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Abstract
Professional antigen presenting cells, such as dendritic cells, are effective in activating T lymphocytes due to their unique ability to present antigens in the context of both MHC class I and II molecules. After successful loading with antigenic peptides MHC class II molecules traffic from the late endosomal loading compartment to the plasma membrane to exert their function of presenting peptides to T helper lymphocytes. Various processes play a role in this event, which are only partly understood to date. The following protocols demonstrate a strategy of how to integrate high throughput datasets to select candidates possibly involved in MHC class II transport for in depth studies. A combination of proteomics, RNA interference and biochemical experimentation can uncover novel pathways regulating transport processes in primary dendritic cells.
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Affiliation(s)
- Petra Paul
- Department of Cell Biology II, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Jacques Neefjes
- Department of Cell Biology II, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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52
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Bergmann H, Yabas M, Short A, Miosge L, Barthel N, Teh CE, Roots CM, Bull KR, Jeelall Y, Horikawa K, Whittle B, Balakishnan B, Sjollema G, Bertram EM, Mackay F, Rimmer AJ, Cornall RJ, Field MA, Andrews TD, Goodnow CC, Enders A. B cell survival, surface BCR and BAFFR expression, CD74 metabolism, and CD8- dendritic cells require the intramembrane endopeptidase SPPL2A. ACTA ACUST UNITED AC 2012; 210:31-40. [PMID: 23267016 PMCID: PMC3549710 DOI: 10.1084/jem.20121076] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mice lacking activity of the intramembrane protease SPPL2A exhibit humoral immunodeficiency and lack mature B cell subsets. Druggable proteins required for B lymphocyte survival and immune responses are an emerging source of new treatments for autoimmunity and lymphoid malignancy. In this study, we show that mice with an inactivating mutation in the intramembrane protease signal peptide peptidase–like 2A (SPPL2A) unexpectedly exhibit profound humoral immunodeficiency and lack mature B cell subsets, mirroring deficiency of the cytokine B cell–activating factor (BAFF). Accumulation of Sppl2a-deficient B cells was rescued by overexpression of the BAFF-induced survival protein B cell lymphoma 2 (BCL2) but not BAFF and was distinguished by low surface BAFF receptor and IgM and IgD B cell receptors. CD8-negative dendritic cells were also greatly decreased. SPPL2A deficiency blocked the proteolytic processing of CD74 MHC II invariant chain in both cell types, causing dramatic build-up of the p8 product of Cathepsin S and interfering with earlier steps in CD74 endosomal retention and processing. The findings illuminate an important role for the final step in the CD74–MHC II pathway and a new target for protease inhibitor treatment of B cell diseases.
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Affiliation(s)
- Hannes Bergmann
- Ramaciotti Immunization Genomics Laboratory, John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
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53
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Bourgeois-Daigneault MC, Thibodeau J. Identification of a novel motif that affects the conformation and activity of the MARCH1 E3 ubiquitin ligase. J Cell Sci 2012; 126:989-98. [PMID: 23264739 DOI: 10.1242/jcs.117804] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
MARCH1, a member of the membrane-associated RING-CH family of E3 ubiquitin ligases, regulates antigen presentation by downregulating the cell surface expression of Major Histocompatibility Complex class II and CD86 molecules. MARCH1 is a transmembrane protein that exposes both its N- and C-terminus to the cytoplasm. We have conducted a structure-function analysis of its two cytoplasmic tails to gain insights into the trafficking of MARCH1 in the endocytic pathway. Fusion of the N-terminal portion of MARCH1 to a type II transmembrane reporter molecule revealed that this cytoplasmic tail contains endosomal sorting motifs. The C-terminal domain also appears to contain intracellular sorting signals because it reduced surface expression of a type I transmembrane reporter molecule. Mutation of the two putative C-terminal tyrosine-based sorting signals did not affect the activity of human MARCH1; however, it did reduce its incorporation into exosomes. Moreover, site-directed mutagenesis pointed to a functional C-terminal 221VQNC224 sequence that affects the spatial organization of the two cytoplasmic regions. This motif is also found in other RING-type E3 ubiquitin ligases, such as parkin. Altogether, these findings highlight the complex regulation of MARCH1 trafficking in the endocytic pathway as well as the intricate interactions between its cytoplasmic tails.
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54
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Finzi A, Perlman M, Bourgeois-Daigneault MC, Thibodeau J, Cohen ÉA. Major histocompatibility complex class-II molecules promote targeting of human immunodeficiency virus type 1 virions in late endosomes by enhancing internalization of nascent particles from the plasma membrane. Cell Microbiol 2012; 15:809-22. [PMID: 23170932 DOI: 10.1111/cmi.12074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 11/08/2012] [Accepted: 11/14/2012] [Indexed: 12/15/2022]
Abstract
Productive assembly of human immunodeficiency virus type 1 (HIV-1) takes place, primarily, at the plasma membrane. However, depending on the cell types, a significant proportion of nascent virus particles are internalized and routed to late endosomes. We previously reported that expression of human leucocyte antigen (HLA)-DR promoted a redistribution of Gag in late endosomes and an increased detection of mature virions in these compartments in HeLa and human embryonic kidney 293T model cell lines. Although this redistribution of Gag resulted in a marked decrease of HIV-1 release, the underlying mechanism remained undefined. Here, we provide evidence that expression of HLA-DR at the cell surface induces a redistribution of mature Gag products into late endosomes by enhancing nascent HIV-1 particle internalization from the plasma membrane through a process that relies on the presence of intact HLA-DR α and β-chain cytosolic tails. These findings raise the possibility that major histocompatibility complex class-II molecules might influence endocytic events at the plasma membrane and as a result promote endocytosis of progeny HIV-1 particles.
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Affiliation(s)
- Andrés Finzi
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
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55
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Mantegazza AR, Magalhaes JG, Amigorena S, Marks MS. Presentation of phagocytosed antigens by MHC class I and II. Traffic 2012; 14:135-52. [PMID: 23127154 DOI: 10.1111/tra.12026] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 11/01/2012] [Accepted: 11/06/2012] [Indexed: 12/15/2022]
Abstract
Phagocytosis provides innate immune cells with a mechanism to take up and destroy pathogenic bacteria, apoptotic cells and other large particles. In some cases, however, peptide antigens from these particles are preserved for presentation in association with major histocompatibility complex (MHC) class I or class II molecules in order to stimulate antigen-specific T cells. Processing and presentation of antigens from phagosomes presents a number of distinct challenges relative to antigens internalized by other means; while bacterial antigens were among the first discovered to be presented to T cells, analyses of the cellular mechanisms by which peptides from phagocytosed antigens assemble with MHC molecules and by which these complexes are then expressed at the plasma membrane have lagged behind those of conventional model soluble antigens. In this review, we cover recent advances in our understanding of these processes, including the unique cross-presentation of phagocytosed antigens by MHC class I molecules, and in their control by signaling modalities in phagocytic cells.
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Affiliation(s)
- Adriana R Mantegazza
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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56
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Niu YS, Wang MX, Liang S, Zhou F, Miao YG. Expression and localization of silkworm adaptor protein complex-1 subunits, which were down-regulated post baculovirus infection. Mol Biol Rep 2012; 39:10775-83. [PMID: 23053975 DOI: 10.1007/s11033-012-1971-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 10/01/2012] [Indexed: 12/17/2022]
Abstract
Adaptor protein complexes (APs) function as vesicle coat components in different membrane traffic pathways. In this study the subunits of adaptor protein complex-1 (AP-1) of silkworm Bombyx mori were molecularly characterized. All coding genes for the four subunits were cloned and sequenced. Phylogenic tree for each adaptin was constructed and all subunits were found to be conserved in respective group among organisms. The mRNA expression pattern for each adaptin was similar among tissues. Alternative splicing event was observed in genes encoding both the heavy chain gamma and beta adaptin and the light chain subunit, which could generate other possible adaptin forms. GFP-tagged fusion proteins indicated that AP-1 located in the peripheral plasma area. Furthermore, the BmNPV infection in B. mori cells had differentiated effect on the expression level of AP-1 subunits.
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Affiliation(s)
- Yan-Shan Niu
- Key Laboratory of Animal Virology of Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China
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57
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Chen F, Meng F, Pan L, Xu F, Liu X, Yu W. Boosting immune response with the invariant chain segments via association with non-peptide binding region of major histocompatibility complex class II molecules. BMC Immunol 2012; 13:55. [PMID: 23016601 PMCID: PMC3517428 DOI: 10.1186/1471-2172-13-55] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 09/17/2012] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Based on binding of invariant chain (Ii) to major histocompatibility complex (MHC) class II molecules to form complexes, Ii-segment hybrids, Ii-key structure linking an epitope, or Ii class II-associated invariant chain peptide (CLIP) replaced with an epitope were used to increase immune response. It is currently unknown whether the Ii-segment cytosolic and transmembrane domains bind to the MHC non-peptide binding region (PBR) and consequently influence immune response. To investigate the potential role of Ii-segments in the immune response via MHC II/peptide complexes, a few hybrids containing Ii-segments and a multiepitope (F306) from Newcastle disease virus fusion protein (F) were constructed, and their binding effects on MHC II molecules and specific antibody production were compared using confocal microscopy, immunoprecipitation, western blotting and animal experiments. RESULTS One of the Ii-segment/F306 hybrids, containing ND (Asn-Asp) outside the F306 in the Ii-key structure (Ii-key/F306/ND), neither co-localized with MHC II molecules on plasma membrane nor bound to MHC II molecules to form complexes. However, stimulation of mice with the structure produced 4-fold higher antibody titers compared with F306 alone. The two other Ii-segment/F306 hybrids, in which the transmembrane and cytosolic domains of Ii were linked to this structure (Cyt/TM/Ii-key/F306/ND), partially co-localized on plasma membrane with MHC class II molecules and weakly bound MHC II molecules to form complexes. They induced mice to produce approximately 9-fold higher antibody titers compared with F306 alone. Furthermore, an Ii/F306 hybrid (F306 substituting CLIP) co-localized well with MHC II molecules on the membrane to form complexes, although it increased antibody titer about 3-fold relative to F306 alone. CONCLUSIONS These results suggest that Ii-segments improve specific immune response by binding to the non-PBR on MHC class II molecules and enabling membrane co-localization with MHC II molecules, resulting in the formation of relatively stable MHC II/peptide complexes on the plasma membrane, and signal transduction.
