Human mutations affecting aging--a review

Photoaging protective effects of BIOGF1K, a compound-K-rich fraction prepared from Panax ginseng

BACKGROUND

BIOGF1K, a compound-K-rich fraction, has been shown to display anti-inflammatory activity. Although Panax ginseng is widely used for the prevention of photoaging events induced by UVB irradiation, the effect of BIOGF1K on photoaging has not yet been examined. In this study, we investigated the effects of BIOGF1K on UVB-induced photoaging events.

METHODS

We analyzed the ability of BIOGF1K to prevent UVB-induced apoptosis, enhance matrix metalloproteinase (MMP) expression, upregulate anti-inflammatory activity, reduce sirtuin 1 expression, and melanin production using reverse transcription-polymerase chain reaction, melanin content assay, tyrosinase assay, and flow cytometry. We also evaluated the effects of BIOGF1K on the activator protein-1 signaling pathway, which plays an important role in photoaging, by immunoblot analysis and luciferase reporter gene assays.

RESULTS

Treatment of UVB-irradiated NIH3T3 fibroblasts with BIOGF1K prevented UVB-induced cell death, inhibited apoptosis, suppressed morphological changes, reduced melanin secretion, restored the levels of type I procollagen and sirtuin 1, and prevented mRNA upregulation of MMP-1, MMP-2, and cyclo-oxygenase-2; these effects all occurred in a dose-dependent manner. In addition, BIOGF1K markedly reduced activator-protein-1-mediated luciferase activity and decreased the activity of mitogen-activated protein kinases (extracellular response kinase, p38, and C-Jun N-terminal kinase).

CONCLUSION

Our results strongly suggest that BIOGF1K has anti-photoaging activity and that BIOGF1K could be used in anti-aging cosmeceutical preparations.

Hutchinson-Gilford Progeria Syndrome: A Premature Aging Disease

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

Hutchinson - Gilford progeria syndrome: A rare case report

Hutchinson – Gilford Progeria Syndrome is a rare genetic disorder characterized by premature aging involving the skin, bones, heart, and blood vessels. We report a three-year-old boy with clinical manifestations characteristic of this syndrome. He had a characteristic “plucked-bird” appearance, prominent eyes and scalp veins, senile look, loss of scalp hair, eyebrows, and eyelashes, stunted growth, and mottled pigmentation with sclerodermatous changes over the trunk and lower limbs. Radiological changes and decreased high-density lipoprotein (HDL) levels were also characteristic of the syndrome. This interesting case is reported for its rarity.

The first long-lived mutants: discovery of the insulin/IGF-1 pathway for ageing

Inhibiting insulin/IGF-1 signalling extends lifespan and delays age-related disease in species throughout the animal kingdom. This life-extension pathway, the first to be defined, was discovered through genetic studies in the small roundworm Caenorhabditis elegans. This discovery is described here.

Detection of HLA antigens on progeria syndrome fibroblasts

It has been suggested that cultured skin fibroblasts derived from patients with progeria, a premature aging syndrome, have absent or markedly reduced HLA antigen expression, thus implicating a possible immunological role in the pathogenesis of this disease. An analysis of HLA expression in nine progeric fibroblast strains and related familial strains is reported. Normal HLA expression and inheritance were found. No significant association between HLA type and progeria was detected. Therefore, we conclude an abnormality of HLA expression is unlikely to be an underlying defect in progeria.

Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare genetic disorder that causes premature, rapid aging shortly after birth. Recently, de novo point mutations in the Lmna gene have been found in individuals with HGPS. Lmna encodes lamin A and C, the A-type lamins, which are an important structural component of the nuclear envelope. The most common HGPS mutation is located at codon 608 (G608G). This mutation creates a cryptic splice site within exon 11, which deletes a proteolytic cleavage site within the expressed mutant lamin A. Incomplete processing of prelamin A results in nuclear lamina abnormalities that can be observed in immunofluorescent studies of HGPS cells. Mouse models, such as Lmna knockout, Zmpste24 knockout, and Lmna L530P knockin will help the study of progeria. Lmna mutations have also recently been found in patients with atypical forms of progeria. The discovery of the HGPS mutations brings the total number of diseases caused by mutant Lmna to nine, underscoring the astonishing spectrum of laminopathies. Future research into HGPS could also provide important clues about the general process of aging and aging-related diseases.

