Selenium and selenoproteins: it's role in regulation of inflammation

Abstract

Selenium is an essential immunonutrient which holds the human's metabolic activity with its chemical bonds. The organic forms of selenium naturally present in human body are selenocysteine and selenoproteins. These forms have a unique way of synthesis and translational coding. Selenoproteins act as antioxidant warriors for thyroid regulation, male-fertility enhancement, and anti-inflammatory actions. They also participate indirectly in the mechanism of wound healing as oxidative stress reducers. Glutathione peroxidase (GPX) is the major selenoprotein present in the human body, which assists in the control of excessive production of free radical at the site of inflammation. Other than GPX, other selenoproteins include selenoprotein-S that regulates the inflammatory cytokines and selenoprotein-P that serves as an inducer of homeostasis. Previously, reports were mainly focused on the cellular and molecular mechanism of wound healing with reference to various animal models and cell lines. In this review, the role of selenium and its possible routes in translational decoding of selenocysteine, synthesis of selenoproteins, systemic action of selenoproteins and their indirect assimilation in the process of wound healing are explained in detail. Some of the selenium containing compounds which can acts as cancer preventive and therapeutics are also discussed. These compounds directly or indirectly exhibit antioxidant properties which can sustain the intracellular redox status and these activities protect the healthy cells from reactive oxygen species induced oxidative damage. Although the review covers the importance of selenium/selenoproteins in wound healing process, still some unresolved mystery persists which may be resolved in near future.

Keywords: Gpxs; ROS; SEPP1; SEPS1; Selenium; Selenium drugs; Selenoproteins; Wound healing.

Fig. 1

Selenium uptake and accumulation in plants (ST Sulfur transport channels, SeO₄ selenate, APSe adenosine phosposelenate, PAPSe phospho adenosine phospho selenite, OASO-acetyl serine, OPHO-phospho hemoserine, DMSe dimethylselenide; products are shown in purple color. Metabolites are shown in orange color)

Fig. 2

The dietary intake and initial metabolism of selenium in the human body (SPS2 selenophosphate synthase 2, tRNA^Sec tRNA for selenocysteine, EMT epithelial-to-mesenchymal transition)

Fig. 3

Biosynthesis of selenoproteins/translational decoding (tRNA^Sec tRNA for selenocysteine, SARS Seryl-tRNA sythetase, PSTK phosphoseryl-tRNA kinase, PSer phosphoserine, SPS2 selenophosphate synthase 2, SeCysS selenocysteine synthase, SeCys selenocysteine, SBP2 selenocysteine incorporation sequence binding protein 2, SECIS selenocysteine insertion sequence, EFsec specialized elongation factor, HSe⁻ hydrogen selenide)

Fig. 4

Synthesis and transport of selenoproteins (GPX Glutathione peroxidases, TRXR thioredoxin reductases, SEPP selenoprotein P, SEP15 15-kDa selenoprotein, SelK selenoprotein K, SelS selenoprotein S, DIOs iodothyronine deiodinases, T3 3,5,3′-triiodothyronine)

Fig. 5

Role of selenoproteins (GPXs, TrxRs, Sel P and Sel S) during wound healing process (GPXs GPX-Glutathione peroxidases, TrxRs thioredoxin reductases, SelKselenoprotein K, SelS selenoproteinS)