Osteosarcoma, one of primary bone tumor in children and young adults, has poor prognosis and drug resistances to chemotherapy. In order to reinforce the conventional therapies and antagonize the osteosarcoma in patients, a novel strategy is required for developing a new treatment. In this study, surfactin, a natural product from Bacillus subtilis, showed the efficiency of cell death in osteosarcoma, but not in normal cells. Surfactin triggers ER stress mechanism by promoting the aberrant Ca2+ release from ER lumen and ER‐signaling to mitochondrial dysfunction following caspases activation mediating cell apoptosis. Surfactin‐induced ER stress not only upregulated of glucose‐regulated protein 78/94 and IRE1‐ASK1‐JNK pathway but also leading to calpains and Bcl‐2 proteins family involving the release of cytochrome c. The releases into cytosol trigger the cleavage of caspase‐9 and caspase‐3 to induce cell apoptosis. In this study, surfactin demonstrated the potential functions to trigger the ER stress, ER stress‐associated IRE1‐ASK1‐JNK signaling pathway, mitochondrial dysfunction, and caspase activations leading to programmed cell apoptosis. Importantly, implicating the signaling pathway that regulates the connection between ER stress and mitochondrial dysfunction causing apoptosis associated with surfactin. These results indicated a potential application of surfactin strengthen current conventional therapies.
A Ramularia-like hyphomycete was discovered on uredinia of Phakopsora ampelopsidis on leaves of wild Ampelopsis brevipedunculata and cultivated Parthenocissus tricuspidata in several cities in Taiwan. The micromorphology of this fungicolous fungus is similar to that of species of the genus Ramularia which are mostly plant parasites but some species grow on rust fungi. Analyses of SSU and LSU rDNA and RPB2 gene sequence data and of ultrastructural features observed by scanning and transmission electron microscopy revealed that the fungus represents a novel lineage within the Ustilaginomycotina. The name Quasiramularia phakopsoricola is proposed for this new species in a new genus, a new family, and a new order. Sequence data obtained for ITS1, 5.8S, and ITS2 rDNA, however, did not match to any known fungal lineage. Bioinformatics analyses showed that these sequence data are extremely GC poor, but most probably do not represent a pseudogene. Extreme deviations of GC content can be observed in several lineages of Basidiomycota. Such variations affect the results of phylogenetic analyses and are an important source of artifacts.
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