ABSTRACT
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains one of the most important infectious diseases worldwide. Mtb and its culture filtrates or sonic extracts induce apoptosis in macrophages. However, there is a little known about Mtb components that modulate apoptosis and their regulating mechanism. We identified Rv0753c protein with apoptotic potential through searching the biologic active proteins from the multidimensional fractions of Mtb culture filtrate. Here, we investigated the apoptotic effects of Rv0753c on RAW264.7 cells. The recombinant Rv0753c induced RAW264.7 cells apoptosis in a caspase-9-dependent manner. Dissipation of the mitochondrial transmembrane potential (ΔΨ m ), mitochondrial translocation of Bax, and release of cytochrome c from mitochondria were observed in macrophages treated with Rv0753c. Enhanced reactive oxygen species (ROS) production was required for Rv0753c-mediated apoptosis. Furthermore, ROS-mediated JNK activation was major signaling pathway for Rv0753c-induced apoptosis. Moreover, Rv0753c-mediated apoptosis is dependent on TLR4. Altogether, these results suggest that Rv0753c induce apoptosis through ROS-JNK signaling pathway in RAW264.7 cells.
ABSTRACT
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains one of the most important infectious diseases worldwide. Mtb and its culture filtrates or sonic extracts induce apoptosis in macrophages. However, there is a little known about Mtb components that modulate apoptosis and their regulating mechanism. We identified Rv0753c protein with apoptotic potential through searching the biologic active proteins from the multidimensional fractions of Mtb culture filtrate. Here, we investigated the apoptotic effects of Rv0753c on RAW264.7 cells. The recombinant Rv0753c induced RAW264.7 cells apoptosis in a caspase-9-dependent manner. Dissipation of the mitochondrial transmembrane potential (ΔΨ m ), mitochondrial translocation of Bax, and release of cytochrome c from mitochondria were observed in macrophages treated with Rv0753c. Enhanced reactive oxygen species (ROS) production was required for Rv0753c-mediated apoptosis. Furthermore, ROS-mediated JNK activation was major signaling pathway for Rv0753c-induced apoptosis. Moreover, Rv0753c-mediated apoptosis is dependent on TLR4. Altogether, these results suggest that Rv0753c induce apoptosis through ROS-JNK signaling pathway in RAW264.7 cells.
ABSTRACT
To examine the electrophysiological properties of luteal cells and the relationship between membrane potential and luteal steroidogenic capacity, the membrane potential of luteal cells and the luteal steroidogenesis were measured under different ionic conditions following treatment with various drugs and gonadotropins. The membrane potential of luteal cells did not vary throughout the estrous cycle and was -55 +/- 1 mV. The membrane potential was highly dependent upon the external K+ concentration and was depolarized by the deprivation of external Ca2+, however) there seemed to be a lower K+ permeability in luteal membranes as the presence of 10-9 M valinomycin, a K+ ionophore Caused hyperpolarization from -55 to -91 mV. Luteal progestin production was increased in a high K+ solution but not m a Ca2+-free solution indicating that Ca2+ may be essential for steroid synthesis and/or secretion by luteal cells. Gonadotropins and ouabain induced a depolarization of the membrane potential and stimulated luteal steroidogenesis; however; prostaglandin F2alpha stimulated only steroidogenesis without any changes in membrane potential. These results suggest that the relationship between steroidogenesis and the changes in membrane potential by drugs and gonadotropins is still obscure and remains to be eluridated. The relationship between membrane potential and steroidogenesis in the luteal cell may be dependent upon the availability of intracelluar Ca2+.