The miR166d/TaCPK7-D Signaling Module Is a Critical Mediator of Wheat (Triticum aestivum L.) Tolerance to K+ Deficiency.

It is well established that potassium (K+) is an essential nutrient for wheat (Triticum aestivum L.) growth and development. Several microRNAs (miRNAs), including miR166, are reportedly vital roles related to plant growth and stress responses. In this study, a K+ starvation-responsive miRNA (miR166d) was identified, which showed increased expression in the roots of wheat seedlings exposed to low-K+ stress. The overexpression of miR166d considerably increased the tolerance of transgenic Arabidopsis plants to K+ deprivation treatment. Furthermore, disrupting miR166d expression via virus-induced gene silencing (VIGS) adversely affected wheat adaptation to low-K+ stress. Additionally, miR166d directly targeted the calcium-dependent protein kinase 7-D gene (TaCPK7-D) in wheat. The TaCPK7-D gene expression was decreased in wheat seedling roots following K+ starvation treatment. Silencing TaCPK7-D in wheat increased K+ uptake under K+ starvation. Moreover, we observed that the miR166d/TaCPK7-D module could affect wheat tolerance to K+ starvation stress by regulating TaAKT1 and TaHAK1 expression. Taken together, our results indicate that miR166d is vital for K+ uptake and K+ starvation tolerance of wheat via regulation of TaCPK7-D.

Molecular Dynamics Simulation Study on Interactions of Cycloviolacin with Different Phospholipids.

Cyclotides are disulfide-rich cyclic peptides isolated from plants, which are extremely stable against thermal and proteolytic degradation, with a variety of biological activities including antibacterial, hemolytic, anti-HIV, and anti-tumor. Most of these bioactivities are related to their preference for binding to certain types of phospholipids and subsequently disrupt lipid membranes. In the present study, we use a cyclotide, cycloviolacin O2 (cyO2), as a model system to investigate its interactions with three lipid bilayers 1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG)-doped POPE, and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), to help understand its potential mechanism of action toward the membranes at the molecular level using molecular dynamics simulations. In our simulations, cyO2 repeatedly forms stable binding complexes with the POPE-containing bilayers, while within the same simulation time scale, it "jumps" back and forth on the surface of the POPC bilayer without a strong binding. Detailed analyses reveal that the electrostatic attraction is the main driving force for the initial bindings between cyO2 and the lipids, but with strikingly different strengths in different bilayers. For the POPE-containing bilayers, the charged residues of cyO2 attract both POPE amino and phosphate head groups favorably; meanwhile, its hydrophobic residues are deeply inserted into the lipid hydrophobic tails (core) of the membrane, thus forming stable binding complexes. In contrast, POPC lipids with three methyl groups on the amino head group create a steric hindrance when interacting with cyO2, thus resulting in a relatively difficult binding of cyO2 on POPC compared to POPE. Our current findings provide additional insights for a better understanding of how cyO2 binds to the POPE-containing membrane, which should shed light on the future cyclotide-based antibacterial agent design.

Quercetin regulates ERα mediated differentiation of BMSCs through circular RNA.

Circular RNA (circRNA) participates in regulation of gene transcription, while estrogen receptor alpha (ERα) and quercetin (QUE) positively regulate bone formation, but little is known about the correlation among circRNA, ERα and QUE. In this experiment, we created an ERα-deficient rBMSC model treated with QUE and evaluated the effects of ERα or QUE on rBMSCs, then analyzed differentially-expressed circRNAs by RNA-Seq and bioinformatics. The results showed that ERα deficiency constrained osteogenic differentiation and stimulated adipocytic differentiation of rBMSCs, while QUE abrogated those effects. We identified 136 differentially-expressed circRNAs in the Lv-shERα group and 120 differentially-expressed circRNAs in the Lv-shERα + QUE group. Thirty-two circRNAs retroregulated by ERα and QUE were involved in Rap1 and Wnt signaling, and four of them together sponged miR-326-5p, the target genes of which are osteogenic and adipogenic differentiation factors. Further study showed that over-expressed miR-326-5p could stimulate osteogenic differentiation, while attenuating adipogenic differentiation of rBMSCs. Therefore, we concluded that ERα and QUE might regulate the differentiation of rBMSCs through the circRNA-miR-326-5p-mRNA axis.

Quercetin exerts antidepressant and cardioprotective effects in estrogen receptor α-deficient female mice via BDNF-AKT/ERK1/2 signaling.

