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Journal Der Deutschen Dermatologischen... Aug 2023
PubMed: 37574687
DOI: 10.1111/ddg.15090_g -
Italian Journal of Dermatology and... Jun 2024Telomeres, the safeguarding caps at the tips of chromosomes, are pivotal in the aging process of cells and have been linked to skin ailments and inflammatory conditions.... (Review)
Review
Telomeres, the safeguarding caps at the tips of chromosomes, are pivotal in the aging process of cells and have been linked to skin ailments and inflammatory conditions. Telomeres undergo a gradual reduction in length and factors such as oxidative stress hasten this diminishing process. Skin diseases including inflammatory conditions can be correlated with the shortening of telomeres and the persistent activation of DNA damage response in skin tissues. Telomere dysfunction could disrupt the balance of the skin, impairs wound healing, and may contribute to abnormal cytokine production. Skin aging and processes related to telomeres may function as one of the triggers for skin diseases. The presence of proinflammatory cytokines and dysfunctional telomeres in conditions such as Dyskeratosis Congenita implies a possible connection between the shortening of telomeres and the onset of chronic inflammatory skin disorders. In autoinflammatory skin diseases, chronic inflammation hinders wound healing thus aggravating the progression of the disease. The NF-ĸB pathway might contribute to the initiation or progression of chronic disorders by influencing mechanisms associated with telomere biology. The intricate connections between telomeres, telomerase, telomere-associated proteins, and skin diseases are still a complex puzzle to be solved. Here, we provide an overview of the impact of telomeres on both health and disease with a specific emphasis on their role in skin, inflammation and autoinflammatory skin disorders.
Topics: Humans; Telomere; Skin Diseases; Inflammation; Telomere Shortening; Telomerase; Dyskeratosis Congenita; Skin Aging
PubMed: 38502535
DOI: 10.23736/S2784-8671.23.07689-2 -
International Journal of Molecular... Jan 2024Dyskeratosis Congenita (DC) is a multisystem disorder intrinsically associated with telomere dysfunction, leading to bone marrow failure (BMF). Although the pathology of...
Dyskeratosis Congenita (DC) is a multisystem disorder intrinsically associated with telomere dysfunction, leading to bone marrow failure (BMF). Although the pathology of DC is largely driven by mutations in telomere-associated genes, the implications of gene fusions, which emerge due to telomere-induced genomic instability, remain unexplored. We meticulously analyzed gene fusions in RNA-Seq data from DC patients to provide deeper insights into DC's progression. The most significant DC-specific gene fusions were subsequently put through in silico assessments to ascertain biophysical and structural attributes, including charge patterning, inherent disorder, and propensity for self-association. Selected candidates were then analyzed using deep learning-powered structural predictions and molecular dynamics simulations to gauge their potential for forming higher-order oligomers. Our exploration revealed that genes participating in fusion events play crucial roles in upholding genomic stability, facilitating hematopoiesis, and suppressing tumors. Notably, our analysis spotlighted a particularly disordered polyampholyte fusion protein that exhibits robust higher-order oligomerization dynamics. To conclude, this research underscores the potential significance of several high-confidence gene fusions in the progression of BMF in DC, particularly through the dysregulation of genomic stability, hematopoiesis, and tumor suppression. Additionally, we propose that these fusion proteins might hold a detrimental role, specifically in inducing proteotoxicity-driven hematopoietic disruptions.
Topics: Humans; Dyskeratosis Congenita; Telomerase; Pancytopenia; Bone Marrow Failure Disorders; Mutation; Telomere; Genomic Instability
PubMed: 38338888
DOI: 10.3390/ijms25031606 -
Human Molecular Genetics Feb 2024Dyskerin is a component of the human telomerase complex and is involved in stabilizing the human telomerase RNA (hTR). Many mutations in the DKC1 gene encoding dyskerin...
Dyskerin is a component of the human telomerase complex and is involved in stabilizing the human telomerase RNA (hTR). Many mutations in the DKC1 gene encoding dyskerin are found in X-linked dyskeratosis congenita (X-DC), a premature aging disorder and other related diseases. The C-terminal extension (CTE) of dyskerin contributes to its interaction with the molecular chaperone SHQ1 during the early stage of telomerase biogenesis. Disease mutations in this region were proposed to disrupt dyskerin-SHQ1 interaction and destabilize dyskerin, reducing hTR levels indirectly. However, biochemical evidence supporting this hypothesis is still lacking. In addition, the effects of many CTE disease mutations on hTR have not been examined. In this study, we tested eight dyskerin CTE variants and showed that they failed to maintain hTR levels. These mutants showed slightly reduced but not abolished interaction with SHQ1, and caused defective binding to hTR. Deletion of the CTE further reduced binding to hTR, and perturbed localization of dyskerin to the Cajal bodies and the nucleolus, and the interaction with TCAB1 as well as GAR1. Our findings suggest impaired dyskerin-hTR interaction in cells as a previously overlooked mechanism through which dyskerin CTE mutations cause X-DC and related telomere syndromes.
Topics: Humans; Telomerase; Dyskeratosis Congenita; Telomere; Nuclear Proteins; RNA; Mutation; RNA-Binding Proteins; Cell Cycle Proteins; Intracellular Signaling Peptides and Proteins
PubMed: 37879098
DOI: 10.1093/hmg/ddad180 -
Arab Journal of Gastroenterology : the... Aug 2023Previous studies have suggested that lncRNAs impact cancer progression. The lncRNA AC125611.3 (also referred to as RP11-161H23.5) is highly expressed in colon cancer but...
BACKGROUND AND STUDY AIMS
Previous studies have suggested that lncRNAs impact cancer progression. The lncRNA AC125611.3 (also referred to as RP11-161H23.5) is highly expressed in colon cancer but rarely studied; understanding its regulation may provide novel insights on treating colon cancer.
MATERIALS AND METHODS
qRT-PCR was performed to quantify RNAs. CCK-8 and EdU assays were performed to assess cell proliferation. Western blot analysis was used to detect levels of proteins related to cell apoptosis and EMT. Wound healing assay and Transwell invasion assay were conducted to evaluate cell migratory and invasive capabilities, respectively. Luciferase reporter assay, RIP assay, and pull-down assay were used to verify RNA-RNA and RNA-protein interactions.
RESULTS
AC125611.3 was highly overexpressed in colon cancer cells. AC125611.3 depletion curbed cell proliferative, invasive, migratory, and EMT processes while enhancing apoptosis. Furthermore, AC125611.3 activated the Wnt signaling pathway in colon cancer cells by regulating catenin beta-1 (CTNNB1). Moreover, AC125611.3 recruited dyskeratosis congenita 1 (DKC1) to stabilize CTNNB1.
CONCLUSION
AC125611.3 recruits DKC1 to stabilize CTNNB1 and activate Wnt signaling, thereby promoting the progression of colon cancer.
Topics: Humans; Cell Line, Tumor; Dyskeratosis Congenita; Colonic Neoplasms; Wnt Signaling Pathway; RNA, Long Noncoding; Gene Expression Regulation, Neoplastic; Nuclear Proteins; Cell Cycle Proteins; beta Catenin
PubMed: 37684150
DOI: 10.1016/j.ajg.2022.10.013 -
BioRxiv : the Preprint Server For... Mar 2024Telomeres protect chromosome ends and determine the replication potential of dividing cells. The canonical telomere sequence TTAGGG is synthesized by telomerase...
Telomeres protect chromosome ends and determine the replication potential of dividing cells. The canonical telomere sequence TTAGGG is synthesized by telomerase holoenzyme, which maintains telomere length in proliferative stem cells. Although the core components of telomerase are well-defined, mechanisms of telomerase regulation are still under investigation. We report a novel role for the Src family kinase Fyn, which disrupts telomere maintenance in stem cells by phosphorylating the scaffold protein Menin. We found that Fyn knockdown prevented telomere erosion in human and mouse stem cells, validating the results with four telomere measurement techniques. We show that Fyn phosphorylates Menin at tyrosine 603 (Y603), which increases Menin's SUMO1 modification, C-terminal stability, and importantly, its association with the telomerase RNA component (TR). Using mass spectrometry, immunoprecipitation, and immunofluorescence experiments we found that SUMO1-Menin decreases TR's association with telomerase subunit Dyskerin, suggesting that Fyn's phosphorylation of Menin induces telomerase subunit mislocalization and may compromise telomerase function at telomeres. Importantly, we find that Fyn inhibition reduces accelerated telomere shortening in human iPSCs harboring mutations for dyskeratosis congenita.
PubMed: 37873235
DOI: 10.1101/2023.10.04.560876 -
Human Molecular Genetics Mar 2024Telomeres are nucleoprotein structures that protect the chromosome ends from degradation and fusion. Telomerase is a ribonucleoprotein complex essential to maintain the...
