The accumulation of un-repairable DNA damage in laminopathy progeria fibroblasts is caused by ROS generation and is prevented by treatment with N-acetyl cysteine

Nuclear lamins and oxidative stress in cell proliferation and longevity

In mammalian cells, the nuclear lamina is composed of a complex fibrillar network associated with the inner membrane of the nuclear envelope. The lamina provides mechanical support for the nucleus and functions as the major determinant of its size and shape. At its innermost aspect it associates with peripheral components of chromatin and thereby contributes to the organization of interphase chromosomes. The A- and B-type lamins are the major structural components of the lamina, and numerous mutations in the A-type lamin gene have been shown to cause many types of human diseases collectively known as the laminopathies. These mutations have also been shown to cause a disruption in the normal interactions between the A and B lamin networks. The impact of these mutations on nuclear functions is related to the roles of lamins in regulating various essential processes including DNA synthesis and damage repair, transcription and the regulation of genes involved in the response to oxidative stress. The major cause of oxidative stress is the production of reactive oxygen species (ROS), which is critically important for cell proliferation and longevity. Moderate increases in ROS act to initiate signaling pathways involved in cell proliferation and differentiation, whereas excessive increases in ROS cause oxidative stress, which in turn induces cell death and/or senescence. In this review, we cover current findings about the role of lamins in regulating cell proliferation and longevity through oxidative stress responses and ROS signaling pathways. We also speculate on the involvement of lamins in tumor cell proliferation through the control of ROS metabolism.

Effects of dinuclear berenil-platinum(II) complexes on fibroblasts redox status

PURPOSE

Platinum(II) complex anticarcinogenic mechanisms are associated with changes in the cellular redox status of cancer as well as healthy cells. Therefore, the goal of the present study was to investigate oxidative modifications in cellular components following fibroblast exposure to novel dinuclear berenil-platinum(II) complexes.

MATERIAL AND METHOD

ROS levels, antioxidant parameters level/activity, and damage to DNA, lipids, and proteins, including pro-apoptotic and anti-apoptotic factors in human skin fibroblasts following berenil-platinum(II) complex treatments i.e. Pt2(isopropylamine)4(berenil)2, Pt2(piperazine)4(berenil)4, Pt2(2-picoline)4(berenil)2, Pt2(3-picoline)4(berenil)2, and Pt2(4- picoline)4(berenil)2 were examined.

RESULTS

Treatment of fibroblasts with platinum(II) complexes has shown that all compounds enhance total ROS and superoxide anion generation as well as change the activity of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase and decrease in the level of non-enzymatic antioxidants (GSH, vitamin C, E and A). Such a situation is conducive to oxidative stress formation and oxidative modifications of cellular macromolecules and to increase in the expression of proapoptotic proteins. Pt2(isopropylamine)4(berenil)2 elicited the most damage, which resulted in oxidative modification of cellular components. The therapeutic use of this complex would cause considerable side effects in patients, therefore the agent lacks drug potential; however Pt2(piperazine)4(berenil)2 and Pt2(2-picoline)4(berenil)2 exhibited reduced redox and increased apoptotic profiles compared to cisplatin.

CONCLUSION

Results of this paper and preliminary data show that Pt2(2-picoline)4(berenil)2 is less dangers than cisplatin to fibroblasts and more disruptive than cisplatin to breast cancer cell metabolism, and therefore it is a promising candidate for use in future anticancer drug strategies.

