Roles of the Pumilio domain protein PUF3 in Trypanosoma brucei growth and differentiation

Parasitology ◽  
2020 ◽  
Vol 147 (11) ◽  
pp. 1171-1183
Author(s):  
K. Kamanyi Marucha ◽  
C. Clayton
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Rna Binding ◽  
Ectopic Expression ◽  
Fine Tuning ◽  
Growth Defect ◽  
Binding Studies ◽  
Procyclic Form ◽  
Delayed Differentiation ◽  
Domain Protein

AbstractTrypanosomes strongly rely on post-transcriptional mechanisms to control gene expression. Several Opisthokont Pumilio domain proteins are known to suppress expression when bound to mRNAs. The Trypanosoma brucei Pumilio domain protein PUF3 is a cytosolic mRNA-binding protein that suppresses expression when tethered to a reporter mRNA. RNA-binding studies showed that PUF3 preferentially binds to mRNAs with a classical Pumilio-domain recognition motif, UGUA[U/C]AUU. RNA-interference-mediated reduction of PUF3 in bloodstream forms caused a minor growth defect, but the transcriptome was not affected. Depletion of PUF3 also slightly delayed differentiation to the procyclic form. However, both PUF3 genes could be deleted in cultured bloodstream- and procyclic-form trypanosomes. Procyclic forms without PUF3 also grew somewhat slower than wild-type, but ectopic expression of C-terminally tagged PUF3 impaired their viability. PUF3 was not required for RBP10-induced differentiation of procyclic forms to bloodstream forms. Mass spectrometry revealed no PUF3 binding partners that might explain its suppressive activity. We conclude that PUF3 may have a role in fine-tuning gene expression. Since PUF3 is conserved in all Kinetoplastids, including those that do not infect vertebrates, we suggest that it might confer advantages within the invertebrate host.

scholarly journals Expression of normal levels of the Pumilio domain protein PUF3 is required for optimal growth of Trypanosoma brucei

2019 ◽  
Author(s):  
Kevin Kamanyi Marucha ◽  
Christine Clayton
Keyword(s):  
Trypanosoma Brucei ◽  
Rna Binding ◽  
Specific Binding ◽  
Binding Protein ◽  
Ectopic Expression ◽  
Bloodstream Form ◽  
Fine Tuning ◽  
Growth Defect ◽  
Procyclic Form ◽  
Domain Protein

AbstractThe Trypanosoma brucei pumilio domain protein PUF3 is a cytosolic mRNA-binding protein that suppresses expression when tethered to a reporter mRNA. An induced reduction of PUF3 in bloodstream forms caused a slight growth defect and slightly delayed differentiation to the procyclic form, but the cells lost both defects upon prolonged cultivation. Both PUF3 genes could also be deleted in bloodstream-form and procyclic-form trypanosomes, suggesting that in vitro, at least, these life-cycle stages do not require PUF3. Procyclic forms without PUF3 grew somewhat slower than wild-type, but were able to transform to bloodstream forms after induced expression of the bloodstream-form RNA-binding protein RBP10. In contrast, ectopic expression of C-terminally tagged PUF3 in procyclic forms impaired viability. There was little evidence for specific binding of PUF3 to bloodstream-form mRNAs and RNAi had no significant effect on the transcriptome. Moreover, mass spectrometry revealed no PUF3 binding partners that might explain its suppressive activity. Since PUF3 is conserved in all Kinetoplastids, we suggest that it might be required within the invertebrate host, or perhaps implicated in fine-tuning gene expression.

scholarly journals A potential role for a novel ZC3H5 complex in regulating mRNA translation in Trypanosoma brucei

2020 ◽  
Vol 295 (42) ◽  
pp. 14291-14304
Author(s):  
Kathrin Bajak ◽  
Kevin Leiss ◽  
Christine Clayton ◽  
Esteban Erben
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Affinity Purification ◽  
Critical Role ◽  
Rna Binding Protein ◽  
Mrna Translation

