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Hutchinson–Gilford progeria syndrome (HGPS, progeria) is a rare genetic disease characterized by premature aging and death in childhood for which there were no approved drugs for its treatment until last November, when lonafarnib obtained long-sought FDA approval. However, the benefits of lonafarnib in patients are limited, highlighting the need for new therapeutic strategies. Here, we validate the enzyme isoprenylcysteine carboxylmethyltransferase (ICMT) as a new therapeutic target for progeria with the development of a new series of potent inhibitors of this enzyme that exhibit an excellent antiprogeroid profile. Among them, compound UCM-13207 significantly improved the main hallmarks of progeria. Specifically, treatment of fibroblasts from progeroid mice with UCM-13207 delocalized progerin from the nuclear membrane, diminished its total protein levels, resulting in decreased DNA damage, and increased cellular viability. Importantly, these effects were also observed in patient-derived cells. Using the LmnaG609G/G609G progeroid mouse model, UCM-13207 showed an excellent in vivo efficacy by increasing body weight, enhancing grip strength, extending lifespan by 20%, and decreasing tissue senescence in multiple organs. Furthermore, UCM-13207 treatment led to an improvement of key cardiovascular hallmarks such as reduced progerin levels in aortic and endocardial tissue and increased number of vascular smooth muscle cells (VSMCs). The beneficial effects go well beyond the effects induced by other therapeutic strategies previously reported in the field, thus supporting the use of UCM-13207 as a new treatment for progeria., Isoprenylcysteine carboxylmethyltransferase (ICMT) inhibitor induces progerin delocalization from the nuclear rim and decreases its levels, significantly improving the main hallmarks of progeria.

Lamin A, a product of the LMNA gene, is an essential nuclear envelope component in most differentiated cells. Mutations in LMNA have been linked to premature aging disorders, including Hutchinson-Gilford progeria syndrome (HGPS). HGPS is caused by progerin, an aberrant form of lamin A that leads to premature death, typically from the complications of atherosclerotic disease. A key characteristic of HGPS is a severe loss of vascular smooth muscle cells (VSMCs) in the arteries. Various mouse models of HGPS have been created, but few of them feature VSMC depletion and none develops atherosclerosis, the death-causing symptom of the disease in humans. We recently generated a mouse model that recapitulates most features of HGPS, including VSMC loss and accelerated atherosclerosis. Furthermore, by generating cell-type-specific HGPS mouse models, we have demonstrated a central role of VSMC loss in progerin-induced atherosclerosis and premature death. M.R.H. is supported by a ‘Juan de la Cierva’ postdoctoral fellowship (FJCI-2017-33299) from the Spanish Ministerio de Ciencia, Innovación yUniversidades (MCIU). Work in V.A.’s laboratory is supported by grants from the Spanish Instituto de Salud Carlos III (AC16/00091 and AC17/00067) and MCIU (SAF2016-79490-R), with co-funding from the Fondo Europeo de Desarrollo Regional (FEDER, ‘Una manera de hacer Europa’), the Progeria Research Foundation (Established Investigator Award 2014-52), and the Fundació Marató TV3 (122/C/2015). The CNIC is supported by theMCIU and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505); Instituto de Salud Carlos III [AC16/00091 and AC17/00067]; MCIU [SAF2016-79490-R]; MCIU [FJCI2017-33299]; MCIU [SEV-2015-0505]; Progeria Research Foundation [2014-52]. Sí

