Werner Syndrome Research Articles

Optical coherence tomography findings in three patients with Werner syndrome

BackgroundWerner syndrome is a rare, autosomal recessive disorder characterised by premature aging. It is a typical hereditary progeroid syndrome that can be difficult to diagnose owing to its rarity and the similarity of some of its symptoms, such as juvenile cataracts, to other common ophthalmologic conditions. Early onset of bilateral cataracts is currently used as the ophthalmological feature for Werner syndrome; however, ophthalmologists often find performing a detailed examination of the medical history and genetic testing for Werner syndrome at the time of an ophthalmologic consultation challenging. If a unique ocular finding was observed on ocular examinations in cases of juvenile bilateral cataracts, we could consider Werner syndrome as a differential diagnosis. Case presentationWe documented the cases of three patients with Werner syndrome in whom thinning of the retina in the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) were observed using optical coherence tomography (OCT). Visual field tests revealed the loss of visual field mainly owing to glaucoma.The thinnig of the choroidal thickness (CT) in three patients was also observed using enhanced depth imaging (EDI)-OCT.ConclusionsThree patients have thinning of the RNFL, GCC, and choroidal thickness and the loss of visual field. These findings suggest the need for including Werner syndrome in the differential diagnosis when patients presenting with juvenile cataracts of unknown cause also show abnormal retinal and choroidal thinning in the OCT images.

Interstitial lung disease in a patient with premature aging: Suspected Werner syndrome

Werner syndrome (WS) is a rare inherited autosomal recessive disease that can be diagnosed with cardinal signs without the genetic testing. Some features that are consistent with WS include premature aging, loss, and graying hair, scleroderma-like skin changes. We report a 42-year-old man with cardinal signs of WS who also developed interstitial lung disease (ILD). The patient had past medical history (PMHx) of atypical left femur fracture in his early 30s from unknown causes. Also, he had loss and graying hair, salt-on-pepper skin changes, associated with squeaky voice, muscle wasting, and osteoporosis. He had worsening symptoms of dyspnea on exertion and was found with bilateral diffuse subpleural reticular opacities with slight mid- to lower-lung predominance and mild bronchiectasis without honeycombing or ground-glass airspace opacities on chest computed tomography (CT) scan. Other causes of ILD were excluded as patient routine laboratories and rheumatologic workup was negative. Werner syndrome presents similar features with other telomerase-associated diseases such as mutations of telomerase complexes [telomerase RNA component (TERC) and telomerase reverse transcriptase (TERT)]. Werner syndrome can be difficult to diagnose because it is a rare genetic disease that begins to show symptoms and signs after 10 or 20-year-olds, but the diagnosis is recognized after 30s. Few cases have been reported about the association of WS and ILD, but both diseases are aging diseases. This case might be the first case reported in Puerto Rico of Werner syndrome associated with ILD. Early referral and treatment is important to improve patients’ quality of life and life expectancy by slowing the progression of the disease.

Research on Werner Syndrome: Trends from Past to Present and Future Prospects.

A rare and autosomal recessive premature aging disorder, Werner syndrome (WS) is characterized by the early onset of aging-associated diseases, including shortening stature, alopecia, bilateral cataracts, skin ulcers, diabetes, osteoporosis, arteriosclerosis, and chromosomal instability, as well as cancer predisposition. WRN, the gene responsible for WS, encodes DNA helicase with a 3′ to 5′ exonuclease activity, and numerous studies have revealed that WRN helicase is involved in the maintenance of chromosome stability through actions in DNA, e.g., DNA replication, repair, recombination, and epigenetic regulation via interaction with DNA repair factors, telomere-binding proteins, histone modification enzymes, and other DNA metabolic factors. However, although these efforts have elucidated the cellular functions of the helicase in cell lines, they have not been linked to the treatment of the disease. Life expectancy has improved for WS patients over the past three decades, and it is hoped that a fundamental treatment for the disease will be developed. Disease-specific induced pluripotent stem (iPS) cells have been established, and these are expected to be used in drug discovery and regenerative medicine for WS patients. In this article, we review trends in research to date and present some perspectives on WS research with regard to the application of pluripotent stem cells. Furthermore, the elucidation of disease mechanisms and drug discovery utilizing the vast amount of scientific data accumulated to date will be discussed.