In Trypanosoma brucei and related kinetoplastids, gene expression regulation occurs mostly posttranscriptionally. Consequently, RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Yet, the roles of many RNA-binding proteins are not understood. Our previous research identified the RNA-binding protein ZC3H5 as possibly involved in gene repression, but its role in controlling gene expression was unknown. We here show that ZC3H5 is an essential cytoplasmic RNA-binding protein. RNAi targeting ZC3H5 causes accumulation of precytokinetic cells followed by rapid cell death. Affinity purification and pairwise yeast two-hybrid analysis suggest that ZC3H5 forms a complex with three other proteins, encoded by genes Tb927.11.4900, Tb927.8.1500, and Tb927.7.3040. RNA immunoprecipitation revealed that ZC3H5 is preferentially associated with poorly translated, low-stability mRNAs, the 5′-untranslated regions and coding regions of which are enriched in the motif (U/A)UAG(U/A). As previously found in high-throughput analyses, artificial tethering of ZC3H5 to a reporter mRNA or other complex components repressed reporter expression. However, depletion of ZC3H5 in vivo caused only very minor decreases in a few targets, marked increases in the abundances of very stable mRNAs, an increase in monosomes at the expense of large polysomes, and appearance of “halfmer” disomes containing two 80S subunits and one 40S subunit. We speculate that the ZC3H5 complex might be implicated in quality control during the translation of suboptimal open reading frames.

scholarly journals An Alba-domain protein required for proteome remodelling during trypanosome differentiation and host transition

2021 ◽  
Vol 17 (1) ◽  
pp. e1009239
Author(s):  
Shubha Bevkal ◽  
Arunasalam Naguleswaran ◽  
Ruth Rehmann ◽  
Marcel Kaiser ◽  
Manfred Heller ◽  
...  
Keyword(s):  
Steady State ◽  
Trypanosoma Brucei ◽  
Mitochondrial Respiratory Chain ◽  
Translational Repression ◽  
Tsetse Flies ◽  
Protozoan Parasites ◽  
New Host ◽  
Procyclic Form ◽  
Steady State Levels ◽  
Domain Protein

The transition between hosts is a challenge for digenetic parasites as it is unpredictable. For Trypanosoma brucei subspecies, which are disseminated by tsetse flies, adaptation to the new host requires differentiation of stumpy forms picked up from mammals to procyclic forms in the fly midgut. Here we show that the Alba-domain protein Alba3 is not essential for mammalian slender forms, nor is it required for differentiation of slender to stumpy forms in culture or in mice. It is crucial, however, for the development of T. brucei procyclic forms during the host transition. While steady state levels of mRNAs in differentiating cells are barely affected by the loss of Alba3, there are major repercussions for the proteome. Mechanistically, Alba3 aids differentiation by rapidly releasing stumpy forms from translational repression and stimulating polysome formation. In its absence, parasites fail to remodel their proteome appropriately, lack components of the mitochondrial respiratory chain and show reduced infection of tsetse. Interestingly, Alba3 and the closely related Alba4 are functionally redundant in slender forms, but Alba4 cannot compensate for the lack of Alba3 during differentiation from the stumpy to the procyclic form. We postulate that Alba-domain proteins play similar roles in regulating translation in other protozoan parasites, in particular during life-cycle and host transitions.

scholarly journals Characterization of RBP9 and RBP10, two developmentally regulated RNA-binding proteins in Trypanosoma brucei

Open Biology ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 160159 ◽  
Author(s):  
Luis Miguel De Pablos ◽  
Steve Kelly ◽  
Janaina de Freitas Nascimento ◽  
Jack Sunter ◽  
Mark Carrington
Keyword(s):  
Trypanosoma Brucei ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Ectopic Expression ◽  
Developmentally Regulated ◽  
Mrna Metabolism ◽  
Ribonucleoprotein Complexes ◽  
Processing Body ◽  
External Signals

