Abstract
Aging is characterized by increase in reactive oxygen (ROS) and nitrogen (RNS) species, key factors of cardiac failure and disuse-induced muscle atrophy. This study focused on serum nitroproteome as a trait of longevity by adopting two complementary gel-based techniques: two-dimensional differential in gel electrophoresis (2-D DIGE) and Nitro-DIGE coupled with mass spectrometry of albumin-depleted serum of aged (A, n = 15) and centenarian (C, n = 15) versus young females (Y, n = 15). Results indicate spots differently expressed in A and C compared to Y and spots changed in A vs. C. Nitro-DIGE revealed nitrosated protein spots in A and C compared to Y and spots changed in A vs. C only (p-value < 0.01). Nitro-proteoforms of alpha-1-antitripsin (SERPINA1), alpha-1-antichimotripsin (SERPINA3), ceruloplasmin (CP), 13 proteoforms of haptoglobin (HP), and inactive glycosyltransferase 25 family member 3 (CERCAM) increased in A vs. Y and C. Conversely, nitrosation levels decreased in C vs. Y and A, for immunoglobulin light chain 1 (IGLC1), serotransferrin (TF), transthyretin (TTR), and vitamin D-binding protein (VDBP). Immunoblottings of alcohol dehydrogenase 5/S-nitrosoglutathione reductase (ADH5/GSNOR) and thioredoxin reductase 1 (TRXR1) indicated lower levels of ADH5 in A vs. Y and C, whereas TRXR1 decreased in A and C in comparison to Y. In conclusion, the study identified putative markers in C of healthy aging and high levels of ADH5/GSNOR that can sustain the denitrosylase activity, promoting longevity.
Highlights
Longevity is the result of multiple factors including genetic, epigenetic, and lifestyle; circulating molecules able to predict the evolution from healthy toward stressor events overwhelming the antioxidant capacity of the entire organism are still absent
Aging is characterized by a progressive decline of the muscle functional performance, which contributes to frailty, defined as the vulnerability of the body to exogenous and endogenous stressors [1]
The ryanodine receptor 1 (RYR1) nitrosation is directly related to the loss of muscle mass and function [9,10], and its regulation is a critical condition for the muscular homeostasis maintenance
Summary
Longevity is the result of multiple factors including genetic, epigenetic, and lifestyle; circulating molecules able to predict the evolution from healthy toward stressor events overwhelming the antioxidant capacity of the entire organism are still absent. We expect that nitrosation of proteins could be a more general event and we assume that markers of nitrosative stress can be found in cardiac and skeletal muscle tissues and in bodily fluids In this context, we would like to understand if there is a relationship between circulating biomarkers and loss of muscle mass and function or if other mechanisms contribute to longevity. ADH5/GSNOR regulates intracellular concentration of reactive NO by catalyzing the breakdown of S-nitrosoglutathione (GSNO), a NO donor for cysteine thiols, indirectly modulating SNO formation through GSNO-mediated protein S-nitrosation This suggests that these two systems target different molecules, since GSNOR denitrosates GSNO, whereas the cytoplasmic and mitochondrial thioredoxins mediate denitrosation of multiple S-nitrosated proteins in relation to stimulus, substrate, and localization [30]. In an attempt to find modified molecules involved into the aging process and in the loss of muscle mass characterizing aging, we adopted a two-dimensional difference in gel electrophoresis (2-D DIGE) gel-based analysis of the serum proteome in conjunction with Nitro-DIGE and mass spectrometry of aged (A) women versus young (Y) women and centenarians (C) in order to identify putative markers associated with aging
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