Nuclear envelope, nuclear lamina, and inherited disease

The nuclear envelope is composed of the nuclear membranes, nuclear lamina, and nuclear pore complexes. In recent years, mutations in nuclear-envelope proteins have been shown to cause a surprisingly wide array of inherited diseases. While the mutant proteins are generally expressed in most or all differentiated somatic cells, many mutations cause fairly tissue-specific disorders. Perhaps the most dramatic case is that of mutations in A-type lamins, intermediate filament proteins associated with the inner nuclear membrane. Different mutations in the same lamin proteins have been shown to cause striated muscle diseases, partial lipodystrophy syndromes, a peripheral neuropathy, and disorders with features of severe premature aging. In this review, we summarize fundamental aspects of nuclear envelope structure and function, the inherited diseases caused by mutations in lamins and other nuclear envelope proteins, and possible pathogenic mechanisms.

Increased Expression of the Huntingtin Interacting Protein-1 Gene in Cells From Hutchinson Gilford Syndrome (Progeria) Patients and Aged Donors

Hutchinson Gilford syndrome (progeria [PG]) is a human disease associated with accelerated aging. To elucidate the acceleration mechanism, we first tried to transform a PG-derived cell line by infection of a recombinant adenovirus expressing HPV (human papilloma virus)-E6 and HPV-E7 genes. The transfected PG cells had a greater number of population doublings (PD) (>80), faster doubling time, and less staining of senescence-associated ss-galactosidase than the nontransfected PG cells. The transfected cells also showed markedly more detectable telomerase activity than the nontransformed cells. The expression levels of the genes in the E6-transduced and E7-transduced cell line were then compared with those of the nontransfected cell line using an mRNA differential display method, following reverse-transcriptase polymerase chain reaction analysis. Expression of huntingtin interacting protein-1 (HIP-1) gene was found to be increased not only in PG cells but also in fibroblast cells from aged healthy donors. Thus, HIP-1 might be a molecular assistant in the pathogenesis of the cellular senescent process in the human cells tested.

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.

A unifying hypothesis of Alzheimer's disease. IV. Causation and sequence of events