The fate of an mRNA is determined by its interaction with proteins and small RNAs within dynamic complexes called ribonucleoprotein complexes (mRNPs). In Trypanosoma brucei and related kinetoplastids, responses to internal and external signals are mainly mediated by post-transcriptional processes. Here, we used proximity-dependent biotin identification (BioID) combined with RNA-seq to investigate the changes resulting from ectopic expression of RBP10 and RBP9, two developmentally regulated RNA-binding proteins (RBPs). Both RBPs have reduced expression in insect procyclic forms (PCFs) compared with bloodstream forms (BSFs). Upon overexpression in PCFs, both proteins were recruited to cytoplasmic foci, co-localizing with the processing body marker SCD6. Further, both RBPs altered the transcriptome from a PCF- to a BSF-like pattern. Notably, upon expression of BirA*-RBP9 and BirA*-RBP10, BioID yielded more than 200 high confidence protein interactors (more than 10-fold enriched); 45 (RBP9) and 31 (RBP10) were directly related to mRNA metabolism. This study validates the use of BioID for investigating mRNP components but also illustrates the complexity of mRNP function.

scholarly journals EBV noncoding RNA EBER2 interacts with host RNA-binding proteins to regulate viral gene expression

2016 ◽  
Vol 113 (12) ◽  
pp. 3221-3226 ◽  
Author(s):  
Nara Lee ◽  
Therese A. Yario ◽  
Jessica S. Gao ◽  
Joan A. Steitz
Keyword(s):  
Gene Expression ◽  
Noncoding Rna ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Lytic Replication ◽  
Nuclear Bodies ◽  
Viral Gene ◽  
Mrna Levels ◽  
Binding Studies

Epstein–Barr virus (EBV) produces a highly abundant noncoding RNA called EBV-encoded RNA 2 (EBER2) that interacts indirectly with the host transcription factor paired box protein 5 (PAX5) to regulate viral latent membrane protein 1/2 (LMP1/2) gene expression as well as EBV lytic replication. To identify intermediary proteins, we isolated EBER2–PAX5-containing complexes and analyzed the protein components by mass spectrometry. The top candidates include three host proteins splicing factor proline and glutamine rich (SFPQ), non-POU domain-containing octamer-binding protein (NONO), and RNA binding motif protein 14 (RBM14), all reported to be components of nuclear bodies called paraspeckles. In vivo RNA–protein crosslinking indicates that SFPQ and RBM14 contact EBER2 directly. Binding studies using recombinant proteins demonstrate that SFPQ and NONO associate with PAX5, potentially bridging its interaction with EBER2. Similar to EBER2 or PAX5 depletion, knockdown of any of the three host RNA-binding proteins results in the up-regulation of viral LMP2A mRNA levels, supporting a physiologically relevant interaction of these newly identified factors with EBER2 and PAX5. Identification of these EBER2-interacting proteins enables the search for cellular noncoding RNAs that regulate host gene expression in a manner similar to EBER2.

MicroRNAs Act as Decoy Molecules To Restore Granulocytic Maturation of Differentiation-Arrested BCR/ABL+ Myeloid Precursors.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 31-31 ◽  
Author(s):  
Anna M. Eiring ◽  
Paolo Neviani ◽  
George A. Calin ◽  
Denis C. Roy ◽  
Carlo M. Croce ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Rna Binding ◽  
Regulation Of Gene Expression ◽  
Ectopic Expression ◽  
Negative Regulator ◽  
Myelogenous Leukemia ◽  
Imatinib Treatment ◽  
E2 Protein ◽  
Post Transcriptional Regulation

