Metabolomic analysis of dietary-restriction-induced attenuation of sarcopenia in prematurely aging DNA repair-deficient mice

BACKGROUND

Sarcopenia is characterized by loss of skeletal muscle mass and function, and is a major risk factor for disability and independence in the elderly. Effective medication is not available. Dietary restriction (DR) has been found to attenuate aging and aging-related diseases, including sarcopenia, but the mechanism of both DR and sarcopenia are incompletely understood.

METHODS

In this study, mice body weight, fore and all limb grip strength, and motor learning and coordination performance were first analysed to evaluate the DR effects on muscle functioning. Liquid chromatography-mass spectrometry (LC-MS) was utilized for the metabolomics study of the DR effects on sarcopenia in progeroid DNA repair-deficient Ercc1∆/- and Xpg-/- mice, to identify potential biomarkers for attenuation of sarcopenia.

RESULTS

Muscle mass was significantly (P < 0.05) decreased (13-20%) by DR; however, the muscle quality was improved with retained fore limbs and all limbs grip strength in Ercc1∆/- and Xpg-/- mice. The LC-MS results revealed that metabolites and pathways related to oxidative-stress, that is, GSSG/GSH (P < 0.01); inflammation, that is, 9-HODE, 11-HETE (P < 0.05), PGE2, PGD2, and TXB2 (P < 0.01); and muscle growth (PGF2α) (P < 0.01) and regeneration stimulation (PGE2) (P < 0.05) are significantly downregulated by DR. On the other hand, anti-inflammatory indicator and several related metabolites, that is, β-hydroxybutyrate (P < 0.01), 14,15-DiHETE (P < 0.0001), 8,9-EET, 12,13-DiHODE, and PGF1 (P < 0.05); consumption of sources of energy (i.e., muscle and liver glycogen); and energy production pathways, that is, glycolysis (glucose, glucose-6-P, fructose-6-P) (P < 0.01), tricarboxylic acid cycle (succinyl-CoA, malate) (P < 0.001), and gluconeogenesis-related metabolite, alanine (P < 0.01), are significantly upregulated by DR. The notably (P < 0.01) down-modulated muscle growth (PGF2α) and regeneration (PGE2) stimulation metabolite and the increased consumption of glycogen in muscle and liver may be related to the significantly (P < 0.01) lower body weight and muscle mass by DR. The downregulated oxidative stress, pro-inflammatory mediators, and upregulated anti-inflammatory metabolites resulted in a lower energy expenditure, which contributed to enhanced muscle quality together with upregulated energy production pathways by DR. The improved muscle quality may explain why grip strength is maintained and motor coordination and learning performance are improved by DR in Ercc1∆/- and Xpg-/- mice.

CONCLUSIONS

This study provides fundamental supporting information on biomarkers and pathways related to the attenuation of sarcopenia, which might facilitate its diagnosis, prevention, and clinical therapy.

Senescence, regulators of alternative splicing and effects of trametinib treatment in progeroid syndromes

Progeroid syndromes such as Hutchinson Gilford Progeroid syndrome (HGPS), Werner syndrome (WS) and Cockayne syndrome (CS), result in severely reduced lifespans and premature ageing. Normal senescent cells show splicing factor dysregulation, which has not yet been investigated in syndromic senescent cells. We sought to investigate the senescence characteristics and splicing factor expression profiles of progeroid dermal fibroblasts. Natural cellular senescence can be reversed by application of the senomorphic drug, trametinib, so we also investigated its ability to reverse senescence characteristics in syndromic cells. We found that progeroid cultures had a higher senescence burden, but did not always have differences in levels of proliferation, DNA damage repair and apoptosis. Splicing factor gene expression appeared dysregulated across the three syndromes. 10 µM trametinib reduced senescent cell load and affected other aspects of the senescence phenotype (including splicing factor expression) in HGPS and Cockayne syndromes. Werner syndrome cells did not demonstrate changes in in senescence following treatment. Splicing factor dysregulation in progeroid cells provides further evidence to support this mechanism as a hallmark of cellular ageing and highlights the use of progeroid syndrome cells in the research of ageing and age-related disease. This study suggests that senomorphic drugs such as trametinib could be a useful adjunct to therapy for progeroid diseases.

Sex-specific preservation of neuromuscular function and metabolism following systemic transplantation of multipotent adult stem cells in a murine model of progeria

Onset and rates of sarcopenia, a disease characterized by a loss of muscle mass and function with age, vary greatly between sexes. Currently, no clinical interventions successfully arrest age-related muscle impairments since the decline is frequently multifactorial. Previously, we found that systemic transplantation of our unique adult multipotent muscle-derived stem/progenitor cells (MDSPCs) isolated from young mice-but not old-extends the health-span in DNA damage mouse models of progeria, a disease of accelerated aging. Additionally, induced neovascularization in the muscles and brain-where no transplanted cells were detected-strongly suggests a systemic therapeutic mechanism, possibly activated through circulating secreted factors. Herein, we used ZMPSTE24-deficient mice, a lamin A defect progeria model, to investigate the ability of young MDSPCs to preserve neuromuscular tissue structure and function. We show that progeroid ZMPST24-deficient mice faithfully exhibit sarcopenia and age-related metabolic dysfunction. However, systemic transplantation of young MDSPCs into ZMPSTE24-deficient progeroid mice sustained healthy function and histopathology of muscular tissues throughout their 6-month life span in a sex-specific manner. Indeed, female-but not male-mice systemically transplanted with young MDSPCs demonstrated significant preservation of muscle endurance, muscle fiber size, mitochondrial respirometry, and neuromuscular junction morphometrics. These novel findings strongly suggest that young MDSPCs modulate the systemic environment of aged animals by secreted rejuvenating factors to maintain a healthy homeostasis in a sex-specific manner and that the female muscle microenvironment remains responsive to exogenous regenerative cues in older age. This work highlights the age- and sex-related differences in neuromuscular tissue degeneration and the future prospect of preserving health in older adults with systemic regenerative treatments.

A new fluorescent probe for the visualization of progerin

Hutchinson-Gilford progeria syndrome (HGPS) or progeria is a rare genetic disease that causes premature aging, leading to a drastic reduction in the life expectancy of patients. Progeria is mainly caused by the intracellular accumulation of a defective protein called progerin, generated from a mutation in the LMNA gene. Currently, there is only one approved drug for the treatment of progeria, which has limited efficacy. It is believed that progerin levels are the most important biomarker related to the severity of the disease. However, there is a lack of effective tools to directly visualize progerin in the native cellular models, since the commercially available antibodies are not well suited for the direct visualization of progerin in cells from the mouse model of the disease. In this context, an alternative option for the visualization of a protein relies on the use of fluorescent chemical probes, molecules with affinity and specificity towards a protein. In this work we report the synthesis and characterization of a new fluorescent probe (UCM-23079) that allows for the direct visualization of progerin in cells from the most widely used progeroid mouse model. Thus, UCM-23079 is a new tool compound that could help prioritize potential preclinical therapies towards the final goal of finding a definitive cure for progeria.

Purkinje-cell-specific DNA repair-deficient mice reveal that dietary restriction protects neurons by cell-intrinsic preservation of genomic health

Dietary restriction (DR) is a universal anti-aging intervention, which reduces age-related nervous system pathologies and neurological decline. The degree to which the neuroprotective effect of DR operates by attenuating cell intrinsic degradative processes rather than influencing non-cell autonomous factors such as glial and vascular health or systemic inflammatory status is incompletely understood. Following up on our finding that DR has a remarkably large beneficial effect on nervous system pathology in whole-body DNA repair-deficient progeroid mice, we show here that DR also exerts strong neuroprotection in mouse models in which a single neuronal cell type, i.e., cerebellar Purkinje cells, experience genotoxic stress and consequent premature aging-like dysfunction. Purkinje cell specific hypomorphic and knock-out ERCC1 mice on DR retained 40 and 25% more neurons, respectively, with equal protection against P53 activation, and alike results from whole-body ERCC1-deficient mice. Our findings show that DR strongly reduces Purkinje cell death in our Purkinje cell-specific accelerated aging mouse model, indicating that DR protects Purkinje cells from intrinsic DNA-damage-driven neurodegeneration.