Lamins are rapamycin targets that impact human longevity: a study in centenarians

The dynamic organisation of the cell nucleus is profoundly modified during growth, development and senescence as a result of changes in chromatin arrangement and gene transcription. A plethora of data suggests that the nuclear lamina is a key player in chromatin dynamics and argues in favour of a major involvement of prelamin A in fundamental mechanisms regulating cellular senescence and organism ageing. As the best model to analyse the role of prelamin A in normal ageing, we used cells from centenarian subjects. We show that prelamin A is accumulated in fibroblasts from centenarians owing to downregulation of its specific endoprotease ZMPSTE24, whereas other nuclear envelope constituents are mostly unaffected and cells do not enter senescence. Accumulation of prelamin A in nuclei of cells from centenarians elicits loss of heterochromatin, as well as recruitment of the inactive form of 53BP1, associated with rapid response to oxidative stress. These effects, including the prelamin-A-mediated increase of nuclear 53BP1, can be reproduced by rapamycin treatment of cells from younger individuals. These data identify prelamin A and 53BP1 as new targets of rapamycin that are associated with human longevity. We propose that the reported mechanisms safeguard healthy ageing in humans through adaptation of the nuclear environment to stress stimuli.

Mechanisms of vascular calcification in CKD-evidence for premature ageing?

Ageing is a potent, independent risk factor for cardiovascular disease. Calcification of the vascular smooth muscle cell (VSMC) layer of the vessel media is a hallmark of vascular ageing. Young patients with chronic kidney disease (CKD) exhibit an extremely high cardiovascular mortality, equivalent to that seen in octogenarians in the general population. Even children on dialysis develop accelerated medial vascular calcification and arterial stiffening, leading to the suggestion that patients with CKD exhibit a 'premature ageing' phenotype. It is now well documented that uraemic toxins, particularly those associated with dysregulated mineral metabolism, can drive VSMC damage and phenotypic changes that promote vascular calcification; epidemiological data suggest that some of these same risk factors associate with cardiovascular mortality in the aged general population. Importantly, emerging evidence suggests that uraemic toxins may promote DNA damage, a key factor driving cellular ageing, and moreover, that these ageing mechanisms may reiterate some of those seen in patients with genetically induced progeric syndromes caused by nuclear lamina disruption. This new knowledge should pave the way for the development of novel therapies that target tissue-specific ageing mechanisms to treat vascular decline in CKD.

Hutchinson-Gilford progeria syndrome through the lens of transcription

Lamins are nuclear intermediate filaments. In addition to their structural roles, they are implicated in basic nuclear functions such as chromatin organization, DNA replication, transcription, DNA repair, and cell-cycle progression. Mutations in human LMNA gene cause several diseases termed laminopathies. One of the laminopathic diseases is Hutchinson-Gilford progeria syndrome (HGPS), which is caused by a spontaneous mutation and characterized by premature aging. HGPS phenotypes share certain similarities with several apparently comparable medical conditions, such as aging and atherosclerosis, with the conspicuous absence of neuronal degeneration and cancer rarity during the short lifespan of the patients. Cell lines from HGPS patients are characterized by multiple nuclear defects, which include abnormal morphology, altered histone modification patterns, and increased DNA damage. These cell lines provide insight into the molecular pathways including senescence that require lamins A and B1. Here, we review recent data on HGPS phenotypes through the lens of transcriptional deregulation caused by lack of functional lamin A, progerin accumulation, and lamin B1 silencing.

Muscular dystrophies share pathogenetic mechanisms with muscle sarcomas

Several lines of recent evidence have opened a new debate on the mechanisms underlying the genesis of rhabdomyosarcoma, a pediatric soft tissue tumor with a widespread expression of muscle-specific markers. In particular, it is increasingly evident that the loss of skeletal muscle integrity observed in some mouse models of muscular dystrophy can favor rhabdomyosarcoma formation. This is especially true in old age. Here, we review these experimental findings and focus on the main molecular and cellular events that can dictate the tumorigenic process in dystrophic muscle, such as the loss of structural or regulatory proteins with tumor suppressor activity, the impaired DNA damage response due to oxidative stress, the chronic inflammation and the conflicting signals arising within the degenerated muscle niche.

