Identification of the 2-tridecanone cis-acting element in the promoter of cytochrome P450 CYP6B7 in Helicoverpa armigera

The NAC gene family in the halophyte Limonium bicolor: Identification, expression analysis, and regulation of abiotic stress tolerance

NAC transcription factors regulate plant growth, development, and stress responses. However, the number, types, and biological functions of Limonium bicolor LbNAC genes have remained elusive. L. bicolor secretes excessive salt ions through salt glands on its stems and leaves to reduce salt-induced damage. Here, we identified 63 NAC members (LbNAC1-63) in L. bicolor, which were unevenly distributed across eight chromosomes. Cis-elements in the LbNAC promoters were related to growth and development, stress responses, and phytohormone responses. We observed strong colinearity between LbNACs and GmNACs from soybean (Glycine max). Thus, LbNAC genes may share similar functions with GmNAC genes. Expression analysis indicated that 16 LbNAC genes are highly expressed in roots, stems, leaves, and flowers, whereas 17 LbNAC genes were highly expressed throughout salt gland development, suggesting that they may regulate this developmental stage. Silencing LbNAC54 in L. bicolor decreased salt gland density, salt secretion from leaves, and overall salt tolerance. In agreement, genes related to salt gland development were significantly downregulated in LbNAC54-silenced lines. Our findings shed light on LbNAC genes and help elucidate salt gland development and salt secretion in L. bicolor. Our data also provide insight into NAC functions in halophytes.

Identification and characterization of both cis- and trans-regulators mediating fenvalerate-induced expression of CYP6B7 in Helicoverpa armigera

As we known, inducibility is an important feature of P450 genes. Previous studies indicated that CYP6B7 could be induced and involved in fenvalerate detoxification in Helicoverpa armigera. However, the regulatory mechanism of CYP6B7 induced by fenvalerate is still unclear. In this study, CYP6B7 promoter of H. armigera was cloned and the cis-acting element of fenvalerate was identified to be located between -84 and - 55 bp of CYP6B7 promoter. Subsequently, 33 candidate transcription factors (CYP6B7-fenvalerate association proteins, CAPs) that may bind to the cis-acting element were screened and verified by yeast one-hybrid. Among them, the expression levels of several CAPs were significantly induced by fenvalerate. Knockdown of juvenile hormone-binding protein-like (JHBP), RNA polymerase II-associated protein 3 (RPAP3), fatty acid synthase-like (FAS) and peptidoglycan recognition protein LB-like (PGRP) resulted in significant expression inhibition of CYP6B7, and increased sensitivity of H. armigera to fenvalerate. Co-transfection of reporter gene p (-84/-55) with pFast-CAP showed that JHBP, RPAP3 and PGRP could significantly increase the activity of CYP6B7 promoter. These results suggested that trans-acting factors JHBP, RPAP3 and PGRP may bind with cis-acting elements to regulate the expression of CYP6B7 induced by fenvalerate, and play an important role in the detoxification of H. armigera to fenvalerate.

Study on SH-SY5Y autophagy inhibition and apoptosis induced by methanol extract of Zanthoxylum armatum DC. based on mTOR signal pathway

Background

Zanthoxylum armatum DC. (ZADC) is a novel food raw material resource, offering both edible and medicinal properties. Recent research has unveiled the toxic nature of ZADC, particularly its close association with the nervous system. In a prior study, we observed that administering methanol extract of Zanthoxylum armatum DC. (MZADC) to rats via gavage at a dose of 1.038 g/kg resulted in various neurotoxicity symptoms, including excessive salivation, reduced mobility, unsteady gait, muscle twitching, and altered respiratory rates.

Materials and methods

We conducted cell-based research to assess the safety of ZADC and elucidate its potential toxic mechanism. In addition, we used experimental methods such as Cell Counting Kit-8, Western blot, and Flow cytometry to detect cytotoxicity in SH-SY5Y cells after intervention with MZADC.

