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Webinar 2021

How to attend the Webinars

We will use the Zoom platform. To attend the meeting, simply join us at the link that will be published 1 h in advance.

On April 20th, please join us here

 

Spring 2021 edition of the SIMAG Webinars

After the success of the First webinar series held in Autumn 2020, the Italian Society of Environmental Mutagenesis and Genomics (SIMAG) is launching the Spring 2021 edition, to improve communication and discussion in this period of travel restrictions.

Prof. Silvio de Flora, honorary member and former President of the Society, will open this second Webinar Series.  In continuity with the First Webinar series, the following  presentations will be held by new SIMAG members, as well as by young components of research groups active in the Society.

This page will be upadated with the Abstracts of each Webinar.

 

20th April 2021, 2.30-3.30 pm - Click here to attend the Webinar

Silvio De Flora, Roumen Balansky and Sebastiano La Maestra

Department of Health Sciences, University of Genova, 16132 Genova (sdf@unige.it)

Cancer prevention and COVID-19 prevention. Antioxidant mechanisms

 Abstract:

Oxidative stress is a key mechanism in the pathogenesis of virtually all chronic degenerative diseases such as cancer, atherosclerosis and other cardiovascular diseases, neurological disorders, dysmetabolic conditions, rheumatoid arthritis, etc., as well as in ageing processes. Importantly, oxidative stress is also involved in the pathogenesis of many infectious diseases, also including COVID-19. Therefore, in spite of their obvious clinical diversities, cancer and COVID-19 may share protective mechanisms based on modulation of the oxidoreductive balance.

The classical strategy for the primary prevention of cancer and other mutation-related diseases, which is addressed to apparently healthy individuals, consists in avoidance of exposures to recognized risk factors, which involves preliminary risk assessments and mechanistic studies. Typical examples of carcinogenic risk factors include inappropriate food and dietary factors; tobacco smoke, either mainstream or environmental or transplacental; chronic infections and infestations; exposure to UV-containing light. A complementary strategy, to which more and more importance is given nowadays, is chemoprevention, which involves dietary and pharmacological interventions aimed at interfering with the carcinogenesis process via a large variety of mechanisms. We performed several tens studies evaluating a number of putative chemopreventive agents, among which antioxidant agents, in experimental test systems in vitro and in vivo as well as in clinical trials.

SARS-CoV-2, the etiological agent of COVID-19, is one of the hundreds of viruses that cause respiratory diseases, which have a tremendous epidemiological impact in the population worldwide. Oxidative mechanisms contribute to the pathogenesis of these diseases, as demonstrated in a broad number of experimental studies. A pioneer clinical trial evaluating the thiol N-acetylcysteine (NAC) is the only published study that  provided evidence for the ability of antioxidants to significantly attenuate the incidence of influenza and influenza-like illnesses (ILI) (Eur. Respir. J. 10, 1535-41, 1997). A variety of antioxidants have been proposed for the control of COVID-19. The glutathione circuit, involving the interconversion between GSSG (glutathione disulfide) and GSH (reduced glutathione), is the key player against SARS-CoV-2.  GR (GSSG reductase) is increased in COVID-19 patients but this is not sufficient to restore the GSH stores depleted by the viral infection. Hence, it is necessary to promote GSH synthesis by administering GSH analogues and precursors, such as NAC. The impairment of G6PD and NADPH causes GSH depletion, and the intravenous administration of NAC has beneficial effects in G6PD-deficient subject suffering from severe forms of COVID-19. NAC and GSH work via a network of interconnected mechanisms (FASEB J. 34, 1385-93, 2020). Based on computational studies, these thiols are expected to inhibit binding of the virus spikes to the cellular ACE2 receptor. We designed  an experimental study that will evaluate the ability of NAC to inhibit penetration of a SARS-Cov-2 pseudovirus into ACE2-expressing cells. The potent antioxidant activity of NAC, as a scavenger of ROS, is interconnected with its antiinflammatory and immunomodulatory activities. For instance, one of them involves inhibition by NAC-GSH of the ROS-mediated activation of the transcription factor NF-κB and consequent inhibition of proinflammatory genes that are known to play a role in COVID-19 pathogenesis, such as interleukins, prostaglandins, cyclooxygenases, tumor necrosis factor-α, and metalloproteases. In parallel, NAC-GSH further stimulate the other factor Nrf2, which attenuates inflammation by promoting the transcription of factors mediated by anti-inflammatory genes such as  NQO-1 (quinone oxidoreductase) and HO-1 (heme-oxygenase-1).

