Both vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8) play an important role in the progression of gastric cancer (GC). In this study, we investigated whether circulating levels of VEGF or IL-8 in drainage veins of GC patients were correlated with any clinicopathological factors. Thirty-seven patients with primary GC who underwent gastrectomy at our department between 1999 and 2002 were analyzed. Blood samples were drawn from a peripheral vein just before surgery and from a drainage vein immediately after laparotomy. Plasma VEGF levels were significantly higher than those in 10 healthy controls. There was no correlation between VEGF levels in drainage veins and any clinicopathological variable, whereas there was a significant relationship in the case of VEGF levels in peripheral veins; the levels were higher in patients with venous invasion. We found a significant relationship between IL-8 levels in drainage veins and both tumor size and lymph node metastasis, whereas no significant relationship between IL-8 levels in peripheral veins and any variable was found. There was no correlation between VEGF and IL-8 levels in drainage veins. Large tumors, deeply invasive tumors, lymph node involvement, venous invasion and high IL-8 levels in drainage veins were all significantly associated with shorter diseasefree survival, although multivariate analysis revealed that lymph node involvement was the only independent prognostic factor. In conclusion, the measurement of IL-8 levels in drainage veins of GC patients may reflect production mainly by the primary lesion and is valuable as an indicator of risk for recurrent disease.

LETM1 is a mitochondrial inner membrane protein that is required for maintaining the mitochondrial morphology and cristae structures, and regulates mitochondrial ion homeostasis. Here we report a role of LETM1 in the organization of cristae structures. We identified four amino acid residues of human LETM1 that are crucial for complementation of the growth deficiency caused by gene deletion of a yeast LETM1 orthologue. Substituting amino acid residues with alanine disrupts the correct assembly of a protein complex containing LETM1 and prevents changes in the mitochondrial morphology induced by exogenous LETM1 expression. Moreover, the LETM1 protein changes the shapes of the membranes of in vitroreconstituted proteoliposomes, leading to the formation of invaginated membrane structures on artificial liposomes. LETM1 mutant proteins with alanine substitutions fail to facilitate the formation of invaginated membrane structures, suggesting that LETM1 plays a fundamental role in the organization of mitochondrial membrane morphology.

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Paired Ig-like type 2 receptor α (PILRα) recognizes a wide range of O-glycosylated mucin and related proteins to regulate broad immune responses. However, the molecular characteristics of these recognitions are largely unknown. Here we show that sialylated O-linked sugar T antigen (sTn) and its attached peptide region are both required for ligand recognition by PILRα. Furthermore, we determined the crystal structures of PILRα and its complex with an sTn and its attached peptide region. The structures show that PILRα exhibits large conformational change to recognize simultaneously both the sTn O-glycan and the compact peptide structure constrained by proline residues. Binding and functional assays support this binding mode. These findings provide significant insight into the binding motif and molecular mechanism (which is distinct from sugar-recognition receptors) by which O-glycosylated mucin proteins with sTn modifications are recognized in the immune system as well as during viral entry.ucin-type O-glycosylation is highly important in physiological events, but it is too complicated to be fully understood because the structures of modified O-linked sugars are basically heterogeneous and are extremely difficult to predict. However, this complexity is beneficial in discriminating cellular conditions. To date, a number of molecules have been shown to recognize O-glycans, which are important in many biological events, including tumorigenesis and immune evasion (1), as well as infectious diseases. Selectins recognize the O-glycan parts of mucin-type glycoproteins on target cell surfaces to regulate the rolling and attachment of lymphocytes in inflammation and in cancer metastasis. However, how O-glycosylated proteins are recognized by specific receptors has remained largely unclear.To regulate function, the immune system has a fine-tuning mechanism using paired receptors families in which members show opposite (activating and inhibitory) signaling even though their cognate ligand recognitions are essentially similar. It is believed that activating members exhibit lower affinity to ligands than inhibitory members, possibly preventing undesired overactivation of immune responses (2-4) [e.g., killer cell Ig-like receptors, CD94/NKG2 heterodimers, leukocyte Ig-like receptors, and CD28/CTLA-4 (5)]. Paired Ig-like type 2 receptor (PILR) is a member of a paired receptor family comprising activating and inhibitory members designated "PILRβ" and "PILRα," respectively. PILRs have one Ig-like domain in the extracellular region, which is responsible for the ligand recognition. Our previous reports showed that PILRs recognize the O-glycosylated mucin proteins, mouse CD99 (6), and PILR-associating neural protein (PANP) (7). A recent study identified two O-glycosylated ligands for PILRs, neuronal differentiation and proliferation factor-1 (NPDC1) and collectin-12 (COLEC12), expanding the PILRrecognizing O-glycosylated ligand family (8). All PILR ligands are mucin or have mucin-like domains in which the heavy O-glycosylation occurs...

The killer cell lectin-like receptor G1, KLRG1, is a cell surface receptor expressed on subsets of natural killer (NK) cells and T cells. KLRG1 was recently found to recognize E-cadherin and thus inhibit immune responses by regulating the effector function and the developmental processes of NK and T cells. E-cadherin is expressed on epithelial cells and exhibits Ca 2؉ -dependent homophilic interactions that contribute to cell-cell junctions. However, the mechanism underlying the molecular recognition of KLRG1 by E-cadherin remains unclear. Here, we report structural, binding, and functional analyses of this interaction using multiple methods. Surface plasmon resonance demonstrated that KLRG1 binds the E-cadherin N-terminal domains 1 and 2 with low affinity (K d ϳ7-12 M), typical of cell-cell recognition receptors. NMR binding studies showed that only a limited N-terminal region of E-cadherin, comprising the homodimer interface, exhibited spectrum perturbation upon KLRG1 complex formation. It was confirmed by binding studies using a series of E-cadherin mutants. Furthermore, killing assays using KLRG1؉ NK cells and reporter cell assays demonstrated the functional significance of the N-terminal region of E-cadherin. These results suggest that KLRG1 recognizes the N-terminal homodimeric interface of domain 1 of E-cadherin and binds only the monomeric form of E-cadherin to inhibit the immune response. This raises the possibility that KLRG1 detects monomeric E-cadherin at exposed cell surfaces to control the activation threshold of NK and T cells.