![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
Vol. 14, Issue 8, 3378-3388, August 2003
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
* The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands;
Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
02115; and
Molecular Cell Biology, Free University Amsterdam 1007MB, Amsterdam, The
Netherlands
Submitted November 18, 2002;
Revised February 26, 2003;
Accepted March 13, 2003
Monitoring Editor: Jennifer Lippincott-Schwartz
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
The DC maturation-associated changes in MHC class II intracellular
distribution and trafficking have been well characterized
(Lanzavecchia and Sallusto,
2001
; Mellman and Steinman,
2001). In IMDCs, a majority of MHC class II molecules are stored
in a late endosomal/lysosomal compartment, called the MHC class II compartment
(MIIC) (Peters et al.,
1991), where peptide antigen loading onto MHC class II molecules
is proposed to occur (Watts,
1997). In mature DCs (MDCs), the MIIC is reorganized and peptide
antigen-loaded MHC class II molecules are efficiently transported in a
retrograde manner in tubular transport containers. These tubes pull out and
polarize toward specific T cells and fuse with the DC plasma membrane
(Turley et al., 2000;
Kleijmeer et al.,
2001). Internalization of MHC class II from the cell surface is
down-regulated upon maturation and the class II dimers become more stable on
the cell surface with an increased half-life
(Cella et al., 1997;
Pierre et al., 1997;
Turley et al., 2000).
These DC maturation-associated cellular changes contribute to efficient
activation of peptide antigen-specific, MHC class II-restricted T cells.
Human DC also prominently express CD1a, b, c, and d members of a distinct
lineage of MHC-like antigen-presenting, molecules. Unlike MHC class I and
class II molecules, which bind short peptides, CD1 molecules bind
(glyco-)lipid antigens in their hydrophobic cavity for presentation to the T
cell receptor complex of a variety of T cells that function against microbial
infection (Porcelli et al.,
1992; Beckman et al.,
1994; Sieling et al.,
1995; Zeng et al.,
1997; Jackman et al.,
1998; Gumperz and Brenner,
2001; Gadola et al.,
2002).
Like MHC class II molecules, CD1b and CD1c molecules can be detected in
lysosomal MIICs. By virtue of the tyrosine-based endosomal targeting sequence
in the cytoplasmic tail, CD1b and CD1c are internalized in clathrin-coated
pits and vesicles from the plasma membrane and distribute to endocytic
subcompartments, including the MIIC
(Peters et al., 1995;
Sugita et al., 1996,
2000). It has been shown that
AP3 is essential for proper targeting of CD1b molecules, whereas MHC class II
molecules traffic independent of AP3
(Briken et al., 2002;
Sugita et al., 2002).
When the cytoplasmic tyrosine in the tail is deleted, CD1b molecules are
unable to target to endocytic subcompartments and reside primarily at the PM.
Cytoplasmic targeting motifs can be classified based on common amino acid
sequences and the most common tyrosine-based motif is the YXX
motif in
which Y is the tyrosine residue, X any amino acid, and a bulky
hydrophobic residue. A list of relevant transmembrane molecules containing a
tyrosine-based motif is given in Table
1 (Honing et al.,
1996; Sugita et al.,
1999,
2000). In contrast, CD1a lacks
the tyrosine-based motif and is expressed abundantly on the plasma membrane
and in early recycling endosomes (Sugita
et al., 1999).
