scholarly journals Saccharomyces cerevisiae strains display robust phenotypes in the presence of Dyskeratosis congenita mutations in the Cbf5 gene

2019 ◽  
Author(s):  
Abeer Abdullah Ogailan ◽  
Anne C. Rintala-Dempsey ◽  
Ute Kothe
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosome Biogenesis ◽  
Bone Marrow Failure ◽  
Growth Curves ◽  
Dyskeratosis Congenita ◽  
Telomerase Rna ◽  
Pseudouridine Synthase ◽  
Relative Contribution ◽  
Rare Congenital Disorder ◽  
Different Temperatures

AbstractDyskeratosis congenita is a rare, congenital disorder affecting the skin, nails and oral mucosa of patients that often progresses to bone marrow failure and an increased predisposition for a variety of carcinomas. Mutations in the human dyskerin gene have been identified as the most prevalent cause of the disease. Dyskerin is a pseudouridine synthase and the catalytic subunit of H/ACA ribonucleoproteins (RNPs) responsible for the modification of uridines to pseudouridine in ribosomal RNA (rRNA), but dyskerin also binds to the telomerase RNA component (TERC). Accordingly, Dyskeratosis congenita mutations have been reported to affect both telomerase function as well as ribosome biogenesis, but the relative contribution of each pathway to the diseases is under debate. As the yeast homolog of dyskerin, Cbf5, does not interact with telomerase RNA, Saccharomyces cerevisiae is an ideal model to identify the selective impact of Dyskeratosis congenita mutations on ribosome biogenesis. Therefore, chromosomal mutations in the yeast homologue of dyskerin, Cbf5, were introduced at positions corresponding to the mutations in human dyskerin that result in Dyskeratosis congenita. To determine if the mutations affect cellular fitness, we screened for growth defects in yeast. Growth curves at different temperatures and yeast spot assays under several stress conditions revealed that the mutations in cbf5 did not impair growth compared to wild type. These findings suggest that in the yeast cell, Dyskeratosis congenita mutations do not significantly affect ribosome biogenesis, and we discuss the implications for understanding the molecular cause of Dyskeratosis congenita.

scholarly journals DYSKERIN, AN ESSENTIAL PSEUDOURIDINE SYNTHASE WITH MULTIFACETED ROLES IN RIBOSOME BIOGENESIS, SPLICING AND TELOMERE MAINTENANCE

RNA ◽  
2021 ◽  
pp. rna.078953.121
Author(s):  
Alexandre Garus ◽  
Chantal Autexier
Keyword(s):  
Ribosome Biogenesis ◽  
Bone Marrow Failure ◽  
Regulation Of Gene Expression ◽  
Dyskeratosis Congenita ◽  
Premature Aging ◽  
Telomere Maintenance ◽  
Cajal Body ◽  
Translation Efficiency ◽  
Rna Molecules ◽  
Pseudouridine Synthase

Dyskerin and its homologues are ancient and conserved enzymes that catalyse the most common posttranscriptional modification found in cells, pseudouridylation. The resulting pseudouridines provide stability to RNA molecules and regulate ribosome biogenesis and splicing events. Dyskerin does not act independently – it is the core component of a protein heterotetramer, which associates with RNAs that contain the H/ACA motif. The variety of H/ACA RNAs that guide the function of this ribonucleoprotein (RNP) complex highlight the diversity of cellular processes in which dyskerin participates. When associated with small nucleolar (sno) RNAs, it regulates ribosomal (r) RNAs and ribosome biogenesis. By interacting with small Cajal Body (sca) RNAs, it targets small nuclear (sn) RNAs to regulate pre-mRNA splicing. As a component of the telomerase holoenzyme, dyskerin binds to the telomerase RNA to modulate telomere maintenance. In a disease context, dyskerin malfunction can result in multiple detrimental phenotypes. Mutations in DKC1, the gene that encodes dyskerin, cause the premature aging syndrome X-linked dyskeratosis congenita (X-DC), a still incurable disorder that typically leads to bone marrow failure. In this review, we present the classical and most recent findings on this essential protein, discussing the evolutionary, structural and functional aspects of dyskerin and the H/ACA RNP. The latest research underscores the role that dyskerin plays in the regulation of gene expression, translation efficiency and telomere maintenance, along with the impacts that defective dyskerin has on aging, cell proliferation, haematopoietic potential and cancer.

