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Correction of cellular phenotypes of Hutchinson-Gilford Progeria cells by RNA interference.

The great majority of cases of the Hutchinson-Gilford progeroid syndrome (HGPS) ("Progeria of Childhood'') are caused by a single nucleotide mutation (1824 C->T) in the LMNA gene which encodes lamin A and C, nuclear intermediate filaments that are important components of the nuclear lamina. The resultant mutant protein (Delta50 lamin A) is thought to act in a dominant fashion. We exploited RNA interference technology to suppress Delta50 lamin A expression, with the long range goal of intervening in the pathogenesis of the coronary artery atherosclerosis that typically leads to the death of HGPS patients. Short hairpin RNA (shRNA) constructs were designed to target the mutated pre-spliced or mature LMNA mRNAs, and were expressed in HGPS fibroblasts carrying the 1824 C->T mutations using lentiviruses. One of the shRNAs targeted to the mutated mRNA reduced the expression levels of Delta50 lamin A to 26% or lower. The reduced expression was associated with amelioration of abnormal nuclear morphology, improvement of proliferative potential, and reduction in the numbers of senescent cells. These findings provide a rationale for potential gene therapy.

Cell Culture Techniques↗

LMNA is mutated in Hutchinson-Gilford progeria (MIM 176670) but not in Wiedemann-Rautenstrauch progeroid syndrome (MIM 264090).

Hutchinson-Gilford progeria syndrome (HGPS; MIM 176670) is an extremely rare disease that is characterized by accelerated aging and early death, frequently from coronary artery disease. Wiedemann-Rautenstrauch syndrome (WRS; MIM 264090) is another extremely rare disease that is characterized by progeroid features from birth with multiple somatic anomalies and paucity of subcutaneous fat. Because mutations in LMNA, encoding nuclear lamin A/C, cause other lipodystrophy syndromes, we sequenced LMNA (MIM 150330) from the genomic DNAs of seven unrelated HGPS probands and two unrelated WRS probands. We found four novel LMNA coding sequence variants among the HGPS probands, namely R471C, R527C, G608S and c.2036C>T. All seven HGPS probands had at least one LMNA variant, which were found in none of the genomes of 100 normal subjects ( P<4 x 10(-11)). In contrast, neither of the WRS proband genomes had any LMNA sequence abnormality. The strong association of rare LMNA coding sequence mutations with HGPS implicates this syndrome as a laminopathy, while WRS is most probably due to mutations in another gene.

Adolescent↗

Ankyrin G overexpression in Hutchinson-Gilford progeria syndrome fibroblasts identified through biological filtering of expression profiles.

Hutchinson-Gilford progeria syndrome (HGPS; MIM 176670) is a rare disease characterized by accelerated aging. In this study, light and immunofluorescence microscopy were used to assess morphological changes, measures of cell growth kinetics and gene expression profiles in HGPS cells and normal fibroblasts in culture. A filtering strategy was developed based on differentially expressed transcripts seen consistently across three culture stages based on cell passage number. This filtering strategy produced a list of 66 unique differentially expressed genes, of which approximately 40% were upregulated in HGPS cells compared to normal fibroblasts. The increased mRNA expression in HGPS cells that was seen for one gene defined using this strategy--namely ANK3--was validated using quantitative reverse-transcriptase amplification, Western analysis and immunofluorescence microscopy, all of which showed significantly increased ankyrin G expression. These findings demonstrate differences in morphology, growth kinetics and mRNA expression profiles in HGPS cells compared to normal fibroblasts in culture, including increased expression of ANK3/ankyrin G. Furthermore, other genes that co-clustered with ANK3 might provide mechanistic clues regarding senescence in cultured HGPS cells.

Ankyrins↗

Hutchinson-Gilford progeria syndrome in a 45-year-old man.

A 45-year-old man with typical Hutchinson-Gilford progeria syndrome is described. The patient had the characteristic physical findings of this syndrome, such as short stature, "horse-riding" stance, coxa valga, alopecia, micrognathia, craniofacial disproportion, and prominent eyes. He had refractory congestive heart failure due to arteriosclerotic heart disease and hypertension, and he also had arteriosclerosis obliterans. Some immunologic and endocrinologic abnormalities commonly seen in the elderly were present in this patient. On the basis of a review of the literature, this is the first patient with this syndrome who had survived into the fourth decade.

Arteriosclerosis Obliterans↗

Cell culture studies in progeria. I. Establishment and partial characterization of a lymphoblastoid cell line.

A lymphoblastoid cell line (EKS-L44) with definitive HLA specificities (HLA-Aw24, w30, B14, w35, Cw4-, DRw4, 5) was established from peripheral blood cells of a patient with progeria using Epstein-Barr virus. Cytogenetic study indicated that EKS-L44 was diploid after four months in vitro. The growth pattern of this cell line was not significantly different from a similarly established normal control nor from other lines initiated from patients with various disorders.

