Over-expression of stomatin causes syncytium formation in nonfusogenic JEG-3 choriocarcinoma placental cells.

Placental trophoblast differentiation involves the continuous fusion of mononuclear cytotrophoblasts. However, except for syncytin, little is known about the detailed mechanisms underlying trophoblast fusion. A previous study indicated that lipid rafts play an important role in HTLV-1 syncytium formation. To identify proteins that may be involved in placental trophoblast differentiation, we examined stomatin, an important lipid-raft protein that localizes to detergent-resistant membrane domains. The syncytium and human chorionic gonadotropin (ß-hCG; a marker of placental trophoblast differentiation) were visualized by immunofluorescence staining. We found that overexpression of stomatin in the nonfusogenic JEG-3 cell line caused syncytium formation and increased the fusion index of cells. Treating these cells with N(6) ,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate further increased cell fusion by stomatin. ß-hCG was found in a few JEG-3 cells overexpressing stomatin at 48 h, and its levels increased dramatically at 72 h along with the formation of the multinuclear syncytium. RNA interference was used to decrease stomatin expression in BeWo cells, a fusogenic human choriocarcinoma cell line. After knockdown for 72 h, stomatin levels decreased by almost 95%. The fusion indexes of control and stomatin-knockdown cells at 72 h were 9.4 and 6.5%, respectively. Our data indicated that stomatin could trigger syncytium formation and upregulate ß-hCG for cell fusion in nonfusogenic JEG-3 cells. Downregulation of stomatin slightly inhibited the fusion index of fusogenic BeWo cells. Thus, these data suggested that stomatin plays an important role in trophoblast differentiation.

Coronary Artery Bypass in Young Patients-On or Off-Pump?

A definitive conclusion regarding whether on-pump or off-pump coronary artery bypass is preferable in young patients is lacking. The aim of our study was to perform a long-term comparison of the two approaches in young patients. We analyzed the National Health Insurance Research Database, using data for patients between 18 and 45 years of age who had undergone isolated coronary artery bypass between 2001 and 2011. The study endpoints were: all-cause death, major adverse cardiac and cerebrovascular events, and repeat revascularization within 30 days, 1 year, 5 years, and the entire 10-year follow-up period. A total of 344 patients received off-pump surgery and 741 patients received on-pump surgery. Preoperative characteristics and comorbidities were similar in both groups, and all-cause mortality was almost equal (p = 0.716). The 5-year survival rates were 93.9% and 92.2% in the off-pump and on-pump groups, respectively, and the 10-year survival rates were 86.3% and 82.1%, respectively. The repeat revascularization rate was significantly lower in the on-pump group (p = 0.0407). Both the on-pump and off-pump methods offer equally good long-term outcomes in terms of mortality and major adverse cardiac and cerebrovascular events. However, the need for repeat revascularization is a concern in the long term after off-pump surgery.

NBT-II cell locomotion is modulated by restricting the size of focal contacts and is improved through EGF and ROCK signaling.

Focal contacts, large macromolecular complexes that link the extracellular matrix and the internal cell cytoskeleton, are thought to govern cell locomotion. However, the maturation process through which focal contacts control the cellular migratory machinery by changes in size and molecular composition remain unclear. Here, we fabricated cell growth substrates that contained linear ECM strips of micron- or submicron-width in order to limit the enlargement of focal contacts. We found that NBT-II cells plated on the submicron substrate possessed smaller focal complexes that exhibited a highly dynamic turnover. These cells possessed various leading edges at multiple sites of the cell periphery, which prevented the cell from advancing. In contrast, cells grown on the micron-width substrate possessed large and stable focal adhesions. Most of these cells were elongated bipolar cells that were tethered at both ends and were immobile. Further, EGF and ROCK signaling pathways can modulate the cellular migratory responses according to the substrate guidance. On the submicron-width substrate, EGF treatment increased the focal contact size and the contractile force, causing these cells to develop one leading edge and migrate along the submicron-sized ECM paths. In contrast, inhibition of ROCK signaling decreased the focal contact size for cells plated on the micron substrate. These cells became less tethered and were able to migrate along or even across the micron-sized ECM paths. Our results indicate that formation and maturation of focal contacts is controlled by both ECM cues and intracellular signaling and they play a central role in directed cell motion.