Bianchi, Anna Rita (2015) Lipidomic and poly(ADP-ribose) polymerase automodification analyses as laboratory tools to detect the physio-pathological state of the cell. [Tesi di dottorato]

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Abstract

Membrane lipid peroxidation and DNA damage are the main and most studied consequences of free radicals. The mechanisms underlying these deleterious processes are mostly known and there are increasing evidence that they might be modulated by a correct quality of food intake and post-translational modification reactions (namely poly(ADP-ribosyl)ation), respectively. Poly(ADP-ribosyl)ation, catalysed by poly(ADP-ribose) polymerases, affects many cellular events and has a recognized epigenetic role. Nuclear poly(ADP-ribose) polymerases 1 and 2 are hyperactivated by DNA strand breaks. They auto-modify with large polymers of ADP-ribose and recruit DNA repair proteins. The more the DNA strand breaks, the more poly(ADP-ribose) polymerase modifies itself. On the other hand, dietary lipids can be signaling molecules, lead to pro-(ω6)/anti-(ω3) inflammatory compounds, and be included in biomembranes, good biomarkers of their unbalance. Here, we report the results obtained from a study to establish whether the combination of two different analyses, i.e. detecting auto-modified poly(ADP-ribose) polymerase levels and analyzing erythrocyte membrane fatty acid composition, might help to monitor the physio-pathological state of the cell, and to correlate with lifestyle, diet or diseases. The two analyses were carried blindly on 95 subjects undergoing endoscopy. They were first interviewed, to collect anamnesis and clinical data, if present. Lymphocytes and erythrocytes were prepared from venous blood to assay poly(ADP-ribose) polymerase automodification and membrane fatty acid content, respectively. The results were statistically evaluated. The measure of poly(ADP-ribose) polymerase automodification confirmed that its levels correlate with DNA damage extent, within the same pathology, and allowed to monitor the clinical activity of the disease, depending on ongoing surgical/therapeutic treatment. Membrane fat profile was able to evidence unbalance of lipids linked to both diet/lifestyle and inflammatory states leading to diseases. In most analysed cases, each test demonstrated to evidence, separately, specific features of the physio-pathological state of the subject, i.e. membrane lipid unbalance, altered function(s) of specific pathways of DNA and/or lipid metabolism. In other cases, a correlation between both analyses and specific pathologies emerged. This finding suggested that in the laboratory routine, combining the two tests might be a preliminary step to investigate the occurrence of a given disease, before confirming the diagnosis with other specific clinical analyses. Both PARP automodification and membrane lipidomic profile provide possible biomarkers for sensible, non-invasive and routine monitoring.

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