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Reactive oxygen species (ROS) are essential signaling molecules that enable cells to respond rapidly to a range of stimuli. The ability of plants to recognize various stressors, incorporate a variety of environmental inputs, and initiate stress-response networks depends on ROS. Plants develop resilience and defensive systems as a result of these processes. Root hairs are central components of root biology since they increase the surface area of the root, anchor it in the soil, increase its ability to absorb water and nutrients, and foster interactions between microorganisms. In this review, we specifically focused on root hair cells and we highlighted the identification of ROS receptors, important new regulatory hubs that connect ROS production, transport, and signaling in the context of two hormonal pathways (auxin and ethylene) and under low temperature environmental input related to nutrients. As ROS play a crucial role in regulating cell elongation rates, root hairs are rapidly gaining traction as a very valuable single plant cell model for investigating ROS homeostasis and signaling. These promising findings might soon facilitate the development of plants and roots that are more resilient to environmental stressors.

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Although iron is essential for all forms of life, it is also potentially toxic to cells as the increased and unregulated iron uptake can catalyze the Fenton reaction to produce reactive oxygen species (ROS), leading to lipid peroxidation of membranes, oxidation of proteins, cleavage of DNA and even activation of apoptotic cell death pathways. We demonstrate that Fe(hinok)3 (hinok = 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), a neutral Fe(III) complex with high lipophilicity is capable of bypassing the regulation of iron trafficking to disrupt cellular iron homeostasis; thus, harnessing remarkable anticancer activity against a panel of five different cell lines, including Pt-sensitive ovarian cancer cells (A2780; IC50 = 2.05 ± 0.90 µM or 1.20 µg/mL), Pt-resistant ovarian cancer cells (A2780cis; IC50 = 0.92 ± 0.73 µM or 0.50 µg/mL), ovarian cancer cells (SKOV-3; IC50 = 1.23 ± 0.01 µM or 0.67 µg/mL), breast cancer cells (MDA-MB-231; IC50 = 3.83 ± 0.12 µM or 2.0 µg/mL) and lung cancer cells (A549; IC50 = 1.50 ± 0.32 µM or 0.82 µg/mL). Of great significance is that Fe(hinok)3 exhibits unusual selectivity toward the normal HEK293 cells and the ability to overcome the Pt resistance in the Pt-resistant mutant ovarian cancer cells of A2780cis.

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Abiotic and biotic factors induce oxidative stress involving the production and scavenging of reactive oxygen species (ROS). This review is a survey of well-known and possible roles of serine-threonine protein phosphatases in plant oxidative stress signaling, with special emphasis on PP2A. ROS mediated signaling involves three interrelated pathways: (i) perception of extracellular ROS triggers signal transduction pathways, leading to DNA damage and/or the production of antioxidants; (ii) external signals induce intracellular ROS generation that triggers the relevant signaling pathways and (iii) external signals mediate protein phosphorylation dependent signaling pathway(s), leading to the expression of ROS producing enzymes like NADPH oxidases. All pathways involve inactivation of serine-threonine protein phosphatases. The metal dependent phosphatase PP2C has a negative regulatory function during ABA mediated ROS signaling. PP2A is the most abundant protein phosphatase in eukaryotic cells. Inhibitors of PP2A exert a ROS inducing activity as well and we suggest that there is a direct relationship between these two effects of drugs. We present current findings and hypotheses regarding PP2A-ROS signaling connections related to all three ROS signaling pathways and anticipate future research directions for this field. These mechanisms have implications in the understanding of stress tolerance of vascular plants, having applications regarding crop improvement.

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Objective To explore the inhibitory effect of curcumin on LPS-induced inflammation and the activation of Toll-like receptor 4 (TLR4 )/NADPH oxidase/reactive oxygen species (ROS)signaling pathway in vascular smooth muscle cells (VSMCs).Methods Primary VSMCs were cultured and divided into control group, LPS group,LPS + curcumin 5 μmol/L group,LPS + curcumin 10 μmol/L group and LPS + curcumin 30 μmol/L group.Cell activity was observed by MTT assay.The secretion of tumor necrosis factor-α(TNF-α)and interleukin-1 (IL-1)was measured by enzyme linked immunosorbent assay (ELISA)kits.The mRNA expressions of TLR4 and p22phox were detected by real-time PCR.Expression of intracellular ROS was measured by flow cytometry. Results The activities of VSMCs were not significantly affected by curcumin at the concentration between 0 and 80 μmol/L.Curcumin (5,10 and 30 μmol/L)significantly inhibited LPS-induced oversecretion of TNF-αand IL-1, as well as overexpression of TLR4 and p22phox at the mRNA and protein levels,and ROS production in VSMCs in a concentration-dependent manner.Conclusion Curcumin has a concentration-dependent inhibitory effect on the secretion of inflammatory cytokine,overexpressions of TLR4 and p22phox,and production of ROS in VSMCs stimulated by LPS.Furthermore,curcumin may partly depend on TLR4/NADPH oxidase/ROS signaling pathways to inhibit inflammation in LPS-induced VSMCs.