Cell Line↗

Familial co-segregation of the elastin phenotype in skin fibroblasts from Hutchinson-Gilford progeria.

Elastin and type IV collagen production are markedly elevated in fibroblasts derived from the skin of patients with Hutchinson-Gilford progeria (HGP). Fibroblasts from three affected children and their parents were compared to normal human skin fibroblasts with respect to elastin production as a function of different concentrations of calf serum and the cytokines, transforming growth factor-beta and basic fibroblast growth factor (TGF-beta 1, bFGF). In cultured fibroblasts from the parents of probands that were very high elastin producers (> 10(5) molecular equivalents/cell per h), at least one parent (mother) presented the same phenotype. Overproduction of elastin in culture could have been due to increased sensitivity of HGP strains to stimuli present in serum; however, relative stimulation of elastin production by calf serum in cell strains from HGP elastin over-producers was less than half the control strain. In most of the cultures examined, the responsiveness of elastin production to TGF-beta 1 was almost absent when compared to the response of normal fibroblasts. HGP strains with high elastin production modified conditioned medium to enhance elastin production in normal cells. These results suggest the presence, in HGP skin fibroblasts, of inheritance of high elastin production that is associated with accelerated aging.

Adolescent↗

Impaired proliferation response after PDGF induction in fibroblasts from Hutchinson-Guilford Progeria syndrome.

Fibroblasts from a Hutchinson-Guilford Progeria Syndrome (HGPS) patient were compared to normal human fibroblasts to determine if differences existed in growth factor mediated cell proliferation. Cultures of progeric fibroblasts were exposed individually to platelet-derived growth factor (PDGF), epidermal growth factor (EGF), platelet poor plasma (PPP) and fetal bovine serum (FBS). Autoradiographic studies using 3H thymidine showed that progeric fibroblasts had similar labeling indices relative to controls after exposure to FBS and EGF. In contrast, progeric cells made competent with PDGF and later treated with 5% PPP had a significantly lower labeling index. This and preliminary observations on fos RNA accumulation suggests the possible existence of a genetic defect in HGPS fibroblasts.

Autoradiography↗

Cell-cycle defect of DNA repair in progeria skin fibroblasts.

We examined the temporal regulation of DNA repair during synchronous cell proliferation in normal and progeroid human fibroblasts. Ultraviolet light-induced (254 nm, 20 J/m2) unscheduled DNA synthesis was measured at 4-h intervals after serum stimulation, for up to 32 h. Normal cells regulated DNA repair in a defined temporal sequence, showing a peak in the induction of DNA repair just before DNA synthesis. Progeroid skin fibroblasts failed to show an increase in nucleotide excision repair before scheduled DNA synthesis, but the background level of DNA repair was not significantly different from that in controls. Regulation of repair in progeroid human fibroblasts appeared similar, but not identical to that previously reported by Gupta and Sirover (1984b) for xeroderma pigmentosum complementation group C. Our results suggest that patients with Hutchinson-Gilford progeria may have a defect in DNA repair; the results offer nominal evidence that the average level of UV-induced DNA is decreased, and that individuals with this disease lack both the normal enhancement of DNA repair before scheduled DNA synthesis and the temporal control of DNA repair.

Cell Cycle↗

Fibroblast clones from patients with Hutchinson-Gilford progeria can senesce despite the presence of telomerase.

Hutchinson-Gilford progeria (HGP) is a genetic disorder in which individuals prematurely display features of ageing. Mutations in LMNA (lamin A) have recently been shown to underlie HGP, although how such mutations lead to the complex phenotype seen in the disease remains unclear. HGP is often associated with the premature replicative senescence of dermal fibroblasts. Normally dermal fibroblast senescence is initiated by erosion of chromosomal ends (telomeres) resulting from sustained cell division. Since ectopic expression of telomerase reproducibly immortalises human dermal fibroblasts, it is of interest to determine whether HGP fibroblasts immortalise via the same route, and at the same frequency. Three strains of HGP fibroblasts (AGO6917A, AGO6297B and AGO8466) were infected with a retroviral vector expressing the catalytic subunit of telomerase (hTERT). Here we report that fibroblast clones derived from HGP donors frequently fail to immortalise with telomerase. Of the 15 independently isolated clones from the three donors, five failed to immortalise despite the restoration of telomerase activity and the stabilisation of telomere length. In contrast, out of four clones isolated from a culture of hTERT transduced control fibroblasts, no failures to immortalise were detected. This suggests a novel cellular phenotype in HGP, one whereby the HGP mutation confers resistance to 'telomerisation'.

