@article {685, title = {S-Glutathionylation of p47phox sustains superoxide generation in activated neutrophils. [Mass Spectrometry Facility - Proteomics]}, journal = {Biochim Biophys Acta}, volume = {1865}, year = {2018}, month = {2018 Feb}, pages = {444-454}, abstract = {

Post-translational modifications (PTMs) induced conformational changes of proteins can cause their activation or inactivation. Neutrophils clear pathogen through phagocytosis and oxidative burst generation, while participate in inflammation through sustained and uncontrolled generation of ROS. In activated PMNs, cytosolic NOX-2 subunit p47phox following phosphorylation interacts with p67phox, p40phox and along with Rac2 translocate to the membrane. Phosphorylation of p47phox subunit occurs in both short spurts as well as sustained ROS generation, suggesting towards the unidentified molecular mechanism(s) driving these two diverse outcomes by various stimuli. The present study demonstrates that in PMA or NO treated neutrophils a subunit of NOX2, p47phox gets glutathionylated to sustain ROS generation along with a decrease in catalase, Grx-1 activity and change in GSH/GSSG ratio. Surprisingly, fMLP treated cells neither showed sustained ROS production nor glutathionylation of p47phox. S-Glutathionylation was always secondary to phosphorylation of p47phox and inhibition of glutathionylation did not alter phosphorylation but specifically impaired sustained ROS production. Interestingly, forced S-glutathionylation of p47phox converted the fMLP induced ROS generation into sustained release of ROS. We then identified the glutathionylation susceptible cysteine residues of p47phox by LC-MS/MS with IAM switch mapping. Site-directed mutagenesis of cysteine residues further mitigated p47phox S-glutathionylation. Thus, we demonstrate that p47phox S-glutathionylation plays an essential key role in the sustained ROS generation by human neutrophils.

}, issn = {0006-3002}, doi = {10.1016/j.bbamcr.2017.11.014}, author = {Nagarkoti, Sheela and Dubey, Megha and Awasthi, Deepika and Kumar, Vikas and Chandra, Tulika and Kumar, Sachin and Dikshit, Madhu} } @article {513, title = {L-Plastin S-glutathionylation promotes reduced binding to β-actin and affects neutrophil functions. (Mass Spectrometry)}, journal = {Free Radic Biol Med}, volume = {86}, year = {2015}, month = {2015 Sep}, pages = {1-15}, abstract = {

Posttranslational modifications (PTMs) of cytoskeleton proteins due to oxidative stress associated with several pathological conditions often lead to alterations in cell function. The current study evaluates the effect of nitric oxide (DETA-NO)-induced oxidative stress-related S-glutathionylation of cytoskeleton proteins in human PMNs. By using in vitro and genetic approaches, we showed that S-glutathionylation of L-plastin (LPL) and β-actin promotes reduced chemotaxis, polarization, bactericidal activity, and phagocytosis. We identified Cys-206, Cys-283, and Cys-460as S-thiolated residues in the β-actin-binding domain of LPL, where cys-460 had the maximum score. Site-directed mutagenesis of LPL Cys-460 further confirmed the role in the redox regulation of LPL. S-Thiolation diminished binding as well as the bundling activity of LPL. The presence of S-thiolated LPL was detected in neutrophils from both diabetic patients and db/db mice with impaired PMN functions. Thus, enhanced nitroxidative stress may results in LPL S-glutathionylation leading to impaired chemotaxis, polarization, and bactericidal activity of human PMNs, providing a mechanistic basis for their impaired functions in diabetes mellitus.

}, keywords = {Actins, Adult, Amino Acid Sequence, Animals, Case-Control Studies, Cell Polarity, Chemotaxis, Diabetes Mellitus, Female, Glutathione, HEK293 Cells, Humans, Male, Mice, Inbred C57BL, Mice, Obese, Microfilament Proteins, Middle Aged, Molecular Sequence Data, Neutrophils, Nitric Oxide, Oxidative Stress, Protein Binding, Protein Processing, Post-Translational, Young Adult}, issn = {1873-4596}, doi = {10.1016/j.freeradbiomed.2015.04.008}, author = {Dubey, Megha and Singh, Abhishek K and Awasthi, Deepika and Nagarkoti, Sheela and Kumar, Sachin and Ali, Wahid and Chandra, Tulika and Kumar, Vikas and Barthwal, Manoj K and Jagavelu, Kumaravelu and S{\'a}nchez-G{\'o}mez, Francisco J and Lamas, Santiago and Dikshit, Madhu} } @article {724, title = {Neutrophil extracellular traps contain mitochondrial as well as nuclear DNA and exhibit inflammatory potential.}, journal = {Cytometry A}, volume = {81}, year = {2012}, month = {2012 Mar}, pages = {238-47}, abstract = {

Neutrophils expel extracellular traps (NETs) to entrap and exterminate the invaded micro-organisms. Acute/chronic inflammatory disorders are often observed with aberrantly enhanced NETs formation and high nitric oxide (NO) availability. Recent study from this laboratory demonstrated release of NETs from human neutrophils following treatment with SNP or SNAP. This study is an extension of our previous finding to explore the extracellular bacterial killing, source of DNA in the expelled NETs, their ability to induce proinflammatory cytokines release from platelets/THP-1 cells, and assessment of NO-mediated free radical formation by using a consistent NO donor, DETA-NONOate. NO-mediated NETs exhibited extracellular bacterial killing as determined by colony forming units. NO-mediated NETs formation was due to the activation of NADPH oxidase and myeloperoxidase. NO- or PMA-mediated NETs were positive for both nuclear and mitochondrial DNA as well as proteolytic enzymes. Incubation of NETs with human platelets enhanced the release of IL-1β and IL-8, while with THP-1 cells, release of IL-1β, IL-8, and TNFα was observed. This study demonstrates that NO by augmenting enzymatic free radical generation release NETs to promote extracellular bacterial killing. These NETs were made up of mitochondrial and nuclear DNA and potentiated release of proinflammatory cytokines.

}, keywords = {Adult, Blood Platelets, DNA, DNA, Mitochondrial, Free Radicals, Humans, Inflammation, Interleukin-1beta, Interleukin-8, Mitochondria, NADPH Oxidases, Neutrophil Activation, Neutrophils, Nitric Oxide, Peroxidase, Tumor Necrosis Factor-alpha}, issn = {1552-4930}, doi = {10.1002/cyto.a.21178}, author = {Keshari, Ravi S and Jyoti, Anupam and Kumar, Sachin and Dubey, Megha and Verma, Anupam and Srinag, Bangalore S and Krishnamurthy, Hanumanthappa and Barthwal, Manoj K and Dikshit, Madhu} }