Contrary to common concepts, the brain in Alzheimer's disease (AD) does not follow a suicide but a rescue program. Widely shared features of metabolism in starvation, hibernation and various conditions of energy deprivation, e.g. ischemia, allow the definition of a deprivation syndrome which is a phylogenetically conserved adaptive response to energetic stress. It is characterized by hypometabolism, oxidative stress and adjustments of the glucose-fatty acid cycle. Cumulative evidence suggests that the brain in aging and AD actively adapts to the progressive fuel deprivation. The counterregulatory mechanisms aim to preserve glucose for anabolic needs and promote the oxidative utilization of ketone bodies. The agent mediating the metabolic switch is soluble Abeta which inhibits glucose utilization and stimulates ketone body utilization at various levels. These processes, which are initiated during normal aging, include inhibition of pro-glycolytic neurohormones, cholinergic transmission, and pyruvate dehydrogenase, the key transmitter and effector systems regulating glucose metabolism. Hormonal and effector systems which promote ketone body utilization, such as glucocorticosteroid and galanin activity, GABAergic transmission, nitric oxide, lipid transport, Ca2+ elevation, and ketone body metabolizing enzymes, are enhanced. A multitude of risk factors feed into this pathophysiological cascade at a variety of levels. Taking into account its pleiotropic regulatory actions in the deprivation response, a new name for Abeta is suggested: deprivin. On the other hand, cumulative evidence, taken together compelling, suggests that senile plaques are the dump rather than the driving force of AD. Moreover, the neurotoxic action of fibrillar Abeta is a likely in vitro artifact but does not contribute significantly to the in vivo pathophysiological events. This archaic program, conserved from bacteria to man, aims to ensure the survival of a deprived organism and controls such divergent processes as sporulation, hibernation, aging and aging-related diseases. In contrast to the immature brain, ketone body utilization of the aged brain is no longer sufficient to meet the energetic demands and is later supplemented by lactate, thus recapitulating in reverse order the sequential fuel utilization of the immature brain. The transduction pathways which operate to switch metabolism also convey the programming and balancing of the de-/redifferentiation/apoptosis cell cycle decisions. This encompasses the reiteration of developmental processes such as transcription factor activation, tau hyperphosphorylation, and establishment of growth factor independence by means of Ca2+ set point shift. Thus, the increasing energetic insufficiency results in the progressive centralization of metabolic activity to the neuronal soma, leading to pruning of the axonal/dendritic trees, loss of neuronal polarity, downregulation of neuronal plasticity and, eventually, depending on the Ca2+ -energy-redox homeostasis, degeneration of vulnerable neurons. Finally, it is outlined that genetic (e.g. Down's syndrome, APP and presenilin mutations and apoE4) and environmental risk factors represent progeroid factors which accelerate the aging process and precipitate the manifestation of AD as a progeroid systemic disease. Aging and AD are related to each other by threshold phenomena, corresponding to stage 2, the stage of resistance, and stage 3, exhaustion, of a metabolic stress response.

Characteristics of dynamic mutation in Japanese myotonic dystrophy

To study the characteristics, if any, of unstable CTG repeat sequence in Japanese myotonic dystrophy (DM), we analyzed DNA from 351 at risk individuals (including affected and non-affected carriers and their descendants) from 105 families in Japan. A total of 93 DM families (196 affected and 116 unaffected individuals), including 84 DM parent-child pairs (44 father-child and 40 mother-child pairs), were examined, many of which had been previously tested by linkage analysis. We detected unstable CTG repeat mutations between 0.15 kb and 8.7 kb in size. The size of the mutation correlated with the age of onset of symptoms. There was a significant difference in DM allele size among the four groups (congenital, juvenile onset, classical, and minimal). Congenital DM had on average the largest repeat sizes. Comparison of parent-child pairs showed that most offspring had a larger repeat size than their parents, with only 2 of 84 showing a definite decrease in repeat size. The correlation coefficients for maternal and paternal transmission were 0.41 and 0.15, respectively. The parental age (maternal and paternal) did not correlate with intergenerational change of repeat. These observations are similar to those reported in Caucasians.

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.

The cultured diploid fibroblast as a model for the study of cellular aging

The limited proliferative potential of the cultured human diploid fibroblast is now well established. A number of biological correlates suggest that this culture system is a model for the study of aging at the cellular level. The mechanism(s) that causes the loss of proliferative activity is unknown; the results of some recent studies indicate that specific genes may play a pivotal role in cellular aging in vitro. The extent to which changes in proliferative functions are causally related to aging in vivo is currently under investigation.

Hutchinson-Gilford progeria syndrome: report of a Libyan family and evidence of autosomal recessive inheritance

A Libyan family with the Hutchinson-Gilford progeria syndrome affecting three children of two sisters is described. The proband was ascertained because of repeated unhealing fractures. The pattern of inheritance appeared autosomal recessive.

Evidence for autosomal recessive inheritance of progeria (Hutchinson Gilford)

We have studied a boy with progeria (Hutchinson Gilford) born to third cousins. Four other individuals with progeria were born in another consanguineous sibship in the same family. Thus, this disorder can be inherited as an autosomal recessive trait.

