The Experts below are selected from a list of 1143 Experts worldwide ranked by ideXlab platform
Kan Cao - One of the best experts on this subject based on the ideXlab platform.
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comparing lamin proteins post translational relative stability using a 2a peptide based system reveals elevated resistance of Progerin to cellular degradation
Nucleus, 2016Co-Authors: Phillip A. Yates, Haoyue Zhang, Kan CaoAbstract:Nuclear lamins are the major components of the nuclear lamina at the periphery of the nucleus, supporting the nuclear envelope and participating in many nuclear processes, including DNA replication, transcription and chromatin organization. A group of diseases, the laminopathies, is associated with mutations in lamin genes. One of the most striking cases is Hutchinson-Gilford progeria syndrome (HGPS) which is the consequence of a lamin A dominant negative mutant named Progerin. Due to the abnormal presence of a permanent C-terminal farnesyl tail, Progerin gradually accumulates on the nuclear membrane, perturbing a diversity of signalings and transcriptional events. The accumulation of Progerin has led to the speculation that Progerin possesses higher stability than the wild type lamin A protein. However, the low solubility of lamin proteins renders traditional immunoprecipitation-dependent methods such as pulse-chase analysis ineffective for comparing the relative stabilities of mutant and wild type lamins. Here, we employ a novel platform for inferring differences in lamin stability, which is based on normalization to a co-translated reporter protein following porcine teschovirus-1 2A peptide-mediated co-translational cleavage. The results obtained using this method support the notion that Progerin is more stable than lamin A. Moreover, treatment of FTI reduces Progerin relative stability to the level of wild type lamin A.
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Comparing lamin proteins post-translational relative stability using a 2A peptide-based system reveals elevated resistance of Progerin to cellular degradation
Nucleus, 2016Co-Authors: Phillip A. Yates, Haoyue Zhang, Kan CaoAbstract:ABSTRACTNuclear lamins are the major components of the nuclear lamina at the periphery of the nucleus, supporting the nuclear envelope and participating in many nuclear processes, including DNA replication, transcription and chromatin organization. A group of diseases, the laminopathies, is associated with mutations in lamin genes. One of the most striking cases is Hutchinson-Gilford progeria syndrome (HGPS) which is the consequence of a lamin A dominant negative mutant named Progerin. Due to the abnormal presence of a permanent C-terminal farnesyl tail, Progerin gradually accumulates on the nuclear membrane, perturbing a diversity of signalings and transcriptional events. The accumulation of Progerin has led to the speculation that Progerin possesses higher stability than the wild type lamin A protein. However, the low solubility of lamin proteins renders traditional immunoprecipitation-dependent methods such as pulse-chase analysis ineffective for comparing the relative stabilities of mutant and wild ty...
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mechanisms controlling the smooth muscle cell death in progeria via down regulation of poly adp ribose polymerase 1
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Haoyue Zhang, Zhengmei Xiong, Kan CaoAbstract:Hutchinson–Gilford progeria syndrome (HGPS) is a severe human premature aging disorder caused by a lamin A mutant named Progerin. Death occurs at a mean age of 13 y from cardiovascular problems. Previous studies revealed loss of vascular smooth muscle cells (SMCs) in the media of large arteries in a patient with HGPS and two mouse models, suggesting a causal connection between the SMC loss and cardiovascular malfunction. However, the mechanisms of how Progerin leads to massive SMC loss are unknown. In this study, using SMCs differentiated from HGPS induced pluripotent stem cells, we show that HGPS SMCs exhibit a profound proliferative defect, which is primarily caused by caspase-independent cell death. Importantly, Progerin accumulation stimulates a powerful suppression of PARP1 and consequently triggers an activation of the error-prone nonhomologous end joining response. As a result, most HGPS SMCs exhibit prolonged mitosis and die of mitotic catastrophe. This study demonstrates a critical role of PARP1 in mediating SMC loss in patients with HGPS and elucidates a molecular pathway underlying the progressive SMC loss in progeria.