Lamin aggregation is an early sensor of porphyria-induced liver injury

Oxidative liver injury during steatohepatitis results in aggregation and transglutaminase-2 (TG2)-mediated crosslinking of the keratin cytoplasmic intermediate filament proteins (IFs) to form Mallory-Denk body (MDB) inclusions. The effect of liver injury on lamin nuclear IFs is unknown, though lamin mutations in several human diseases result in lamin disorganization and nuclear shape changes. We tested the hypothesis that lamins undergo aggregation during oxidative liver injury using two MDB mouse models: (i) mice fed the porphyrinogenic drug 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) and (ii) mice that harbor a mutation in ferrochelatase (fch), which converts protoporphyrin IX to heme. Dramatic aggregation of lamin A/C and B1 was noted in the livers of both models in association with changes in lamin organization and nuclear shape, as determined by immunostaining and electron microscopy. The lamin aggregates sequester other nuclear proteins including transcription factors and ribosomal and nuclear pore components into high molecular weight complexes, as determined by mass-spectrometry and confirmed biochemically. Lamin aggregate formation is rapid and precedes keratin aggregation in fch livers, and is seen in liver explants of patients with alcoholic cirrhosis. Exposure of cultured cells to DDC, protoporphyrin IX or N-methyl-protoporphyrin, or incubation of purified lamins with protoporphyrin IX, also results in lamin aggregation. In contrast, lamin aggregation is ameliorated by TG2 inhibition. Therefore, lamin aggregation is an early sensor of porphyria-associated liver injury and might serve to buffer oxidative stress. The nuclear shape and lamin defects associated with porphyria phenocopy the changes seen in laminopathies and could result in transcriptional alterations due to sequestration of nuclear proteins.

Lipodystrophy-linked LMNA p.R482W mutation induces clinical early atherosclerosis and in vitro endothelial dysfunction

OBJECTIVE

Some mutations in LMNA, encoding A-type lamins, are responsible for Dunnigan-type-familial partial lipodystrophy (FPLD2), with altered fat distribution and metabolism. The high prevalence of early and severe cardiovascular outcomes in these patients suggests that, in addition to metabolic risk factors, FPLD2-associated LMNA mutations could have a direct role on the vascular wall cells.

APPROACH AND RESULTS

We analyzed the cardiovascular phenotype of 19 FPLD2 patients aged >30 years with LMNA p.R482 heterozygous substitutions, and the effects of p.R482W-prelamin-A overexpression in human coronary artery endothelial cells. In 68% of FPLD2 patients, early atherosclerosis was attested by clinical cardiovascular events, occurring before the age of 45 in most cases. In transduced endothelial cells, exogenous wild-type-prelamin-A was correctly processed and localized, whereas p.R482W-prelamin-A accumulated abnormally at the nuclear envelope. Patients' fibroblasts also showed a predominant nuclear envelope distribution with a decreased rate of prelamin-A maturation. Only p.R482W-prelamin-A induced endothelial dysfunction, with decreased production of NO, increased endothelial adhesion of peripheral blood mononuclear cells, and cellular senescence. p.R482W-prelamin-A also induced oxidative stress, DNA damages, and inflammation. These alterations were prevented by treatment of endothelial cells with pravastatin, which inhibits prelamin-A farnesylation, or with antioxidants. In addition, pravastatin allowed the correct relocalization of p.R482W-prelamin-A within the endothelial cell nucleus. These data suggest that farnesylated p.R482W-prelamin-A accumulation at the nuclear envelope is a toxic event, leading to cellular oxidative stress and endothelial dysfunction.

CONCLUSIONS

LMNA p.R482 mutations, responsible for FPLD2, exert a direct proatherogenic effect in endothelial cells, which could contribute to patients' early atherosclerosis.

Changes in vimentin, lamin A/C and mitofilin induce aberrant cell organization in fibroblasts from Fanconi anemia complementation group A (FA-A) patients

Growing number of publication has proved an increasing of cellular function of the Fanconi anemia proteins. To chromosome stability and DNA repair new roles have been attributed to FA proteins in oxidative stress response and homeostasis, immune response and cytokines sensibility, gene expression. Our work shows a new role for FA-A protein: the organization of the cellular structure. By 2D-PAGE of FA-A and correct fibroblasts treated and untreated with H2O2 we identify different expression of protein involved in the structural organization of nucleus, intermediate filaments and mitochondria. Immunofluorescence and electronic microscopy analysis clearly show an already altered cellular structure in normal culture condition and this worsted after oxidative stress. FA-A cell appears structurally prone to physiologic stress and this could explain part of the phenotype of FA cells.

