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

• Published in: PloS one Vol. 9; no. 11; p. e113663
• Main Authors: Roy Chowdhury, Sougata, Sengupta, Suman, Biswas, Subir, Sinha, Tridib Kumar, Sen, Ramkrishna, Basak, Ratan Kumar, Adhikari, Basudam, Bhattacharyya, Arindam
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.11.2014; Public Library of Science (PLoS)
• Subjects: Antioxidants; Antioxidants (Nutrients); Apoptosis; Apoptosis - drug effects; Bacillus megaterium - metabolism; Bacteria; BAX protein; Biology and Life Sciences; Carbohydrate Sequence; Caspase; Caspase-9; Caspases - metabolism; Cell death; Cell Line; Cell Membrane Permeability - drug effects; Cell Proliferation - drug effects; Cytochrome; Cytochrome c; Cytochromes c - metabolism; Fermentation; Fibroblasts; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; Free Radical Scavengers - analysis; Free Radical Scavengers - chemistry; Free Radical Scavengers - pharmacology; Free radicals; Fucose; Fucose - chemistry; Fucose - metabolism; Gene expression; Health aspects; High-performance liquid chromatography; Homeostasis; Humans; Hydrogen; Hydrogen peroxide; Hydrogen Peroxide - toxicity; Immunology; Intracellular; Intracellular Signaling Peptides and Proteins - metabolism; Kelch-Like ECH-Associated Protein 1; Kinases; Liquid chromatography; Lung - cytology; Lungs; MAP kinase; Materials science; Membrane permeability; Metabolism; Microbial polysaccharides; Mitochondria; Mitochondria - metabolism; Mitogen-Activated Protein Kinases - metabolism; Molecular modelling; Molecular Sequence Data; NF-E2-Related Factor 2 - metabolism; NMR; Nuclear magnetic resonance; Oxidative stress; Oxygen; Permeability; Phosphorylation; Phosphotransferases; Physiology; Polysaccharides; Polysaccharides, Bacterial - analysis; Polysaccharides, Bacterial - chemistry; Polysaccharides, Bacterial - pharmacology; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Rodents; Saccharides; Scavenging; Signal Transduction - drug effects; Signaling; Stresses; Studies; Toxicity; Transcription; Zoology; West Bengal India; India
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0113663

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.