| Name | Umberto |
| Surname | Galderisi |
| Institution | Università degli Studi della Campania Luigi Vanvitelli |
| Telephone | +39 081 566 75 85 |
| umberto.galderisi@unicampania.it | |
| Address | Dept. of Experimental Medicine, Via Luigi De Crecchio 7 – 80138 Napoli, Italy |
Chromatin modifiers play a crucial role in maintaining cell identity through modulation of gene expression patterns. Their deregulation can have profound effects on cell fate and functions. Among epigenetic regulators, the MECP2 protein is particularly attractive. Mutations in the gene are responsible for more than 90% of cases of Rett syndrome (RTT), a progressive neurodevelopmental disorder. As a chromatin modulator, MECP2 can have a key role in the government of stem cell biology. Previously, we showed that deregulated MECP2 expression triggers senescence in mesenchymal stromal cells (MSCs) from (RTT) patients. Over the last few decades, it has emerged that senescent cells show alterations in the metabolic state. Metabolic changes related to stem cell senescence are particularly detrimental, since they contribute to the exhaustion of stem cell compartments, which in turn determine the falling in tissue renewal and functionality. Herein, we dissect the role of impaired MECP2 function in triggering senescence along with other senescence-related aspects, such as metabolism, in MSCs from a mouse model of RTT. We found that MECP2 deficiencies lead to senescence and impaired mitochondrial energy production. Our results support the idea that an alteration in mitochondria metabolic functions could play an important role in the pathogenesis of RTT.
Base excision repair (BER) is a frontline repair mechanism that operates through the G phase of the cell cycle, which ensures the genome integrity by repairing thousands of DNA lesions due to endogenous and exogenous agents. Its correct functioning is fundamental for cell viability and the health of the organism. Uracil is one of the most prevalent lesions that appears in DNA arising by spontaneous or enzymatic deamination of cytosine or misincorporation of the deoxyuridine 5'-triphosphate nucleotide (dUTP) in place of deoxythymidine 5'-triphosphate (dTTP) during DNA replication. In the first pathway, the uracil will preferentially pair with adenine, leading to C:G → T:A transition. When uracil in DNA arises from misincorporation of dUTP instead of dTTP, this process will result in A:U pairs. Organisms counteract the mutagenic effects of uracil in DNA using the BER repair system, which is mediated by a member of the uracil-DNA glycosylase (UDG) superfamily. Several assays evaluating the in vitro BER enzyme activity have been described so far. Some of these measure the BER activity by an oligonucleotide incision assay using radiolabeled duplex oligo. Others use circular double-stranded DNA substrates containing a defined lesion. The novelty of our method resides in its rapidity and safety (radioactive free detection) as well as in the possibility of having a reliable quantitative determination of UDG activity in both cell and tissue extracts. We also demonstrated the effectiveness of our method in assessing UDG activity in cell lines with a reduced DNA repair capacity and in different kinds of tissues. KEY MESSAGES: • Base excision repair is a fundamental repair mechanism ensuring the genome integrity. • Uracil is one of the most prevalent lesions that appears in DNA. • The mutagenic effects of uracil in DNA are mitigated by the uracil-DNA glycosylase. • Several assays evaluating the in vitro BER activity have been described so far. • A safe and quantitative assay evaluating the in vitro UDG activity is required.
Research on physiopathology of obesity may receive new hints from studies on skinny people (SP). These are individuals who show a poor or null gaining of body weight, in spite of high-calorie intake, by far exceeding the body requirements.
Mitochondrial dysfunction seems to play a fundamental role in the pathogenesis of neurodegeneration in Huntington's disease (HD). We assessed possible neuroprotective actions of meldonium, a small molecule affecting mitochondrial fuel metabolism, in in vitro and in vivo HD models. We found that meldonium was able to prevent cytotoxicity induced by serum deprivation, to reduce the accumulation of mutated huntingtin (mHtt) aggregates, and to upregulate the expression of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in mHTT-expressing cells. The PGC-1α increase was accompanied by the increment of mitochondrial mass and by the rebalancing of mitochondrial dynamics with a promotion of the mitochondrial fusion. Meldonium-induced PGC-1α significantly alleviated motor dysfunction and prolonged the survival of a transgenic HD Drosophila model in which mHtt expression in the nervous system led to progressive motor performance deficits. Our study strongly suggests that PGC-1α, as a master coregulator of mitochondrial biogenesis, energy homeostasis, and antioxidant defense, is a potential therapeutic target in HD.
Metabolic syndrome (MetS) is defined as the co-occurrence of metabolic risk factors that includes insulin resistance, hyperinsulinemia, impaired glucose tolerance, type 2 diabetes mellitus, dyslipidemia, and visceral obesity. The clinical significance of MetS consists of identifying a subgroup of patients sharing a common physiopathological state predisposing to chronic diseases. Clinical and scientific studies pinpoint lifestyle modification as an effective strategy aiming to reduce several features accountable for the risk of MetS onset. Among the healthy dietary patterns, the Mediterranean diet (MedDiet) emerges in terms of beneficial properties associated with longevity. Current evidence highlights the protective effect exerted by MedDiet on the different components of MetS. Interestingly, the effect exerted by polyphenols contained within the representative MedDiet components (i.e., olive oil, red wine, and nuts) seems to be accountable for the beneficial properties associated to this dietary pattern. In this review, we aim to summarize the principal evidence regarding the effectiveness of MedDiet-polyphenols in preventing or delaying the physiopathological components accountable for MetS onset. These findings may provide useful insights concerning the health properties of MedDiet-polyphenols as well as the novel targets destined to a tailored approach to MetS.
