dendritic cells regulate exposure of mhc class ii at their plasma membrane by oligoubiquitination

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Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination Joost Snijder Vera Verhage Supervisor: Prof. W. Stoorvogel

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Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination. Joost Snijder Vera Verhage Supervisor: Prof. W. Stoorvogel. Proteolytic processing of MHC-II. Research Aim. To establish what role ubiquitination has in sorting of MHC-II complexes in DC’s. - PowerPoint PPT Presentation

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Page 1: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by

Oligoubiquitination

Joost SnijderVera Verhage

Supervisor: Prof. W. Stoorvogel

Page 2: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Proteolytic processing of MHC-II

Page 3: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Research Aim

To establish what role ubiquitination has in sorting of MHC-II complexes in DC’s

Page 4: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

MHCII-ß is oligo-ubiquitinated

Page 5: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Ubiquitination takes place in the MVB after peptide loading

Page 6: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Proteolytic processing of Ii is required for Ubiquitination, DC maturation interferes

Page 7: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Summary

• MHCII-ß is oligo-ubiquitinated

• Ubiquitination takes place in the MVB after peptide loading

• Proteolytic processing of Ii is required for ubiquitination

• LPS-induced maturation interferes with ubiquitination

Page 8: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Target residue 225

• Conserved Lysine residue 225• Ak-βK225A = mutant Lysine Alanine• 2 MHCII Haplotypes– Ab-α/β = Wild type– Ak-α/β = Transduced haplotype

Page 12: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Fig 5

• Endogenous MHC II in MVB was associated 74% with LV (74%)

• In Ak-bK225A, 16% was found located in LV– Sorting is drastically changed

Page 13: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Sorting steps

• Where is ubiquitination involved or required?– Is it endocytosis or

recycling?

Page 14: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Fig 6A

• Transfer from EEA1 to DM positive structure– EEA1, early endosomal marker– DM class II compartment

• Delay in Mutant Ak-bK225A

• 20°C, endocytosis occurs,but no recycling and transport to lysosomes

Page 15: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

• Less Ak-bK225A was detected intracellularly (vs Ab-b) (ratio 5.5 ± 1.4)

• Due to reduced uptake or accelerated recyling?

Page 16: Dendritic Cells Regulate Exposure of MHC Class II at Their Plasma Membrane by Oligoubiquitination

Conclusion

• Ubiquitination of MHC II-b – occurs at lysine 225 and is required for

intracellular retention of MHC II in immature DCs.– is required for sorting at MVB, failure result in

transfer by default to the plasma membrane– Is required for efficient endocytosis