Werner Syndrome Research Articles

C. elegans orthologs MUT-7/CeWRN-1 of Werner syndrome protein regulate neuronal plasticity.

Caenorhabditis elegans expresses human Werner syndrome protein (WRN) orthologs as two distinct proteins: MUT-7, with a 3'-5' exonuclease domain, and CeWRN-1, with helicase domains. How these domains cooperate remains unclear. Here, we demonstrate the different contributions of MUT-7 and CeWRN-1 to 22G small interfering RNA (siRNA) synthesis and the plasticity of neuronal signaling. MUT-7 acts specifically in the cytoplasm to promote siRNA biogenesis and in the nucleus to associate with CeWRN-1. The import of siRNA by the nuclear Argonaute NRDE-3 promotes the loading of the heterochromatin-binding protein HP1 homolog HPL-2 onto specific loci. This heterochromatin complex represses the gene expression of the guanylyl cyclase ODR-1 to direct olfactory plasticity in C. elegans. Our findings suggest that the exonuclease and helicase domains of human WRN may act in concert to promote RNA-dependent loading into a heterochromatin complex, and the failure of this entire process reduces plasticity in postmitotic neurons.

Human RecQ Helicases in DNA Double-Strand Break Repair.

RecQ DNA helicases are a conserved protein family found in bacteria, fungus, plants, and animals. These helicases play important roles in multiple cellular functions, including DNA replication, transcription, DNA repair, and telomere maintenance. Humans have five RecQ helicases: RECQL1, Bloom syndrome protein (BLM), Werner syndrome helicase (WRN), RECQL4, and RECQL5. Defects in BLM and WRN cause autosomal disorders: Bloom syndrome (BS) and Werner syndrome (WS), respectively. Mutations in RECQL4 are associated with three genetic disorders, Rothmund–Thomson syndrome (RTS), Baller–Gerold syndrome (BGS), and RAPADILINO syndrome. Although no genetic disorders have been reported due to loss of RECQL1 or RECQL5, dysfunction of either gene is associated with tumorigenesis. Multiple genetically independent pathways have evolved that mediate the repair of DNA double-strand break (DSB), and RecQ helicases play pivotal roles in each of them. The importance of DSB repair is supported by the observations that defective DSB repair can cause chromosomal aberrations, genomic instability, senescence, or cell death, which ultimately can lead to premature aging, neurodegeneration, or tumorigenesis. In this review, we will introduce the human RecQ helicase family, describe in detail their roles in DSB repair, and provide relevance between the dysfunction of RecQ helicases and human diseases.

Fibroblasts from different body parts exhibit distinct phenotypes in adult progeria Werner syndrome.

Werner syndrome (WS), also known as adult progeria, is characterized by accelerated aging symptoms from a young age. Patients with WS experience painful intractable skin ulcers with calcifications in their extremities, subcutaneous lipoatrophy, and sarcopenia. However, there is no significant abnormality in the trunk skin, where the subcutaneous fat relatively accumulates. The cause of such differences between the limbs and trunk is unknown. To investigate the underlying mechanism behind these phenomena, we established and analyzed dermal fibroblasts from the foot and trunk of two WS patients. As a result, WS foot-derived fibroblasts showed decreased proliferative potential compared to that from the trunk, which correlated with the telomere shortening. Transcriptome analysis showed increased expression of genes involved in osteogenesis in the foot fibroblasts, while adipogenic and chondrogenic genes were downregulated in comparison with the trunk. Consistent with these findings, the adipogenic and chondrogenic differentiation capacity was significantly decreased in the foot fibroblasts in vitro. On the other hand, the osteogenic potential was mutually maintained and comparable in the foot and trunk fibroblasts. These distinct phenotypes in the foot and trunk fibroblasts are consistent with the clinical symptoms of WS and may partially explain the underlying mechanism of this disease phenotype.