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Nuclear localization signal deletion mutants of lamin A and Progerin reveal insights into lamin A processing and emerin targeting
Nucleus, 2014Co-Authors: Andrew R. Flannery, Helen Cai, Kan CaoAbstract:Lamin A is a major component of the lamina, which creates a dynamic network underneath the nuclear envelope. Mutations in the lamin A gene (LMNA) cause severe genetic disorders, one of which is Hutchinson-Gilford progeria syndrome (HGPS), a disease triggered by a dominant mutant named Progerin. Unlike the wild-type lamin A, whose farnesylated C-terminus is excised during post-translational processing, Progerin retains its farnesyl tail and accumulates on the nuclear membrane, resulting in abnormal nuclear morphology during interphase. In addition, membrane-associated Progerin forms visible cytoplasmic aggregates in mitosis. To examine the potential effects of cytoplasmic Progerin, nuclear localization signal (NLS) deleted Progerin and lamin A (PGΔNLS and LAΔNLS, respectively) have been constructed. We find that both ΔNLS mutants are farnesylated in the cytosol and associate with a sub-domain of the ER via their farnesyl tails. While the farnesylation on LAΔNLS can be gradually removed, which leads to its subsequent release from the ER into the cytoplasm, PGΔNLS remains permanently farnesylated and membrane-bounded. Moreover, both ΔNLS mutants dominantly affect emerin’s nuclear localization. These results reveal new insights into lamin A biogenesis and lamin A-emerin interaction.
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Rapamycin Reverses Cellular Phenotypes and Enhances Mutant Protein Clearance in Hutchinson-Gilford Progeria Syndrome Cells
Science Translational Medicine, 2011Co-Authors: Kan Cao, Cecilia D. Blair, Michael R. Erdos, John J. Graziotto, Joseph R. Mazzulli, Dimitri Krainc, Francis S. CollinsAbstract:Hutchinson-Gilford progeria syndrome (HGPS) is a lethal genetic disorder characterized by premature aging. HGPS is most commonly caused by a de novo single-nucleotide substitution in the lamin A/C gene (LMNA) that partially activates a cryptic splice donor site in exon 11, producing an abnormal lamin A protein termed Progerin. Accumulation of Progerin in dividing cells adversely affects the integrity of the nuclear scaffold and leads to nuclear blebbing in cultured cells. Progerin is also produced in normal cells, increasing in abundance as senescence approaches. Here, we report the effect of rapamycin, a macrolide antibiotic that has been implicated in slowing cellular and organismal aging, on the cellular phenotypes of HGPS fibroblasts. Treatment with rapamycin abolished nuclear blebbing, delayed the onset of cellular senescence, and enhanced the degradation of Progerin in HGPS cells. Rapamycin also decreased the formation of insoluble Progerin aggregates and induced clearance through autophagic mechanisms in normal fibroblasts. Our findings suggest an additional mechanism for the beneficial effects of rapamycin on longevity and encourage the hypothesis that rapamycin treatment could provide clinical benefit for children with HGPS.
Karima Djabali - One of the best experts on this subject based on the ideXlab platform.
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Sulforaphane enhances Progerin clearance in Hutchinson–Gilford progeria fibroblasts
2016Co-Authors: Diana Gabriel, Leslie B. Gordon, Daniela Roedl, Karima DjabaliAbstract:Hutchinson–Gilford progeria syndrome (HGPS, OMIM 176670) is a rare multisystem childhood premature aging disorder linked to mutations in the LMNA gene. The most common HGPS mutation is found at position G608G within exon 11 of the LMNA gene. This mutation results in the deletion of 50 amino acids at the carboxyl-terminal tail of prelamin A, and the truncated protein is called Progerin. Progerin only undergoes a subset of the normal post-translational modifications and remains permanently farn-esylated. Several attempts to rescue the normal cellular pheno-type with farnesyltransferase inhibitors (FTIs) and other compounds have resulted in partial cellular recovery. Using proteomics, we report here that Progerin induces changes in the composition of the HGPS nuclear proteome, including alter-ations to several components of the protein degradation path-ways. Consequently, proteasome activity and autophagy are impaired in HGPS cells. To restore protein clearance in HGPS cells, we treated HGPS cultures with sulforaphane (SFN), an antioxi-dant derived from cruciferous vegetables. We determined that SFN stimulates proteasome activity and autophagy in normal and HGPS fibroblast cultures. Specifically, SFN enhances Progerin clearance by autophagy and reverses the phenotypic changes that are the hallmarks of HGPS. Therefore, SFN is a promising therapeutic avenue for children with HGPS. Key words: lamins; progeria; Progerin; proteostasis; senes-cence; sulforaphane