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Affiliation(s)
- Fangfang Chen
- Key Laboratory of Zoonoses of Anhui Province, Anhui Agricultural University, 130 Changjiang West Road, Hefei 230036, China
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58
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Buroker NE, Huang JY, Barboza J, Ledee DR, Eastman RJ, Reinecke H, Ning XH, Bassuk JA, Portman MA. The adaptor-related protein complex 2, alpha 2 subunit (AP2α2) gene is a peroxisome proliferator-activated receptor cardiac target gene. Protein J 2012; 31:75-83. [PMID: 22160327 DOI: 10.1007/s10930-011-9379-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A peroxisome proliferator-actived receptor (PPAR) response element (RE) in the promoter region of the adaptor-related protein complex 2, alpha 2 subunit (AP2α2) of mouse heart has been identified. The steroid hormone nuclear PPARs and the retinoid X receptors (RXRs) are important transcriptional factors that regulate gene expression, cell differentiation and lipid metabolism. They form homo- (RXR) and hetero- (PPAR-RXR) dimers that bind DNA at various REs. The AP2α2 gene is part of complex and process that transports lipids and proteins from the plasma membrane to the endosomal system. A PPAR activator (Wy14643) and DMSO (vehicle) was introduced into control and δ337T thyroid hormone receptor (TRβ1) transgenic mice. Heart tissue was extracted and AP2α2 gene expression was compared using Affymetrix expression arrays and qRT PCR among four groups [control, control with Wy14643, δ337T TRβ1 and δ337T TRβ1 with Wy14643]. The gene expression of AP2α2 in the Wy14643 control and transgenic mouse groups was significantly up regulated over the vehicle mouse groups in both the array (p < 0.01) and qRT PCR (p < 0.01) studies. Duplex oligo DNAs containing the PPAR/RXR motif (AGGTCA/TCCAGT) from the AP2α2 promoter were used in EMSA to verify binding of the PPAR and RXR receptors to their REs. pGL4.0 [Luc] constructs of the AP2α2 promoter with and without the PPAR/RXR motifs were co-transfected with mouse PPARα, β or γ1 into HepG2 cells and used in lucerifase assays to verify gene activation. In conclusion our study revealed that PPARα regulates the mouse cardiac AP2α2 gene in both the control and transgenic mouse.
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Affiliation(s)
- Norman E Buroker
- Department of Cardiology, Seattle Children's Research Institute, Seattle, WA 98101, USA.
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59
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Towards a systems understanding of MHC class I and MHC class II antigen presentation. Nat Rev Immunol 2011; 11:823-36. [PMID: 22076556 DOI: 10.1038/nri3084] [Citation(s) in RCA: 1207] [Impact Index Per Article: 92.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The molecular details of antigen processing and presentation by MHC class I and class II molecules have been studied extensively for almost three decades. Although the basic principles of these processes were laid out approximately 10 years ago, the recent years have revealed many details and provided new insights into their control and specificity. MHC molecules use various biochemical reactions to achieve successful presentation of antigenic fragments to the immune system. Here we present a timely evaluation of the biology of antigen presentation and a survey of issues that are considered unresolved. The continuing flow of new details into our understanding of the biology of MHC class I and class II antigen presentation builds a system involving several cell biological processes, which is discussed in this Review.
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60
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Towards a systems understanding of MHC class I and MHC class II antigen presentation. Nat Rev Immunol 2011. [PMID: 22076556 DOI: 10.1038/nri3084.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The molecular details of antigen processing and presentation by MHC class I and class II molecules have been studied extensively for almost three decades. Although the basic principles of these processes were laid out approximately 10 years ago, the recent years have revealed many details and provided new insights into their control and specificity. MHC molecules use various biochemical reactions to achieve successful presentation of antigenic fragments to the immune system. Here we present a timely evaluation of the biology of antigen presentation and a survey of issues that are considered unresolved. The continuing flow of new details into our understanding of the biology of MHC class I and class II antigen presentation builds a system involving several cell biological processes, which is discussed in this Review.
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61
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ten Broeke T, van Niel G, Wauben MHM, Wubbolts R, Stoorvogel W. Endosomally stored MHC class II does not contribute to antigen presentation by dendritic cells at inflammatory conditions. Traffic 2011; 12:1025-36. [PMID: 21518167 DOI: 10.1111/j.1600-0854.2011.01212.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Major histocompatibility complex (MHC) class II (MHCII) is constitutively expressed by immature dendritic cells (DC), but has a short half-life as a consequence of its transport to and degradation in lysosomes. For its transfer to lysosomes, MHCII is actively sorted to the intraluminal vesicles (ILV) of multivesicular bodies (MVB), a process driven by its ubiquitination. ILV have, besides their role as an intermediate compartment in lysosomal transfer, also been proposed to function as a site for MHCII antigen loading and temporal storage. In that scenario, DC would recruit antigen-loaded MHCII to the cell surface in response to a maturation stimulus by allowing ILV to fuse back with the MVB delimiting membrane. Other studies, however, explained the increase in cell surface expression during DC maturation by transient upregulation of MHCII synthesis and reduced sorting of newly synthesized MHCII to lysosomes. Here, we have characterized the relative contributions from the biosynthetic and endocytic pathways and found that the vast majority of antigen-loaded MHCII that is stably expressed at the plasma membrane by mature DC is synthesized after exposure to inflammatory stimuli. Pre-existing endosomal MHCII contributed only when it was not yet sorted to ILV at the moment of DC activation. Together with previous records, our current data are consistent with a model in which passage of MHCII through ILV is not required for antigen loading in maturing DC and in which sorting to ILV in immature DC provides a one-way ticket for lysosomal degradation.
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Affiliation(s)
- Toine ten Broeke
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM, The Netherlands
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62
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Xie L, Qiao X, Wu Y, Tang J. β-Arrestin1 mediates the endocytosis and functions of macrophage migration inhibitory factor. PLoS One 2011; 6:e16428. [PMID: 21283538 PMCID: PMC3026819 DOI: 10.1371/journal.pone.0016428] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 12/16/2010] [Indexed: 12/21/2022] Open
Abstract
Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine, regulating inflammatory and immune responses. MIF binds to cell surface receptor CD74, resulting in both rapid and sustained ERK activation. It was reported that MIF-induced rapid ERK activation requires its co-receptor CD44. But the exact mechanism underlying sustained ERK activation is not well understood. In the current study, we described a detailed mechanism of MIF mediated sustained ERK activation. We found that β-arrestin1, a scaffold protein involved in the activation of the MAPK cascade, interacts with CD74 upon MIF stimulation, resulting in CD74-mediated MIF endocytosis in a chlorpromazine (CPZ)-sensitive manner. β-arrestin1 is also involved in endocytotic MIF signaling, leading to sustained ERK activation. Therefore β-arrestin1 plays a central role in coupling MIF endocytosis to sustained ERK activation.
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Affiliation(s)
- Lishi Xie
- Center for Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, People's Republic of China
- Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaohang Qiao
- Center for Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, People's Republic of China
- Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Yanfang Wu
- Center for Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Jie Tang
- Center for Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, People's Republic of China
- * E-mail:
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63
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Landsverk OJB, Barois N, Gregers TF, Bakke O. Invariant chain increases the half-life of MHC II by delaying endosomal maturation. Immunol Cell Biol 2010; 89:619-29. [PMID: 21116285 DOI: 10.1038/icb.2010.143] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mounting adaptive immune responses requires the cell surface expression of major histocompatibility class II molecules (MHC II) loaded with antigenic peptide. However, in the absence of antigenic stimuli, the surface population of MHC II is highly dynamic and exhibits a high turnover. Several studies have focused on the regulation of MHC II, and it is now recognized that ubiquitination is one key mechanism operating in the turnover of MHC II in B cells and dendritic cells. Here, we describe how the invariant chain (Ii) can prolong the half-life of MHC II through its action on the endocytic pathway. We find that in cells expressing intermediate-to-high levels of Ii, the half-life of MHC II is increased, with MHC II accumulating in slowly-maturing endosomes. The accumulation in endosomes is not due to retention of new MHC II directed from the endoplasmatic reticulum, as also mature, not Ii associated, MHC II is preserved. We suggest that this alternative endocytic pathway induced by Ii would serve to enhance the rate, quantity and diversity of MHC II antigen presentation by concentrating MHC II into specialized compartments and reducing the need for new MHC II synthesis upon antigen encounter.
