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 infection of HSAECs by ZH501 strain of RVFV.A) 106 HSAECs were infected with the ZH501 strain of RVFV. Western blots were carried out using cell extracts obtained at 30, 48 and 72 h post infection for expression of viral proteins using anti-RVFV antibodies. B) Extracts of uninfected control cells and infected cells were resolved on SDS gels and western blots performed with anti-SOD1 antibody. Actin was used as a loading control. C) The same cell extracts used in B) were used for analysis of phosphorylated forms of VEGF-receptor, MKK3/6, p38 MAPK, and Hsp27 with specific antibodies. Actin was a loading control. D) Cell extracts obtained 48 and 72 h post infection were analyzed by western blot using antibodies to total p38 MAPK (t-p38) and Hsp27 (t-Hsp27) proteins. All data are representative of at least two independent experiments.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3105056&req=5

pone-0020354-g007: Effects of infection of HSAECs by ZH501 strain of RVFV.A) 106 HSAECs were infected with the ZH501 strain of RVFV. Western blots were carried out using cell extracts obtained at 30, 48 and 72 h post infection for expression of viral proteins using anti-RVFV antibodies. B) Extracts of uninfected control cells and infected cells were resolved on SDS gels and western blots performed with anti-SOD1 antibody. Actin was used as a loading control. C) The same cell extracts used in B) were used for analysis of phosphorylated forms of VEGF-receptor, MKK3/6, p38 MAPK, and Hsp27 with specific antibodies. Actin was a loading control. D) Cell extracts obtained 48 and 72 h post infection were analyzed by western blot using antibodies to total p38 MAPK (t-p38) and Hsp27 (t-Hsp27) proteins. All data are representative of at least two independent experiments.

Mentions: We then asked whether similar host responses observed due to MP12 infection can be seen when human cells were infected with the pathogenic ZH501 strain of RVFV (MOI of 0.002). HSAECs were infected with ZH501 strain and extracts were analyzed at multiple time points following infection by western blots. ZH501 infections were carried out at a lower MOI than the MP12 infections because of the strong cytopathogenecity of the virulent strain that is observed in comparison with the MP12 strain. Our results demonstrated that SOD1 levels were reduced at 24 and 30 h following infection (Figure 7B). When we evaluated the activation of the p38 MAPK pathway, we observed that p38 MAPK and its upstream kinase MKK3/6 were strongly phosphorylated between 48 and 72 h post infection. The difference in the time of activation of p38 between the MP12 strain and the ZH501 strain may be possibly due to difference in the MOI employed and differences in the inherent pathogenecities of the two strains. We also analyzed the activation status of Hsp27, a chaperone that is a downstream target of activated p38 MAPK and saw that the molecule was phosphorylated (Figure 7C). One of the upstream activators of the p38 MAPK cascade is the VEGF receptor. Our experiments did not reveal any significant increase in phosphorylation of the VEGF receptor. There was however, no change in the total protein levels of p38 MAPK and Hsp27 under these conditions (Figure 7D). Collectively, our data demonstrate that following exposure to ZH501 strain of RVFV, human cells undergo similar alterations in SOD1 protein levels and elicit similar responses as observed in the case of a MP12 infection.


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 infection of HSAECs by ZH501 strain of RVFV.A) 106 HSAECs were infected with the ZH501 strain of RVFV. Western blots were carried out using cell extracts obtained at 30, 48 and 72 h post infection for expression of viral proteins using anti-RVFV antibodies. B) Extracts of uninfected control cells and infected cells were resolved on SDS gels and western blots performed with anti-SOD1 antibody. Actin was used as a loading control. C) The same cell extracts used in B) were used for analysis of phosphorylated forms of VEGF-receptor, MKK3/6, p38 MAPK, and Hsp27 with specific antibodies. Actin was a loading control. D) Cell extracts obtained 48 and 72 h post infection were analyzed by western blot using antibodies to total p38 MAPK (t-p38) and Hsp27 (t-Hsp27) proteins. All data are representative of at least two independent experiments.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0020354-g007: Effects of infection of HSAECs by ZH501 strain of RVFV.A) 106 HSAECs were infected with the ZH501 strain of RVFV. Western blots were carried out using cell extracts obtained at 30, 48 and 72 h post infection for expression of viral proteins using anti-RVFV antibodies. B) Extracts of uninfected control cells and infected cells were resolved on SDS gels and western blots performed with anti-SOD1 antibody. Actin was used as a loading control. C) The same cell extracts used in B) were used for analysis of phosphorylated forms of VEGF-receptor, MKK3/6, p38 MAPK, and Hsp27 with specific antibodies. Actin was a loading control. D) Cell extracts obtained 48 and 72 h post infection were analyzed by western blot using antibodies to total p38 MAPK (t-p38) and Hsp27 (t-Hsp27) proteins. All data are representative of at least two independent experiments.
Mentions: We then asked whether similar host responses observed due to MP12 infection can be seen when human cells were infected with the pathogenic ZH501 strain of RVFV (MOI of 0.002). HSAECs were infected with ZH501 strain and extracts were analyzed at multiple time points following infection by western blots. ZH501 infections were carried out at a lower MOI than the MP12 infections because of the strong cytopathogenecity of the virulent strain that is observed in comparison with the MP12 strain. Our results demonstrated that SOD1 levels were reduced at 24 and 30 h following infection (Figure 7B). When we evaluated the activation of the p38 MAPK pathway, we observed that p38 MAPK and its upstream kinase MKK3/6 were strongly phosphorylated between 48 and 72 h post infection. The difference in the time of activation of p38 between the MP12 strain and the ZH501 strain may be possibly due to difference in the MOI employed and differences in the inherent pathogenecities of the two strains. We also analyzed the activation status of Hsp27, a chaperone that is a downstream target of activated p38 MAPK and saw that the molecule was phosphorylated (Figure 7C). One of the upstream activators of the p38 MAPK cascade is the VEGF receptor. Our experiments did not reveal any significant increase in phosphorylation of the VEGF receptor. There was however, no change in the total protein levels of p38 MAPK and Hsp27 under these conditions (Figure 7D). Collectively, our data demonstrate that following exposure to ZH501 strain of RVFV, human cells undergo similar alterations in SOD1 protein levels and elicit similar responses as observed in the case of a MP12 infection.

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