A major reserve of MHC-I in dendritic cells reside within the endocytic recycling compartments (ERC). MHC-I trafficking to the ERC is regulated by the activity of Rab11a and subsequent trafficking from ERC to phagosomes is controlled by TLR-MyD88-IKK2-dependent phosphorylation of phagosomal SNAP23. Toll-like receptor (TLR) signalling regulate cross-presentation as they regulate phagocytosis and phagolysosomal fusion (Nair et al. 2011). MHC-I bearing ERC are enriched with R-SNAREs like RAB11a, VAMP3, and VAMP8. These SNARE molecules can interact with Q-SNARE SNAP23 present on phagosomes and this mediates membrane fusion. This interaction of SNAP23 with R-SNAREs require phosphorylation of SNAP23 (on Ser-95) by IKK2, and IKK2 is activated by TLR signalling. SNAP23 phosphorylation may increase SNAP23 binding to SNAREs. It may also regulate platelet and mast cell secretion (Karim et al. 2013, Suziki & Verma 2008).
Tampé, R, Whiteheart, SW, Florey, O, Blander, JM, Huang, Y, Baccarini, A, Amsen, D, Overholtzer, M, Brown, BD, Seyffer, F, Tung, N, Nair-Gupta, P, Roche, PA, Banerjee, M
Verma, IM, Suzuki, K
Karim, ZA, Zhang, J, Al Hawas, R, Whiteheart, SW, Chicka, MC, Roche, PA, Hamilton, TR, Banerjee, M
protein serine/threonine kinase activity of CHUK:IKBKB:IKBKG [cytosol]
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