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Affiliation(s)
- Ole J B Landsverk
- Department of Molecular Biosciences, Centre for Immune Regulation, University of Oslo and Rikshospitalet, Oslo University Hospital Norway, Oslo, Norway
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64
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van den Hoorn T, Paul P, Jongsma MLM, Neefjes J. Routes to manipulate MHC class II antigen presentation. Curr Opin Immunol 2010; 23:88-95. [PMID: 21112200 DOI: 10.1016/j.coi.2010.11.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 11/02/2010] [Indexed: 11/28/2022]
Abstract
MHC class II molecules (MHC-II) present antigenic fragments acquired in the endocytic route to the immune system for recognition and activation of CD4+ T cells. This ignites a series of immune responses. MHC-II strongly correlates to most autoimmune diseases. Understanding the biology of MHC-II is therefore expected to translate into novel means of autoimmunity control or immune response improvement. Although the basic cell biology of MHC-II antigen presentation is well understood, many novel aspects have been uncovered in recent years including means of antigen delivery, preparation for MHC-II loading, transport processes and vaccination strategies. We will discuss past, present and future of these insights into the biology of MHC-II.
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Affiliation(s)
- Tineke van den Hoorn
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, Netherlands
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65
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Ubiquitination regulates MHC class II-peptide complex retention and degradation in dendritic cells. Proc Natl Acad Sci U S A 2010; 107:20465-70. [PMID: 21059907 DOI: 10.1073/pnas.1010990107] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The expression and turnover of MHC class II-peptide complexes (pMHC-II) on the surface of dendritic cells (DCs) is essential for their ability to activate CD4 T cells efficiently. The half-life of surface pMHC-II is significantly greater in activated (mature) DCs than in resting (immature) DCs, but the molecular mechanism leading to this difference remains unknown. We now show that ubiquitination of pMHC-II by the E3 ubiquitin ligase membrane-associated RING-CH 1 (March-I) regulates surface expression, intracellular distribution, and survival of pMHC-II in DCs. DCs isolated from March-I-KO mice express very high levels of pMHC-II on the plasma membrane even before DC activation. Although ubiquitination does not affect the kinetics of pMHC-II endocytosis from the surface of DCs, the survival of pMHC-II is enhanced in DCs obtained from March-I-deficient and MHC-II ubiquitination-mutant mice. Using pMHC-II-specific mAb, we show that immature DCs generate large amounts of pMHC-II that are remarkably stable under conditions in which pMHC-II ubiquitination is blocked. Thus, the cellular distribution and stability of surface pMHC-II in DCs is regulated by ubiquitin-dependent degradation of internalized pMHC-II.
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66
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Zwart W, Peperzak V, de Vries E, Keller AM, van der Horst G, Veraar EAM, Geumann U, Janssen H, Janssen L, Naik SH, Neefjes J, Borst J. The invariant chain transports TNF family member CD70 to MHC class II compartments in dendritic cells. J Cell Sci 2010; 123:3817-27. [DOI: 10.1242/jcs.068510] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
CD70 is a TNF-related transmembrane molecule expressed by mature dendritic cells (DCs), which present antigens to T cells via major histocompatibility complex (MHC) molecules. In DCs, CD70 localizes with MHC class II molecules in late endosomal vesicles, known as MHC class II compartments (MIICs). MIICs are transported to the immune synapse when a DC contacts an antigen-specific CD4+ T cell. Consequently, MHC class II and CD70 are simultaneously exposed to the T cell. Thereby, T-cell activation via the antigen receptor and CD70-mediated co-stimulation are synchronized, apparently to optimize the proliferative response. We report here that the invariant chain (Ii), a chaperone known to transport MHC class II to MIICs, performs a similar function for CD70. CD70 was found to travel by default to the plasma membrane, whereas Ii coexpression directed it to late endosomes and/or lysosomes. In cells containing the MHC class II presentation pathway, CD70 localized to MIICs. This localization relied on Ii, since transport of CD70 from the Golgi to MIICs was impeded in Ii-deficient DCs. Biophysical and biochemical studies revealed that CD70 and Ii participate in an MHC-class-II-independent complex. Thus, Ii supports transport of both MHC class II and CD70 to MIICs and thereby coordinates their delivery to CD4+ T cells.
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Affiliation(s)
- Wilbert Zwart
- Division of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Victor Peperzak
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Evert de Vries
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Anna M. Keller
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Gerda van der Horst
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Elise A. M. Veraar
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Ulf Geumann
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Hans Janssen
- Division of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Lennert Janssen
- Division of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Shalin H. Naik
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Jacques Neefjes
- Division of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Jannie Borst
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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67
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ten Broeke T, de Graaff A, van't Veld EM, Wauben MHM, Stoorvogel W, Wubbolts R. Trafficking of MHC class II in dendritic cells is dependent on but not regulated by degradation of its associated invariant chain. Traffic 2009; 11:324-31. [PMID: 20051049 DOI: 10.1111/j.1600-0854.2009.01024.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In dendritic cells (DC), newly synthesized MHCII is directed to endosomes by its associated invariant chain (Ii). Here, Ii is degraded after which MHCII is loaded with peptides. In immature DC, ubiquitination of peptide-loaded MHCII drives its sorting to lysosomes for degradation. Ubiquitination of MHCII is strongly reduced in response to inflammatory stimuli, resulting in increased expression of MHCII at the plasma membrane. Whether surface exposure of MHCII is also regulated during DC maturation by changing the rate of Ii degradation remained unresolved by conflicting results in the literature. We here pinpoint experimental problems that have contributed to these controversies and demonstrate that immature and mature DC degrade Ii equally efficient at proper culture conditions. Only when DC were cultured in glutamine containing media, endosome acidification and Ii degradation were restricted in immature DC and enhanced in response to lipopolysaccharide (LPS). These effects are caused by ammonia, a glutamine decomposition product. This artificial behavior could be prevented by culturing DC in media containing a stable dipeptide as glutamine source. We conclude that Ii degradation is a prerequisite for but not a rate limiting step in MHCII processing.
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Affiliation(s)
- Toine ten Broeke
- Department of Biochemistry and Cell Biology, Utrecht University, PO Box 80.176, NL-3508 TD Utrecht, The Netherlands
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Nakada-Tsukui K, Kobayashi Y, Watanabe N. Characterization of a cDNA encoding guinea pig I3 associated with the delayed-type hypersensitivity reaction. Zoolog Sci 2009; 26:617-22. [PMID: 19799512 DOI: 10.2108/zsj.26.617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To elucidate the molecular mechanisms involved in the delayed-type hypersensitivity (DTH) reaction, we performed a differential display analysis to identify genes whose expression was elevated in guinea pig DTH reaction-elicited skin-infiltrating cells. One of genes isolated was Identified as a guinea pig I3 gene that encodes a polypeptide of 125 amino acids. The amino acid sequence was above 90% identical to that of human, mouse, and rat I3 protein. Although I3 was originally Identified as a gene expressed in mouse brain, its mRNA was widely expressed in various guinea pig tissues and Immune cells such as spleen cells and macrophages, but was hardly detected in thymic cells. I3 protein was also detected in immune cells, except for thymic cells. As expected from the amino acid sequence, part of the I3 protein was located on the cell surface. Furthermore, green fluorescent protein-tagged I3 protein showed a particulate localization in the cytoplasm and partly colocalized with lysosomes and late endosomes, coincident with the presence of typical endosomal/ lysosomal-targeting motifs. These results suggested that I3 may be involved in trafficking via the plasma membrane or in granule-related functions.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Biomolecular Science, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
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69
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Landsverk OJB, Bakke O, Gregers TF. MHC II and the endocytic pathway: regulation by invariant chain. Scand J Immunol 2009; 70:184-93. [PMID: 19703008 DOI: 10.1111/j.1365-3083.2009.02301.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The major histocompatibility complex (MHC) class I and II molecules perform vital functions in innate and adaptive immune responses towards invading pathogens. MHC class I molecules load peptides in the endoplasmatic reticulum (ER) and display them to the T cell receptors (TcR) on CD8(+) T lymphocytes. MHC class II molecules (MHC II) acquire their peptides in endosomes and present these to the TcR on CD4+ T lymphocytes. They are vital for the generation of humoral immune responses. MHC II assembly in the ER and trafficking to endosomes is guided by a specialized MHC II chaperone termed the invariant chain (Ii). Ii self-associates into a trimer in the ER, this provides a scaffold for the assembly of three MHC II heterodimers and blocks their peptide binding grooves, thereby avoiding premature peptide binding. Ii then transports the nascent MHC II to more or less specialized compartment where they can load peptides derived from internalized pathogens.
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Affiliation(s)
- O J B Landsverk
- Centre for Immune Regulation, Department of Molecular Biosciences, University of Oslo, 0316 Oslo, Norway
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70
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Salmonella regulates polyubiquitination and surface expression of MHC class II antigens. Proc Natl Acad Sci U S A 2009; 106:14052-7. [PMID: 19666567 DOI: 10.1073/pnas.0906735106] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Salmonella typhimurium is a facultative pathogen capable of entering and replicating in both professional and non-professional antigen presenting cells. Control of infection requires MHC class II restricted CD4 T-helper cell responses. Here we show that Salmonella infection induced polyubiquitination of HLA-DR, a post-translational modification that led to removal of mature, peptide loaded, alphabeta dimers from the cell surface. Immature alphabetaIi complexes were unaffected. Surface expression of all class II isotypes, HLA-DP, -DQ, and -DR, was reduced in infected cells, but other cell-surface molecules that traffic through class II peptide loading compartments were unaffected. A Salmonella strain carrying a mutation in ssaV did not induce ubiquitination of class II, implicating Salmonella T3SS-2 effector proteins in the process. T3SS-2 effectors, with established or proposed roles in ubiquitination, were not required for class II down-regulation, suggesting that an additional T3SS-2 effector is involved in regulating MHC class II ubiquitination. Although recognized as a viral immune evasion strategy, here, we demonstrate that bacteria can control surface MHC expression through ubiquitination.