Peripheral neuropathies associated with DNA repair disorders.

Repair of genomic DNA is a fundamental housekeeping process that quietly maintains the health of our genomes. The consequences of a genetic defect affecting a component of this delicate mechanism are quite harmful, characterized by a cascade of premature aging that injures a variety of organs, including the nervous system. One part of the nervous system that is impaired in certain DNA repair disorders is the peripheral nerve. Chronic motor, sensory, and sensorimotor polyneuropathies have all been observed in affected individuals, with specific physiologies associated with different categories of DNA repair disorders. Cockayne syndrome has classically been linked to demyelinating polyneuropathies, whereas xeroderma pigmentosum has long been associated with axonal polyneuropathies. Three additional recessive DNA repair disorders are associated with neuropathies, including trichothiodystrophy, Werner syndrome, and ataxia-telangiectasia. Although plausible biological explanations exist for why the peripheral nerves are specifically vulnerable to impairments of DNA repair, specific mechanisms such as oxidative stress remain largely unexplored in this context, and bear further study. It is also unclear why different DNA repair disorders manifest with different types of neuropathy, and why neuropathy is not universally present in those diseases. Longitudinal physiological monitoring of these neuropathies with serial electrodiagnostic studies may provide valuable noninvasive outcome data in the context of future natural history studies, and thus the responses of these neuropathies may become sentinel outcome measures for future clinical trials of treatments currently in development such as adeno-associated virus gene replacement therapies.

WRN promotes bone development and growth by unwinding SHOX-G-quadruplexes via its helicase activity in Werner Syndrome

Werner Syndrome (WS) is an autosomal recessive disorder characterized by premature aging due to mutations of the WRN gene. A classical sign in WS patients is short stature, but the underlying mechanisms are not well understood. Here we report that WRN is indispensable for chondrogenesis, which is the engine driving the elongation of bones and determines height. Zebrafish lacking wrn exhibit impairment of bone growth and have shorter body stature. We pinpoint the function of WRN to its helicase domain. We identify short-stature homeobox (SHOX) as a crucial and direct target of WRN and find that the WRN helicase core regulates the transcriptional expression of SHOX via unwinding G-quadruplexes. Consistent with this, shox−/− zebrafish exhibit impaired bone growth, while genetic overexpression of SHOX or shox expression rescues the bone developmental deficiency induced in WRN/wrn-null mutants both in vitro and in vivo. Collectively, we have identified a previously unknown function of WRN in regulating bone development and growth through the transcriptional regulation of SHOX via the WRN helicase domain, thus illuminating a possible approach for new therapeutic strategies.

WRN rescues replication forks compromised by a BRCA2 deficiency: Predictions for how inhibition of a helicase that suppresses premature aging tilts the balance to fork demise and chromosomal instability in cancer.

Hereditary breast and ovarian cancers are frequently attributed to germline mutations in the tumor suppressor genes BRCA1 and BRCA2. BRCA1/2 act to repair double-strand breaks (DSBs) and suppress the demise of unstable replication forks. Our work elucidated a dynamic interplay between BRCA2 and the WRN DNA helicase/exonuclease defective in the premature aging disorder Werner syndrome. WRN and BRCA2 participate in complementary pathways to stabilize replication forks in cancer cells, allowing them to proliferate. Whether the functional overlap of WRN and BRCA2 is relevant to replication at gaps between newly synthesized DNA fragments, protection of telomeres, and/or metabolism of secondary DNA structures remain to be determined. Advances in understanding the mechanisms elicited during replication stress have prompted the community to reconsider avenues for cancer therapy. Insights from studies of PARP or topoisomerase inhibitors provide working models for the investigation of WRN's mechanism of action. We discuss these topics, focusing on the implications of the WRN-BRCA2 genetic interaction under conditions of replication stress.