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease that recapitulates many symptoms of physiological aging and precipitates death. Patients develop severe vascular alterations, mainly massive vascular smooth muscle cell loss, vessel stiffening, calcification, fibrosis, and generalized atherosclerosis, as well as electrical, structural, and functional anomalies in the heart. As a result, most HGPS patients die of myocardial infarction, heart failure, or stroke typically during the first or second decade of life. No cure exists for HGPS, and therefore it is of the utmost importance to define the mechanisms that control disease progression in order to develop new treatments to improve the life quality of patients and extend their lifespan. Since the discovery of the HGPS-causing mutation, several animal models have been generated to study multiple aspects of the syndrome and to analyze the contribution of different cell types to the acquisition of the HGPS-associated cardiovascular phenotype. This review discusses current knowledge about cardiovascular features in HGPS patients and animal models and the molecular and cellular mechanisms through which progerin causes cardiovascular disease. This study was supported by grants to V.A. from the Spanish Ministerio de Ciencia e Innovación (MCIN) (PID2019-108489RB-I00) and the Instituto de Salud Carlos III (ISCIII) (grant AC17/00067, as coordinator of the E-Rare Joint Transnational call 2017 project “TREAT-HGPS,” European Union Horizon 2020 Framework Programme) with co-funding from the European Regional Development Fund (ERDF, “A way to build Europe”), the Progeria Research Foundation (Award PRF 2019–77), and the Fundación Marató TV3 (38/C/2020). I.B. was supported by the Comunidad Autónoma de Madrid (grant 2017-T1/BMD-5247). The CNIC is supported by the MCIN, the ISCIII, and the Pro CNIC Foundation. Sí

Inflammation is a hallmark of aging and accelerated aging syndromes such as Hutchinson–Gilford progeria syndrome (HGPS). In this study, we present evidence of increased expression of the components of the NLRP3 inflammasome pathway in HGPS skin fibroblasts, an outcome that was associated with morphological changes of the nuclei of the cells. Lymphoblasts from HGPS patients also showed increased basal levels of NLRP3 and caspase 1. Consistent with these results, the expression of caspase 1 and Nlrp3, but not of the other inflammasome receptors was higher in the heart and liver of Zmpste24−/− mice, which phenocopy the human disease. These data were further corroborated in LmnaG609G/G609G mice, another HGPS animal model. We also showed that pharmacological inhibition of the NLRP3 inflammasome by its selective inhibitor, MCC950, improved cellular phenotype, significantly extended the lifespan of progeroid animals, and reduced inflammasome‐dependent inflammation. These findings suggest that inhibition of the NLRP3 inflammasome is a potential therapeutic approach for the treatment of HGPS., This study reveals a critical role of the NLRP3‐inflammasome complex in the pathogenesis of Hutchinson‐Gilford Progeria (HGPS). Targeting NLRP3 may be a novel potential therapeutic strategy for progeria treatment.

Progeria is an ultra-rare (prevalence 1 in 20 million), fatal, pediatric autosomal dominant premature aging disease caused by a mutation in the LMNA gene. This mutation results in accumulation of a high level of an aberrant form of the nuclear membrane protein, Lamin A. This aberrant protein, termed progerin, accumulates in many tissues and is responsible for the diverse array of disease phenotypes. Children die predominantly from premature atherosclerotic cardiovascular disease. The Progeria Research Foundation's 10th International Scientific Workshop took place via webinar on November 2 and 3, 2020. Participants from 30 countries joined in this new, virtual meeting format. Patient family presentations led the program, followed by updates on Progeria's first-ever application for FDA drug approval as well as initial results from the only current Progeria clinical trial. This was followed by presentations of unpublished preclinical data on drugs in development targeting the disease-causing DNA mutation, the aberrant mRNA, progerin protein, and its downstream effector proteins. Tying bench to bedside, clinicians presented new discoveries on the natural history of disease to inform future clinical trial development and new Progeria aortic valve replacement procedures. The program engaged the Progeria research community as a single unit with a common goal - to treat and cure children with Progeria worldwide. Sí