Cells, Cultured↗

Reduced adiponectin and HDL cholesterol without elevated C-reactive protein: clues to the biology of premature atherosclerosis in Hutchinson-Gilford Progeria Syndrome.

OBJECTIVES: Children with Hutchinson-Gilford Progeria Syndrome (HGPS) die of severe premature atherosclerosis at an average age of 13 years. Although the LMNA gene defect responsible for this "premature aging syndrome" has been identified, biological mechanisms underlying the accelerated atherosclerosis are unknown. We determined whether children with HGPS demonstrate abnormalities in known biomarkers for cardiovascular disease (CVD) risk. STUDY DESIGN: We quantified serum lipids, lipoproteins, C-reactive protein (CRP), and adiponectin in children with HGPS and age-matched control children. RESULTS: HDL cholesterol (P < .0001) and adiponectin (P < .001) concentrations decreased significantly with increasing age in HGPS but not in control children. There was a positive correlation between these variables in HGPS ( P < .0001) but not control children. Mean total cholesterol, LDL and HDL cholesterol, triglyceride, and median CRP levels were similar between HGPS and control children (all P > .05). CONCLUSIONS: Declining HDL cholesterol and adiponectin with advancing age may contribute to accelerated atherosclerotic plaque formation in HGPS. Several factors frequently associated with CVD risk in normal aging (elevated CRP, total and LDL cholesterol) showed no difference and are unlikely to influence CVD risk in HGPS. HDL and adiponectin may represent significant mediators and potential therapeutic targets for atherosclerosis in HGPS.

Adiponectin↗

A-type nuclear lamins, progerias and other degenerative disorders.

Nuclear lamins were identified as core nuclear matrix constituents over 20 years ago. They have been ascribed structural roles such as maintaining nuclear integrity and assisting in nuclear envelope formation after mitosis, and have also been linked to nuclear activities including DNA replication and transcription. Recently, A-type lamin mutations have been linked to a variety of rare human diseases including muscular dystrophy, lipodystrophy, cardiomyopathy, neuropathy and progeroid syndromes (collectively termed laminopathies). Most diseases arise from dominant, missense mutations, leading to speculation as to how different mutations in the same gene can give rise to such a diverse set of diseases, some of which share little phenotypic overlap. Understanding the cellular dysfunctions that lead to laminopathies will almost certainly provide insight into specific roles of A-type lamins in nuclear organization. Here, we compare and contrast the LMNA mutations leading to laminopathies with emphasis on progerias, and discuss possible functional roles for A-type lamins in the maintenance of healthy tissues.

Aging↗

Aggrecan expression is substantially and abnormally upregulated in Hutchinson-Gilford Progeria Syndrome dermal fibroblasts.

Hutchinson-Gilford Progeria syndrome (HGPS) is a rare genetic disorder that displays features of segmental aging. It is manifested predominantly in connective tissue, with most prominent histological changes occurring in the skin, cartilage, bone and cardiovascular tissues. Detailed quantitative real time reverse-transcription polymerase chain reaction studies confirmed the previous observation that platelet-derived growth factor A-chain transcripts are consistently elevated 11+/-2- to 13+/-2-fold in two HGPS dermal fibroblast lines compared with age-matched controls. Furthermore, we identified two additional genes with substantially altered transcript levels. Nucleotide pyrophosphatase transcription was virtually shut down with decreased expression of 13+/-3- to 59+/-3-fold in HGPS, whereas aggrecan mRNA was elevated to 24+/-5 times to 41+/-4 times that of chronologically age-matched controls. Aggrecan, normally a component of cartilage and not always detectable in normal fibroblasts cultures, was secreted by HGPS fibroblast lines and was produced as a proteoglycan. This demonstrates that elevated aggrecan expression and its secretion are aberrant features of HGPS. We conclude that HGPS cells can display massively altered transcript levels leading to the secretion of inappropriate protein species.

Actins↗

Progeria in siblings.

Progeria or 'prematurely old' is an autosomal recessive trait that appears insidiously at or after the age of 6 months. Two affected siblings are reported showing radiologically progressive attenuation of the clavicles and terminal phalanges, widening of cranial sutures and mandibular hypoplasia. Scleroderma was also present. Out of 59 previously published cases five had scleroderma before the age of 2 years. Only three families with affected siblings have been previously recorded.

