Browsing by Author "Mohit Wadhawan"

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Effect of CDNB on filarial thioredoxin reductase : A proteomic and biochemical approach
(Elsevier, 2015) Savitri Tiwari; Mohit Wadhawan; Neetu Singh; Sushma Rathaur
Thioredoxin reductase plays a crucial role in the maintenance of cellular redox homeostasis. In this study, we have targeted TrxR in Setaria cervi, a bovine filarial parasite using its inhibitor CDNB. It caused significant decrease in the motility and viability of these parasites leading to their death. Inhibition of TrxR leads to the downregulation of the antioxidant system followed by generation of oxidative stress in these parasites. The increased ROS level induced lipid peroxidation and protein carbonyl formation which might alter the mitochondrial membrane permeability leading to release of cytochrome c. CDNB significantly downregulated the level of ced-9 and activity of tyrosine phosphatases, cytochrome c oxidase. It also upregulated ced-3, homolog of mammalian caspase 3 suggesting initiation of intrinsic pathway of apoptosis. The proteomic profile of CDNB treated parasites showed marked alteration in abundance of different protein spots with 20% downregulated and 13% unregulated spots in comparison to control parasites. We observed a downregulation in the glycolytic enzymes such as enolase, PGK, and GAPDH thereby blocking the ATP formation in the parasite. This study suggests that TrxR inhibition disrupts the cellular homeostasis thereby generating oxidative stress followed by mitochondrial mediated apoptosis in filarial parasites leading to the death of the parasites. Biological significance: Lymphatic filariasis is one of the most prevalent tropical diseases caused by tissue dwelling parasitic nematodes viz., Wuchereria bancrofti, Brugia malayi and Brugia timori. Currently available antifilarial drugs effectively eliminate larval stages of the parasite but are ineffective against the adult worms. Therefore, there is an urgent need for finding proteins/enzymes which play a crucial role in the persistence of these parasites. Our study for the first time reports the important role played by S. cervi TrxR in its survival. Thus, suggesting filarial TrxR as a potent chemotherapeutic target against lymphatic filariasis. This would help in screening of new compounds having macrofilaricidal activity. © 2014 Elsevier B.V.
Identification and characterization of a novel prolyl oligopeptidase in filarial parasite Setaria cervi
(Elsevier B.V., 2018) Mohit Wadhawan; Savitri Tiwari; Shweta Sharma; Sushma Rathaur
A 75 kDa serine protease having prolyl oligopeptidase activity has been purified from Setaria cervi, a bovine filarial parasite. The MALDI-MS/MS analysis of the purified protein revealed 6 peptides showing nearest match S9A (prolyl oligopeptidase) family protein from Plesiocystis pacifica. The ScPOP was found to be unique compared to mammalian POP with respect to its kinetic properties. To elucidate its role, filarial parasites were exposed to specific inhibitor of POP, Z-Pro-prolinal (ZPP) for 8 h. The inhibition of POP induced calcium signaling via phospholipase c stimulation which further triggered mitochondrial mediated apoptosis in filarial parasites. © 2017 Elsevier Inc.
Inhibition of cathepsin B by E-64 induces oxidative stress and apoptosis in filarial parasite
(Public Library of Science, 2014) Mohit Wadhawan; Neetu Singh; Sushma Rathaur
Background: Current available antifilarial drug strategies only eliminate the larval stages of filarial parasites. Therefore, there is an urgent need of drugs which are macrofilaricidals. Identification of molecular targets crucial for survival of parasite is a prerequisite for drug designing. Cathepsin B, a cysteine protease family member is known to play crucial role in the normal growth, digestion of nutrients, exsheathment of the helminth parasites. Therefore, we targeted this enzyme in the filarial parasite using its specific inhibitor, E-64. Methods and Findings: We have exposed the parasites to E-64 and observed their motility and viability at various time intervals. It caused marked decrease in the motility and viability of the parasites ultimately leading to their death after 8 hours. It is well known that E-64 protects the cell from apoptosis, however, it causes apoptotic effect in carcinoma cell lines. To understand the mechanism of action of E-64 on parasite survival, we have measured levels of different apoptotic markers in the treated parasites. E-64 significantly reduced the level of ced-9 and activity of tyrosine phosphatases, cytochrome c oxidase. It also activated ced-3, homolog of mammalian caspase 3 suggesting initiation of an apoptotic like event in the filarial parasites. Different antioxidant enzymes were also evaluated to further explore the mechanism behind the death of the parasites. There was marked decrease in the level of GSH and activity of Glutathione reductase and glutathione-s-transferase leading to increased generation of reactive oxygen species. This led to the induced oxidation of fatty acids and protein which might alter the mitochondrial membrane permeability. Conclusion: This study suggests that inhibition of cathepsin B by E-64 generates oxidative stress followed by mitochondrial mediated apoptotic like event in filarial parasites leading to their death. Hence, suggesting filarial cathepsin B as a potential chemotherapeutic target for lymphatic filariasis. © 2014 Wadhawan et al.
