Presence of ecto-protein tyrosine phosphatase activity is vital for survival of Setaria cervi, a bovine filarial parasite

Abstract

The ecto protein tyrosine phosphatases (PTP) are known to play a crucial role in the pathogenesis and survival of the intracellular parasites. However, their presence and role in filarial parasites is still unknown. We found a significant amount of tyrosine phosphatase activity in the surface antigen fraction extracted from Setaria cervi (S. cervi), a bovine filarial parasite. An antibody designed against the conserved catalytic core of human protein tyrosine phosphatases, PTP1B cross reacted with a 63 kDa band in the surface antigen. We detected a significant amount of PTP activity in the intact S. cervi adult parasites as well as microfilariae in this study for the first time. This PTP may be localized on the surface of the parasite with an exposed active site available for the external substrates. The PTP activity was also inhibited by sodium orthovanadate and phenyl arsine oxide, specific inhibitors of PTP in both the life stages. The Km and Vmax for PTP in the adult parasites and microfilariae were determined to be 2.574 ± 0.14 mM; 206.3 ± 2.75 μM Pi/h/two parasites and 5.510 ± 0.59 mM; 62.27 ± 2.27 μM Pi/h/10(6) parasites respectively using O-P-L-Tyrosine as substrate. Interestingly, a positive correlation was observed between the inhibition in PTP activity and reduction in the motility/ viability of the parasites when they were subjected to the specific PTP inhibitors (Orthovanadate and Phenyl arsine oxide) for 4 h in the KRB maintenance medium. The activity was also significantly inhibited in the parasites exposed to antifilarial drug/compounds for e.g. Diethylcarbamazine, Acetylsalicylic Acid and SK7, a methyl chalcone. Therefore suggesting a possible role played by PTP in the survival of the parasite, its interaction with the host as well as in the screening of newly synthesized antifilarials/drugs.

Identification of a novel stress regulated FERM domain containing cytosolic protein having PTP activity in Setaria cervi, a bovine filarial parasite

“…Here, in our study we have isolated, purified and characterized a novel 67 Kda PTPL cytosolic protein in S. cervi, a bovine filarial parasite. The S. cervi is used as the model organism in this study because of its nocturnal periodicity and similar antigenic pattern as that of B. malayi, the human filarial parasite [9]. The two step column chromatography enabled us to purify the 67 kDa PTPL to homogeneity.…”

“…The expression of a protein tyrosine phosphatase, ACP-1 has also been reported to be reduced in presence of PAO earlier [16]. PAO has also been reported to be lethal for these parasites too [9]. PTPL1/PTP-BAS knockdown in the astrocytoma cells leads to increase in Fasinduced apoptotic cell death whereas its reduction in case of breast cancer cells induced cell survival pathways via increase of PI3-K activity and phosphorylation of AKT kinase [17].…”

“…The monoclonal antibody (clone FG6-1G, Calbiochem, San Diego, CA) generated against the catalytic domain of a recombinant human placental PTPase 1B (1 mg/ml) as primary antibody and peroxidase conjugated rabbit anti-mouse IgG (1:5000) as secondary antibody were used as explained earlier [9]. ImageJ 7.0 software was used to quantify the western blot bands.…”