Aims Hutchinson–Gilford progeria syndrome (HGPS) is an ultrarare laminopathy caused by expression of progerin, a lamin A variant, also present at low levels in non-HGPS individuals. HGPS patients age and die prematurely, predominantly from cardiovascular complications. Progerin-induced cardiac repolarization defects have been described previously, although the underlying mechanisms are unknown. Methods and results We conducted studies in heart tissue from progerin-expressing LmnaG609G/G609G (G609G) mice, including microscopy, intracellular calcium dynamics, patch-clamping, in vivo magnetic resonance imaging, and electrocardiography. G609G mouse cardiomyocytes showed tubulin-cytoskeleton disorganization, t-tubular system disruption, sarcomere shortening, altered excitation–contraction coupling, and reductions in ventricular thickening and cardiac index. G609G mice exhibited severe bradycardia, and significant alterations of atrio-ventricular conduction and repolarization. Most importantly, 50% of G609G mice had altered heart rate variability, and sinoatrial block, both significant signs of premature cardiac aging. G609G cardiomyocytes had electrophysiological alterations, which resulted in an elevated action potential plateau and early afterdepolarization bursting, reflecting slower sodium current inactivation and long Ca+2 transient duration, which may also help explain the mild QT prolongation in some HGPS patients. Chronic treatment with low-dose paclitaxel ameliorated structural and functional alterations in G609G hearts. Conclusions Our results demonstrate that tubulin-cytoskeleton disorganization in progerin-expressing cardiomyocytes causes structural, cardiac conduction, and excitation–contraction coupling defects, all of which can be partially corrected by chronic treatment with low dose paclitaxel., Graphical Abstract

Aging is the main risk factor for cardiovascular and metabolic diseases, which have become a global concern as the world population ages. These diseases and the aging process are exacerbated in Hutchinson–Gilford progeria syndrome (HGPS or progeria). Here, we evaluated the cardiometabolic disease in animal models of premature and normal aging with the aim of identifying alterations that are shared or specific to each condition. Despite differences in body composition and metabolic markers, prematurely and normally aging mice developed heart failure and similar cardiac electrical abnormalities. High‐throughput proteomics of the hearts of progeric and normally aged mice revealed altered protein oxidation and glycation, as well as dysregulated pathways regulating energy metabolism, proteostasis, gene expression, and cardiac muscle contraction. These results were corroborated in the hearts of progeric pigs, underscoring the translational potential of our findings, which could help in the design of strategies to prevent or slow age‐related cardiometabolic disease., We have evaluated cardiac and metabolic disease in animal models of aging. Despite differences in body composition, progeric and normally aged mice developed heart failure and similar cardiac electrical alterations. High‐throughput proteomics of the hearts of these animals revealed dysregulation of energy metabolism, proteostasis, gene expression, and cardiac contraction pathways. These results were corroborated in progeric pigs, underscoring the translational potential of our findings.

Hutchinson&ndash, Gilford progeria syndrome (HGPS) is among the most devastating of the laminopathies, rare genetic diseases caused by mutations in genes encoding nuclear lamina proteins. HGPS patients age prematurely and die in adolescence, typically of atherosclerosis-associated complications. The mechanisms of HGPS-related atherosclerosis are not fully understood due to the scarcity of patient-derived samples and the availability of only one atheroprone mouse model of the disease. Here, we generated a new atherosusceptible model of HGPS by crossing progeroid LmnaG609G/G609G mice, which carry a disease-causing mutation in the Lmna gene, with Ldlr&minus, /&minus, mice, a commonly used preclinical atherosclerosis model. Ldlr&minus, LmnaG609G/G609G mice aged prematurely and had reduced body weight and survival. Compared with control mice, Ldlr&minus, LmnaG609G/G609G mouse aortas showed a higher atherosclerosis burden and structural abnormalities typical of HGPS patients, including vascular smooth muscle cell depletion in the media, adventitial thickening, and elastin structure alterations. Atheromas of Ldlr&minus, LmnaG609G/G609G mice had features of unstable plaques, including the presence of erythrocytes and iron deposits and reduced smooth muscle cell and collagen content. Ldlr&minus, LmnaG609G/G609G mice faithfully recapitulate vascular features found in patients and thus provide a new tool for studying the mechanisms of HGPS-related atherosclerosis and for testing therapies.

