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Ultrastructures of larvae during normal molting and larvae that did not molt in the presence of the MDC inhibitor. L3 during normal molting were collected on days 1, 2, and 3, and L3 that did not molt in the presence of 150 and 200 M MDC were collected on day 6. Thin sections of larvae during the normal molting process for larvae on day 1 (a), day 2 (b), and day 3 (c) and thin sections of three different worms that did not molt in the presence of MDC (d, e, and f) are presented (bars, 0.25 m). Separations between the L4 epicuticle and the L3 cuticle are marked by arrows and arrowheads, respectively.
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Highly insoluble proteins, which are probably cross-linked, are common in the cuticle and epicuticle of filarial parasites and other nematode species. We have investigated the possible involvement of transglutami- nase (TGase)-catalyzed reactions in the development ofOnchocerca volvulusfourth-stage larvae (L4) by testing the effects of TGase inhibi...
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... of larvae that did not molt in the presence of TGase inhibitors. O. volvulus larvae that did not molt in cultures containing the MDC or CS inhibitors continuously were collected and processed for electron microscopy. As shown in Fig. 3d, e, and f, the larvae that did not molt in the presence of MDC had initiated the molting process but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized ...
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... TGase inhibitors. O. volvulus larvae that did not molt in cultures containing the MDC or CS inhibitors continuously were collected and processed for electron microscopy. As shown in Fig. 3d, e, and f, the larvae that did not molt in the presence of MDC had initiated the molting process but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cultures on ...
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... in Fig. 3d, e, and f, the larvae that did not molt in the presence of MDC had initiated the molting process but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cultures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, ...
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... but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cultures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, respec- tively). The cuticular ultrastructures of the larvae that did not molt in the presence of CS were similar to ...
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... 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cultures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, respec- tively). The cuticular ultrastructures of the larvae that did not molt in the presence of CS were similar to the ones cultured in the presence of MDC (data not ...
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... to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cultures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, respec- tively). The cuticular ultrastructures of the larvae that did not molt in the presence of CS were similar to the ones cultured in the presence of MDC (data not ...
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... AND MOLTING OF ONCHOCERCA LARVAEcuticle (Fig. 5a, arrowhead) and the separation between the two cuticles below the old basal layer of L3 (Fig. 5b, arrowhead), as seen during normal molting ( Fig. 3a and b). The monoclonal antibody recognized the isopeptide mostly in areas around the region where the separation between the cuticles takes place, in some areas of the cuticle of the newly formed L4, and in the lower part of the old cuticle, where the separation occurs ( Fig. 5a and b). Interestingly, the density of staining is higher in the ...
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... larval proteins that serve as a substrate(s) for TGase-catalyzed cross-linking of proteins, and CS, the activesite inhibitor, had to be present during the first 24 to 48 h, the beginning of the molting process, to exert a complete inhibitory effect (Fig. 2). After the third day in culture, when complete separation of the cuticle usually occurs (Fig. 3c), a complete inhibitory effect was not observed. These findings implied that the effect of the inhibitors was specific to some of the first changes that occur in the cuticle during the molting process: development of the new L4 epicuticle and cuticle and the beginning of the separation between the cuticles (Fig. 3a and 5a). This ...
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... of the cuticle usually occurs (Fig. 3c), a complete inhibitory effect was not observed. These findings implied that the effect of the inhibitors was specific to some of the first changes that occur in the cuticle during the molting process: development of the new L4 epicuticle and cuticle and the beginning of the separation between the cuticles (Fig. 3a and 5a). This conclusion is supported by the ultrastructural studies (Fig. 3d to f). Larvae that did not molt in the presence of the inhibitors were found to be at the different stages of development that precede complete separation between the cuticles. Some larvae had visible L4 epicuticles and cuticles, and in some we observed irregular ...
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... observed. These findings implied that the effect of the inhibitors was specific to some of the first changes that occur in the cuticle during the molting process: development of the new L4 epicuticle and cuticle and the beginning of the separation between the cuticles (Fig. 3a and 5a). This conclusion is supported by the ultrastructural studies (Fig. 3d to f). Larvae that did not molt in the presence of the inhibitors were found to be at the different stages of development that precede complete separation between the cuticles. Some larvae had visible L4 epicuticles and cuticles, and in some we observed irregular separations between the L4 epicuticle and the L3 cuticle. However, we never ...
