Cathepsin B-like cysteine proteinase-deficient mutants of Leishmania mexicana

Bart, Geneviève; Frame, Mhairi; Carter, Roderick; Coombs, Graham H.; Mottram, Jeremy C.

doi:10.1016/s0166-6851(97)00072-8

Cited by 65 publications

(38 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, the reduction in parasite survival was not completely affected, which may be attributed to the redundant activity of other proteases like cathepsin L. Similar results were obtained in case of L. mexicana cpc (cathepsin B) null mutants, wherein the null mutants infected fewer peritoneal exudate cells than did the wild type parasites, confirming that cathepsin B does indeed play some part in the mammalian infective stages of the parasite (29). Results from this study, as well as that of others (6,29), show that cathepsin B plays a role in enabling Leishmania to live within the macrophages. On the other hand, studies on cathepsin L-like cysteine proteases (cpb) null mutants have implicated cpb genes in being a virulence factor (30).…”

Section: Discussionsupporting

confidence: 72%

Functional Analysis of Cathepsin B-like Cysteine Proteases fromLeishmania donovani Complex

Somanna¹,

Mundodi²,

Gedamu

2002

Journal of Biological Chemistry

View full text Add to dashboard Cite

Cathepsin B-like genes from Leishmania donovani and Leishmania chagasi have been isolated and characterized. It is a single gene, which is constitutively expressed in all the life cycle stages of the parasite. Studies using cathepsin B-specific inhibitor treatment suggested that cathepsin B does not seem to play a role in the promastigote stages of the parasite, however it aids in the parasite survival within the host macrophages. Antisense mRNA inhibition of cathepsin B gene also revealed that it plays an important role in the parasite survival within the host macrophages. Furthermore, for the first time, we have shown that Leishmania whole cell lysates as well as the recombinant cathepsin B protein cleaved human recombinant latent transforming growth factor (TGF)-␤1 into a mature peptide releasing the latency associated protein, in a cell-free incubation system. Mink lung epithelial cell growth inhibition assay revealed that the cleaved TGF-␤1 was biologically active, suggesting that Leishmania cathepsin B can cleave latent TGF-␤1 into mature and active form. These results suggest that cathepsin B plays an important role in Leishmania survival within the host macrophages by activating latent TGF-␤1.

show abstract

Section: Discussionsupporting

confidence: 72%

Functional Analysis of Cathepsin B-like Cysteine Proteases fromLeishmania donovani Complex

Somanna¹,

Mundodi²,

Gedamu

2002

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…1A) were amplified by PCR, using primers that incorporated restriction sites suitable for subsequent insertion into the polylinker regions flanking the PAC gene in pX63PAC. The gene deletion construct for nourseothricin selection (LmGTKOSAT) was generated by removing the PAC coding region from LmGTKOPAC and replacing it with a fragment containing the SAT coding region from pCPC-SAT (19). Plasmid DNA for each construct was digested with three restriction enzymes to destroy the plasmid backbone, and the linear gene deletion constructs were gel purified by using QIAEX columns (Qiagen, Valencia, CA).…”

Section: Methodsmentioning

confidence: 99%

Genetic characterization of glucose transporter function inLeishmania mexicana

Burchmore

Rodriguez‐Contreras

McBride

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

127

165

View full text Add to dashboard Cite

Both insect and mammalian life cycle stages of Leishmania mexicana take up glucose and express all three isoforms encoded by the LmGT glucose transporter gene family. To evaluate glucose transporter function in intact parasites, a null mutant line has been created by targeted disruption of the LmGT locus that encompasses the LmGT1, LmGT2, and LmGT3 genes. This Δlmgt null mutant exhibited no detectable glucose transport activity. The growth rate of the Δlmgt knockout in the promastigote stage was reduced to a rate comparable with that of WT cells grown in the absence of glucose. Δlmgt cells also exhibited dramatically reduced infectivity to macrophages, demonstrating that expression of LmGT isoforms is essential for viability of amastigotes. Furthermore, WT L. mexicana were not able to grow as axenic culture form amastigotes if glucose was withdrawn from the medium, implying that glucose is an essential nutrient in this life cycle stage. Expression of either LmGT2 or LmGT3, but not of LmGT1, in Δlmgt null mutants significantly restored growth as promastigotes, but only LmGT3 expression substantially rescued amastigote growth in macrophages. Subcellular localization of the three isoforms was investigated in Δlmgt cells expressing individual LmGT isoforms. Using anti-LmGT antiserum and GFP-tagged LmGT fusion proteins, LmGT2 and LmGT3 were localized to the cell body, whereas LmGT1 was localized specifically to the flagellum. These results establish that each glucose transporter isoform has distinct biological functions in the parasite

show abstract

“…Cathepsins L and B have been cloned from L. mexicana, L. donovani, L. major, and L. chagasi (20,(52)(53)(54). Studies of null mutants have documented a role for each cathepsin in L. mexicana virulence (53,(55)(56)(57)(58). Treatment of infected mice with specific inhibitors suggests that cathepsin B of the parasite (or host) promotes disease progression (23,27,59).…”

Section: Discussionmentioning

confidence: 99%

Activation of TGF-β by Leishmania chagasi: Importance for Parasite Survival in Macrophages

Gantt¹,

Schultz‐Cherry

Rodríguez

et al. 2003

The Journal of Immunology

159

104

View full text Add to dashboard Cite

TGF-β is a potent regulatory cytokine that suppresses expression of inducible NO synthase and IFN-γ, and suppresses Th1 and Th2 cell development. We examined whether functionally active TGF-β is present in the local environment surrounding the invading protozoan Leishmania chagasi. Our prior data showed that TGF-β levels are significantly increased in L. chagasi-infected mice. In the current study, we found TGF-β was also abundant in bone marrows of humans with acute visceral leishmaniasis but not in those of uninfected controls. Furthermore, L. chagasi infection caused an increase in biologically active TGF-β in human macrophage cultures without changing the total TGF-β. Therefore, we investigated the means through which leishmania could augment activated but not total TGF-β. Incubation of latent TGF-β with Leishmania sp. promastigotes caused active TGF-β to be released from the latent complex. In contrast, the nonpathogenic protozoan Crithidia fasciculata could not activate TGF-β. TGF-β activation by leishmania was prevented by inhibitors of cysteine proteases and by the specific cathepsin B inhibitor CA074. Physiologic concentrations of TGF-β inhibited killing of intracellular L. chagasi in macrophages, although the phagocytosis-induced respiratory burst remained intact. In contrast, supraphysiologic concentrations of TGF-β had no effect on parasite survival. We hypothesize that the combined effect of abundant TGF-β stores at extracellular sites during infection, and the ability of the parasite to activate TGF-β in its local environment, leads to high levels of active TGF-β in the vicinity of the infected macrophage. Locally activated TGF-β could, in turn, enhance parasite survival through its effects on innate and adaptive immune responses.

show abstract

Cathepsin B-like cysteine proteinase-deficient mutants of Leishmania mexicana

Cited by 65 publications

References 28 publications

Functional Analysis of Cathepsin B-like Cysteine Proteases fromLeishmania donovani Complex

Functional Analysis of Cathepsin B-like Cysteine Proteases fromLeishmania donovani Complex

Genetic characterization of glucose transporter function inLeishmania mexicana

Activation of TGF-β by Leishmania chagasi: Importance for Parasite Survival in Macrophages

Contact Info

Product

Resources

About