The role of Trypanosoma brucei MRPA in melarsoprol susceptibility

Alibu, Vincent P.; Richter, Christina; Voncken, Frank; Marti, Gabriela; Shahi, Sanjay; Renggli, Christina Kunz; Seebeck, Thomas; Brun, Reto; Clayton, Christine

doi:10.1016/j.molbiopara.2005.10.016

Cited by 34 publications

(19 citation statements)

References 29 publications

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“…However, in studies with the P-glycoprotein inhibitor verapamil, no evidence could be found for the involvement of such transporters in multidrug resistance in T. brucei brucei, either in vitro or in vivo (Kaminsky and Zweygarth, 1991). Experimental overexpression of the T. brucei brucei ABC transporter TbMRPA led to substantial melarsoprol resistance in vitro (Shahi et al, 2002) but not in vivo, and TbMRPA overexpression was not observed in melarsoprol-resistant clinical isolates from a number of patients with sleeping sickness (Alibu et al, 2006). Thus, although resistance based on target modifications or active efflux cannot be excluded, the available information is consistent with changes to drug entry being the cause of arsenical and diamidine resistance in African trypanosomes.…”

Section: Discussionmentioning

confidence: 99%

“…Arsenical resistance attributed to loss of TbAT1/P2 and overexpression of TbMRPA were shown to be additive (Lü scher et al, 2006). However, TbMRPA overexpression did not lead to arsenical resistance in vivo, and TbMRPA overexpression could not be demonstrated in melarsoprol-resistant trypanosome isolates from patients with sleeping sickness (Alibu et al, 2006).…”

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confidence: 95%

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Loss of the High-Affinity Pentamidine Transporter Is Responsible for High Levels of Cross-Resistance between Arsenical and Diamidine Drugs in African Trypanosomes

Bridges¹,

Gould²,

Nerima³

et al. 2007

Mol Pharmacol

118

242

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Treatment of many infectious diseases is under threat from drug resistance. Understanding the mechanisms of resistance is as high a priority as the development of new drugs. We have investigated the basis for cross-resistance between the diamidine and melaminophenyl arsenical classes of drugs in African trypanosomes. We induced high levels of pentamidine resistance in a line without the tbat1 gene that encodes the P2 transporter previously implicated in drug uptake. We isolated independent clones that displayed very considerable crossresistance with melarsen oxide but not phenylarsine oxide and reduced uptake of [ 3 H]pentamidine. In particular, the highaffinity pentamidine transport (HAPT1) activity was absent in the pentamidine-adapted lines, whereas the low affinity pentamidine transport (LAPT1) activity was unchanged. The parental tbat1 Ϫ/Ϫ line was sensitive to lysis by melarsen oxide, and this process was inhibited by low concentrations of pentamidine, indicating the involvement of HAPT1. This pentamidine-inhibitable lysis was absent in the adapted line KO-B48. Likewise, uptake of the fluorescent diamidine 4Ј,6-diamidino-2-phenylindole dihydrochloride was much delayed in live KO-B48 cells and insensitive to competition with up to 10 M pentamidine. No overexpression of the Trypanosoma brucei brucei ATPbinding cassette transporter TbMRPA could be detected in KO-B48. We also show that a laboratory line of Trypanosoma brucei gambiense, adapted to high levels of resistance for the melaminophenyl arsenical drug melarsamine hydrochloride (Cymelarsan), had similarly lost TbAT1 and HAPT1 activity while retaining LAPT1 activity. It seems therefore that selection for resistance to either pentamidine or arsenical drugs can result in a similar phenotype of reduced drug accumulation, explaining the occurrence of cross-resistance.Trypanosoma brucei subspp. are protozoan parasites that cause human African trypanosomiasis (i.e., sleeping sickness) and the corresponding veterinary condition in livestock. Treatment of both the human and livestock diseases depends on a very small set of mostly very old drugs. The first-line treatment for the late stage of both West African and East African human African trypanosomiasis is melarsoprol, an organoarsenic compound of the melaminophenyl arsenical class, introduced in 1949 (Jannin and Cattand, 2004). A similar but water-soluble melaminophenyl arsenical, melarsamine hydrochloride (Cymelarsan), is increasingly used for animal trypanosomiasis. Early-stage West African sleeping sickness is routinely treated with the diamidine drug pentamidine, introduced in 1937 (Jannin and Cattand, 2004). The corresponding widely used veterinary diamidine is diminazene aceturate (Berenil). The only new trypanocide to be developed in recent decades, DB75, is also a diamidine and currently in clinical trials as an orally available prodrug.It has been known for decades that cross-resistance between melaminophenyl arsenicals and diamidine drugs sometimes occurs (Fulton and Grant, 1955;Williamson a...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 95%