Bone Resorption↗

Response to nutritional and growth hormone treatment in progeria.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare condition with an unknown molecular defect. Patients with HGP progressively develop failure to thrive (FTT), alopecia, loss of subcutaneous fat, scleroderma, stiffening of various joints, and severe atherosclerosis. The median life span is 13 years, and the main cause of death is cardiovascular complications. There are few reports of endocrine and metabolic studies because of the rarity of this condition, and the response to long-term growth hormone (GH) treatment has not been described. We report the results of endocrine and metabolic studies performed to investigate the etiology of growth failure in five patients with HGP. Additionally, the response to nutritional therapy (NT) and GH treatment in three of these patients is presented. Our results suggest that elevated GH levels are characteristic of this disease and that an elevated basal metabolic rate (BMR) could be the cause of the FTT seen in HGP. Nonaggressive NT slightly improved weight gain and growth velocity (GV). Combined NT and GH treatment in three patients improved the GV, increased the levels of growth factors, and paradoxically resulted in decreased BMRs. However, the response to these therapies decreased over time and did not seem to prevent the progression of atherosclerotic disease.

Adolescent↗

Recurrent de novo point mutations in lamin A cause Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by features reminiscent of marked premature ageing. Here, we present evidence of mutations in lamin A (LMNA) as the cause of this disorder. The HGPS gene was initially localized to chromosome 1q by observing two cases of uniparental isodisomy of 1q-the inheritance of both copies of this material from one parent-and one case with a 6-megabase paternal interstitial deletion. Sequencing of LMNA, located in this interval and previously implicated in several other heritable disorders, revealed that 18 out of 20 classical cases of HGPS harboured an identical de novo (that is, newly arisen and not inherited) single-base substitution, G608G(GGC > GGT), within exon 11. One additional case was identified with a different substitution within the same codon. Both of these mutations result in activation of a cryptic splice site within exon 11, resulting in production of a protein product that deletes 50 amino acids near the carboxy terminus. Immunofluorescence of HGPS fibroblasts with antibodies directed against lamin A revealed that many cells show visible abnormalities of the nuclear membrane. The discovery of the molecular basis of this disease may shed light on the general phenomenon of human ageing.

Adult↗

Reversal of the cellular phenotype in the premature aging disease Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is a childhood premature aging disease caused by a spontaneous point mutation in lamin A (encoded by LMNA), one of the major architectural elements of the mammalian cell nucleus. The HGPS mutation activates an aberrant cryptic splice site in LMNA pre-mRNA, leading to synthesis of a truncated lamin A protein and concomitant reduction in wild-type lamin A. Fibroblasts from individuals with HGPS have severe morphological abnormalities in nuclear envelope structure. Here we show that the cellular disease phenotype is reversible in cells from individuals with HGPS. Introduction of wild-type lamin A protein does not rescue the cellular disease symptoms. The mutant LMNA mRNA and lamin A protein can be efficiently eliminated by correction of the aberrant splicing event using a modified oligonucleotide targeted to the activated cryptic splice site. Upon splicing correction, HGPS fibroblasts assume normal nuclear morphology, the aberrant nuclear distribution and cellular levels of lamina-associated proteins are rescued, defects in heterochromatin-specific histone modifications are corrected and proper expression of several misregulated genes is reestablished. Our results establish proof of principle for the correction of the premature aging phenotype in individuals with HGPS.

Alternative Splicing↗

Oral and maxillofacial surgical considerations for a case of Hutchinson-Gilford progeria.

Hutchinson-Guilford progeria is a rare genetic condition showing the stigmata of accelerated ageing combined with severe growth retardation. Patients with this condition show a classical facies and clinical features with an average age of death of 13, usually due to atherosclerotic changes. Craniofacial and dental manifestations include mandibular and maxillary hypoplasia, both vertically and horizontally. Delayed and abnormal tooth eruption and morphology are commonly present. The long-term medical prognosis and eruption potential of individual teeth is important when considering treatment. In addition to this, surgical planning and surgical technique must be modified by the abnormal facial morphology, dermal inelasticity, potential anaesthetic difficulties, and ongoing deterioration in the medical condition. These factors mandate early and definitive intervention for oral surgical conditions. We report the case of a 13-year-old male treated for pericoronitis and oral pain relating to delayed eruption of first permanent molars.

Child↗

Accumulation of mutant lamin A causes progressive changes in nuclear architecture in Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder, commonly caused by a point mutation in the lamin A gene that results in a protein lacking 50 aa near the C terminus, denoted LADelta50. Here we show by light and electron microscopy that HGPS is associated with significant changes in nuclear shape, including lobulation of the nuclear envelope, thickening of the nuclear lamina, loss of peripheral heterochromatin, and clustering of nuclear pores. These structural defects worsen as HGPS cells age in culture, and their severity correlates with an apparent increase in LADelta50. Introduction of LADelta50 into normal cells by transfection or protein injection induces the same changes. We hypothesize that these alterations in nuclear structure are due to a concentration-dependent dominant-negative effect of LADelta50, leading to the disruption of lamin-related functions ranging from the maintenance of nuclear shape to regulation of gene expression and DNA replication.

Aged↗