Ribosome Dysfunction and Ineffective Hematopoiesis.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. SCI-11-SCI-11
Author(s):  
Benjamin L. Ebert
Keyword(s):  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Bone Marrow Failure ◽  
Ribosomal Genes ◽  
Limb Bud ◽  
Refractory Anemia ◽  
Diamond Blackfan Anemia ◽  
Rare Congenital Disorder ◽  
Human Disorders ◽  
And Function

Abstract Abstract SCI-11 The 5q- syndrome and Diamond Blackfan Anemia are related on a molecular level by ribosome dysfunction. The 5q- syndrome is a distinct subtype of myelodysplastic syndrome (MDS) associated with isolated, interstitial deletions of the long arm of Chromosome 5. Diamond Blackfan Anemia is a rare congenital disorder associated with bone marrow failure, craniofacial abnormalities, and limb bud defects. The hematologic phenotype of both diseases includes a severe refractory anemia, macrocytosis, and a deficiency of erythroid precursors. Recent evidence indicates that this erythroid defect is caused by RPS14 deletion in the 5q- syndrome, and by mutation of RPS19 or other ribosomal genes in at least 50% of patients with Diamond Blackfan Anemia. In both diseases, deletion or mutation of one allele of a ribosomal protein leads to defects in pre-rRNA processing and defective production of mature ribosomes. In murine and zebrafish models, haploinsufficiency for ribosomal genes phenocopies the erythroid failure characteristic of the human disorders. While the mechanistic consequences of ribosomal dysfunction have not been fully elucidated, the p53 pathway appears to play a central role. MDM2, an E3 ubiquitin ligase that promotes the degradation of p53, binds to several ribosomal proteins including RPL11. Deficiency of RPS6, and perhaps other ribosomal proteins, causes an accumulation of free RPL11, that binds to MDM2, preventing MDM2 from interacting with p53, thereby leading to an accumulation of p53. Several other genes that are mutated in hematologic disorders are involved in ribosome biogenesis and function, including SBDS, mutated in Shwachman Diamond syndrome; DKC1, mutated in some cases of dyskaratosis congenita; and NPM1, mutated in acute myeloid leukemia and deleted in some cases of MDS. The manner in which each of these genes disrupt ribosome function and cause distinct clinical phenotypes is currently under investigation. Disclosures Ebert: GlaxoSmithKline: Research Funding.

scholarly journals An investigation into eukaryotic pseudouridine synthases

2014 ◽  
Vol 12 (04) ◽  
pp. 1450015 ◽  
Author(s):  
Ross D. King ◽  
Chuan Lu
Keyword(s):  
Biological Significance ◽  
Growth Curves ◽  
Dyskeratosis Congenita ◽  
Growth Data ◽  
Yeast Saccharomyces Cerevisiae ◽  
Biological Regulation ◽  
Pseudouridine Synthase ◽  
Pseudouridine Synthases ◽  
Growth Properties ◽  
Qualitative Effect