Thus, the daily administration of oral NAC or other drugs having antioxidant, antiinflammatory and immunomodulatory properties may contribute to attenuate the risk of developing COVID-19, irrespective of variants, and at the same time to protect against influenza and ILI as well as against the co-morbidities associated with GSH depletion, also including cancer. In addition, as an adjuvant therapy, NAC may contribute to control COVID-19 alterations when injected intravenously at the very high doses that are successfully used worldwide as an antidote against paracetamol intoxication. Besides being hepatotoxic, paracetamol depletes GSH stores and, rather than being curative, may favour COVID-19 complications.

 

4th May 2021, 2.30-3.00 pm

Giulio Ticli1, I. Dutto1, C. Scalera1, O. Cazzalini2, L. A. Stivala2, A. Rapp3, M. C. Cardoso3, E. Prosperi1.

1Institute of Molecular Genetics, CNR, via Abbiategrasso 207, 27100, Pavia, Italy
2Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy.
3Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany.Dr. Giulio Ticli, Istituto di Genetica Molecolare, Pavia, Italy

Study of p21CDKN1A activity on PCNA-partners dynamics in Nucleotide Excision Repair (NER)

 Abstract:

 The p21CDKN1A protein is involved in several cellular processes including cell cycle regulation, transcription, apoptosis, cell motility, and DNA repair. In particular, p21 participates in the Nucleotide Excision Repair (NER) through interaction with Proliferative Cell Nuclear Antigen (PCNA). In this study we have investigated whether p21 may influence the dynamics of PCNA-interacting partners, such as DNA Polymerase (Pol) δ and DNA Ligase (Lig) 1, at the DNA damage sites. For this purpose, we have used two different p21 mutant plasmids: K161Q, K163Q (p212KQ) and KRR154-156AAA (p21AAA), both expressing a stable protein, because after DNA damage p21 is known to be degraded with a PCNA-dependent mechanism.

These proteins were transiently expressed as GFP-tagged proteins in HeLa cells, or in a cell clone constitutively expressing mCherry-PCNA. In some experiments, cells were also transfected with a plasmid coding for DNA Lig 1 fused to monomeric-infrared RFP (miRFP-DNA Lig1). An immunoprecipitation assay was first performed to test the ability of p21 mutants to bind PCNA: only the p212KQ, but not the p21AAA mutant, retained the ability to interact with PCNA, similarly to p21WT. Then, live cell imaging analyses were performed to test the recruitment and release kinetics of all fluorescently-tagged proteins. While the recruitment kinetics of p21-GFP, mCherry-PCNA and miRFP-DNA Lig 1 were not affected by p212KQ, nor by the absence of the protein, compared with p21WT, their release kinetics were significantly different. Indeed, the mCherry-PCNA release was slower in the presence of p212KQ mutant (t1/2: 2984 s) and in the absence of p21 (t1/2: 3239 s), than in the presence of p21WT (t1/2: 2513 s). In addition, as well as mCherry-PCNA, miRFP-DNA Lig 1 showed a slower release kinetics, both in the presence of p212KQ (t1/2: 2823 s) and in the absence of p21 (t1/2: 3111 s), compared with p21WT protein (t1/2: 1704 s). As expected, due to lack of PCNA binding, the p21AAA was not recruited to DNA damage sites. Successively, immunofluorescence assays were performed to investigate the influence of p212KQ mutant on DNA Pol δ release from the DNA damage sites, revealing that after UV irradiation (3h and 6h) also the DNA Pol δ is retained on damaged DNA for a longer time in HeLa cells expressing p212KQ, compared with those expressing p21WT. Finally, to investigate the effect of p21 persistence at DNA damage sites on the efficiency of NER, we determined the amount of EdU incorporation in non-S phase cells expressing p21WT or mutant protein. The results showed that the DNA repair efficiency was significantly reduced by about 25%, both in the presence of p212KQ and in the absence of p21, compared with WT protein.

