It is well established that age-related decline of the biological capacity of a woman to reproduce is primarily related to the poor developmental potential of her gametes. This renders female ageing the most significant determinant of success in IVF. Starting with a reference picture of the main molecular and cellular failures of aged oocytes, granulosa cells and follicular microenvironment, this review focuses on age-related biochemical mechanisms underlying these changes. According to the most relevant concept of ageing, age-associated malfuction results from physiological accumulation of irreparable damage to biomolecules as an unavoidable side effect of normal metabolism. More than a decade after the free radical theory of ovarian ageing, biological and clinical research supporting the involvement of oxidative injuries in follicle ageing is discussed. Looking for the aetiology of oxidative stress, we consider the effect of ageing on ovarian and follicular vascularization. Then, we propose a potential role of advanced glycation end-products known to be involved in the physiological ageing of most tissues and organs. We conclude that future investigation of age-related molecular damage in the different ovarian components will be imperative in order to evaluate the possibility to save or rescue the developmental potential of aged oocytes.

The p53 transcription factor plays a critical role in cellular responses to stress. Its activation in response to DNA damage leads to cell growth arrest, allowing for DNA repair, or directs cellular senescence or apoptosis, thereby maintaining genome integrity. Senescence is a permanent cell-cycle arrest that has a crucial role in aging, and it also represents a robust physiological antitumor response, which counteracts oncogenic insults. In addition, senescent cells can also negatively impact the surrounding tissue microenvironment and the neighboring cells by secreting pro-inflammatory cytokines, ultimately triggering tissue dysfunction and/or unfavorable outcomes. This review focuses on the characteristics of senescence and on the recent advances in the contribution of p53 to cellular senescence. Moreover, we also discuss the p53-mediated regulation of several pathophysiological microenvironments that could be associated with senescence and its development.Biomolecules 2020, 10, 420 2 of 16 focus on the p53-dependent senescence signaling pathways involved with different stages of senescence and with a consideration for the associated key biomarkers. We also provide an overview on the regulation of p53-mediated cellular senescence in the context of different pathophysiological conditions. Senescence as Cellular Response to StressCellular senescence is defined as a cell state characterized by prolonged and generally irreversible cell-cycle arrest [14] and the acquisition of different phenotypic alterations, including morphological changes, chromatin remodeling, metabolic reprogramming, and secretion of pro-inflammatory factors or SASP (senescence associated secretory phenotypes). These latter count cytokines, growth factors, proteases, and non-soluble extracellular matrix proteins [15]. All these features ultimately limit the replication of both old and damaged cells. Upon physiological conditions, proliferating cells commit to a regular cell cycle [15,16]. On the other hand, both physiological aging, characterized by telomere shortening, and long-term chronic stress, which impairs genomic integrity and stability, could lead to the activation of the senescence pathway [17]. In this sense, the senescence can be viewed as an adaptative response of cells and organisms when exposed to certain unfavorable environmental conditions.Stressors include both intrinsic factors, such as oxidative damage, telomere attrition, hyperproliferation, oncogene activation, and environmental sources, including UV-light, γ-irradiation, and chemotherapeutic drugs [18,19]. Regardless of their origin, the stress factors trigger DNA damage responses (DDR) in the affected cells, which can result in different outcomes, depending on the cell type and the extent of the damage [20]. Mild DNA damage normally induces cell cycle arrest, while severe injury can activate the senescence program or the death programs; the latter includes apoptosis, mitotic catastrophe, autophagy, and necrosis [21].p53 plays a pivotal role in determining the fate of th...

The work was supported by the Ministero dell'Università e della Ricerca Scientifica (MIUR) to C.T., F.A., C.D., A.M.D. The authors declare no conflict of interest.

The aim of this work was to study the antioxidant enzymatic defences in human follicular fluid and investigate their possible changes during reproductive ageing. To this end, we tested the specific activities and protein expression of enzymes involved in reactive oxygen species (ROS) scavenging and in detoxification of ROS byproducts in follicular fluid from young (range 27-32 years, n = 12) and older (range 39-45 years, n = 12) women participating in an IVF programme. Results show that all the tested enzymes [superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione transferase, glutathione reductase] were significantly expressed in human follicular fluid. However, when the two age groups were compared, we found that follicular fluid from older women exhibited a reduced level of glutathione transferase and catalase activities and a higher level of SOD activity. Immunoblot analysis revealed that ageing was associated with decreased protein expression of GST Pi isoform and did not affect SOD and catalase protein expression. Taken together, these findings indicate that reproductive ageing is accompanied by a change in the antioxidant enzymatic pattern that could impair ROS scavenging efficiency in the follicular environment.

The present review provides challenges and opportunities to stimulate research and exploit Sirtuin-based signalling as diagnostic tools and potential targets for therapeutic applications in reproductive medicine.

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Limited knowledge exists about changes in follicle quality associated with age. The aim of this work was to investigate whether ageing may cause oxidative stress-mediated alterations in human granulosa cells (GCs) from periovulatory follicles. GCs employed in this study were obtained from follicular aspirates of 20 younger women (range 27-32 years) and 20 older women (range 38-41 years) undergoing an IVF treatment. Results obtained from comparative RT-PCR analysis revealed that the mean relative levels of mRNAs coding for superoxide dismutases, Cu, ZnSOD (SOD1), MnSOD (SOD2) and catalase were significantly decreased in women ³38 years (P < 0.05, Student's t-test). These changes were associated with a reduced expression of SOD1, SOD2 and catalase at the protein level. When examined at an ultrastructural level, most of the GCs from this group showed defective mitochondria and fewer lipid droplets than those observed in the younger group. These results indicate that GCs from older patients suffer from age-dependent oxidative stress injury and are taken as an evidence for reduced defence against reactive oxygen species (ROS) in GCs during reproductive ageing.

In search for strategies aimed at preventing oxidative threat to female fertility, a possible role of sirtuins has emerged. Sirtuins (silent information regulator 2 (Sir2) proteins), NAD+ dependent enzymes with deacetylase and/or mono-ADP-ribosyltransferase activity, are emerging as key antiaging molecules and regulators in many diseases. Recently, a crucial role for SIRT1 and SIRT3, the main components of sirtuin family, as sensors and guardians of the redox state in oocytes, granulosa cells, and early embryos has emerged. In this context, the aim of the present review is to summarize current knowledge from research papers on the role of sirtuins in female fertility with particular emphasis on the impairment of SIRT1 signalling with oocyte aging. On this basis, the authors wish to build up a framework to promote research on the possible role of sirtuins as targets for future strategies for female fertility preservation.