Partial lipodystrophy, severe dyslipidaemia and insulin resistant diabetes as early signs of Werner syndrome

Werner syndrome is a premature ageing disorder caused by biallelic variants in the WRN gene. WRN encodes a dual DNA helicase/exonuclease enzyme. Molecular diagnosis is commonly only made at a late disease stage in the third or fourth decade, when cardinal features have become apparent. We describe a 28 year-old woman who presented with early onset diabetes associated with partial lipodystrophy, severe dyslipidaemia and rapidly progressive liver fibrosis related to non-alcoholic steatohepatitis in the absence of progeroid features. Werner syndrome was diagnosed by trio exome analysis, which revealed compound heterozygous WRN mutations: the known variant c.1290_1293del (p.Asn430Lysfs*7) and the novel intronic splice site variant c.2732+5G>A. cDNA analysis demonstrated this to lead to in-frame skipping of exon 22, predicted to delete most of the zinc binding region of the helicase domain. We suggest that including the WRN gene in genetic analysis of early onset diabetes, lipodystrophy or dyslipidaemia would allow for the opportunity to diagnose some cases of Werner syndrome long before clinical criteria are met, thereby allowing early implementation of important primary prevention interventions.

Turning up the NAD+-mitophagy axis to treat Alzheimer's disease.

Turning up the NAD+-mitophagy axis to treat Alzheimer's disease.

147-OR: Glucose Intolerance of Hereditary Progeria Werner Syndrome and Cellular Senescence in Their Adipose Tissue

Background: Werner syndrome (WS) is a hereditary premature aging disorder in which various signs of accelerated aging develop after puberty. These signs include gray hair, cataracts, diabetes, myocardial infarction, and malignant tumors. Patients with WS frequently show severe insulin resistance, visceral fat accumulation, and subcutaneous fat atrophy, leading to myocardial infarction due to atherosclerosis. However, the mechanism of accelerated aging and its effect on adipose tissue dysfunction and glucose intolerance remain unclear. Materials and Methods: We evaluated visceral fat area and insulin resistance using the glucose clamp method in four Japanese patients with WS. Stromal vascular fraction (SVF) was obtained from the subcutaneous adipose tissue of WS patients (WSVF) . Healthy individuals and phenotypes were examined. Results: The median glucose infusion rate (GIR) was 3.78 mg/kg/min (interquartile range 3.05, 4.25; insulin infusion rate=1.25 mU/kg/min; normal range >6 mg/kg/min) . All Japanese patients showed severe insulin resistance, sarcopenia, and visceral fat accumulation. The visceral fat area and GIR were inversely correlated (R2=0.72) . In vitro analysis of WSVF revealed early replicative senescence and an increase in SAβgal staining. A significant increase was observed in the expression of senescence-associated secretory phenotypes (SASP) , such as IL1B, IL6, and CXCL8 (p<0.01) , and the senescence marker CDKN2A (p=0.094) . RNA-seq analysis showed that genes related to cell adhesion and cell structure were upregulated in WSVF, whereas genes related to chromosomes, nuclear division, and cell cycle were downregulated. Adipose differentiation was suppressed in WSVF. Conclusions: SVF from the adipose tissue of WS patients exhibited cellular senescence and increased inflammatory cytokine production. Cellular senescence and chronic inflammation of adipose tissue induced by SASP may exacerbate insulin resistance in WS patients. Disclosure D.Sawada: None. T.Takatani: None. H.Hamada: None. K.Yokote: None. H.Kato: n/a. Y.Maezawa: None. D.Kinoshita: None. S.Funayama: None. H.Kaneko: None. T.Minamizuka: None. M.Koshizaka: None. T.Shiohama: None. Funding JSPS (20K17485) , AMED (21bm0804016h0005)

XPG in the Nucleotide Excision Repair and Beyond: a study on the different functional aspects of XPG and its associated diseases.