These findings together suggest that the exchange of PCNA partners, at least during NER, is regulated by p21, with a mechanism which may be coupled to p21 degradation, thereby temporally defining PCNA-dependent steps of NER.

 

18th May 2021, 2.30-3.00 pm

Dr. Dimitrios Spiliotopoulos, Xenometrix AG, Allschwil, Germany

Validation of a miniaturized Ames test in a liquid microplate format: Ames MPF

 

1st June, 2.30-3.00 pm

Ettore Meccia, Istituto Superiore Sanità, Roma, Italy

What's in the black box? Taking basic research to population studies

 

Abstract:

We are all constantly exposed to chemicals contained in water, air, food, medicines, drugs, cosmetics, health care products, clothes, furniture, everything we use, throughout our lives, during pregnancy and even before conception.   The same applies to living organisms in the natural environment. Many of these substances are completely new and very little is known about their toxicity and the risk they pose to our health. Furthermore, we are typically exposed to a mix of chemical substances in which single substance toxicity could add up to the others although by different mechanisms and pathways.

For these reasons, we need new tools and new approaches to assess both already known and new mechanisms of toxicity.

On one side much effort is being done applying new technologies to well established assays (for instance Comet assay) to get them more sensitive, less error prone or automated and high throughput. But on the other side a continuous flow of knowledge and technology from basic science to epidemiological studies and toxicity assessment is essential to find out new tools.

Thanks to basic science progression, new knowledge is constantly achieved in human physiology, pathology and diseases, like early events or predisposing factors in inflammatory processes, carcinogenesis or neurodegeneration. All of this knowledge is translated into better diagnostic tools, new drugs design, new therapies. However, it must even be translated into new approaches and new tools to understand adverse outcomes from exposure to environmental chemicals.

We have long been studying causes and consequences of oxidative damage to DNA, both genomic and mitochondrial, as well as  to RNA. So we are trying to convert some of our experimental approaches (like changes in the mitochondrial DNA copy number) into biomarkers of effects to be used in population studies.

Likewise, we are studying epigenetic changes in a mother-child cohort to understand if and how some chemicals can interact with biological systems and to associate exposure to postnatal or later in life outcomes.

About the First SIMAG Webinar Series (2020)

20 November 2020 - 2.30 pm

Andrea Stoccoro and Fabio Coppedè (Università di Pisa, Pisa) “Mitochondrial epigenetics in neurodegenerative  diseases”.

Abstract:

Neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS), represent a group of complex disorders resulting from the interaction between genetic and non-genetic factors. Epigenetic mechanisms, such as DNA methylation, are able to change gene expression under the influence of environmental factors and their deregulation has been suggested to contribute to the neurodegenerative process. Indeed, several epigenetic changes in nuclear DNA have been documented post-mortem in brain regions of patients affected by major neurodegenerative diseases, as well as in animal models of those disorders, paving the way to the search of peripheral epigenetic biomarkers of neurodegeneration. Increasing evidence suggests that changes in DNA methylation occur also in mitochondrial DNA (mtDNA), likely regulating both mtDNA replication and gene expression levels, and it has been observed that altered mtDNA methylation could contribute to the aetiology of several complex human diseases, including neurodegenerative ones. The majority of these studies investigated DNA methylation levels of the mtDNA regulatory region (D-loop), which plays a fundamental role in regulating mtDNA replication and transcription, revealing that D-loop methylation levels were dysregulated in central nervous system tissues of AD and ALS animal models, and were significantly different from those seen in human postmortem AD and PD brains compared to healthy controls. However, none of those studies investigated mtDNA methylation levels in specimens from living patients.

