Vesicular stomatitis virus infection triggers apoptosis associated with decreased DeltaNp63alpha and increased Bax levels in the immortalized HaCaT keratinocyte cell line

Elevation of Cleaved p18 Bax Levels Associated with the Kinetics of Neuronal Cell Death during Japanese Encephalitis Virus Infection

Japanese encephalitis virus (JEV) infection induces uncontrolled neuronal apoptosis, leading to irreversible brain damage. However, the mechanism of JEV-induced neuronal apoptosis has not been clearly elucidated. This study aimed to investigate both virus replication and neuronal cell apoptosis during JEV infection in human neuroblastoma SH-SY5Y cells. As a result, the kinetic productions of new viral progeny were time- and dose-dependent. The stimulation of SH-SY5Y cell apoptosis was dependent on the multiplicity of infections (MOIs) and infection periods, particularly during the late period of infection. Interestingly, we observed that of full-length Bax (p21 Bax) level started to decrease, which corresponded to the increased level of its cleaved form (p18 Bax). The formation of p18 Bax resulting in cytochrome c release into the cytosol appeared to correlate with JEV-induced apoptotic cell death together with the activation of caspase-3/7 activity, especially during the late stage of a robust viral infection. Therefore, our results suggest another possible mechanism of JEV-induced apoptotic cell death via the induction of the proteolysis of endogenous p21 Bax to generate p18 Bax. This finding could be a new avenue to facilitate novel drug discovery for the further development of therapeutic treatments that could relieve neuronal damage from JEV infection.

c-Abl contributes to glucose-promoted apoptosis via p53 signaling pathway in podocytes

AIM

To investigate the role of the non-receptor tyrosine kinase c-Abl in high glucose-induced podocyte injury and its possible signal transduction pathway.

METHODS

Sixteen C57BL/6 mice were randomly assigned to a group with diabetes and a normal control group. Subsequently, differentiated mouse podocytes were exposed to high-glucose conditions, and podocyte apoptosis was then assessed by flow cytometry and Hoechst 33258 staining. Western blot and immunofluorescence assay were used to measure c-Abl expression. Co-immunoprecipitation assay was used and c-Abl siRNA was applied to evaluate the interaction between c-Abl and p53.

RESULTS

High glucose promotes podocyte apoptosis. The c-Abl expression in podocytes was increased after exposure to high glucose, stimulating the p53 signaling pathway. Conversely, treatment with c-Abl siRNA restored high glucose-promoted podocyte apoptosis and resulted in the reduction of p53 expression.

CONCLUSION

c-Abl contributes to high glucose-induced podocyte apoptosis via p53 signaling pathway.

c-Abl mediates angiotensin II-induced apoptosis in podocytes

Angiotensin II (Ang II) has been reported to cause podocyte apoptosis in rats both in vivo and in vitro studies. However, the underlying mechanisms are poorly understood. In the present study, we investigated the role of the nonreceptor tyrosine kinase c-Abl in Ang II-induced podocyte apoptosis. Male Sprague-Dawley rats in groups of 12 were administered either Ang II (400 kg/kg/min) or Ang II + STI-571 (50 mg/kg/day) by osmotic minipumps. In addition, 12 rats-receiving normal saline served as the control. Glomeruli c-Abl expression was carried out by real time PCR, Western blotting and immunolabeled, and occurrence of apoptosis was carried out by TUNEL staining and transmission electron microscopic analysis. In vitro studies, conditionally immortalized mouse podocytes were treated with Ang II (10(-9)-10(-6) M) in the presence or absence of either c-Abl inhibitor, Src-I1, specific c-Abl siRNA, or c-Abl plasmid alone. Quantification of podocyte c-Abl expression and c-Abl phosphorylation at Y245 and Y412 was carried out by real time PCR, Western blotting and immunofluorescence imaging. The nuclear c-Abl and p53 were quantified by co-immunoprecipitation and Western blotting studies. Podocyte apoptosis was analysed by flow cytometry and Hoechst-33342 staining. c-Abl expression was demonstrated in rat kidney podocytes in vivo and cultured mouse podocytes in vitro. Ang II-receiving rats displayed enhanced podocyte c-Abl expression. And Ang II significantly stimulated c-Abl expression in cultured podocytes. Furthermore Ang II upregulated podocyte c-Abl phosphorylation at Y245 and Y412. Ang II also induced an increase of nuclear p53 protein and nuclear c-Abl-p53 complexes in podocytes and podocyte apoptosis. Down-regulation of c-Abl expression by c-Abl inhibitor (Src-I1) as well as specific siRNA inhibited Ang II-induced podocyte apoptosis; conversely, podoctyes transfected with c-Abl plasmid displayed enhanced apoptosis. These findings indicate that c-Abl may mediates Ang II-induced podocyte apoptosis, and inhibition of c-Abl expression can protect podocytes from Ang II-induced injury.