Several proteins are involved in DNA repair mechanisms attempting to repair damages to the DNA continuously. One such protein is Xeroderma Pigmentosum Complementation Group G (XPG), a significant component in the Nucleotide Excision Repair (NER) pathway. XPG is accountable for making the 3' incision in the NER, while XPF-ERCC4 joins ERCC1 to form the XPF-ERCC1 complex. This complex makes a 5' incision to eliminate bulky DNA lesions. XPG is also known to function as a cofactor in the Base Excision Repair (BER) pathway by increasing hNth1 activity, apart from its crucial involvement in the NER. Reports suggest that XPG also plays a non-catalytic role in the Homologous Recombination Repair (HRR) pathway by forming higher-order complexes with BRCA1, BRCA2, Rad51, and PALB2, further influencing the activity of these molecules. Studies show that, apart from its vital role in repairing DNA damages, XPG is also responsible for R-loop formation, which facilitates exhibiting phenotypes of Werner Syndrome. Though XPG has a role in several DNA repair pathways and molecular mechanisms, it is primarily a NER protein. Unrepaired and prolonged DNA damage leads to genomic instability and facilitates neurological disorders, aging, pigmentation, and cancer susceptibility. This review explores the vital role of XPG in different DNA repair mechanisms which are continuously involved in repairing these damaged sites and its failure leading to XP-G, XP-G/CS complex phenotypes, and cancer progression.

Non-enzymatic function of WRN RECQL helicase regulates removal of topoisomerase-I-DNA covalent complexes and triggers NF-κB signaling in cancer.

Mutation in Werner (WRN) RECQL helicase is associated with premature aging syndrome (Werner syndrome, WS) and predisposition to multiple cancers. In patients with solid cancers, deficiency of the WRN RECQL helicase is paradoxically associated with enhanced overall survival in response to treatment with TOP1 inhibitors, which stabilize pathological TOP1‐DNA‐covalent‐complexes (TOP1cc) on the genome. However, the underlying mechanism of WRN in development of chemoresistance to TOP1 inhibitors is not yet explored. Our whole‐genome transcriptomic analysis for ~25,000 genes showed robust activation of NF‐κB‐dependent prosurvival genes in response to TOP1cc. CRISPR‐Cas9 knockout, shRNA silencing, and under‐expression of WRN confer high‐sensitivity of multiple cancers to TOP1 inhibitor. We demonstrated that WRN orchestrates TOP1cc repair through proteasome‐dependent and proteasome‐independent process, unleashing robust ssDNA generation. This in turn ensues signal transduction for CHK1 mediated NF‐κB‐activation through IκBα‐degradation and nuclear localization of p65 protein. Intriguingly, our site‐directed mutagenesis and rescue experiments revealed that neither RECQL‐helicase nor DNA‐exonuclease enzyme activity of WRN (WRNE84A, WRNK577M, and WRNE84A‐K577M) were required for TOP1cc removal, ssDNA generation and signaling for NF‐κB activation. In correlation with patient data and above results, the TOP1 inhibitor‐based targeted therapy showed that WRN‐deficient melanoma tumors were highly sensitive to TOP1 inhibition in preclinical in vivo mouse model. Collectively, our findings identify hitherto unknown non‐enzymatic role of WRN RECQL helicase in pathological mechanisms underlying TOP1cc processing and subsequent NF‐κB‐activation, offering a potential targeted therapy for WRN‐deficient cancer patients.

Targeted long-read sequencing identifies missing pathogenic variants in unsolved Werner syndrome cases

BackgroundWerner syndrome (WS) is an autosomal recessive progeroid syndrome caused by variants in WRN. The International Registry of Werner Syndrome has identified biallelic pathogenic variants in 179/188 cases of classical...

Radiotherapy and radiosensitivity syndromes in DNA repair gene mutations.