The Nuclear Envelope in Ageing and Progeria

Development from embryo to adult, organismal homeostasis and ageing are consecutive processes that rely on several functions of the nuclear envelope (NE). The NE compartmentalises the eukaryotic cells and provides physical stability to the genetic material in the nucleus. It provides spatiotemporal regulation of gene expression by controlling nuclear import and hence access of transcription factors to target genes as well as organisation of the genome into open and closed compartments. In addition, positioning of chromatin relative to the NE is important for DNA replication and repair and thereby also for genome stability. We discuss here the relevance of the NE in two classes of age-related human diseases. Firstly, we focus on the progeria syndromes Hutchinson-Gilford (HGPS) and Nestor-Guillermo (NGPS), which are caused by mutations in the LMNA and BANF1 genes, respectively. Both genes encode ubiquitously expressed components of the nuclear lamina that underlines the nuclear membranes. HGPS and NGPS patients manifest symptoms of accelerated ageing and cells from affected individuals show similar defects as cells from healthy old donors, including signs of increased DNA damage and epigenetic alternations. Secondly, we describe how several age-related neurodegenerative diseases, such as amyotrophic lateral sclerosis and Huntington's disease, are related with defects in nucleocytoplasmic transport. A common feature of this class of diseases is the accumulation of nuclear pore proteins and other transport factors in inclusions. Importantly, genetic manipulations of the nucleocytoplasmic transport machinery can alleviate disease-related phenotypes in cell and animal models, paving the way for potential therapeutic interventions.

Vascular smooth muscle cell aging: Insights from Hutchinson-Gilford progeria syndrome

Vascular smooth muscle cells (VSMCs) constitute the principal cellular component of the medial layer of arteries and are responsible for vessel contraction and relaxation in response to blood flow. Alterations in VSMCs can hinder vascular system function, leading to vascular stiffness, calcification and atherosclerosis, which in turn may result in life-threatening complications. Pathological changes in VSMCs typically correlate with chronological age; however, there are certain conditions and diseases, such as Hutchinson-Gilford progeria syndrome (HGPS), that can accelerate this process, resulting in premature vascular aging. HGPS is a rare genetic disorder characterized by severe VSMC loss, accelerated atherosclerosis and death from myocardial infarction or stroke during the adolescence. Because experiments with mouse models have demonstrated that alterations in VSMCs are responsible for early atherosclerosis in HGPS, studies on this disease can provide insights into the mechanisms of vascular aging and assess the relative contribution of VSMCs to this process.

Neuropathology of classic myotonic dystrophy type 1 is characterized by both early initiation of primary age-related tauopathy of the hippocampus and unique 3-repeat tauopathy of the brainstem

Myotonic dystrophy type 1 (DM1) is an inherited autosomal-dominant condition that induces altered splicing of transcripts, including MAPT, leading to a distinctive abnormal deposition of tau protein in the CNS. We characterized the tau isoforms of abnormal depositions in the brains of 4 patients with classic DM1 by immunohistochemistry using isoform-specific antibodies. All patients, including those of presenile age, showed numerous neurofibrillary tangles (NFTs) of both 3-repeat and 4-repeat tau in the limbic area and mild involvement in the cerebral cortex. Amyloid-β deposition was only seen in 1 senile case while cortical tauopathy in all other cases was consistent with primary age-related tauopathy (PART). In the putamen and globus pallidus, only a few tau deposits were observed. Tau deposits in the brainstem frequently showed a DM1-specific pattern with 3-repeat tau dominant NFTs. Additionally, tau-positive astrocytes morphologically similar to tufted astrocytes and astrocytic plaques were occasionally observed in the brainstem; however, they were predominantly composed of 3-repeat tau. Thus, the classic DM1 showed both early onset of PART-like pathology in the limbic areas as a progeroid syndrome of DM1 and an abnormal splicing event in the brainstem leading to 3-repeat tau dominant accumulation with both neuronal and astrocytic involvement.

Progerin induces a phenotypic switch in vascular smooth muscle cells and triggers replication stress and an aging-associated secretory signature

Hutchinson-Gilford progeria syndrome is a premature aging disease caused by LMNA gene mutation and the production of a truncated prelamin A protein "progerin" that elicits cellular and organismal toxicity. Progerin accumulates in the vasculature, being especially detrimental for vascular smooth muscle cells (VSMC). Vessel stiffening and aortic atherosclerosis in HGPS patients are accompanied by VSMC depletion in the medial layer, altered extracellular matrix (ECM), and thickening of the adventitial layer. Mechanisms whereby progerin causes massive VSMC loss and vessel alterations remain poorly understood. Mature VSMC retain phenotypic plasticity and can switch to a synthetic/proliferative phenotype. Here, we show that progerin expression in human and mouse VSMC causes a switch towards the synthetic phenotype. This switch elicits some level of replication stress in normal cells, which is exacerbated in the presence of progerin, leading to telomere fragility, genomic instability, and ultimately VSMC death. Calcitriol prevents replication stress, telomere fragility, and genomic instability, reducing VSMC death. In addition, RNA-seq analysis shows induction of a profibrotic and pro-inflammatory aging-associated secretory phenotype upon progerin expression in human primary VSMC. Our data suggest that phenotypic switch-induced replication stress might be an underlying cause of VSMC loss in progeria, which together with loss of contractile features and gain of profibrotic and pro-inflammatory signatures contribute to vascular stiffness in HGPS.

Lipodystrophy-associated progeroid syndromes

With the exception of HIV-associated lipodystrophy, lipodystrophy syndromes are rare conditions characterized by a lack of adipose tissue, which is not generally recovered. As a consequence, an ectopic deposition of lipids frequently occurs, which usually leads to insulin resistance, atherogenic dyslipidemia, and hepatic steatosis. These disorders include certain accelerated aging syndromes or progeroid syndromes. Even though each of them has unique clinical features, most show common clinical characteristics that affect growth, skin and appendages, adipose tissue, muscle, and bone and, in some of them, life expectancy is reduced. Although the molecular bases of these Mendelian disorders are very diverse and not well known, genomic instability is frequent as a consequence of impairment of nuclear organization, chromatin structure, and DNA repair, as well as epigenetic dysregulation and mitochondrial dysfunction. In this review, the main clinical features of the lipodystrophy-associated progeroid syndromes will be described along with their causes and pathogenic mechanisms, and an attempt will be made to identify which of López-Otín's hallmarks of aging are present.

Reduction of senescent fibro-adipogenic progenitors in progeria-aged muscle by senolytics rescues the function of muscle stem cells

BACKGROUND

Fibro-adipogenic progenitors (FAPs) in the muscles have been found to interact closely with muscle progenitor/stem cells (MPCs) and facilitate muscle regeneration at normal conditions. However, it is not clear how FAPs may interact with MPCs in aged muscles. Senolytics have been demonstrated to selectively eliminate senescent cells and generate therapeutic benefits on ageing and multiple age-related disease models.

METHODS

By studying the muscles and primary cells of age matched WT mice and Zmpste24^-/- (Z24^-/- ) mice, an accelerated ageing model for Hutchinson-Gilford progeria syndrome (HGPS), we examined the interaction between FAPs and MPCs in progeria-aged muscle, and the potential effect of senolytic drug fisetin in removing senescent FAPs and improving the function of MPCs.

RESULTS

We observed that, compared with muscles of WT mice, muscles of Z24^-/- mice contained a significantly increased number of FAPs (2.4-fold; n > =6, P < 0.05) and decreased number of MPCs (2.8-fold; n > =6, P < 0.05). FAPs isolated from Z24^-/- muscle contained about 44% SA-β-gal+ senescent cells, in contrast to about 3.5% senescent cells in FAPs isolated from WT muscle (n > =6, P < 0.001). The co-culture of Z24^-/- FAPs with WT MPCs resulted in impaired proliferation and myogenesis potential of WT MPCs, with the number of BrdU positive proliferative cells being reduced for 3.3 times (n > =6, P < 0.001) and the number of myosin heavy chain (MHC)-positive myotubes being reduced for 4.5 times (n > =6, P < 0.001). The treatment of the in vitro co-culture system of Z24^-/- FAPs and WT MPCs with the senolytic drug fisetin led to increased apoptosis of Z24^-/- FAPs (14.5-fold; n > =6, P < 0.001) and rescued the impaired function of MPCs by increasing the number of MHC-positive myotubes for 3.1 times (n > =6, P < 0.001). Treatment of Z24^-/- mice with fisetin in vivo was effective in reducing the number of senescent FAPs (2.2-fold, n > =6, P < 0.05) and restoring the number of muscle stem cells (2.6-fold, n > =6, P < 0.05), leading to improved muscle pathology in Z24^-/- mice.

CONCLUSIONS

These results indicate that the application of senolytics in the progeria-aged muscles can be an efficient strategy to remove senescent cells, including senescent FAPs, which results in improved function of muscle progenitor/stem cells. The senescent FAPs can be a potential novel target for therapeutic treatment of progeria ageing related muscle diseases.