Pharmacological targeting of differential DNA repair, radio-sensitizes WRN-deficient cancer cells in vitro and in vivo

Werner (WRN) expression is epigenetically downregulated in various tumors. It is imperative to understand differential repair process in WRN-proficient and WRN-deficient cancers to find pharmacological targets for radio-sensitization of WRN-deficient cancer. In the current investigation, we showed that pharmacological inhibition of CHK1 mediated homologous recombination repair (HRR), but not non-homologous end joining (NHEJ) repair, can causes hyper-radiosensitization of WRN-deficient cancers. This was confirmed in cancer cell lines of different tissue origin (osteosarcoma, colon adenocarcinoma and melanoma) with WRN silencing and overexpression. We established that WRN-depleted cells are dependent on a critical but compromised CHK1-mediated HRR-pathway for repairing ionizing radiation (IR) induced DSBs for their survival. Mechanistically, we unraveled a new finding that the MRE11, CTIP and WRN proteins are largely responsible for resections of late and persistent DSBs. In response to IR-treatment, MRE11 and CTIP-positively and WRN-negatively regulate p38-MAPK reactivation in a CHK1-dependent manner. A degradation resistant WRN protein, mutated at serine 1141, abrogates p38-MAPK activation. We also showed that CHK1-p38-MAPK axis plays important role in RAD51 mediated HRR in WRN-silenced cells. Like CHK1 inhibition, pharmacological-inhibition of p38-MAPK also hyper-radiosensitizes WRN-depleted cells by targeting HR-pathway. Combination treatment of CHK1-inhibitor (currently under various clinical trials) and IR exhibited a strong synergy against WRN-deficient melanoma tumor in vivo. Taken together, our findings suggest that pharmacological targeting of CHK1-p38-MAPK mediated HRR is an attractive strategy for enhancing therapeutic response of radiation treatment of cancer.

The Distinct Function of p21Waf1/Cip1 With p16Ink4a in Modulating Aging Phenotypes of Werner Syndrome by Affecting Tissue Homeostasis

Human Werner syndrome (WS) is an autosomal recessive progeria disease. A mouse model of WS manifests the disease through telomere dysfunction-induced aging phenotypes, which might result from cell cycle control and cellular senescence. Both p21Waf1/Cip1 (p21, encoded by the Cdkn1a gene) and p16Ink4a (p16, encoded by the Ink4a gene) are cell cycle inhibitors and are involved in regulating two key pathways of cellular senescence. To test the effect of p21 and p16 deficiencies in WS, we crossed WS mice (DKO) with p21–/– or p16–/– mice to construct triple knockout (p21-TKO or p16-TKO) mice. By studying the survival curve, bone density, regenerative tissue (testis), and stem cell capacity (intestine), we surprisingly found that p21-TKO mice displayed accelerated premature aging compared with DKO mice, while p16-TKO mice showed attenuation of the aging phenotypes. The incidence of apoptosis and cellular senescence were upregulated in p21-TKO mice tissue and downregulated in p16-TKO mice. Surprisingly, cellular proliferation in p21-TKO mice tissue was also upregulated, and the p21-TKO mice did not show telomere shortening compared with age-matched DKO mice, although p16-TKO mice displayed obvious enhancement of telomere lengthening. Consistent with these phenotypes, the SIRT1-PGC1 pathway was upregulated in p16-TKO but downregulated in p21-TKO compared with DKO mouse embryo fibroblasts (MEFs). However, the DNA damage response pathway was highly activated in p21-TKO, but rescued in p16-TKO, compared with DKO MEFs. These data suggest that p21 protected the stem cell reservoir by regulating cellular proliferation and turnover at a proper rate and that p21 loss in WS activated fairly severe DNA damage responses (DDR), which might cause an abnormal increase in tissue homeostasis. On the other hand, p16 promoted cellular senescence by inhibiting cellular proliferation, and p16 deficiency released this barrier signal without causing severe DDR.

Revealing the Potential Application of EC-Synthetic Retinoid Analogues in Anticancer Therapy.