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Progerin impairs chromosome maintenance by depleting cenp f from metaphase kinetochores in hutchinson gilford progeria fibroblasts
Oncotarget, 2016Co-Authors: Veronika Eisch, Xiang Lu, Diana Gabriel, Karima DjabaliAbstract:// Veronika Eisch 1 , Xiang Lu 1 , Diana Gabriel 1 , Karima Djabali 1 1 Epigenetics of Aging, Department of Dermatology, TUM School of Medicine, Technical University Munich (TUM), Garching-Munich, Germany Correspondence to: Karima Djabali, e-mail: djabali@tum.de Keywords: Progerin, lamin, mitosis, CENP-F, Hutchinson-Gilford progeria Received: October 27, 2015 Accepted: March 04, 2016 Published: March 22, 2016 ABSTRACT Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare premature aging disorder that leads to death at an average age of 14.7 years due to myocardial infarction or stroke. The most common mutation in HGPS is at position G608G (GGC>GGT) within exon 11 of the LMNA gene. This mutation results in the deletion of 50 amino acids at the carboxyl-terminal tail of prelamin A, producing a truncated farnesylated protein called Progerin. Lamins play important roles in the organization and structure of the nucleus. The nuclear build-up of Progerin causes severe morphological and functional changes in interphase HGPS cells. In this study, we investigated whether Progerin elicits spatiotemporal deviations in mitotic processes in HGPS fibroblasts. We analyzed the nuclear distribution of endogenous Progerin during mitosis in relation to components of the nuclear lamina, nuclear envelope (NE) and nuclear pores. We found that Progerin caused defects in chromosome segregation as early as metaphase, delayed NE reformation and trapped lamina components and inner NE proteins in the endoplasmic reticulum at the end of mitosis. Progerin displaced the centromere protein F (CENP-F) from metaphase chromosome kinetochores, which caused increased chromatin lagging, binucleated cells and genomic instability. This accumulation of Progerin-dependent defects with each round of mitosis predisposes cells to premature senescence.
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epidermal expression of the truncated prelamin a causing hutchinson gilford progeria syndrome effects on keratinocytes hair and skin
Human Molecular Genetics, 2008Co-Authors: Yuexia Wang, Karima Djabali, Colin L. Stewart, David M Owens, A Panteleyev, Howard J. WormanAbstract:Hutchinson–Gilford progeria syndrome (HGPS) is an accelerated aging disorder caused by point mutation in LMNA encoding A-type nuclear lamins. The mutations in LMNA activate a cryptic splice donor site, resulting in expression of a truncated, prenylated prelamin A called Progerin. Expression of Progerin leads to alterations in nuclear morphology, which may underlie pathology in HGPS. We generated transgenic mice expressing Progerin in epidermis under control of a keratin 14 promoter. The mice had severe abnormalities in morphology of skin keratinocyte nuclei, including nuclear envelope lobulation and decreased nuclear circularity not present in transgenic mice expressing wild-type human lamin A. Primary keratinocytes isolated from these mice had a higher frequency of nuclei with abnormal shape compared to those from transgenic mice expressing wild-type human lamin A. Treatment with a farnesyltransferase inhibitor significantly improved nuclear shape abnormalities and induced the formation of intranuclear foci in the primary keratinocytes expressing Progerin. Similarly, spontaneous immortalization of Progerin-expressing cultured keratinocytes selected for cells with normal nuclear morphology. Despite morphological alterations in keratinocyte nuclei, mice expressing Progerin in epidermis had normal hair grown and wound healing. Hair and skin thickness were normal even after crossing to Lmna null mice to reduce or eliminate expression of normal A-type lamins. Although Progerin induces significant alterations in keratinocyte nuclear morphology that are reversed by inhibition of farnesyltransferasae, epidermal expression does not lead to alopecia or other skin abnormalities typically seen in human subjects with HGPS.