In our laboratory we investigated D-loop methylation levels in peripheral blood of patients with different neurodegenerative diseases, including late-onset AD and ALS, observing altered methylation levels in AD patients and in sporadic ALS patients, as well as in ALS patients with germinal causative mutations in the SOD1 gene compared to healthy matched controls. Our results also suggested that D-loop methylation levels were able to regulate mtDNA replication. Moreover we identified polymorphisms of genes related to DNA methylation reactions that significantly associated with D-loop methylation levels. Overall our results suggest that D-loop methylation and mitochondrial replication are strictly related to each other and their evaluation could provide useful information for a better understanding of the etiopathology underlying neurodegenerative diseases, as well as useful disease biomarkers.

In this webinar we will discuss the results of our investigation of mtDNA methylation levels in patients with late-onset AD, ALS, PD, as well as preliminary results in AD individuals at the very early stage of the disease.

 

 

20 November 2020 - 3.00 pm

Fabrizio Bianchi (Fondazione Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia) “Deciphering cancer transcriptomics to improve diagnostics and therapeutics”.

 

Abstract:

Lung cancer is the first cause of cancer related death worldwide. Although low-dose CT can definitely contribute to increase the percentage of tumors diagnosed at early stage (stage I) in lung screening programs (Aberle et al., N Engl J Med 2011; Zhao et al., Cancer Imaging 2011), a significant fraction of these patients (~30%) still experience recurrence and acquire chemoresistance (Siegel et al., CA Cancer J Clin 2018). Using a multi-tiered approach relying on multiomics we found that early stage but aggressive lung cancer is characterized by loss of pulmonary lineage, gain of EMT/stem-like features, alongside the occurrence of mutator and immune-evasion phenotypes. We refined a gene expression signature diagnostic of this aggressive lung cancer molecular subtype which surpasses current prognostic biomarkers and former molecular classifications. Our results pave the way for development of new therapeutic approaches for early stage lung cancer.

 

28 October 2020 - 2.30 pm
Valeria Simonelli (Istituto Superiore di Sanità, Roma) “High-fat diet, oxidative damage and susceptibility to chronic-degenerative diseases: a pilot study in transgenic mice”.

Abstract:

Several lines of evidence, obtained both in murine models and in epidemiological studies, show that an increase in body fat mass is linked to oxidative stress and that the accumulation of radical oxygen species (ROS) contributes to develop the metabolic syndrome (Marseglia et al., Int J Mol Sci. 2015).

ROS induce DNA damage with a consequent activation of DNA damage response (DDR), an orchestrated set of proteins which are able to trigger early/late and intra/extra-cellular warnings (Rodier et al., Nature Cell Biol. 2009; Malaquin et al., Frontiers in Genetics 2015).

Mice defective in DNA damage processing genes are highly susceptible to obesity if exposed to high-fat diet (HFD) (Sampath et al. PLOS ONE 2012; Sampath et al., Am. J. Physiol. Endocrinol. Metab. 2011; Chen et al. PNAS 2015). This evidence suggests a link between genomic instability and metabolic dysfunction. 

In our laboratory we have obtained a transgenic mouse which expresses high levels of the human MutT homologue (hMTH1). MTH1 is a hydrolase which is able to protect cells by oxidative damage by removing oxidized precursors (8-oxodGTP e 2-OHdATP) from pool of nucleotides, thus avoiding their incorporation in DNA. Interestingly, when compared with wild-type counterpart, our transgenic mouse (hMTH1-Tg) shows: a) protection against neurodegeneration induced by treatment with 3-nitropropionic acid, which causes symptoms that resemble those of Huntington's disease (De Luca et al, PLOS Genetics 2008); b) a decrease in oxidative damage, both in nuclear and in mitochondrial DNA; c) an increased longevity (De Luca et al., Aging Cell 2013); d) a delay in the ageing process; e) a reduced anxiety and an enhanced investigation of environmental and social cues; f) a best mitochondrial functionality.

Our preliminary data suggest that MTH1 plays a pivotal role in modulating oxidative DNA damage in response to HFD. The ongoing Nuclear Magnetic Resonance spectroscopy/imaging and neuro-behavioral analysis will help to clarify the role of oxidative stress and response to oxidative damage in the modulation of risk of chronic-degenerative diseases.