[EN] Ageing is the main risk factor for cardiovascular disease (CVD). The increased prevalence of CVD is partly due to the global increase in life expectancy. In this context, it is essential to identify the mechanisms by which ageing induces CVD, with the ultimate aim of reducing its incidence. Both atherosclerosis and heart failure significantly contribute to age-associated CVD morbidity and mortality. Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder caused by the synthesis of progerin, which is noted for accelerated ageing and CVD. This mutant form of prelamin A induces generalised atherosclerosis, vascular calcification, and cardiac electrophysiological abnormalities, leading to premature ageing and death, mainly due to myocardial infarction and stroke. This review discusses the main vascular structural and functional abnormalities during physiological and premature ageing, as well as the mechanisms involved in the exacerbated CVD and accelerated ageing induced by the accumulation of progerin and prelamin A. Both proteins are expressed in non-HGPS individuals, and physiological ageing shares many features of progeria. Research into HGPS could therefore shed light on novel mechanisms involved in the physiological ageing of the cardiovascular system., [ES] El envejecimiento es el principal factor de riesgo de enfermedad cardiovascular (ECV) y su prevalencia está aumentando progresivamente debido en gran parte al incremento de la esperanza de vida a nivel mundial. En este contexto, es fundamental establecer cuáles son los mecanismos por los que el envejecimiento promueve el desarrollo de ECV, con el objetivo de reducir su incidencia. La aterosclerosis y la insuficiencia cardiaca contribuyen de manera significativa a la morbimortalidad por ECV asociada a la edad. El síndrome de progeria de Hutchinson-Gilford (HGPS) se caracteriza por un envejecimiento prematuro que cursa también con ECV acelerada. Se trata de un trastorno genético raro causado por la expresión de progerina, una forma mutada de la prelamina A. La progerina induce aterosclerosis masiva y alteraciones electrofisiológicas en el corazón, promueve el envejecimiento y finalmente la muerte prematura a una edad media de 14,6 anos, ˜ principalmente por infarto de miocardio o ictus cerebral. En esta revisión se discuten las principales alteraciones estructurales y funcionales que afectan al sistema vascular durante el envejecimiento fisiológico y prematuro, así como los mecanismos que subyacen a la aterosclerosis y al envejecimiento exagerados inducidos por la prelamina A y la progerina. Dado que ambas proteínas se expresan en individuos sin HGPS y muchas de las características del envejecimiento normal se presentan en la progeria, la investigación en el ámbito del HGPS podría contribuir a la identificación de nuevos mecanismos implicados en el envejecimiento cardiovascular fisiológico., The laboratory work carried out by V.A. was funded by the Ministry of Economy, Industry and Competition (MEIC; SAF2016-79490-R) and the Instituto de Salud Carlos III (ISCIII, Spanish public health research institute) (RD12/0042/0028 and AC16/00091), with co-financing from the European Regional Development Fund (ERDF), TV3’s Fundació Marató (122/C/2015) and the Progeria research Foundation (Established Investigator Award 2014-52). The Biomedical Research Network Centres (CIBER) for Cardiovascular Diseases is an ISCIII initiative. L.C. received assistance from the ISCIII Cardiovascular Research Network’s Jordi Soler postdocotral grants programme, and M.R.H. received predoctoral assistance from the MEIC’s FPI (research staff training) programme (BES2011-043938). The CNIC (Spanish national cardiovascular research centre) receives support from the MEIC and the Fundación Pro-CNIC and has been accredited as a ‘‘Severo Ochoa’’ Centre of Excellence (MEIC SEV-2015-0505).

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder caused by progerin, a mutant lamin A variant. HGPS patients display accelerated aging and die prematurely, typically from atherosclerosis complications. Recently, we demonstrated that progerin-driven vascular smooth muscle cell (VSMC) loss accelerates atherosclerosis leading to premature death in apolipoprotein E-deficient mice. However, the molecular mechanism underlying this process remains unknown. Using a transcriptomic approach, we identify here endoplasmic reticulum stress (ER) and the unfolded protein responses as drivers of VSMC death in two mouse models of HGPS exhibiting ubiquitous and VSMC-specific progerin expression. This stress pathway was also activated in HGPS patient-derived cells. Targeting ER stress response with a chemical chaperone delayed medial VSMC loss and inhibited atherosclerosis in both progeria models, and extended lifespan in the VSMC-specific model. Our results identify a mechanism underlying cardiovascular disease in HGPS that could be targeted in patients. Moreover, these findings may help to understand other vascular diseases associated with VSMC death, and provide insight into aging-dependent vascular damage related to accumulation of unprocessed toxic forms of lamin A. Work in VA’s laboratory is supported by grants from the Spanish Instituto de Salud Carlos III (RD12/0042/0028, AC17/00067 and AC16/00091) and Ministerio de Ciencia, Innovación y Universidades (MCIU) (SAF2016-79490-R), with cofunding from the Fondo Europeo de Desarrollo Regional (FEDER, “Una manera de hacer Europa”), the Progeria Research Foundation (Established Investigator Award 2014-52), and the Fundació Marató TV3 (122/C/2015). The CNIC is supported by the MCIU and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505). Work in the Lopez-Otin laboratory is supported by grants from the Ministerio de Economía y Competitividad (MINECO/FEDER), the European Research Council, and the Progeria Research Foundation. The Instituto Universitario de Oncología is supported by Obra Social Cajastur. Work in the Misteli laboratory was supported by the Intramural Research Program of the National Institutes of Health, National Cancer Institute, and Center for Cancer Research. The MCIU supported RVB (“Juan de la Cierva” JCI-2011-09663 and SAF-2014-60699-JIN postdoctoral contracts) and MRH (FPI predoctoral contract BES-2011-043938 and “Juan de la Cierva” FJCI-2017-33299 postdoctoral contract). RMN is supported by the Ministerio de Educación, Cultura y Deporte (FPU predoctoral contract FPU16/05027). VQ is supported by grants from the Principado de Asturias and MINECO, including FEDER funding. SV was supported by an Erwin Schroedinger Fellowship from the Austrian Science Fund (J3849-B28). Sí

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare genetic disorder for which no cure exists. The disease is characterized by premature aging and inevitable death in adolescence due to cardiovascular complications. Most HGPS patients carry a heterozygous de novo LMNA c.1824C > T mutation, which provokes the expression of a dominant-negative mutant protein called progerin. Therapies proven effective in HGPS-like mouse models have yielded only modest benefit in HGPS clinical trials. To overcome the gap between HGPS mouse models and patients, we have generated by CRISPR-Cas9 gene editing the first large animal model for HGPS, a knockin heterozygous LMNA c.1824C > T Yucatan minipig. Like HGPS patients, HGPS minipigs endogenously co-express progerin and normal lamin A/C, and exhibit severe growth retardation, lipodystrophy, skin and bone alterations, cardiovascular disease, and die around puberty. Remarkably, the HGPS minipigs recapitulate critical cardiovascular alterations seen in patients, such as left ventricular diastolic dysfunction, altered cardiac electrical activity, and loss of vascular smooth muscle cells. Our analysis also revealed reduced myocardial perfusion due to microvascular damage and myocardial interstitial fibrosis, previously undescribed readouts potentially useful for monitoring disease progression in patients. The HGPS minipigs provide an appropriate preclinical model in which to test human-size interventional devices and optimize candidate therapies before advancing to clinical trials, thus accelerating the development of effective applications for HGPS patients. This project was mainly supported by an Established Investigator Award from the Progeria Research Foundation (2014-52), and from the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIU), and the European Regional Development Fund (FEDER, “A way to build Europe”) (SAF2016-79490-R, CB16/11/00405). Ana Barettino has a predoctoral contract from MCIU (BES-2017-079705). Work at Universidad de Murcia is supported by Fundación Seneca-Agencia de Ciencia y Tecnología de la Región de Murcia (20040/GERM/16). The CNIC is supported by the MCIU and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505). Sí