(1) Background and Aim: All-trans retinoic acid (ATRA) induces differentiation and inhibits growth of many cancer cells. However, resistance develops rapidly prompting the urgent need for new synthetic and potent derivatives. EC19 and EC23 are two synthetic retinoids with potent stem cell neuro-differentiation activity. Here, these compounds were screened for their in vitro antiproliferative and cytotoxic activity using an array of different cancer cell lines. (2) Methods: MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, AV/PI (annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI)), cell cycle analysis, immunocytochemistry, gene expression analysis, Western blotting, measurement of glutamate and total antioxidant concentrations were recruited. (3) Results: HepG2, Caco-2, and MCF-7 were the most sensitive cell lines; HepG2 (ATRA; 36.2, EC19; 42.2 and EC23; 0.74 µM), Caco-2 (ATRA; 58.0, EC19; 10.8 and EC23; 14.7 µM) and MCF-7 (ATRA; 99.0, EC19; 9.4 and EC23; 5.56 µM). Caco-2 cells were selected for further biochemical investigations. Isobologram analysis revealed the combined synergistic effects with 5-fluorouracil with substantial reduction in IC50. All retinoids induced apoptosis but EC19 had higher potency, with significant cell cycle arrest at subG0-G1, -S and G2/M phases, than ATRA and EC23. Moreover, EC19 reduced cellular metastasis in a transwell invasion assay due to overexpression of E-cadherin, retinoic acid-induced 2 (RAI2) and Werner (WRN) genes. (4) Conclusion: The present study suggests that EC-synthetic retinoids, particularly EC19, can be effective, alone or in combinations, for potential anticancer activity to colorectal cancer. Further in vivo studies are recommended to pave the way for clinical applications.

SMAD4 mutations and cross-talk between TGF-β/IFNγ signaling accelerate rates of DNA damage and cellular senescence, resulting in a segmental progeroid syndrome-the Myhre syndrome.

SMAD4 encodes a member of the SMAD family of proteins involved in the TGF-β signaling pathway. Potentially heritable, autosomal dominant, gain-of-function heterozygous variants of SMAD4 cause a rare developmental disorder, the Myhre syndrome, which is associated with a wide range of developmental and post-developmental phenotypes that we now characterize as a novel segmental progeroid syndrome. Whole-exome sequencing of a patient referred to our International Registry of Werner Syndrome revealed a heterozygous p.Arg496Cys variant of the SMAD4 gene. To investigate the role of SMAD4 mutations in accelerated senescence, we generated cellular models overexpressing either wild-type SMAD4 or mutant SMAD4-R496C in normal skin fibroblasts. We found that cells expressing the SMAD4-R496C mutant exhibited decreased proliferation and elevated expression of cellular senescence and inflammatory markers, including IL-6, IFNγ, and a TGF-β target gene, PAI-1. Here we show that transient exposure to TGF-β, an inflammatory cytokine, followed by chronic IFNγ stimulation, accelerated rates of senescence that were associated with increased DNA damage foci and SMAD4 expression. TGF-β, IFNγ, or combinations of both were not sufficient to reduce proliferation rates of fibroblasts. In contrast, TGF-β alone was able to induce preadipocyte senescence via induction of the mTOR protein. The mTOR inhibitor rapamycin mitigated TGF-β-induced expression of p21, p16, and DNA damage foci and improved replicative potential of preadipocytes, supporting the cell-specific response to this cytokine. These findings collectively suggest that persistent DNA damage and cross-talk between TGF-β/IFNγ pathways contribute to a series of molecular events leading to cellular senescence and a segmental progeroid syndrome.

Decreased thickness of peripapillary retinal nerve fiber layer and ganglion cell complex in patients with Werner's syndrome