Vesicular stomatitis virus matrix protein (VSVMP) inhibits the cell growth and tumor angiogenesis in oral squamous cell carcinoma

The purpose of this study was to investigate the anticancer property of vesicular stomatitis virus matrix protein (VSVMP) in oral squamous cell carcinoma (OSCC) via in vitro and in vivo approaches. In this study, we found that OSCC cells treated with VSVMP showed retarded cell growth in vitro. The percentage of apoptotic cells in VSVMP group was much higher than that of the control groups. Moreover, our in vivo experiments showed that the growth of tumor xenografts was significantly suppressed by VSVMP treatment without any obvious side effects. Further studies revealed that the suppression of tumor growth may be caused by the synergistic effect of VSVMP related cell apoptosis enhancing and tumor angiogenesis suppression, and the latter is most likely correlated with the suppression of VEGF pathway. This study indicated that VSVMP treatment can effectively inhibited the cell growth and tumor angiogenesis in OSCC without obvious adverse effects. Therefore, VSVMP might be a potential and efficient strategy for OSCC treatment.

Combination of vesicular stomatitis virus matrix protein gene therapy with low-dose cisplatin improves therapeutic efficacy against murine melonoma

Vesicular stomatitis virus (VSV) matrix protein (MP) can directly induce apoptosis via the mitochondrial pathway due to the inhibition of host gene expression. Our previous studies have demonstrated that MP gene therapy efficiently suppressed the growth of malignant tumor in vitro and in vivo. The present study was designed to determine the possibility that the combination of MP gene therapy with low-dose cisplatin would improve therapeutic efficacy against murine melanoma. Immunocompetent C57BL/6 mice bearing B16-F10 melanoma were established. Mice were treated once every 5 days with i.v. administration of 10 microg pVAX-MP/30 microg liposome complex per mouse for 16 days and i.p. delivery of cisplatin at 4 mg/kg/mouse on days 6 and 12 after the initiation of MP treatment. We found that MP + cisplatin treatment resulted in significant inhibition of tumor growth and improved the survival time of melanoma-bearing mice. MP successfully inhibited angiogenesis as assessed by CD31. Histological examination revealed that the combination therapy led to significant increased induction of apoptosis, tumor necrosis, and elevated CD8(+) lymphocyte infiltration. Furthermore, the induction efficacy of the CTL response was dramatically enhanced by the combination therapy. Our findings may prove useful in further explorations of the application of these combinational approaches to the treatment of malignant melanoma.

Apoptosis induction in BEFV-infected Vero and MDBK cells through Src-dependent JNK activation regulates caspase-3 and mitochondria pathways

Our previous report demonstrated that bovine ephemeral fever virus (BEFV)-infected cultured cells could induce caspase-dependent apoptosis. This study aims to further elucidate how BEFV activates the caspase cascade in bovine cells. BEFV replicated and induced apoptosis in Vero and Madin-Darby bovine kidney (MDBK) cells, and a kinetic study showed a higher efficiency of replication and a greater apoptosis induction ability of BEFV in Vero cells. Src and c-Jun N-terminal kinase (JNK) inhibitor, but not extracellular signal-regulated kinase (ERK) or p38 inhibitor, alleviated BEFV-mediated cytopathic effect and apoptosis. In BEFV-infected Vero and MDBK cells, BEFV directly induced Src tyrosine-418 phosphorylation and JNK phosphorylation and kinase activity, which was inhibited specifically by SU6656 and SP600125, respectively. The caspase cascade and its downstream effectors, Poly (ADP-ribose) polymerase (PARP) and DFF45, were also activated simultaneously upon BEFV infection. In addition, cytochrome c, but not Smac/DIABLO, was released gradually from mitochondria after BEFV infection. SU6656 suppressed Src, JNK, and caspase-3 and -9 activation, as well as PARP and DFF45 cleavage; SP600125 reduced JNK and caspase-3 and -9 activation, as well as PARP and DFF45 cleavage. Taken together, these results strongly support the hypothesis that a Src-dependent JNK signaling pathway plays a key role in BEFV-induced apoptosis. The molecular mechanism identified in our study may provide useful information for the treatment of BEFV.