Brain-derived neurotrophic factor (BDNF) is the potential link between depression and cardiovascular disease and estrogen receptor α (ERα), an estrogen-mediated major regulator, plays an important role in protecting against depression and cardiovascular disease. However, the relationship between BDNF and ERα remains obscure. Herein, quercetin (QUE), a kind of plant flavonoids and existed in many vegetables and fruits, was found to simultaneously reverse ERα-/--induced depression-like and cardiac dysfunction by reducing immobility time in the tail suspension test (TST) and forced swimming test (FST), and decreasing systolic blood pressure and activating the apoptosis-related proteins, BDNF, tropomyosin-related kinase B (TrkB), protein kinase B (AKT), and extracellular regulatory protein kinase (ERK1/2) in the hippocampal and cardiac tissues of female mice. These findings suggested that ERα might be involved in the regulation of BDNF activity, thereby regulating depression-like and cardiovascular responses in female mice, and QUE exerted significant antidepressant and cardioprotective effects, at least in part, through BDNF-TrkB-AKT/ERK1/2 to effectively inhibit ERα-/--induced hippocampal and cardiac dysfunction.

MiR-210-3p inhibits osteogenic differentiation and promotes adipogenic differentiation correlated with Wnt signaling in ERα-deficient rBMSCs.

MicroRNAs (miRNAs) regulate activities in living organisms through various signaling pathways and play important roles in the development and progression of osteoporosis. The balance between osteogenic and adipogenic differentiation of rBMSCs is closely related to the occurrence of osteoporosis. ERα regulates bone metabolism in various tissues. However, the correlation among ERα, miRNAs, and the differentiation of rBMSCs is still unclear. In this study, we used lentivirus transfection into rBMSCs to construct an ERα-deficient model, analyzed the differences in expressed miRNAs between control and ERα-deficient rBMSCs. The results revealed that the expression of 25 miRNAs were upregulated, 164 miRNAs were downregulated, and some of the regulated miRNAs such as miR-210-3p and miR-214-3p were related to osteogenic or adipogenic differentiation, as well as to particular signaling pathways. Next, we overexpressed miR-210-3p to evaluate its effects on the osteogenic and adipogenic differentiation of rBMSCs, and identified the relationship among miR-210-3p, Wnt signaling pathway, and the differentiation of rBMSCs. The results indicated that ERα-deficient inhibited osteogenic differentiation, promoted adipogenic differentiation, and regulated the expression of some miRNAs. Meanwhile, overexpression of miR-210-3p promoted osteogenic differentiation and inhibited adipogenic differentiation of rBMSCs, processes likely to be related to the Wnt signaling pathway. In conclusion, we identified a group of upregulated and downregulated miRNAs in ERα-deficient rBMSCs that might play a vital role in regulating osteogenic or adipogenic differentiation. One of these, miR-210-3p, inhibited osteogenic differentiation and promoted adipogenic differentiation correlated with the Wnt signaling pathway in ERα-deficient rBMSCs, providing new insight into the regulation of bone metabolism.

Icariin stimulates osteogenic differentiation and suppresses adipogenic differentiation of rBMSCs via estrogen receptor signaling.

Icariin (ICA) is a major active ingredient in Herba epimedii, which is commonly used as a Chinese herbal medicine for the treatment of osteoporosis. Previous studies have revealed that ICA exerted a protective effect against bone loss and increased bone regeneration; however, the association between ICA and estrogen receptor (ER) signaling remains unclear. The aim of the present study was to determine the effect of ICA on rat bone marrow stromal cells (rBMSCs). Cell Counting Kit­8 assays were conducted to measure proliferation, alkaline phosphatase (ALP) activity was evaluated to assess osteoblast differentiation, and reverse transcription­quantitative polymerase chain reaction as well as western blotting were performed to detect the expression of cellular and molecular markers of osteogenic or adipogenic differentiation. The results demonstrated that treatment of rBMSCs with 10­6 M ICA stimulated rBMSC proliferation and ALP activity. Furthermore, ICA treatment increased the expression of the osteogenic markers runt­related transcription factor 2, collagen type 1 and bone morphogenetic Protein 2; however, it also decreased the expression of the adipogenic differentiation markers peroxisome proliferator­activated receptor gamma and CCAAT/enhancer­binding protein α. Treatment of rBMSCs with ICI182780, an ER antagonist, blocked the effects of ICA. Taken together, these findings indicated that ICA may stimulate osteoblast differentiation and inhibit adipogenic differentiation via the activation of the ER signaling pathway. Therefore, ICA has the potential to serve as a therapeutic alternative for the prevention and treatment of osteoporosis.