A common post-transcriptional modification of RNA is the conversion of uridine to its isomer pseudouridine. We investigated the biological significance of eukaryotic pseudouridine synthases using the yeast Saccharomyces cerevisiae. We conducted a comprehensive statistical analysis on growth data from automated perturbation (gene deletion) experiments, and used bi-logistic curve analysis to characterise the yeast phenotypes. The deletant strains displayed different alteration in growth properties, including in some cases enhanced growth and/or biphasic growth curves not seen in wild-type strains under matched conditions. These results demonstrate that disrupting pseudouridine synthases can have a significant qualitative effect on growth. We further investigated the significance of post-transcriptional pseudouridine modification through investigation of the scientific literature. We found that (1) In Toxoplasma gondii, a pseudouridine synthase gene is critical in cellular differentiation between the two asexual forms: Tachyzoites and bradyzoites; (2) Mutation of pseudouridine synthase genes has also been implicated in human diseases (mitochondrial myopathy and sideroblastic anemia (MLASA); dyskeratosis congenita). Taken together, these results are consistent with pseudouridine synthases having a Gene Ontology function of "biological regulation".

Mutations of the human telomerase RNA gene (TERC) in aplastic anemia and myelodysplastic syndrome

Blood ◽  
2003 ◽  
Vol 102 (3) ◽  
pp. 916-918 ◽  
Author(s):  
Hiroki Yamaguchi ◽  
Gabriela M. Baerlocher ◽  
Peter M. Lansdorp ◽  
Stephen J. Chanock ◽  
Olga Nunez ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
Blood Cells ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Autosomal Dominant ◽  
Bone Marrow Failure ◽  
Dyskeratosis Congenita ◽  
Telomerase Rna ◽  
Number Of Patients ◽  
Human Telomerase

Abstract Mutations in the human telomerase RNA (TERC) occur in autosomal dominant dyskeratosis congenita (DKC). Because of the possibility that TERC mutations might underlie seemingly acquired forms of bone marrow failure, we examined blood samples from a large number of patients with aplastic anemia (AA), paroxysmal nocturnal hemoglobinuria (PNH), and myelodysplasia (MDS). Only 3 of 210 cases showed heterozygous TERC mutations: both nucleotide 305 (n305) (G>A) and n322 (G>A) were within the conserved region (CR) 4–CR5 domain; n450 (G>A) was localized to the boxH/ACA domain. However, only one patient (with a mutation at n305 [G>A]) had clinical characteristics suggesting DKC; her blood cells contained short telomeres and her sister also suffered from bone marrow failure. Another 21 patients with short telomeres did not show TERC mutations. Our results suggest that cryptic DKC, at least secondary to mutations in the TERC gene, is an improbable diagnosis in patients with otherwise typical AA, PNH, and MDS.

scholarly journals Pediatric leukemia susceptibility disorders: manifestations and management

Hematology ◽  
2017 ◽  
Vol 2017 (1) ◽  
pp. 242-250 ◽  
Author(s):  
Lisa J. McReynolds ◽  
Sharon A. Savage
Keyword(s):  
Early Onset ◽  
Ribosome Biogenesis ◽  
De Novo ◽  
Disease Risk ◽  
Bone Marrow Failure ◽  
Clinical Manifestations ◽  
Cancer Surveillance ◽  
Therapeutic Interventions ◽  
Pediatric Leukemia ◽  
Inherited Susceptibility

Abstract The clinical manifestations of inherited susceptibility to leukemia encompass a wide phenotypic range, including patients with certain congenital anomalies or early-onset myelodysplastic syndrome (MDS) and some with no obvious medical problems until they develop leukemia. Leukemia susceptibility syndromes occur as a result of autosomal dominant, autosomal recessive, or X-linked recessive inheritance, or de novo occurrence, of germline pathogenic variants in DNA repair, ribosome biogenesis, telomere biology, hematopoietic transcription factors, tumor suppressors, and other critical cellular processes. Children and adults with cytopenias, MDS, dysmorphic features, notable infectious histories, immunodeficiency, certain dermatologic findings, lymphedema, unusual sensitivity to radiation or chemotherapy, or acute leukemia with a family history of early-onset cancer, pulmonary fibrosis, or alveolar proteinosis should be thoroughly evaluated for a leukemia susceptibility syndrome. Genetic testing and other diagnostic modalities have improved our ability to identify these patients and to counsel them and their family members for subsequent disease risk, cancer surveillance, and therapeutic interventions. Herein, the leukemia susceptibility syndromes are divided into 3 groups: (1) those associated with an underlying inherited bone marrow failure syndrome, (2) disorders in which MDS precedes leukemia development, and (3) those with a risk primarily of leukemia. Although children are the focus of this review, it is important for clinicians to recognize that inherited susceptibility to cancer can present at any age, even in older adults; genetic counseling is essential and prompt referral to experts in each syndrome is strongly recommended.

