-CSF viability response.
Mol Cell Biol.
1998;18:4883-4898
30.
Al Shami A, Mahanna W, Naccache PH.
Granulocyte-macrophage colony-stimulating factor-activated signaling pathways in human neutrophils: selective activation of Jak2, Stat3, and Stat5b.
J Biol Chem.
1998;273:1058-1063 31. Sato N, Sakamaki K, Terada N, Arai K, Miyajima A. Signal transduction by the high-affinity GM-CSF receptor: two distinct cytoplasmic regions of the common beta subunit responsible for different signaling. EMBO J. 1993;12:4181-4189[Medline] [Order article via Infotrieve]. 32. Kinoshita T, Yokota T, Arai K, Miyajima A. Suppression of apoptotic death in hematopoietic cells by signalling through the IL-3/GM-CSF receptors. EMBO J. 1995;14:266-275[Medline] [Order article via Infotrieve].
33.
Ardeshna KM, Pizzey AR, Devereux S, Khwaja A.
The PI3 kinase, p38 SAP kinase, and NF-kappaB signal transduction pathways are involved in the survival and maturation of lipopolysaccharide-stimulated human monocyte-derived dendritic cells.
Blood.
2000;96:1039-1046
34.
Reynisdottir I, Polyak K, Iavarone A, Massague J.
Kip/Cip and Ink4 Cdk inhibitors cooperate to induce cell cycle arrest in response to TGF-beta.
Genes Dev.
1995;9:1831-1845 35. Kato JY, Matsuoka M, Polyak K, Massague J, Sherr CJ. Cyclic AMP-induced G1 phase arrest mediated by an inhibitor (p27Kip1) of cyclin-dependent kinase 4 activation. Cell. 1994;79:487-496[CrossRef][Medline] [Order article via Infotrieve]. 36. Kiyokawa H, Kineman RD, Manova-Todorova KO, et al. Enhanced growth of mice lacking the cyclin-dependent kinase inhibitor function of p27(Kip1). Cell. 1996;85:721-732[CrossRef][Medline] [Order article via Infotrieve].
37.
Kozopas KM, Yang T, Buchan HL, Zhou P, Craig RW.
MCL1, a gene expressed in programmed myeloid cell differentiation, has sequence similarity to BCL2.
Proc Natl Acad Sci U S A.
1993;90:3516-3520
38.
Sedlak TW, Oltvai ZN, Yang E, et al.
Multiple Bcl-2 family members demonstrate selective dimerizations with Bax.
Proc Natl Acad Sci U S A.
1995;92:7834-7838
39.
Ohta K, Iwai K, Kasahara Y, et al.
Immunoblot analysis of cellular expression of Bcl-2 family proteins, Bcl-2, Bax, Bcl-X and Mcl-1, in human peripheral blood and lymphoid tissues.
Int Immunol.
1995;7:1817-1825 40. Krajewski S, Bodrug S, Krajewska M, et al. Immunohistochemical analysis of Mcl-1 protein in human tissues: differential regulation of Mcl-1 and Bcl-2 protein production suggests a unique role for Mcl-1 in control of programmed cell death in vivo. Am J Pathol. 1995;146:1309-1319[Abstract].
41.
Yang T, Kozopas KM, Craig RW.
The intracellular distribution and pattern of expression of Mcl-1 overlap with, but are not identical to, those of Bcl-2.
J Cell Biol.
1995;128:1173-1184
42.
Wang JM, Chao JR, Chen W, Kuo ML, Yen JJ, Yang-Yen HF.
The antiapoptotic gene mcl-1 is up-regulated by the phosphatidylinositol 3-kinase/Akt signaling pathway through a transcription factor complex containing CREB.
Mol Cell Biol.
1999;19:6195-6206
43.
Zhou P, Qian L, Bieszczad CK, et al.
Mcl-1 in transgenic mice promotes survival in a spectrum of hematopoietic cell types and immortalization in the myeloid lineage.
Blood.