Ionizing radiation DNA damage is the main mechanism of radiotherapy (RT) action and the outcome of treatment and healthy tissue toxicity is influenced by a number of external and internal factors, including mutations in DNA damage recognition and repair. Disorders of DNA repair may result in increased sensitivity to cancer treatment. The mechanism of DNA repair and an overview of genetic syndromes with mutations in genes involved in DNA repair clarify the accelerated carcinogenesis and increased radiosensitivity in RT cancers. Most radiosensitivity syndromes are autosomal recessively inherited; examples are ataxia teleangiectasia, Nijmegen breakage syndrome, xeroderma pigmentosum, Cockayne syndrome, Bloom syndrome and Werner syndrome. Radiotherapy is contraindicated in most homozygous patients with recessive radiosensitivity syndromes. Asymptomatic heterozygotes may have an increased risk of tumor incidence and a small part of them slightly increased risk of RT intolerance; however, this does not limit RT treatment. The high risk of secondary malignancies after radiotherapy is a contraindication to adjuvant RT in Li-Fraumeni syndrome.

Treatment of osteoporosis associated with Werner syndrome: A three‐case report

Treatment of osteoporosis associated with Werner syndrome: A three‐case report

A high prevalence of myeloid malignancies in progeria with Werner syndrome is associated with p53 insufficiency

Werner syndrome (WS) is a progeroid syndrome caused by mutations in the WRN gene, which encodes the RecQ type DNA helicase for the unwinding of unusual DNA structures and is implicated in DNA replication, DNA repair, and telomere maintenance. patients with WS are prone to develop malignant neoplasms, including hematological malignancies. However, the pathogenesis of WS-associated hematological malignancies remains uncharacterized. Here we investigated the somatic gene mutations in WS-associated myelodysplastic syndrome/acute myeloid leukemia (MDS/AML). Whole-exome sequencing (WES) of 4 patients with WS with MDS/AML revealed that all patients had somatic mutations in TP53 but no other recurrent mutations in MDS/AML. TP53 mutations were identified at low allele frequencies at more than one year before the MDS/AML stage. All 4 patients had complex chromosomal abnormalities including those that involved TP53. Targeted sequencing of nine patients with WS without apparent blood abnormalities did not detect recurrent mutations in MDS/AML except for a PPM1D mutation. These results suggest that patients with WS are apt to acquire TP53 mutations and/or chromosomal abnormalities involving TP53, rather than other MDS/AML-related mutations. TP53 mutations are frequently associated with prior exposure to chemotherapy; however, all four patients with WS with TP53 mutations/deletions had not received any prior chemotherapy, suggesting a pathogenic link between WRN mutations and p53 insufficiency. These results indicate that WS hematopoietic stem cells with WRN insufficiency acquire competitive fitness by inactivating p53, which may cause complex chromosomal abnormalities and the subsequent development of myeloid malignancies. These findings promote our understanding of the pathogenesis of myeloid malignancies associated with progeria.

RecQ-helicase processing of G-rich DNA

The Werner syndrome ATP-dependent helicase (WRN) is part of the RecQ helicase family responsible for DNA maintenance. WRN's localization at telomeres during S-phase is enhanced upon replicative stress, and it is believed that WRN is responsible for resolving certain secondary DNA structures forming at telomeres and stalled replication forks. One of these structures is the G-quadruplex, which forms in guanine-rich DNA with various topological conformations, and might act as a roadblock for DNA maintenance proteins.

R-Loop-Associated Genomic Instability and Implication of WRN and WRNIP1.

Maintenance of genome stability is crucial for cell survival and relies on accurate DNA replication. However, replication fork progression is under constant attack from different exogenous and endogenous factors that can give rise to replication stress, a source of genomic instability and a notable hallmark of pre-cancerous and cancerous cells. Notably, one of the major natural threats for DNA replication is transcription. Encounters or conflicts between replication and transcription are unavoidable, as they compete for the same DNA template, so that collisions occur quite frequently. The main harmful transcription-associated structures are R-loops. These are DNA structures consisting of a DNA–RNA hybrid and a displaced single-stranded DNA, which play important physiological roles. However, if their homeostasis is altered, they become a potent source of replication stress and genome instability giving rise to several human diseases, including cancer. To combat the deleterious consequences of pathological R-loop persistence, cells have evolved multiple mechanisms, and an ever growing number of replication fork protection factors have been implicated in preventing/removing these harmful structures; however, many others are perhaps still unknown. In this review, we report the current knowledge on how aberrant R-loops affect genome integrity and how they are handled, and we discuss our recent findings on the role played by two fork protection factors, the Werner syndrome protein (WRN) and the Werner helicase-interacting protein 1 (WRNIP1) in response to R-loop-induced genome instability.