 

28 October 2020 - 3.00 pm
Laura Bisini (European Research Biology Center, Pomezia, Roma) “Performance improvement for in vitro genotoxicity testing: the experience of a CRO”.

Abstract:

Information on genotoxicity is a key component of the safety assessment for all type of substances whatever their use and intended purpose. The three major endpoints involved in carcinogenesis and heritable diseases (gene mutation, structural and numerical chromosome damage) need to be evaluated and testing requirements across different regulatory sectors usually include two or three validated in vitro tests in order to cover these endpoints. According to the type of test chemical under regulation and the region, in vivo assays may be required as follow-up studies in case of positive results in any of the in vitro genotoxicity studies.

Based on this, it is evident that the in vitro test battery plays a key role in the genotoxicity assessment and special care and considerable expertise and experience are required to ensure that the outcome is not misleading due to the intrinsic potential of these assays to generate false negative and positive results. In order to reach valid conclusions and limit at the same time the use of animals, it is necessary to be aware of the reasons which could lead to misleading results (e.g. in vitro metabolism, non physiological conditions, extreme toxicity) and to enhance in vitro testing performance.

Thanks to the variety of substances analyzed and the number of studies conducted, the experience of a CRO can give an important contribution to further investigate possible critical areas of improvement.

Several case studies will be illustrated giving real examples of the experimental approaches applied during the assessment of genotoxicity.

 

30 November 2020 -2.30 pm

Bartolomeo Bosco and Alberto Inga (Università di Trento, Trento) “Translational controls in p53-dependent responses: exploring the role of the RNA helicase DHX30”.

Abstract:

p53 is a critical tumor suppressor protein, and, consistently, it is mutated or lost in about 50% of all human cancers. Traditionally, research has focused on p53’s role as a sequence-specific transcription factor that becomes activated in response to several stress stimuli and orchestrates various cell responses through an extensive transcriptional network. However, recent findings have added translational control as another critical layer of the p53 response. Our group has described that enhanced translation of pro-apoptotic mRNAs carrying one or several so-called CGPD motifs (CG-rich motif mediating p53-dependent death) in their 3’-UTR can shift the cellular response towards apoptosis in p53 wild-type cancer cells. Intriguingly, this translational impact on CGPD-containing transcripts can be counteracted by specific RNA binding proteins (RBPs), which have been demonstrated to associate with and possibly shield the CGPD motif. One such protein is the RNA helicase DHX30. Indeed, DHX30 depletion enhanced p53-dependent apoptosis in cancer cells treated with the MDM2 inhibitor nutlin-3, and its overexpression led to the reduced translation of pro-apoptotic CGPD-containing transcripts. However, our recent work revealed that DHX30 exhibits a more general function in translation control by integrating the activities exerted by one isoform expressed in the cytoplasm and another, more abundant, localized to the mitochondria. Results based on both stable and transient DHX30 depletion, including the selective silencing of the cytoplasmic isoform, lead us to propose that DHX30 contributes to cell homeostasis by coordinating ribosome biogenesis, global translation, and mitochondrial metabolism. Notably, a gene signature comprising DHX30 and fourteen mitoribosome protein transcripts that are its candidate direct targets showed prognostic value in distinct cancer types of the TGCA dataset.

 

 

30 November 2020 - 3.00 pm

Giulia Vecchiotti, Massimo Aloisi and Anna MG Poma (Università dell’Aquila, L’Aquila) “Cyto and genotoxicity of polystyrene nanoparticles in vitro”.

Abstract:

Plastics materials are the most spread polymers-based physicals since they were invented in the middle of 19th century to stand in for the ivory usage and elephants extinction. Nowadays they are a real environmental and health emergency. In fact every year more than 300 tons are produced worldwide and they are spilled in the environment. Therefore they are considered as emergent pollutants. Once they are spread in different frameworks they, in several years, are deteriorated in smaller particles called micro- and nanoplastics. The first ones have a diameter in the range of 101 nm and 5 mm; the second ones have a diameter lower than 100 nm.