Prelamin A accelerates vascular calcification via activation of the DNA damage response and senescence-associated secretory phenotype in vascular smooth muscle cells

RATIONALE

Vascular calcification is prevalent in the aging population, yet little is known of the mechanisms driving age-associated vascular smooth muscle cell (VSMC) phenotypic change.

OBJECTIVE

To investigate the role of nuclear lamina disruption, a specific hallmark of VSMC aging, in driving VSMC osteogenic differentiation.

METHODS AND RESULTS

Prelamin A, the unprocessed form of the nuclear lamina protein lamin A, accumulated in calcifying human VSMCs in vitro and in vivo, and its overexpression promoted VSMC osteogenic differentiation and mineralization. During VSMC aging in vitro, prelamin A accumulation occurred concomitantly with increased p16 expression and osteogenic differentiation and was associated with increased levels of DNA damage. Microarray analysis showed that DNA damage repair pathways were significantly impaired in VSMCs expressing prelamin A and that chemical inhibition and siRNA depletion of the DNA damage response kinases ataxia-telangiectasia mutated/ataxia-telangiectasia- and Rad3-related effectively blocked VSMC osteogenic differentiation and mineralization. In coculture experiments, prelamin A-expressing VSMCs induced alkaline phosphatase activity in mesenchymal progenitor cells, and this was abrogated by inhibition of ataxia-telangiectasia-mutated signaling, suggesting that DNA damage induces the secretion of pro-osteogenic factors by VSMCs. Cytokine array analysis identified several ataxia-telangiectasia mutated-dependent senescence-associated secretory phenotype factors/cytokines released by prelamin A-positive VSMCs, including the calcification regulators bone morphogenetic protein 2, osteoprotegerin, and interleukin 6.

CONCLUSIONS

Prelamin A promotes VSMC calcification and aging by inducing persistent DNA damage signaling, which acts upstream of VSMC osteogenic differentiation and the senescence-associated secretory phenotype. Agents that target the DNA damage response and prelamin A toxicity may be potential therapies for the treatment of vascular calcification.

How aluminum, an intracellular ROS generator promotes hepatic and neurological diseases: the metabolic tale

Metal pollutants are a global health risk due to their ability to contribute to a variety of diseases. Aluminum (Al), a ubiquitous environmental contaminant is implicated in anemia, osteomalacia, hepatic disorder, and neurological disorder. In this review, we outline how this intracellular generator of reactive oxygen species (ROS) triggers a metabolic shift towards lipogenesis in astrocytes and hepatocytes. This Al-evoked phenomenon is coupled to diminished mitochondrial activity, anerobiosis, and the channeling of α-ketoacids towards anti-oxidant defense. The resulting metabolic reconfiguration leads to fat accumulation and a reduction in ATP synthesis, characteristics that are common to numerous medical disorders. Hence, the ability of Al toxicity to create an oxidative environment promotes dysfunctional metabolic processes in astrocytes and hepatocytes. These molecular events triggered by Al-induced ROS production are the potential mediators of brain and liver disorders.

Oct-1 recruitment to the nuclear envelope in adult-onset autosomal dominant leukodystrophy

Adult-onset autosomal dominant leukodystrophy (ADLD) is a slowly progressive neurological disorder characterised by pyramidal, cerebellar, and autonomic disturbances. Duplication of the LMNB1 gene is the genetic cause of ADLD, yet the pathogenetic mechanism is not defined. In this study, we analysed cells and muscle tissue from three patients affected by ADLD, carrying an extra copy of the LMNB1 gene. Lamin B1 levels were dramatically increased in ADLD nuclei, both in skin fibroblasts and skeletal muscle fibres. Since lamin B1 is known to bind Oct-1, a transcription factor involved in the oxidative stress pathway, we investigated Oct-1 fate in ADLD. Oct-1 recruitment to the nuclear periphery was increased in ADLD cells, while nucleoplasmic localisation of the transcription factor under oxidative stress conditions was reduced. Importantly, lamin B1 degradation occurring in some, but not all ADLD cell lines, slowed down lamin B1 and Oct-1 accumulation. In skeletal muscle, focal disorganisation of sarcomeres was observed, while IIB-myosin heavy chain, an Oct-1 target gene, was under-expressed and rod-containing fibres were formed. These data show that a high degree of regulation of lamin B1 expression is implicated in the different clinical phenotypes observed in ADLD and show that altered Oct-1 nuclear localisation contributes to the disease phenotype.

Potential therapeutic approaches for modulating expression and accumulation of defective lamin A in laminopathies and age-related diseases

Scientific understanding of the genetic components of aging has increased in recent years, with several genes being identified as playing roles in the aging process and, potentially, longevity. In particular, genes encoding components of the nuclear lamina in eukaryotes have been increasingly well characterized, owing in part to their clinical significance in age-related diseases. This review focuses on one such gene, which encodes lamin A, a key component of the nuclear lamina. Genetic variation in this gene can give rise to lethal, early-onset diseases known as laminopathies. Here, we analyze the literature and conduct computational analyses of lamin A signaling and intracellular interactions in order to examine potential mechanisms for altering or slowing down aberrant Lamin A expression and/or for restoring the ratio of normal to aberrant lamin A. The ultimate goal of such studies is to ameliorate or combat laminopathies and related diseases of aging, and we provide a discussion of current approaches in this review.

Generation and characterization of multipotent stem cells from established dermal cultures

Human multipotent skin derived precursor cells (SKPs) are traditionally sourced from dissociated dermal tissues; therefore, donor availability may become limiting. Here we demonstrate that both normal and diseased adult human dermal fibroblasts (DF) pre-cultured in conventional monolayers are capable of forming SKPs (termed m-SKPs). Moreover, we show that these m-SKPs can be passaged and that cryopreservation of original fibroblast monolayer cultures does not reduce m-SKP yield; however, extensive monolayer passaging does. Like SKPs generated from dissociated dermis, these m-SKPs expressed nestin, fibronectin and versican at the protein level. At the transcriptional level, m-SKPs derived from normal adult human DF, expressed neural crest stem cell markers such as p75NTR, embryonic stem cell markers such as Nanog and the mesenchymal stem cell marker Dermo-1. Furthermore, appropriate stimuli induced m-SKPs to differentiate down either mesenchymal or neural lineages resulting in lipid accumulation, calcification and S100β or β-III tubulin expression (with multiple processes). m-SKP yield was greater from neonatal foreskin cultures compared to those from adult DF cultures; however, the former showed a greater decrease in m-SKP forming capacity after extensive monolayer passaging. m-SKP yield was greater from adult DF cultures expressing more alpha-smooth muscle actin (αSMA). In turn, elevated αSMA expression correlated with cells originating from specimens isolated from biopsies containing more terminal hair follicles; however, αSMA expression was lost upon m-SKP formation. Others have shown that dissociated human hair follicle dermal papilla (DP) are a highly enriched source of SKPs. However, conversely and unexpectedly, monolayer cultured human hair follicle DP cells failed to form m-SKPs whereas those from the murine vibrissae follicles did. Collectively, these findings reveal the potential for using expanded DF cultures to produce SKPs, the heterogeneity of SKP forming potential of skin from distinct anatomical locations and ages, and question the progenitor status of human hair follicle DP cells.