Paradoxical role of the major DNA repair protein, OGG1, in action-at-a-distance mutation induction by 8-oxo-7,8-dihydroguanine

Oxidatively damaged bases induce mutations and are involved in cancer initiation. 8-Oxo-7,8-dihydroguanine (G°, 8-hydroxyguanine) is an abundant oxidized base that induces targeted G:C→T:A transversions in human cells, as well as untargeted base substitution (action-at-a-distance) mutations of the G bases of 5′-GpA-3′ dinucleotides. The action-at-a-distance mutations become more frequent than the targeted transversions when the amount of Werner syndrome (WRN) protein is decreased. In this study, OGG1, the major DNA glycosylase for the damaged base, and WRN were knocked down in isolation and in combination in human U2OS cells, and a shuttle plasmid carrying G° was introduced into the knockdown cells. Interestingly, fewer action-at-a-distance mutations were observed in the WRN plus OGG1 double knockdown cells, as compared to the WRN single knockdown cells. These results indicated the paradoxical role of OGG1, as an accelerator of the action-at-a-distance mutations by the oxidized guanine base.

DNA methylation signatures in Blood DNA of Hutchinson-Gilford Progeria syndrome.

Hutchinson–Gilford Progeria Syndrome (HGPS) is an extremely rare genetic disorder caused by mutations in the LMNA gene and characterized by premature and accelerated aging beginning in childhood. In this study, we performed the first genome‐wide methylation analysis on blood DNA of 15 patients with progeroid laminopathies using Infinium Methylation EPIC arrays including 8 patients with classical HGPS. We could observe DNA methylation alterations at 61 CpG sites as well as 32 significant regions following a 5 Kb tiling analysis. Differentially methylated probes were enriched for phosphatidylinositol biosynthetic process, phospholipid biosynthetic process, sarcoplasm, sarcoplasmic reticulum, phosphatase regulator activity, glycerolipid biosynthetic process, glycerophospholipid biosynthetic process, and phosphatidylinositol metabolic process. Differential methylation analysis at the level of promoters and CpG islands revealed no significant methylation changes in blood DNA of progeroid laminopathy patients. Nevertheless, we could observe significant methylation differences in classic HGPS when specifically looking at probes overlapping solo‐WCGW partially methylated domains. Comparing aberrantly methylated sites in progeroid laminopathies, classic Werner syndrome, and Down syndrome revealed a common significantly hypermethylated region in close vicinity to the transcription start site of a long non‐coding RNA located anti‐sense to the Catenin Beta Interacting Protein 1 gene (CTNNBIP1). By characterizing epigenetically altered sites, we identify possible pathways/mechanisms that might have a role in the accelerated aging of progeroid laminopathies.

Bilateral sequential manual small incision cataract surgery as the management of phacomorphic glaucoma in a rare case of Werner's syndrome

We present a case of Werner's syndrome (WS), which is a rare progressive hereditary disorder characterized by accelerated aging. Bilateral cataracts are one of the cardinal signs of WS. The clinical characteristics of our patient met the diagnostic criteria of “Probable WS” according to the International Registry of Werner Syndrome. Our patient presented with bilateral phacomorphic glaucoma. Previous reports involving single case of WS, cataract surgery was performed by clear corneal phacoemulsification. Our patient underwent immediate bilateral sequential manual small incision cataract surgery (IBSCS) with intraocular lens implantation. We highlight the fact that bilateral cataract surgery with Manual small incision cataract surgery (M-SICS) for phacomorphic glaucoma is a safe choice for patients with Werner's syndrome.