|
The striking changes in MHC class II intracellular trafficking and the lack of knowledge about CD1 lipid antigen presentation during DC maturation urged us to initiate the current study to address how CD1 trafficking might be altered upon maturation. Surprisingly, we found that CD1b and CD1c molecules segregated from the MHC class II molecules in the MIIC. Whereas MHC class II trafficked out of the MIIC, no such steady-state redistribution of CD1b and c molecules occurred. CD1b and CD1c molecules were primarily detected in late endocytic compartments, herein termed mature dendritic cell lysosome (MDL). We further show that independently of the DC maturation status, CD1b molecules are continuously endocytosed from the plasma membrane via clathrin-coated vesicles. The continued internalization of CD1b molecules probably prevents substantial increases of the surface levels for CD1b, resulting in a striking difference in changes in cell surface expression between the lipid-presenting CD1 molecules and the peptide presenting MHC class II molecules.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
). The cells were cultured in RPMI 1640 medium containing 10%
fetal calf serum, 10 mM HEPES, 2.8 mM L-glutamine, 0.8 mM
nonessential amino acids, 0.4 mM essential amino acids, 100 µg/ml
penicillin-streptomycin, 50 µM 2-Mercaptoethanol, 300 U/ml human
recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF)
(PeproTech, Rocky Hill, NJ), and 200 U/ml human recombinant interleukin-4
(IL-4) (PeproTech) for 6 d to generate CD1-positive immature DCs. Maturation
of the DCs was induced by addition of 1 µg/ml LPS (Salmonella abortus
equi; Sigma-Aldrich, St. Louis, MO).
Electron Microscopy
Monocytes were cultured in medium containing GM-CSF/IL-4 for 6 d, and the
cells were fixed before stimulation and at different time points (1, 2, 4, 8,
24, 40, and 48 h) after stimulation with LPS. As a control, cells remained in
GM-CSF and IL-4 for the different time points. Fixation was performed by
adding an equal volume of 4% paraformaldehyde, and 0.4% glutaraldehyde in
PIPES/HEPES/EGTA/magnesium buffer to the warm culture medium. Fixed cells were
collected, embedded, and processed for cryosectioning with a Leica FCS as
described previously (Peters and Hunziker,
2001). Samples were trimmed using a diamond Cryotrim 90 knife at
–100°C (Diatome, Biel, Switzerland), and ultrathin sections of 50 nm
were cut at –120°C by using an ultramicrotome cryo knife. Immunogold
labeling was performed using mouse monoclonal antibodies against CD1a
(10H3.9.3), CD1b (BCD1b2.1), and CD1c (F10/21A3) and rabbit polyclonal
antisera against MHC class II (
-chain;
Neefjes et al.,
1990), mannose 6-phosphate receptor (M6PR; a gift from Dr. V. Hsu,
Harvard Medical School, Boston, MA), early endosome antigen1 (EEA1) (PA1-063;
Affinity Bioreagents, Golden, CO), CD63 (M1544; CLB Amsterdam, Amsterdam, The
Netherlands), and lysosome-associated membrane protein 1 (LAMP1 931.1; a gift
from M. Fukuda, La Jolla Cancer Research, La Jolla, CA). Detection of bound
antibodies was performed directly using protein-A conjugated to 10-nm gold or
via rabbit anti-mouse bridging serum (DAKO, Glostrup, Denmark) and protein-A
conjugated to 15-nm gold (Electron Microscopy Laboratory, Utrecht University,
Utrecht, The Netherlands). Sections were studied using a CM10 and CM12
transmission electron microscope (Fei, Endhoven, The Netherlands).
Flow Cytometry
Flow cytometric analysis was performed as described previously
(Porcelli et al.,
1992). The antibodies (see "Electron Microscopy") were
detected using fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse
IgG/IgM (Jackson Immunoresearch Laboratories, West Grove, PA).
Endocytosis Assays
Measurement of the pinocytic capacity was performed by incubating
LPS-stimulated DC and unstimulated DC with FITC-conjugated dextran. First, it
was determined whether the uptake of dextran is saturable by incubating the
cells with increasing concentrations of dextran-FITC. Incubations were
performed for 1 h in 0.5 mg/ml dextran–FITC (Molecular Probes, Eugene,
OR) at 4°C to determine the portion of dextran that would bind to the
plasma membrane without being endocytosed. Incubation at 37°C for 1 h
allows the cells to pinocytose the dextran, whereas control cells were kept on
ice.
