The proliferating cell nuclear antigen (PCNA) protein serves as a molecular platform recruiting and coordinating the activity of factors involved in multiple deoxyribonucleic acid (DNA) transactions. To avoid dangerous genome instability, it is necessary to prevent excessive retention of PCNA on chromatin. Although PCNA functions during DNA replication appear to be regulated by different post-translational modifications, the mechanism regulating PCNA removal and degradation after nucleotide excision repair (NER) is unknown. Here we report that CREB-binding protein (CBP), and less efficiently p300, acetylated PCNA at lysine (Lys) residues Lys13,14,77 and 80, to promote removal of chromatin-bound PCNA and its degradation during NER. Mutation of these residues resulted in impaired DNA replication and repair, enhanced the sensitivity to ultraviolet radiation, and prevented proteolytic degradation of PCNA after DNA damage. Depletion of both CBP and p300, or failure to load PCNA on DNA in NER deficient cells, prevented PCNA acetylation and degradation, while proteasome inhibition resulted in accumulation of acetylated PCNA. These results define a CBP and p300-dependent mechanism for PCNA acetylation after DNA damage, linking DNA repair synthesis with removal of chromatin-bound PCNA and its degradation, to ensure genome stability.

A large body of evidence highlights that propolis exerts many biological functions that can be ascribed to its antioxidant and anti-inflammatory components, including different polyphenol classes. Nevertheless, the molecular mechanisms are yet unknown. The aim of this study is to investigate the mechanisms at the basis of propolis anti-inflammatory and antioxidant activities. The effects of two brown and green propolis extracts—chemically characterized by RP-HPLC-PDA-ESI-MSn—on the expression levels of miRNAs associated with inflammatory responses (miR-19a-3p and miR-203a-3p) and oxidative stress (miR-27a-3p and miR-17-3p), were determined in human keratinocyte HaCat cell lines, treated with non-cytotoxic concentrations. The results showed that brown propolis, whose major polyphenolic components are flavonoids, induced changes in the expression levels of all miRNAs, and was more active than green propolis (whose main polyphenolic components are hydroxycinnamic acid derivatives) which caused changes only in the expression levels of miR-19a-3p and miR-27a-3p. In addition, only brown propolis was able to modify (1) the expression levels of mRNAs, the target of the reported miRNAs, which code for Tumor Necrosis Factor-α (TNF-α), Nuclear Factor, Erythroid 2 Like 2 (NFE2L2) and Glutathione Peroxidase 2 (GPX2), and (2) the protein levels of TNF-α and NFE2L2. In conclusion, brown and green propolis, which showed different metabolite profiles, exert their biological functions through different mechanisms of action.

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OBJECTIVE:Neauvia Stimulate is biocompatible, injectable hyaluronic acid (HA) filler (26 mg/ml) PEG cross-linked with 1% of calcium hydroxyapatite (CaHA) for facial soft-tissue augmentation that provides volume to tissues, followed by process of neocollagenesis for improving skin quality.AIM:The aim of the present study is to evaluate the biosafety of the product (Lot. 160517-26-1/2 PEG) on human keratinocytes cultured in vitro.MATERIAL AND METHODS:The experimental model proposed, despite being an in vitro system, allows the derivation of useful information to predict the possible activity of the product in further in vivo application. Human keratinocytes (HaCaT cells) were treated with the product for 24h at increasing concentrations of product respect to control (untreated cells).RESULTS:The biosafety of the product to be tested has been evaluated performing different methods: MTT test, NRU test, Kenacid Blue assay. Moreover, any possible effect on the structure, morphology, and viability of cells has been evaluated.CONCLUSION:In conclusion, the results obtained by the different methods show that the product Neauvia Stimulate® does not cause any cytotoxic effect and does not affect the correct structure and morphology of cells cultures.

(2014) DDB2 association with PCNA is required for its degradation after UV-induced DNA damage, Cell Cycle, 13:2, 240-248,