Detection of Cerebrovascular Disease in a Child with Hutchinson-Gilford Progeria Syndrome Using MR Angiography: A Case Report

Hutchinson-Gilford progeria syndrome (HGPS) is a rare, progressive, premature aging syndrome with early morbidity due to cardiovascular and cerebrovascular diseases. Clinical symptoms are very diverse, including non-specific symptoms such as growth retardation, scleroderma, alopecia, and osteoporosis, as well as hypertension and cardiovascular diseases that occur in childhood and adolescence due to accelerated vascular aging. In patients with HGPS, MR angiography is recommended for early diagnosis of asymptomatic stroke or vascular changes and to assess increased risk of cerebrovascular disease. We report the second domestic case of HGPS confirmed by genetic analysis in a 5-year-old child with typical clinical features, and the first English case report in Korea to present brain MR angiography findings.

Vascular senescence in progeria: role of endothelial dysfunction

Aims

Hutchinson-Gilford progeria syndrome (HGPS) is a pre-mature aging disorder caused by the mutation of the LMNA gene leading to an irreversibly farnesylated lamin A protein: progerin. The major causes of death in HGPS are coronary and arterial occlusive disease. In the murine model of HGPS, vascular smooth muscle cell (VSMC) loss is the primary vascular manifestation, which is different from the arterial occlusive disease seen in older patients.

Methods and results

To identify the mechanisms of HGPS vascular disease in humans, we differentiated isogenic endothelial cells (ECs) and VSMCs from HGPS-induced pluripotent stem cells (iPSCs) and control-iPSCs. Both HGPS-ECs and HGPS-VSMCs manifested cellular hallmarks of aging, including dysmorphic nuclei, impaired proliferation, increased β-galactosidase staining, shortened telomeres, up-regulated secretion of inflammatory cytokines, increased DNA damage, loss of heterochromatin, and altered shelterin protein complex (SPC) expression. However, at similar days after differentiation, even with lower levels of progerin, HGPS-ECs manifested more severe signs of senescence, as indicated in part by a higher percentage of β-galactosidase positive cells, shorter telomere length, and more DNA damage signals. We observed increased γH2A.X binding to RAP1 and reduced TRF2 binding to lamin A in HGPS-ECs but not in HGPS-VSMCs. The expression of γH2A.X was greater in HGPS-ECs than in HGPS-VSMCs and is associated with greater telomere shortening, impaired SPC interactions, and loss of heterochromatin.

Conclusion

Although progerin expression has a deleterious effect on both ECs and VSMCs, the dysfunction is greater in HGPS-ECs compared with HGPS-VSMCs. This study suggests that an endothelial-targeted therapy may be useful for HGPS patients.

Whole-exome sequencing reveals POLR3B variants associated with progeria-related Wiedemann-Rautenstrauch syndrome

Background

Wiedemann-Rautenstrauch syndrome (WRS) is a rare autosomal recessive neonatal progeroid disorder characterized by prenatal and postnatal growth retardation, short stature, a progeroid appearance, hypotonia, and mental impairment.

Case presentation

A 6-year-old patient, who initially presented with multiple postnatal abnormalities, facial dysplasia, micrognathia, skull appearance, hallux valgus, and congenital dislocation of the hip, was recruited in this study. The patient was initially diagnosed with progeria. The mother of the patient had abnormal fetal development during her second pregnancy check-up, and the clinical phenotype of the fetus was similar to that of the patient. Whole-exome sequencing (WES) of the patient was performed, and POLR3B compound heterozygous variants—c.2191G > C:p.E731Q and c.3046G > A:p.V1016M—were identified in the patient. Using Sanger sequencing, we found that the phenotypes and genotypes were segregated within the pedigree. These two variants are novel and not found in the gnomAD and 1000 Genomes databases. The two mutation sites are highly conserved between humans and zebrafish.

Conclusions

Our study not only identified a novel WRS-associated gene, POLR3B, but also broadened the mutational and phenotypic spectra of POLR3B. Furthermore, WES may be useful for identifying rare disease-related genetic variants.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-021-01112-6.

Hutchinson-Gilford Progeria Syndrome: An Overview of the Molecular Mechanism, Pathophysiology and Therapeutic Approach

Lamin A/C encoded by the LMNA gene is an essential component for maintaining the nuclear structure. Mutation in the lamin A/C leads to a group of inherited disorders is known as laminopathies. In the human body, there are several mutations in the LMNA gene that have been identified. It can affect diverse organs or tissues or can be systemic, causing different diseases. In this review, we mainly focused on one of the most severe laminopathies, Hutchinson-Gilford progeria syndrome (HGPS). HGPS is an immensely uncommon, deadly, metameric ill-timed laminopathies caused by the abnormal splicing of the LMNA gene and production of an aberrant protein known as progerin. Here, we also presented the currently available data on the molecular mechanism, pathophysiology, available treatment, and future approaches to this deadly disease. Due to the production of progerin, an abnormal protein leads to an abnormality in nuclear structure, defects in DNA repair, shortening of telomere, and impairment in gene regulation which ultimately results in aging in the early stage of life. Now some treatment options are available for this disease, but a proper understanding of the molecular mechanism of this disease will help to develop a more appropriate treatment which makes it an emerging area of research.

Systemic transplantation of adult multipotent stem cells prevents articular cartilage degeneration in a mouse model of accelerated ageing

BACKGROUND

Osteoarthritis (OA) is one of the most prevalent joint diseases of advanced age and is a leading cause of disability worldwide. Ageing is a major risk factor for the articular cartilage (AC) degeneration that leads to OA, and the age-related decline in regenerative capacity accelerates OA progression. Here we demonstrate that systemic transplantation of a unique population of adult multipotent muscle-derived stem/progenitor cells (MDSPCs), isolated from young wild-type mice, into Zmpste24-/- mice (a model of Hutchinson-Gilford progeria syndrome, a condition marked by accelerated ageing), prevents ageing-related homeostatic decline of AC.

RESULTS

MDSPC treatment inhibited expression of cartilage-degrading factors such as pro-inflammatory cytokines and extracellular matrix-proteinases, whereas pro-regenerative markers associated with cartilage mechanical support and tensile strength, cartilage resilience, chondrocyte proliferation and differentiation, and cartilage growth, were increased. Notably, MDSPC transplantation also increased the expression level of genes known for their key roles in immunomodulation, autophagy, stress resistance, pro-longevity, and telomere protection. Our findings also indicate that MDSPC transplantation increased proteoglycan content by regulating chondrocyte proliferation.

CONCLUSIONS

Together, these findings demonstrate the ability of systemically transplanted young MDSPCs to preserve a healthy homeostasis and promote tissue regeneration at the molecular and tissue level in progeroid AC. These results highlight the therapeutic potential of systemically delivered multipotent adult stem cells to prevent age-associated AC degeneration.

Transcriptomic profiling of long- and short-lived mutant mice implicates mitochondrial metabolism in ageing and shows signatures of normal ageing in progeroid mice

Genetically modified mouse models of ageing are the living proof that lifespan and healthspan can be lengthened or shortened, and provide a powerful context in which to unravel the molecular mechanisms at work. In this study, we analysed and compared gene expression data from 10 long-lived and 8 short-lived mouse models of ageing. Transcriptome-wide correlation analysis revealed that mutations with equivalent effects on lifespan induce more similar transcriptomic changes, especially if they target the same pathway. Using functional enrichment analysis, we identified 58 gene sets with consistent changes in long- and short-lived mice, 55 of which were up-regulated in long-lived mice and down-regulated in short-lived mice. Half of these sets represented genes involved in energy and lipid metabolism, among which Ppargc1a, Mif, Aldh5a1 and Idh1 were frequently observed. Based on the gene sets with consistent changes, and also the whole transcriptome, the gene expression changes during normal ageing resembled the transcriptome of short-lived models, suggesting that accelerated ageing models reproduce partially the molecular changes of ageing. Finally, we identified new genetic interventions that may ameliorate ageing, by comparing the transcriptomes of 51 mouse mutants not previously associated with ageing to expression signatures of long- and short-lived mice and ageing-related changes.