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the mutant form of lamin a that causes hutchinson gilford progeria is a biomarker of cellular aging in human skin
PLOS ONE, 2007Co-Authors: Dayle Mcclintock, Leslie B. Gordon, Francis S. Collins, Desiree Ratner, Meepa Lokuge, David M Owens, Karima DjabaliAbstract:Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare disorder characterized by accelerated aging and early death, frequently from stroke or coronary artery disease. 90% of HGPS cases carry the LMNA G608G (GGC>GGT) mutation within exon 11 of LMNA, activating a splice donor site that results in production of a dominant negative form of lamin A protein, denoted Progerin. Screening 150 skin biopsies from unaffected individuals (newborn to 97 years) showed that a similar splicing event occurs in vivo at a low level in the skin at all ages. While Progerin mRNA remains low, the protein accumulates in the skin with age in a subset of dermal fibroblasts and in a few terminally differentiated keratinocytes. Progerin-positive fibroblasts localize near the basement membrane and in the papillary dermis of young adult skin; however, their numbers increase and their distribution reaches the deep reticular dermis in elderly skin. Our findings demonstrate that Progerin expression is a biomarker of normal cellular aging and may potentially be linked to terminal differentiation and senescence in elderly individuals.
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a lamin a protein isoform overexpressed in hutchinson gilford progeria syndrome interferes with mitosis in progeria and normal cells
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Ka Cao, Michael R. Erdos, Karima Djabali, Ia C Capell, Francis S. CollinsAbstract:Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by dramatic premature aging. Classic HGPS is caused by a de novo point mutation in exon 11 (residue 1824, C → T) of the LMNA gene, activating a cryptic splice donor and resulting in a mutant lamin A (LA) protein termed “Progerin/LAΔ50” that lacks the normal cleavage site to remove a C-terminal farnesyl group. During interphase, irreversibly farnesylated Progerin/LAΔ50 anchors to the nuclear membrane and causes characteristic nuclear blebbing. Progerin/LAΔ50's localization and behavior during mitosis, however, are completely unknown. Here, we report that Progerin/LAΔ50 mislocalizes into insoluble cytoplasmic aggregates and membranes during mitosis and causes abnormal chromosome segregation and binucleation. These phenotypes are largely rescued with either farnesyltransferase inhibitors or a farnesylation-incompetent mutant Progerin/LAΔ50. Furthermore, we demonstrate that small amounts of Progerin/LAΔ50 exist in normal fibroblasts, and a significant percentage of these Progerin/LAΔ50-expressing normal cells are binucleated, implicating Progerin/LAΔ50 as causing similar mitotic defects in the normal aging process. Our findings present evidence of mitotic abnormality in HGPS and may shed light on the general phenomenon of aging.
Francis S. Collins - One of the best experts on this subject based on the ideXlab platform.
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Rapamycin Reverses Cellular Phenotypes and Enhances Mutant Protein Clearance in Hutchinson-Gilford Progeria Syndrome Cells
Science Translational Medicine, 2011Co-Authors: Kan Cao, Cecilia D. Blair, Michael R. Erdos, John J. Graziotto, Joseph R. Mazzulli, Dimitri Krainc, Francis S. CollinsAbstract:Hutchinson-Gilford progeria syndrome (HGPS) is a lethal genetic disorder characterized by premature aging. HGPS is most commonly caused by a de novo single-nucleotide substitution in the lamin A/C gene (LMNA) that partially activates a cryptic splice donor site in exon 11, producing an abnormal lamin A protein termed Progerin. Accumulation of Progerin in dividing cells adversely affects the integrity of the nuclear scaffold and leads to nuclear blebbing in cultured cells. Progerin is also produced in normal cells, increasing in abundance as senescence approaches. Here, we report the effect of rapamycin, a macrolide antibiotic that has been implicated in slowing cellular and organismal aging, on the cellular phenotypes of HGPS fibroblasts. Treatment with rapamycin abolished nuclear blebbing, delayed the onset of cellular senescence, and enhanced the degradation of Progerin in HGPS cells. Rapamycin also decreased the formation of insoluble Progerin aggregates and induced clearance through autophagic mechanisms in normal fibroblasts. Our findings suggest an additional mechanism for the beneficial effects of rapamycin on longevity and encourage the hypothesis that rapamycin treatment could provide clinical benefit for children with HGPS.