scholarly journals The Putative RNA Helicase Dbp6p Functionally Interacts With Rpl3p, Nop8p and the Novel trans-acting Factor Rsa3p During Biogenesis of 60S Ribosomal Subunits in Saccharomyces cerevisiae

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1687-1699
Author(s):  
Jesús de la Cruz ◽  
Thierry Lacombe ◽  
Olivier Deloche ◽  
Patrick Linder ◽  
Dieter Kressler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosome Biogenesis ◽  
Null Allele ◽  
Ribosomal Subunit ◽  
Interaction Network ◽  
The Novel ◽  
Rna Helicases ◽  
Ribosomal Subunits ◽  
Synthetic Lethal ◽  
Synthetically Lethal

Abstract Ribosome biogenesis requires at least 18 putative ATP-dependent RNA helicases in Saccharomyces cerevisiae. To explore the functional environment of one of these putative RNA helicases, Dbp6p, we have performed a synthetic lethal screen with dbp6 alleles. We have previously characterized the nonessential Rsa1p, whose null allele is synthetically lethal with dbp6 alleles. Here, we report on the characterization of the four remaining synthetic lethal mutants, which reveals that Dbp6p also functionally interacts with Rpl3p, Nop8p, and the so-far-uncharacterized Rsa3p (ribosome assembly 3). The nonessential Rsa3p is a predominantly nucleolar protein required for optimal biogenesis of 60S ribosomal subunits. Both Dbp6p and Rsa3p are associated with complexes that most likely correspond to early pre-60S ribosomal particles. Moreover, Rsa3p is co-immunoprecipitated with protA-tagged Dbp6p under low salt conditions. In addition, we have established a synthetic interaction network among factors involved in different aspects of 60S-ribosomal-subunit biogenesis. This extensive genetic analysis reveals that the rsa3 null mutant displays some specificity by being synthetically lethal with dbp6 alleles and by showing some synthetic enhancement with the nop8-101 and the rsa1 null allele.

scholarly journals Monitoring and treatment of MDS in genetically susceptible persons

Hematology ◽  
2019 ◽  
Vol 2019 (1) ◽  
pp. 105-109 ◽  
Author(s):  
Stella M. Davies
Keyword(s):  
Bone Marrow ◽  
Dna Damage ◽  
Bone Marrow Failure ◽  
Treatment Strategies ◽  
Informed Choice ◽  
Dyskeratosis Congenita ◽  
Careful Consideration ◽  
Host Susceptibility ◽  
Bone Marrow Failure Syndromes ◽  
Severe Infections

Abstract Genetic susceptibility to myelodysplastic syndrome (MDS) occurs in children with inherited bone marrow failure syndromes, including Fanconi anemia, Shwachman Diamond syndrome, and dyskeratosis congenita. Available evidence (although not perfect) supports annual surveillance of the blood count and bone marrow in affected persons. Optimal treatment of MDS in these persons is most commonly transplantation. Careful consideration must be given to host susceptibility to DNA damage when selecting a transplant strategy, because significant dose reductions and avoidance of radiation are necessary. Transplantation before evolution to acute myeloid leukemia (AML) is optimal, because outcomes of AML are extremely poor. Children and adults can present with germline mutations in GATA2 and RUNX1, both of which are associated with a 30% to 40% chance of evolution to MDS. GATA2 deficiency may be associated with a clinically important degree of immune suppression, which can cause severe infections that can complicate transplant strategies. GATA2 and RUNX1 deficiency is not associated with host susceptibility to DNA damage, and therefore, conventional treatment strategies for MDS and AML can be used. RUNX1 deficiency has a highly variable phenotype, and MDS can occur in childhood and later in adulthood within the same families, making annual surveillance with marrow examination burdensome; however, such strategies should be discussed with affected persons, allowing an informed choice.

