scholarly journals Convergence of Non-clathrin- and Clathrin-derived Endosomes Involves Arf6 Inactivation and Changes in Phosphoinositides

2003 ◽  
Vol 14 (2) ◽  
pp. 417-431 ◽  
Author(s):  
Naava Naslavsky ◽  
Roberto Weigert ◽  
Julie G. Donaldson
Keyword(s):  
Major Histocompatibility Complex ◽  
Kinase Inhibitor ◽  
Interleukin 2 ◽  
Dependent Manner ◽  
Complex Class ◽  
Α Subunit ◽  
Recycling Endosomes ◽  
Histocompatibility Complex ◽  
Late Endosomes ◽  
Early Endosomes

The trafficking of two plasma membrane (PM) proteins that lack clathrin internalization sequences, major histocompatibility complex class I (MHCI), and interleukin 2 receptor α subunit (Tac) was compared with that of PM proteins internalized via clathrin. MHCI and Tac were internalized into endosomes that were distinct from those containing clathrin cargo. At later times, a fraction of these internalized membranes were observed in Arf6-associated, tubular recycling endosomes whereas another fraction acquired early endosomal autoantigen 1 (EEA1) before fusion with the “classical” early endosomes containing the clathrin-dependent cargo, LDL. After convergence, cargo molecules from both pathways eventually arrived, in a Rab7-dependent manner, at late endosomes and were degraded. Expression of a constitutively active mutant of Arf6, Q67L, caused MHCI and Tac to accumulate in enlarged PIP2-enriched vacuoles, devoid of EEA1 and inhibited their fusion with clathrin cargo-containing endosomes and hence blocked degradation. By contrast, trafficking and degradation of clathrin-cargo was not affected. A similar block in transport of MHCI and Tac was reversibly induced by a PI3-kinase inhibitor, implying that inactivation of Arf6 and acquisition of PI3P are required for convergence of endosomes arising from these two pathways.

scholarly journals The Dendritic Cell Receptor for Endocytosis, Dec-205, Can Recycle and Enhance Antigen Presentation via Major Histocompatibility Complex Class II–Positive Lysosomal Compartments

2000 ◽  
Vol 151 (3) ◽  
pp. 673-684 ◽  
Author(s):  
Karsten Mahnke ◽  
Ming Guo ◽  
Sena Lee ◽  
Homero Sepulveda ◽  
Suzy L. Swain ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Antigen Presentation ◽  
Class Ii ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Late Endosomes ◽  
Early Endosomes

Many receptors for endocytosis recycle into and out of cells through early endosomes. We now find in dendritic cells that the DEC-205 multilectin receptor targets late endosomes or lysosomes rich in major histocompatibility complex class II (MHC II) products, whereas the homologous macrophage mannose receptor (MMR), as expected, is found in more peripheral endosomes. To analyze this finding, the cytosolic tails of DEC-205 and MMR were fused to the external domain of the CD16 Fcγ receptor and studied in stable L cell transfectants. The two cytosolic domains each mediated rapid uptake of human immunoglobulin (Ig)G followed by recycling of intact CD16 to the cell surface. However, the DEC-205 tail recycled the CD16 through MHC II–positive late endosomal/lysosomal vacuoles and also mediated a 100-fold increase in antigen presentation. The mechanism of late endosomal targeting, which occurred in the absence of human IgG, involved two functional regions: a membrane-proximal region with a coated pit sequence for uptake, and a distal region with an EDE triad for the unusual deeper targeting. Therefore, the DEC-205 cytosolic domain mediates a new pathway of receptor-mediated endocytosis that entails efficient recycling through late endosomes and a greatly enhanced efficiency of antigen presentation to CD4+ T cells.

scholarly journals Relationship between invariant chain expression and major histocompatibility complex class II transport into early and late endocytic compartments.

1993 ◽  
Vol 177 (3) ◽  
pp. 583-596 ◽  
Author(s):  
P Romagnoli ◽  
C Layet ◽  
J Yewdell ◽  
O Bakke ◽  
R N Germain
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Endocytic Pathway ◽  
Invariant Chain ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Endocytic Compartments

Invariant chain (Ii), which associates with major histocompatibility complex (MHC) class II molecules in the endoplasmic reticulum, contains a targeting signal for transport to intracellular vesicles in the endocytic pathway. The characteristics of the target vesicles and the relationship between Ii structure and class II localization in distinct endosomal subcompartments have not been well defined. We demonstrate here that in transiently transfected COS cells expressing high levels of the p31 or p41 forms of Ii, uncleaved Ii is transported to and accumulates in transferrin-accessible (early) endosomes. Coexpressed MHC class II is also found in this same compartment. These early endosomes show altered morphology and a slower rate of content movement to later parts of the endocytic pathway. At more moderate levels of Ii expression, or after removal of a highly conserved region in the cytoplasmic tail of Ii, coexpressed class II molecules are found primarily in vesicles with the characteristics of late endosomes/prelysosomes. The Ii chains in these late endocytic vesicles have undergone proteolytic cleavage in the lumenal region postulated to control MHC class II peptide binding. These data indicate that the association of class II with Ii results in initial movement to early endosomes. At high levels of Ii expression, egress to later endocytic compartments is delayed and class II-Ii complexes accumulate together with endocytosed material. At lower levels of Ii expression, class II-Ii complexes are found primarily in late endosomes/prelysosomes. These data provide evidence that the route of class II transport to the site of antigen processing and loading involves movement through early endosomes to late endosomes/prelysosomes. Our results also reveal an unexpected ability of intact Ii to modify the structure and function of the early endosomal compartment, which may play a role in regulating this processing pathway.