Results

Following exposure of SY-SY5Y cells with MZADC, a substantial decline in cell viability was observed, accompanied by a concentration-dependent increase in intracellular reactive oxygen species (ROS) levels. Additionally, MZADC induced cellular oxidative stress, leading to elevated malonic dialdehyde (MDA) and superoxide dismutase (SOD) concentrations while decreasing glutathione (GSH) levels. Furthermore, MZADC induced apoptosis at varying doses (20, 40, and 60 μg/mL), and this effect was associated with increased Caspase-3, Bax expressions, and reduced Bcl2 and Bcl2/Bax expressions. In addition, the investigation revealed that MZADC induced autophagy inhibition in SH-SY5Y cells by activating the mTOR signaling pathway, resulting in a decrease in LC3II/LCI and Beclin-1, while increasing p-mTOR/mTOR, p62.

Conclusion

Consequently, this study suggests that MZADC triggers the mTOR pathway through oxidative stress in SH-SY5Y cells, ultimately leading to apoptosis. Understanding the toxicity mechanisms associated with ZADC can offer a valuable theoretical and experimental basis for its development and utilization.

Identification of insect cuticular protein genes LCP17 and SgAbd5 from Helicoverpa armigera and evaluation their roles in fenvalerate resistance

Insect cuticular protein (ICP) plays an important role in insect growth and development. However, research on the role of ICP in insecticide resistance is very limited. In this study, insect cuticular protein genes LCP17 and SgAbd5 were cloned and characterized in Helicoverpa armigera based on previous transcriptome data. The functions of LCP17 and SgAbd5 genes in fenvalerate resistance were assessed by RNA interference (RNAi), and their response to fenvalerate was further detected. The results showed that LCP17 and SgAbd5 were overexpressed in the fenvalerate-resistant strain comparing with a susceptible strain. The open reading frames of LCP17 and SgAbd5 genes were 423 bp and 369 bp, encoding 141 and 123 amino acids, respectively. LCP17 and SgAbd5 genes were highly expressed in the larval stage, but less expressed in the adult and pupal stages. The expression level of LCP17 and SgAbd5 genes increased significantly after fenvalerate treatment at 24 h. When the cotton bollworms larvae were exposed to fenvalerate at LD50 level, RNAi-mediated silencing of LCP17 and SgAbd5 genes increased the mortality from 50.68% to 68.67% and 63.89%, respectively; the mortality increased to even higher level, which was 73.61%, when these two genes were co-silenced. Moreover, silencing of these two genes caused the cuticle lamellar structure to become loose, which led to increased penetration of fenvalerate into the larvae. The results suggested that LCP17 and SgAbd5 may be involved in the resistance of cotton bollworm to fenvalerate, and LCP17 and SgAbd5 could serve as potential targets for H. armigera control.

Neurotoxicity study of ethyl acetate extract of Zanthoxylum armatum DC. on SH-SY5Y based on ROS mediated mitochondrial apoptosis pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zanthoxylum armatum DC. (ZADC) is a traditional medicinal plant with various pharmacological activities and is widely used in China, Japan, India, and other regions. Previous studies have revealed that the methanol extract of ZADC can cause neurotoxicity symptoms in rats, such as drooling, decreased appetite, decreased movement, and increased respiratory rate. However, the basis of these toxic substances and the mechanism of neurotoxicity remain unclear.

AIM OF THE STUDY

To evaluate the effects of ZADC on nerve cells and their damage mechanisms and discuss the possible toxic substance basis.

MATERIALS AND METHODS

The ethyl acetate extract of ZADC is obtained by extracting the methanol extract of ZADC with ethyl acetate. The Q-Orbitrap LC-MS/MS method was employed to analyze the chemical composition of the EA extract of ZADC. SH-SY5Y cells were incubated with different concentrations of the ethyl acetate extract of ZADC. The cytotoxicity of the extract was evaluated using CCK-8, LDH, and ROS assays, and the oxidative stress status of cells was assessed using MDA, GSH, and SOD. Cell apoptosis was detected using flow cytometry. Damage to mitochondrial function was evaluated by labeling mitochondria, ATP, and MMP with fluorescence. Cyto-C, Caspase-3, Caspase-9, Apaf-1, Bax, and reduced Bcl2 expression were measured to evaluate the activation of the mitochondrial apoptosis pathway. Finally, NAC intervention was used to detect changes in the relevant indicators. The activation of mitochondrial apoptosis pathway was evaluated by measuring Cyto-C, Caspase-3, Caspase-9, Apaf-1, and Bax and Bcl2 expression. Finally, NAC intervention was utilized to detect changes in the relevant indicators.