scholarly journals Cytoplasmic Recycling of 60S Preribosomal Factors Depends on the AAA Protein Drg1

2007 ◽  
Vol 27 (19) ◽  
pp. 6581-6592 ◽  
Author(s):  
Brigitte Pertschy ◽  
Cosmin Saveanu ◽  
Gertrude Zisser ◽  
Alice Lebreton ◽  
Martin Tengg ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Export ◽  
Ribosome Biogenesis ◽  
Dominant Negative ◽  
Cytoplasmic Localization ◽  
Atpase Domain ◽  
Aaa Atpase ◽  
Cytoplasmic Accumulation ◽  
Functional Inactivation ◽  
Aaa Protein

ABSTRACT Allelic forms of DRG1/AFG2 confer resistance to the drug diazaborine, an inhibitor of ribosome biogenesis in Saccharomyces cerevisiae. Our results show that the AAA-ATPase Drg1 is essential for 60S maturation and associates with 60S precursor particles in the cytoplasm. Functional inactivation of Drg1 leads to an increased cytoplasmic localization of shuttling pre-60S maturation factors like Rlp24, Arx1, and Tif6. Surprisingly, Nog1, a nuclear pre-60S factor, was also relocalized to the cytoplasm under these conditions, suggesting that it is a previously unsuspected shuttling preribosomal factor that is exported with the precursor particles and very rapidly reimported. Proteins that became cytoplasmic under drg1 mutant conditions were blocked on pre-60S particles at a step that precedes the association of Rei1, a later-acting preribosomal factor. A similar cytoplasmic accumulation of Nog1 and Rlp24 in pre-60S-bound form could be seen after overexpression of a dominant-negative Drg1 variant mutated in the D2 ATPase domain. We conclude that the ATPase activity of Drg1 is required for the release of shuttling proteins from the pre-60S particles shortly after their nuclear export. This early cytoplasmic release reaction defines a novel step in eukaryotic ribosome maturation.

scholarly journals Proteotoxicity from aberrant ribosome biogenesis compromises cell fitness

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Blake W Tye ◽  
Nicoletta Commins ◽  
Lillia V Ryazanova ◽  
Martin Wühr ◽  
Michael Springer ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Ribosome Assembly ◽  
Maximal Growth ◽  
Proliferating Cells ◽  
Cellular Processes ◽  
Direct Contribution ◽  
The Face ◽  
Cellular Phenotypes

To achieve maximal growth, cells must manage a massive economy of ribosomal proteins (r-proteins) and RNAs (rRNAs) to produce thousands of ribosomes every minute. Although ribosomes are essential in all cells, natural disruptions to ribosome biogenesis lead to heterogeneous phenotypes. Here, we model these perturbations in Saccharomyces cerevisiae and show that challenges to ribosome biogenesis result in acute loss of proteostasis. Imbalances in the synthesis of r-proteins and rRNAs lead to the rapid aggregation of newly synthesized orphan r-proteins and compromise essential cellular processes, which cells alleviate by activating proteostasis genes. Exogenously bolstering the proteostasis network increases cellular fitness in the face of challenges to ribosome assembly, demonstrating the direct contribution of orphan r-proteins to cellular phenotypes. We propose that ribosome assembly is a key vulnerability of proteostasis maintenance in proliferating cells that may be compromised by diverse genetic, environmental, and xenobiotic perturbations that generate orphan r-proteins.

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