1998;92:3226-3239 44. Schubert KM, Duronio V. Distinct roles for extracellular-signal-regulated protein kinase (ERK) mitogen-activated protein kinases and phosphatidylinositol 3-kinase in the regulation of Mcl-1 synthesis. Biochem J. 2001;356:473-480[CrossRef][Medline] [Order article via Infotrieve].
45.
Liu H, Perlman H, Pagliari LJ, Pope RM.
Constitutively activated Akt-1 is vital for the survival of human monocyte-differentiated macrophages: role of Mcl-1, independent of nuclear factor (NF)-kappaB, Bad, or caspase activation.
J Exp Med.
2001;194:113-126
46.
Dhodapkar MV, Steinman RM, Krasovsky J, Munz C, Bhardwaj N.
Antigen-specific inhibition of effector T cell function in humans after injection of immature dendritic cells.
J Exp Med.
2001;193:233-238 47. Thomson AW, Lu L. Dendritic cells as regulators of immune reactivity: implications for transplantation. Transplantation. 1999;68:1-8[Medline] [Order article via Infotrieve]. 48. Fairchild PJ, Waldmann H. Dendritic cells and prospects for transplantation tolerance. Curr Opin Immunol. 2000;12:528-535[CrossRef][Medline] [Order article via Infotrieve]. 49. Tarte K, Klein B. Dendritic cell-based vaccine: a promising approach for cancer immunotherapy. Leukemia. 1999;13:653-663[CrossRef][Medline] [Order article via Infotrieve]. 50. Banchereau J, Schuler-Thurner B, Palucka AK, Schuler G. Dendritic cells as vectors for therapy. Cell. 2001;106:271-274[CrossRef][Medline] [Order article via Infotrieve].
© 2003 by The American Society of Hematology.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
 |
|
  B. M. Janelsins, A. R. Mathers, O. A. Tkacheva, G. Erdos, W. J. Shufesky, A. E. Morelli, and A. T. Larregina Proinflammatory tachykinins that signal through the neurokinin 1 receptor promote survival of dendritic cells and potent cellular immunity Blood, March 26, 2009; 113(13): 3017 - 3026. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T Weichhart and M D Saemann The PI3K/Akt/mTOR pathway in innate immune cells: emerging therapeutic applications Ann Rheum Dis, December 1, 2008; 67(Suppl_3): iii70 - iii74. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Reichardt, C. Durr, D. von Elverfeldt, E. Juttner, U. V. Gerlach, M. Yamada, B. Smith, R. S. Negrin, and R. Zeiser Impact of Mammalian Target of Rapamycin Inhibition on Lymphoid Homing and Tolerogenic Function of Nanoparticle-Labeled Dendritic Cells following Allogeneic Hematopoietic Cell Transplantation J. Immunol., October 1, 2008; 181(7): 4770 - 4779. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. R. Turnquist, T. L. Sumpter, A. Tsung, A. F. Zahorchak, A. Nakao, G. J. Nau, F. Y. Liew, D. A. Geller, and A. W. Thomson IL-1{beta}-Driven ST2L Expression Promotes Maturation Resistance in Rapamycin-Conditioned Dendritic Cells J. Immunol., July 1, 2008; 181(1): 62 - 72. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. T. Woodland, C. J. Fox, M. R. Schmidt, P. S. Hammerman, J. T. Opferman, S. J. Korsmeyer, D. M. Hilbert, and C. B. Thompson Multiple signaling pathways promote B lymphocyte stimulator dependent B-cell growth and survival Blood, January 15, 2008; 111(2): 750 - 760. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Kakazu, N. Kanno, Y. Ueno, and T. Shimosegawa Extracellular Branched-Chain Amino Acids, Especially Valine, Regulate Maturation and Function of Monocyte-Derived Dendritic Cells J. Immunol., November 15, 2007; 179(10): 7137 - 7146. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 U. A. Hasan, C. Caux, I. Perrot, A.