The endocytic capacity via clathrin-coated pits was measured by using Alexa 488-conjugated transferrin (Molecular Probes) as a tracer. First, the optimal transferrin concentration was determined by titration to find the receptor saturation point. Immature and mature DCs were incubated in medium containing 10 µg/ml transferrin for 1 h at 4°C. Of these cells, one pool was incubated at 37°C for 1 h, whereas the control cells were kept on ice. The monocyte-derived DCs were then washed and analyzed by flow cytometry or fixed and processed for electron/fluorescence microscopy.
The internalization of CD1b molecules was studied using Fab fragments of CD1b monoclonal antibody BCD1b3.1. Fragments were cleaved using papain-agarose beads (Sigma-Aldrich) at 37°C, and undigested antibodies and Fc parts were purified from the Fab fragment solution by protein G-Sepharose beads. IMDCs and MDCs were collected and resuspended to a concentration of 2 x 107 cells/ml in cold IMDM medium supplemented with 10% fetal bovine serum and 6 µg/ml CD1b-specific Fab fragments. The cells were incubated on ice for 1 h to allow binding of the Fab fragments and subsequently washed three times and incubated at 37°C for various times (30, 60, and 120 min). Control samples were kept on ice for 120 min. Cells were transferred to ice to stop internalization and incubated for 30 min in FITC-conjugated goat anti-mouse IgG F(ab')2 (Pierce Chemical, Rockford, IL) to detect the Fab fragments on the cell surface by flow cytometry.
Chimeric Constructs
Construction of plasmids encoding chimeric CD1b molecules and transfection
in T2 cells is described previously
(Porcelli et al.,
1992). In all chimeric constructs, the luminal and transmembrane
portion remained of CD1b origin. Generation of the DNA construct has been
fully described (Sugita et al.,
2002), and its identity was confirmed by DNA sequencing. The
CD1b:CD63 tail-encoding plasmid was constructed in the pCEP4 expression vector
(Invitrogen, Carlsbad, CA) and transfected into human lymphoblastoid T2 cells
by electroporation. Selection was performed in the presence of 0.2 mg/ml
hygromycin B (Invitrogen), and positive cells were sorted by two cycles of
flow cytometric procedure.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
|
|
Segregation of CD1b and MHC Class II Molecules in Maturing DCs
DCs undergo dynamic cellular changes upon exposure to bacterial products,
such as LPS. These changes, collectively called DC maturation, include
efficient transport of peptide antigen-loaded MHC class II molecules from the
lysosomal MIIC to the plasma membrane. DC maturation-associated changes in
lysosomal morphology has been studied extensively at the ultrastructural
level, by using a LPS-stimulated murine DC cell line, in which tubulization of
the multivesicular MIIC extends toward the plasma membrane
(Kleijmeer et al.,
2001). However, these murine cells lack the expression of group 1
CD1 molecules and thus, it remained to be determined how CD1b and MHC class II
molecules might be differentially transported from lysosomes in maturing
DCs.
To investigate morphological changes in the multilamellar MIIC of maturing human DCs, monocyte-derived immature DCs were stimulated with LPS and harvested after 8 h for transmission electron microscopy. At this time point, the membrane lamellae tightly packed in concentric arrangement were appreciably loosened, and some membranes spread out and bud off to form electron-dense tubulo/vesicular structures that contained CD1b molecules, but often lacked the expression of MHC class II molecules (Figure 1B). MHC class II molecules tended to be excluded from the newly formed CD1b-containing vesicles, resulting in partial segregation of CD1b and MHC class II in these lysosomal compartments.