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... were found to be at the different stages of development that precede complete separation between the cuticles. Some larvae had visible L4 epicuticles and cuticles, and in some we observed irregular separations between the L4 epicuticle and the L3 cuticle. However, we never observed within unmolted larvae a complete separation between the cuticles (Fig. 3b and c). This indicated that when we generated inhibition of TGase-catalyzed reactions we indirectly prevented the complete separation between the cuticles and consequently ecdysis, shedding of the old cuticle. Second, the product of a TGase-catalyzed reaction, the isopeptide ε-(-glutamyl)-lysine, was found to be mostly localized in the lower ...
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... of larvae that did not molt in the presence of TGase inhibitors. O. volvulus larvae that did not molt in cul- tures containing the MDC or CS inhibitors continuously were collected and processed for electron microscopy. As shown in Fig. 3d, e, and f, the larvae that did not molt in the presence of MDC had initiated the molting process but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized ...
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... inhibitors. O. volvulus larvae that did not molt in cul- tures containing the MDC or CS inhibitors continuously were collected and processed for electron microscopy. As shown in Fig. 3d, e, and f, the larvae that did not molt in the presence of MDC had initiated the molting process but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cul- tures ...
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... in Fig. 3d, e, and f, the larvae that did not molt in the presence of MDC had initiated the molting process but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cul- tures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, ...
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... but never completed it as it happens under normal conditions (Fig. 3c). The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cul- tures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, respec- tively). The cuticular ultrastructures of the larvae that did not molt in the presence of CS were similar to ...
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... The larvae had a visible L4 epicuticle and cuticle, in addition to the outer L3 epicuticle and cuticle, indicating that the new L4 cuticle had begun to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cul- tures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, respec- tively). The cuticular ultrastructures of the larvae that did not molt in the presence of CS were similar to the ones cultured in the presence of MDC (data not ...
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... to be synthesized (Fig. 3d). In some larvae, irregular separations between the L4 epicuticle and the L3 cuticle were observed ( Fig. 3e and f), similar to those seen in normal cul- tures on day 1 (Fig. 3a). However, we could not find any larvae in which the separation between the cuticles was complete, as seen in normal cultures on days 2 and 3 ( Fig. 3b and c, respec- tively). The cuticular ultrastructures of the larvae that did not molt in the presence of CS were similar to the ones cultured in the presence of MDC (data not ...
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... AND MOLTING OF ONCHOCERCA LARVAEcuticle (Fig. 5a, arrowhead) and the separation between the two cuticles below the old basal layer of L3 (Fig. 5b, arrow- head), as seen during normal molting ( Fig. 3a and b). The monoclonal antibody recognized the isopeptide mostly in areas around the region where the separation between the cuticles takes place, in some areas of the cuticle of the newly formed L4, and in the lower part of the old cuticle, where the separa- tion occurs ( Fig. 5a and b). Interestingly, the density of staining is higher in ...
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... larval proteins that serve as a substrate(s) for TGase-catalyzed cross-linking of proteins, and CS, the active- site inhibitor, had to be present during the first 24 to 48 h, the beginning of the molting process, to exert a complete inhibitory effect (Fig. 2). After the third day in culture, when complete separation of the cuticle usually occurs (Fig. 3c), a complete inhibitory effect was not observed. These findings implied that the effect of the inhibitors was specific to some of the first changes that occur in the cuticle during the molting process: development of the new L4 epicuticle and cuticle and the beginning of the separation between the cuticles (Fig. 3a and 5a). This ...
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... of the cuticle usually occurs (Fig. 3c), a complete inhibitory effect was not observed. These findings implied that the effect of the inhibitors was specific to some of the first changes that occur in the cuticle during the molting process: development of the new L4 epicuticle and cuticle and the beginning of the separation between the cuticles (Fig. 3a and 5a). This conclusion is supported by the ultrastructural studies (Fig. 3d to f). Larvae that did not molt in the presence of the inhibitors were found to be at the different stages of development that precede complete separation between the cuticles. Some larvae had visible L4 epi- cuticles and cuticles, and in some we observed irregular ...