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Progerin and telomere dysfunction collaborate to trigger cellular senescence in normal human fibroblasts
Journal of Clinical Investigation, 2011Co-Authors: Kan Cao, Cecilia D. Blair, Dina A. Faddah, Julia E. Kieckhaefer, Michael R. Erdos, Michelle Olive, Elizabeth G. Nabel, Francis S. CollinsAbstract:Hutchinson-Gilford progeria syndrome (HGPS), a devastating premature aging disease, is caused by a point mutation in the lamin A gene (LMNA). This mutation constitutively activates a cryptic splice donor site, resulting in a mutant lamin A protein known as Progerin. Recent studies have demonstrated that Progerin is also produced at low levels in normal human cells and tissues. However, the cause-and-effect relationship between normal aging and Progerin production in normal individuals has not yet been determined. In this study, we have shown in normal human fibroblasts that progressive telomere damage during cellular senescence plays a causative role in activating Progerin production. Progressive telomere damage was also found to lead to extensive changes in alternative splicing in multiple other genes. Interestingly, elevated Progerin production was not seen during cellular senescence that does not entail telomere shortening. Taken together, our results suggest a synergistic relationship between telomere dysfunction and Progerin production during the induction of cell senescence, providing mechanistic insight into how Progerin may participate in the normal aging process.
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the mutant form of lamin a that causes hutchinson gilford progeria is a biomarker of cellular aging in human skin
PLOS ONE, 2007Co-Authors: Dayle Mcclintock, Leslie B. Gordon, Francis S. Collins, Desiree Ratner, Meepa Lokuge, David M Owens, Karima DjabaliAbstract:Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare disorder characterized by accelerated aging and early death, frequently from stroke or coronary artery disease. 90% of HGPS cases carry the LMNA G608G (GGC>GGT) mutation within exon 11 of LMNA, activating a splice donor site that results in production of a dominant negative form of lamin A protein, denoted Progerin. Screening 150 skin biopsies from unaffected individuals (newborn to 97 years) showed that a similar splicing event occurs in vivo at a low level in the skin at all ages. While Progerin mRNA remains low, the protein accumulates in the skin with age in a subset of dermal fibroblasts and in a few terminally differentiated keratinocytes. Progerin-positive fibroblasts localize near the basement membrane and in the papillary dermis of young adult skin; however, their numbers increase and their distribution reaches the deep reticular dermis in elderly skin. Our findings demonstrate that Progerin expression is a biomarker of normal cellular aging and may potentially be linked to terminal differentiation and senescence in elderly individuals.
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a lamin a protein isoform overexpressed in hutchinson gilford progeria syndrome interferes with mitosis in progeria and normal cells
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Ka Cao, Michael R. Erdos, Karima Djabali, Ia C Capell, Francis S. CollinsAbstract:Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by dramatic premature aging. Classic HGPS is caused by a de novo point mutation in exon 11 (residue 1824, C → T) of the LMNA gene, activating a cryptic splice donor and resulting in a mutant lamin A (LA) protein termed “Progerin/LAΔ50” that lacks the normal cleavage site to remove a C-terminal farnesyl group. During interphase, irreversibly farnesylated Progerin/LAΔ50 anchors to the nuclear membrane and causes characteristic nuclear blebbing. Progerin/LAΔ50's localization and behavior during mitosis, however, are completely unknown. Here, we report that Progerin/LAΔ50 mislocalizes into insoluble cytoplasmic aggregates and membranes during mitosis and causes abnormal chromosome segregation and binucleation. These phenotypes are largely rescued with either farnesyltransferase inhibitors or a farnesylation-incompetent mutant Progerin/LAΔ50. Furthermore, we demonstrate that small amounts of Progerin/LAΔ50 exist in normal fibroblasts, and a significant percentage of these Progerin/LAΔ50-expressing normal cells are binucleated, implicating Progerin/LAΔ50 as causing similar mitotic defects in the normal aging process. Our findings present evidence of mitotic abnormality in HGPS and may shed light on the general phenomenon of aging.