Distinct Steady-State Localization of CD1b and MHC Class II in Fully
Matured DCs
To evaluate late morphological changes in the MIIC in fully MDCs, IMDCs
were stimulated with LPS and harvested after 24 h for transmission electron
microscopy. At this time point, the internal membranes of the lysosomes
disappeared and the structure now was filled with electron-dense proteinaceous
content. The limiting membrane still contains CD1b, whereas virtually no MHC
class II molecules were detected (Figures
1C and
2). Considering the major
ultrastructural changes and the changes in the presence of resident molecules,
we herein propose to denote the altered mature DC
lysosome MDL. The limiting membrane of the MDL contained lysosomal
resident molecules LAMP1 (Figure
4). Less than 2% of the CD1b-containing compartments seemed to be
late endosomes as was shown by double labeling with late endosomal marker M6PR
(our unpublished data). We therefore concluded that the MDL represents a
subclass of lysosomal compartments.
|
|
Cytoplasmic Tail Determines Internal and Limiting Membrane Lysosomal
Localization of CD1b, CD1c, and CD63
In IMDCs, the localization of CD1b is on the limiting membrane of the
lysosomal MIIC, whereas the MHC class II is primarily on the internal
membranes. This difference in localization within the lysosome might determine
the localization after maturation in the MDL. Because the internal membranes
are lost in MDL, it is possible that only the molecules that form the limiting
membrane of the lysosomes in IMDC are present in the MDL. Other lysosomal
residents such as CD63 and LAMP1 seem to be localized preferentially to the
internal and the limiting membranes of MIICs, respectively
(Table 2). In contrast to CD1b,
CD63, and LAMP1, CD1c molecules are almost equally distributed over the
internal and limiting membrane domains. The specific enrichment of molecules
on the limiting membrane could be caused by the targeting information present
in their cytoplasmic tails. CD1b, CD1c, LAMP1, and CD63 all have similar
tyrosine motifs in their cytoplasmic tails that is believed to target these
molecules to lysosomes (Table
1). It is unknown whether the cytoplasmic motif also determines
the microanatomic localization within the lysosome. In contrast to the
tyrosine motifs, the lysosomal targeting of MHC class II is dependent on
several factors, including the dileucine targeting signal on the beta chain
and of the invariant chain. Herein, we analyzed the role of the CD1b
cytoplasmic tail in sublocalization in lysosomes. First, we generated chimeras
of CD1b, in which the cytoplasmic tail is exchanged for the tail of CD63,
which preferentially localizes to the internal membranes of the MIIC. Also,
tail chimeras of CD1b with CD1a and CD1c were evaluated to determine whether
CD1b chimera's remained at the limiting membrane. As a control, we determined
the localization of endogenous CD63.
The results showed that the localization of CD1b wild-type and endogenous CD63 is comparable with the distribution determined in IMDC. CD1b molecules with the CD1b tail are targeted to the limiting membrane of the lysosomes. Both the CD63 and the CD1c tail chimeric constructs target CD1b more prominently to the internal membranes (Figure 3). The CD1b/CD1a tail chimera was found in early endosomal compartments and not in lysosomes. These results demonstrate that the cytoplasmic tail of CD1b determines the targeting of CD1b molecules to the limiting membrane of the lysosome.
|
Localization on the Internal Membranes of Lysosomes Does Not
Determine Trafficking during DC Maturation
We next asked whether prior sublocalization in the internal or limiting
membranes of lysosomes determines localization after DC maturation. If the
internal membranes of the MIIC with MHC class II and its other molecules such
as CD63 are all relocated after maturation, one would predict that CD63 would
be absent from the MDL. However, immunogold localization of CD63 demonstrated
its abundant presence on the electron-dense LAMP1-positive structures in MDC
(Figure 4B). Thus, molecules
present on the internal membranes of the MIIC can also be detected on the MDL.