Pathophysiology of premature aging characteristics in Mendelian progeroid disorders

Aging is a physiological process that is in part genetically determined. Some of the signs and symptoms of aging also occur prematurely in Mendelian disorders. Such disorders are excellent sources of information of underlying mechanisms for these components of aging, and studying these may allow detection of pathways that have not yet considered in detail in physiological aging. Here I define the clinical characteristics that constitute aging and propose that at least 40% of aging signs and symptoms should be present before an entity should be tagged as progeroid. A literature search using these characteristics yields 17 entities that fulfill this definition: Hutchinson-Gilford progeria, mandibulo-acral dysplasia, Nestor-Guillermo progeria, Werner syndrome, Cockayne syndrome, cutis laxa progeroid, Penttinen progeroid syndrome, Mandibular underdevelopment, Deafness, Progeroid features, Lipodystrophy, Fontaine progeroid syndrome, SHORT syndrome, Wiedemann-Rautenstrauch syndrome, Mulvihill-Smith syndrome, dyskeratosis congenita, Marfan syndrome lipodystrophy type, Warburg-Cinotti syndrome, Lessel syndrome and Bloom syndrome. The presenting and main characteristics of these entities are indicated briefly. Their pathophysiology is not complete pathophysiology is reviewed but only the pathophysiology of the premature aging characteristics of this series of entities is compared to the known mechanisms ("Hallmarks") of physiological aging as summarized in the review paper by Lopez-Otin and colleagues. Although many causative genes have not been studied fully for all known aging mechanisms the comparison demonstrates that additional mechanisms must play a role to explain the aging characteristic in some of the progeroid entities of the progeroid entities, and possibly also in physiological aging.

Hutchinson-Gilford progeria syndrome: Rejuvenating old drugs to fight accelerated ageing

What if the next generation of successful treatments was hidden in the current pharmacopoeia? Identifying new indications for existing drugs, also called the drug repurposing or drug rediscovery process, is a highly efficient and low-cost strategy. First reported almost a century ago, drug repurposing has emerged as a valuable therapeutic option for diseases that do not have specific treatments and rare diseases, in particular. This review focuses on Hutchinson-Gilford progeria syndrome (HGPS), a rare genetic disorder that induces accelerated and precocious aging, for which drug repurposing has led to the discovery of several potential treatments over the past decade.

[Anesthesia for a cesarean section on a pregnant patient with Cockayne syndrome: case report]

Cockayne syndrome is an autosomal recessive multi-systemic disorder due to DNA repair failure. It was originally described in 1936 in children of small stature, retinal atrophy and deafness, characterized by dwarfism, cachexia, photosensitivity, premature aging and neurologic deficits. The most typical feature is described as birdlike facies: protruding maxilla, facial lipoatrophy, sunken eyes, large ears and thin nose. Difficult airway management with subglottic stenosis and risk of gastric content aspiration has been described. Although the clinical characteristics of Cockayne syndrome have been well described in pediatric publications, there is only one report in the literature on anesthesia for an obstetric patient. We report the case of a pregnant patient diagnosed with Cockayne syndrome, submitted successfully to spinal anesthesia for a cesarean section due to cephalopelvic disproportion. In view of the difficult decision between inducing general anesthesia in a patient with a likely difficult airway, or neuraxial anesthesia in a patient with cardiovascular, respiratory and neurocognitive limitations, we suggest tailored management to reach the best results for the mother and newborn.

Drug repositioning for rare diseases: Knowledge-based success stories

While more than 7000 rare diseases have been identified, only about 5 percent benefit from a licensed treatment. As the majority of these diseases is life threatening, these facts underscore the need for new drugs. Drug repositioning is an alternative strategy in drug development, which represents an attractive opportunity for rare diseases. Drug repositioning (also called drug repurposing, drug reprofiling or drug re-tasking) consists in identifying for an already approved or investigational drug a new use outside the scope of the original medical indication. Drug repositioning is considered in the field of orphan drugs as being a faster and somehow less costly strategy than traditional new drug development for pharmaceutical companies. While several successful repositioning cases have been discovered by serendipity, most successes straightly derive from the molecular characterization of the concerned disease. This short commentary is mainly dedicated to these rationally-based success stories.

Diabetes mellitus coexisted with progeria: a case report of atypical Werner syndrome with novel LMNA mutations and literature review

Werner syndrome (WS) is a rare, adult-onset progeroid syndrome. Classic WS is caused by WRN mutation and partial atypical WS (AWS) is caused by LMNA mutation. A 19-year-old female patient with irregular menstruation and hyperglycemia was admitted. Physical examination revealed characteristic faces of progeria, graying and thinning of the hair scalp, thinner and atrophic skin over the hands and feet, as well as lipoatrophy of the extremities, undeveloped breasts at Tanner stage 3, and short stature. The patient also suffered from severe insulin-resistant diabetes mellitus, hyperlipidemia, fatty liver, and polycystic ovarian morphology. Possible WS was considered and both WRN and LMNA genes were analyzed. A novel missense mutation p.L140Q (c.419T>A) in the LMNA gene was identified and confirmed the diagnosis of AWS. Her father was a carrier of the same mutation. We carried out therapy for lowering blood glucose and lipid and improving insulin resistance, et al. The fasting glucose, postprandial glucose and triglyceride level was improved after treatment for 9 days. Literature review of AWS was performed to identify characteristics of the disease. Diabetes mellitus is one of the clinical manifestations of WS and attention must give to the differential diagnosis. Gene analysis is critical in the diagnosis of WS. According to the literature, classic and atypical WS differ in incidence, pathogenic gene, and clinical manifestations. Characteristic dermatological pathology may be significantly more important for the initial identification of AWS. Early detection, appropriate treatments, and regular follow-up may improve prognosis and survival of WS patients.

Premature aging syndromes: From patients to mechanism

Aging is an inevitable consequence of human life resulting in a gradual deterioration of cell, tissue and organismal function and an increased risk to develop chronic ailments. Premature aging syndromes, also known as progeroid syndromes, recapitulate many clinical features of normal aging and offer a unique opportunity to elucidate fundamental mechanisms that contribute to human aging. Progeroid syndromes can be broadly classified into those caused by perturbations of the nuclear lamina, a meshwork of proteins located underneath the inner nuclear membrane (laminopathies); and a second group that is caused by mutations that directly impair DNA replication and repair. We will focus mainly on laminopathies caused by incorrect processing of lamin A, an intermediate filament protein that resides at the nuclear periphery. Hutchinson-Gilford Progeria (HGPS) is an accelerated aging syndrome caused by a mutation in lamin A and one of the best studied laminopathies. HGPS patients exhibit clinical characteristics of premature aging, including alopecia, aberrant pigmentation, loss of subcutaneous fat and die in their teens as a result of atherosclerosis and cardiovascular complications. Here we summarize how cell- and mouse-based disease models provided mechanistic insights into human aging and discuss experimental strategies under consideration for the treatment of these rare genetic disorders.

Inhibition of JAK-STAT Signaling with Baricitinib Reduces Inflammation and Improves Cellular Homeostasis in Progeria Cells

Hutchinson-Gilford progeria syndrome (HGPS), a rare premature aging disorder that leads to death at an average age of 14.7 years due to myocardial infarction or stroke, is caused by mutations in the LMNA gene. Nearly 90% of HGPS cases carry the G608G mutation within exon 11 that generates a truncated prelamin A protein “progerin”. Progerin accumulates in HGPS cells and induces premature senescence at the cellular and organismal levels. Children suffering from HGPS develop numerous clinical features that overlap with normal aging, including atherosclerosis, arthritis, hair loss and lipodystrophy. To determine whether an aberrant signaling pathway might underlie the development of these four diseases (atherosclerosis, arthritis, hair loss and lipodystrophy), we performed a text mining analysis of scientific literature and databases. We found a total of 17 genes associated with all four pathologies, 14 of which were linked to the JAK1/2-STAT1/3 signaling pathway. We report that the inhibition of the JAK-STAT pathway with baricitinib, a Food and Drug Administration-approved JAK1/2 inhibitor, restored cellular homeostasis, delayed senescence and decreased proinflammatory markers in HGPS cells. Our ex vivo data using human cell models indicate that the overactivation of JAK-STAT signaling mediates premature senescence and that the inhibition of this pathway could show promise for the treatment of HGPS and age-related pathologies.

