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A study of selected Plasmodium yoelii messenger RNAs during hepatocyte infection
M Nivez1, A Achbarou, J D Bienvenu
1INSERM, Unité U511, Immunobiologie Cellulaire et Moléculaire des Infections Parasitaires, CHU Pitié-Salpétrière, 91 Boulevard de l'Hôpital, Paris 75013, France.
Abstract:
We investigated the expression of several mRNAs in exoerythrocytic and erythrocytic stages of Plasmodium yoelii in infected mice, focusing our attention on genes thought to be involved in signal transduction (like pypka and pymap-1, encoding homologues of cAMP-dependent and mitogen-activated protein kinases, respectively) and cell cycle progression (those encoding the cdc2-related kinases Pycrk-1, Pycrk-3 and Pymrk). Messengers coding for enzymes involved in general processes such as DNA replication and RNA transcription (both subunits of the ribonucleotide reductase (Pyrnr1, Pyrnr2) and RNA polymerase II) as well as a messenger coding for Pys21, a sexual stage-specific protein, were also investigated. Total RNA was prepared from livers of infected mice at different times post sporozoite inoculation. In contrast to the pys21 transcript, which was observed only in infected erythrocytes, all messenger species could be detected in the liver by RT-PCR, peaking at 43 h post infection, a time when parasite burden was maximum, and decreasing markedly thereafter to become hardly visible at 168 h. Some transcripts (pypka, pymap-1, pyrnr1 and pyrnr2) could be detected 12 h after infection, while others (pymrk and pyrnapolII) did not become detectable until 24 h. In addition, we characterised all these messengers by Northern blot of total RNAs extracted from infected erythrocytes. Taken together, these data suggest that a similar set of regulatory genes is expressed during both exoerythrocytic and erythrocytic schizogony.
Insights
This study investigated Plasmodium yoelii gene expression during infection. Key regulatory genes involved in signal transduction and cell cycle progression are expressed in both exoerythrocytic and erythrocytic stages.
Area of Science:
- Malariology
- Molecular Parasitology
- Gene Expression Analysis
Background:
- The Plasmodium yoelii parasite undergoes complex life cycle stages, including exoerythrocytic and erythrocytic schizogony.
- Understanding gene expression patterns is crucial for identifying potential drug targets and comprehending parasite development.
Purpose of the Study:
- To investigate the expression profiles of specific mRNAs in Plasmodium yoelii during its exoerythrocytic and erythrocytic stages in infected mice.
- To compare the expression of genes involved in signal transduction, cell cycle progression, DNA replication, RNA transcription, and sexual stage development.
Main Methods:
- Quantitative analysis of messenger RNA (mRNA) expression using Reverse Transcription Polymerase Chain Reaction (RT-PCR) on RNA from infected mouse livers.
- Northern blot analysis was performed on total RNA extracted from infected erythrocytes.
- Time-course analysis of gene expression post-sporozoite inoculation.
Main Results:
- All investigated messenger species, except for the sexual stage-specific Pys21 transcript, were detected in the liver, peaking at 43 hours post-infection.
- Expression of some transcripts (pypka, pymap-1, pyrnr1, pyrnr2) was detectable as early as 12 hours post-infection, while others (pymrk, pyrnapolII) appeared at 24 hours.
- Northern blot analysis confirmed the presence of these messengers in infected erythrocytes.
Conclusions:
- A similar set of regulatory genes is expressed during both the exoerythrocytic and erythrocytic schizogony stages of Plasmodium yoelii.
- These findings provide insights into the molecular mechanisms governing parasite development and suggest conserved regulatory pathways across different life cycle stages.