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71
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Gauvreau ME, Côté MH, Bourgeois-Daigneault MC, Rivard LD, Xiu F, Brunet A, Shaw A, Steimle V, Thibodeau J. Sorting of MHC class II molecules into exosomes through a ubiquitin-independent pathway. Traffic 2009; 10:1518-27. [PMID: 19566897 DOI: 10.1111/j.1600-0854.2009.00948.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Major histocompatibility complex class II (MHC-II) molecules accumulate in exocytic vesicles, called exosomes, which are secreted by antigen presenting cells. These vesicles are released following the fusion of multivesicular bodies (MVBs) with the plasma membrane. The molecular mechanisms regulating cargo selection remain to be fully characterized. As ubiquitination of the MHC-II beta-chain cytoplasmic tail has recently been demonstrated in various cell types, we sought to determine if this post-translational modification is required for the incorporation of MHC-II molecules into exosomes. First, we stably transfected HeLa cells with a chimeric HLA-DR molecule in which the beta-chain cytoplasmic tail is replaced by ubiquitin. Western blot analysis did not indicate preferential shedding of these chimeric molecules into exosomes. Next, we forced the ubiquitination of MHC-II in class II transactivator (CIITA)-expressing HeLa and HEK293 cells by transfecting the MARCH8 E3 ubiquitin ligase. Despite the almost complete downregulation of MHC-II from the plasma membrane, these molecules were not enriched in exosomes. Finally, site-directed mutagenesis of all cytoplasmic lysine residues on HLA-DR did not prevent inclusion into these vesicles. Taken together, these results demonstrate that ubiquitination of MHC-II is not a prerequisite for incorporation into exosomes.
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Affiliation(s)
- Marie-Elaine Gauvreau
- Laboratoire d'Immunologie Moléculaire, Département de Microbiologie et Immunologie, Université de Montréal, Québec, Canada
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72
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Affiliation(s)
- Adam C Berger
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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73
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A basic patch on alpha-adaptin is required for binding of human immunodeficiency virus type 1 Nef and cooperative assembly of a CD4-Nef-AP-2 complex. J Virol 2009; 83:2518-30. [PMID: 19129443 DOI: 10.1128/jvi.02227-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A critical function of the human immunodeficiency virus type 1 Nef protein is the downregulation of CD4 from the surfaces of infected cells. Nef is believed to act by linking the cytosolic tail of CD4 to the endocytic machinery, thereby increasing the rate of CD4 internalization. In support of this model, weak binary interactions between CD4, Nef, and the endocytic adaptor complex, AP-2, have been reported. In particular, dileucine and diacidic motifs in the C-terminal flexible loop of Nef have been shown to mediate binding to a combination of the alpha and sigma2 subunits of AP-2. Here, we report the identification of a potential binding site for the Nef diacidic motif on alpha-adaptin. This site comprises two basic residues, lysine-297 and arginine-340, on the alpha-adaptin trunk domain. The mutation of these residues specifically inhibits the ability of Nef to bind AP-2 and downregulate CD4. We also present evidence that the diacidic motif on Nef and the basic patch on alpha-adaptin are both required for the cooperative assembly of a CD4-Nef-AP-2 complex. This cooperativity explains how Nef is able to efficiently downregulate CD4 despite weak binary interactions between components of the tripartite complex.
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74
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Abstract
Viral protein U (Vpu) is encoded by one of several accessory genes of HIV-1. Like the accessory gene products Vif and Vpr, Vpu targets host proteins such as CD4 for degradation via the recruitment of cellular multi-subunit ubiquitin ligases. Vpu also forms ion channels in cellular membranes. Through one or both of these attributes, Vpu antagonizes host cell factors that restrict the release of progeny virions from infected cells. A key target of Vpu has recently been identified as the interferon-induced transmembrane protein BST-2/CD317 (tetherin), which restricts viral replication by retaining nascent virions on the cell surface. The counteraction of this host defense allows Vpu to be considered an antagonist of the innate immune response to viral infection.
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Affiliation(s)
- John C Guatelli
- Department of Medicine, University of California-San Diego and the San Diego Department of Veterans Affairs Healthcare System, 9500 Gilman Drive, La Jolla, CA 92093-0679, USA.
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75
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Endolysosomal phospholipidosis and cytosolic lipid droplet storage and release in macrophages. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:524-39. [PMID: 19146988 DOI: 10.1016/j.bbalip.2008.12.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 12/08/2008] [Accepted: 12/11/2008] [Indexed: 12/12/2022]
Abstract
This review summarizes the current knowledge of endolysosomal and cytoplasmic lipid storage in macrophages induced by oxidized LDL (Ox-LDL), enzymatically degraded LDL (E-LDL) and other atherogenic lipoprotein modifications, and their relation to the adapter protein 3 (AP-3) dependent ABCA1 and ABCG1 cellular lipid efflux pathways. We compare endolysosomal lipid storage caused either through drug induced phospholipidosis, inheritable endolysosomal and cytosolic lipid storage disorders and Ox-LDL or E-LDL induced phagosomal uptake and cytosolic lipid droplet storage in macrophages. Ox-LDL is resistant to rapid endolysosomal hydrolysis and is trapped within the endolysosomal compartment generating lamellar bodies which resemble the characteristics of phospholipidosis. Various inherited lysosomal storage diseases including sphingolipidosis, glycosphingolipidosis and cholesterylester storage diseases also present a phospholipidosis phenotype. In contrast E-LDL resembling coreless unesterified cholesterol enriched LDL-particles, with a multilamellar, liposome-like structure, lead to rapid phagosomal degradation and cytosolic lipid droplet accumulation. As a consequence the uptake of E-LDL through type I and type II phagocytosis leads to increased lipid droplet formation and moderate upregulation of ABCA1 and ABCG1 while uptake of Ox-LDL leads to a rapid expansion of the lysosomal compartment and a pronounced upregulation of the ABCA1/ABCG1/AP-3 lipid efflux pathway.
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76
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Robila V, Ostankovitch M, Altrich-VanLith ML, Theos AC, Drover S, Marks MS, Restifo N, Engelhard VH. MHC class II presentation of gp100 epitopes in melanoma cells requires the function of conventional endosomes and is influenced by melanosomes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2008; 181:7843-52. [PMID: 19017974 PMCID: PMC2659719 DOI: 10.4049/jimmunol.181.11.7843] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Many human solid tumors express MHC class II (MHC-II) molecules, and proteins normally localized to melanosomes give rise to MHC-II-restricted epitopes in melanoma. However, the pathways by which this response occurs have not been defined. We analyzed the processing of one such epitope, gp100(44-59), derived from gp100/Pmel17. In melanomas that have down-regulated components of the melanosomal pathway, but constitutively express HLA-DR*0401, the majority of gp100 is sorted to LAMP-1(high)/MHC-II(+) late endosomes. Using mutant gp100 molecules with altered intracellular trafficking, we demonstrate that endosomal localization is necessary for gp100(44-59) presentation. By depletion of the AP-2 adaptor protein using small interfering RNA, we demonstrate that gp100 protein internalized from the plasma membrane to such endosomes is a major source for gp100(44-59) epitope production. The gp100 trapped in early endosomes gives rise to epitopes that are indistinguishable from those produced in late endosomes but their production is less sensitive to inhibition of lysosomal proteases. In melanomas containing melanosomes, gp100 is underrepresented in late endosomes, and accumulates in stage II melanosomes devoid of MHC-II molecules. The gp100(44-59) presentation is dramatically reduced, and processing occurs entirely in early endosomes or stage I melanosomes. This occurrence suggests that melanosomes are inefficient Ag-processing compartments. Thus, melanoma de-differentiation may be accompanied by increased presentation of MHC-II restricted epitopes from gp100 and other melanosome-localized proteins, leading to enhanced immune recognition.
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Affiliation(s)
- Valentina Robila
- Department of Microbiology and Carter Immunology Center, University of Virginia School of Medicine, Charlottesville VA 22908
| | - Marina Ostankovitch
- Department of Microbiology and Carter Immunology Center, University of Virginia School of Medicine, Charlottesville VA 22908
| | - Michelle L. Altrich-VanLith
- Department of Microbiology and Carter Immunology Center, University of Virginia School of Medicine, Charlottesville VA 22908
| | - Alexander C. Theos
- Dept. of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia PA 19104
| | - Sheila Drover
- Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NF Canada A1B3V6
| | - Michael S. Marks
- Dept. of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia PA 19104
| | - Nicholas Restifo
- National Cancer Institute, National Institutes of Health Bethesda, MD 20892
| | - Victor H. Engelhard
- Department of Microbiology and Carter Immunology Center, University of Virginia School of Medicine, Charlottesville VA 22908
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77
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Sorting of lysosomal proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:605-14. [PMID: 19046998 DOI: 10.1016/j.bbamcr.2008.10.016] [Citation(s) in RCA: 583] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 10/07/2008] [Accepted: 10/30/2008] [Indexed: 11/24/2022]
Abstract
Lysosomes are composed of soluble and transmembrane proteins that are targeted to lysosomes in a signal-dependent manner. The majority of soluble acid hydrolases are modified with mannose 6-phosphate (M6P) residues, allowing their recognition by M6P receptors in the Golgi complex and ensuing transport to the endosomal/lysosomal system. Other soluble enzymes and non-enzymatic proteins are transported to lysosomes in an M6P-independent manner mediated by alternative receptors such as the lysosomal integral membrane protein LIMP-2 or sortilin. Sorting of cargo receptors and lysosomal transmembrane proteins requires sorting signals present in their cytosolic domains. These signals include dileucine-based motifs, DXXLL or [DE]XXXL[LI], and tyrosine-based motifs, YXXØ, which interact with components of clathrin coats such as GGAs or adaptor protein complexes. In addition, phosphorylation and lipid modifications regulate signal recognition and trafficking of lysosomal membrane proteins. The complex interaction of both luminal and cytosolic signals with recognition proteins guarantees the specific and directed transport of proteins to lysosomes.
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78
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Keyel PA, Thieman JR, Roth R, Erkan E, Everett ET, Watkins SC, Heuser JE, Traub LM. The AP-2 adaptor beta2 appendage scaffolds alternate cargo endocytosis. Mol Biol Cell 2008; 19:5309-26. [PMID: 18843039 DOI: 10.1091/mbc.e08-07-0712] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The independently folded appendages of the large alpha and beta2 subunits of the endocytic adaptor protein (AP)-2 complex coordinate proper assembly and operation of endocytic components during clathrin-mediated endocytosis. The beta2 subunit appendage contains a common binding site for beta-arrestin or the autosomal recessive hypercholesterolemia (ARH) protein. To determine the importance of this interaction surface in living cells, we used small interfering RNA-based gene silencing. The effect of extinguishing beta2 subunit expression on the internalization of transferrin is considerably weaker than an AP-2 alpha subunit knockdown. We show the mild sorting defect is due to fortuitous substitution of the beta2 chain with the closely related endogenous beta1 subunit of the AP-1 adaptor complex. Simultaneous silencing of both beta1 and beta2 subunit transcripts recapitulates the strong alpha subunit RNA interference (RNAi) phenotype and results in loss of ARH from endocytic clathrin coats. An RNAi-insensitive beta2-yellow fluorescent protein (YFP) expressed in the beta1 + beta2-silenced background restores cellular AP-2 levels, robust transferrin internalization, and ARH colocalization with cell surface clathrin. The importance of the beta appendage platform subdomain over clathrin for precise deposition of ARH at clathrin assembly zones is revealed by a beta2-YFP with a disrupted ARH binding interface, which does not restore ARH colocalization with clathrin. We also show a beta-arrestin 1 mutant, which engages coated structures in the absence of any G protein-coupled receptor stimulation, colocalizes with beta2-YFP and clathrin even in the absence of an operational clathrin binding sequence. These findings argue against ARH and beta-arrestin binding to a site upon the beta2 appendage platform that is later obstructed by polymerized clathrin. We conclude that ARH and beta-arrestin depend on a privileged beta2 appendage site for proper cargo recruitment to clathrin bud sites.
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Affiliation(s)
- Peter A Keyel
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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79
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Bunbury A, Potolicchio I, Maitra R, Santambrogio L. Functional analysis of monocyte MHC class II compartments. FASEB J 2008; 23:164-71. [PMID: 18815360 DOI: 10.1096/fj.08-109439] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Circulating monocytes, as dendritic cell and macrophage precursors, exhibit several functions usually associated with antigen-presenting cells, such as phagocytosis and presence of endosomal/lysosomal degradative compartments particularly enriched in Lamp-1, MHC class II molecules, and other proteins related to antigen processing and MHC class II loading [MHC class II compartments (MIICs)]. Ultrastructural analysis of these organelles indicates that, differently from the multivesicular bodies present in dendritic cells, in monocytes the MIICs are characterized by a single perimetral membrane surrounding an electron-dense core. Analysis of their content reveals enrichment in myeloperoxidase, an enzyme classically associated with azurophilic granules in granulocytes and mast cell secretory lysosomes. Elevation in intracellular free calcium levels in monocytes induced secretion of beta-hexosaminidase, cathepsins, and myeloperoxidase in the extracellular milieu; surface up-regulation of MHC class II molecules; and appearance of lysosomal resident proteins. The Ca(2+)-regulated surface transport mechanism of MHC class II molecules observed in monocytes is different from the tubulovesicular organization of the multivesicular bodies previously reported in dendritic cells and macrophages. Hence, in monocytes, MHC class II-enriched organelles combine degradative functions typical of lysosomes and regulated secretion typical of secretory lysosomes. More important, Ca(2+)-mediated up-regulation of surface MHC class II molecules is accompanied by extracellular release of lysosomal resident enzymes.
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Affiliation(s)
- Allyson Bunbury
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
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80
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van Niel G, Wubbolts R, Stoorvogel W. Endosomal sorting of MHC class II determines antigen presentation by dendritic cells. Curr Opin Cell Biol 2008; 20:437-44. [PMID: 18582577 DOI: 10.1016/j.ceb.2008.05.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 04/21/2008] [Accepted: 05/29/2008] [Indexed: 11/29/2022]
Affiliation(s)
- Guillaume van Niel
- Institut Curie, Centre National de la Recherche Scientifique-Unité Mixte de Recherche 144, Paris 75248, France.
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81
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Human immunodeficiency virus type 1 nef expression prevents AP-2-mediated internalization of the major histocompatibility complex class II-associated invariant chain. J Virol 2008; 82:8373-82. [PMID: 18596106 DOI: 10.1128/jvi.00670-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The lentiviral Nef protein has been studied extensively for its ability to induce the downregulation of several immunoreceptors on the surfaces of infected cells. However, Nef expression is unique in inducing highly effective upregulation of the major histocompatibility complex class II-associated chaperone invariant (Ii) chain complexes in different cell types. Under normal conditions, endocytosis of the Ii chain and other molecules, like the transferrin receptor and CD4, is rapid and AP-2 dependent. Human immunodeficiency virus type 1 (HIV-1) Nef expression strongly reduces the internalization of the Ii chain, enhances that of CD4, and does not modify transferrin uptake. The mutation of AP-2 binding motifs LL164 and DD174 in Nef leads to the inhibition of Ii chain upregulation. In AP-2-depleted cells, surface levels of the Ii chain are high and remain unmodified by Nef expression, further indicating that Nef regulates Ii chain internalization via the AP-2 pathway. Immunoprecipitation experiments revealed that the Ii chain can interact with Nef in a dileucine-dependent manner. Importantly, we have shown that Nef-induced CD4 downregulation and Ii chain upregulation are genetically distinguishable. We have identified natural nef alleles that have lost one of the two functions but not the other one. Moreover, we have characterized Nef mutant forms possessing a similar phenotype in the context of HIV-1 infection. Therefore, the Nef-induced accumulation of Ii chain complexes at the cell surface probably results from a complex mechanism leading to the impairment of AP-2-mediated endocytosis rather than from direct competition between Nef and the Ii chain for binding AP-2.
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82
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Competition model for upregulation of the major histocompatibility complex class II-associated invariant chain by human immunodeficiency virus type 1 Nef. J Virol 2008; 82:7758-67. [PMID: 18524831 DOI: 10.1128/jvi.02668-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Nef protein upregulates the expression of the invariant chain (Ii)/major histocompatibility complex class II (MHC-II) complex at the cell surface. This complex appears to reach the antigen-loading endosomal compartment at least in part via an indirect pathway in which it is internalized from the cell surface via the adaptor protein 2 (AP-2) complex. Here we provide evidence for a competition model to explain how Nef upregulates the expression of Ii at the cell surface. In this model, Nef and Ii compete for binding to AP-2. In support of this model, Nef decreased the rate of internalization of Ii from the cell surface. The AP-binding dileucine motif in Nef, ENTSLL(165), was necessary and sufficient for the upregulation of Ii. In addition, two leucine-based AP-binding motifs in the Ii cytoplasmic tail, DDQRDLI(8) and EQLPML(17), were critical for the efficient upregulation of Ii by Nef. Experiments using Nef variants in which the native dileucine-based sorting motif was replaced with similar motifs from cellular transmembrane proteins allowed modulation of AP-binding specificity. Analysis of these variants suggested that the binding of Nef to AP-2 is sufficient to upregulate Ii at the plasma membrane. Finally, interference with the expression of AP-2 caused an upregulation of Ii at the plasma membrane, and this decreased the effect of Nef. These data indicate that Nef usurps AP-2 complexes to dysregulate Ii trafficking and potentially interfere with antigen presentation in the context of MHC-II.
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83
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Walseng E, Bakke O, Roche PA. Major histocompatibility complex class II-peptide complexes internalize using a clathrin- and dynamin-independent endocytosis pathway. J Biol Chem 2008; 283:14717-27. [PMID: 18378669 DOI: 10.1074/jbc.m801070200] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Major histocompatibility complex (MHC) class II molecules (MHC-II) function by binding antigenic peptides and displaying these peptides on the surface of antigen presenting cells (APCs) for recognition by peptide-MHC-II (pMHC-II)-specific CD4 T cells. It is known that cell surface MHC-II can internalize, exchange antigenic peptides in endosomes, and rapidly recycle back to the plasma membrane; however, the molecular machinery and trafficking pathways utilized by internalizing/recycling MHC-II have not been identified. We now demonstrate that unlike newly synthesized invariant chain-associated MHC-II, mature cell surface pMHC-II complexes internalize following clathrin-, AP-2-, and dynamin-independent endocytosis pathways. Immunofluorescence microscopy of MHC-II expressing HeLa-CIITA cells, human B cells, and human DCs revealed that pMHC enters Arf6(+)Rab35(+)EHD1(+) tubular endosomes following endocytosis. These data contrast the internalization pathways followed by newly synthesized and peptide-loaded MHC-II molecules and demonstrates that cell surface pMHC-II internalize and rapidly recycle from early endocytic compartments in tubular endosomes.