Nuclear damages and oxidative stress: new perspectives for laminopathies

Mutations in genes encoding nuclear envelope proteins, particularly LMNA encoding the A-type lamins, cause a broad range of diverse diseases, referred to as laminopathies. The astonishing variety of diseased phenotypes suggests that different mechanisms could be involved in the pathogenesis of laminopathies. In this review we will focus mainly on two of these pathogenic mechanisms: the nuclear damages affecting the chromatin organization, and the oxidative stress causing un-repairable DNA damages. Alteration in the nuclear profile and in chromatin organization, which are particularly impressive in systemic laminopathies whose cells undergo premature senescence, are mainly due to accumulation of unprocessed prelamin A. The toxic effect of these molecular species, which interfere with chromatin-associated proteins, transcription factors, and signaling pathways, could be reduced by drugs which reduce their farnesylation and/or stability. In particular, inhibitors of farnesyl transferase (FTIs), have been proved to be active in rescuing the altered cellular phenotype, and statins, also in association with other drugs, have been included into pilot clinical trials. The identification of a mechanism that accounts for accumulation of un-repairable DNA damage due to reactive oxygen species (ROS) generation in laminopathic cells, similar to that found in other muscular dystrophies (MDs) caused by altered expression of extracellular matrix (ECM) components, suggests that anti-oxidant therapeutic strategies might prove beneficial to laminopathic patients.

Oxydative stress alters nuclear shape through lamins dysregulation: a route to senescence

Progeroid phenotypes are mainly encountered in 2 types of syndromes: in laminopathies, which are characterized by nuclear shape abnormalities due to lamin A alteration, and in DNA damage response defect syndromes. Because lamin A dysregulation leads to DNA damages, it has been proposed that senescence occurs in both types of syndromes through the accumulation of damages. We recently showed that elevated oxidative stress is responsible for lamin B1 accumulation, nuclear shape alteration and senescence in the DDR syndrome, ataxia telangiectasia (A-T). Interestingly, overexpression of lamin B1 in wild type cells is sufficient to induce senescence without the induction of DNA damages. Here, we will discuss the importance of controlling the lamins level in order for maintenance nuclear architecture and we will comment the relationships of lamins with other senescence mechanisms. Finally, we will describe emerging data reporting redox control by lamins, leading us to propose a general mechanism by which reactive oxygen species can induce senescence through lamin dysregulation and NSA.

Nuclear lamin functions and disease

Recent studies have shown that premature cellular senescence and normal organ development and function depend on the type V intermediate filament proteins, the lamins, which are major structural proteins of the nucleus. This review presents an up-to-date summary of the literature describing new findings on lamin functions in various cellular processes and emphasizes the relationship between the lamins and devastating diseases ranging from premature aging to cancer. Recent insights into the structure and function of the A- and B- type lamins in normal cells and their dysfunctions in diseased cells are providing novel targets for the development of new diagnostic procedures and disease intervention. We summarize these recent findings, focusing on data from mice and humans, and highlight the expanding knowledge of these proteins in both healthy and diseased cells.

Altered chromatin organization and SUN2 localization in mandibuloacral dysplasia are rescued by drug treatment

Mandibuloacral dysplasia type A (MADA) is a rare laminopathy characterized by growth retardation, craniofacial anomalies, bone resorption at specific sites including clavicles, phalanges and mandibula, mottled cutaneous pigmentation, skin rigidity, partial lipodystrophy, and insulin resistance. The disorder is caused by recessive mutations of the LMNA gene encoding for A-type lamins. The molecular feature of MADA consists in the accumulation of the unprocessed lamin A precursor, which is detected at the nuclear rim and in intranuclear aggregates. Here, we report the characterization of prelamin A post-translational modifications in MADA cells that induce alterations in the chromatin arrangement and dislocation of nuclear envelope-associated proteins involved in correct nucleo-cytoskeleton relationships. We show that protein post-translational modifications change depending on the passage number, suggesting the onset of a feedback mechanism. Moreover, we show that treatment of MADA cells with the farnesyltransferase inhibitors is effective in the recovery of the chromatin phenotype, altered in MADA, provided that the cells are at low passage number, while at high passage number, the treatment results ineffective. Moreover, the distribution of the lamin A interaction partner SUN2, a constituent of the nuclear envelope, is altered by MADA mutations, as argued by the formation of a highly disorganized lattice. Treatment with statins partially rescues proper SUN2 organization, indicating that its alteration is caused by farnesylated prelamin A accumulation. Given the major role of SUN1 and SUN2 in the nucleo-cytoskeleton interactions and in regulation of nuclear positioning in differentiating cells, we hypothesise that mechanisms regulating nuclear membrane-centrosome interplay and nuclear movement may be affected in MADA fibroblasts.