Abstract Altered microRNA (miR) expression contributes to aberrant post-transcriptional regulation of gene expression in different type of cancers; however, their role in the pathogenesis and progression of chronic myelogenous leukemia (CML) from chronic phase (CML-CP) to blast crisis (CML-BC) is still largely unknown. Microarray analysis of miR expression reveals that a discrete number of miRs are significantly upregulated (∼ 6.7% of the total 505 miRs present on the chip; 34 miRs) or downregulated (∼2.8% of the miRs present on the chip; 14 miRs) in an imatinib-sensitive manner in CML-BCCD34+ compared to CML-CPCD34+ progenitors and in BCR/ABL-expressing hematopoietic cell lines compared to untransformed parental cells. Among them, we focused our attention on miR-223, miR-15a/16-1 and miR-328, a microRNA with no currently known function, because of their importance in myelopoiesis, potential role as tumor suppressors and sequence homology with the 5’UTR of CEBPA mRNA, respectively. In 32D-BCR/ABL and K562 cells, Northern blot and TaqMan RT-PCR analyses revealed that expression of miR-223, miR-328, miR-15a and miR-16-1 was markedly suppressed (50–75% inhibition) by p210-BCR/ABL kinase activity and that imatinib treatment (1mM; 24h) restored the expression of these miRs to levels similar to those detected in non-transformed 32Dcl3 cells. Interestingly, sequence analysis of both miR-223 and miR-328 revealed homology with the hnRNP E2-binding site contained in the CEBPA uORF/spacer mRNA, a known target of the negative regulator of myeloid differentiation hnRNP E2. Accordingly, REMSA and UV-crosslinking experiments showed that synthetic miR-223 and to a greater extent miR-328 bind efficiently to recombinant hnRNP E2 protein and compete for its binding to an oligoribonucleotide containing the CEBPA uORF/spacer region, which is required for hnRNP E2-mediated translational inhibition of CEBPA in CML-BCCD34+ progenitors. Furthermore, both miR-223 and miR-328 bind endogenous hnRNP E2 from lysates of BCR/ABL-expressing but not parental cells, and from lysates of parental 32Dcl3 myeloid precursors ectopically expressing a Flag-tagged hnRNP E2 protein, suggesting that miR-223 and miR-328 may act as decoy molecules that interfere with the translation-inhibitory activity of hnRNP E2. Indeed, ectopic expression of miR-223 restored G-CSF-driven granulocytic maturation of differentiation-arrested 32D-BCR/ABL cells and restored C/EBPα expression, whereas it did not have any effect on cytokine-independent growth and clonogenic potential. Consistent with its ability to bind hnRNP E2, miR-328 also rescued C/EBPα expression and differentiation of cytokine-independent BCR/ABL-expressing myeloid precursor 32Dcl3 cells. By contrast, BCR/ABL-dependent colony formation was markedly reduced by overexpression of miR-15a and miR-16-1 (65–75% inhibition, P<0.001) and slightly decreased (40–50% inhibition, P<0.01) by ectopic miR-328 expression. Altogether, these data not only reinforce the importance of BCR/ABL-dependent post-transcriptional regulation of gene expression during CML disease progression but also suggest a new function for microRNAs as functional regulators of RNA binding proteins involved in the control of malignant cell growth, survival and differentiation.

scholarly journals Dicing the Disease with Dicer: The Implications of Dicer Ribonuclease in Human Pathologies

2020 ◽  
Vol 21 (19) ◽  
pp. 7223 ◽  
Author(s):  
Eleni I. Theotoki ◽  
Vasiliki I. Pantazopoulou ◽  
Stella Georgiou ◽  
Panos Kakoulidis ◽  
Vicky Filippa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cardiovascular Diseases ◽  
Protein Expression ◽  
Rna Binding ◽  
Fine Tuning ◽  
Aberrant Expression ◽  
Cellular Processes ◽  
Germ Cell Differentiation ◽  
Pathological Conditions ◽  
Dicer Protein