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Affiliation(s)
- Even Walseng
- Experimental Immunology Branch, NCI, NIH, Bethesda, MD 20892, USA
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84
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Repass SL, Brady RJ, O'Halloran TJ. Dictyostelium Hip1r contributes to spore shape and requires epsin for phosphorylation and localization. J Cell Sci 2007; 120:3977-88. [PMID: 17971415 DOI: 10.1242/jcs.011213] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clathrin-coated pits assemble on the plasma membrane to select and sequester proteins within coated vesicles for delivery to intracellular compartments. Although a host of clathrin-associated proteins have been identified, much less is known regarding the interactions between clathrin-associated proteins or how individual proteins influence the function of other proteins. In this study, we present evidence of a functional relationship between two clathrin-associated proteins in Dictyostelium, Hip1r and epsin. Hip1r-null cells form fruiting bodies that yield defective spores that lack the organized fibrils typical of wild-type spores. This spore coat defect leads to formation of round, rather than ovoid, spores in Hip1r-null cells that exhibit decreased viability. Like Hip1r-null cells, epsin-null cells also construct fruiting bodies with round spores, but these spores are more environmentally robust. Double-null cells that harbor deletions in both epsin and Hip1r form fruiting bodies, with spores identical in shape and viability to Hip1r single-null cells. In the growing amoeba, Hip1r is phosphorylated and localizes to puncta on the plasma membrane that also contain epsin. Both the phosphorylation state and localization of Hip1r into membrane puncta require epsin. Moreover, expression of the N-terminal ENTH domain of epsin is sufficient to restore both the phosphorylation and the restricted localization of Hip1r within plasma membrane puncta. The results from this study reveal a novel interaction between two clathrin-associated proteins during cellular events in both growing and developing Dictyostelium cells.
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Affiliation(s)
- Shannon Lea Repass
- Department of Molecular Cell and Developmental Biology, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin TX 78712, USA
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85
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Arneson LS, Miller J. The chondroitin sulfate form of invariant chain trimerizes with conventional invariant chain and these complexes are rapidly transported from the trans-Golgi network to the cell surface. Biochem J 2007; 406:97-103. [PMID: 17492940 PMCID: PMC1948987 DOI: 10.1042/bj20070446] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Targeting of MHCII-invariant chain complexes from the trans-Golgi network to endosomes is mediated by two di-leucine-based signals present in the cytosolic domain of invariant chain. Generation of this endosomal targeting signal is also dependent on multimerization of the invariant chain cytosolic domain sequences, mediated through assembly of invariant chain into homotrimers. A small subset of invariant chain is modified by the addition of chondroitin sulfate and is expressed on the cell surface in association with MHCII. In the present study, we have followed the biosynthetic pathway and route of intracellular transport of this proteoglycan form of invariant chain. We found that the efficiency of chondroitin sulfate modification can be increased by altering the invariant chain amino acid sequence around Ser-201 to the xylosylation consensus sequence. Our results also indicate that, following sulfation, the proteoglycan form is transported rapidly from the trans-Golgi network to the cell surface and is degraded following internalization into an endocytic compartment. Invariant chain-chondroitin sulfate is present in invariant chain trimers that also include conventional non-proteoglycan forms of invariant chain. These data indicate that invariant chain-chondroitin sulfate-containing complexes are transported rapidly from the trans-Golgi network to the cell surface in spite of the presence of an intact endosomal localization signal. Furthermore, these results suggest that invariant chain-chondroitin sulfate may play an important role in the generation of cell-surface pools of invariant chain that can serve as receptors for CD44 and macrophage migration inhibitory factor.
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Affiliation(s)
- Lynne S Arneson
- Department of Biology, American University, Hurst Hall 101, 4400 Massachusetts Ave NW, Washington, DC 20016, USA.
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86
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Lubben NB, Sahlender DA, Motley AM, Lehner PJ, Benaroch P, Robinson MS. HIV-1 Nef-induced down-regulation of MHC class I requires AP-1 and clathrin but not PACS-1 and is impeded by AP-2. Mol Biol Cell 2007; 18:3351-65. [PMID: 17581864 PMCID: PMC1951775 DOI: 10.1091/mbc.e07-03-0218] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Major histocompatibility complex class I is down-regulated from the surface of human immunodeficiency virus (HIV)-1-infected cells by Nef, a virally encoded protein that is thought to reroute MHC-I to the trans-Golgi network (TGN) in a phosphofurin acidic cluster sorting protein (PACS) 1, adaptor protein (AP)-1, and clathrin-dependent manner. More recently, an alternative model has been proposed, in which Nef uses AP-1 to direct MHC-I to endosomes and lysosomes. Here, we show that knocking down either AP-1 or clathrin with small interfering RNA inhibits the down-regulation of HLA-A2 (an MHC-I isotype) by Nef in HeLa cells. However, knocking down PACS-1 has no effect, not only on Nef-induced down-regulation of HLA-A2 but also on the localization of other proteins containing acidic cluster motifs. Surprisingly, knocking down AP-2 actually enhances Nef activity. Immuno-electron microscopy labeling of Nef-expressing cells indicates that HLA-A2 is rerouted not to the TGN, but to endosomes. In AP-2-depleted cells, more of the HLA-A2 localizes to the inner vesicles of multivesicular bodies. We propose that depleting AP-2 potentiates Nef activity by altering the membrane composition and dynamics of endosomes and causing increased delivery of HLA-A2 to a prelysosomal compartment.
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Affiliation(s)
- Nienke B. Lubben
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | - Daniela A. Sahlender
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | - Alison M. Motley
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | - Paul J. Lehner
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | | | - Margaret S. Robinson
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
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87
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Malanga D, Barba P, Harris PE, Maffei A, Del Pozzo G. The active translation of MHCII mRNA during dendritic cells maturation supplies new molecules to the cell surface pool. Cell Immunol 2007; 246:75-80. [PMID: 17662701 DOI: 10.1016/j.cellimm.2007.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 06/11/2007] [Accepted: 06/12/2007] [Indexed: 11/24/2022]
Abstract
The transition of human dendritic cells (DCs) from the immature to the mature phenotype is characterized by an increased density of MHC class II (MHCII) molecules on the plasma membrane, a key requirement of their competence as professional antigen presenting cells (APCs). MHCII molecules on the cell surface derive from newly synthesized as well as from preexisting proteins. So far, all the studies done on DCs during maturation, to establish the relative contribution of newly synthesized MHCII molecules to the cell surface pool did not produced a clear, unified scenario. We report that, in human DCs stimulated ex vivo with LPS, the changes in the RNA accumulation specific for at least two MHCII genes (HLA-DRA and HLA-DQA1) due to transcriptional upregulation, is associated with the active translation at high rate of these transcripts. Our finding reveals that, across the 24h of the maturation process in human DCs, newly synthesized MHCII proteins are supplied to the APCs cell surface pool.
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Affiliation(s)
- Donatella Malanga
- Institute of Genetics and Biophysics "A. Buzzati-Traverso", CNR, Naples, Italy
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88
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van Niel G, Wubbolts R, Ten Broeke T, Buschow SI, Ossendorp FA, Melief CJ, Raposo G, van Balkom BW, Stoorvogel W. Dendritic cells regulate exposure of MHC class II at their plasma membrane by oligoubiquitination. Immunity 2007; 25:885-94. [PMID: 17174123 DOI: 10.1016/j.immuni.2006.11.001] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 11/13/2006] [Indexed: 11/24/2022]
Abstract
Dendritic cells (DCs) initiate adaptive immune responses by activating T cells via cognate interactions between MHC-peptide complexes and T cell receptors. In immature DCs, MHC class II is predominantly stored in late endocytic compartments, where it has a short half-life because of degradation. In contrast, mature DCs recruit MHC class II to the plasma membrane. We here demonstrate that in immature DCs, the beta-chain of MHC class II was oligoubiquitinated after proteolytic processing of the associated invariant chain in endosomes and that this modification was required for efficient endocytosis and sorting into luminal vesicles of multivesicular bodies. Ubiquitination of MHC class II was suppressed in lipopolysaccharide-activated DCs. Mutated MHC class II lacking its ubiquitination site was expressed at the plasma membrane, irrespective of DC maturation. Together, these data provide a molecular basis for the regulation of MHC class II-mediated antigen presentation by DCs.
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Affiliation(s)
- Guillaume van Niel
- Faculty of Veterinary Medicine, Department of Biochemistry & Cell Biology, Utrecht University, P.O. Box 80.176, NL-3508 TD, Utrecht, The Netherlands
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89
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Abstract
One more mechanism for regulating surface expression of MHC class II proteins in dendritic cells (an important process that regulates both tolerance and immunity) has been uncovered, polyubiquitination of Lys225 in the intracytoplasmic region and subsequent endocytosis and proteolysis (Omura-Hoshino et al., 2006; van Neil et al., 2006; Shin et al., 2006).
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Affiliation(s)
- Laura Santambrogio
- Department of Pathology, Albert Einstein College of Medicine, New York, New York 10461, USA
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90
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Matsuki Y, Ohmura-Hoshino M, Goto E, Aoki M, Mito-Yoshida M, Uematsu M, Hasegawa T, Koseki H, Ohara O, Nakayama M, Toyooka K, Matsuoka K, Hotta H, Yamamoto A, Ishido S. Novel regulation of MHC class II function in B cells. EMBO J 2007; 26:846-54. [PMID: 17255932 PMCID: PMC1794403 DOI: 10.1038/sj.emboj.7601556] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 12/20/2006] [Indexed: 11/09/2022] Open
Abstract
The presence of post-translational regulation of MHC class II (MHC II) under physiological conditions has been demonstrated recently in dendritic cells (DCs) that potently function as antigen-presenting cells (APCs). Here, we report that MARCH-I, an E3 ubiquitin ligase, plays a pivotal role in the post-translational regulation of MHC II in B cells. MARCH-I expression was particularly high in B cells, and the forced expression of MARCH-I induced the ubiquitination of MHC II. In B cells from MARCH-I-deficient mice (MARCH-I KO), the half-life of surface MHC II was prolonged and the ubiquitinated form of MHC II completely disappeared. In addition, MARCH-I-deficient B cells highly expressed exogenous antigen-loaded MHC II on their surface and showed high ability to present exogenous antigens. These results suggest that the function of MHC II in B cells is regulated through ubiquitination by MARCH-I.
