Antigen-B Cell Receptor Complexes Associate with Intracellular major histocompatibility complex (MHC) Class II Molecules

Barroso, Margarida; Tucker, Heidi R.; Drake, Lisa A.; Nichol, Kathleen; Drake, James R.

doi:10.1074/jbc.m115.649582

Cited by 36 publications

(41 citation statements)

References 29 publications

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“…More recently, we extended the initial structural studies of King and Dixon (King and Dixon, 2010) and identified two I-A k class II conformers that differ in pairing of transmembrane (TM) domain GxxxG dimerization motifs [Figure 1, (Dixon et al, 2014)]. Moreover, we have demonstrated that while M1 paired class II molecules numerically represent ~10% of cell surface class II, they can carry greater than 90% of MHC class II function (Barroso et al, 2015; Busman-Sahay et al, 2011; Sprent et al, 1981). We have also established that M1 paired class II are enriched in plasma membrane lipid rafts (Busman-Sahay et al, 2011), have unique signaling properties (Nashar and Drake, 2006) and are selectively incorporated into a putative MHC class II peptide loading complex where cognate antigen bound to the BCR is converted into peptide bound to M1 paired class II (Barroso et al, 2015).…”

Section: Introductionmentioning

confidence: 63%

“…The plasmids were transfected into CIITA expressing 293T cells as previously reported (Busman-Sahay et al, 2011; Dixon et al, 2014). 24-48 hour culture supernatants were collected, cleared of debris by centrifugation and then analyzed by immunoprecipitation with either the 10-3.6 or 11-5.2 mAb and western blot with a rabbit antibody specific for a peptide derived from the Aβk extracellular domain (Barroso et al, 2015). …”

Section: Methodsmentioning

confidence: 99%

“…Equal amounts of pre-cleared samples were then immunoprecipitated with 5 μg of mAb (either 11-5.2 or 10-3.6) and 100 μl of 10% protein G-Sepharose. IPs were analyzed by streptavidin-HRP or anti-class II β chain blotting as previously reported (Barroso et al, 2015). The proteases used were: Proteinase K (Sigma, Cat # P6556, Trypsin (Sigma, Cat # T7409) and Chymotrypsin (Sigma, Cat # CHY5S).…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, we have demonstrated that while M1 paired class II molecules numerically represent ~10% of cell surface class II, they can carry greater than 90% of MHC class II function (Barroso et al, 2015; Busman-Sahay et al, 2011; Sprent et al, 1981). We have also established that M1 paired class II are enriched in plasma membrane lipid rafts (Busman-Sahay et al, 2011), have unique signaling properties (Nashar and Drake, 2006) and are selectively incorporated into a putative MHC class II peptide loading complex where cognate antigen bound to the BCR is converted into peptide bound to M1 paired class II (Barroso et al, 2015). Hence, M1 paired MHC class II molecules represent an important class II conformer with significant immunological functions.…”

Section: Introductionmentioning

confidence: 94%

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A triad of molecular regions contribute to the formation of two distinct MHC class II conformers

Drake

2016

Molecular Immunology

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MHC class II molecules present antigen-derived peptides to CD4 T cells to drive the adaptive immune response. Previous work has established that class II αβ dimers can adopt two distinct conformations, driven by the differential pairing of transmembrane domain GxxxG dimerization motifs. These class II conformers differ in their ability to be loaded with antigen-derived peptide and to effectively engage CD4 T cells. Motif 1 (M1) paired I-Ak class II molecules are efficiently loaded with peptides derived from the processing of B cell receptor-bound antigen, have unique B cell signaling properties and high T cell stimulation activity. The 11-5.2 mAb selectively binds M1 paired I-Ak class II molecules. However, the molecular determinants of 11-5.2 binding are currently unclear. Here, we report the ability of a human class II transmembrane domain to drive both M1 and M2 class II conformer formation. Protease sensitivity analysis further strengthens the idea that there are conformational differences between the extracellular domains of M1 and M2 paired class II. Finally, MHC class II chain alignments and site directed mutagenesis reveals a triad of molecular regions that contributes to 11-5.2 mAb binding. In addition to transmembrane GxxxG motif domain pairing, 11-5.2 binding is influenced directly by α chain residue Glu-71 and indirectly by the region around the inter-chain salt bridge formed by α chain Arg-52 and β chain Glu-86. These findings provide insight into the complexity of 11-5.2 mAb recognition of the M1 paired I-Ak class II conformer and further highlight the molecular heterogeneity of peptide-MHC class II complexes that drive T cell antigen recognition.

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Section: Introductionmentioning

confidence: 63%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

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A triad of molecular regions contribute to the formation of two distinct MHC class II conformers

Drake

2016

Molecular Immunology

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“…Interaction of internalized BCR/antigen with intracellular MHCII was observed in pulldowns using biotin-labeled antigen (78). Strikingly, a rare (10%) conformation of MHCII seems to be a predominant conformer in complex with the BCR/antigen.…”

Section: Internalization Of Bcr and Intersection With Mhcii In The Mhmentioning

confidence: 99%

The Other Function: Class II-Restricted Antigen Presentation by B Cells

et al. 2017

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Mature B lymphocytes (B cells) recognize antigens using their B cell receptor (BCR) and are activated to become antibody-producing cells. In addition, and integral to the development of a high-affinity antibodies, B cells utilize the specialized major histocompatibility complex class II (MHCII) antigen presentation pathway to process BCR-bound and internalized protein antigens and present selected peptides in complex with MHCII to CD4+ T cells. This interaction influences the fate of both types of lymphocytes and shapes immune outcomes. Specific, effective, and optimally timed antigen presentation by B cells requires well-controlled intracellular machinery, often regulated by the combined effects of several molecular events. Here, we delineate and summarize these events in four steps along the antigen presentation pathway: (1) antigen capture and uptake by B cells; (2) intersection of internalized antigen/BCRs complexes with MHCII in peptide-loading compartments; (3) generation and regulation of MHCII/peptide complexes; and (4) exocytic transport for presentation of MHCII/peptide complexes at the surface of B cells. Finally, we discuss modulation of the MHCII presentation pathway across B cell development and maturation to effector cells, with an emphasis on the shaping of the MHCII/peptide repertoire by two key antigen presentation regulators in B cells: HLA-DM and HLA-DO.

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Lysosomes and lysosome‐related organelles in immune responses

Watts

2022

FEBS Open Bio

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The catabolic, degradative capacity of the endo‐lysosome system is put to good use in mammalian immune responses as is their recently established status as signaling platforms. From the ‘creative destruction’ of antigenic and ‘self’ material for antigen presentation to T cells to the re‐purposing of lysosomes as toxic exocytosable lysosome‐related organelles (granules) in leukocytes such as CD8 T cells and eosinophils, endo‐lysosomes are key players in host defense. Signaled responses to some pathogen products initiate in endo‐lysosomes and these organelles are emerging as important in distinct ways in the unique immunobiology of dendritic cells. Potential self‐inflicted toxicity from lysosomal and granule proteases is countered by expression of serpin and cystatin family members.

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Antigen-B Cell Receptor Complexes Associate with Intracellular major histocompatibility complex (MHC) Class II Molecules

Cited by 36 publications

References 29 publications

A triad of molecular regions contribute to the formation of two distinct MHC class II conformers

A triad of molecular regions contribute to the formation of two distinct MHC class II conformers

The Other Function: Class II-Restricted Antigen Presentation by B Cells

Lysosomes and lysosome‐related organelles in immune responses

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