Human longevity and common variations in the LMNA gene: a meta-analysis.

A mutation in the LMNA gene is responsible for the most dramatic form of premature aging, Hutchinson-Gilford progeria syndrome (HGPS). Several recent studies have suggested that protein products of this gene might have a role in normal physiological cellular senescence. To explore further LMNA's possible role in normal aging, we genotyped 16 SNPs over a span of 75.4 kb of the LMNA gene on a sample of long-lived individuals (LLI) (US Caucasians with age ≥ 95 years, N=873) and genetically matched younger controls (N=443). We tested all common nonredundant haplotypes (frequency ≥ 0.05) based on subgroups of these 16 SNPs for association with longevity. The most significant haplotype, based on four SNPs, remained significant after adjustment for multiple testing (OR=1.56, P=2.5 × 10(-5) , multiple-testing-adjusted P=0.0045). To attempt to replicate these results, we genotyped 3619 subjects from four independent samples of LLI and control subjects from (i) the New England Centenarian Study (NECS) (N=738), (ii) the Southern Italian Centenarian Study (SICS) (N=905), (iii) France (N=1103), and (iv) the Einstein Ashkenazi Longevity Study (N= 702). We replicated the association with the most significant haplotype from our initial analysis in the NECS sample (OR=1.60, P=0.0023), but not in the other three samples (P > 0.15). In a meta-analysis combining all five samples, the best haplotype remained significantly associated with longevity after adjustment for multiple testing in the initial and follow-up samples (OR=1.18, P=7.5 × 10(-4) , multiple-testing-adjusted P=0.037). These results suggest that LMNA variants may play a role in human lifespan.

Genetics of aging: implications for drug discovery and development.

Aging is not a passive activity, but an actively regulated metabolic process. Specific genes have been identified that regulate aging, although aging, and consequently longevity, is only partially under genetic influence. It is also possible to increase life span by environmental modification; for example, caloric restriction can increase life span. Because human life span is long, directly studying aging in humans is impractical. Fortunately, significant insights into aging can be achieved by studying short-lived organisms, such as yeast, worms, and fruit flies. Many of the molecular pathways regulating aging in these lower organisms are conserved in mammals and overlap with pathways regulating metabolism. For example, an insulin-growth hormone signaling system has been implicated in regulating aging and longevity in both worms and mammals. Furthermore, the dysregulation of glucose homeostasis is a hallmark of aging in humans. In fact, type 2 diabetes, a disease of glucose homeostasis, can be conceptualized as a form of accelerated aging. Consistent with this, aging and diabetes are both common risk factors for a wide range of diseases. Because aging and diabetes are intimately related at a molecular level, diabetes may be able to provide the link between disease treatment (eg, diabetes) and the prevention of age-related diseases. If specific molecular pathways controlling the rate of aging can be modulated genetically, then perhaps they can be modulated pharmacologically. These insights may ultimately have an important impact on the discovery and development of drugs to both treat and prevent a wide range of diseases.

Ageing and metabolism: drug discovery opportunities.

There has recently been significant progress in our understanding of the mechanisms that regulate ageing, and it has been shown that changes in single genes can dramatically extend lifespan and increase resistance to many diseases. Furthermore, many of these genes belong to evolutionarily conserved pathways that also control energy metabolism. In this review, we describe the shared molecular machinery that regulates ageing and energy metabolism. Although drugs to slow ageing face severe regulatory hurdles, it is likely that an understanding of ageing pathways will help to identify novel drug targets to treat metabolic disorders and other age-related diseases.

Sarcomeric genes involved in reverse remodeling of the heart during left ventricular assist device support.

BACKGROUND: Left ventricular assist devices (LVADs) implanted in patients with severe congestive heart failure (CHF) as a bridge to transplantation have been shown to reverse chamber enlargement, regress cellular hypertrophy, and increase contractility. The purpose of this study was to gain a better understanding of the molecular changes associated with increased contractility after LVAD support. METHODS: We took tissue sections from the left ventricular apex of 12 patients with CHF who were undergoing LVAD insertion (pre-LVAD) and from the LV free wall of those same patients before transplantation (post-LVAD). To control for sample-site differences, we obtained samples from the same regions in 7 patients with CHF who were undergoing transplantation without LVAD support and in 4 non- failing donor hearts. Gene expression was then probed on a custom DNA array containing 2,700 cardiac-enriched cDNA clones. RESULTS: Calcium-handling genes were up-regulated by LVAD support, as previously reported. Sarcomeric genes were the other principle class of genes up-regulated by LVAD support, consistent with a possible restoration of sarcomere structure in reverse ventricular remodeling. However, a decrease in the fibrous component of the myocardium, also potentially involved in reverse remodeling, was not evident at the level of gene transcription because fibroblast markers were either unchanged or up-regulated. The remaining regulated genes did not fall into any defined functional class. CONCLUSIONS: Changes in the regulation of sarcomeric, calcium-handling, and fibroblast genes during LVAD support indicate a cardiac molecular adaptation to mechanical unloading. These molecular changes may play a role in the observed increase in contractile function during reverse remodeling.

Haplotype-based identification of a microsomal transfer protein marker associated with the human lifespan.

We previously reported a genomewide linkage study for human longevity using 308 long-lived individuals (LLI) (centenarians or near-centenarians) in 137 sibships and identified statistically significant linkage within chromosome 4 near microsatellite D4S1564. This interval spans 12 million bp and contains approximately 50 putative genes. To identify the specific gene and gene variants impacting lifespan, we performed a haplotype-based fine-mapping study of the interval. The resulting genetic association study identified a haplotype marker within microsomal transfer protein as a modifier of human lifespan. This same variant was tested in a second cohort of LLI from France, and although the association was not replicated, there was evidence for statistical distortion in the form of Hardy-Weinberg disequilibrium. Microsomal transfer protein has been identified as the rate-limiting step in lipoprotein synthesis and may affect longevity by subtly modulating this pathway. This study provides proof of concept for the feasibility of using the genomes of LLI to identify genes impacting longevity.