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Affiliation(s)
- Yohei Matsuki
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Mari Ohmura-Hoshino
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Eiji Goto
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Masami Aoki
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Mari Mito-Yoshida
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Mika Uematsu
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Takanori Hasegawa
- Laboratory for Developmental Genetics, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Haruhiko Koseki
- Laboratory for Developmental Genetics, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Osamu Ohara
- Laboratory for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
- Kazusa DNA Research Institute, Kisarazu, Chiba, Japan
| | | | - Kiminori Toyooka
- RIKEN Plant Science Center, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Ken Matsuoka
- RIKEN Plant Science Center, Tsurumi-ku, Yokohama, Kanagawa, Japan
- Laboratory of Plant Nutrition, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka, Japan
| | - Hak Hotta
- Division of Microbiology, Department of Genome Sciences, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Akitsugu Yamamoto
- Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Satoshi Ishido
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan
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91
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David A, Tiveron MC, Defays A, Beclin C, Camosseto V, Gatti E, Cremer H, Pierre P. BAD-LAMP defines a subset of early endocytic organelles in subpopulations of cortical projection neurons. J Cell Sci 2007; 120:353-65. [PMID: 17215451 DOI: 10.1242/jcs.03316] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The brain-associated LAMP-like molecule (BAD-LAMP) is a new member of the family of lysosome associated membrane proteins (LAMPs). In contrast to other LAMPs, which show a widespread expression, BAD-LAMP expression in mice is confined to the postnatal brain and therein to neuronal subpopulations in layers II/III and V of the neocortex. Onset of expression strictly parallels cortical synaptogenesis. In cortical neurons, the protein is found in defined clustered vesicles, which accumulate along neurites where it localizes with phosphorylated epitopes of neurofilament H. In primary neurons, BAD-LAMP is endocytosed, but is not found in classical lysosomal/endosomal compartments. Modification of BAD-LAMP by addition of GFP revealed a cryptic lysosomal retention motif, suggesting that the cytoplasmic tail of BAD-LAMP is actively interacting with, or modified by, molecules that promote its sorting away from lysosomes. Analysis of BAD-LAMP endocytosis in transfected HeLa cells provided evidence that the protein recycles to the plasma membrane through a dynamin/AP2-dependent mechanism. Thus, BAD-LAMP is an unconventional LAMP-like molecule and defines a new endocytic compartment in specific subtypes of cortical projection neurons. The striking correlation between the appearance of BAD-LAMP and cortical synatogenesis points towards a physiological role of this vesicular determinant for neuronal function.
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Affiliation(s)
- Alexandre David
- Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Case 906, 13288 Marseille cedex 9, France.
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92
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Mwangi W, Brown WC, Splitter GA, Davies CJ, Howard CJ, Hope JC, Aida Y, Zhuang Y, Hunter BJ, Palmer GH. DNA vaccine construct incorporating intercellular trafficking and intracellular targeting motifs effectively primes and induces memory B- and T-cell responses in outbred animals. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:304-11. [PMID: 17215335 PMCID: PMC1828862 DOI: 10.1128/cvi.00363-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We developed a vaccine construct in which a BVP22 domain and an invariant-chain major histocompatibility complex class II-targeting motif capable of enhancing dendritic cell antigen uptake and presentation were fused to a sequence encoding a B- and T-cell antigen from the Anaplasma marginale major surface protein 1a and tested whether this construct would prime and expand immune responses in outbred calves. A single inoculation with this construct effectively primed the immune responses, as demonstrated by a significant enhancement of CD4(+) T-cell proliferation compared to that in calves identically inoculated but inoculated with a DNA construct lacking the targeting domains and compared to that in calves inoculated with an empty vector. These proliferative responses were mirrored by priming and expansion of gamma interferon-positive CD4(+) T cells and immunoglobulin G responses against the linked B-cell epitope. Priming by the single immunization induced memory that underwent rapid recall following reexposure to the antigen. These results demonstrate that DNA vaccines targeting key intercellular and intracellular events significantly enhance priming and expansion and support the feasibility of single-dose DNA immunization in outbred populations.
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Affiliation(s)
- Waithaka Mwangi
- Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164, USA.
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93
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Finzi A, Brunet A, Xiao Y, Thibodeau J, Cohen EA. Major histocompatibility complex class II molecules promote human immunodeficiency virus type 1 assembly and budding to late endosomal/multivesicular body compartments. J Virol 2006; 80:9789-97. [PMID: 16973583 PMCID: PMC1617259 DOI: 10.1128/jvi.01055-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) assembly, budding, and release occur mostly at the plasma membrane in T lymphocytes as well as in established nonlymphoid cell lines, while in macrophages these processes occur primarily in intracellular compartments that harbor late endosomal/multivesicular body (LE/MVB) markers, including human leukocyte antigen DR (HLA-DR). Major histocompatibility complex class II molecules (MHC-II), which are expressed in macrophages and activated T cells, have been previously reported to induce the formation of multilaminar and multivesicular endocytic MHC-II-like structures analogous to MVB upon their expression in HEK 293 cells. Here, we have examined the role of MHC-II in HIV-1 Gag targeting as well as in virus assembly and release. Expression of HLA-DR in nonlymphoid cell lines induced a relocation of Gag to intracellular compartments that harbored LE/MVB markers and increased the accumulation of viral particles assembling intracellularly. Consequently, viral production and release from the cell surface was found to be substantially decreased in HLA-DR-expressing cells. This process was specific, since it was not observed with HLA-DR molecules lacking their cytoplasmic tails, nor with structurally related but functionally distinct MHC-II molecules such as HLA-DM or HLA-DO. Importantly, virus released intracellularly in HLA-DR-expressing cells retained infectivity. Overall, these results suggest a role of MHC-II molecules in promoting HIV-1 assembly and budding to LE/MVB and raise the possibility that this activity might be part of a normal pathway of virus production in cell types physiologically expressing MHC-II molecules, such as macrophages.
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Affiliation(s)
- Andrés Finzi
- Unité de Rétrovirologie Humaine, Institut de Recherches Cliniques de Montréal, Montréal, Canada
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94
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Fattakhova G, Masilamani M, Borrego F, Gilfillan AM, Metcalfe DD, Coligan JE. The high-affinity immunoglobulin-E receptor (FcepsilonRI) is endocytosed by an AP-2/clathrin-independent, dynamin-dependent mechanism. Traffic 2006; 7:673-85. [PMID: 16637889 DOI: 10.1111/j.1600-0854.2006.00423.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Aggregation of the high-affinity immunoglobulin E (IgE) receptor (FcepsilonRI), expressed on mast cells and basophils, initiates the immediate hypersensitivity reaction. Aggregated FcepsilonRI has been reported to rapidly migrate to lipid rafts in RBL-2H3 cells. We confirmed that aggregated FcepsilonRI is found in the lipid raft fractions of cellular lysates. Furthermore, we show that the cross-linked FcepsilonRI remains associated with detergent-resistant structures upon internalization. Previous morphological studies have reported that aggregated FepsiloncRI is endocytosed via clathrin-coated pits, which in general are not lipid raft associated. To address this apparent discrepancy, we employed siRNA to suppress expression of components of the clathrin-mediated internalization machinery, namely, clathrin heavy chain, and the AP-2 (alpha-adaptin or mu2-subunit). Transferrin receptor (TfR) is endocytosed by a clathrin-mediated process and, as expected, each transfected siRNA caused a two to threefold elevation of TfR surface expression and almost completely inhibited its endocytosis. In contrast, there was no effect on surface expression levels of FcepsilonRI nor on the endocytosis of the dinitrophenyl-human serum albumin (DNP-HSA)/IgE/FcepsilonRI complex. On the contrary, internalization of DNP-HSA/IgE/FcepsilonRI was inhibited by overexpression of a dominant-negative dynamin mutant. We conclude that internalization of cross-linked FcRI does not require the AP-2/clathrin complex but is dynamin-dependent and may be lipid raft mediated.
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Affiliation(s)
- Gul'nar Fattakhova
- Receptor Cell Biology Section, Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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95
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Theos AC, Berson JF, Theos SC, Herman KE, Harper DC, Tenza D, Sviderskaya EV, Lamoreux ML, Bennett DC, Raposo G, Marks MS. Dual loss of ER export and endocytic signals with altered melanosome morphology in the silver mutation of Pmel17. Mol Biol Cell 2006; 17:3598-612. [PMID: 16760433 PMCID: PMC1525253 DOI: 10.1091/mbc.e06-01-0081] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pmel17 is a pigment cell-specific integral membrane protein that participates in the formation of the intralumenal fibrils upon which melanins are deposited in melanosomes. The Pmel17 cytoplasmic domain is truncated by the mouse silver mutation, which is associated with coat hypopigmentation in certain strain backgrounds. Here, we show that the truncation interferes with at least two steps in Pmel17 intracellular transport, resulting in defects in melanosome biogenesis. Human Pmel17 engineered with the truncation found in the mouse silver mutant (hPmel17si) is inefficiently exported from the endoplasmic reticulum (ER). Localization and metabolic pulse-chase analyses with site-directed mutants and chimeric proteins show that this effect is due to the loss of a conserved C-terminal valine that serves as an ER exit signal. hPmel17si that exits the ER accumulates abnormally at the plasma membrane due to the loss of a di-leucine-based endocytic signal. The combined effects of reduced ER export and endocytosis significantly deplete Pmel17 within endocytic compartments and delay proteolytic maturation required for premelanosome-like fibrillogenesis. The ER export delay and cell surface retention are also observed for endogenous Pmel17si in melanocytes from silver mice, within which Pmel17 accumulation in premelanosomes is dramatically reduced. Mature melanosomes in these cells are larger, rounder, more highly pigmented, and less striated than in control melanocytes. These data reveal a dual sorting defect in a natural mutant of Pmel17 and support a requirement of endocytic trafficking in Pmel17 fibril formation.
