SLAMF1 expression is usually induced by stimulation with either LPS or IL-1 and in phagocytes during active colitis (34, 55, 56)

SLAMF1 expression is usually induced by stimulation with either LPS or IL-1 and in phagocytes during active colitis (34, 55, 56). of SLAMF1 and SLAMF6 with outer membrane porins C (OmpC) and OmpF was demonstrated inside a cell-based luciferase reporter assay (11). The specificity LY 303511 of these interactions extends to different Gram? bacteria, but not Gram+ bacteria; SLAMF1 interacts with (11); SLAMF6 interacts with and to some degree with (38). Subsequent analyses shown that this connection depends on the IgV website of SLAMF1 and SLAMF6. The structure of SLAMF1 offers proven hard to unravel due to the flexible (non-rigid) nature and high degree of glycosylation of SLAMF1. By a combination of techniques, several amino acid residues have been implicated in SLAMF1 homophilic engagement as well as SLAMF1 engagement with Measles computer virus protein MV-H (10). The FCC beta-sheet and the CC loop of SLAMF1 consist of several conserved residues and substitution of Val63, Thr65, Ala67, Lys77, and Glu123 within these areas all resulted in a reduction in the binding of SLAMF1 to SLAMF1 as well as to MV-H. Solitary mutations of LY 303511 comparative residues in mouse SLAMF1 resulted in little difference in the binding of OmpC/F comprising structures does not require amino acid residues in the SLAMF6 IgV website that are crucial for SLAMF6CSLAMF6 homophilic ligation (38). However, general masking of connection domains by mAbs directed against epitopes in the IgV domains of SLAMF1 or SLAMF6 clogged their relationships with bacteria (11, 38). Therefore, whereas there is overlap in the SLAMF1 residues that are LY 303511 essential for SLAMF1CSLAMF1 ligation with the residues involved in MV-H binding to SLAMF1, it is likely that OmpC/F binding entails a separate set Mouse monoclonal to KSHV ORF45 of interacting SLAMF1 residues. This would suggest that the connection of SLAMF1 with bacteria is of a separate origin, distinct from your SLAMF1CSLAMF1 connection website, and hence may represent a SLAMF1 function of independent evolutionary significance. Structural analyses of SLAMF1 or SLAMF6 and outer membrane porins should provide conclusive insights into the mode of these relationships. SLAMF1 Enhances Phagocyte Effector Functions The connection of SLAMF1 with OmpC/F+ results in a more effective phagocytosis of these bacteria by macrophages (11). Clusters of SLAMF1 bound to OmpC/F remain proximal to the bacterium during phagocytosis, therefore colocalizing to intracellular phagosomes. A signaling complex is recruited to the intracellular website of SLAMF1 either directly upon bacterial ligation or soon thereafter during internalization. The transient recruitment of the autophagy scaffold protein Beclin-1 is the initial event that leads to the formation of a functional complex that also contains Vps34, Vps15, and UVRAG (Number ?(Number4)4) (13). This novel SLAMF1 signaling module is enhanced by, but not prerequisite of the presence of EAT-2 (13). Vps34 supported by its co-enzyme Vps15 is the only Class III phosphatidylinositol kinase and generates the docking lipid phosphatidylinositol-3-phosphate (PI3P) (39). This SLAMF1-enhanced production of PI3P affects two important phagosomal processes. First, formation and activation of the classical phagocytic NADPH oxidase (Nox2) complex is a tightly regulated process that involves assembly of the membrane certain catalytic gp91phox and p22phox with at least four cytosolic subunits p40phox, p47phox, p67phox, Rac1/2 (40). By recruiting the p40phox subunit to the maturing phagosome, PI3P initiates the formation of this superoxide-producing complex (39). Second, PI3P enables the recruitment of the tethering molecule EEA1, which is definitely critically involved in phagolysosomal fusion. Therefore, in the absence of SLAMF1 from phagocytes, the phagocytic process of specific Gram? bacteria is compromised. Open in a separate window Number 4 Slamf1 affects phagosome functions in two ways, after binding to can be bound by SLAMF1. Subsequently, SLAMF1 is definitely internalized into the progressing phagosome. The Vps34/15? ?UVRAG? ?Beclin-1 complex is formed. PI is converted to PI3P, which is the docking lipid for subunits of the Nox2 complex as well as the tethering molecule EEA-1. The result of the docking of these proteins is the progression of phagosomes toward bactericidal phagolysosomes that are able to destroy the internalized bacteria. The positive modulation of Nox2 complex formation by PKC-delta is definitely inhibited by SLAMF8. There is preliminary evidence for an inhibition by SLAMF8 of Vps34/15? ?UVRAG? ?Beclin-1 complex recruitment to SLAMF1. SLAMF2 Relationships with Gram? Bacteria SLAMF2 is definitely implicated in the acknowledgement of non-opsonized via surface type-1 fimbriae, which contain the lectin FimH (12). Microscopy and genetic analysis suggest that SLAMF2 binds to FimH, which is dependent on the presence of mannose on SLAMF2 (41). Uptake of FimH? is not mediated by SLAMF2 (42). SLAMF2 internalizes with FimH upon phagocytosis of FimH+ by mast cells and macrophages, which can be inhibited by mAb directed against SLAMF2. The force catch.