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G3 (Bethesda, Md.) Nov 2023Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder...
Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder caused by underlying telomere/telomerase-related mutations. Cells from these patients offer an opportunity to study telomere-related aging and senescence. Our previous work has found that telomere shortening stimulates DNA damage responses (DDRs) and increases reactive oxygen species (ROS), thereby promoting entry into senescence. This work also found that telomere elongation via TERT expression, the catalytic component of the telomere-elongating enzyme telomerase, or p53 shRNA could decrease ROS by disrupting this telomere-DDR-ROS pathway. To further characterize this pathway, we performed a CRISPR/Cas9 knockout screen to identify genes that extend life span in DC cells. Of the cellular clones isolated due to increased life span, 34% had a guide RNA (gRNA) targeting CEBPB, while gRNAs targeting WSB1, MED28, and p73 were observed multiple times. CEBPB is a transcription factor associated with activation of proinflammatory response genes suggesting that inflammation may be present in DC cells. The inflammatory response was investigated using RNA sequencing to compare DC and control cells. Expression of inflammatory genes was found to be significantly elevated (P < 0.0001) in addition to a key subset of these inflammation-related genes [IL1B, IL6, IL8, IL12A, CXCL1 (GROa), CXCL2 (GROb), and CXCL5]. which are regulated by CEBPB. Exogenous TERT expression led to downregulation of RNA/protein CEBPB expression and the inflammatory response genes suggesting a telomere length-dependent mechanism to regulate CEBPB. Furthermore, unlike exogenous TERT and p53 shRNA, CEBPB shRNA did not significantly decrease ROS suggesting that CEBPB's contribution in DC cells' senescence is ROS independent. Our findings demonstrate a key role for CEBPB in engaging senescence by mobilizing an inflammatory response within DC cells.
Topics: Humans; Reactive Oxygen Species; Dyskeratosis Congenita; Telomerase; Tumor Suppressor Protein p53; Mutation; Telomere; RNA, Small Interfering; Fibroblasts; Inflammation; Mediator Complex; CCAAT-Enhancer-Binding Protein-beta
PubMed: 37717172
DOI: 10.1093/g3journal/jkad207 -
The Journal of Biological Chemistry Sep 2023The levels of non-coding RNAs (ncRNAs) are regulated by transcription, RNA processing, and RNA degradation pathways. One mechanism for the degradation of ncRNAs involves... (Review)
Review
The levels of non-coding RNAs (ncRNAs) are regulated by transcription, RNA processing, and RNA degradation pathways. One mechanism for the degradation of ncRNAs involves the addition of oligo(A) tails by non-canonical poly(A) polymerases, which then recruit processive sequence-independent 3' to 5' exonucleases for RNA degradation. This pathway of decay is also regulated by three 3' to 5' exoribonucleases, USB1, PARN, and TOE1, which remove oligo(A) tails and thereby can protect ncRNAs from decay in a manner analogous to the deubiquitination of proteins. Loss-of-function mutations in these genes lead to premature degradation of some ncRNAs and lead to specific human diseases such as Poikiloderma with Neutropenia (PN) for USB1, Dyskeratosis Congenita (DC) for PARN and Pontocerebellar Hypoplasia type 7 (PCH7) for TOE1. Herein, we review the biochemical properties of USB1, PARN, and TOE1, how they modulate ncRNA levels, and their roles in human diseases.
Topics: Humans; Dyskeratosis Congenita; Exoribonucleases; Neutropenia; RNA Stability; RNA, Untranslated; Loss of Function Mutation
PubMed: 37544646
DOI: 10.1016/j.jbc.2023.105139 -
The Journal of Clinical Investigation May 2015Dyskeratosis congenita (DC) is an inherited BM failure disorder that is associated with mutations in genes involved with telomere function and maintenance; however, the...
Dyskeratosis congenita (DC) is an inherited BM failure disorder that is associated with mutations in genes involved with telomere function and maintenance; however, the genetic cause of many instances of DC remains uncharacterized. In this issue of the JCI, Tummala and colleagues identify mutations in the gene encoding the poly(A)-specific ribonuclease (PARN) in individuals with a severe form of DC in three different families. PARN deficiency resulted in decreased expression of genes required for telomere maintenance and an aberrant DNA damage response, including increased levels of p53. Together, the results of this study support PARN as a DC-associated gene and suggest a potential link between p53 and telomere shortening.
Topics: Dyskeratosis Congenita; Exoribonucleases; Female; Humans; Male; Mutation; Telomere Homeostasis
PubMed: 25893598
DOI: 10.1172/JCI81506 -
Annals of Medicine Sep 2014The inherited bone marrow failure syndromes are a diverse group of genetic diseases associated with inadequate production of one or more blood cell lineages. Examples... (Review)
Review
The inherited bone marrow failure syndromes are a diverse group of genetic diseases associated with inadequate production of one or more blood cell lineages. Examples include Fanconi anemia, dyskeratosis congenita, Diamond-Blackfan anemia, thrombocytopenia absent radii syndrome, severe congenital neutropenia, and Shwachman-Diamond syndrome. The management of these disorders was once the exclusive domain of pediatric subspecialists, but increasingly physicians who care for adults are being called upon to diagnose or treat these conditions. Through a series of patient vignettes, we highlight the clinical manifestations of inherited bone marrow failure syndromes in adolescents and young adults. The diagnostic and therapeutic challenges posed by these diseases are discussed.