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... observed. These findings implied that the effect of the inhibitors was specific to some of the first changes that occur in the cuticle during the molting process: development of the new L4 epicuticle and cuticle and the beginning of the separation between the cuticles (Fig. 3a and 5a). This conclusion is supported by the ultrastructural studies (Fig. 3d to f). Larvae that did not molt in the presence of the inhibitors were found to be at the different stages of development that precede complete separation between the cuticles. Some larvae had visible L4 epi- cuticles and cuticles, and in some we observed irregular separa- tions between the L4 epicuticle and the L3 cuticle. However, we never ...
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... found to be at the different stages of development that precede complete separation between the cuticles. Some larvae had visible L4 epi- cuticles and cuticles, and in some we observed irregular separa- tions between the L4 epicuticle and the L3 cuticle. However, we never observed within unmolted larvae a complete separation between the cuticles (Fig. 3b and c). This indicated that when we generated inhibition of TGase-catalyzed reactions we indirectly prevented the complete separation between the cuticles and con- sequently ecdysis, shedding of the old cuticle. Second, the product of a TGase-catalyzed reaction, the isopeptide ε-(-glutamyl)- lysine, was found to be mostly localized in the ...
Citations
... MDC also exhibited macrolaricidal as well as embryostatic effects when tested in vitro against A. viteae adult worms. [197][198][199][200][201][202] Following administration to B. malayi, retinoic acid was taken up and localized in early and late embryonic forms at high concentrations, suggesting that they may play a role in its growth and development. 203 The comparative amounts of retinoic acid-binding proteins (RABPs) were between 2.7 and 3.1 pmol of retinoic acid bound/mg of extractable protein in larids (D. viteae, B. pahangi). ...
Filariasis is one of the oldest, most debilitating, disabling, and disfiguring neglected tropical diseases with various clinical manifestations and a low rate of mortality, but has a high morbidity rate, which results in social stigma. According to the WHO estimation, about 120 million people from 81 countries are infected at present and an estimated 1.34 billion people live in areas endemic to filariasis and are at risk of infection. In this review, we focus on Lymphatic Filariasis (LF) and provide brief insights on some other filarial conditions. Current drug treatments have beneficial effects in the elimination of only the larval stage of the worms. Very few drugs are available for treatment of filariasis but their repetitive use may give rise to drug resistance. They are also found to be fairly ineffective towards eliminating adult worms. Moreover, no effective vaccine is available for treatment of filariasis. Because of these limitations, development of new antifilarials has been of utmost importance, a fact which encourages researchers to discover new drugs having antifilarial activity. Herein we extensively review developments in the field of antifilarials including the types of filariasis, their historical perspectives, eradication programs, different classes of drug (i.e. synthetic as well as natural), explored product-derived different targets, patents and clinical trials.
... 21 The glandular tissue is packed with secretory structures and rough endoplasmic reticulum, 21 signifying an enhanced rate of protein synthesis crucial for the development of the L3 larvae. Enzymes such as cysteine proteases, 22 serine proteases, 23 transglutaminases, 24 and chitinases 2 have earlier been implicated in the L3-to-L4 molt of O. volvulus. Thus, the uncoupling of mitochondrial activity (as demonstrated by compounds 9a, 9b, and 11, Figure 3) in the esophageal glands may impact the production of essential proteins (including OvCHT1) that are necessary for molting. ...
Onchocerciasis is an infection caused by the filarial worm Onchocerca volvulus, which can eventually result in blindness. The lack of an effective macrofilaricide and the possible development of ivermectin-resistant strains of O. volvulus necessitate the need for alternative treatment strategies. We have shown that targeting the L3-stage-specific chitinase OvCHT1 impairs the shedding of the filarial cuticle. In our continued efforts to discover OvCHT1 inhibitors, we identified the β-carboline alkaloid scaffolding as a chitinase inhibitor that is capable of penetrating the worm cuticle. Herein, we disclose the rich polypharmacology of the β-carboline class of compounds as an approach to abrogate the molting of the parasite and thus the initiation of infection in the human host.Keywords: Onchocerciasis; β-carbolines; chitinase inhibitor; polypharmacology
... In the horseshoe crab Tachypleus tridentatus, a proteolytic coagulation cascade leads to the conversion of coagulogen into insoluble coagulin polymers, which are in turn stabilized by TGmediated crosslinking with TG substrates including proxin and stablin, resulting in immobilization of invading pathogens at sites of injury10111213. On the other hand, in the nematode parasite Onchocerca volvulus, TG-catalyzed crosslinking is important for the molting of third-stage larvae [14]. TGase activity is also important in hemocyte homeostasis in the hematopoietic tissue of P. leniusculus [15]. ...