Also, CD1c molecules could be detected in these compartments but CD1a was not
(Figures 2 and
5). Apparently, MHC class II
molecules follow a different subcellular pathway in mature dendritic cells
than CD1b, CD1c, CD63, or LAMP1. The segregation of the pathway might be at
the level of the plasma membrane by constant internalization of CD1b, CD1c,
CD63, and LAMP1.
|
CD1 Continues to Be Internalized from the Plasma Membrane in
Clathrin-Coated Vesicles to a Similar Degree before and after Maturation
Besides localization to lysosomal MIICs, CD1b and CD1c were detected in
early endocytic structures in IMDCs, suggesting internalization from the
plasma membrane. However, previous studies on LPS-stimulated DCs have shown a
sharp overall reduction of endocytic capacity after DC maturation
(Inaba et al., 1993;
Sallusto et al.,
1995). Thus, we wished to determine whether clathrin-mediated
endocytosis was blocked after maturation of DC. Internalization of transferrin
conjugated with a fluorescent probe and internalization of CD1b detected with
Fab-fragments against CD1b were used as markers for clathrin-mediated
endocytosis in both MDC and IMDC. As a control, the fluid phase pinocytic
capacity of MDC and IMDC was evaluated using fluorescent-labeled dextran. As
expected, the uptake of the pinocytic marker dextran was reduced dramatically
after DC maturation (Figure
6A). In contrast, the endocytosis of transferrin was not affected
and remained at a constant level (Figure
6B). Also, we determined the localization of the endocytosed
transferrin in the cells by using immunofluorescence and as expected, observed
that the transferrin almost totally colocalized with EEA1 and transferrin
receptor (TfR) (our unpublished data). Importantly, the plasma membrane levels
of the Fab-fragments recognizing CD1b decreased in a similar manner during
incubation at 37°C, in the absence or presence of LPS, suggesting equal
internalization rates in MDC and IMDC
(Figure 6C).
|
Next, using cryoimmunogold electron microscopy we determined the
steady-state localization of CD1a, CD1b, and CD1c molecules to early endocytic
compartments in IMDC and MDC. We noted that in contrast to the MIIC, no
apparent change in the structure of the early endosomes was observed. CD1b and
CD1c but not MHC class II were detected in structures morphologically similar
to early endosomes, clathrin-coated pits, and coated vesicles in IMDCs
(Sugita et al., 1996)
and MDCs (Figure 5B). To ensure
that these structures were early endosomes, colocalization studies with the
TfR and EEA1 were performed. Both markers were detected in these
CD1b-containing compartments. Early endosomes (immunogold labeled with
antibodies against EEA1) in both unstimulated and LPS-stimulated DCs was
counted, and the percentage in which colocalization with CD1b or CD1c occurred
was determined. These percentages demonstrated that the amount of EEA-positive
early endosomes in which CD1b or CD1c is present has not changed after
maturation. Also, for CD1a localization, no quantifiable difference was
noticed (our unpublished data). In IMDC and MDC, CD1a expression remained
restricted to the plasma membrane and early endocytic tubulovesicular
structures. Thus, we detected no differences in the occurrence of CD1
molecules in the early endocytic structures in mature compared with immature
DCs, confirming the internalization data using fluorescent probes. Together,
these studies emphasize that in contrast to MHC class II, CD1b (and c)
molecules continue to be mainly in lysosomes, despite the drastic changes that
occur in these structures. Such persistence in lysosomes, even after DC
maturation, may be accounted for in part by the continued internalization from
the cell surface.
No Up-Regulation of CD1 Cell Surface Expression after DC
Maturation
Maturation of DCs has been shown to induce increased levels of MHC class II
expression on the cell surface. Because the subcellular trafficking of CD1
molecules after maturation seems to differ dramatically from the MHC class II
pathway, involving lysosomes and early endocytic structures, the effect of
maturation on cell surface levels of CD1 was determined. IMDC were stimulated
with LPS to develop into MDC. After LPS stimulation, virtually all the cells
strikingly up-regulated the surface expression of CD83, one of the most
reliable markers for DC maturation, confirming that all cells obtained in our
experiments were MDCs (Figure
7). These cells also expressed markedly increased levels of MHC
class II molecules on the cell surface. In contrast, up-regulation of cell
surface expression was not readily detected for CD1 molecules. The surface
expression of CD1a was apparently slightly down-regulated, whereas that of
CD1b and CD1c was not changed after LPS stimulation. Similarly, the surface
expression of LAMP1 and CD63 remained low and was not significantly altered.
