title: Disruption of cellular homeostasis induces organelle stress and triggers apoptosis like cell-death pathways in malaria parasite.
abstract: A regulated protein turnover machinery in the cell is essential for effective cellular homeostasis; any interference with this system induces cellular stress and alters the normal functioning of proteins important for cell survival. In this study, we show that persistent cellular stress and organelle dysfunction because of disruption of cellular homeostasis in human malaria parasite Plasmodium falciparum, leads to apoptosis-like cell death. Quantitative global proteomic analysis of the stressed parasites before onset of cell death, showed upregulation of a number of proteins involved in cellular homeostasis; protein network analyses identified upregulated metabolic pathways that may be associated with stress tolerance and pro-survival mechanism. However, persistent stress on parasites cause structural abnormalities in endoplasmic reticulum and mitochondria, subsequently a cascade of reactions are initiated in parasites including rise in cytosolic calcium levels, loss of mitochondrial membrane potential and activation of VAD-FMK-binding proteases. We further show that activation of VAD-FMK-binding proteases in the parasites leads to degradation of phylogenetically conserved protein, TSN (Tudor staphylococcal nuclease), a known target of metacaspases, as well as degradation of other components of spliceosomal complex. Loss of spliceosomal machinery impairs the mRNA splicing, leading to accumulation of unprocessed RNAs in the parasite and thus dysregulate vital cellular functions, which in turn leads to execution of apoptosis-like cell death. Our results establish one of the possible mechanisms of instigation of cell death by organelle stress in Plasmodium.
authors.affiliation: Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Rathore
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
authors.forename: G
authors.initials: G
authors.lastname: Datta
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
authors.forename: I
authors.initials: I
authors.lastname: Kaur
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
authors.forename: P
authors.initials: P
authors.lastname: Malhotra
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
authors.forename: A
authors.initials: A
authors.lastname: Mohmmed
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D002460:Cell Line; D057056:Cysteine Proteases / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000473:pathology; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D016778:Malaria, Falciparum / Q000188:drug therapy; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism; D010963:Plasmodium falciparum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors / Q000494:pharmacology; D015800:Protozoan Proteins / Q000378:metabolism; D012326:RNA Splicing / Q000187:drug effects / Q000235:genetics*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D007976:Leupeptins; D061988:Proteasome Inhibitors; D015800:Protozoan Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D057056:Cysteine Proteases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde