The CTLA-4 pathway is a key regulator of T cell activation and a critical failsafe against autoimmunity. Although early models postulated that CTLA-4 transduced a negative signal, in vivo evidence suggests that CTLA-4 functions in a cell-extrinsic manner. That multiple cell-intrinsic mechanisms have been attributed to CTLA-4, yet its function in vivo appears to be cell-extrinsic, has been an on...

Terpinen-4-ol is a terpene found in the rhizome of Plai (Zingiber montanum (Koenig) Link ex Dietr.). In this study apoptogenic activity and mechanisms of cell death induced by terpinen-4-ol were investigated in the human leukemic MOLT-4 cell line. Terpinen-4-ol exhibited cytotoxicity in MOLT-4 cells, with characteristic morphological features of apoptosis by Wright's staining. The mode of cell ...

Meningococcal porin PorB is an inhibitor of apoptosis induced via the intrinsic pathway in various cell types. This effect is attributed to prevention of mitochondrial depolarization and of subsequent release of proapoptotic mitochondrial factors. To determine whether apoptosis is globally inhibited by PorB, we compared the intrinsic and extrinsic pathways in HeLa cells. Interestingly, PorB doe...

To gain greater insight into the nature of the bleeding tendency in hemophilia, we compared the spatial dynamics of clotting in platelet-free plasma from healthy donors and from patients with severe hemophilia A or B (factor VIII:C or IX:C<1%). Clotting was initiated via the intrinsic or extrinsic pathway in a thin layer of nonstirred plasma by bringing it in contact with the glass or fibroblas...

Apoptotic cell death of differentiated skeletal muscle has been reported in an experimental steroid-induced myopathy of rats. To investigate the underlying molecular changes in the apoptosis of skeletal muscle, in situ end labeling (ISEL), Fas expression, and Western blot analysis for apoptosis-related proteins in the soleus muscle of triamcinolone acetonide (TA)-induced myopathy of rats were s...

Fucoidan, a sulfated polysaccharide, has a variety of biological activities, such as anti-cancer, anti-angiogenic and anti-inflammatory. However, the mechanisms of action of fucoidan as an anti-cancer agent have not been fully elucidated. The present study examined the anti-cancer effect of fucoidan obtained from Undaria pinnatifida in PC-3 cells, human prostate cancer cells. Fucoidan induced t...

Apoptosis plays an important role in many developmental processes and contributes to cell and tissue homeostasis. Induction of apoptosis can involve the "intrinsic pathway", which is activated by diverse stress signals, and the "extrinsic pathway", which is activated by proapoptotic receptor signals at the cell surface. Excessive or aberrant apoptosis is a crucial factor in many human disorders...

Caspase-8 belongs to the family of cysteine proteases that plays a critical role in the regulation of programmed cell death (apoptosis). For example, caspase-8 function is required for proper signaling via the death receptor (extrinsic) pathway. Accordingly, the disturbance of caspase-8 expression or function may contribute to cancer formation and progression. In addition, inactivation of caspa...