Dysfunction of iPSC-derived endothelial cells in human Hutchinson-Gilford progeria syndrome

Children with Hutchinson-Gilford progeria syndrome (HGPS) succumb to myocardial infarction and stroke in their teen years. Endothelial dysfunction is an early event in more common forms of atherosclerosis. Endothelial pathobiology may contribute to HGPS, but a comprehensive characterization of endothelial function in HGPS has not been performed. iPSCs derived from fibroblasts of HGPS patients or unaffected relatives were differentiated into endothelial cells (ECs). Immunofluorescent signal of the pluripotent stem cell markers SSEA4, Oct4, Sox2 and TRAI-60 was similar in HGPS or control iPSCs. Following the differentiation, FACS analysis and immunocytochemistry for CD31 and CD144 revealed a smaller percentage of ECs from HGPS iPSCs. Immunostaining for Lamin A revealed nuclear dysmorphology in HGPS iPSC-ECs. Furthermore, these cells were significantly larger and rounded, and they proliferated less, features which are typical of senescent endothelial cells. HGPS iPSC-ECs manifested less Dil-Ac-LDL uptake; less DAF-2DA staining for nitric oxide generation and formed fewer networks in matrigel in vitro. In immunodeficient mice injected with iPSC-ECs, HGPS iPSC-ECs generated a sparser vascular network compared to the control, with reduced capillary number. Telomere length (T/S ratio) of HGPS iPSC-EC was reduced as assessed by mmqPCR. iPSC-ECs derived from HGPS patients have dysmorphic appearance, abnormal nuclear morphology, shortened telomeres, reduced replicative capacity and impaired functions in vitro and in vivo. Targeting the endothelial abnormality in patients with HGPS may provide a new therapeutic avenue for the treatment of this condition. Abbreviations: HGPS: Hutchinson-Gilford progeria syndrome; ZMPSTE24: Zinc metallopeptidase STE24; FTI: Farnesyltransferase inhibitors; VSMCs: Vascular smooth muscle cells; iPSC: Induced pluripotent stem cells; EC: Endothelial cells; hTERT: Human telomerase reverse transcriptase; VEGF: vascular endothelial growth factor; DAF-FM DA: 3-Amino, 4-aminomethyl-2',7'-difluorofluorescein diacetate; BMP4: Bone Morphogenetic Protein 4; mmqPCR: mono chrome multiplex PCR; SCG: single-copy gene; CSI: Cell shape index.

Mouse Models of Accelerated Cellular Senescence

Senescent cells accumulate in multiple tissues as virtually all vertebrate organisms age. Senescence is a highly conserved response to many forms of cellular stress intended to block the propagation of damaged cells. Senescent cells have been demonstrated to play a causal role in aging via their senescence-associated secretory phenotype and by impeding tissue regeneration. Depletion of senescent cells either through genetic or pharmacologic methods has been demonstrated to extend murine lifespan and delay the onset of age-related diseases. Measuring the burden and location of senescent cells in vivo remains challenging, as there is no marker unique to senescent cells. Here, we describe multiple methods to detect the presence and extent of cellular senescence in preclinical models, with a special emphasis on murine models of accelerated aging that exhibit a more rapid onset of cellular senescence.

Murine models of accelerated aging and musculoskeletal disease

The primary risk factor for most musculoskeletal diseases, including osteoarthritis, osteoporosis and sarcopenia, is aging. To treat the diverse types of musculoskeletal diseases and pathologies, targeting their root cause, the aging process itself, has the potential to slow or prevent multiple age-related musculoskeletal conditions simultaneously. However, the development of approaches to delay onset of age related diseases, including musculoskeletal pathologies, has been slowed by the relatively long lifespan of rodent models of aging. Thus, to expedite the development of therapeutic approaches for age-related musculoskeletal disease, the implementation of mouse models of accelerated musculoskeletal aging are of great utility. Currently there are multiple genetically diverse mouse models that mirror certain aspects of normal human and mouse aging. Here, we provide a review of some of the most relevant murine models of accelerated aging that mimic many aspects of natural musculoskeletal aging, highlighting their relative strengths and weaknesses. Importantly, these murine models of accelerated aging recapitulate phenotypes of musculoskeletal age-related decline observed in humans.

Extraskeletal Calcifications in Hutchinson-Gilford Progeria Syndrome

PURPOSE

Children with Hutchinson-Gilford progeria syndrome (HGPS), a rare premature aging disease, exhibit extraskeletal calcifications detected by radiographic analysis and on physical examination. The aim of this study was to describe the natural history and pathophysiology of these abnormal calcifications in HGPS, and to determine whether medications and/or supplements tested in clinical trials alter their development.

METHODS

Children from two successive clinical trials administering 1) lonafarnib (n = 26) and 2) lonafarnib + pravastatin + zoledronic acid (n = 37) were studied at baseline (pre-therapy), one year on therapy, and at end-of-therapy (3.3-4.3 years after the baseline visit). Calcium supplementation (oral calcium carbonate) was administered during the first year of the second trial and was subsequently discontinued. Information on calcifications was obtained from physical examinations, radiographs, and serum and urinary biochemical measures. The mineral content of two skin-derived calcifications was determined by x-ray diffraction.

RESULTS

Extraskeletal calcifications were detected radiographically in 12/39 (31%) patients at baseline. The odds of exhibiting calcifications increased with age (p = 0.045). The odds were unaffected by receipt of lonafarnib, pravastatin, and zoledronate therapies. However, administration of calcium carbonate supplementation, in conjunction with all three therapeutic agents, significantly increased the odds of developing calcifications (p = 0.009), with the odds plateauing after the supplement's discontinuation. Composition analysis of calcinosis cutis showed hydroxyapatite similar to bone. Although serum calcium, phosphorus, and parathyroid hormone (PTH) were within normal limits at baseline and on-therapy, PTH increased significantly after lonafarnib initiation (p < 0.001). Both the urinary calcium/creatinine ratio and tubular reabsorption of phosphate (TRP) were elevated at baseline in 22/39 (56%) and 31/37 (84%) evaluable patients, respectively, with no significant changes while on-therapy. The mean calcium × phosphorus product (Ca × Pi) was within normal limits, but plasma magnesium decreased over both clinical trials. Fibroblast growth factor 23 (FGF23) was lower compared to age-matched controls (p = 0.03).

CONCLUSIONS

Extraskeletal calcifications increased with age in children with HGPS and were composed of hydroxyapatite. The urinary calcium/creatinine ratio and TRP were elevated for age while FGF23 was decreased. Magnesium decreased and PTH increased after lonafarnib therapy which may alter the ability to mobilize calcium. These findings demonstrate that children with HGPS with normal renal function and an unremarkable Ca × Pi develop extraskeletal calcifications by an unidentified mechanism that may involve decreased plasma magnesium and FGF23. Calcium carbonate accelerated their development and is, therefore, not recommended for routine supplementation in these children.

Genomic instability and innate immune responses to self-DNA in progeria

In the last decade, we have seen increasing evidence of the importance of structural nuclear proteins such as lamins in nuclear architecture and compartmentalization of genome function and in the maintenance of mechanical stability and genome integrity. With over 400 mutations identified in the LMNA gene (encoding for A-type lamins) associated with more than ten distinct degenerative disorders, the role of lamins as genome caretakers and the contribution of lamins dysfunction to disease are unarguable. However, the molecular mechanisms whereby lamins mutations cause pathologies remain less understood. Here, we review pathways and mechanisms recently identified as playing a role in the pathophysiology of laminopathies, with special emphasis in Hutchinson Gilford Progeria Syndrome (HGPS). This devastating incurable accelerated aging disease is caused by a silent mutation in the LMNA gene that generates a truncated lamin A protein "progerin" that exerts profound cellular toxicity and organismal decline. Patients usually die in their teens due to cardiovascular complications such as myocardial infarction or stroke. To date, there are no efficient therapies that ameliorate disease progression, stressing the need to understand molecularly disease mechanisms that can be targeted therapeutically. We will summarize data supporting that replication stress is a major cause of genomic instability in laminopathies, which contributes to the activation of innate immune responses to self-DNA that in turn accelerate the aging process.

A novel elastin gene frameshift mutation in a Russian family with cutis laxa: a case report

Background

Cutis laxa (CL) is a rare connective tissue disorder characterized by loose, redundant, inelastic and wrinkled skin. Patients develop a prematurely aged appearance. Inheritance can be autosomal dominant or autosomal recessive. The X-linked form is now classified in the group of copper transport diseases. Autosomal dominant CL is characterized by wrinkled, redundant and sagging, inelastic skin and in some cases is associated with internal organ involvement.

Case presentation

We report a familial case of autosomal dominant CL, which includes a 33-year-old woman and her 11-year-old son with dry, thin and wrinkled skin that appeared prematurely aged. No serious involvement of internal organs was found. In both patients, we identified novel heterozygous mutation c.2323delG (p.Ala775fs) in exon 34 of elastin transcript NM_001278939.1. Similar frameshift mutations in the last exons of elastin gene were previously reported in patients with autosomal dominant CL.