These data demonstrate that despite the fact that MHC class II, CD1b, CD1c,
LAMP1, and CD63 were expressed in the same lysosomal compartments in IMDC, the
up-regulation of surface expression after DC maturation was detected only for
MHC class II, but not for other lysosomal residents. This finding further
underscores how intracellular trafficking pathways of CD1b and CD1c differ
from MHC class II.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
It has already been shown that the internal storage of MHC class II
molecules is relocated to the cell surface where the MHC molecules reside with
increased stability (Cella et al.,
1997; Pierre et al.,
1997; Turley et al.,
2000). In addition, it was shown that the internalization of MHC
class II molecules in mature DCs is largely blocked after LPS stimulation
(Kleijmeer et al.,
2001). The blockage of MHC class II internalization on matured
cells has, in part, been explained by a decreased rate of total endocytosis in
LPS-maturated DC (Cella et al.,
1997). Indeed, we confirmed that the uptake of FITC-dextran was
decreased after maturation. However, receptor-mediated endocytosis detected by
the uptake of transferrin by its receptor, revealed no statistical difference
between MDCs and IMDCs. Importantly, we found that the internalization rate of
CD1b in IMDCs and MDCs also was similar. Consistent with these results, it has
previously been shown that maturation of DCs caused no decrease in
clathrin-coated pits and vesicles (Garrett
et al., 2000). These results indicate that
clathrin-mediated endocytosis is unimpaired in MDCs, enabling the cells to
internalize along the clathrin-coated pit pathway. The internalization must be
selective and discriminate between molecules that stay on the surface (like
MHC class II) and molecules that need to be internalized. Because the surface
levels of CD1b and CD1c do not change appreciably, we suggest that CD1b and
CD1c are internalized at the same rate as their delivery to the plasma
membrane. The unchanged presence of CD1b and CD1c in coated vesicles and early
endosomes both before and after maturation supports no substantial difference
in their rate of internalization.
The present study, however, cannot distinguish whether these lysosomal molecules are retained in the lysosome during the process of maturation or accumulated after internalization from the plasma membrane. The transition of CD63 from the internal membranes of the MIIC to the limiting membrane in the MDL suggests that the molecules are not stably at one location.
In conclusion, our studies demonstrate that CD1b and CD1c segregate from MHC class II after DC stimulation. The different CD1 isoforms and MHC class II molecules are present on the cell surface and will interact with T cells at this site. It has been assumed that professional antigen-presenting cells such as the DCs consume their antigens or pathogens in the peripheral tissues and process them into presentable antigens so that DCs can interact with the T cells in lymphoid tissue. However, the continuous recycling of the CD1 molecules suggests that the lipid antigens may be loaded in CD1 both during mature and immature stages. Therefore, presentation of lipid antigens might occur in immature DCs at the peripheral tissues were T cells reside and precede MHC class II presentation, and continue after the DC matures and travels to the lymph node. Antigen presentation by MHC class II may be focused on the later stages of the adaptive immune response and require DC maturation to function. In contrast, CD1 is likely to function on DCs that are capable of sampling and presenting lipid antigens throughout their maturational life span.