-C. Doffin, C. Menetrier-Caux, G. Trinchieri, M. Tommasino, and J. Vlach Cell proliferation and survival induced by Toll-like receptors is antagonized by type I IFNs PNAS, May 8, 2007; 104(19): 8047 - 8052. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Cutler, S. Li, V. T. Ho, J. Koreth, E. Alyea, R. J. Soiffer, and J. H. Antin Extended follow-up of methotrexate-free immunosuppression using sirolimus and tacrolimus in related and unrelated donor peripheral blood stem cell transplantation Blood, April 1, 2007; 109(7): 3108 - 3114. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Peponi, E. Drakos, G. Reyes, V. Leventaki, G. Z. Rassidakis, and L. J. Medeiros Activation of Mammalian Target of Rapamycin Signaling Promotes Cell Cycle Progression and Protects Cells from Apoptosis in Mantle Cell Lymphoma Am. J. Pathol., December 1, 2006; 169(6): 2171 - 2180. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Utsugi, K. Dobashi, T. Ishizuka, T. Kawata, T. Hisada, Y. Shimizu, A. Ono, and M. Mori Rac1 Negatively Regulates Lipopolysaccharide-Induced IL-23 p19 Expression in Human Macrophages and Dendritic Cells and NF-{kappa}B p65 trans Activation Plays a Novel Role J. Immunol., October 1, 2006; 177(7): 4550 - 4557. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Kriehuber, W. Bauer, A.-S. Charbonnier, D. Winter, S. Amatschek, D. Tamandl, N. Schweifer, G. Stingl, and D. Maurer Balance between NF-{kappa}B and JNK/AP-1 activity controls dendritic cell life and death Blood, July 1, 2005; 106(1): 175 - 183. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Biecker, A. De Gottardi, M. Neef, M. Unternahrer, V. Schneider, M. Ledermann, H. Sagesser, S. Shaw, and J. Reichen Long-Term Treatment of Bile Duct-Ligated Rats with Rapamycin (Sirolimus) Significantly Attenuates Liver Fibrosis: Analysis of the Underlying Mechanisms J. Pharmacol. Exp. Ther., June 1, 2005; 313(3): 952 - 961. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. J. Hagenbeek, M. Naspetti, F. Malergue, F. Garcon, J. A. Nunes, K. B.J.M. Cleutjens, J. Trapman, P. Krimpenfort, and H. Spits The Loss of PTEN Allows TCR {alpha}{beta} Lineage Thymocytes to Bypass IL-7 and Pre-TCR-mediated Signaling J. Exp. Med., October 4, 2004; 200(7): 883 - 894. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Woltman, N. Schlagwein, S. W. van der Kooij, and C. van Kooten The Novel Cyclophilin-Binding Drug Sanglifehrin A Specifically Affects Antigen Uptake Receptor Expression and Endocytic Capacity of Human Dendritic Cells J. Immunol., May 15, 2004; 172(10): 6482 - 6489. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. L. Christian, R. L. Lee, S. J. McLeod, A. E. Burgess, A. H. Y. Li, M. Dang-Lawson, K. B. L. Lin, and M. R. Gold Activation of the Rap GTPases in B Lymphocytes Modulates B Cell Antigen Receptor-induced Activation of Akt but Has No Effect on MAPK Activation J. Biol. Chem., October 24, 2003; 278(43): 41756 - 41767. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. H. Antin, H. T. Kim, C. Cutler, V. T. Ho, S. J. Lee, D. B. Miklos, E. P. Hochberg, C. J. Wu, E. P. Alyea, and R. J. Soiffer Sirolimus, tacrolimus, and low-dose methotrexate for graft-versus-host disease prophylaxis in mismatched related donor or unrelated donor transplantation Blood, September 1, 2003; 102(5): 1601 - 1605. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|||||||
 |
 |
 |
 |
 |
 |
 |
 |
||
| Copyright © 2003 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
Top
Abstract
Introduction
B (NF-
6 M.