AbstractPurposeWerner's syndrome is a rare autosomal recessive disorder that is characterized by a premature aged‐appearance, for example, grey hair, scleroderma‐like skin in young adults. It typically starts in the 20–30s followed by age‐related disorders such as juvenile cataracts, diabetes mellitus, atherosclerosis, cancers, and osteoporosis. The purpose of this study was to assess the alterations of the peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell complex (GCC) in patients with Werner syndrome. The retinal images obtained by spectral‐domain optical coherence tomography (SD‐OCT) from eight patients with Werner's syndrome were compared to those of 10 age‐matched healthy controls.MethodsSixteen eyes of eight patients with Werner's syndrome consisting of four men and four women were studied. The 16 eyes of the Werner's patients were compared to 20 eyes of 10 volunteers (five men and five women) who had no high myopia, glaucoma, or other macular disorders as healthy controls. There was no significant difference in the ages (p > 0.05) and the axial length (WS, 23.91 ± 0.85 mm; Control, 23.7 ± 1.04 mm; p > 0.05) between the two groups. We quantified the mean thickness of the pRNFL and the GCC from the OCT images for both groups. The significance of the differences in the findings was determined with the Mann–Whitney U‐test. Statistical significance was defined as p < 0.05.ResultsThe mean pRNFL thickness in the Werner's group was 88.1 ± 16.9 μm which was significantly thinner that of the control group at 109.8 ± 13.0 μm (p < 0.05). The mean GCC thickness was 80.8 ± 10.3 μm in the Werner's group which was also significantly thinner than that of the control group at 95.4 ± 5.65 μm (p < 0.05).ConclusionsThe significantly thinner pRNFL and GCC in the Werner's group than the control group indicates that ophthalmologists should consider Werner's syndrome in their differential diagnosis when a similar finding is made in a young individual.

Werner Syndrome

A 36-year-old male presented with young-onset diabetes and advanced peripheral vascular disease. He had a history of bilateral juvenile cataracts and premature aged appearance. Closer scrutiny unraveled multiple endocrine and nonendocrine abnormalities. Genetic studies revealed a novel pathogenic variant (homozygous c.3233+2T>c) confirming and expanding the mutation spectrum of Werner syndrome. This report highlights the need for precise diagnosis, which has important implications for prognosis and genetic counseling.

Two Cases of Intractable Foot Ulcer in Patients with Werner Syndrome Successfully Treated with Local Negative Pressure Wound Therapy and Extracellular Matrix Graft

Two Cases of Intractable Foot Ulcer in Patients with Werner Syndrome Successfully Treated with Local Negative Pressure Wound Therapy and Extracellular Matrix Graft

Slowing cellular senescence

Aging Whereas cellular senescence is known to promote aging, many of the mechanisms controlling this process remain poorly understood. Using human mesenchymal precursor cells (hMPCs) carrying pathogenic mutations of the premature aging diseases Werner syndrome and Hutchinson-Gilford progeria syndrome, Wang et al. conducted a genome-wide CRISPR-Cas9–based screen to identify genes that could affect cellular senescence. They identified KAT7 , a histone acetyltransferase gene, as a driver of senescence in hMPCs. Inactivation of Kat7 in mice aging normally and in prematurely aging progeroid mice extended their life span. Although KAT7 requires further study in other cell types, these experiments highlight the value of genome-wide CRISPR-Cas9 screens and further illuminate the mechanisms controlling senescence. Sci. Transl. Med. 13 , eabd2655 (2020).

Time gap between the onset and diagnosis in Werner syndrome: a nationwide survey and the 2020 registry in Japan.

Patients with Werner syndrome present with diverse signs of aging that begin in adolescence. A Japanese nationwide survey was conducted to establish a registry that could clarify the disease profile of patients with Werner syndrome. The questionnaires were sent to 7888 doctors. The survey identified 116 patients diagnosed with Werner syndrome based on the diagnosis criteria. Forty patients were enrolled in the registry. Data on clinical symptoms, treatment information, and laboratory examination from patients who provided informed consent were collected. The data at enrollment were analyzed. The patients’ average age at enrollment was 50.1±7.5 years. The mean onset age was 26.1±9.5 years, but the mean age at diagnosis was 42.5±8.6 years. Average height and weight of the study patients were lower than those of Japanese individuals. Almost all patients experienced hair change and cataracts. More than 60% of patients presented with glycolipid abnormalities. Overall, 15% of patients had a history of foot amputation. Approximately 30% of the patients’ parents had a consanguineous marriage. The average grip strength, walking speed, and skeletal muscle mass index met the diagnostic criteria for sarcopenia. The registry revealed that there are opportunities for early diagnosis and intervention; therefore, sensitization about the disease is needed.

