Limits...
Alteration in superoxide dismutase 1 causes oxidative stress and p38 MAPK activation following RVFV infection.

Narayanan A, Popova T, Turell M, Kidd J, Chertow J, Popov SG, Bailey C, Kashanchi F, Kehn-Hall K - PLoS ONE (2011)

Bottom Line: Understanding early host events to an infectious exposure to RVFV will be of significant use in the development of effective therapeutics that not only control pathogen multiplication, but also contribute to cell survival.Alterations in the host protein SOD1 following RVFV infection appears to be an early event that occurs in multiple cell types.Our data implies that maintaining oxidative homeostasis in the infected cells may play an important role in improving survival of infected cells.

View Article: PubMed Central - PubMed

Affiliation: National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, Virginia, United States of America.

ABSTRACT
Rift Valley fever (RVF) is a zoonotic disease caused by Rift Valley fever virus (RVFV). RVFV is a category A pathogen that belongs to the genus Phlebovirus, family Bunyaviridae. Understanding early host events to an infectious exposure to RVFV will be of significant use in the development of effective therapeutics that not only control pathogen multiplication, but also contribute to cell survival. In this study, we have carried out infections of human cells with a vaccine strain (MP12) and virulent strain (ZH501) of RVFV and determined host responses to viral infection. We demonstrate that the cellular antioxidant enzyme superoxide dismutase 1 (SOD1) displays altered abundances at early time points following exposure to the virus. We show that the enzyme is down regulated in cases of both a virulent (ZH501) and a vaccine strain (MP12) exposure. Our data demonstrates that the down regulation of SOD1 is likely to be due to post transcriptional processes and may be related to up regulation of TNFα following infection. We also provide evidence for extensive oxidative stress in the MP12 infected cells. Concomitantly, there is an increase in the activation of the p38 MAPK stress response, which our earlier published study demonstrated to be an essential cell survival strategy. Our data suggests that the viral anti-apoptotic protein NSm may play a role in the regulation of the cellular p38 MAPK response. Alterations in the host protein SOD1 following RVFV infection appears to be an early event that occurs in multiple cell types. Activation of the cellular stress response p38 MAPK pathway can be observed in all cell types tested. Our data implies that maintaining oxidative homeostasis in the infected cells may play an important role in improving survival of infected cells.

Show MeSH

Related in: MedlinePlus

Effects of MP12 infection on SOD1 and p38 MAPK in HepG2 and 293T cells.A) 106 HepG2 cells were infected with MP12 virus (MOI of 3) and extracts were obtained at 24, 48 and 72 h post infection. Western blots were carried out with antibodies to SOD1, phospho-p38 MAPK (p-p38), Total p38 MAPK (t-p38) and RVFV (Gc). B) 106 293T cells were infected with MP12 virus and analyzed by western blots as described above.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3105056&req=5

pone-0020354-g006: Effects of MP12 infection on SOD1 and p38 MAPK in HepG2 and 293T cells.A) 106 HepG2 cells were infected with MP12 virus (MOI of 3) and extracts were obtained at 24, 48 and 72 h post infection. Western blots were carried out with antibodies to SOD1, phospho-p38 MAPK (p-p38), Total p38 MAPK (t-p38) and RVFV (Gc). B) 106 293T cells were infected with MP12 virus and analyzed by western blots as described above.

Mentions: In order to determine if similar effects of infection are observed in different cell types, we infected HepG2 and 293T cells with MP12 virus (MOI of 3). We chose these cell types because HepG2 cells are liver cells and liver is a prominently affected organ in RVF. 293T cells were utilized in a recent study that screened small molecule inhibitors of RVFV and were shown to be significantly infected by RVFV [42]. Viral infection was confirmed in all cases by western blots for viral protein (data not shown). Following infection of HepG2s with MP12, we obtained cell extracts at 24, 48 and 72 h post infection. We carried out western blot analysis to determine if there is a change in the SOD1 levels in these cells. We found that similar to what we observed with the HSAECs, HepG2s showed lowered SOD1 levels at earlier time points following infection (Figure 6A, red circles). Similar to our observation in HSAECs, we also saw increased phosphorylation of p38 MAPK that peaked at 48 h post infection. Total p38 MAPK displayed only a marginal increase at all time points in the infected sample when compared to the control sample suggesting that, similar to our observations in HSAECs, the increase in phosphorylated p38 MAPK was not dependent on increased expression. Our analysis of 293T cells followed this general trend, in that, there was an early down regulation of SOD1 (Figure 6B, red circles). Interestingly, we also observed a prolonged activation of p38 MAPK as the phosphorylated form was observed up to 72 h post infection. Total p38 MAPK remained largely unchanged. Over all, the data from multiple cell types suggest that early down regulation of SOD1 and activation of p38 MAPK may be common phenomena following infection by RVFV.