|
ACKNOWLEDGMENTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
|
Footnotes |
|---|
Corresponding author. E-mail address:
p.peters{at}nki.nl.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
Briken, V., Jackman, R.M., Dasgupta, S., Hoening, S., and Porcelli, S.A. (2002). Intracellular trafficking pathway of newly synthesized CD1b molecules. EMBO J. 21, 825–834.[CrossRef][Medline]
Cella, M., Engering, A., Pinet, V., Pieters, J., and Lanzavecchia, A. (1997). Inflammatory stimuli induce accumulation of MHC class II complexes on dendritic cells. Nature 388, 782–787.[CrossRef][Medline]
Gadola, S.D., Zaccai, N.R., Harlos, K., Shepherd, D., Castro-Palomino, J.C., Ritter, G., Schmidt, R.R., Jones, E.Y., and Cerundolo, V. (2002). Structure of human CD1b with bound ligands at 2.3 A, a maze for alkyl chains. Nat. Immunol. 3, 721–726.[Medline]
Garrett, W.S., Chen, L.M., Kroschewski, R., Ebersold, M., Turley, S., Trombetta, S., Galan, J.E., and Mellman, I. (2000). Developmental control of endocytosis in dendritic cells by Cdc42. Cell 102, 325–334.[CrossRef][Medline]
Gumperz, J.E., and Brenner, M.B. (2001). CD1-specific T cells in microbial immunity. Curr. Opin. Immunol. 13, 471–478.[CrossRef][Medline]
Honing, S., Griffith, J., Geuze, H.J., and Hunziker, W. (1996). The tyrosine-based lysosomal targeting signal in lamp-1 mediates sorting into Golgi-derived clathrin-coated vesicles. EMBO J. 15, 5230–5239.[Medline]
Inaba, K., Inaba, M., Naito, M., and Steinman, R.M.
(1993). Dendritic cell progenitors phagocytose particulates,
including bacillus Calmette-Guerin organisms, and sensitize mice to
mycobacterial antigens in vivo. J. Exp. Med.
178,
479–488.
Jackman, R.M., Stenger, S., Lee, A., Moody, D.B., Rogers, R.A., Niazi, K.R., Sugita, M., Modlin, R.L., Peters, P.J., and Porcelli, S.A. (1998). The tyrosine-containing cytoplasmic tail of CD1b is essential for its efficient presentation of bacterial lipid antigens. Immunity 8, 341–351.[CrossRef][Medline]
Kleijmeer, M., et al. (2001). Reorganization
of multivesicular bodies regulates MHC class II antigen presentation by
dendritic cells. J. Cell Biol.
155,
53–63.
Lanzavecchia, A., and Sallusto, F. (2001). Regulation of T cell immunity by dendritic cells. Cell 106, 263–266.[CrossRef][Medline]
Mellman, I., and Steinman, R.M. (2001). Dendritic cells: specialized and regulated antigen processing machines. Cell 106, 255–258.[CrossRef][Medline]
Neefjes, J.J., Stollorz, V., Peters, P.J., Geuze, H.J., and Ploegh, H.L. (1990). The biosynthetic pathway of MHC class II but not class I molecules intersects the endocytic route. Cell 61, 171–183.[CrossRef][Medline]
Peters, P.J., and Hunziker, W. (2001). Subcellular localization of Rab17 by cryo-immunogold electron microscopy in epithelial cells grown on polycarbonate filters. Methods Enzymol. 329, 210–225.[Medline]
Peters, P.J., Neefjes, J.J., Oorschot, V., Ploegh, H.L., and Geuze, H.J. (1991). Segregation of MHC class II molecules from MHC class I molecules in the Golgi complex for transport to lysosomal compartments [see comments]. Nature 349, 669–676.[CrossRef][Medline]
Peters, P.J., Raposo, G., Neefjes, J.J., Oorschot, V.,
Leijendekker, R.L., Geuze, H.J., and Ploegh, H.L. (1995). Major
histocompatibility complex class II compartments in human B lymphoblastoid
cells are distinct from early endosomes. J. Exp. Med.
182,
325–334.
Pierre, P., Turley, S.J., Gatti, E., Hull, M., Meltzer, J., Mirza, A., Inaba, K., Steinman, R.M., and Mellman, I. (1997). Developmental regulation of MHC class II transport in mouse dendritic cells. Nature 388, 787–792.[CrossRef][Medline]
Porcelli, S., Morita, C.T., and Brenner, M.B. (1992). CD1b restricts the response of human CD4–8-T lymphocytes to a microbial antigen. Nature 360, 593–597.[CrossRef][Medline]
Sallusto, F., Cella, M., Danieli, C., and Lanzavecchia, A.