Background: Progerin, an aberrant protein that accumulates with age, causes the rare genetic disease Hutchinson-Gilford progeria syndrome (HGPS). Patients who have HGPS exhibit ubiquitous progerin expression, accelerated aging and atherosclerosis, and die in their early teens, mainly of myocardial infarction or stroke. The mechanisms underlying progerin-induced atherosclerosis remain unexplored, in part, because of the lack of appropriate animal models. Methods: We generated an atherosclerosis-prone model of HGPS by crossing apolipoprotein E–deficient ( Apoe –/– ) mice with Lmna G609G/G609G mice ubiquitously expressing progerin. To induce progerin expression specifically in macrophages or vascular smooth muscle cells (VSMCs), we crossed Apoe –/– Lmna LCS/LCS mice with LysMCre and SM22αCre mice, respectively. Progerin expression was evaluated by polymerase chain reaction and immunofluorescence. Cardiovascular alterations were determined by immunofluorescence and histology in male mice fed normal chow or a high-fat diet. In vivo low-density lipoprotein retention was assessed by intravenous injection of fluorescently labeled human low-density lipoprotein. Cardiac electric defects were evaluated by electrocardiography. Results: Apoe –/– Lmna G609G/G609G mice with ubiquitous progerin expression exhibited a premature aging phenotype that included failure to thrive and shortened survival. In addition, high-fat diet–fed Apoe –/– Lmna G609G/G609G mice developed a severe vascular pathology, including medial VSMC loss and lipid retention, adventitial fibrosis, and accelerated atherosclerosis, thus resembling most aspects of cardiovascular disease observed in patients with HGPS. The same vascular alterations were also observed in Apoe –/– Lmna LCS/LCS SM22αCre mice expressing progerin specifically in VSMCs, but not in Apoe –/– Lmna LCS/LCS LysMCre mice with macrophage-specific progerin expression. Moreover, Apoe –/– Lmna LCS/LCS SM22αCre mice had a shortened lifespan despite the lack of any overt aging phenotype. Aortas of ubiquitously and VSMC-specific progerin-expressing mice exhibited increased retention of fluorescently labeled human low-density lipoprotein, and atheromata in both models showed vulnerable plaque features. Immunohistopathological examination indicated that Apoe –/– Lmna LCS/LCS SM22αCre mice, unlike Apoe –/– Lmna G609G/G609G mice, die of atherosclerosis-related causes. Conclusions: We have generated the first mouse model of progerin-induced atherosclerosis acceleration, and demonstrate that restricting progerin expression to VSMCs is sufficient to accelerate atherosclerosis, trigger plaque vulnerability, and reduce lifespan. Our results identify progerin-induced VSMC death as a major factor triggering atherosclerosis and premature death in HGPS.

Aging, the main risk factor for cardiovascular disease (CVD), is becoming progressively more prevalent in our societies. A better understanding of how aging promotes CVD is therefore urgently needed to develop new strategies to reduce disease burden. Atherosclerosis and heart failure contribute significantly to age-associated CVD-related morbimortality. CVD and aging are both accelerated in patients suffering from Hutchinson-Gilford progeria syndrome (HGPS), a rare genetic disorder caused by the prelamin A mutant progerin. Progerin causes extensive atherosclerosis and cardiac electrophysiological alterations that invariably lead to premature aging and death. This review summarizes the main structural and functional alterations to the cardiovascular system during physiological and premature aging and discusses the mechanisms underlying exaggerated CVD and aging induced by prelamin A and progerin. Because both proteins are expressed in normally aging non-HGPS individuals, and most hallmarks of normal aging occur in progeria, research on HGPS can identify mechanisms underlying physiological aging. Progeria Research Foundation (Established Investigator Award 2014-52). L.d.C. is the recipient of a Jordi Soler postdoctoral fellowship from the Red de Investigacion Cardiovascular at ISCIII. The CNIC is supported by the MEIC and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (MEIC award SEV-2015-0505).

