scholarly journals Stress response in Entamoeba histolytica is associated with robust processing of tRNA to tRNA-halves

2021 ◽  
Author(s):  
Manu Sharma ◽  
Hanbang Zhang ◽  
Gretchen Ehrenkaufer ◽  
Upinder Singh
Keyword(s):  
Gene Expression ◽  
Stress Response ◽  
Environmental Stress ◽  
Developmental Process ◽  
Protein Translation ◽  
Serum Starvation ◽  
Small Rna Sequencing ◽  
Cell Functions ◽  
Argonaute Proteins ◽  
Trna Halves

AbstracttRNA-derived fragments have been reported in many different organisms and have diverse cellular roles such as regulating gene expression, inhibiting protein translation, silencing transposable elements and modulating cell proliferation. In particular tRNA halves, a class of tRNA fragments produced by the cleavage of tRNAs in the anti-codon loop, have been widely reported to accumulate under stress and regulate translation in cells. Here we report the presence of tRNA-derived fragments in Entamoeba with tRNA halves being the most abundant. We further established that tRNA halves accumulate in the parasites upon different stress stimuli such as oxidative stress, heat shock, and serum starvation. We also observed differential expression of tRNA halves during developmental changes of trophozoite to cyst conversion with various tRNA halves accumulating during early encystation. In contrast to other systems, the stress response does not appear to be mediated by a few specific tRNA halves as multiple tRNAs appear to be processed during the various stresses. Furthermore, we identified some tRNA-derived fragments are associated with Entamoeba Argonaute proteins, EhAgo2-2, and EhAgo2-3, which have a preference for different tRNA-derived fragment species. Finally, we show that tRNA halves are packaged inside extracellular vesicles secreted by amoeba. The ubiquitous presence of tRNA-derived fragments, their association with the Argonaute proteins, and the accumulation of tRNA halves during multiple different stresses including encystation suggest a nuanced level of gene expression regulation mediated by different tRNA-derived fragments in Entamoeba.ImportancetRNA-derived fragments are small RNAs formed by the cleavage of tRNAs at specific positions. These have been reported in many organisms to modulate gene expression and thus regulate various cell functions. In the present study, we report for the first time the presence of tRNA-derived fragments in Entamoeba. tRNA-derived fragments were identified by bioinformatics analyses of small RNA sequencing datasets from the parasites and also confirmed experimentally. We found that tRNA halves accumulated in parasites exposed to environmental stress or during developmental process of encystation. We also found that shorter tRNA-derived fragments are bound to Entamoeba Argonaute proteins, indicating that they may have a potential role in the Argonaute-mediated RNA-interference pathway which mediates robust gene silencing in Entamoeba. Our results suggest that tRNA-derived fragments in Entamoeba have a possible role in regulating gene expression during environmental stress.

scholarly journals The environmental stress response causes ribosome loss in aneuploid yeast cells

2020 ◽  
Vol 117 (29) ◽  
pp. 17031-17040 ◽  
Author(s):  
Allegra Terhorst ◽  
Arzu Sandikci ◽  
Abigail Keller ◽  
Charles A. Whittaker ◽  
Maitreya J. Dunham ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stress Response ◽  
Stationary Phase ◽  
Environmental Stress ◽  
Budding Yeast ◽  
Expression Patterns ◽  
Yeast Cells ◽  
Specific Gene ◽  
Environmental Stress Response ◽  
Cellular Stresses

Aneuploidy, a condition characterized by whole chromosome gains and losses, is often associated with significant cellular stress and decreased fitness. However, how cells respond to the aneuploid state has remained controversial. In aneuploid budding yeast, two opposing gene-expression patterns have been reported: the “environmental stress response” (ESR) and the “common aneuploidy gene-expression” (CAGE) signature, in which many ESR genes are oppositely regulated. Here, we investigate this controversy. We show that the CAGE signature is not an aneuploidy-specific gene-expression signature but the result of normalizing the gene-expression profile of actively proliferating aneuploid cells to that of euploid cells grown into stationary phase. Because growth into stationary phase is among the strongest inducers of the ESR, the ESR in aneuploid cells was masked when stationary phase euploid cells were used for normalization in transcriptomic studies. When exponentially growing euploid cells are used in gene-expression comparisons with aneuploid cells, the CAGE signature is no longer evident in aneuploid cells. Instead, aneuploid cells exhibit the ESR. We further show that the ESR causes selective ribosome loss in aneuploid cells, providing an explanation for the decreased cellular density of aneuploid cells. We conclude that aneuploid budding yeast cells mount the ESR, rather than the CAGE signature, in response to aneuploidy-induced cellular stresses, resulting in selective ribosome loss. We propose that the ESR serves two purposes in aneuploid cells: protecting cells from aneuploidy-induced cellular stresses and preventing excessive cellular enlargement during slowed cell cycles by down-regulating translation capacity.