Correlation of DNA repair synthesis with ageing in mice, evidenced by quantitative autoradiography

Fibroblasts from C57B1/6 female mice of different age have been treated with short-wave ultraviolet light. The amount of unscheduled DNA synthesis in the fibroblasts, determined by quantitative histoautoradiography, decreases with the donor's age. This result is discussed with regard to an increase in nuclear area and modifications of cell population dynamics with age. Moreover, differences between individuals of the same age group with regards to unscheduled DNA synthesis have been observed.

The natural history of Huntington disease: possible role of "aging genes"

In this paper we consider a model in which genetic factors that control aging also modify expression of the Huntington disease (HD) gene. Significant correlation coefficients were obtained for age-at-onset (AO) and age-at-death (AD) between affected parents and their affected offspring. However, more relevant to our hypothesis, the correlations between mean AD in normal sibs and AD in the affected parent (r = .57) and mean AD in their affected sibs (r = .54) are also significant. When onset is used instead of death for affected individuals the coefficients are .46 and .52, respectively. Also, AD in the normal parent is significantly correlated with AD in his affected (r = .39) and normal (r = .36) offspring. Current genetic theories on aging and related trends in HD are discussed. Our results and evidence from gerontological studies support the hypothesis that HD gene carriers with "superior" aging genes manifest symptoms later in life and have increased longevity over those with "inferior" aging genes.

Current concepts: II. Hormonal regulation of molecular events during aging

This review is an attempt to establish a role for both glucocorticoid and thyroid hormones in the aging process as factors which mediate the regulation of transcription and translation of specific genetic domains. Furthermore, through a review of the current knowledge of the effect of long-term hypophysectomy on physiological and biochemical functions which change with age in the rat an attempt has been made to establish a role for a pituitary factor in the regulation of the aging process through an affect on transcription and translation of hormonally induced genetic domains. Although we can propose a possible mechanism of action of this factor, the proposal is premature and requires extensive systematic testing. It will be interesting to carefully consider the possible relationship, if any, of this pituitary factor to the effects of dietary restriction on animal longevity. How this pituitary-aging interaction might be exploited is open to speculation but it is certainly worth further consideration based on evidence currently at hand.

Werner's syndrome: a review of recent research with an analysis of connective tissue metabolism, growth control of cultured cells, and chromosomal aberrations

Werner's syndrome is a rare, autosomal recessive condition with multiple progeroid features, but it is an imitation of aging rather than accelerated or premature senescence. Somatic chromosome aberrations occur in multiple tissues in vivo and in vitro, and there is an increased incidence of neoplasia. Thus. Werner's syndrome can be classified in the group of chromosome instability syndromes. Recent findings provide additional support for the concept that there is an aberration of connective tissue metabolism in Werner's syndrome, but it is unclear whether this is a primary or secondary manifestation of the underlying genetic defect. Abnormal growth characteristics are observed in cultured skin fibroblast-like cells and this provides another avenue for current research. Identification of the basic genetic defect in Werner's syndrome might clarify our understanding of the normal aging process in general, or might elucidate specific aspects such as the development of neoplasia, atherosclerosis, diabetes, or osteoporosis.

On the immortality of the germ line: genetic and biochemical mechanism. A review

The nature of the differences between mortal somatic cells and immortal germ cell lines constitutes a major area of theoretical gerontology which has not yet received adequate attention. Weismann's theory, first stated almost exactly a century ago, was recently reconsidered by Kirkwood and Holliday. They applied modern concepts and findings on the factors regulating the accuracy of synthesis of macromolecules to explain germ line immortality. In the present paper, evidence on ageing of reproductive cells and the relationship of cytomorphogenetic events to periodic rejuvenation of germ cell lines is summarized and evaluated. Key events include the elimination or reversal of some DNA changes in germ cells through recombination and meiotic haploidization, cyclic regeneration of transcriptional and translational systems during gametogenesis and early development, and the selection of stable, viable genomes at various stages of the reproductive cycle. These rejuvenatory processes are compared and related to molecular events which differentiated somatic cells are unable to carry out.