Management guideline for Werner syndrome 2020 8. Calcification in tendons associated with Werner syndrome.

To clarify the diagnostic value of the calcification in the Achilles tendon for Werner syndrome. Calcification of the Achilles tendon in the plain radiograph was investigated in 92 patients with Werner syndrome provided from the nationwide secondary survey in 2010. And the same investigation was performed for 2151 feet in 1853 patients without Werner syndrome, who underwent foot and ankle surgeries at the department of orthopaedic surgery in Nara Medical University from 2004 to 2015. Achilles tendon calcification was observed in 70 (76.1%) out of 92 patients with Werner syndrome, whereas that was observed only in 19 feet (0.88%) without Werner syndrome, accompanied by 1 to 4 calcified masses with a maximum diameter ranging from 9.7mm to 63.2mm. The frequency of Achilles tendon calcification in patients with Werner syndrome is far higher than that of patients without Werner syndrome. Achilles tendon calcification could be included in the diagnostic criteria for Werner syndrome. Geriatr Gerontol Int 2021; 21: 163-165.

Management guideline for Werner syndrome 2020 1. Dyslipidemia and fatty liver associated with Werner syndrome.

For the purpose of examining the characteristics of dyslipidemia and fatty liver in patients with Werner syndrome in Japan in recent years, we searched all case reports of Japanese Werner syndrome reported on Medical Online and PubMed since 1996, and collected and examined the data and clinical features described in these reports. In addition, as there are few descriptions of treatment methods in these reports from Medical Online and PubMed, we analyzed 12 cases for which detailed data on treatment methods are available at Chiba University. Geriatr Gerontol Int 2021; 21: 133-138.

Management guideline for Werner syndrome 2020. 6. Skin ulcers associated with Werner syndrome: Prevention and non-surgical and surgical treatment.

To provide guidelines on the diagnosis, treatment, and prevention of skin ulcers in Werner syndrome. This article was based on literature from 1996, when WRN was identified as a gene responsible for Werner syndrome, and we evaluated several authentic clinical cases of genetically diagnosed patients. There were 63 patients with Werner syndrome in the Japanese reports retrieved from Medical Online between January 1996 and December 2017. There were 56 patients with Werner syndrome in English reports written by Japanese authors and retrieved from PubMed during the same period. Records on skin ulcers were found in 27 (43%) out of 63 patients and 22 (40%) out of 56 patients from the Japanese and English reports, respectively. The reported ulcers were often located at the distal one-third of the lower legs. There were 8 patients with callosities in the foot in the Japanese reports and 9 patients in the English reports. A skin ulcer in Werner syndrome is generally intractable. Weight-bearing ulcers or callosity should be critically assessed in surgical procedures because they have effects on patient pain and gait. By adopting a recently advanced technique to facilitate wound healing, the cases of ulcers that were difficult to treat and those requiring major operations can be closed with minimally invasive surgery. Skin ulcers in Werner syndrome are refractory, and they lead to reduced quality of life of patients. A callosity in Werner syndrome is an important therapeutic target for the prevention of ulcers. Geriatr Gerontol Int 2021; 21: 153-159.

The Impact of Vitamin C on Different System Models of Werner Syndrome

Significance: Werner syndrome (WS) is a rare autosomal recessive malady typified by a pro-oxidant/proinflammatory status, genetic instability, and by the early onset of numerous age-associated illnesses. The protein malfunctioning in WS individuals (WRN) is a helicase/exonuclease implicated in transcription, DNA replication/repair, and telomere maintenance. Recent Advances: In the last two decades, a series of important biological systems were created to comprehend at the molecular level the effect of a defective WRN protein. Such biological tools include mouse and worm (Caenorhabditis elegans) with a mutation in the Wrn helicase ortholog as well as human WS-induced pluripotent stem cells that can ultimately be differentiated into most cell lineages. Such WS models have identified anomalies related to the hallmarks of aging. Most importantly, vitamin C counteracts these age-related cellular phenotypes in these systems. Critical Issues: Vitamin C is the only antioxidant agent capable of reversing the cellular aging-related phenotypes in those biological systems. Since vitamin C is a cofactor for many hydroxylases and mono- or dioxygenase, it adds another level of complexity in deciphering the exact molecular pathways affected by this vitamin. Moreover, it is still unclear whether a short- or long-term vitamin C supplementation in human WS patients who already display aging-related phenotypes will have a beneficial impact. Future Directions: The discovery of new molecular markers specific to the modified biological pathways in WS that can be used for novel imaging techniques or as blood markers will be necessary to assess the favorable effect of vitamin C supplementation in WS. Antioxid. Redox Signal. 34, 856-874.