scholarly journals Angiogenesis Induced By Aminoacyl-tRNA Synthetase Deficiency Is Dependent on Amino Acid Response (AAR) but Not Unfolded Protein Response (UPR) Pathways

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 77-77
Author(s):  
Fan Zhang ◽  
Yi Chen ◽  
Yi Jin ◽  
Chun-Hui Xu ◽  
Dian-Jia Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Stress Response ◽  
Unfolded Protein Response ◽  
Blood Vessels ◽  
Protein Translation ◽  
Trna Synthetase ◽  
Unfolded Protein ◽  
Protein Response ◽  
Amino Acid Response

Abstract Stress-induced angiogenesis enormously contributes to both normal development and pathogenesis of various diseases including cancer. Among many stress response pathways implicated in regulation of angiogenesis, the amino acid response (AAR) and the unfolded protein response (UPR) pathways are closely interconnected, as they converge on the common target, eIF2α, which is a key regulator of protein translation. Two kinases, namely Gcn2 (Eif2ak4) and Perk (Eif2ak3), are responsible for transducing signals from AAR and UPR, respectively, to phosphorylation of eIF2α. Even though numerous studies have been performed, this close interconnection between AAR and UPR makes it difficult to clearly distinguish different contributions of these two pathways in regulation of angiogenesis. In this study, we generated a zebrafish angiogenic model harboring a loss-of-function mutation of the threonyl-tRNA synthetase (tars) gene. Tars belongs to a family of evolutionarily conserved enzymes, aminoacyl-tRNA synthetases (aaRSs), which control the first step of protein translation through coupling specific amino acids with their cognate tRNAs. Deficiencies of several aaRSs in zebrafish have been shown to cause increased branching of blood vessels, and this angiogenic phenotype has roughly been explained by activation of AAR and UPR; however, it is unclear whether both AAR and UPR are required and to what extent they contribute to this process. To address this issue, we first performed RNA-seq analyses of Tars-mutated and control zebrafish embryos, as well as those with knockdown of either Gcn2 or Perk in both genotypes. We found that the AAR target genes are dramatically activated in the Tars-mutants, whereas the genes associated with the three UPR sub-pathways (i.e., Perk-, Ire1- and Atf6-mediated pathways) remain inactive, except for very few genes (e.g., Atf3, Atf4, Asns and Igfbp1) that are shared in both AAR and UPR, thus suggesting activation of AAR, but not UPR, in the Tars-mutants. In support of this notion, knockdown of the AAR-associated kinase Gcn2 in the Tars-mutants largely represses the activated genes, while the Perk knockdown shows very little effect. Nonetheless, in contrast to the apparently dispensable role of Perk in Tars-mutants, knockdown of Perk in control embryos leads to specific gene expression alterations, suggesting that Perk effectively functions in homeostatic states (i.e., controls), but, in the stress condition (i.e., Tars-mutants), its function is largely overwhelmed by activation of the Gcn2-mediated AAR. To validate these observations, we investigated the angiogenic phenotypes of the zebrafish models upon genetic and pharmacological interference with the AAR and UPR pathways. A transgenic zebrafish line, Tg(flk1:EGFP), was crossed with the Tars-mutants to visualize angiogenesis in vivo. We observed increased branching of blood vessels in the Tars-mutants, which is rescued by tars mRNA but not an enzymatically dead version. Importantly, knockdown of Gcn2 in the Tars-mutants rescues this phenotype. In contrast, knockdown of Perk, or knockdown of two other known eIF2α kinases, Hri (Eif2ak1) or Pkr (Eif2ak2), shows no effect. Furthermore, knockdown of either one of two major factors downstream to eIF2α, namely Atf4 and Vegfα, or inhibition of Vegf receptor with the drug SU5416, also rescue the phenotype. Thus, these results confirm that AAR, but not UPR, is required for the Tars-deficiency-induced angiogenesis. Taken together, this study demonstrates that, despite being closely interconnected and even sharing a common downstream target, the Gcn2-mediated AAR and the Perk-mediated UPR can be activated independently in different conditions and differentially regulate cellular functions such as angiogenesis. This notion reflects the specificity and efficiency of multiple stress response pathways that are evolved integrally to benefit the organism by ensuring sensing and responding precisely to different types of stresses. This study also provides an example of combining systematic gene expression profiling and phenotypic validations to distinguish activities of such interconnected pathways. Further clarification of the mechanisms shall advance our understanding of how the organisms respond to diverse stresses and how the abnormalities in these regulatory machineries cause cellular stress-related diseases such as cancer, diabetes and immune disorders. Disclosures No relevant conflicts of interest to declare.