Conclusions

Our results show a novel frameshift mutation that was found in patients with cutis laxa. Exome sequencing is effective and useful technology for properly diagnosis of diseases with similar phenotype to ensure proper treatment is provided.

Fisetin is a senotherapeutic that extends health and lifespan

BACKGROUND

Senescence is a tumor suppressor mechanism activated in stressed cells to prevent replication of damaged DNA. Senescent cells have been demonstrated to play a causal role in driving aging and age-related diseases using genetic and pharmacologic approaches. We previously demonstrated that the combination of dasatinib and the flavonoid quercetin is a potent senolytic improving numerous age-related conditions including frailty, osteoporosis and cardiovascular disease. The goal of this study was to identify flavonoids with more potent senolytic activity.

METHODS

A panel of flavonoid polyphenols was screened for senolytic activity using senescent murine and human fibroblasts, driven by oxidative and genotoxic stress, respectively. The top senotherapeutic flavonoid was tested in mice modeling a progeroid syndrome carrying a p16INK4a-luciferase reporter and aged wild-type mice to determine the effects of fisetin on senescence markers, age-related histopathology, disease markers, health span and lifespan. Human adipose tissue explants were used to determine if results translated.

FINDINGS

Of the 10 flavonoids tested, fisetin was the most potent senolytic. Acute or intermittent treatment of progeroid and old mice with fisetin reduced senescence markers in multiple tissues, consistent with a hit-and-run senolytic mechanism. Fisetin reduced senescence in a subset of cells in murine and human adipose tissue, demonstrating cell-type specificity. Administration of fisetin to wild-type mice late in life restored tissue homeostasis, reduced age-related pathology, and extended median and maximum lifespan.

INTERPRETATION

The natural product fisetin has senotherapeutic activity in mice and in human tissues. Late life intervention was sufficient to yield a potent health benefit. These characteristics suggest the feasibility to translation to human clinical studies. FUND: NIH grants P01 AG043376 (PDR, LJN), U19 AG056278 (PDR, LJN, WLL), R24 AG047115 (WLL), R37 AG013925 (JLK), R21 AG047984 (JLK), P30 DK050456 (Adipocyte Subcore, JLK), a Glenn Foundation/American Federation for Aging Research (AFAR) BIG Award (JLK), Glenn/AFAR (LJN, CEB), the Ted Nash Long Life and Noaber Foundations (JLK), the Connor Group (JLK), Robert J. and Theresa W. Ryan (JLK), and a Minnesota Partnership Grant (AMAY-UMN#99)-P004610401-1 (JLK, EAA).

ERCC1-deficient cells and mice are hypersensitive to lipid peroxidation

Lipid peroxidation (LPO) products are relatively stable and abundant metabolites, which accumulate in tissues of mammals with aging, being able to modify all cellular nucleophiles, creating protein and DNA adducts including crosslinks. Here, we used cells and mice deficient in the ERCC1-XPF endonuclease required for nucleotide excision repair and the repair of DNA interstrand crosslinks to ask if specifically LPO-induced DNA damage contributes to loss of cell and tissue homeostasis. Ercc1^-/- mouse embryonic fibroblasts were more sensitive than wild-type (WT) cells to the LPO products: 4-hydroxy-2-nonenal (HNE), crotonaldehyde and malondialdehyde. ERCC1-XPF hypomorphic mice were hypersensitive to CCl₄ and a diet rich in polyunsaturated fatty acids, two potent inducers of endogenous LPO. To gain insight into the mechanism of how LPO influences DNA repair-deficient cells, we measured the impact of the major endogenous LPO product, HNE, on WT and Ercc1^-/- cells. HNE inhibited proliferation, stimulated ROS and LPO formation, induced DNA base damage, strand breaks, error-prone translesion DNA synthesis and cellular senescence much more potently in Ercc1^-/- cells than in DNA repair-competent control cells. HNE also deregulated base excision repair and energy production pathways. Our observations that ERCC1-deficient cells and mice are hypersensitive to LPO implicates LPO-induced DNA damage in contributing to cellular demise and tissue degeneration, notably even when the source of LPO is dietary polyunsaturated fats.

Pubertal Progression in Female Adolescents with Progeria

STUDY OBJECTIVE

This study identified the prevalence of menarche and coincident sexual characteristics in female adolescents with Hutchinson-Gilford Progeria Syndrome (HGPS).

DESIGN

Data were examined to determine the prevalence of menarche in female adolescents older than 12 years; all were participants in clinical trials between 2007 and 2016.

SETTING

Pediatric hospital in Boston, Massachusetts.

PARTICIPANTS

Fifteen female adolescents, median age 15 (range, 12.0-20.3) years with a confirmed diagnosis of HGPS.

INTERVENTIONS AND MAIN OUTCOME MEASURES

Report of menarche, anthropometric and serum hormonal measures, Tanner pubertal staging, and body composition using dual-energy x-ray absorptiometry.

RESULTS

Nine of 15 (60%) participants reported spontaneous menarche at a median age of 14.4 years (range, 12.0-16.5 years). In those experiencing menarche vs not, median age was older (16.5 vs 13.6 years; P = .02), whereas body mass index did not differ (10.5 vs 10.4; P = .53) nor percentage body fat (19.4% vs. 19.3%; P = .98) or serum leptin levels (0.40 vs 0.40 ng/mL; P = .23). Among those who achieved menarche, 2 of 9 (22%) had Tanner II breast development and 2 of 9 (22%) exhibited Tanner II Pubic hair, all reflecting minimal pubertal development. Only early signs of puberty were similarly seen in the non-menstruating group, including 1 of 6 (17%) with Tanner II breasts and 2 of 6 (33%) with Tanner II pubic hair, and Tanner staging did not differ between those who reported menarche vs those who did not (each P = 1.0). None of the participants achieved Tanner IV or V thelarche over the course of the study.

CONCLUSION

Menarche was achieved in more than half of adolescent girls with HGPS, in the setting of little to no physical signs of pubertal development and minimal body fat.

Lamins and Lamin-Associated Proteins in Gastrointestinal Health and Disease

The nuclear lamina is a multi-protein lattice composed of A- and B-type lamins and their associated proteins. This protein lattice associates with heterochromatin and integral inner nuclear membrane proteins, providing links among the genome, nucleoskeleton, and cytoskeleton. In the 1990s, mutations in EMD and LMNA were linked to Emery-Dreifuss muscular dystrophy. Since then, the number of diseases attributed to nuclear lamina defects, including laminopathies and other disorders, has increased to include more than 20 distinct genetic syndromes. Studies of patients and mouse genetic models have pointed to important roles for lamins and their associated proteins in the function of gastrointestinal organs, including liver and pancreas. We review the interactions and functions of the lamina in relation to the nuclear envelope and genome, the ways in which its dysfunction is thought to contribute to human disease, and possible avenues for targeted therapies.

Nucleoplasmic lamins define growth-regulating functions of lamina-associated polypeptide 2α in progeria cells

A-type lamins are components of the peripheral nuclear lamina but also localize in the nuclear interior in a complex with lamina-associated polypeptide (LAP) 2α. Loss of LAP2α and nucleoplasmic lamins in wild-type cells increases cell proliferation, but in cells expressing progerin (a mutant lamin A that causes Hutchinson-Gilford progeria syndrome), low LAP2α levels result in proliferation defects. Here, the aim was to understand the molecular mechanism governing how relative levels of LAP2α, progerin and nucleoplasmic lamins affect cell proliferation. Cells from progeria patients and inducible progerin-expressing cells expressing low levels of progerin proliferate faster than wild-type or lamin A-expressing control cells, and ectopic expression of LAP2α impairs proliferation. In contrast, cells expressing high levels of progerin and lacking lamins in the nuclear interior proliferate more slowly, and ectopic LAP2α expression enhances proliferation. However, simultaneous expression of LAP2α and wild-type lamin A or an assembly-deficient lamin A mutant restored the nucleoplasmic lamin A pool in these cells and abolished the growth-promoting effect of LAP2α. Our data show that LAP2α promotes or inhibits proliferation of progeria cells depending on the level of A-type lamins in the nuclear interior.This article has an associated First Person interview with the first author of the paper.