Lamin A is a nuclear intermediate filament protein with important structural and regulatory roles in most differentiated mammalian cells. Excessive accumulation of its precursor prelamin A or the mutant form called 'progerin' causes premature aging syndromes. Progeroid 'laminopathies' are characterized by severe cardiovascular problems (cardiac electrical defects, vascular calcification and stiffening, atherosclerosis, myocardial infarction, and stroke) and premature death. Here, we review studies in cell and mouse models and patients that are unraveling how abnormal prelamin A and progerin accumulation accelerates cardiovascular disease and aging. This knowledge is essential for developing effective therapies to treat progeria and may help identify new mechanisms underlying normal aging. Work in the laboratory of V.A. is supported by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO) (SAF2013-46663-R) and the Instituto de Salud Carlos III (RD12/0042/0028) with co-funding from the Fondo Europeo de Desarrollo Regional (FEDER), the Fundacio Marato TV3 (122/C/2015), and the Progeria Research Foundation (Established Investigator Award 2014-52). The CNIC is supported by the MINECO and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505). Sí

UNLABELLED: Hutchinson-Gilford progeria syndrome (HGPS) is a rare segmental premature aging disorder that recapitulates some biological and physical aspects of physiological aging. The disease is caused by a sporadic dominant mutation in the LMNA gene that leads to the expression of progerin, a mutant form of lamin A that lacks 50 amino acids and retains a toxic farnesyl modification in its carboxy-terminus. However, the mechanisms underlying cellular damage and senescence and accelerated aging in HGPS are incompletely understood. Here, we analyzed fibroblasts from healthy subjects and HGPS patients using SILAC (stable isotope labeling with amino acids in cell culture). We found in HGPS cells a marked downregulation of mitochondrial oxidative phosphorylation proteins accompanied by mitochondrial dysfunction, a process thought to provoke broad organ decline during normal aging. We also found mitochondrial dysfunction in fibroblasts from adult progeroid mice expressing progerin (Lmna(G609G/G609G) knock-in mice) or prelamin A (Zmpste24-null mice). Analysis of tissues from these mouse models revealed that the damaging effect of these proteins on mitochondrial function is time- and dose-dependent. Mitochondrial alterations were not observed in the brain, a tissue with extremely low progerin expression that seems to be unaffected in HGPS. Remarkably, mitochondrial function was restored in progeroid mouse fibroblasts treated with the isoprenylation inhibitors FTI-277 or pravastatin plus zoledronate, which are being tested in HGPS clinical trials. Our results suggest that mitochondrial dysfunction contributes to premature organ decline and aging in HGPS. Beyond its effects on progeria, prelamin A and progerin may also contribute to mitochondrial dysfunction and organ damage during normal aging, since these proteins are expressed in cells and tissues from non-HGPS individuals, most prominently at advanced ages. BIOLOGICAL SIGNIFICANCE: Mutations in LMNA or defective processing of prelamin A causes premature aging disorders, including Hutchinson-Gilford progeria syndrome (HGPS). Most HGPS patients carry in heterozygosis a de-novo point mutation (c.1824C>T: GGC>GGT; p.G608G) which causes the expression of the lamin A mutant protein called progerin. Despite the importance of progerin and prelamin A in accelerated aging, the underlying molecular mechanisms remain largely unknown. To tackle this question, we compared the proteome of skin-derived dermal fibroblast from HGPS patients and age-matched controls using quantitative stable isotope labeling with amino acids in cell culture (SILAC). Our results show a pronounced down-regulation of several components of the mitochondrial ATPase complex accompanied by up-regulation of some glycolytic enzymes. Accordingly, functional studies demonstrated mitochondrial dysfunction in HGPS fibroblasts. Moreover, our expression and functional studies using cellular and animal models confirmed that mitochondrial dysfunction is a feature of progeria which develops in a time- and dose-dependent manner. Finally, we demonstrate improved mitochondrial function in progeroid mouse cells treated with a combination of statins and aminobisphosphonates, two drugs that are being evaluated in ongoing HGPS clinical trials. Although further studies are needed to unravel the mechanisms through which progerin and prelamin A provoke mitochondrial abnormalities, our findings may pave the way to improved treatments of HGPS. These studies may also improve our knowledge of the mechanisms leading to mitochondrial dysfunction during normal aging, since both progerin and prelamin A have been found to accumulate during normal aging. Work in the author's laboratories is supported by grants from the Spanish Ministry of Economy and Competiveness (MINECO) (SAF2010-16044; SAF2011-23089, SAF2009-08007, CSD2007-00020, CTQ2010-18644), Instituto de Salud Carlos III (ISCIII) (RD06/0014/ 0021, RD12/0042/0028), the Progeria Research Foundation (Innovator Award PRF 2012-42), and Comunidad de Madrid (S2011/BMD-2402). P.C.-S. was financially supported by an FPU scholarship from the Spanish Ministry of Education. The Centro Nacional de Investigaciones Cardiovasculares (CNIC) is supported by MINECO and Pro-CNIC Foundation, and the Instituto Universitario de Oncología by Obra Social Cajastur. Sí

