Dysregulation of iron homeostasis and ferroptosis in sevoflurane and isoflurane associated perioperative neurocognitive disorders.

In recent years, sevoflurane and isoflurane are the most popular anesthetics in general anesthesia for their safe, rapid onset, and well tolerant. Nevertheless, many studies reported their neurotoxicity among pediatric and aged populations. This effect is usually manifested as cognitive impairment such as perioperative neurocognitive disorders. The wide application of sevoflurane and isoflurane during general anesthesia makes their safety a major health concern. Evidence indicates that iron dyshomeostasis and ferroptosis may establish a role in neurotoxicity of sevoflurane and isoflurane. However, the mechanisms of sevoflurane- and isoflurane-induced neuronal injury were not fully understood, which poses a barrier to the treatment of its neurotoxicity. We, therefore, reviewed the current knowledge on mechanisms of iron dyshomeostasis and ferroptosis and aimed to promote a better understanding of their roles in sevoflurane- and isoflurane-induced neurotoxicity.

Cyanidin-3-O-glucoside Contributes to Leaf Color Change by Regulating Two bHLH Transcription Factors in Phoebe bournei.

Anthocyanins produce different-colored pigments in plant organs, which provide ornamental value. Thus, this study was conducted to understand the mechanism of anthocyanin synthesis in ornamental plants. Phoebe bournei, a Chinese specialty tree, has high ornamental and economic value due to its rich leaf color and diverse metabolic products. Here, the metabolic data and gene expression of red P. bournei leaves at the three developmental stages were evaluated to elucidate the color-production mechanism in the red-leaved P. bournei species. First, metabolomic analysis identified 34 anthocyanin metabolites showing high levels of cyanidin-3-O-glucoside (cya-3-O-glu) in the S1 stage, which may suggest that it is a characteristic metabolite associated with the red coloration of the leaves. Second, transcriptome analysis showed that 94 structural genes were involved in anthocyanin biosynthesis, especially flavanone 3'-hydroxy-lase (PbF3'H), and were significantly correlated with the cya-3-O-glu level. Third, K-means clustering analysis and phylogenetic analyses identified PbbHLH1 and PbbHLH2, which shared the same expression pattern as most structural genes, indicating that these two PbbHLH genes may be regulators of anthocyanin biosynthesis in P. bournei. Finally, overexpression of PbbHLH1 and PbbHLH2 in Nicotiana tabacum leaves triggered anthocyanin accumulation. These findings provide a basis for cultivating P. bournei varieties that have high ornamental value.

Genome-Wide Identification and Expression Analysis of Calmodulin and Calmodulin-like Genes, Revealing CaM3 and CML13 Participating in Drought Stress in Phoebe bournei.

Calmodulin (CaM) and calmodulin-like (CML) proteins are major Ca2+ sensors involved in the regulation of plant development and stress responses by converting Ca2+ signals into appropriate cellular responses. However, characterization and expression analyses of CaM/CML genes in the precious species, Phoebe bournei, remain limited. In this study, five PbCaM and sixty PbCML genes were identified that only had EF-hand motifs with no other functional domains. The phylogenetic tree was clustered into 11 subgroups, including a unique clade of PbCaMs. The PbCaMs were intron-rich with four EF-hand motifs, whereas PbCMLs had two to four EF-hands and were mostly intronless. PbCaMs/CMLs were unevenly distributed across the 12 chromosomes of P. bournei and underwent purifying selection. Fragment duplication was the main driving force for the evolution of the PbCaM/CML gene family. Cis-acting element analysis indicated that PbCaMs/CMLs might be related to hormones, growth and development, and stress response. Expression analysis showed that PbCaMs were generally highly expressed in five different tissues and under drought stress, whereas PbCMLs showed specific expression patterns. The expression levels of 11 candidate PbCaMs/CMLs were responsive to ABA and MeJA, suggesting that these genes might act through multiple signaling pathways. The overexpression of PbCaM3/CML13 genes significantly increased the tolerance of yeast cells to drought stress. The identification and characterization of the CaM/CML gene family in P. bournei laid the foundation for future functional studies of these genes.

Identification and Validation of Ferroptosis-Related Genes in Sevoflurane-Induced Hippocampal Neurotoxicity.

Background: Sevoflurane is one of the most popular inhalational anesthetics during perioperative period but presenting neurotoxicity among pediatric and aged populations. Recent experiments in vivo and in vitro have indicated that ferroptosis may contribute to the neurotoxicity of sevoflurane anesthesia. However, the exact mechanism is still unclear. Methods: In current study, we explored the differential expressed genes (DEGs) in HT-22 mouse hippocampal neuronal cells after sevoflurane anesthesia using RNA-seq. Differential expressed ferroptosis-related genes (DEFRGs) were screened and analyzed by Gene Ontology (GO) and pathway enrichment analysis. Protein-to-protein interaction (PPI) network was constructed by the Search Tool for the Retrieval of Interacting Genes (STRING). Significant modules and the hub genes were identified by using Cytoscape. The Connectivity Map (cMAP) was used for screening drug candidates targeting the identified DEFRGs. Potential TF-gene network and drug-gene pairs were established towards the hub genes. In final, we validated these results in experiments. Results: A total of 37 ferroptosis-related genes (18 upregulated and 19 downregulated) after sevoflurane exposure in hippocampal neuronal cells were finally identified. These differentially expressed genes were mainly involved into the biological processes of cellular response to oxidative stress. Pathway analysis indicated that these genes were involved in ferroptosis, mTOR signaling pathway, and longevity-regulating pathway. PPI network was constructed. 10 hub genes including Prkaa2, Chac1, Arntl, Tfrc, Slc7a11, Atf4, Mgst1, Lpin1, Atf3, and Sesn2 were found. Top 10 drug candidates, gene-drug networks, and TFs targeting these genes were finally identified. These results were validated in experiments. Conclusion: Our results suggested that ferroptosis-related genes play roles in sevoflurane anesthesia-related hippocampal neuron injury and offered the hub genes and potential therapeutic agents for investigating and treatment of this neurotoxicity after sevoflurane exposure. Finally, therapeutic effect of these drug candidates and function of potential ferroptosis targets should be further investigated for treatment and clarifying mechanisms of sevoflurane anesthesia-induced neuron injury in future research.

Sevoflurane exposure induces neurotoxicity by regulating mitochondrial function of microglia due to NAD insufficiency.

Developmental neurons received with sevoflurane, the commonly used inhalational anesthetic agent in clinical surgery, several times tend to be destroyed. Microglia, the resident immune cells of the central nervous system (CNS), are activated after sevoflurane exposure, accompanied by releasing proinflammatory cytokines that damage developing neurons. The sevoflurane-induced neurotoxicity could be attributed to activated microglia presenting proinflammatory and anti-inflammatory functions. Proinflammatory microglia release cytokines to impair the CNS, while anti-inflammatory microglia engulf damaged neurons to maintain CNS homeostasis. Sevoflurane exposure promotes the secretion of proinflammatory cytokines by microglia, inhibiting the microglial phagocytic function. Microglia with poor phagocytic function cannot engulf damaged neurons, leading to the accumulation of damaged neurons. The mechanism underlying poor phagocytic function may be attributed to mitochondrial dysfunction of microglia induced by sevoflurane exposure, in which affected mitochondria cannot generate adequate ATP and NAD to satisfy the energy demand. We discovered that sevoflurane treatment impaired the mitochondrial metabolism of microglia, which resulted in NAD deficiency and couldn't produce sufficient energy to clear damaged neurons to maintain CNS development. Our findings provide an explanation of a new mechanism underlying sevoflurane-induced neurotoxicity.