Mesenchymal stem cells, a subpopulation of mesenchymal stromal cells (MSCs), are present in the stroma of several tissues. MSC cultivation for clinical treatments may greatly affect MSC properties. A primary handicap is replicative senescence that impairs MSC functions. Hyaluronan (HA) is present in the extracellular matrix that composes the stem cell niche environment and is under investigation as a key factor for stem cell growth. We evaluated the effect on MSC cultivation of HA hybrid cooperative complexes (HCC) that are obtained from high (H) and low (L) weight molecules (NAHYCO™). We compared this HCC with H-HA and L-HA. We investigated the effects of these HAs on proliferation, cell cycle, apoptosis, senescence, and differentiation following the addition of the polymer solutions in the culture media at concentrations that did not drastically modify the medium viscosity. Interestingly, 0,16% HCC significantly delayed the senescence compared with the controls. This occurred without alteration of the cell cycle, cytotoxicity, or apoptosis. HCCs also promoted adipogenic and chondrogenic differentiation. Our finding could suggest a potential functional role of HCC above the updated scientific reports of its effects and pave the way to optimization of MSC cultivation for therapeutic application.
Mesenchymal stromal cells (MSCs) are considered to be an excellent source in regenerative medicine. They contain several cell subtypes, including multipotent stem cells. MSCs are of particular interest as they are currently being tested using cell and gene therapies for a number of human diseases. They represent a rare population in tissues; for this reason, they require, before being transplanted, an in vitro amplification. This process may induce replicative senescence, thus affecting differentiation and proliferative capacities. Increasing evidence suggests that MSCs from fetal tissues are significantly more plastic and grow faster than MSCs from bone marrow. Here, we compare amniotic fluid mesenchymal stromal cells (AF-MSCs) and bone marrow mesenchymal stromal cells (BM-MSCs) in terms of cell proliferation, surface markers, multidifferentiation potential, senescence, and DNA repair capacity. Our study shows that AF-MSCs are less prone to senescence with respect to BM-MSCs. Moreover, both cell models activate the same repair system after DNA damage, but AF-MSCs are able to return to the basal condition more efficiently with respect to BM-MSCs. Indeed, AF-MSCs are better able to cope with genotoxic stress that may occur either during in vitro cultivation or following transplantation in patients. Our findings suggest that AF-MSCs may represent a valid alternative to BM-MSCs in regenerative medicine, and, of great relevance, the investigation of the mechanisms involved in DNA repair capacity of both AF-MSCs and BM-MSCs may pave the way to their rational use in the medical field.
Exposure to high levels of ionizing radiation (IR) (>0.5Gy), negatively affect health. but, less is known about the effects of low dose IR (LDIR) but recent, evidence suggests that it may have profound effects on cellular functions. We are commonly exposed to LDIR over natural background levels from numerous sources: people may be exposed to low dose IR for medical diagnosis and therapy, air travel, illegal IR waste dumpsites or by occupational exposures in the nuclear and medical sectors. Stem cells reside for long periods of time in our bodies, and this increases the possibility that they may be accumulate genotoxic damage derived from extrinsic LDIR or intrinsic sources (such as DNA replication). In this review we provide an overview of LDIR effects on biology of stem cell compartments. The principal findings and issues reported in the scientific literature are discussed in order to present the current understanding of the LDIR exposure risk, and assess whether it may impact human health. We first consider the general biological consequences of LDIR exposure. Following this, we discuss the effects of LDIR on stem cells as discovered through in vitro and in vivo studies. This article is protected by copyright. All rights reserved.
Human mesenchymal stromal/stem cells (hMSCs) emerged as a promising therapeutic tool for ischemic disorders, due to their ability to regenerate damaged tissues, promote angiogenesis and reduce inflammation, leading to encouraging, but still limited results. The outcomes in clinical trials exploring hMSC therapy are influenced by low cell retention and survival in affected tissues, partially influenced by lesion's microenvironment, where low oxygen conditions (i.e. hypoxia) and inflammation coexist. Hypoxia and inflammation are pathophysiological stresses, sharing common activators, such as hypoxia-inducible factors (HIFs) and NF-κB. HIF1α and HIF2α respond essentially to hypoxia, activating pathways involved in tissue repair. Little is known about the regulation of HIF3α. Here we investigated the role of HIF3α in vitro and in vivo. Human MSCs expressed HIF3α, differentially regulated by pro-inflammatory cytokines in an oxygen-independent manner, a novel and still uncharacterized mechanism, where NF-κB is critical for its expression. We investigated if epigenetic modifications are involved in HIF3α expression by methylation-specific PCR and histone modifications. Robust hypermethylation of histone H3 was observed across HIF3A locus driven by pro-inflammatory cytokines. Experiments in a murine model of arteriotomy highlighted the activation of Hif3α expression in infiltrated inflammatory cells, suggesting a new role for Hif3α in inflammation in vivo.