scholarly journals 5′ValCAC tRNA fragment generated as part of a protective angiogenin response provides prognostic value in amyotrophic lateral sclerosis

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Marion C Hogg ◽  
Megan Rayner ◽  
Sergej Susdalzew ◽  
Naser Monsefi ◽  
Martin Crivello ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Stress Response ◽  
Disease Progression ◽  
Prognostic Value ◽  
Amyotrophic Lateral Sclerosis Patient ◽  
Protein Translation ◽  
Small Rna Sequencing ◽  
Loss Of Function ◽  
Specific Subset ◽  
Lateral Sclerosis

Abstract Loss-of-function mutations in the ribonuclease angiogenin are associated with amyotrophic lateral sclerosis. Angiogenin has been shown to cleave transfer RNAs during stress to produce ‘transfer-derived stress-induced RNAs’. Stress-induced tRNA cleavage is preserved from single-celled organisms to humans indicating it represents part of a highly conserved stress response. However, to date, the role of tRNA cleavage in amyotrophic lateral sclerosis remains to be fully elucidated. To this end, we performed small RNA sequencing on a human astrocytoma cell line to identify the complete repertoire of tRNA fragments generated by angiogenin. We found that only a specific subset of tRNAs is cleaved by angiogenin and identified 5′ValCAC transfer-derived stress-induced RNA to be secreted from neural cells. 5′ValCAC was quantified in spinal cord and serum from SOD1G93A amyotrophic lateral sclerosis mouse models where we found it to be significantly elevated at symptom onset correlating with increased angiogenin expression, imbalanced protein translation initiation factors and slower disease progression. In amyotrophic lateral sclerosis patient serum samples, we found 5′ValCAC to be significantly higher in patients with slow disease progression, and interestingly, we find 5′ValCAC to hold prognostic value for amyotrophic lateral sclerosis patients. Here, we report that angiogenin cleaves a specific subset of tRNAs and provide evidence for 5′ValCAC as a prognostic biomarker in amyotrophic lateral sclerosis. We propose that increased serum 5′ValCAC levels indicate an enhanced angiogenin-mediated stress response within motor neurons that correlates with increased survival. These data suggest that the previously reported beneficial effects of angiogenin in SOD1G93A mice may result from elevated levels of 5′ValCAC transfer RNA fragment.

scholarly journals tRNA-derived fragments and microRNAs in the maternal-fetal interface of a mouse maternal-immune-activation autism model

2019 ◽  
Author(s):  
Zhangli Su ◽  
Elizabeth L. Frost ◽  
Catherine R. Lammert ◽  
Roza K. Przanowska ◽  
John R. Lukens ◽  
...  
Keyword(s):  
Environmental Stress ◽  
Immune Activation ◽  
Fetal Liver ◽  
Fetal Brain ◽  
Protein Translation ◽  
Maternal Immune Activation ◽  
Acute Response ◽  
Mouse Placenta ◽  
Trna Halves ◽  
Maternal Fetal Interface

AbstracttRNA-derived small fragments (tRFs) and tRNA halves have emerging functions in different biological pathways, such as regulating gene expression, protein translation, retrotransposon activity, transgenerational epigenetic changes and response to environmental stress. However, small RNAs like tRFs and microRNAs in the maternal-fetal interface during gestation have not been studied extensively. Here we investigated the small RNA composition of mouse placenta/decidua, which represents the interface where the mother communicates with the fetus, to determine whether there are specific differences in tRFs and microRNAs during fetal development and in response to maternal immune activation (MIA). Global tRF expression pattern, just like microRNAs, can distinguish tissue types among placenta/decidua, fetal brain and fetal liver. In particular, 5’ tRNA halves from tRNAGly, tRNAGlu, tRNAVal and tRNALys are abundantly expressed in the normal mouse placenta/decidua. Moreover, tRF and microRNA levels in the maternal-fetal-interface change dynamically over the course of embryonic development. To see if stress alters non-coding RNA expression at the maternal-fetal interface, we treated pregnant mice with a viral infection mimetic, which has been shown to promote autism-related phenotypes in the offspring. Acute changes in the levels of specific tRFs and microRNAs were observed 3-6 hours after MIA and are suppressed thereafter. A group of 5’ tRNA halves is down-regulated by MIA, whereas a group of 18-nucleotide tRF-3a is up-regulated. In conclusion, tRFs show tissue-specificity, developmental changes and acute response to environmental stress, opening the possibility of them having a role in the fetal response to MIA.

scholarly journals The environmental stress response causes ribosome loss in aneuploid yeast cells

