Interplay between Selenium Levels and Replicative Senescence in WI-38 Human Fibroblasts: A Proteomic Approach.

Ghania Hammad,Laurent Chavatte,Zahia Touat-Hamici,David Cornu,Anne-Laure Bulteau,Stéphane Duhieu,Yona Legrain

doi:10.3390/antiox7010019

Abstract

Selenoproteins are essential components of antioxidant defense, redox homeostasis, and cell signaling in mammals, where selenium is found in the form of a rare amino acid, selenocysteine. Selenium, which is often limited both in food intake and cell culture media, is a strong regulator of selenoprotein expression and selenoenzyme activity. Aging is a slow, complex, and multifactorial process, resulting in a gradual and irreversible decline of various functions of the body. Several cellular aspects of organismal aging are recapitulated in the replicative senescence of cultured human diploid fibroblasts, such as embryonic lung fibroblast WI-38 cells. We previously reported that the long-term growth of young WI-38 cells with high (supplemented), moderate (control), or low (depleted) concentrations of selenium in the culture medium impacts their replicative lifespan, due to rapid changes in replicative senescence-associated markers and signaling pathways. In order to gain insight into the molecular link between selenium levels and replicative senescence, in the present work, we have applied a quantitative proteomic approach based on 2-Dimensional Differential in-Gel Electrophoresis (2D-DIGE) to the study of young and presenescent cells grown in selenium-supplemented, control, or depleted media. Applying a restrictive cut-off (spot intensity ±50% and a p value < 0.05) to the 2D-DIGE analyses revealed 81 differentially expressed protein spots, from which 123 proteins of interest were identified by mass spectrometry. We compared the changes in protein abundance for three different conditions: (i) spots varying between young and presenescent cells, (ii) spots varying in response to selenium concentration in young cells, and (iii) spots varying in response to selenium concentration in presenescent cells. Interestingly, a 72% overlap between the impact of senescence and selenium was observed in our proteomic results, demonstrating a strong interplay between selenium, selenoproteins, and replicative senescence.

Highlights

Selenium has been shown to be an essential trace element in all animals
We have further investigated the interrelation between selenium and replicative senescence at the molecular level using a proteomic approach
We have recently shown that selenium levels in the culture medium modulated the proliferative capacity of WI-38 [13]

Summary

Introduction

Selenium has been shown to be an essential trace element in all animals. Most of the beneficial effects of selenium are due to the existence of a pool of selenoproteins, which are involved in redox biology and homeostasis. The selenoproteins have the ability to translationally incorporate a rare amino acid residue, selenocysteine (Sec, U), using a specific and complex machinery (for details, see [4]). The selenocysteine residue is more reactive and less sensitive to oxidation than its sulfur analog cysteine. At the catalytic site of enzymes, selenocysteine participates in redox reactions, which are essential for antioxidant defense, redox homeostasis, and cell signaling [5,6,7,8]. Gene inactivation in mice of certain selenoproteins, such as glutathione peroxidase 4

Methods

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Discussion

Conclusion