Lamins as mediators of oxidative stress

The nuclear lamina defines both structural and functional properties of the eukaryotic cell nucleus. Mutations in the LMNA gene, encoding A-type lamins, lead to a broad spectrum of diseases termed laminopathies. While different hypotheses have been postulated to explain disease development, there is still no unified view on the mechanistic basis of laminopathies. Recent observations indicate that laminopathies are often accompanied by altered levels of reactive oxygen species and a higher susceptibility to oxidative stress at the cellular level. In this review, we highlight the role of reactive oxygen species for cell function and disease development in the context of laminopathies and present a framework of non-exclusive mechanisms to explain the reciprocal interactions between a dysfunctional lamina and altered redox homeostasis.

Gating neural development and aging via nuclear pores

Emerging evidence suggests an involvement of nuclear pore components in the regulation of neural differentiation and aging. These findings will have far-ranging impacts on the understanding of the function of the nuclear envelope in physiological settings and in various neurological diseases.

Automated image analysis of nuclear shape: what can we learn from a prematurely aged cell?

The premature aging disorder, Hutchinson-Gilford progeria syndrome (HGPS), is caused by mutant lamin A, which affects the nuclear scaffolding. The phenotypic hallmark of HGPS is nuclear blebbing. Interestingly, similar nuclear blebbing has also been observed in aged cells from healthy individuals. Recent work has shown that treatment with rapamycin, an inhibitor of the mTOR pathway, reduced nuclear blebbing in HGPS fibroblasts. However, the extent of blebbing varies considerably within each cell population, which makes manual blind counting challenging and subjective. Here, we show a novel, automated and high throughput nuclear shape analysis that quantitatively measures curvature, area, perimeter, eccentricity and additional metrics of nuclear morphology for large populations of cells. We examined HGPS fibroblast cells treated with rapamycin and RAD001 (an analog to rapamycin). Our analysis shows that treatment with RAD001 and rapamycin reduces nuclear blebbing, consistent with blind counting controls. In addition, we find that rapamycin treatment reduces the area of the nucleus, but leaves the eccentricity unchanged. Our nuclear shape analysis provides an unbiased, multidimensional "fingerprint" for a population of cells, which can be used to quantify treatment efficacy and analyze cellular aging.

The role of DNA damage in laminopathy progeroid syndromes

Progeroid laminopathies are characterized by the abnormal processing of lamin A, the appearance of misshapen nuclei, and the accumulation and persistence of DNA damage. In the present article, I consider the contribution of defective DNA damage pathways to the pathology of progeroid laminopathies. Defects in DNA repair pathways appear to be caused by a combination of factors. These include abnormal epigenetic modifications of chromatin that are required to recruit DNA repair pathways to sites of DNA damage, abnormal recruitment of DNA excision repair proteins to sites of DNA double-strand breaks, and unrepairable ROS (reactive oxygen species)-induced DNA damage. At least two of these defective processes offer the potential for novel therapeutic approaches.

Progeria Research Day at Brunel University

Hutchinson-Gilford Progeria Syndrome (HGPS) is a severe premature aging syndrome that affects children. These children display characteristics associated with normal aging and die young usually from cardiovascular problems or stroke. Classical HGPS is caused by mutations in the gene encoding the nuclear structural protein lamin A. This mutation leads to a novel version of lamin A that retains a farnesyl group from its processing. This protein is called Progerin and is toxic to cellular function. Pre-lamin A is an immature version of lamin A and also has a farnesylation modification, which is cleaved in the maturation process to create lamin A.