2020 ◽  
Author(s):  
Allegra Terhorst ◽  
Arzu Sandikci ◽  
Abigail Keller ◽  
Charles A. Whittaker ◽  
Maitreya J. Dunham ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stress Response ◽  
Stationary Phase ◽  
Environmental Stress ◽  
Budding Yeast ◽  
Expression Patterns ◽  
Yeast Cells ◽  
Specific Gene ◽  
Environmental Stress Response ◽  
Cellular Stresses

AbstractAneuploidy, a condition characterized by whole chromosome gains and losses, is often associated with significant cellular stress and decreased fitness. However, how cells respond to the aneuploid state has remained controversial. In aneuploid budding yeast, two opposing gene expression patterns have been reported: the “environmental stress response” (ESR) and the “common aneuploidy gene-expression” (CAGE) signature, in which many ESR genes are oppositely regulated. Here, we investigate and bring clarity to this controversy. We show that the CAGE signature is not an aneuploidy-specific gene expression signature but the result of normalizing the gene expression profile of actively proliferating aneuploid cells to that of euploid cells grown into stationary phase. Because growth into stationary phase is amongst the strongest inducers of the ESR, the ESR in aneuploid cells was masked when stationary phase euploid cells were used for normalization in transcriptomic studies. When exponentially growing euploid cells are used in gene expression comparisons with aneuploid cells, the CAGE signature is no longer evident in aneuploid cells. Instead, aneuploid cells exhibit the ESR. We further show that the ESR causes selective ribosome loss in aneuploid cells, providing an explanation for the decreased cellular density of aneuploid cells. We conclude that aneuploid budding yeast cells mount the ESR, rather than the CAGE signature, in response to aneuploidy-induced cellular stresses, resulting in selective ribosome loss. We propose that the ESR serves two purposes in aneuploid cells: protecting cells from aneuploidy-induced cellular stresses and preventing excessive cellular enlargement during slowed cell cycles by downregulating translation capacity.

scholarly journals A dataset to explore kinase control of environmental stress responsive transcription

2019 ◽  
Author(s):  
Kieran Mace ◽  
Joanna Krakowiak ◽  
Hana El-Samad ◽  
David Pincus
Keyword(s):  
Gene Expression ◽  
Stress Response ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Target Genes ◽  
Growth Control ◽  
Gene Expression Signature ◽  
Negative Regulator ◽  
Cellular Stress Response ◽  
Environmental Stress Response

ABSTRACTCells respond to changes in environmental conditions by activating signal transduction pathways and gene expression programs. Here we present a dataset to explore the relationship between environmental stresses, kinases, and global gene expression in yeast. We subjected 28 drug-sensitive kinase mutants to 10 environmental conditions in the presence of inhibitor and performed mRNA deep sequencing. With these data, we reconstructed canonical stress pathways and identified examples of crosstalk among pathways. The data also implicated numerous kinases in novel environment-specific roles. However, rather than regulating dedicated sets of target genes, individual kinases tuned the magnitude of induction of the environmental stress response (ESR) – a gene expression signature shared across the set of perturbations – in environment-specific ways. This suggests that the ESR integrates inputs from multiple sensory kinases to modulate gene expression and growth control. As an example, we provide experimental evidence that the high osmolarity glycerol pathway is a constitutive negative regulator of protein kinase A, a known inhibitor of the ESR. These results elaborate the central axis of cellular stress response signaling.

scholarly journals Global Gene Expression Responses of Fission Yeast to Ionizing Radiation

2004 ◽  
Vol 15 (2) ◽  
pp. 851-860 ◽  
Author(s):  
Adam Watson ◽  
Juan Mata ◽  
Jürg Bähler ◽  
Anthony Carr ◽  
Tim Humphrey
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Stress Response ◽  
Ionizing Radiation ◽  
Environmental Stress ◽  
Fission Yeast ◽  
Transcriptional Response ◽  
Global Gene Expression ◽  
Environmental Stress Response ◽  
Stress Response Genes

A coordinated transcriptional response to DNA-damaging agents is required to maintain genome stability. We have examined the global gene expression responses of the fission yeast Schizosaccharomyces pombe to ionizing radiation (IR) by using DNA microarrays. We identified ∼200 genes whose transcript levels were significantly altered at least twofold in response to 500 Gy of gamma IR in a temporally defined manner. The majority of induced genes were core environmental stress response genes, whereas the remaining genes define a transcriptional response to DNA damage in fission yeast. Surprisingly, few DNA repair and checkpoint genes were transcriptionally modulated in response to IR. We define a role for the stress-activated mitogen-activated protein kinase Sty1/Spc1 and the DNA damage checkpoint kinase Rad3 in regulating core environmental stress response genes and IR-specific response genes, both independently and in concert. These findings suggest a complex network of regulatory pathways coordinate gene expression responses to IR in eukaryotes.

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