Inhibition of Setaria cervi protein tyrosine phosphatases by Phenylarsine oxide: A proteomic and biochemical study
(Elsevier B.V., 2016) Neetu Singh; Mohit Wadhawan; Savitri Tiwari; Ranjeet Kumar; Sushma Rathaur
Phenylarsine oxide (PAO), a specific protein tyrosine phosphatase (PTP) inhibitor significantly decreased the motility and viability of Setaria cervi ultimately leading to its death. The PTP activity present in the cytosolic and detergent soluble fractions as well as on surface of these parasites was significantly inhibited by PAO. A marked alteration in protein spots abundance after proteomic analysis showed 14 down-regulated and 9 upregulated spots in the treated parasites as compared to the control. The PTP inhibition led to increase in the cytosolic and mitochondrial calpain activity in these parasites. PAO also blocked the ATP generation in the parasite depicted by reduced activity of phosphoglycerate kinase and expression of enolase. An increased ROS level, induced lipid peroxidation/protein carbonyl formation and decreased activity of different antioxidant enzymes like thioredoxin reductase, glutathione reductase and glutathione transferases was also observed in the PAO treated parasites. PAO, thus disturbs the overall homeostasis of the filarial parasite by inhibiting PTPs. Thereby suggesting that these molecules could be used as a good chemotherapeutic target for lymphatic filariasis. © 2016 Elsevier B.V.
Proteomic Analysis Reveals Differential Protein Expression Induced by Inhibition of Prolyl Oligopeptidase in Filarial Parasites
(Springer, 2022) Mohit Wadhawan; Faiyaz Ahmad; Smita Yadav; Sushma Rathaur
Prolyl oligopeptidase (POP) plays a crucial role in the processing and degradation of neuropeptides and regulates inositol trisphosphate (IP3) signaling in mammals. We have reported that POP inhibition leads to IP3-mediated calcium efflux leading to mitochondrial-mediated apoptosis in the filarial parasite Setaria cervi. This study further elucidates the effect of altered calcium homeostasis on the proteome of filarial parasites. Adult parasites were treated with POP’s specific inhibitor, Z-Pro-prolinal (ZPP), for 7 h. Cytosolic and mitochondrial proteome was analyzed using 2D gel electrophoresis coupled with MALDI-MS/MS. Phosphoproteins were also analyzed in the cytosolic fraction of the parasites. The phosphoprotein analysis revealed 7, and 9 spots in the cytosolic fraction of control and ZPP-treated parasites, respectively. The two identified protein spots in the treated set were found to be involved in G protein signaling. In cytosolic fraction, 109 and 112 protein spots were observed in control and treated parasites, respectively. Of these, 56 upregulated and 32 downregulated protein spots were observed in the treated set. On the other hand, 50 and 47 protein spots were detected in the mitochondrial fraction of control and treated parasites, respectively. Of these spots, 18 upregulated and 12 down-regulated protein spots were found in treated parasites. In silico analysis showed that the identified proteins were involved in energy metabolism, calcium signaling, stress response, and cytoskeleton organization. These findings correlate with our previous results suggesting the important regulatory role of POP in signaling and different metabolic pathways of filarial parasites. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.