Project description:Epigenetic mechanisms have been poorly understood in Plasmodium falciparum, the causative agent of malaria. To elucidate stage specific epigenetic regulations in P. falciparum, we performed genome-wide mapping of various histone modifications, nucleosomes and RNA Polymerase II. Our comprehensive analysis suggest that transcription initiation and elongation are distinct in Plasmodium. In this study, by analyzing histone modifications, nucleosome occupancy and RNA Polymerase II (Pol II) at three different IEC developmental stages of Plasmodium; ring, trophozoite and schizont, we tried to unravel the epigenetic mechanism associated with gene regulation. Examination of H3K27me3, H3K4me3, H3K9me3, H3K14ac, H3K4me1, H3K79me3, H3K27ac, H3K4me2, H3K9ac, H4ac, RNA Pol II and Histone H3 at three different stages of Plasmodium falciparum
Project description:Epigenetic mechanisms have been poorly understood in Plasmodium falciparum, the causative agent of malaria. To elucidate stage specific epigenetic regulations in P. falciparum, we performed genome-wide mapping of various histone modifications, nucleosomes and RNA Polymerase II. Our comprehensive analysis suggest that transcription initiation and elongation are distinct in Plasmodium. In this study, by analyzing histone modifications, nucleosome occupancy and RNA Polymerase II (Pol II) at three different IEC developmental stages of Plasmodium; ring, trophozoite and schizont, we tried to unravel the epigenetic mechanism associated with gene regulation.
Project description:Gene expression in malaria parasites is subject to various layers of regulation, including histone post-translational modifications (PTMs). Gene regulatory mechanisms have been extensively studied during the main developmental stages of Plasmodium parasites inside erythrocytes, from the ring stage following invasion to the schizont stage leading up to egress. However, gene regulation in merozoites that mediate the transition from one host cell to the next is an understudied area of parasite biology. Here, we sought to characterize gene expression and the corresponding histone PTM landscape during this stage of the parasite lifecycle through RNA-seq and ChIP-seq on P. falciparum blood stage schizonts, merozoites, and rings, as well as P. berghei liver stage merozoites. In both hepatic and erythrocytic merozoites, we identified a subset of genes with a unique histone PTM profile characterized by depletion of H3K4me3 in their promoter regions. These genes were upregulated in merozoites and rings, had roles in protein export, translation, and host cell remodeling, and shared a DNA motif. These results indicate that similar regulatory mechanisms may underlie merozoite formation in the liver and blood stages. We also observed that H3K4me2 was deposited in gene bodies of gene families encoding variant surface antigens in erythrocytic merozoites, which may facilitate switching of gene expression between different members of these families. Finally, H3K18me and H2K27me were uncoupled from gene expression and were enriched around the centromeres in erythrocytic merozoites, suggesting roles in the maintenance of chromosomal organization during schizogony. Together, our results demonstrate that extensive changes in gene expression and histone landscape occur during the schizont-to-ring transition to facilitate productive erythrocyte infection. The dynamic remodeling of the transcriptional program in hepatic and erythrocytic merozoites makes this stage attractive as a target for novel anti-malarial approaches that may have activity against both the liver and blood stages.
Project description:Gene expression in malaria parasites is subject to various layers of regulation, including histone post-translational modifications (PTMs). Gene regulatory mechanisms have been extensively studied during the main developmental stages of Plasmodium parasites inside erythrocytes, from the ring stage following invasion to the schizont stage leading up to egress. However, gene regulation in merozoites that mediate the transition from one host cell to the next is an understudied area of parasite biology. Here, we sought to characterize gene expression and the corresponding histone PTM landscape during this stage of the parasite lifecycle through RNA-seq and ChIP-seq on P. falciparum blood stage schizonts, merozoites, and rings, as well as P. berghei liver stage merozoites. In both hepatic and erythrocytic merozoites, we identified a subset of genes with a unique histone PTM profile characterized by depletion of H3K4me3 in their promoter regions. These genes were upregulated in merozoites and rings, had roles in protein export, translation, and host cell remodeling, and shared a DNA motif. These results indicate that similar regulatory mechanisms may underlie merozoite formation in the liver and blood stages. We also observed that H3K4me2 was deposited in gene bodies of gene families encoding variant surface antigens in erythrocytic merozoites, which may facilitate switching of gene expression between different members of these families. Finally, H3K18me and H2K27me were uncoupled from gene expression and were enriched around the centromeres in erythrocytic merozoites, suggesting roles in the maintenance of chromosomal organization during schizogony. Together, our results demonstrate that extensive changes in gene expression and histone landscape occur during the schizont-to-ring transition to facilitate productive erythrocyte infection. The dynamic remodeling of the transcriptional program in hepatic and erythrocytic merozoites makes this stage attractive as a target for novel anti-malarial approaches that may have activity against both the liver and blood stages.
Project description:We identified unconventional histone lysine trimethylation mark in the nucleosome core at H3K64 position in human malaria parasite Plasmodium falciparum. Global ChIP analysis was performed using anti-H3K64me3 specific antibody for three major blood stages, i.e. ring, trophozoite and schizont stages to identify the genomic position of the H3K64me3. The sheared chromatin was prepared from highly synchronous P. falciparum culture and subjected for ChIP followed by library preparation from the ChIP DNA and were subjected to sequencing using the HiSeq Illumina platform. H3K64me3 binding sites were determined after sequence alignment and normalization with input sequence. Interestingly, there was a significant reduction in the number of peaks on different chromosomes during multinucleated schizont stage as compared to ring and trophozoite stage. Collectively, this is first study to show that H3K64me3 function as repressor methyl mark during ring and trophozoite stages to regulate the expression of schizont specific export family of proteins in P. falciparum.
Project description:The parasite Plasmodium falciparum is responsible for severe malaria, which is still one of the major causes of death in developing countries. To provide a new RNA-seq reference dataset for its blood-stage transcriptome according to current guidelines and best practices, we performed a time course experiment with three independent biological replicates of synchronized P. falciparum 3D7 cells, that were cultivated at a haematocrit of 5% in human O+ erythrocytes. RNA-seq samples were taken at 8 developmental stages including young ring stage (8 hpi), late ring stage/early trophozoite (16 hpi), mid-age trophozoite (24 hpi), late trophozoite (32 hpi), early schizont (40 hpi), schizont (44 hpi), late schizont (48 hpi) and purified merozoites (0 hpi). Red blood cell pellets were lysed with Trizol and total RNA was purified using column-based purification (PureLink RNA Kit) including DNase treatment on the column and controlling for absence of genomic DNA contamination using qPCR. Whole blood total RNA samples were depleted of human globin mRNA using magnetic bead isolation technology (GLOBINclear kit). After RNA sample quality control and optimized cDNA libraries preparation for AT-biased genomes for Illumina sequencing, RNA-seq was performed at BGI Genomics (Shenzhen, China) on HiSeq 4000 to generate 100 bp paired-end sequencing reads.