Phosphorylation of Eukaryotic Initiation Factor-2α during Stress and Encystation in Entamoeba Species
| Autor: | Brenda H. Welter, Holland M. Hendrick, Matthew A. Hapstack, William J. Sullivan, Lesly A. Temesvari, Steven E. Sykes |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Parasite Encystment Protein Expression Eukaryotic Initiation Factor-2 Biochemistry Polymerase Chain Reaction Serine Entamoeba Antibiotics Eukaryotic initiation factor Protein biosynthesis Medicine and Health Sciences Biology (General) Post-Translational Modification Phosphorylation 2. Zero hunger Protozoans biology Chemistry Antimicrobials Organic Compounds Monosaccharides Drugs Cell biology Tetracyclines Physical Sciences Cellular Structures and Organelles Research Article QH301-705.5 030106 microbiology Immunology Blotting Western Carbohydrates Research and Analysis Methods Microbiology Entamoeba Histolytica 03 medical and health sciences Entamoeba histolytica Eukaryotic translation Stress Physiological Virology Polysome Microbial Control Parasite Groups Genetics Gene Expression and Vector Techniques Trophozoites Molecular Biology Techniques Molecular Biology Pharmacology Molecular Biology Assays and Analysis Techniques Organisms Genetically Modified Organic Chemistry Wild type Organisms Chemical Compounds Biology and Life Sciences Proteins Cell Biology RC581-607 biology.organism_classification Parasitic Protozoans Oxidative Stress 030104 developmental biology Glucose Polyribosomes Mutagenesis Site-Directed Parasitology Immunologic diseases. Allergy Ribosomes Apicomplexa |
| Zdroj: | PLoS Pathogens PLoS Pathogens, Vol 12, Iss 12, p e1006085 (2016) |
| ISSN: | 1553-7374 1553-7366 |
| Popis: | Entamoeba histolytica is an enteric pathogen responsible for amoebic dysentery and liver abscess. It alternates between the host-restricted trophozoite form and the infective environmentally-stable cyst stage. Throughout its lifecycle E. histolytica experiences stress, in part, from host immune pressure. Conversion to cysts is presumed to be a stress-response. In other systems, stress induces phosphorylation of a serine residue on eukaryotic translation initiation factor-2α (eIF2α). This inhibits eIF2α activity resulting in a general decline in protein synthesis. Genomic data reveal that E. histolytica possesses eIF2α (EheIF2α) with a conserved phosphorylatable serine at position 59 (Ser59). Thus, this pathogen may have the machinery for stress-induced translational control. To test this, we exposed cells to different stress conditions and measured the level of total and phospho-EheIF2α. Long-term serum starvation, long-term heat shock, and oxidative stress induced an increase in the level of phospho-EheIF2α, while short-term serum starvation, short-term heat shock, or glucose deprivation did not. Long-term serum starvation also caused a decrease in polyribosome abundance, which is in accordance with the observation that this condition induces phosphorylation of EheIF2α. We generated transgenic cells that overexpress wildtype EheIF2α, a non-phosphorylatable variant of eIF2α in which Ser59 was mutated to alanine (EheIF2α-S59A), or a phosphomimetic variant of eIF2α in which Ser59 was mutated to aspartic acid (EheIF2α-S59D). Consistent with the known functions of eIF2α, cells expressing wildtype or EheIF2α-S59D exhibited increased or decreased translation, respectively. Surprisingly, cells expressing EheIF2α-S59A also exhibited reduced translation. Cells expressing EheIF2α-S59D were more resistant to long-term serum starvation underscoring the significance of EheIF2α phosphorylation in managing stress. Finally, phospho-eIF2α accumulated during encystation in E. invadens, a model encystation system. Together, these data demonstrate that the eIF2α-dependent stress response system is operational in Entamoeba species. Author Summary Entamoeba histolytica is the causative agent of amoebic dysentery and liver abscess and is prevalent in underdeveloped countries that lack proper sanitation. Infection is acquired by ingestion of the cyst form in contaminated food or water. During infection, the parasite experiences stress including demanding growth conditions and host immune pressure. Conversion to the infective cyst may be induced by such stress. In other organisms, stress causes a decrease in protein biosynthesis by inducing phosphorylation of eIF2α, which participates in translation initiation. We exposed E. histolytica to six different stress conditions and observed that some of these conditions (long-term serum starvation, long-term heat shock, and oxidative stress) induced an increase in the level of phospho-eIF2α. Long-term serum starvation was also accompanied by a decrease in mRNA translation. A cell line expressing a mutant version of eIF2α that behaves as a phosphomimetic exhibited decreased translation and increased survival during long-term serum starvation. Finally, phospho-eIF2α accumulated in cysts of E. invadens, a reptilian pathogen that readily encysts in vitro. Together, these data demonstrate that the eIF2α-dependent stress response system is operational in Entamoeba and may regulate encystation. |
| Databáze: | OpenAIRE |
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