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A lamin A protein isoform overexpressed in Hutchinson-Gilford progeria syndrome interferes with mitosis in progeria and normal cells.
Proceedings of the National Academy of Sciences, 2007Co-Authors: Kan Cao, Michael R. Erdos, Karima Djabali, Brian C. Capell, Francis S. CollinsAbstract:Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by dramatic premature aging. Classic HGPS is caused by a de novo point mutation in exon 11 (residue 1824, C --> T) of the LMNA gene, activating a cryptic splice donor and resulting in a mutant lamin A (LA) protein termed "Progerin/LADelta50" that lacks the normal cleavage site to remove a C-terminal farnesyl group. During interphase, irreversibly farnesylated Progerin/LADelta50 anchors to the nuclear membrane and causes characteristic nuclear blebbing. Progerin/LADelta50's localization and behavior during mitosis, however, are completely unknown. Here, we report that Progerin/LADelta50 mislocalizes into insoluble cytoplasmic aggregates and membranes during mitosis and causes abnormal chromosome segregation and binucleation. These phenotypes are largely rescued with either farnesyltransferase inhibitors or a farnesylation-incompetent mutant Progerin/LADelta50. Furthermore, we demonstrate that small amounts of Progerin/LADelta50 exist in normal fibroblasts, and a significant percentage of these Progerin/LADelta50-expressing normal cells are binucleated, implicating Progerin/LADelta50 as causing similar mitotic defects in the normal aging process. Our findings present evidence of mitotic abnormality in HGPS and may shed light on the general phenomenon of aging.
Carlos Lopezotin - One of the best experts on this subject based on the ideXlab platform.
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Progerin accelerates atherosclerosis by inducing endoplasmic reticulum stress in vascular smooth muscle cells
Embo Molecular Medicine, 2019Co-Authors: Tom Misteli, Magda R Hamczyk, Ricardo Villabellosta, Victor Quesada, Pilar Gonzalo, Sandra Vidak, Rosa M Nevado, Maria J Andresmanzano, Carlos LopezotinAbstract: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.
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identification of mitochondrial dysfunction in hutchinson gilford progeria syndrome through use of stable isotope labeling with amino acids in cell culture
Journal of Proteomics, 2013Co-Authors: Jose Riveratorres, Fernando G. Osorio, Carlos Lopezotin, Rebeca Acinperez, Pablo Cabezassanchez, Cristina Gonzalezgomez, Diego Megias, Carmen Camara, Jose Antonio Enriquez, Jose L LuquegarciaAbstract:Abstract 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.
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defective extracellular pyrophosphate metabolism promotes vascular calcification in a mouse model of hutchinson gilford progeria syndrome that is ameliorated on pyrophosphate treatment
Circulation, 2013Co-Authors: Ricardo Villabellosta, Fernando G. Osorio, Carlos Lopezotin, Jose Riveratorres, Rebeca Acinperez, Jose Antonio Enriquez, Vicente AndrésAbstract: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 LmnaG609G/+ mice expressing Progerin, which mimic the main clinical manifestations of HGPS. LmnaG609G/+ 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, Lm...
Tom Misteli - One of the best experts on this subject based on the ideXlab platform.
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systematic screening identifies therapeutic antisense oligonucleotides for hutchinson gilford progeria syndrome
Nature Medicine, 2021Co-Authors: Madaiah Puttaraju, Leslie B. Gordon, Michaela Jackson, Stephanie Klein, Asaf Shilo, Frank C Bennett, Frank Rigo, Tom MisteliAbstract:Hutchinson-Gilford progeria syndrome (HGPS) is a rare, invariably fatal childhood premature aging disorder caused by a pre-messenger RNA (mRNA) splicing defect in the LMNA gene. We used combined in vitro screening and in vivo validation to systematically explore the effects of target sequence, backbone chemistry and mechanism of action to identify optimized antisense oligonucleotides (ASOs) for therapeutic use in HGPS. In a library of 198 ASOs, the most potent ASOs targeted the LMNA exon 12 junction and acted via non-RNase H-mediated mechanisms. Treatment with an optimized lead candidate resulted in extension of lifespan in a mouse model of HGPS. Progerin mRNA levels were robustly reduced in vivo, but the extent of Progerin protein reduction differed between tissues, suggesting a long half-life and tissue-specific turnover of Progerin in vivo. These results identify a novel therapeutic agent for HGPS and provide insight into the HGPS disease mechanism.
