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Ageing is a complex biological process characterized by the progressive loss of biological fitness due to the accumulation of macromolecular and cellular damage that affects most living organisms. Moreover, ageing is an important risk factor for many pathologies, including cardiovascular diseases, neurological disorders, and cancer. However, the ageing rate can be modulated by genetic, nutritional, and pharmacological factors, highlighting the concept of "ageing plasticity". Progeroid syndromes are a group of rare genetic diseases that resemble many characteristics of physiological ageing. Accordingly, studies on these diseases have been very useful for gaining mechanistic insights in ageing biology. In recent years, a great effort has been made in ageing research and several works have confirmed that geromiRs, the growing subgroup of miRNAs implicated in ageing, are able to modulate organismal lifespan. However, very little is still known about the impact of miRNA in premature ageing. In this review, we will address the functional relevance of this class of small non-coding RNAs in the regulation of the hallmarks of progeroid syndromes. In addition, we will discuss the potential strategies for managing progeria based on geromiR modulation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Semantic distinctions between "normal" aging, "pathological" aging (or age-related disease) and "premature" aging (otherwise known as segmental progeria) potentially confound important insights into the nature of each of the complex processes. Here we review a recent, unexpected discovery: the presence of longevity-associated characteristics typical of long-lived endocrine-mutant and dietary-restricted animals in short-lived progeroid mice. These data suggest that a subset of symptoms observed in premature aging, and possibly normal aging as well, may be indirect manifestations of a beneficial adaptive stress response to endogenous oxidative damage, rather than a detrimental result of the damage itself.

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.

It has been shown that enhanced levels of p53 activity contribute to reduced cancer susceptibility in mice, however longevity is compromised due to the onset of an early-ageing phenotype. The effects of enhanced levels of p53 in these in mice could therefore have implications for human premature ageing disorders. We examined the DNA damage response of p53 and its target p21(WAF1) to UV and ionising radiation in fibroblasts from patients with the premature ageing disorder Hutchinson-Gilford Progeria (HGP). We report a normal p53 response to these DNA damaging agents suggesting that, in this particular human disorder, the premature ageing phenotype does not arise from an enhanced p53 response.

A review of human genetic mutations that affect aging and their potential contribution to help understand normal aging processes is presented. The lifespans of most animal species, including man, have a genetically determined maximum. The lifespan of man appears to have evolved exceedingly rapidly, which suggests that relatively few genes may determine longevity. Analysis of biochemical evolution suggests that the regulation of enzyme levels may underlie most evolutionary changes. There is a wide spectrum of human genetic mutations. Some, such as progeria and Werner's syndrome, produce a phenotype resembling premature aging and may involve genes related to the aging process. Certain human chromosomal abnormalities, such as Down's syndrome, produce an appearance of premature aging and may be due to abnormal gene regulatory mechanisms. Progress in understanding the genetic mechanisms underlying aging is likely to come from elucidation of the molecular defects that result in the premature aging syndromes and from insights gained regarding the regulatory mechanisms governing eukaryotic genetic expression.

There have been numerous investigations of thyroid function during senescence in humans. However, very little information is available on thyroid hormone action at the cell level during senescence. Therefore, we have investigated thyroid hormone induction of cell membrane (Na + K)ATPase during human senescence using three experimental fibroblast cell culture systems: (1) cells from premature aging syndrome, progeria; (2) aging in vitro; and (3) early passage cells from aged patients. In all cases senescence is associated with a dramatic alteration from the normal dose-dependent thyroid hormone induction of (Na + K)ATPase. Senescent cells depleted of thyroid hormones demonstrated an elevated activity of (Na + K)ATPase, while non-senescing cells exhibit the characteristic basal enzyme activities in the hypothyroid state. These results indicate that human senescence is associated with extreme alterations in thyroid hormone regulation of (Na + K)ATPase; and may suggest a more general change in thyroid hormone action at senescence. These changes may be associated with important alterations in cell metabolism and intracellular ionic environment during senescence.