Gene expression dictates fundamental cellular processes and its de-regulation leads to pathological conditions. A key contributor to the fine-tuning of gene expression is Dicer, an RNA-binding protein (RBPs) that forms complexes and affects transcription by acting at the post-transcriptional level via the targeting of mRNAs by Dicer-produced small non-coding RNAs. This review aims to present the contribution of Dicer protein in a wide spectrum of human pathological conditions, including cancer, neurological, autoimmune, reproductive and cardiovascular diseases, as well as viral infections. Germline mutations of Dicer have been linked to Dicer1 syndrome, a rare genetic disorder that predisposes to the development of both benign and malignant tumors, but the exact correlation of Dicer protein expression within the different cancer types is unclear, and there are contradictions in the data. Downregulation of Dicer is related to Geographic atrophy (GA), a severe eye-disease that is a leading cause of blindness in industrialized countries, as well as to psychiatric and neurological diseases such as depression and Parkinson’s disease, respectively. Both loss and upregulation of Dicer protein expression is implicated in severe autoimmune disorders, including psoriasis, ankylosing spondylitis, rheumatoid arthritis, multiple sclerosis and autoimmune thyroid diseases. Loss of Dicer contributes to cardiovascular diseases and causes defective germ cell differentiation and reproductive system abnormalities in both sexes. Dicer can also act as a strong antiviral with a crucial role in RNA-based antiviral immunity. In conclusion, Dicer is an essential enzyme for the maintenance of physiology due to its pivotal role in several cellular processes, and its loss or aberrant expression contributes to the development of severe human diseases. Further exploitation is required for the development of novel, more effective Dicer-based diagnostic and therapeutic strategies, with the goal of new clinical benefits and better quality of life for patients.

scholarly journals Trypanosoma brucei RRM1 Is a Nuclear RNA-Binding Protein and Modulator of Chromatin Structure

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Arunasalam Naguleswaran ◽  
Kapila Gunasekera ◽  
Bernd Schimanski ◽  
Manfred Heller ◽  
Andrew Hemphill ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Interference ◽  
Heat Shock ◽  
Trypanosoma Brucei ◽  
Chromatin Structure ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Content Type ◽  
Nuclear Rna

ABSTRACT TbRRM1 of Trypanosoma brucei is a nucleoprotein that was previously identified in a search for splicing factors in T. brucei. We show that TbRRM1 associates with mRNAs and with the auxiliary splicing factor polypyrimidine tract-binding protein 2, but not with components of the core spliceosome. TbRRM1 also interacts with several retrotransposon hot spot (RHS) proteins and histones. RNA immunoprecipitation of a tagged form of TbRRM1 from procyclic (insect) form trypanosomes identified ca. 1,500 transcripts that were enriched and 3,000 transcripts that were underrepresented compared to cellular mRNA. Enriched transcripts encoded RNA-binding proteins, including TbRRM1 itself, several RHS transcripts, mRNAs with long coding regions, and a high proportion of stage-regulated mRNAs that are more highly expressed in bloodstream forms. Transcripts encoding ribosomal proteins, other factors involved in translation, and procyclic-specific transcripts were underrepresented. Knockdown of TbRRM1 by RNA interference caused widespread changes in mRNA abundance, but these changes did not correlate with the binding of the protein to transcripts, and most splice sites were unchanged, negating a general role for TbRRM1 in splice site selection. When changes in mRNA abundance were mapped across the genome, regions with many downregulated mRNAs were identified. Two regions were analyzed by chromatin immunoprecipitation, both of which exhibited increases in nucleosome occupancy upon TbRRM1 depletion. In addition, subjecting cells to heat shock resulted in translocation of TbRRM1 to the cytoplasm and compaction of chromatin, consistent with a second role for TbRRM1 in modulating chromatin structure. IMPORTANCE Trypanosoma brucei, the parasite that causes human sleeping sickness, is transmitted by tsetse flies. The parasite progresses through different life cycle stages in its two hosts, altering its pattern of gene expression in the process. In trypanosomes, protein-coding genes are organized as polycistronic units that are processed into monocistronic mRNAs. Since genes in the same unit can be regulated independently of each other, it is believed that gene regulation is essentially posttranscriptional. In this study, we investigated the role of a nuclear RNA-binding protein, TbRRM1, in the insect stage of the parasite. We found that TbRRM1 binds nuclear mRNAs and also affects chromatin status. Reduction of nuclear TbRRM1 by RNA interference or heat shock resulted in chromatin compaction. We propose that TbRRM1 regulates RNA polymerase II-driven gene expression both cotranscriptionally, by facilitating transcription and efficient splicing, and posttranscriptionally, via its interaction with nuclear mRNAs.

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