It is thought that inositol-1,4,5-trisphosphate (Ins(1,4,5)P(3))-Ca(2+) signalling has a function in dorsoventral axis formation in Xenopus embryos; however, the immediate target of free Ca(2+) is unclear. The secreted Wnt protein family comprises two functional groups, the canonical Wnt and Wnt/Ca(2+) pathways. The Wnt/Ca(2+) pathway interferes with the canonical Wnt pathway, but the underlying molecular mechanism is poorly understood. Here, we cloned the complementary DNA coding for the Xenopus homologue of nuclear factor of activated T cells (XNF-AT). A gain-of-function, calcineurin-independent active XNF-AT mutation (CA XNF-AT) inhibited anterior development of the primary axis, as well as Xwnt-8-induced ectopic dorsal axis development in embryos. A loss-of-function, dominant negative XNF-AT mutation (DN XNF-AT) induced ectopic dorsal axis formation and expression of the canonical Wnt signalling target molecules siamois and Xnr3 (ref. 4). Xwnt-5A induced translocation of XNF-AT from the cytosol to the nucleus. These data indicate that XNF-AT functions as a downstream target of the Wnt/Ca(2+) and Ins(1,4,5)P(3)-Ca(2+) pathways, and has an essential role in mediating ventral signals in the Xenopus embryo through suppression of the canonical Wnt pathway.

The anti-phospholipid syndrome (APS) is characterized by thrombosis and the presence of anti-phospholipid antibodies (aPL). Tissue factor (TF), the major initiator of the coagulation system, is induced on monocytes by aPL in vitro, explaining, in part, the pathophysiology in this syndrome. However, little is known regarding the nature of the aPL-induced signal transduction pathways leading to TF expression. In this study, we investigated aPL-inducible genes in PBMC using cDNA array system and real-time PCR. Our results indicated that the mitogen-activated protein kinase (MAPK) pathway was related to TF expression when PBMCs were treated, in the presence of beta(2)Glycoprotein I (beta(2)GPI), with human monoclonal anti-beta(2)GPI antibodies [beta(2)GPI-dependent anti-cardiolipin antibodies (aCL/beta(2)GPI)]. Western blotting studies using monocyte cell line (RAW264.7) demonstrated that p38 MAPK protein was phosphorylated with nuclear factor kappaB (NF-kappaB) activation by monoclonal aCL/beta(2)GPI treatment, and that SB203580, a specific p38 MAPK inhibitor, decreased the aCL/beta(2)GPI-induced TF mRNA expression. The p38 MAPK phosphorylation, NF-kappaB translocation and TF mRNA expression triggered by aCL/beta(2)GPI were abolished in the absence of beta(2)GPI. These results demonstrated that the p38 MAPK signaling pathway plays an important role in aPL-induced TF expression on monocytes and suggest that the p38 MAPK may be a possible therapeutic target to modify a pro-thrombotic state in patients with APS.

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SUMMARYThere are two major forms of the Fas molecule, membranous Fas and soluble Fas (sFas). To clarify the clinical significance of sFas in autoimmune diseases, we designed a sandwich ELISA to determine serum concentrations of sFas and its molecular structure, and we then analysed the correlation between levels of sFas and laboratory findings in patients with SLE and other autoimmune diseases. The levels of serum sFas were significantly higher in SLE patients than in subjects with other autoimmune diseases and in healthy donors, and the frequency of a positive serum sFas was much greater in SLE patients with high SLE disease activity index scores than in those with low scores. In addition, sFas-positive SLE patients showed a significant difference in various laboratory parameters from sFas-negative SLE patients. Serial measurements of serum sFas levels in SLE patients with active disease revealed that the elevated level of sFas dramatically decreased with improvement in clinical and laboratory findings, following corticosteroid therapy. We propose that the serum level of sFas can serve as an appropriate marker for evaluating SLE disease activity. Serum sFas is heterogeneous with respect to molecular structure, thus several mechanisms are involved in the generation of sFas.

␤ 2 -Glycoprotein I (␤ 2 -GPI) is proteolytically cleaved by plasmin in domain V (nicked ␤ 2 -GPI), being unable to bind to phospholipids. This cleavage may occur in vivo and elevated plasma levels of nicked ␤ 2 -GPI were detected in patients with massive plasmin generation and fibrinolysis turnover. In this study, we report higher prevalence of elevated ratio of nicked ␤ 2 -GPI against total ␤ 2 -GPI in patients with ischemic stroke (63%) and healthy subjects with lacunar infarct (27%) when compared to healthy subjects with normal findings on magnetic resonance imaging (8%), suggesting that nicked ␤ 2 -GPI might have a physiologic role beyond that of its parent molecule in patients with thrombosis. Several inhibitors of extrinsic fibrinolysis are known, but a negative feedback regulator has not been yet documented. We demonstrate that nicked ␤ 2 -GPI binds to Glu-plasminogen with K D of 0.37 ؋ 10 ؊6 M, presumably mediated by the interaction between the fifth domain of nicked ␤ 2 -GPI and the fifth kringle domain of Glu-plasminogen. Nicked ␤ 2 -GPI also suppressed plasmin generation up to 70% in the presence of tissue plasminogen activator, plasminogen, and fibrin. Intact ␤ 2 -GPI lacks these properties. These data suggest that ␤ 2 -GPI/plasmin-nicked ␤ 2 -GPI controls extrinsic fibrinolysis via a negative feedback pathway loop. Introduction␤ 2 -Glycoprotein I (␤ 2 -GPI), also known as apolipoprotein H, is a phospholipid-binding plasma protein. Phospholipid-bound ␤ 2 -GPI is one of the major target antigens for antiphospholipid antibodies 1-3 present in patients with antiphospholipid syndrome (APS), an autoimmune disorder characterized by arterial/venous thrombosis and pregnancy morbidity. 4 ␤ 2 -GPI has 5 homologous short consensus repeats, designated as domains I to V. Domains of ␤ 2 -GPI structurally resemble each other, except that domain V has an extra C-terminal loop and a positively charged lysine cluster. In 1993, Hunt et al 5 reported that ␤ 2 -GPI is proteolytically cleaved between Lys317 and Thr318 in domain V (nicked ␤ 2 -GPI), being unable to bind to phospholipids. This cleavage is generated by factor Xa or by plasmin, with plasmin being more effective. 6 A large number of reports have detailed the in vitro properties of ␤ 2 -GPI as a natural anticoagulant/procoagulant regulator by inhibiting phospholipid-dependent reactions, such as prothrombinase and tenase activity on platelets or phospholipid vesicles, 7,8 factor XII activation, 9 and anticoagulant activity of activated protein C. 10,11 Apart from specific hemostatic functions, ␤ 2 -GPI activates lipoprotein lipase, 12 lowers the triglyceride level, 13 binds to oxidized low-density lipoprotein to prevent the progression of atherosclerosis, 14 and binds to nonself particles or apoptotic bodies to allow their clearance. [15][16][17] Little attention has been given to the functions of the nicked form of ␤ 2 -GPI because its phospholipidbinding activity was thought to exert the physiologic or pathologic functions of ␤ 2 -GPI.Fibrinolytic reactions ...