In Vivo Transient and Partial Cell Reprogramming to Pluripotency as a Therapeutic Tool for Neurodegenerative Diseases

In theory, human diseases in which a specific cell type degenerates, such as neurodegenerative diseases, can be therapeutically addressed by replacement of the lost cells. The classical strategy for cell replacement is exogenous cell transplantation, but now, cell replacement can also be achieved with in situ reprogramming. Indeed, many of these disorders are age-dependent, and "rejuvenating" strategies based on cell epigenetic modifications are a possible approach to counteract disease progression. In this context, transient and/or partial reprogramming of adult somatic cells towards pluripotency can be a promising tool for neuroregeneration. Temporary and controlled in vivo overexpression of Yamanaka reprogramming factors (Oct3/4, Sox2, Klf4, and c-Myc (OSKM)) has been proven feasible in different experimental settings and could be employed to facilitate in situ tissue regeneration; this regeneration can be accomplished either by producing novel stem/precursor cells, without the challenges posed by exogenous cell transplantation, or by changing the epigenetic adult cell signature to the signature of a younger cell. The risk of this procedure resides in the possible lack of perfect control of the process, carrying a potential oncogenic or unexpected cell phenotype hazard. Recent studies have suggested that these limits can be overcome by a tightly controlled cyclic regimen of short-term OSKM expression in vivo that prevents full reprogramming to the pluripotent state and avoids both tumorigenesis and the presence of unwanted undifferentiated cells. On the other hand, this strategy can enhance tissue regeneration for therapeutic purposes in aging-related neurological diseases as well. These data could open the path to further research on the therapeutic potential of in vivo reprogramming in regenerative medicine.

Hallmarks of progeroid syndromes: lessons from mice and reprogrammed cells

Ageing is a process that inevitably affects most living organisms and involves the accumulation of macromolecular damage, genomic instability and loss of heterochromatin. Together, these alterations lead to a decline in stem cell function and to a reduced capability to regenerate tissue. In recent years, several genetic pathways and biochemical mechanisms that contribute to physiological ageing have been described, but further research is needed to better characterize this complex biological process. Because premature ageing (progeroid) syndromes, including progeria, mimic many of the characteristics of human ageing, research into these conditions has proven to be very useful not only to identify the underlying causal mechanisms and identify treatments for these pathologies, but also for the study of physiological ageing. In this Review, we summarize the main cellular and animal models used in progeria research, with an emphasis on patient-derived induced pluripotent stem cell models, and define a series of molecular and cellular hallmarks that characterize progeroid syndromes and parallel physiological ageing. Finally, we describe the therapeutic strategies being investigated for the treatment of progeroid syndromes, and their main limitations.

Summary: This Review defines the molecular and cellular hallmarks of progeroid syndromes according to the main cellular and animal models, and discusses the therapeutic strategies developed to date.

Are there Different Kinds of Aging?

BACKGROUND

Most syndromes of accelerated aging are caused by mutations affecting the integrity of the genetic material. Among them, the most studied is Werner's syndrome, "adult progeria", caused by a recessive autosomal mutation with a frequency of 1 in 10 million, which affects a helicase involved in DNA repair. In Werner syndrome, there is a loss of heterochromatin, though the stability of heterochromatin is also affected in "normal" aging. The Hutchinson-Gilford Progeria Syndrome (HGPS), "child progeria", has an even lower frequency. In most cases, it is caused by a point mutation of a gene coding a protein in the nuclear envelope, lamin A.

OBJECTIVES

HGPS may provide valuable insights into the aging process. The symptoms of this condition do not entirely overlap with those of "normal" aging.

METHOD

A critical analysis of the accelerated aging syndromes may explain what aging is, and also why some tissues and organs age at accelerated rates as compared to other tissues.

RESULTS

In this article, we will discuss the implications of HGPS and other accelerated aging syndromes in the light of the biochemical hypothesis of aging we advanced. According to this hypothesis, some reactions are less stimulated and diminish in time, affecting not only specific biochemical functions, but cellular energy, and therefore its capacity for synthesis.

CONCLUSION

Besides, a new vision on aging, possible therapeutic strategies for these conditions and others, with similar mechanisms, are also presented.

Non-syndromic cardiac progeria in a patient with the rare pathogenic p.Asp300Asn variant in the LMNA gene

Background

Mutations in LMNA gene, encoding Lamin A/C, cause a diverse array of phenotypes, collectively referred to as laminopathies. The most common manifestation is dilated cardiomyopathy (DCM), occurring in conjunction with variable skeletal muscle involvement but without involvement of the coronary arteries. Much less commonly, LMNA mutations cause progeroid syndromes, whereby an early-onset coronary artery disease (CAD) is the hallmark of the disease. We report a hitherto unreported compound cardiac phenotype, dubbed as “non-syndromic cardiac progeria”, in a young patient who carried a rare pathogenic variant in the LMNA gene and developed progressive degeneration of various cardiac structures, as seen in the elderly. The phenotype resembled the progeroid syndromes, except that it was restricted to the heart and did not involve other organs.

Case presentation

The patient was a well-developed Caucasian female who presented at age 29 years with an acute myocardial infarction (MI) and was found to have extensive CAD. She had none of the conventional risk factors for atherosclerosis. She underwent coronary artery bypass surgery but continued to require multiple percutaneous coronary interventions for symptomatic obstructive coronary lesions. During the course of next 10 years, she developed mitral regurgitation, degenerative mitral and aortic valve diseases, atrial flutter, and progressive conduction defects. She died from progressive heart failure with predominant involvement of the right ventricle and severe tricuspid regurgitation. Cardiac phenotype in this young patient resembled degenerative cardiac diseases of the elderly and the progeroid syndromes. However, in contrast to the progeroid syndromes, the phenotype was restricted to the heart and did not involve other organs. Thus, the phenotype was dubbed as a non-syndromic cardiac progeria.

Genetic screening of several cardiomyopathy genes, including LMNA, which is a causal gene for progeroid syndromes, led to identification of a very rare pathogenic p.Asp300Asn variant in the LMNA gene.

Conclusions

We infer that the LMNA p.Asp300Asn mutation is pathogenic in non-syndromic cardiac progeria. Mutations involving codon 300 in the LMNA gene have been associated with progeroid syndromes involving multiple organs. Collectively, the data provide credence to the causal role of p.Asp300Asn mutation in the pathogenesis of non-syndromic cardiac progeria.

Electronic supplementary material

The online version of this article (10.1186/s12881-017-0480-x) contains supplementary material, which is available to authorized users.

Progeria: an extremely unusual disorder

Hutchinson-Gilford progeria syndrome, also known as progeria, is an extremely rare disorder with an incidence rate of 1 in 8 million. It occurs sporadically, and patients suffering from this syndrome usually exhibit premature ageing. It has an autosomal recessive inheritance with a slight male predominance. The affected children usually die early with an average life span of 13.4 years. The most common cause of death in such patients is a cardio-vascular abnormality such as myocardial infarction. We present a rare case of progeria in an 8-year-old boy who was diagnosed clinically and was referred to our department for a skeletal survey. Almost all of the typical radiological findings were present in this case, which further confirmed the clinical diagnosis of progeria.

Redox imbalance in a model of rat mimicking Hutchinson-Gilford progeria syndrome

Although several etiological factors contribute to the complexity of the aging process, the ultimate component of macromolecular damage and consequent cell death involves the altered redox balance inclined towards increased ROS production and/or decreased antioxidant protection. Given that, the chronic dihydrotachysterol (DHT) intoxication in rats induce Hutchinson Gilford progeria like syndrome, the present study provides the evidence for altered redox balance as evidenced by alteration in parameters of oxidative stress in blood plasma and erythrocytes including MDA, GSH, FRAP AOPP PMRS, AGEs, AChE and osmotic fragility which substantiate the suitability of the model for aging studies.

Nucleocytoplasmic transport in cells with progerin-induced defective nuclear lamina

Recent data indicate that nuclear lamina (NL) plays a relevant role in many fundamental cellular functions. The peculiar role of NL in cells is dramatically demonstrated by the Hutchinson-Gilford progeria syndrome (HGPS), an inherited laminopathy that causes premature, rapid aging shortly after birth. In HGPS, a mutant form of Lamin A (progeria) leads to a dysmorphic NL structure, but how this perturbation is transduced into cellular changes is still largely unknown. Owing to the close structural relationship between NL and the Nuclear Pore Complex (NPC), in this work we test whether HGPS affects passive and active nucleo-cytoplasmic shuttling of cargoes by means of an established model based of fluorescence recovery after photobleaching. Our findings clearly demonstrate that dysmorphic NL is decoupled from the dynamic characteristics of passive and active transport towards and from the nucleus, as well as from the binding affinity of transport protein mediators.