Topics: Adolescent; Adult; Anemia, Aplastic; Anemia, Diamond-Blackfan; Bone Marrow Diseases; Bone Marrow Failure Disorders; Congenital Bone Marrow Failure Syndromes; Dyskeratosis Congenita; Exocrine Pancreatic Insufficiency; Fanconi Anemia; Hemoglobinuria, Paroxysmal; Humans; Lipomatosis; Neutropenia; Radius; Shwachman-Diamond Syndrome; Thrombocytopenia; Upper Extremity Deformities, Congenital; Young Adult
PubMed: 24888387
DOI: 10.3109/07853890.2014.915579 -
The Annals of Otology, Rhinology, and... Sep 2022Dyskeratosis congenita (DC) is a progressive congenital disorder that predisposes patients to squamous cell cancers (SCC) of the head and neck. We report a case of a...
OBJECTIVES
Dyskeratosis congenita (DC) is a progressive congenital disorder that predisposes patients to squamous cell cancers (SCC) of the head and neck. We report a case of a patient who underwent primary osteocutaneous free flap for mandibular SCC followed by additional treatments for positive margins and discuss a systematic review on therapeutic management for this patient population.
METHODS
Case report of a 39-year-old male with DC who underwent resection and reconstruction with a fibular free flap for mandible SCC, followed by revision surgery and adjuvant radiotherapy for positive margins. A systematic review was completed afterward with the following terms: "dyskeratosis congenita" AND "oral cancer" OR "head and neck" OR "otolaryngology" on Medline and Web of Science for articles between 1980 and 2021. In total, 12 articles were included that reported on DC and SCC in the head and neck.
RESULTS
Of the case reports that were included in this review, half the patients had recurrence within 1 year of primary treatments. Only 2 patients did not require revision surgery, adjuvant, or salvage therapy. Half of patients that received radiation therapy had severe side effects.
CONCLUSIONS
This is the largest review of DC and SCC in the head and neck. Based off our case report and review, these patients have aggressive disease that often requires multi-modality treatment. Consideration should be taken in regards to reports of side effects with radiation therapy.
Topics: Adult; Carcinoma, Squamous Cell; Epithelial Cells; Free Tissue Flaps; Head and Neck Neoplasms; Humans; Male; Plastic Surgery Procedures
PubMed: 34651516
DOI: 10.1177/00034894211047470 -
Frontiers in Oncology 2023Dyskeratosis congenita (DKC), also known as Zinsser-Cole-Engman syndrome, is a telomeropathy typically presenting as a triad of leukoplakia, nail dystrophy, and...
Dyskeratosis congenita (DKC), also known as Zinsser-Cole-Engman syndrome, is a telomeropathy typically presenting as a triad of leukoplakia, nail dystrophy, and reticular hyperpigmentation. Reported genetic mutations linked to DKC include , , , , , , , , and . Homozygous, compound heterozygous, and heterozygous mutations in (, regulator of telomere elongation helicase 1) gene on chromosome 20q13 are known to cause autosomal dominant as well as recessive DKC. Pathogenic variants of gene in patients include c.2288G>T (p. Gly763Val), c.3791G>A (p. Arg1264His), and p. Arg981Trp. We report a novel homozygous variant of , transcript ID: ENST00000360203.11, exon 24, c.2060C>T (p.Ala687Val), in a patient of DKC presenting with leukoplakia, dystrophic nails, reticulate pigmentation, and positive family history of a similar phenotype. The novel variant, reported as a variant of uncertain significance, may therefore be considered diagnostic for DKC in a Pakistani population.