RESULTS

After treating SY-SY5Y cells with EA extract from ZADC, cell viability decreased significantly, and the intracellular ROS level increased in a dose-dependent manner. Meanwhile, ZADC can cause cellular oxidative stress and increase MDA and SOD concentrations while decreasing GSH concentrations. It can also shorten the mitochondrial cristae and decrease the number of mitochondria. In contrast, it can reduce ATP synthesis in the mitochondria and mitochondrial membrane potential (MMP). Furthermore, it increased the apoptosis rate and the expression of Cyto-C, Caspase-3, Caspase-9, Apaf-1, and Bax and reduced Bcl2 expression. NAC intervention alleviated the reduction in SH-SY5Y cell survival and the accumulation of reactive oxygen species induced by the EA extract in ZADC. It also inhibits signaling pathways dominated by proteins, such as Cyto-C, reducing cell apoptosis and cytotoxicity. A total of 46 compounds were identified in the extracts.

CONCLUSIONS

The results suggest that EA extract of ZADC can induce the mitochondrial apoptotic pathway by accumulating ROS in cells, leading to apoptosis. Antioxidants had a good inhibitory and protective effect against cell damage caused by the EA extract of ZADC. The neurotoxic components of ZADC may be organic acids and compounds containing amino groups.

Identification of cis-acting elements in response to fenvalerate in the CYP6B7 promoter of Helicoverpa armigera

Cytochrome P450-mediated detoxification plays an important role in the development of insecticide resistance. Previous studies have shown that cytochrome P450 CYP6B7 was induced by fenvalerate and involved in fenvalerate detoxification in Helicoverpa armigera. However, the transcriptional regulation of CYP6B7 induced by fenvalerate remains unclear. Here, a series of progressive 5' deletions of CYP6B7 promoter reporter genes were constructed, and the relative luciferase activities were detected. The results revealed that the relative luciferase activity of plasmid p (-655/-1) was significantly induced by fenvalerate. Further deletion of the region between -655 and -486 bp showed that the highest luciferase activity induced by fenvalerate was observed in plasmid p (-528/-1), while p (-485/-1) had the lowest fenvalerate-induced luciferase activity. Moreover, internal deletion and mutation in the region between -508 and -486 bp resulted in a significant reduction in fenvalerate-induced CYP6B7 promoter activity, suggesting that the cis-acting element responsible for fenvalerate in the CYP6B7 promoter was located between -508 and -486 bp. These results promote an understanding of the expression regulation mechanism of P450 genes that conferring resistance to insecticides.

Regulation of insect P450s in response to phytochemicals

Insect herbivores use phytochemicals as signals to induce expression of their phytochemical-detoxifying cytochrome P450 monooxygenases (P450s). The regulatory cascades that transduce phytochemical signals to enhanced expression of P450s are the focus of this review. At least seven signaling pathways, including RTK/MAPK, GPCR/CREB, GPCR/NFκB, ROS/CncC/Keap1, AhR/ARNT, cytosol NR, and nucleus-located NR, may be involved in phytochemical induction of P450s. Constitutive overexpression, overphosphorylation, and/or activation of one or more effectors in the corresponding pathway are common causes of P450 overexpression that lead to phytochemical or insecticide resistance. Future research should pay more attentions to the starting point of each pathway, the number of pathways and their cross talk for a given phytochemical, and the pathways for downregulation of P450s.

Short term transcriptional responses of P450s to phytochemicals in insects and mites

Cytochrome P450 monooxygenases (P450s) play a key role in the detoxification of phytochemicals in arthropod herbivores. We present here an overview of recent progress in understanding the breadth and specificity of gene expression plasticity of P450s in response to phytochemicals. We discuss experimental setups and new findings in mechanisms of P450 regulation. Whole genome transcriptomic analysis of arthropod herbivores, either after direct administration of phytochemicals or after host plant shifts, allowed to integrate various levels of chemical complexity and lead to the unbiased identification of responsive P450 genes. However, despite progress in identification of inducible P450s, the link between induction and metabolism is still largely unexplored, and to what extent the overall response is biologically functional should be further investigated. In the near future, such studies will be more straightforward as forward and reverse genetic tools become more readily available.