Background— Progerin is a mutant form of lamin A responsible for Hutchinson-Gilford progeria syndrome (HGPS), a premature aging disorder characterized by excessive atherosclerosis and vascular calcification that leads to premature death, predominantly of myocardial infarction or stroke. The goal of this study was to investigate mechanisms that cause excessive vascular calcification in HGPS. Methods and Results— We performed expression and functional studies in wild-type mice and knock-in Lmna G609G/+ mice expressing progerin, which mimic the main clinical manifestations of HGPS. Lmna G609G/+ mice showed excessive aortic calcification, and primary aortic vascular smooth muscle cells from these progeroid animals had an impaired capacity to inhibit vascular calcification. This defect in progerin-expressing vascular smooth muscle cells is associated with increased expression and activity of tissue-nonspecific alkaline phosphatase and mitochondrial dysfunction, which leads to reduced ATP synthesis. Accordingly, Lmna G609G/+ vascular smooth muscle cells are defective for the production and extracellular accumulation of pyrophosphate, a major inhibitor of vascular calcification. We also found increased alkaline phosphatase activity and reduced ATP and pyrophosphate levels in plasma of Lmna G609G/+ mice without changes in phosphorus and calcium. Treatment with pyrophosphate inhibited vascular calcification in progeroid mice. Conclusions— Excessive vascular calcification in Lmna G609G mice is caused by reduced extracellular accumulation of pyrophosphate that results from increased tissue-nonspecific alkaline phosphatase activity and diminished ATP availability caused by mitochondrial dysfunction in vascular smooth muscle cells. Excessive calcification is ameliorated on pyrophosphate treatment. These findings reveal a previously undefined pathogenic process in HGPS that may also contribute to vascular calcification in normal aging, because progerin progressively accumulates in the vascular tissue of individuals without HGPS.

25 páginas, 6 figuras. Enlaces a 4 figuras y 2 videos desde supporting information, Nuclear lamins are important structural and functional proteins in mammalian cells, but little is known about the mechanisms and cofactors that regulate their traffic into the nucleus. Here, we demonstrate that trafficking of lamin A, but not lamin B1, and its assembly into the nuclear envelope are regulated by sorting nexin 6 (SNX6), a major component of the retromer that targets proteins and other molecules to specific subcellular locations. SNX6 interacts with lamin A in vitro and in vivo and links it to the outer surface of the endoplasmic reticulum in human and mouse cells. SNX6 transports its lamin A cargo to the nuclear envelope in a process that takes several hours. Lamin A protein levels in the nucleus augment or decrease, respectively, upon gain or loss of SNX6 function. We further show that SNX6-dependent lamin A nuclear import occurs across the nuclear pore complex via a RAN-GTP-dependent mechanism. These results identify SNX6 as a key regulator of lamin A synthesis and incorporation into the nuclear envelope., Work in VA's laboratory is supported by the Ministerio de Economía y Competitividad (MINECO) and Fondo Europeo de Desarrollo Regional (FEDER) (SAF2010-16044), Instituto de Salud Carlos III (ISCIII) (RD12/0042/0028), The Progeria Research Foundation, and the European Commission (Grant No 317916-Liphos). JMGG received salary support from the Sara Borrell and Miguel Servet (CP11/00145) ISCIII programs. The Centro Nacional de Investigaciones Cardiovasculares (CNIC) is supported by MINECO and Fundación Pro-CNIC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.