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Affiliation(s)
- Alexander C. Theos
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Joanne F. Berson
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Sarah C. Theos
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Kathryn E. Herman
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Dawn C. Harper
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Danièle Tenza
- Institut Curie, UMR-144, Centre National de la Recherche Scientifique, Paris, France 75005
| | - Elena V. Sviderskaya
- Division of Basic Medical Sciences, St. George’s, University of London, London SW17 0RE, United Kingdom; and
| | - M. Lynn Lamoreux
- Comparative Genetics Program, Texas A&M University, College Station, TX 77843
| | - Dorothy C. Bennett
- Division of Basic Medical Sciences, St. George’s, University of London, London SW17 0RE, United Kingdom; and
| | - Graça Raposo
- Institut Curie, UMR-144, Centre National de la Recherche Scientifique, Paris, France 75005
| | - Michael S. Marks
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
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96
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Ohno H. Physiological Roles of Clathrin Adaptor AP Complexes: Lessons from Mutant Animals. ACTA ACUST UNITED AC 2006; 139:943-8. [PMID: 16788044 DOI: 10.1093/jb/mvj120] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Clathrin-associated adaptor protein (AP) complexes play a key role in the transport of proteins, by regulating the formation of transport vesicles as well as cargo selection, between organelles of the post-Golgi network, namely, the trans-Golgi network (TGN), endosomes, lysosomes and the plasma membrane. Evidence has been accumulating for the physiological importance of AP complexes. Deficiency in AP-1A or AP-2 results in embryonic lethality in mice, indicating that these AP complexes are essential for normal development of embryos in mammals. In contrast, mutations in the genes encoding subunits of AP-3A cause an autosomal recessive disorder, Hermansky-Pudlak syndrome in human and its disease models in mice. Knockout mice for the neuron-specific AP-3B suffer from epileptic seizure. Further studies on the physiological and pathological aspects of AP complexes will not only be beneficial for better understanding of developmental biology and medical sciences, but also deepen our insight into the molecular mechanisms of vesicular traffic.
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Affiliation(s)
- Hiroshi Ohno
- Laboratory for Epithelial Immunobiology, Research Center for Allergy and Immunology (RCAI), RIKEN, Yokohama.
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97
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Gupta SN, Kloster MM, Rodionov DG, Bakke O. Re-routing of the invariant chain to the direct sorting pathway by introduction of an AP3-binding motif from LIMP II. Eur J Cell Biol 2006; 85:457-67. [PMID: 16542748 DOI: 10.1016/j.ejcb.2006.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 02/01/2006] [Accepted: 02/02/2006] [Indexed: 11/16/2022] Open
Abstract
AP3 is a heteromeric adaptor protein complex involved in the biogenesis of late endosomal/lysosomal structures. It recognizes tyrosine- and leucine-based sorting signals present in the cytoplasmic tails or loops of a number of proteins and is thought to be responsible for the direct transport of these proteins from the Golgi network to late endosomal/lysosomal structures. We have previously reported (Rodionov, Höning, Silye, Kongsvik, von Figura, Bakke, 2002. Structural requirements for interactions between leucine-sorting signals and clathrin-associated adaptor protein complex AP3. J. Biol. Chem. 277, 47436-47443) that in vitro binding of AP3 to the leucine signals is dependent on the nature of three residues immediately upstream of the leucine signal and suggested that these three amino acids define whether the protein is sorted to endosomes via the plasma membrane (PM) or traffics directly to the late endosomes/lysosomes. In this paper, we show in vivo evidence that residues favoring AP3 binding introduced into a protein that is transported via the PM such as the invariant chain can re-route such protein into direct sorting to late endosomal/lysosomal structures.
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Affiliation(s)
- Shailly N Gupta
- Department of Molecular Biosciences, University of Oslo, N-0316 Oslo, Norway
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98
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Valencia JC, Watabe H, Chi A, Rouzaud F, Chen KG, Vieira WD, Takahashi K, Yamaguchi Y, Berens W, Nagashima K, Shabanowitz J, Hunt DF, Appella E, Hearing VJ. Sorting of Pmel17 to melanosomes through the plasma membrane by AP1 and AP2: evidence for the polarized nature of melanocytes. J Cell Sci 2006; 119:1080-91. [PMID: 16492709 PMCID: PMC4629779 DOI: 10.1242/jcs.02804] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Adaptor proteins (AP) play important roles in the sorting of proteins from the trans-Golgi network, but how they function in the sorting of various melanosome-specific proteins such as Pmel17, an essential structural component of melanosomes, in melanocytes is unknown. We characterized the processing and trafficking of Pmel17 via adaptor protein complexes within melanocytic cells. Proteomics analysis detected Pmel17, AP1 and AP2, but not AP3 or AP4 in early melanosomes. Real-time PCR, immunolabeling and tissue in-situ hybridization confirmed the coexpression of AP1 isoforms mu1A and mu1B (expressed only in polarized cells) in melanocytes and keratinocytes, but expression of mu1B is missing in some melanoma cell lines. Transfection with AP1 isoforms (mu1A or mu1B) showed two distinct distribution patterns that involved Pmel17, and only mu1B was able to restore the sorting of Pmel17 to the plasma membrane in cells lacking mu1B expression. Finally, we established that expression of mu1B is regulated physiologically in melanocytes by UV radiation or DKK1. These results show that Pmel17 is sorted to melanosomes by various intracellular routes, directly or indirectly through the plasma membrane, and the presence of basolateral elements in melanocytes suggests their polarized nature.
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Affiliation(s)
- Julio C. Valencia
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hidenori Watabe
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - An Chi
- Chemistry Department, University of Virginia, Charlottesville, VA 22904-4319, USA
| | - Francois Rouzaud
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kevin G. Chen
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wilfred D. Vieira
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kaoruko Takahashi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yuji Yamaguchi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Werner Berens
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kunio Nagashima
- Image Analysis Laboratory, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Jeffrey Shabanowitz
- Chemistry Department, University of Virginia, Charlottesville, VA 22904-4319, USA
| | - Donald F. Hunt
- Chemistry Department, University of Virginia, Charlottesville, VA 22904-4319, USA
- Pathology Department, Health Sciences Center, University of Virginia, Charlottesville, VA 22908, USA
| | - Ettore Appella
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vincent J. Hearing
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Author for correspondence ()
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99
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Mitsunari T, Nakatsu F, Shioda N, Love PE, Grinberg A, Bonifacino JS, Ohno H. Clathrin adaptor AP-2 is essential for early embryonal development. Mol Cell Biol 2005; 25:9318-23. [PMID: 16227583 PMCID: PMC1265839 DOI: 10.1128/mcb.25.21.9318-9323.2005] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The heterotetrameric adaptor protein (AP) complexes AP-1, AP-2, AP-3, and AP-4 play key roles in transport vesicle formation and cargo sorting in post-Golgi trafficking pathways. Studies on cultured mammalian cells have shown that AP-2 mediates rapid endocytosis of a subset of plasma membrane receptors. To determine whether this function is essential in the context of a whole mammalian organism, we carried out targeted disruption of the gene encoding the mu2 subunit of AP-2 in the mouse. We found that mu2 heterozygous mutant mice were viable and had an apparently normal phenotype. In contrast, no mu2 homozygous mutant embryos were identified among blastocysts from intercrossed heterozygotes, indicating that mu2-deficient embryos die before day 3.5 postcoitus (E3.5). These results indicate that AP-2 is indispensable for early embryonic development, which might be due to its requirement for cell viability.
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Affiliation(s)
- Takashi Mitsunari
- Laboratory for Epithelial Immunobiology, Research Center for Allergy and Immunology, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
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100
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Stern LJ, Potolicchio I, Santambrogio L. MHC class II compartment subtypes: structure and function. Curr Opin Immunol 2005; 18:64-9. [PMID: 16337363 DOI: 10.1016/j.coi.2005.11.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Accepted: 11/24/2005] [Indexed: 11/24/2022]
Abstract
Reports from the past couple of years point to an emerging association of the biogenesis, composition and ultrastructural morphology of MHC class II compartments (MIICs) with their functions in antigen processing and loading. Growth factors and cytokines involved in dendritic cell maturation have been shown to regulate MIIC biogenesis, and the MHC-class-II-associated invariant chain chaperone has been reported to regulate endosomal morphology and vacuolation. Differences among ultrastructurally distinct MIICs have begun to be appreciated with regard to variation in antigen loading capacity and to polarization of MHC class II conformational variants among different compartments. Finally, the MIIC ultrastructure organizes the mechanism of MHC class II surface trafficking. Together, these findings begin to shed light on the connection between MIIC protein content, MIIC morphology and MHC class II-related antigen processing.
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Affiliation(s)
- Lawrence J Stern
- Department of Pathology University of Massachusetts Medical School Worcester, MA 01655, USA
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