Hutchinson-Gilford Progeria Syndrome: A Premature Aging Disease

Progeria is sporadic, very rare, autosomal dominant, deadly childhood disorder. It is one of the progeroid syndromes also known as Hutchinson-Gilford progeria syndrome (HGPS). Aging is a developmental process that begins with fertilization and ends up with death involving a lot of environmental and genetic factors. The disease firstly involves premature aging and then death from complications of atherosclerosis such as myocardial infarction, stroke, atherosclerosis, or heart failure. The lifespan of the patient is normally up to teen age or early twenties. It is usually not inherited because a patient normally dies before the age of reproduction. The most important genetic linkage between progeria and aging is shortening of telomere ends with each replication cycle. The patients are normally observed to have extremely short telomeres. Currently, 90% of the patients are said to have de novo point mutations in the LMNA gene that substitute cytosine with thymine and have been found in individuals with HGPS. Lmna encodes lamins A and C, and the A-type lamins have important structural function in the nuclear envelope. The most common type of HGPS mutation is located at codon 608 (G608G). It could not be diagnosed at birth, but after the age of 2 years, visible, prominent symptoms can be observed. Still, lot of research is needed to solve this mystery; hopefully, future research on HGPS would provide important clues for progeria and other fatal age-related disorders.

Mammalian telomeres and their partnership with lamins

Chromosome ends are complex structures, which require a panel of factors for their elongation, replication, and protection. We describe here the mechanics of mammalian telomeres, dynamics and maintainance in relation to lamins. Multiple biochemical connections, including association of telomeres to the nuclear envelope and matrix, of telomeric proteins to lamins, and of lamin-associated proteins to chromosome ends, underline the interplay between lamins and telomeres. Paths toward senescence, such as defective telomere replication, altered heterochromatin organization, and impaired DNA repair, are common to lamins' and telomeres' dysfunction. The convergence of phenotypes can be interpreted through a model of dynamic, lamin-controlled functional platforms dedicated to the function of telomeres as fragile sites. The features of telomeropathies and laminopathies, and of animal models underline further overlapping aspects, including the alteration of stem cell compartments. We expect that future studies of basic biology and on aging will benefit from the analysis of this telomere-lamina interplay.

Cockayne syndrome: Clinical features, model systems and pathways

Cockayne syndrome (CS) is a disorder characterized by a variety of clinical features including cachectic dwarfism, severe neurological manifestations including microcephaly and cognitive deficits, pigmentary retinopathy, cataracts, sensorineural deafness, and ambulatory and feeding difficulties, leading to death by 12 years of age on average. It is an autosomal recessive disorder, with a prevalence of approximately 2.5 per million. There are several phenotypes (1-3) and two complementation groups (CSA and CSB), and CS overlaps with xeroderma pigmentosum (XP). It has been considered a progeria, and many of the clinical features resemble accelerated aging. As such, the study of CS affords an opportunity to better understand the underlying mechanisms of aging. The molecular basis of CS has traditionally been ascribed to defects in transcription and transcription-coupled nucleotide excision repair (TC-NER). However, recent work suggests that defects in base excision DNA repair and mitochondrial functions may also play key roles. This opens up the possibility for molecular interventions in CS, and by extrapolation, possibly in aging.

Mechanics in human fibroblasts and progeria: Lamin A mutation E145K results in stiffening of nuclei

The lamina is a filamentous meshwork beneath the inner nuclear membrane that confers mechanical stability to nuclei. The E145K mutation in lamin A causes Hutchinson-Gilford progeria syndrome (HGPS). It affects lamin filament assembly and induces profound changes in the nuclear architecture. Expression of wild-type and E145K lamin A in Xenopus oocytes followed by atomic force microscopy (AFM) probing of isolated oocyte nuclei has shown significant changes in the mechanical properties of the lamina. Nuclei of oocytes expressing E145K lamin A are stiffer than those expressing wild-type lamin A. Here we present mechanical measurements by AFM on dermal fibroblasts obtained from a 4-year-old progeria patient bearing the E145K lamin A mutation and compared it to fibroblasts obtained from 2 healthy donors of 10 and 61 years of age, respectively. The abnormal shape of nuclei expressing E145K lamin A was analyzed by fluorescence microscopy. Lamina thickness was measured using electron micrographs. Fluorescence microscopy showed alterations in the actin network of progeria cells. AFM probing of whole dermal fibroblasts did not demonstrate significant differences in the elastic moduli of nuclear and cytoplasmic cell regions. In contrast, AFM measurements of isolated nuclei showed that nuclei of progeria and old person's cells are significantly stiffer than those of the young person, indicating that the process of aging, be it natural or abnormal, increases nuclear stiffness. Our results corroborate AFM data obtained using Xenopus oocyte nuclei and prove that the presence of E145K lamin A abnormally increases nuclear stiffness.

NANOG Reverses the Myogenic Differentiation Potential of Senescent Stem Cells by Restoring ACTIN Filamentous Organization and SRF-Dependent Gene Expression

Cellular senescence as a result of organismal aging or progeroid diseases leads to stem cell pool exhaustion hindering tissue regeneration and contributing to the progression of age related disorders. Here we discovered that ectopic expression of the pluripotent factor NANOG in senescent or progeroid myogenic progenitors reversed cellular aging and restored completely the ability to generate contractile force. To elicit its effects, NANOG enabled reactivation of the ROCK and Transforming Growth Factor (TGF)-β pathways-both of which were impaired in senescent cells-leading to ACTIN polymerization, MRTF-A translocation into the nucleus and serum response factor (SRF)-dependent myogenic gene expression. Collectively our data reveal that cellular senescence can be reversed and provide a novel strategy to regain the lost function of aged stem cells without reprogramming to the pluripotent state. Stem Cells 2017;35:207-221.

Molecular insights into the premature aging disease progeria

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare premature aging disease presenting many features resembling the normal aging process. HGPS patients die before the age of 20 years due to cardiovascular problems and heart failure. HGPS is linked to mutations in the LMNA gene encoding the intermediate filament protein lamin A. Lamin A is a major component of the nuclear lamina, a scaffold structure at the nuclear envelope that defines mechanochemical properties of the nucleus and is involved in chromatin organization and epigenetic regulation. Lamin A is also present in the nuclear interior where it fulfills lamina-independent functions in cell signaling and gene regulation. The most common LMNA mutation linked to HGPS leads to mis-splicing of the LMNA mRNA and produces a mutant lamin A protein called progerin that tightly associates with the inner nuclear membrane and affects the dynamic properties of lamins. Progerin expression impairs many important cellular processes providing insight into potential disease mechanisms. These include changes in mechanosignaling, altered chromatin organization and impaired genome stability, and changes in signaling pathways, leading to impaired regulation of adult stem cells, defective extracellular matrix production and premature cell senescence. In this review, we discuss these pathways and their potential contribution to the disease pathologies as well as therapeutic approaches used in preclinical and clinical tests.

A mutation abolishing the ZMPSTE24 cleavage site in prelamin A causes a progeroid disorder

In 1994 in the Journal of Cell Science, Hennekes and Nigg reported that changing valine to arginine at the endoproteolytic cleavage site in chicken prelamin A abolishes its conversion to lamin A. The consequences of this mutation in an organism have remained unknown. We now report that the corresponding mutation in a human subject leads to accumulation of prelamin A and causes a progeroid disorder. Next generation sequencing of the subject and her parents' exomes identified a de novo mutation in the lamin A/C gene (LMNA) that resulted in a leucine to arginine amino acid substitution at residue 647 in prelamin A. The subject's fibroblasts accumulated prelamin A, a farnesylated protein, which led to an increased percentage of cultured cells with morphologically abnormal nuclei. Treatment with a protein farnesyltransferase inhibitor improved abnormal nuclear morphology. This case demonstrates that accumulation of prelamin A, independent of the loss of function of ZMPSTE24 metallopeptidase that catalyzes processing of prelamin A, can cause a progeroid disorder and that a cell biology assay could be used in precision medicine to identify a potential therapy.

Pluripotent stem cells to model Hutchinson-Gilford progeria syndrome (HGPS): Current trends and future perspectives for drug discovery

Progeria, or Hutchinson-Gilford progeria syndrome (HGPS), is a rare, fatal genetic disease characterized by an appearance of accelerated aging in children. This syndrome is typically caused by mutations in codon 608 (p.G608G) of the LMNA, leading to the production of a mutated form of lamin A precursor called progerin. In HGPS, progerin accumulates in cells causing progressive molecular defects, including nuclear shape abnormalities, chromatin disorganization, damage to DNA and delays in cell proliferation. Here we report how, over the past five years, pluripotent stem cells have provided new insights into the study of HGPS and opened new original therapeutic perspectives to treat the disease.