Selenium maintains Ca2+ homeostasis in sheep lymphocytes challenged by oxidative stress

Abstract

Selenium (Se) is an essential element in human and animal diets, based upon a widespread range of beneficial effects that are primarily due to its antioxidant properties. While Se can be associated to anti-cancer and anti-diabetic activities, reproductive efficiency, and enhancement of the immune system, the mechanistic details of the corresponding biological processes are still largely elusive. To avoid deficiencies and increase bioavailability, Se it is generally supplied to livestock through Se-supplemented feeds or forage plants fertilized with inorganic Se. While the relationship between Ca2+ and ROS (reactive oxygen species) is well known, only a few studies have addressed the possible involvement of Se in the control of cytosolic Ca2+ in oxidative stress. The results on Ca2+ homeostasis were obtained adding exogenous Se in the form of SeO42- to sheep lymphomonocytes cultured in vitro. In particular, Se strongly attenuated 1mM H2O2-induced alteration of intracellular [Ca2+]C as well as the entry of extracellular Ca2+ into the cells with comparable EC50 values for sodium selenate accounting to 1.72 and 2.28 mM, respectively. In an ex vivo trial, it was observed that Ca2+ homeostasis can effectively be rescued in sheep lymphomonocytes exposed in vivo to a Se concentration of approximately 1.9 mM, that was achieved by feeding sheep with olive leaves previously sprayed with 500 mg/plant Na-selenate. Thus the results obtained suggest that the mode of action of selenium markedly influenced Ca2+-related signaling events. Furthermore, results clearly reveal that the protective effect of Se on Ca2+ homeostasis under oxidative challenge can be clearly and effectively achieved through an appropriate dietary regimen obtained also in a circular economy logic using pruning of olive trees treated to reduce tree drought stress.

Selenium maintains cytosolic Ca2+ homeostasis and preserves germination rates of maize pollen under H2O2-induced oxidative stress

“…With the overall objective of assessing the antioxidant potential of Se, we initially tested the impact of oxidative stress on levels of cytosolic Ca 2+ . To this end, 1–20 mM H 2 O 2 , a range previously found to be optimal for cell-based procedures 37 , was included with resuspended aliquots of pollen.…”

“…Our experimental setup implied field maize fertigation with sodium selenate, isolation of pollen from plants and, subsequently, application of H 2 O 2 in pollen preparations to raise oxidative stress in vitro . Conditions related to fertigation, and the setup of the cellular oxidative model were previously established (shown in refs 9,37 ., respectively).…”

“…ROS act like agonists by either stimulating the mobilization of the ion from internal Ca 2+ stores such as endoplasmic reticulum, Golgi vesicles and vacuoles 30 , or activating the Ca 2+ entry from the extracellular medium, thereby disrupting the thousands-fold gradient between nanomolar and micromolar concentrations that the cell tightly maintains in the cytosolic and the extracellular space, respectively 25,31–36 . A large body of literature describes the interaction between ROS and Ca 2+ , however only scant information exists about the effect of either inorganic or organic Se in the relationship between ROS, Ca 2+ signals and pollen germination 25,31,37 .…”

Selenium-Enriched Pollen Grains of Olea europaea L.: Ca2+ Signaling and Germination Under Oxidative Stress

“…Furthermore, the germinated pollen grains and the elongated pollen tubules require an internal Ca 2+ gradient, which is maintained by an extracellular ion supply (Michard et al, 2009;Steinhorst and Kudla, 2013). Therefore, in light of the well-documented bidirectional relationship between ROS, which can modulate cellular calcium-dependent networks, and calcium signaling, which plays a key role in ROS assembly (Steinhorst and Kudla, 2013;Görlach et al, 2015;Proietti et al, 2018), we decided to use cytosolic Ca 2+ as a final point for monitoring the perturbations caused by oxidative stress.…”

“…The mobile phase consisted of ammonium acetate with gradient elution. The analytical method and instrumental conditions have been described previously (Proietti et al, 2018).…”