Alteration in superoxide dismutase 1 causes oxidative stress and p38 MAPK activation following RVFV infection.

Narayanan A, Popova T, Turell M, Kidd J, Chertow J, Popov SG, Bailey C, Kashanchi F, Kehn-Hall K - PLoS ONE (2011)

Effects of MP12 infection on SOD1 and p38 MAPK in HepG2 and 293T cells.A) 106 HepG2 cells were infected with MP12 virus (MOI of 3) and extracts were obtained at 24, 48 and 72 h post infection. Western blots were carried out with antibodies to SOD1, phospho-p38 MAPK (p-p38), Total p38 MAPK (t-p38) and RVFV (Gc). B) 106 293T cells were infected with MP12 virus and analyzed by western blots as described above.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105056&req=5

pone-0020354-g006: Effects of MP12 infection on SOD1 and p38 MAPK in HepG2 and 293T cells.A) 106 HepG2 cells were infected with MP12 virus (MOI of 3) and extracts were obtained at 24, 48 and 72 h post infection. Western blots were carried out with antibodies to SOD1, phospho-p38 MAPK (p-p38), Total p38 MAPK (t-p38) and RVFV (Gc). B) 106 293T cells were infected with MP12 virus and analyzed by western blots as described above.
Mentions: In order to determine if similar effects of infection are observed in different cell types, we infected HepG2 and 293T cells with MP12 virus (MOI of 3). We chose these cell types because HepG2 cells are liver cells and liver is a prominently affected organ in RVF. 293T cells were utilized in a recent study that screened small molecule inhibitors of RVFV and were shown to be significantly infected by RVFV [42]. Viral infection was confirmed in all cases by western blots for viral protein (data not shown). Following infection of HepG2s with MP12, we obtained cell extracts at 24, 48 and 72 h post infection. We carried out western blot analysis to determine if there is a change in the SOD1 levels in these cells. We found that similar to what we observed with the HSAECs, HepG2s showed lowered SOD1 levels at earlier time points following infection (Figure 6A, red circles). Similar to our observation in HSAECs, we also saw increased phosphorylation of p38 MAPK that peaked at 48 h post infection. Total p38 MAPK displayed only a marginal increase at all time points in the infected sample when compared to the control sample suggesting that, similar to our observations in HSAECs, the increase in phosphorylated p38 MAPK was not dependent on increased expression. Our analysis of 293T cells followed this general trend, in that, there was an early down regulation of SOD1 (Figure 6B, red circles). Interestingly, we also observed a prolonged activation of p38 MAPK as the phosphorylated form was observed up to 72 h post infection. Total p38 MAPK remained largely unchanged. Over all, the data from multiple cell types suggest that early down regulation of SOD1 and activation of p38 MAPK may be common phenomena following infection by RVFV.

Bottom Line: Understanding early host events to an infectious exposure to RVFV will be of significant use in the development of effective therapeutics that not only control pathogen multiplication, but also contribute to cell survival.Alterations in the host protein SOD1 following RVFV infection appears to be an early event that occurs in multiple cell types.Our data implies that maintaining oxidative homeostasis in the infected cells may play an important role in improving survival of infected cells.

View Article: PubMed Central - PubMed

Affiliation: National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, Virginia, United States of America.

ABSTRACT
Rift Valley fever (RVF) is a zoonotic disease caused by Rift Valley fever virus (RVFV). RVFV is a category A pathogen that belongs to the genus Phlebovirus, family Bunyaviridae. Understanding early host events to an infectious exposure to RVFV will be of significant use in the development of effective therapeutics that not only control pathogen multiplication, but also contribute to cell survival. In this study, we have carried out infections of human cells with a vaccine strain (MP12) and virulent strain (ZH501) of RVFV and determined host responses to viral infection. We demonstrate that the cellular antioxidant enzyme superoxide dismutase 1 (SOD1) displays altered abundances at early time points following exposure to the virus. We show that the enzyme is down regulated in cases of both a virulent (ZH501) and a vaccine strain (MP12) exposure. Our data demonstrates that the down regulation of SOD1 is likely to be due to post transcriptional processes and may be related to up regulation of TNFα following infection. We also provide evidence for extensive oxidative stress in the MP12 infected cells. Concomitantly, there is an increase in the activation of the p38 MAPK stress response, which our earlier published study demonstrated to be an essential cell survival strategy. Our data suggests that the viral anti-apoptotic protein NSm may play a role in the regulation of the cellular p38 MAPK response. Alterations in the host protein SOD1 following RVFV infection appears to be an early event that occurs in multiple cell types. Activation of the cellular stress response p38 MAPK pathway can be observed in all cell types tested. Our data implies that maintaining oxidative homeostasis in the infected cells may play an important role in improving survival of infected cells.

Show MeSH
Related in: MedlinePlus