(1995). Dendritic cells use macropinocytosis and the mannose
receptor to concentrate macromolecules in the major histocompatibility complex
class II compartment: downregulation by cytokines and bacterial products.
J. Exp. Med. 182,
389–400.
Sieling, P.A., Chatterjee, D., Porcelli, S.A., Prigozy, T.I.,
Mazzaccaro, R.J., Soriano, T., Bloom, B.R., Brenner, M.B., Kronenberg, M., and
Brennan, P.J. (1995). CD1-restricted T cell recognition of
microbial lipoglycan antigens. Science
269,
227–230.
Sugita, M., Cao, X., Watts, G.F., Rogers, R.A., Bonifacino, J.S., and Brenner, M.B. (2002). Failure of trafficking and antigen presentation by CD1 in AP-3-deficient cells. Immunity 16, 697–706.[CrossRef][Medline]
Sugita, M., Grant, E.P., van Donselaar, E., Hsu, V.W., Rogers, R.A., Peters, P.J., and Brenner, M.B. (1999). Separate pathways for antigen presentation by CD1 molecules. Immunity 11, 743–752.[CrossRef][Medline]
Sugita, M., Jackman, R.M., van Donselaar, E., Behar, S.M., Rogers, R.A., Peters, P.J., Brenner, M.B., and Porcelli, S.A. (1996). Cytoplasmic tail-dependent localization of CD1b antigen-presenting molecules to MIICs. Science 273, 349–352.[Abstract]
Sugita, M., van Der, W.N., Rogers, R.A., Peters, P.J., and Brenner,
M.B. (2000). CD1c molecules broadly survey the endocytic system.
Proc. Natl. Acad. Sci. USA 97,
8445–8450.
Turley, S.J., Inaba, K., Garrett, W.S., Ebersold, M., Unternaehrer,
J., Steinman, R.M., and Mellman, I. (2000). Transport of
peptide-MHC class II complexes in developing dendritic cells.
Science 288,
522–527.
Watts, C. (1997). Capture and processing of exogenous antigens for presentation on MHC molecules. Annu. Rev. Immunol. 15, 821–850.[CrossRef][Medline]
Zeng, Z., Castano, A.R., Segelke, B.W., Stura, E.A., Peterson,
P.A., and Wilson, I.A. (1997). Crystal structure of mouse CD1: an
MHC-like fold with a large hydrophobic binding groove. Science
277,
339–345.
This article has been cited by other articles:
|
|
 |
|
  D. L. Hava, N. van der Wel, N. Cohen, C. C. Dascher, D. Houben, L. Leon, S. Agarwal, M. Sugita, M. van Zon, S. C. Kent, et al. Evasion of peptide, but not lipid antigen presentation, through pathogen-induced dendritic cell maturation PNAS, August 12, 2008; 105(32): 11281 - 11286. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Cernadas, M. Sugita, N. van der Wel, X. Cao, J. E. Gumperz, S. Maltsev, G. S. Besra, S. M. Behar, P. J. Peters, and M. B. Brenner Lysosomal Localization of Murine CD1d Mediated by AP-3 Is Necessary for NK T Cell Development J. Immunol., October 15, 2003; 171(8): 4149 - 4155. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
) and
LPS-maturated DCs (
). After internalization time of 30, 60, and 120 min,
the average and the SE of relative mean fluorescence intensity are given.
Monocyte-derived DCs of five different donors were used for five independent
experiments. At t = 0, the labeling was not optimal most likely due to low
temperature, and therefore the first measurement at 30 min is used to start
calculating the graphs. The rate of internalization of the Fab-labeled CD1b
molecules is not statistically different before and after maturation. (D)
Percentages of early endosomes positive for CD1b or CD1c in IMDCs and MDCs. At
least 40 different cells were used for detection of early endosomes that were
classified as such using EEA1 labeling.