Transglutaminase (TG) plays important and diverse roles in mammals, such as blood coagulation and formation of the skin barrier, by catalyzing protein crosslinking. In invertebrates, TG is known to be involved in immobilization of invading pathogens at sites of injury. Here we demonstrate that Drosophila TG is an important enzyme for cuticle morphogenesis. Although TG activity was undetectable before the second instar larval stage, it dramatically increased in the third instar larval stage. RNA interference (RNAi) of the TG gene caused a pupal semi-lethal phenotype and abnormal morphology. Furthermore, TG-RNAi flies showed a significantly shorter life span than their counterparts, and approximately 90% of flies died within 30 days after eclosion. Stage-specific TG-RNAi before the third instar larval stage resulted in cuticle abnormality, but the TG-RNAi after the late pupal stage did not, indicating that TG plays a key role at or before the early pupal stage. Immediately following eclosion, acid-extractable protein from wild-type wings was nearly all converted to non-extractable protein due to wing maturation, whereas several proteins remained acid-extractable in the mature wings of TG-RNAi flies. We identified four proteins--two cuticular chitin-binding proteins, larval serum protein 2, and a putative C-type lectin-as TG substrates. RNAi of their corresponding genes caused a lethal phenotype or cuticle abnormality. Our results indicate that TG-dependent protein crosslinking in Drosophila plays a key role in cuticle morphogenesis and sclerotization.
... In principle, the biosynthesis of MLT-10 and the paralogs of MLT-10 may involve several posttranslational modifications, including but not limited to 1) disulfide bond formation, 2) the addition of O-linked glycans, 3) cleavage of dibasic sites in the nonrepetitive region by subtilisin/Kex2like proteases, 4) cross-linking of glutamine and lysine residues by transglutaminase, and 5) the hydroxylation of some proline residues in the repetitive region. These particular modifications occur during the biosynthesis of collagens and other ECM proteins of nematodes (Fetterer and Rhoads, 1990;Lustigman et al., 1995;Thacker and Rose, 2000;Edens et al., 2001;Page et al., 2006). ...
The molting cycle of nematodes involves the periodic synthesis and removal of a collagen-rich exoskeleton, but the underlying molecular mechanisms are not well understood. Here, we describe the mlt-10 gene of Caenorhabditis elegans, which emerged from a genetic screen for molting-defective mutants sensitized by low cholesterol. MLT-10 defines a large family of nematode-specific proteins comprised of DUF644 and tandem P-X(2)-L-(S/T)-P repeats. Conserved nuclear hormone receptors promote expression of the mlt-10 gene in the hypodermis whenever the exoskeleton is remade. Further, a MLT-10::mCherry fusion protein is released from the hypodermis to the surrounding matrices and fluids during molting. The fusion protein is also detected in strands near the surface of animals. Both loss-of-function and gain-of-function mutations of mlt-10 impede the removal of old cuticles. However, the substitution mutation mlt-10(mg364), which disrupts the proline-rich repeats, causes the most severe phenotype. Mutations of mlt-10 are also associated with abnormalities in the exoskeleton and improper development of the epidermis. Thus, mlt-10 encodes a secreted protein involved in three distinct but interconnected aspects of the molting cycle. We propose that the molting cycle of C. elegans involves the dynamic assembly and disassembly of MLT-10 and possibly the paralogs of MLT-10.
... The molting phenotype and morphology was observed under dissecting microscope every 24 h until the seventh day when the experiment was terminated. On day 7 larval viability was assessed visually after the uptake of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, Sigma) and its reduction into the blue formazan derivative (48), as described previously (49). Briefly, after incubation for 18 h at 37°C, 5% CO 2 , in 100 l of 0.1% MTT, larval viability was scored as live when larvae stained blue uniformly along their entire length and dead when they remained unstained. ...