Functional expression of a heterologous major histocompatibility complex class I gene in transgenic mice

1987 ◽  
Vol 7 (11) ◽  
pp. 4003-4009
Author(s):  
C Bieberich ◽  
T Yoshioka ◽  
K Tanaka ◽  
G Jay ◽  
G Scangos
Keyword(s):  
Major Histocompatibility Complex ◽  
Transgenic Mice ◽  
Major Histocompatibility Complex Class ◽  
Inbred Mice ◽  
Class I ◽  
Dependent Manner ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
I Gene

The regulated expression of major histocompatibility complex class I antigens is essential for assuring proper cellular immune responses. To study H-2 class I gene regulation, we have transferred a foreign class I gene to inbred mice and have previously shown that the heterologous class I gene was expressed in a tissue-dependent manner. In this report, we demonstrate that these mice expressed the transgenic class I molecule on the cell surface without any alteration in the level of endogenous H-2 class I antigens. Skin grafts from transgenic mice were rapidly rejected by mice of the background strain, indicating that the transgenic antigen was expressed in an immunologically functional form. As with endogenous H-2 class I genes, the class I transgene was inducible by interferon treatment and suppressible by human adenovirus 12 transformation. Linkage analysis indicated that the transgene was not closely linked to endogenous class I loci, suggesting that trans-regulation of class I genes can occur for class I genes located outside the major histocompatibility complex.

scholarly journals TAPBPR mediates peptide dissociation from MHC class I using a leucine lever

2018 ◽  
Author(s):  
F. Tudor Ilca ◽  
Andreas Neerincx ◽  
Clemens Hermann ◽  
Ana Marcu ◽  
Stefan Stevanovic ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Class I ◽  
Dependent Manner ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
Peptide Dissociation ◽  
Peptide Exchange

AbstractTapasin and TAPBPR are known to perform peptide editing on major histocompatibility complex class I (MHC I) molecules, however, the precise molecular mechanism(s) involved in this process remain largely enigmatic. Here, using immunopeptidomics in combination with novel cell-based assays that assess TAPBPR-mediate peptide exchange, we reveal a critical role for the K22-D35 loop of TAPBPR in mediating peptide exchange on MHC I. We identify a specific leucine within this loop that enables TAPBPR to facilitate peptide dissociation from MHC I. Moreover, we delineate the molecular features of the MHC I F pocket required for TAPBPR to promote peptide dissociation in a loop-dependent manner. These data reveal that chaperone-mediated peptide editing of MHC I can occur by different mechanisms dependent on the C-terminal residue that the MHC I accommodates in its F pocket and provide novel insights that may inform the therapeutic potential of TAPBPR manipulation to increase tumour immunogenicity.Impact StatementThis work demonstrates for the first time that the K22-D35 loop of TAPBPR is the essential region for mediating peptide exchange and peptide selection on major histocompatibility complex class I molecules.

scholarly journals Functional expression of a heterologous major histocompatibility complex class I gene in transgenic mice.

1987 ◽  
Vol 7 (11) ◽  
pp. 4003-4009 ◽  
Author(s):  
C Bieberich ◽  
T Yoshioka ◽  
K Tanaka ◽  
G Jay ◽  
G Scangos
Keyword(s):  
Major Histocompatibility Complex ◽  
Transgenic Mice ◽  
Major Histocompatibility Complex Class ◽  
Inbred Mice ◽  
Class I ◽  
Dependent Manner ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
I Gene

The regulated expression of major histocompatibility complex class I antigens is essential for assuring proper cellular immune responses. To study H-2 class I gene regulation, we have transferred a foreign class I gene to inbred mice and have previously shown that the heterologous class I gene was expressed in a tissue-dependent manner. In this report, we demonstrate that these mice expressed the transgenic class I molecule on the cell surface without any alteration in the level of endogenous H-2 class I antigens. Skin grafts from transgenic mice were rapidly rejected by mice of the background strain, indicating that the transgenic antigen was expressed in an immunologically functional form. As with endogenous H-2 class I genes, the class I transgene was inducible by interferon treatment and suppressible by human adenovirus 12 transformation. Linkage analysis indicated that the transgene was not closely linked to endogenous class I loci, suggesting that trans-regulation of class I genes can occur for class I genes located outside the major histocompatibility complex.

scholarly journals Separation of subcellular compartments containing distinct functional forms of MHC class II.

1994 ◽  
Vol 125 (3) ◽  
pp. 595-605 ◽  
Author(s):  
Y Qiu ◽  
X Xu ◽  
A Wandinger-Ness ◽  
D P Dalke ◽  
S K Pierce
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Antigen Processing ◽  
Class Ii ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Subcellular Compartments ◽  
Early Endosomes ◽  
Dense Vesicles

Antigen processing in B lymphocytes entails initial binding of antigen to the surface Ig and internalization of the antigen into acidic compartments where the antigen is degraded, releasing peptides for binding to major histocompatibility complex class II molecules. Using subcellular fractionation techniques we show that functional, processed antigen-class II complexes capable of activating antigen-specific T cells in vitro are first formed in dense vesicles cosedimenting with lysosomes which are distinct from early endosomes and the bulk of late endosomes. With time, processed antigen-class II complexes appear in vesicles sedimenting with early endosomes and finally cofractionate with plasma membrane. A separate compartment is identified which contains major histocompatibility complex class II receptive to peptide binding but which does not have access to processed antigen in the B cell. These class II molecules are in the so-called "floppy" form in contrast to the class II molecules in the very dense vesicles which are in the "compact" form. These results demonstrate a correlation between the floppy and compact forms of class II molecules and their association with processed antigen and show that floppy and compact forms of class II reside in distinct and physically separable subcellular compartments.

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