Loss of the High-Affinity Pentamidine Transporter Is Responsible for High Levels of Cross-Resistance between Arsenical and Diamidine Drugs in African Trypanosomes

Bridges¹,

Gould²,

Nerima³

et al. 2007

Mol Pharmacol

118

242

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“…Besides loss of import to the parasite, increased export of the drug also can be responsible for the drug resistance. In this aspect, over expression of one exporter, TbMRPA ( T. brucei multidrug-resistance associated protein) caused 10-fold resistance to the melarsoprol in vitro [290, 291] but such over expression in patients with treatment failure with melarsoprol has not been reported yet. Similarly, over expression of a gene TeDR40 has been shown to correlate with Berenil resistance observed in T. evansi [292].…”

Section: Current and Alternative Control Strategies For Trypanosommentioning

confidence: 99%

Immunobiology of African Trypanosomes: Need of Alternative Interventions

Baral

2010

Journal of Biomedicine and Biotechnology

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Trypanosomiasis is one of the major parasitic diseases for which control is still far from reality. The vaccination approaches by using dominant surface proteins have not been successful, mainly due to antigenic variation of the parasite surface coat. On the other hand, the chemotherapeutic drugs in current use for the treatment of this disease are toxic and problems of resistance are increasing (see Kennedy (2004) and Legros et al. (2002)). Therefore, alternative approaches in both treatment and vaccination against trypanosomiasis are needed at this time. To be able to design and develop such alternatives, the biology of this parasite and the host response against the pathogen need to be studied. These two aspects of this disease with few examples of alternative approaches are discussed here.

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“…Trypanothione has also been implicated in the mode of action as well as the mechanism of resistance of antimonial drugs in Leishmania spp. (Mukhopadhyay et al ., 1996; Wyllie et al ., 2004; Croft et al ., 2006) and in defence against chemical and oxidant stress induced by arsenicals and nifurtimox in T. brucei (Fairlamb et al ., 1989; Ariyanayagam et al ., 2005; Alibu et al ., 2006). Therefore, in an attempt to exploit this essential and unique metabolite, T[SH] 2 ‐dependent and biosynthetic enzymes have become a major focus for drug discovery.…”

Section: Introductionmentioning

confidence: 99%

Dissecting the essentiality of the bifunctional trypanothione synthetase‐amidase in Trypanosoma brucei using chemical and genetic methods

Wyllie

Oza

Patterson

et al. 2009

Molecular Microbiology

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The bifunctional trypanothione synthetase-amidase (TRYS) comprises two structurally distinct catalytic domains for synthesis and hydrolysis of trypanothione (N1,N8-bis(glutathionyl)spermidine). This unique dithiol plays a pivotal role in thiol-redox homeostasis and in defence against chemical and oxidative stress in trypanosomatids. A tetracycline-dependent conditional double knockout of TRYS (cDKO) was generated in bloodstream Trypanosoma brucei. Culture of cDKO parasites without tetracycline induction resulted in loss of trypanothione and accumulation of glutathione, followed by growth inhibition and cell lysis after 6 days. In the absence of inducer, cDKO cells were unable to infect mice, confirming that this enzyme is essential for virulence in vivo as well as in vitro. To establish whether both enzymatic functions were essential, an amidase-dead mutant cDKO line was generated. In the presence of inducer, this line showed decreased growth in vitro and decreased virulence in vivo, indicating that the amidase function is not absolutely required for viability. The druggability of TRYS was assessed using a potent small molecule inhibitor developed in our laboratory. Growth inhibition correlated in rank order cDKO, single KO, wild-type and overexpressing lines and produced the predicted biochemical phenotype. The synthetase function of TRYS is thus unequivocally validated as a drug target by both chemical and genetic methods.

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The role of Trypanosoma brucei MRPA in melarsoprol susceptibility

Cited by 34 publications

References 29 publications

Loss of the High-Affinity Pentamidine Transporter Is Responsible for High Levels of Cross-Resistance between Arsenical and Diamidine Drugs in African Trypanosomes

Loss of the High-Affinity Pentamidine Transporter Is Responsible for High Levels of Cross-Resistance between Arsenical and Diamidine Drugs in African Trypanosomes

Immunobiology of African Trypanosomes: Need of Alternative Interventions

Dissecting the essentiality of the bifunctional trypanothione synthetase‐amidase in Trypanosoma brucei using chemical and genetic methods

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