Management guideline for Werner syndrome 2020. 2. Sarcopenia associated with Werner syndrome.

Sarcopenia is defined as a condition that combines decreased skeletal muscle mass with weakness or decreased physical function. It is well known that in older adults, the presence of sarcopenia is a risk of frailty, falls and physical dysfunction. Patients with Werner syndrome are characterized by visceral fat accumulation and thin limbs, but the prevalence of sarcopenia in patients with Werner syndrome has not been investigated. A literature search was conducted using Werner syndrome and skeletal muscle as keywords. We also analyzed data from our 7 Werner syndrome patients. A literature search on the relationship between Werner syndrome and skeletal muscle yielded only one article reported from Japan. According to this paper, a decrease in skeletal muscle mass (appendicular skeletal muscle index) was observed in all 9 Werner syndromes investigated. On the other hand, in our 7 Werner syndrome patients, their appendicular skeletal muscle indexes were below the standard value except for one male patient who had continued resistance exercise. The decrease in skeletal muscle mass frequently occurs in patients with Werner syndrome. However, resistance exercise may prevent the appearance of sarcopenia and requires early intervention in patients with Werner syndrome. Geriatr Gerontol Int 2021; 21: 139-141.

Management guideline for Werner syndrome 2020. 3. Diabetes associated with Werner syndrome.

To evaluate the characteristics of diabetes associated with Werner syndrome. A literature search was done with search term "Werner syndrome" and "Diabetes". Prevalence of diabetes is extremely high in Werner syndrome. Diabetes associated with Werner syndrome is classified as "accompanied with other diseases and conditions and the one occurring mainly in association with other genetic syndromes." This type of diabetes is marked by accumulated visceral fat and high insulin resistance, despite low body mass index. Thiazolidine derivatives and metformin are effective for glycemic control. New antidiabetic drugs, such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists, could be potentially beneficial for patients with Werner syndrome. Furthermore, the establishment of diet therapy as well as exercise therapy is warranted. Geriatr Gerontol Int 2021; 21: 142-145.

Management guideline for Werner syndrome 2020. 4. Osteoporosis associated with Werner syndrome.

Management guideline for Werner syndrome 2020. 4. Osteoporosis associated with Werner syndrome.

Management guideline for Werner syndrome 2020. 7. Skin ulcer associated with Werner syndrome: Dermatological treatment.

Skin ulcers in Werner's syndrome often arise from hyperkeratotic lesions and trauma to pressure points such as the plantar region, and are more difficult to treat than wound healing in healthy individuals. Multiple factors contribute to the intractable skin ulcers in Werner's syndrome, including skin thinning, sclerosis, fatty tissue loss, impaired blood flow, calcification, and excessive pressure due to osteoarticular deformity. Treatment includes topical application of a keratolytic agent for keratosis around the ulcer. Treatment of ulcers is the same as for normal ulcers, and if the ulcer is associated with infection and necrotic tissue, surgical debridement with a scalpel or scissors should be performed as much as possible after washing with saline or mildly warm water or with an antibacterial agent. Topical medications that promote softening and debridement of the necrotic tissue are used with careful control of moisture in the wound. Topical agents that promote granulation should be used in wounds where necrotic tissue has been removed without infection. Dressings to maintain a moist environment in the wound may also be useful. If the wound does not improve with conservative treatment, surgical treatment should be considered. Geriatr Gerontol Int 2021; 21: 160-162.