PubMed: 36937416
DOI: 10.3389/fonc.2023.1098876 -
Reconsidering the indication of haematopoietic stem cell transplantation for dyskeratosis congenita.British Journal of Haematology Oct 2018
Topics: Decision Making; Dyskeratosis Congenita; Hematopoietic Stem Cell Transplantation; Humans
PubMed: 29978455
DOI: 10.1111/bjh.15493 -
Haematologica Jan 2019Inherited bone marrow failure syndromes are experiments of nature characterized by impaired hematopoiesis with cancer and leukemia predisposition. The mutations... (Review)
Review
Inherited bone marrow failure syndromes are experiments of nature characterized by impaired hematopoiesis with cancer and leukemia predisposition. The mutations associated with inherited bone marrow failure syndromes affect fundamental cellular pathways, such as DNA repair, telomere maintenance, or proteostasis. How these disturbed pathways fail to produce sufficient blood cells and lead to leukemogenesis are not understood. The rarity of inherited cytopenias, the paucity of affected primary human hematopoietic cells, and the sometime inadequacy of murine or induced pluripotential stem cell models mean it is difficult to acquire a greater understanding of them. Zebrafish offer a model organism to study gene functions. As vertebrates, zebrafish share with humans many orthologous genes involved in blood disorders. As a model organism, zebrafish provide advantages that include rapid development of transparent embryos, high fecundity (providing large numbers of mutant and normal siblings), and a large collection of mutant and transgenic lines useful for investigating the blood system and other tissues during development. Importantly, recent advances in genomic editing in zebrafish can speedily validate the new genes or novel variants discovered in clinical investigation as causes for marrow failure. Here we review zebrafish as a model organism that phenocopies Fanconi anemia, Diamond-Blackfan anemia, dyskeratosis congenita, Shwachman-Diamond syndrome, congenital amegakaryocytic thrombocytopenia, and severe congenital neutropenia. Two important insights, provided by modeling inherited cytopenias in zebrafish, widen understanding of ribosome biogenesis and TP53 in mediating marrow failure and non-hematologic defects. They suggest that TP53-independent pathways contribute to marrow failure. In addition, zebrafish provide an attractive model organism for drug development.
Topics: Animals; Bone Marrow Failure Disorders; Disease Models, Animal; Genetic Diseases, Inborn; Humans; Tumor Suppressor Protein p53; Zebrafish; Zebrafish Proteins
PubMed: 30573510
DOI: 10.3324/haematol.2018.196105 -
ELife May 2022Dyskeratosis congenita (DC) is a rare genetic disorder characterized by deficiencies in telomere maintenance leading to very short telomeres and the premature onset of...
Dyskeratosis congenita (DC) is a rare genetic disorder characterized by deficiencies in telomere maintenance leading to very short telomeres and the premature onset of certain age-related diseases, including pulmonary fibrosis (PF). PF is thought to derive from epithelial failure, particularly that of type II alveolar epithelial (AT2) cells, which are highly dependent on Wnt signaling during development and adult regeneration. We use human induced pluripotent stem cell-derived AT2 (iAT2) cells to model how short telomeres affect AT2 cells. Cultured DC mutant iAT2 cells accumulate shortened, uncapped telomeres and manifest defects in the growth of alveolospheres, hallmarks of senescence, and apparent defects in Wnt signaling. The GSK3 inhibitor, CHIR99021, which mimics the output of canonical Wnt signaling, enhances telomerase activity and rescues the defects. These findings support further investigation of Wnt agonists as potential therapies for DC-related pathologies.
Topics: Alveolar Epithelial Cells; Dyskeratosis Congenita; Glycogen Synthase Kinase 3; Humans; Induced Pluripotent Stem Cells; Mutation; Telomerase; Telomere
PubMed: 35559731
DOI: 10.7554/eLife.64430 -
Frontiers in Pediatrics 2015Peripheral blood cytopenia in children can be due to a variety of acquired or inherited diseases. Genetic disorders affecting a single hematopoietic lineage are... (Review)
Review
Peripheral blood cytopenia in children can be due to a variety of acquired or inherited diseases. Genetic disorders affecting a single hematopoietic lineage are frequently characterized by typical bone marrow findings, such as lack of progenitors or maturation arrest in congenital neutropenia or a lack of megakaryocytes in congenital amegakaryocytic thrombocytopenia, whereas antibody-mediated diseases such as autoimmune neutropenia are associated with a rather unremarkable bone marrow morphology. By contrast, pancytopenia is frequently associated with a hypocellular bone marrow, and the differential diagnosis includes acquired aplastic anemia, myelodysplastic syndrome, inherited bone marrow failure syndromes such as Fanconi anemia and dyskeratosis congenita, and a variety of immunological disorders including hemophagocytic lymphohistiocytosis. Thorough bone marrow analysis is of special importance for the diagnostic work-up of most patients. Cellularity, cellular composition, and dysplastic signs are the cornerstones of the differential diagnosis. Pancytopenia in the presence of a normo- or hypercellular marrow with dysplastic changes may indicate myelodysplastic syndrome. More challenging for the hematologist is the evaluation of the hypocellular bone marrow. Although aplastic anemia and hypocellular refractory cytopenia of childhood (RCC) can reliably be differentiated on a morphological level, the overlapping pathophysiology remains a significant challenge for the choice of the therapeutic strategy. Furthermore, inherited bone marrow failure syndromes are usually associated with the morphological picture of RCC, and the recognition of these entities is essential as they often present a multisystem disease requiring different diagnostic and therapeutic approaches. This paper gives an overview over the different disease entities presenting with (pan)cytopenia, their pathophysiology, characteristic bone marrow findings, and therapeutic approaches.
PubMed: 26217651
DOI: 10.3389/fped.2015.00064