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Bacterial fucose-rich polysaccharide stabilizes MAPK-mediated Nrf2/Keap1 signaling by directly scavenging reactive oxygen species during hydrogen peroxide-induced apoptosis of human lung fibroblast cells.

Roy Chowdhury S, Sengupta S, Biswas S, Sinha TK, Sen R, Basak RK, Adhikari B, Bhattacharyya A - PLoS ONE (2014)

Bottom Line: The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H2O2)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms.H2O2 (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis.This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases).

View Article: PubMed Central - PubMed

Affiliation: Materials Science Centre, Indian Institute of Technology Kharagpur, West Bengal, India; Immunology lab, Department of Zoology, University of Calcutta, West Bengal, India.

ABSTRACT
Continuous free radical assault upsets cellular homeostasis and dysregulates associated signaling pathways to promote stress-induced cell death. In spite of the continuous development and implementation of effective therapeutic strategies, limitations in treatments for stress-induced toxicities remain. The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H2O2)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms. In two different fermentation processes, Bacillus megaterium RB-05 biosynthesized two non-identical fucose polysaccharides; of these, the polysaccharide having a high-fucose content (∼ 42%) conferred the maximum free radical scavenging efficiency in vitro. Structural characterizations of the purified polysaccharides were performed using HPLC, GC-MS, and (1)H/(13)C/2D-COSY NMR. H2O2 (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis. The polysaccharide (250 µg/mL) attenuated the cell death process by directly scavenging intracellular ROS rather than activating endogenous antioxidant enzymes. This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases). Furthermore, cellular homeostasis was re-established via stabilization of MAPK-mediated Nrf2/Keap1 signaling and transcription of downstream cytoprotective genes. This molecular study uniquely introduces a fucose-rich bacterial polysaccharide as a potential inhibitor of H2O2-induced stress and toxicities.

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Plausible signaling cross-talk involved in the HFC polysaccharide treatment against H2O2-induced apoptosis of WI38 cells.
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pone-0113663-g014: Plausible signaling cross-talk involved in the HFC polysaccharide treatment against H2O2-induced apoptosis of WI38 cells.

Mentions: MAPK signaling has been implicated in the induction of the Nrf2/Keap1 pathway by many previous reports; this may occur via phosphorylation of Nrf2 or through the nuclear translocation of Nrf2 [26]. The overexpression of JNK2 enhances site-specific phosphorylation of Nrf2 in vivo, although this phosphorylation has only a limited role in regulating Nrf2. In another study, the administration of chemical stimulants only slightly altered the ARE-dependent transcription and the protein levels of Nrf2 [26]. In the present investigation, the JNK and p38 MAPK inhibitors SP 600125 and SB 203580 significantly inhibited the nuclear translocation of Nrf2 after H2O2 exposure. This suggests that JNK and p38 MAPKs are important mediators of the Nrf2 signaling network in H2O2-treated WI38 cells. Simultaneous treatment with the HFC polysaccharide and JNK and p38 MAPKs inhibitors attenuated the phosphorylation of JNK and p38 and relocalized Nrf2 in the cytosol. Figure 14 highlights the evident crosstalk between the death-regulatory signaling system and cellular defense mechanisms.


Bacterial fucose-rich polysaccharide stabilizes MAPK-mediated Nrf2/Keap1 signaling by directly scavenging reactive oxygen species during hydrogen peroxide-induced apoptosis of human lung fibroblast cells.

Roy Chowdhury S, Sengupta S, Biswas S, Sinha TK, Sen R, Basak RK, Adhikari B, Bhattacharyya A - PLoS ONE (2014)

Plausible signaling cross-talk involved in the HFC polysaccharide treatment against H2O2-induced apoptosis of WI38 cells.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4239092&req=5

pone-0113663-g014: Plausible signaling cross-talk involved in the HFC polysaccharide treatment against H2O2-induced apoptosis of WI38 cells.
Mentions: MAPK signaling has been implicated in the induction of the Nrf2/Keap1 pathway by many previous reports; this may occur via phosphorylation of Nrf2 or through the nuclear translocation of Nrf2 [26]. The overexpression of JNK2 enhances site-specific phosphorylation of Nrf2 in vivo, although this phosphorylation has only a limited role in regulating Nrf2. In another study, the administration of chemical stimulants only slightly altered the ARE-dependent transcription and the protein levels of Nrf2 [26]. In the present investigation, the JNK and p38 MAPK inhibitors SP 600125 and SB 203580 significantly inhibited the nuclear translocation of Nrf2 after H2O2 exposure. This suggests that JNK and p38 MAPKs are important mediators of the Nrf2 signaling network in H2O2-treated WI38 cells. Simultaneous treatment with the HFC polysaccharide and JNK and p38 MAPKs inhibitors attenuated the phosphorylation of JNK and p38 and relocalized Nrf2 in the cytosol. Figure 14 highlights the evident crosstalk between the death-regulatory signaling system and cellular defense mechanisms.

Bottom Line: The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H2O2)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms.H2O2 (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis.This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases).

View Article: PubMed Central - PubMed

Affiliation: Materials Science Centre, Indian Institute of Technology Kharagpur, West Bengal, India; Immunology lab, Department of Zoology, University of Calcutta, West Bengal, India.

ABSTRACT
Continuous free radical assault upsets cellular homeostasis and dysregulates associated signaling pathways to promote stress-induced cell death. In spite of the continuous development and implementation of effective therapeutic strategies, limitations in treatments for stress-induced toxicities remain. The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H2O2)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms. In two different fermentation processes, Bacillus megaterium RB-05 biosynthesized two non-identical fucose polysaccharides; of these, the polysaccharide having a high-fucose content (∼ 42%) conferred the maximum free radical scavenging efficiency in vitro. Structural characterizations of the purified polysaccharides were performed using HPLC, GC-MS, and (1)H/(13)C/2D-COSY NMR. H2O2 (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis. The polysaccharide (250 µg/mL) attenuated the cell death process by directly scavenging intracellular ROS rather than activating endogenous antioxidant enzymes. This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases). Furthermore, cellular homeostasis was re-established via stabilization of MAPK-mediated Nrf2/Keap1 signaling and transcription of downstream cytoprotective genes. This molecular study uniquely introduces a fucose-rich bacterial polysaccharide as a potential inhibitor of H2O2-induced stress and toxicities.

Show MeSH
Related in: MedlinePlus