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Progerin accelerates atherosclerosis by inducing endoplasmic reticulum stress in vascular smooth muscle cells
Embo Molecular Medicine, 2019Co-Authors: Tom Misteli, Magda R Hamczyk, Ricardo Villabellosta, Victor Quesada, Pilar Gonzalo, Sandra Vidak, Rosa M Nevado, Maria J Andresmanzano, Carlos LopezotinAbstract: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.
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repression of the antioxidant nrf2 pathway in premature aging
Cell, 2016Co-Authors: Nard Kubben, Weiqi Zhang, Guanghui Liu, Lixia Wang, Ty C Voss, Jiping Yang, Tom MisteliAbstract:Hutchinson-Gilford progeria syndrome (HGPS) is a rare, invariably fatal premature aging disorder. The disease is caused by constitutive production of Progerin, a mutant form of the nuclear architectural protein lamin A, leading, through unknown mechanisms, to diverse morphological, epigenetic, and genomic damage and to mesenchymal stem cell (MSC) attrition in vivo. Using a high-throughput siRNA screen, we identify the NRF2 antioxidant pathway as a driver mechanism in HGPS. Progerin sequesters NRF2 and thereby causes its subnuclear mislocalization, resulting in impaired NRF2 transcriptional activity and consequently increased chronic oxidative stress. Suppressed NRF2 activity or increased oxidative stress is sufficient to recapitulate HGPS aging defects, whereas reactivation of NRF2 activity in HGPS patient cells reverses Progerin-associated nuclear aging defects and restores in vivo viability of MSCs in an animal model. These findings identify repression of the NRF2-mediated antioxidative response as a key contributor to the premature aging phenotype.
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a high content imaging based screening pipeline for the systematic identification of anti progeroid compounds
Methods, 2016Co-Authors: Nard Kubben, Kyle R Brimacombe, Megan Donegan, Tom MisteliAbstract:Hutchinson-Gilford Progeria Syndrome (HGPS) is an early onset lethal premature aging disorder caused by constitutive production of Progerin, a mutant form of the nuclear architectural protein lamin A. The presence of Progerin causes extensive morphological, epigenetic and DNA damage related nuclear defects that ultimately disrupt tissue and organismal functions. Hypothesis-driven approaches focused on HGPS affected pathways have been used in attempts to identify druggable targets with anti-progeroid effects. Here, we report an unbiased discovery approach to HGPS by implementation of a high-throughput, high-content imaging based screening method that enables systematic identification of small molecules that prevent the formation of multiple Progerin-induced aging defects. Screening a library of 2816 FDA approved drugs, we identified retinoids as a novel class of compounds that reverses aging defects in HGPS patient skin fibroblasts. These findings establish a novel approach to anti-progeroid drug discovery.
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Lamin A-dependent misregulation of adult stem cells associated with accelerated ageing.
Nat Cell Biol, 2008Co-Authors: Tom MisteliAbstract:The premature-ageing disease Hutchinson-Gilford Progeria Syndrome (HGPS) is caused by constitutive production of Progerin, a mutant form of the nuclear architectural protein lamin A. Progerin is also expressed sporadically in wild-type cells and has been linked to physiological ageing. Cells from HGPS patients exhibit extensive nuclear defects, including abnormal chromatin structure and increased DNA damage. At the organismal level, HGPS affects several tissues, particularly those of mesenchymal origin. How the cellular defects of HGPS cells lead to the organismal defects has been unclear. Here, we provide evidence that Progerin interferes with the function of human mesenchymal stem cells (hMSCs). We find that expression of Progerin activates major downstream effectors of the Notch signalling pathway. Induction of Progerin in hMSCs changes their molecular identity and differentiation potential. Our results support a model in which accelerated ageing in HGPS patients, and possibly also physiological ageing, is the result of adult stem cell dysfunction and progressive deterioration of tissue functions.
