Leishmania sp. protozoa are exposed to diverse environments as they cycle between an insect vector and a mammalian host. Within these diverse environments the parasites exist in different developmental forms, uniquely adapted for survival in their specific host. Part of their survival mechanisms involves the developmental expression of surface antigens. We have found that the amount of the major surface protease (gp63) in Leishmania donovani chagasi (Ldc) promastigotes increases 10-fold as they develop from a less infectious form during early logarithmic growth to a more virulent form during stationary phase of in vitro cultivation. This process probably mimics the natural development of promastigotes to an infectious state in the gut of their sandfly vector. The increase in gp63 is accompanied by differential expression of three RNA transcripts from different gp63 gene classes, distinguishable by unique 3' untranslated regions (UTRs) (Manuscripts 1 and 2, Appendix). The goal of the proposed work is to delineate the molecular mechanisms directing the expression of the different gp63 genes during the in vitro developments of Ldc promastigotes. Gp63 is encoded by a family of tandemly repeated genes on a single chromosome. We will begin our studies by clarifying the genomic organization of the three gp63 gene classes in Ldc, and identifying flanking and intercistronic sequences that are potential regulatory elements. We will examine the transcription rates of the three gp63 gene classes and the potential contribution of the unique 3'UTRs to the steady state levels of the gp63 RNAs at different growth stages of promastigote cultures. We will explore the roles of DNA- and RNA-binding proteins in regulating the rates of gp63 gene transcription and gp63 RNA degradation. The functional roles of the protein products of individual gp63 genes will be addressed by replacement, insertion and disruption of these genes in cloned promastigotes. Gp63 mutants will be assayed for intracellular survival, virulence and attachment to macrophage receptors. Finally, we will determine if protein is expressed from each of the unique gp63 RNAs. We expect that the collective molecular mechanisms that we find to regulate the expression of the gp63 gene family will be applicable to a general understanding of developmental regulation in Trypanosomatid protozoa.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI032135-02
Application #
3147184
Study Section
Tropical Medicine and Parasitology Study Section (TMP)
Project Start
1992-02-01
Project End
1997-01-31
Budget Start
1993-02-01
Budget End
1994-01-31
Support Year
2
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Medicine
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Herrera, Alfa; Kulhankova, Katarina; Sonkar, Vijay K et al. (2017) Staphylococcal ?-Toxin Modulates Human Aortic Endothelial Cell and Platelet Function through Sphingomyelinase and Biofilm Ligase Activities. MBio 8:
Yao, Chaoqun; Gaur Dixit, Upasna; Barker, Jason H et al. (2013) Attenuation of Leishmania infantum chagasi metacyclic promastigotes by sterol depletion. Infect Immun 81:2507-17
Graff, Joel W; Powers, Linda S; Dickson, Anne M et al. (2012) Cigarette smoking decreases global microRNA expression in human alveolar macrophages. PLoS One 7:e44066
Hsiao, Chia-Hung Christine; Ueno, Norikiyo; Shao, Jian Q et al. (2011) The effects of macrophage source on the mechanism of phagocytosis and intracellular survival of Leishmania. Microbes Infect 13:1033-44
Yao, Chaoqun; Li, Yalan; Donelson, John E et al. (2010) Proteomic examination of Leishmania chagasi plasma membrane proteins: Contrast between avirulent and virulent (metacyclic) parasite forms. Proteomics Clin Appl 4:4-16
Yao, Chaoqun; Chen, Yani; Sudan, Bayan et al. (2008) Leishmania chagasi: homogenous metacyclic promastigotes isolated by buoyant density are highly virulent in a mouse model. Exp Parasitol 118:129-33
Hsiao, Chia-Hung Christine; Yao, Chaoqun; Storlie, Patricia et al. (2008) The major surface protease (MSP or GP63) in the intracellular amastigote stage of Leishmania chagasi. Mol Biochem Parasitol 157:148-59
Yao, Chaoqun; Luo, Jiwen; Hsiao, Chia-Hung Christine et al. (2007) Leishmania chagasi: a tetracycline-inducible cell line driven by T7 RNA polymerase. Exp Parasitol 116:205-13
Yao, Chaoqun; Donelson, John E; Wilson, Mary E (2007) Internal and surface-localized major surface proteases of Leishmania spp. and their differential release from promastigotes. Eukaryot Cell 6:1905-12
Aleixo, J A; Nascimento, E T; Monteiro, G R et al. (2006) Atypical American visceral leishmaniasis caused by disseminated Leishmania amazonensis infection presenting with hepatitis and adenopathy. Trans R Soc Trop Med Hyg 100:79-82

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