A novel filarial serine protease inhibitor (SPI) from the human parasitic nematode Onchocerca volvulus, Ov-SPI-1, was identified through the analysis of a molting third-stage larvae expressed sequence tag dataset. Subsequent analysis of the expressed sequence tag datasets of O. volvulus and other filariae identified four other members of this family. These proteins are related to the low molecular weight SPIs originally isolated from Ascaris suum where they are believed to protect the parasite from host intestinal proteases. The two Ov-spi transcripts are up-regulated in the molting larvae and adult stages of the development of the parasite. Recombinant Ov-SPI-1 is an active inhibitor of serine proteases, specifically elastase, chymotrypsin, and cathepsin G. Immunolocalization of the Ov-SPI proteins demonstrates that the endogenous proteins are localized to the basal layer of the cuticle of third-stage, molting third-stage, and fourth-stage larvae, the body channels and multivesicular bodies of third-stage larvae and the processed material found between the two cuticles during molting. In O. volvulus adult worms the Ov-SPI proteins are localized to the sperm and to eggshells surrounding the developing embryos. RNA interference targeting the Ov-spi genes resulted in the specific knockdown of the transcript levels of both Ov-spi-1 and Ov-spi-2, a loss of native proteins, and a significant reduction in both molting and viability of third-stage larvae. We suggest the Ov-SPI proteins play a vital role in nematode molting by controlling the activity of an endogenous serine protease(s). The localization data in adults also indicate that these inhibitors may be involved in other processes such as embryogenesis and spermatogenesis.
... Because of its role in cuticle biosynthesis and lack of homology with mammalian transglutaminases, this parasite enzyme represents a target in the development of an effective chemotherapeutic drug (Chandrashekar and Mehta 2000). Adult worms of B. malayi, B. pahangi and O. volvulus contain high levels of transglutaminase activity (Mehta et al. 1990, 1992; Lustigman et al. 1995). Monodansylcadaverine, a pseudosubstrate of this enzyme was found to affect the release of Mf from B. malayi as well as causing a dose dependent decrease in the MTT reduction potential of the worms (Rao et al. 1991). ...
Filarial nematodes infect more than 150 million people worldwide and are responsible for diseases including elephantiasis, river blindness and tropical pulmonary eosinophilia. Antifilarial agents that can kill all the stages in the life cycle of causative filar- iae have yet to be developed. Very little effort has been made towards rational drug design, employing knowledge gained from studies of the biochemistry and physiology of filarial worms and of their interactions with their specific vertebrate hosts. In this review, we highlight the research and development of rational antifilarial agents and we discuss the pitfalls since the dis- covery of diethylcarbamazine, the only drug of choice for controlling filariasis, despite its adverse side effects.
... The presence of transglutaminase in adult female B. malayi and its role in the in utero development of microfilariae was first reported by Mehta et al. (1990). More recently, the presence of TGases in Dirofilaria immitis ( Chandrashekar et al. 1998), Onchocerca volvulus ( Lustigman et al. 1995), Acanthocheilonema viteae ( Rao et al. 1991), Caenorhabditis elegans ( Natsuka et al. 2001), and Plasmodium falciparum ( Adini et al. 2001) has been reported. The inhibitors of TGase enzyme have been found to inhibit the molting of L3 larvae to L4 stage larvae in O. volvulus and D. immitis (Lustigman et al. 1995;Chandrashekar et al. 2002). ...
Prior studies have demonstrated that transglutaminase (TGase) from the human filarial parasite Brugia malayi is critical for the growth and development of the larval stages. In this report, we describe the cloning and partial characterization of a cDNA encoding the B. malayi TGase (BmTGase). Using RT-PCR and RACE-PCR, the cDNA was amplified from adult worm mRNA. BmTGase is 1,881 bp long and codes for a protein with a predicted molecular mass of 54 kDa. Amino acid sequence analysis of BmTGase revealed significant homology to the protein disulfide isomerase (PDI), particularly, to the PDI-related protein ERp60, a PDI isoform found in the lumen of endoplasmic reticulum. The activity of recombinant B. malayi TGase enzyme (rBmTG) was found to be calcium-dependent and could be inhibited by EDTA. ELISA studies showed that approximately 88% of 48 sera from healthy Indian patients living in a bancroftian filariasis endemic area were reactive with rBmTG. In contrast, only 33% of sera from patients with clinical filariasis were reactive to rBmTG. Non-endemic sera were uniformly non-reactive. Additional studies are needed to elucidate the role, if any, of B. malayi TGase in protective immunity to filariasis.
... Onchocerca volvulus (Lustigman et al, 1995), and possibly plays a role in molting, growth, and development of these parasites. Moreover, TGase was also involved in covalent incorporation of host proteins into developing stages of Brugia malayi (Mehta et al., 1996). ...
... Bio chemical evidence suggests that the presence of TGase catalyzed cross linking of y-(glutamyl)isopeptides in the maturation of sheath and cuticle of filarial nematodes (Mehta et al, 1992;Tarcsa et al, 1992;Zahner et al, 1995;Conraths et al., 1997). It is interesting that the mammalian enzyme is quite distinct from the parasite enzyme in substrate specificity, enzyme activity and molecular mass (Mehta et al., 1992;Singh et al, 1995;Lustigman et al, 1995). ...
... In the present study we have shown the ubiquitous nature of this enzyme by identifying its activity in dif ferent stages of strongyle parasites and in adult worms of two other gastrointestinal nematodes of equids. The cytosol preparations from crude extracts of B. malayi and D. immitis and partially purified enzyme prepa rations of parasite-TGase and their specific inhibition of enzyme activity by using various inhibitors clearly suggest the biological activity of this enzyme in cross linking of parasite proteins (Singh & Mehta, 1994;Lustigman et al, 1995;Singh et al., 1995). However, effect of inhibitors on the enzyme activity of purified protein of strongyles is unknown. ...
Transglutaminases (E.C. 2.3.3.13) are a family of Ca(2+)-dependent enzymes that stabilize protein structure by catalyzing the formation of isopeptide bonds. A novel form of transglutaminase has been identified and characterized that seem to play an important role in growth, development, and molting in adult and larval stages of filarial nematodes. The aim of this study was to identify the ubiquitous nature of this enzyme in other nematodes and to measure its significance to larval growth, molting, and development. For this purpose, equine Strongylus spp. were used. Activity of this enzyme was identified in extracts of larvae and adults of Strongylus vulgaris, S. edentatus, Parascaris equorum and Cylicocyclus insigne. The significance of transglutaminase in the early growth and development of Strongylus vulgaris, S. edentatus and S. equinus was tested by adding specific inhibitors, monodansylcadaverine (MDC) or cystamine (CS), to in vitro cultures of third (L3) and fourth stage larvae (L4). The viability, molting and growth of these nematode species were affected by both inhibitors. Cystamine promoted abnormal development of Strongylus edentatus L3, resulting in an aberrant expansion of the anterior end. Addition of these inhibitors to cultures of L4 also reduced growth of the three species. The results indicated that transglutaminase is present in a wide array of nematode parasites and may be important in growth and development of their larval stages.
In the past two decades, there has been an upsurge of interest in transglutaminase (TGase) research due to their immense value in food applications to improve the quality as well as functional and nutritional attributes of food. Besides, TGases have been involved in new biomaterial development and shown to have potential in various biomedical applications. Presently, TGases from microbial sources (and some animal sources) are the main forms of the enzyme used in industrial applications. Nonetheless, there are disadvantages with the commercial TGases currently in use for food processing, such as the low activity, low yield, high cost, consumer aversions on their safety, and difficult in activity recovery, among others. Fish and shellfish TGases are promising alternatives for use in food industries due to their cheap sources, high yield and special characteristics such as cold activity and thermal-lability. This review presents at the onset, the catalytic mechanism of TGase based on updated research; compares the enzymatic properties of fish/shellfish TGases with their animal, plant and microbial counterparts; summarizes the unique properties of fish/shellfish TGases related with food usage; and discusses the current and potential applications of fish/shellfish TGases in foods.
An attempt has been made to identify and characterize a putative chemotherapeutic target antigen for human lymphatic filariasis by recombinant DNA techniques. Identification of transglutaminase (TGA), an enzyme vital for the growth and survival of the parasites, has opened a new drug target for developing potent therapeutic agents against the parasites. TGA gene from Brugia malayi adult female parasite (BmTGA) has been subcloned, expressed and purified as a 47 kDa fusion protein with N-terminal histidine tag. Since BmTGA lacks homology to mammalian TGAs, it is a promising drug target for developing chemotherapeutic agent and candidate vaccine against human lymphatic filariasis.