Telomeres are nucleoprotein structures that protect the chromosome ends from degradation and fusion. Telomerase is a ribonucleoprotein complex essential to maintain the length of telomeres. Germline defects that lead to short and/or dysfunctional telomeres cause telomere biology disorders (TBDs), a group of rare and heterogeneous Mendelian diseases including pulmonary fibrosis, dyskeratosis congenita, and Høyeraal-Hreidarsson syndrome. TPP1, a telomeric factor encoded by the gene ACD, recruits telomerase at telomere and stimulates its activity via its TEL-patch domain that directly interacts with TERT, the catalytic subunit of telomerase. TBDs due to TPP1 deficiency have been reported only in 11 individuals. We here report four unrelated individuals with a wide spectrum of TBD manifestations carrying either heterozygous or homozygous ACD variants consisting in the recurrent and previously described in-frame deletion of K170 (K170∆) and three novel missense mutations G179D, L184R, and E215V. Structural and functional analyses demonstrated that the four variants affect the TEL-patch domain of TPP1 and impair telomerase activity. In addition, we identified in the ACD gene several motifs associated with small deletion hotspots that could explain the recurrence of the K170∆ mutation. Finally, we detected in a subset of blood cells from one patient, a somatic TERT promoter-activating mutation that likely provides a selective advantage over non-modified cells, a phenomenon known as indirect somatic genetic rescue. Together, our results broaden the genetic and clinical spectrum of TPP1 deficiency and specify new residues in the TEL-patch domain that are crucial for length maintenance and stability of human telomeres in vivo.
Topics: Humans; Biology; Mutation; Shelterin Complex; Telomerase; Telomere; Telomere-Binding Proteins
PubMed: 38176734
DOI: 10.1093/hmg/ddad210 -
Communications Chemistry Nov 2023The Shelterin complex protein TPP1 interacts with human telomerase (TERT) by means of the TEL-patch region, controlling telomere homeostasis. Aberrations in the...
The Shelterin complex protein TPP1 interacts with human telomerase (TERT) by means of the TEL-patch region, controlling telomere homeostasis. Aberrations in the TPP1-TERT heterodimer formation might lead to short telomeres and severe diseases like dyskeratosis congenita and Hoyeraal-Hreidarsson syndrome. In the present study, we provide a thorough characterization of the structural properties of the TPP1's OB-domain by combining data coming from microsecond-long molecular dynamics calculations, time-series analyses, and graph-based networks. Our results show that the TEL-patch conformational freedom is influenced by a network of long-range amino acid communications that together determine the proper TPP1-TERT binding. Furthermore, we reveal that in TPP1 pathological variants Glu169Δ, Lys170Δ and Leu95Gln, the TEL-patch plasticity is reduced, affecting the correct binding to TERT and, in turn, telomere processivity, which eventually leads to accelerated aging of affected cells. Our study provides a structural basis for the design of TPP1-targeting ligands with therapeutic potential against cancer and telomeropathies.
PubMed: 37935941
DOI: 10.1038/s42004-023-01040-y -
International Journal of Molecular... Apr 2024We explore the possibility that defects in genes associated with the response and repair of DNA double strand breaks predispose oral potentially malignant disorders... (Review)
Review
We explore the possibility that defects in genes associated with the response and repair of DNA double strand breaks predispose oral potentially malignant disorders (OPMD) to undergo malignant transformation to oral squamous cell carcinoma (OSCC). Defects in the homologous recombination/Fanconi anemia (HR/FA), but not in the non-homologous end joining, causes the DNA repair pathway to appear to be consistent with features of familial conditions that are predisposed to OSCC (FA, Bloom's syndrome, Ataxia Telangiectasia); this is true for OSCC that occurs in young patients, sometimes with little/no exposure to classical risk factors. Even in Dyskeratosis Congenita, a disorder of the telomerase complex that is also predisposed to OSCC, attempts at maintaining telomere length involve a pathway with shared HR genes. Defects in the HR/FA pathway therefore appear to be pivotal in conditions that are predisposed to OSCC. There is also some evidence that abnormalities in the HR/FA pathway are associated with malignant transformation of sporadic cases OPMD and OSCC. We provide data showing overexpression of HR/FA genes in a cell-cycle-dependent manner in a series of OPMD-derived immortal keratinocyte cell lines compared to their mortal counterparts. The observations in this study argue strongly for an important role of the HA/FA DNA repair pathway in the development of OSCC.
Topics: Humans; Mouth Neoplasms; Carcinoma, Squamous Cell; Squamous Cell Carcinoma of Head and Neck; Fanconi Anemia; Head and Neck Neoplasms; DNA
PubMed: 38612901
DOI: 10.3390/ijms25074092 -
QJM : Monthly Journal of the... Jul 2023
Topics: Humans; Dyskeratosis Congenita; Idiopathic Noncirrhotic Portal Hypertension; Hypertension, Portal; Nuclear Proteins; Ribonucleoproteins, Small Nuclear
PubMed: 36943377
DOI: 10.1093/qjmed/hcad039