Leishmania mexicana metacaspase is a negative regulator of amastigote proliferation in mammalian cells.

ABSTRACT: Metacaspases (MCAs) are caspase family cysteine peptidases that have been implicated in cell death processes in plants, fungi and protozoa. MCAs have also been suggested to be involved in cell cycle control, differentiation and clearance of aggregates; they are virulence factors. Dissecting the function of MCAs has been complicated by the presence in many organisms of multiple MCA genes or limitations on genetic manipulation. We describe here the creation of a MCA gene-deletion mutant (?mca) in the protozoan parasite Leishmania mexicana, which has allowed us to dissect the role of the parasite's single MCA gene in cell growth and cell death. ?mca parasites are viable as promastigotes, and differentiate normally to the amastigote form both in in vitro macrophages infection and in mice. ?mca promastigotes respond to cell death inducers such as the drug miltefosine and H(2)O(2) similarly to wild-type (WT) promastigotes, suggesting that MCAs do not have a caspase-like role in execution of L. mexicana cell death. ?mca amastigotes replicated significantly faster than WT amastigotes in macrophages and in mice, but not as axenic culture in vitro. We propose that the Leishmania MCA acts as a negative regulator of amastigote proliferation, thereby acting to balance cell growth and cell death.

SUBMITTER: Castanys-Munoz E 

PROVIDER: S-EPMC3461358 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature