G protein-coupled receptors function as cell membrane receptors for the steroid hormone 20-hydroxyecdysone

20-hydroxyecdysone suppresses bladder cancer progression via inhibiting USP21: A mechanism associated with deubiquitination and degradation of p65

Bladder cancer is one of the most common malignancies of the urinary tract and a prevalent cancer worldwide, still requiring efficient therapeutic agents and approaches. 20-Hydroxyecdysone (20-HE), a steroid hormone, can be found in insects and few plants and mediate numerous biological events to control the progression of varying diseases; however, its impacts on bladder cancer remain unclear. In the study, we found that 20-HE treatments effectively inhibited the viability and proliferation of bladder cancer cells and induced apoptosis by activating Caspase-3. The migratory and invasive potential of bladder cancer cells was markedly repressed by 20-HE in a dose-dependent manner. The inhibitory effects of 20-HE on bladder cancer were confirmed in an established xenograft mouse model, as indicated by the markedly reduced tumor growth rates and limited lung and lymph node metastasis. High-throughput RNA sequencing was performed to explore dysregulated genes in bladder cancer cells after 20-HE treatment. We identified ubiquitin-specific protease 21 (USP21) as a key deubiquitinating enzyme for bladder cancer progression and a positive correlation between USP21 and nuclear factor-κB (NF-κB)/p65 in patients. Furthermore, 20-HE treatments markedly reduced USP21 expression, NF-κB/p65 mRNA, stability and phosphorylated NF-κB/p65 expression levels in bladder cancer cells, which were validated in animal tumor tissues. Mechanistic studies showed that USP21 directly interacted with and stabilized p65 by deubiquitinating its K48-linked polyubiquitination in bladder cancer cells, which could be abolished by 20-HE treatment, contributing to p65 degradation. Finally, we found that USP21 overexpression could not only facilitate the proliferation, migration, and invasion of bladder cancer cells, but also significantly eliminated the suppressive effects of 20-HE on bladder cancer. Notably, 20-HE could still perform its anti-tumor role in bladder cancer when USP21 was knocked down with decreased NF-κB/p65 expression and activation, revealing that USP21 suppression might not be the only way for 20-HE during bladder cancer treatment. Collectively, all our results clearly demonstrated that 20-HE may function as a promising therapeutic strategy for bladder cancer treatment mainly through reducing USP21/p65 signaling expression.

Effects of pyriproxyfen on development and hormone of the aphis, Aphis craccivora (Hemiptera: Aphididae)

Pyriproxyfen (PPF) has been shown to affect the pupal stage and ecdysone levels in holometabolous insects, such as silkworms and mealworms. It remains unknown whether it affects hemimetabolous insects with their hormone levels in insects lacking a pupal stage. In this laboratory study, bioassays were conducted to investigate the effects of varying doses of PPF on Aphis craccivora Koch (Hemiptera: Aphididae). Ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to determine the types and titers of juvenile hormone (JH) and 20-hydroxyecdysone (20E). Additionally, the effects of PPF on A. craccivora reproduction and molting, as well as its influence on relevant gene expression, were examined. The results revealed LC50 and LC90 values of 3.84 and 7.49 mg/l for PPF, respectively, after 48 h of exposure. The results demonstrated a significant reduction in the titer of JH III and a significant increase in the titer of 20E following treatment with PPF. However, there was no significant decrease observed in the titer of JH III skipped bisepoxide (JH SB3). A sublethal concentration of PPF was found to inhibit Krüppel homolog 1 (kr-h1) gene expression and reduce aphid reproduction, but it did not significantly impact ecdysone receptor expression and aphid molting. The results of this study demonstrate that PPF exhibits a lethal effect on aphids, thereby providing an effective means of control. Additionally, sublethal concentrations of PPF have been found to inhibit the JH in aphids, resulting in a decline in their reproductive ability and achieving the desired control objectives.

A relaxin receptor gene RpGPCR41 is involved in the resistance of Rhopalosiphum padi to pyrethroids

Rhopalosiphum padi is a global pest that poses a significant threat to wheat crops and has developed resistance to various insecticides. G protein-coupled receptors (GPCRs), known for their crucial role in signaling and biological processes across insect species, have recently gained attention as a potential target for insecticides. GPCR has the potential to contribute to insect resistance through the regulation of P450 gene expression. However, GPCRs in R. padi remained unexplored until this study. We identified a total of 102 GPCRs in R. padi, including 81 receptors from family A, 10 receptors from family B, 8 receptors from family C, and 3 receptors from family D. Among these GPCR genes, 16 were up-regulated in both lambda-cyhalothrin and bifenthrin-resistant strains of R. padi (LC-R and BIF-R). A relaxin receptor gene, RpGPCR41, showed the highest up-regulated expression in both the resistant strains, with a significant increase of 14.3-fold and 22.7-fold compared to the susceptible strain (SS). RNA interference (RNAi) experiments targeting the relaxin receptor significantly increase the mortality of R. padi when exposed to the LC50 concentration of lambda-cyhalothrin and bifenthrin. The expression levels of five P450 genes (RpCYP6CY8, RpCYP6DC1, RpCYP380B1, RpCYP4CH2, and RpCYP4C1) were significantly down-regulated following knockdown of RpGPCR41 in LC-R and BIF-R strains. Our results highlight the involvement of GPCR gene overexpression in the resistance of R. padi to pyrethroids, providing valuable insights into the mechanisms underlying aphid resistance and a potential target for aphid control.

KAT8 is upregulated and recruited to the promoter of Atg8 by FOXO to induce H4 acetylation for autophagy under 20-hydroxyecdysone regulation

Selective gene expression in cells in physiological or pathological conditions is important for the growth and development of organisms. Acetylation of histone H4 at K16 (H4K16ac) catalyzed by histone acetyltransferase 8 (KAT8) is known to promote gene transcription; however, the regulation of KAT8 transcription and the mechanism by which KAT8 acetylates H4K16ac to promote specific gene expression are unclear. Using the lepidopteran insect Helicoverpa armigera as a model, we reveal that the transcription factor FOXO promotes KAT8 expression and recruits KAT8 to the promoter region of autophagy-related gene 8 (Atg8) to increase H4 acetylation at that location, enabling Atg8 transcription under the steroid hormone 20-hydroxyecdysone (20E) regulation. H4K16ac levels are increased in the midgut during metamorphosis, which is consistent with the expression profiles of KAT8 and ATG8. Knockdown of Kat8 using RNA interference results in delayed pupation and repression of midgut autophagy and decreases H4K16ac levels. Overexpression of KAT8-GFP promotes autophagy and increases H4K16ac levels. FOXO, KAT8, and H4K16ac colocalized at the FOXO-binding region to promote Atg8 transcription under 20E regulation. Acetylated FOXO at K180 and K183 catalyzed by KAT8 promotes gene transcription for autophagy. 20E via FOXO promotes Kat8 transcription. Knockdown or overexpression of FOXO appeared to give similar results as knockdown or overexpression of KAT8. Therefore, FOXO upregulates KAT8 expression and recruits KAT8 to the promoter region of Atg8, where the KAT8 induces H4 acetylation to promote Atg8 transcription for autophagy under 20E regulation. This study reveals the mechanism that KAT8 promotes transcription of a specific gene.

Indomethacin and 20-hydroxyecdysone influence protein expression in a Spodoptera frugiperda nervous system cell line

Insecticide mode of action studies provide insights into how new insecticidal actives function and contribute to assessing safety to humans and nontarget organisms. Insect cell lines that express potential target sites can serve as valuable tools in this effort. In this paper, we report on the influence of two signaling molecules on protein expression in a nervous system cell line established from Spodoptera frugiperda (Bayer/BCIRL-SfNS2-0714-TR). We selected this line because we established it in our laboratory and we are experienced in using it. Cells were exposed to the insect developmental hormone (1 µg/mL 20-hydroxyecdysone, 20E) and/or a cyclooxygenase (COX) inhibitor (25 μM indomethacin, INDO; inhibits prostaglandin [PG] biosynthesis) for 24 h (Day 2), 72 h (Day 4), or 120 h (Day 6). We selected a PG biosynthesis inhibitor because PGs act in many aspects of insect biology, such as embryonic development, immunity, and protein phosphorylation. We selected the developmental hormone, 20E, because it also acts in fundamental aspects of insect biology. We identified specific proteins via in silico analysis. Changes in protein expression levels were determined using liquid chromatography-mass spectrometry (MS) + MS-MS. The largest number of changes in protein expression occurred on Day 2. The combination of 20E plus INDO led to 222 differentially expressed proteins, which documents the deep significance of PGs and 20E in insect biology. 20E and, separately, INDO led to changes in 30 proteins each (p value < 0.01; >2X or <0.5X-fold changes). We recorded changes in the expression of 9 or 12 proteins (20E), 10 or 6 proteins (INDO), and 21 or 20 proteins (20E + INDO) on D4 and D6, respectively. While the cell line was established from neuronal tissue, the differentially expressed proteins act in a variety of fundamental cell processes. In this paper, we moved beyond a list of proteins by providing detailed, Gene Ontology term analyses and enrichment, which offers an in-depth understanding of the influence of these treatments on the SfNS2 cells. Because proteins are active components of cell physiology in their roles as enzymes, receptors, elements of signaling transduction pathways, and cellular structures, changes in their expression levels under the influence of signaling molecules provide insights into their function in insect cell physiology.

Combined Computational-Biochemical Approach Offers an Accelerated Path to Membrane Protein Solubilization

Membrane proteins are difficult to isolate and purify due to their dependence on the surrounding lipid membrane for structural stability. Detergents are often used to solubilize these proteins, with this approach requiring a careful balance between protein solubilization and denaturation. Determining which detergent is most appropriate for a given protein has largely been done empirically through screening, which requires large amounts of membrane protein and associated resources. Here, we describe an alternative to conventional detergent screening using a computational modeling approach to identify the most likely candidate detergents for solubilizing a protein of interest. We demonstrate our approach using ghrelin O-acyltransferase (GOAT), a member of the membrane-bound O-acyltransferase family of integral membrane enzymes that has not been solubilized or purified in active form. A computationally derived GOAT structural model provides the only structural information required for this approach. Using computational analysis of detergent ability to penetrate phospholipid bilayers and stabilize the GOAT structure, a panel of common detergents were rank-ordered for their proposed ability to solubilize GOAT. The simulations were performed at all-atom resolution for a combined simulation time of 24 μs. Independently, we biologically screened these detergents for their solubilization of fluorescently tagged GOAT constructs. We found computational prediction of protein structural stabilization was the better predictor of detergent solubilization ability, but neither approach was effective for predicting detergents that would support GOAT enzymatic function. The current rapid expansion of membrane protein computational models lacking experimental structural information and our computational detergent screening approach can greatly improve the efficiency of membrane protein detergent solubilization, supporting downstream functional and structural studies.

The Jinggangmycin-induced Mthl2 gene regulates the development and stress resistance in Nilaparvata lugens Stål (Hemiptera: Delphacidae)

Methuselah (Mth) belongs to the GPCR family B, which regulates various biological processes and stress responses. The previous transcriptome data showed jinggangmycin (JGM)-induced Mthl2 expression. However, its detailed functional role remained unclear in brown planthopper, Nilaparvata lugens Stål. In adult N. lugens, the Mthl2 gene showed dominant expressions, notably in ovaries and fat body tissues. The 3rd instar nymphs treated with JGM increased starvation, oxidative stress, and high temperature (34 °C) tolerance of the adults. On the contrary, under dsMthl2 treatment, completely opposite phenotypes were observed. The lipid synthesis genes (DGAT1and PNPLA3) of both females and males treated with JGM in the nymphal stage were observed with high expressions, while the lipolysis of the Lipase 3 gene was observed with low expressions. The JGM increased triglyceride (TG) content, fat body droplet size, and the number of fat body droplets. The same treatment also increased the Glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) activities. An increase in the heat shock protein (HSP70 and HSP90) expression levels was also observed under JGM treatment but not dsMthl2. The current study demonstrated the influential role of the Mthl genes, particularly the Mthl2 gene, in modulating the growth and development and stress-responsiveness in N. lugens. Thus, providing a platform for future applied research programs controlling N. lugens population in rice fields.

Interaction of the AKT and β-catenin signalling pathways and the influence of photobiomodulation on cellular signalling proteins in diabetic wound healing

The induction of a cells destiny is a tightly controlled process that is regulated through communication between the matrix and cell signalling proteins. Cell signalling activates distinctive subsections of target genes, and different signalling pathways may be used repeatedly in different settings. A range of different signalling pathways are activated during the wound healing process, and dysregulated cellular signalling may lead to reduced cell function and the development of chronic wounds. Diabetic wounds are chronic and are characterised by the inability of skin cells to act in response to reparative inducements. Serine/threonine kinase, protein kinase B or AKT (PKB/AKT), is a central connection in cell signalling induced by growth factors, cytokines and other cellular inducements, and is one of the critical pathways that regulate cellular proliferation, survival, and quiescence. AKT interacts with a variety of other pathway proteins including glycogen synthase kinase 3 beta (GSK3β) and β-catenin. Novel methodologies based on comprehensive knowledge of activated signalling pathways and their interaction during normal or chronic wound healing can facilitate quicker and efficient diabetic wound healing. In this review, we focus on interaction of the AKT and β-catenin signalling pathways and the influence of photobiomodulation on cellular signalling proteins in diabetic wound healing.

Deciphering Molecular Mechanisms Governing the Reproductive Molt of Macrobrachium nipponense: A Transcriptome Analysis of Ovaries across Various Molting Stages

The relationship between molting and reproduction has received more attention in economically important crustacean decapods. Molting and reproduction are synergistic events in Macrobrachium nipponense, but the molecular regulatory mechanisms behind them are unclear. In the current study, we performed Illumina sequencing for the ovaries of M. nipponense during the molt cycle (pre-molting, Prm; mid-molting, Mm; and post-molting, Pom). A total of 66.57 Gb of transcriptome data were generated through sequencing, resulting in the identification of 105,149 unigenes whose alignment ratio with the reference genome exceeded 87.57%. Differentially expressed genes (DEGs) were annotated through the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases for gene classification and pathway analysis. A total of twenty-six molt-related DEGs were found, and their expression patterns were examined across various molting stages. The KEGG enrichment analysis revealed that the key pathways involved in regulating the molting process of M. nipponense primarily include the mTOR, insect hormone biosynthesis, TGF-beta, and Wnt signaling pathways. Our transcriptomic data suggest that these pathways crosstalk with each other to regulate the synthesis and degradation of ecdysone throughout the molt cycle. The current study has deepened our understanding of the molecular mechanisms of crustacean molting and will serve as a basis for future studies of crustaceans and other molting animals.

20-Hydroxyecdysone counteracts insulin to promote programmed cell death by modifying phosphoglycerate kinase 1

BACKGROUND

The regulation of glycolysis and autophagy during feeding and metamorphosis in holometabolous insects is a complex process that is not yet fully understood. Insulin regulates glycolysis during the larval feeding stage, allowing the insects to grow and live. However, during metamorphosis, 20-hydroxyecdysone (20E) takes over and regulates programmed cell death (PCD) in larval tissues, leading to degradation and ultimately enabling the insects to transform into adults. The precise mechanism through which these seemingly contradictory processes are coordinated remains unclear and requires further research. To understand the coordination of glycolysis and autophagy during development, we focused our investigation on the role of 20E and insulin in the regulation of phosphoglycerate kinase 1 (PGK1). We examined the glycolytic substrates and products, PGK1 glycolytic activity, and the posttranslational modification of PGK1 during the development of Helicoverpa armigera from feeding to metamorphosis.

RESULTS

Our findings suggest that the coordination of glycolysis and autophagy during holometabolous insect development is regulated by a balance between 20E and insulin signaling pathways. Glycolysis and PGK1 expression levels were decreased during metamorphosis under the regulation of 20E. Insulin promoted glycolysis and cell proliferation via PGK1 phosphorylation, while 20E dephosphorylated PGK1 via phosphatase and tensin homolog (PTEN) to repress glycolysis. The phosphorylation of PGK1 at Y194 by insulin and its subsequent promotion of glycolysis and cell proliferation were important for tissue growth and differentiation during the feeding stage. However, during metamorphosis, the acetylation of PGK1 by 20E was key in initiating PCD. Knockdown of phosphorylated PGK1 by RNA interference (RNAi) at the feeding stage led to glycolysis suppression and small pupae. Insulin via histone deacetylase 3 (HDAC3) deacetylated PGK1, whereas 20E via acetyltransferase arrest-defective protein 1 (ARD1) induced PGK1 acetylation at K386 to stimulate PCD. Knockdown of acetylated-PGK1 by RNAi at the metamorphic stages led to PCD repression and delayed pupation.

CONCLUSIONS

The posttranslational modification of PGK1 determines its functions in cell proliferation and PCD. Insulin and 20E counteractively regulate PGK1 phosphorylation and acetylation to give it dual functions in cell proliferation and PCD.

Can short-term data accurately model long-term environmental exposures? Investigating the multigenerational adaptation potential of Daphnia magna to environmental concentrations of organic ultraviolet filters

Organic ultraviolet filters (UVFs) are contaminants of concern, ubiquitously found in many aquatic environments due to their use in personal care products to protect against ultraviolet radiation. Research regarding the toxicity of UVFs such as avobenzone, octocrylene and oxybenzone indicate that these chemicals may pose a threat to invertebrate species; however, minimal long-term studies have been conducted to determine how these UVFs may affect continuously exposed populations. The present study modeled the effects of a 5-generation exposure of Daphnia magna to these UVFs at environmental concentrations. Avobenzone and octocrylene resulted in minor, transient decreases in reproduction and wet mass. Oxybenzone exposure resulted in > 40% mortality, 46% decreased reproduction, and 4-fold greater reproductive failure over the F0 and F1 generations; however, normal function was largely regained by the F2 generation. These results indicate that Daphnia are able to acclimate over long-term exposures to concentrations of 6.59 μg/L avobenzone, ∼0.6 μg/L octocrylene or 16.5 μg/L oxybenzone. This suggests that short-term studies indicating high toxicity may not accurately represent long-term outcomes in wild populations, adding additional complexity to risk assessment practices at a time when many regions are considering or implementing UVF bans in order to protect these most sensitive invertebrate species.

Functional characterization of putative ecdysone transporters in lepidopteran pests

The insect steroid hormone ecdysone plays a critical role in insect development. Several recent studies have shown that ecdysone enters cells through Organic Anion Transporting Polypeptides (OATPs) in insects such as flies and mosquitoes. However, the conservation of this mechanism across other arthropods and the role of this transporter in canonical ecdysone pathways are less well studied. Herein we functionally characterized the putative ecdysone importer (EcI) from two major agricultural moth pests: Helicoverpa armigera (cotton bollworm) and Spodoptera frugiperda (fall armyworm). Phylogenetic analysis of OATP transporters across the superphylum Ecdysozoa revealed that EcI likely appeared only at the root of the arthropod lineage. Partial disruption of EcI in S. frugiperda decreased embryo hatching rate and larval survival, suggesting that this gene is essential for development in vivo. Depletion and re-expression of EcI in the lepidoptera cell line RP-HzGUT-AW1(MG) demonstrated this protein's ability to control ecdysone mediated signaling in gene regulation, its role in ecdysone mediated cell death, and its sensitivity to rifampicin, a well-known organic anion transporter inhibitor. Overall, this work sheds light on ecdysone uptake mechanisms across insect species and broadens our knowledge of the physiological roles of OATPs in the transportation of endogenous substrates.

Allosteric Modulation of Muscarinic Receptors by Cholesterol, Neurosteroids and Neuroactive Steroids

Muscarinic acetylcholine receptors are membrane receptors involved in many physiological processes. Malfunction of muscarinic signaling is a cause of various internal diseases, as well as psychiatric and neurologic conditions. Cholesterol, neurosteroids, neuroactive steroids, and steroid hormones are molecules of steroid origin that, besides having well-known genomic effects, also modulate membrane proteins including muscarinic acetylcholine receptors. Here, we review current knowledge on the allosteric modulation of muscarinic receptors by these steroids. We give a perspective on the research on the non-genomic effects of steroidal compounds on muscarinic receptors and drug development, with an aim to ultimately exploit such knowledge.

Host–Pathogen Interactions between Metarhizium spp. and Locusts

The progress in research on the interactions between Metarhizium spp. and locusts has improved our understanding of the interactions between fungal infection and host immunity. A general network of immune responses has been constructed, and the pathways regulating fungal pathogenicity have also been explored in depth. However, there have been no systematic surveys of interaction between Metarhizium spp. and locusts. The pathogenesis of Metarhizium comprises conidial attachment, germination, appressorial formation, and colonization in the body cavity of the host locusts. Meanwhile, the locust resists fungal infection through humoral and cellular immunity. Here, we summarize the crucial pathways that regulate the pathogenesis of Metarhizium and host immune defense. Conidial hydrophobicity is mainly affected by the contents of hydrophobins and chitin. Appressorial formation is regulated by the pathways of MAPKs, cAMP/PKA, and Ca²⁺/calmodulin. Lipid droplets degradation and secreted enzymes contributed to fungal penetration. The humoral response of locust is coordinated by the Toll pathway and the ecdysone. The regulatory mechanism of hemocyte differentiation and migration is elusive. In addition, behavioral fever and density-dependent population immunity have an impact on the resistance of hosts against fungal infection. This review depicts a prospect to help us understand host–pathogen interactions and provides a foundation for the engineering of entomopathogenic fungi and the discovery of insecticidal targets to control insect pests.

MiR-3017b contributes to metamorphosis by targeting sarco/endoplasmic reticulum Ca2+ ATPase in Tribolium castaneum

In recent years, increasing numbers of microRNAs (miRNAs) have been reported to regulate insect metamorphosis. One thousand, one hundred fifty-four miRNAs have been previously identified from Tribolium castaneum by high-throughput sequencing; however, little is known about which miRNAs can participate in metamorphosis, leaving the role of miRNAs in regulating the underlying mechanism elusive. Here, we report the participation of miR-3017b in the metamorphosis of T. castaneum. Temporal profiles revealed that miR-3017b was highly expressed at the late larval stage, but significantly decreased at the early pupal stage. Overexpression of miR-3017b caused larval to pupal to adult metamorphosis arrested. Dual-luciferase reporter assay and miRNA-mRNA interaction assay illustrated that miR-3017b interacts with the coding sequence of sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) and suppresses its expression. Knockdown of SERCA caused metamorphosis arrested, similar to that observed in miR-3017b overexpression beetles. Further functional mechanism analyses revealed that 20-hydroxyecdysone application downregulates miR-3017b and up-regulates SERCA expression. The expression level of downstream genes in the 20E pathway was disrupted after overexpressing miR-3017 and the knockdown of SERCA. These results provided evidence miR-3017b-SERCA contributes to metamorphosis by regulating the 20E pathway in T. castaneum. It could advance our understanding of the coordination of 20E and miRNA regulation in insect metamorphosis.

Identification and Functional Analysis of G Protein-Coupled Receptors in 20-Hydroxyecdysone Signaling From the Helicoverpa armigera Genome

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors in animals and humans, which transmit various signals from the extracellular environment into cells. Studies have reported that several GPCRs transmit the same signal; however, the mechanism is unclear. In the present study, we identified all 122 classical GPCRs from the genome of Helicoverpa armigera, a lepidopteran pest species. Twenty-four GPCRs were identified as upregulated at the metamorphic stage by comparing the transcriptomes of the midgut at the metamorphic and feeding stages. Nine of them were confirmed to be upregulated at the metamorphic stage. RNA interference in larvae revealed the prolactin-releasing peptide receptor (PRRPR), smoothened (SMO), adipokinetic hormone receptor (AKHR), and 5-hydroxytryptamine receptor (HTR) are involved in steroid hormone 20-hydroxyecdysone (20E)-promoted pupation. Frizzled 7 (FZD7) is involved in growth, while tachykinin-like peptides receptor 86C (TKR86C) had no effect on growth and pupation. Via these GPCRs, 20E regulated the expression of different genes, respectively, including Pten (encoding phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase), FoxO (encoding forkhead box O), BrZ7 (encoding broad isoform Z7), Kr-h1 (encoding Krüppel homolog 1), Wnt (encoding Wingless/Integrated) and cMyc, with hormone receptor 3 (HHR3) as their common regulating target. PRRPR was identified as a new 20E cell membrane receptor using a binding assay. These data suggested that 20E, via different GPCRs, regulates different gene expression to integrate growth and development.

Diversity of Plant Sterols Metabolism: The Impact on Human Health, Sport, and Accumulation of Contaminating Sterols

The way of plant sterols transformation and their benefits for humans is still a question under the massive continuing revision. In fact, there are no receptors for binding with sterols in mammalians. However, possible biotransformation to steroids that can be catalyzed by gastro-intestinal microflora, microbial cells in prebiotics or cytochromes system were repeatedly reported. Some products of sterols metabolization are capable to imitate resident human steroids and compete with them for the binding with corresponding receptors, thus affecting endocrine balance and entire physiology condition. There are also tremendous reports about the natural origination of mammalian steroid hormones in plants and corresponding receptors for their binding. Some investigations and reports warn about anabolic effect of sterols, however, there are many researchers who are reluctant to believe in and have strong opposing arguments. We encounter plant sterols everywhere: in food, in pharmacy, in cosmetics, but still know little about their diverse properties and, hence, their exact impact on our life. Most of our knowledge is limited to their cholesterol-lowering influence and protective effect against cardiovascular disease. However, the world of plant sterols is significantly wider if we consider the thousands of publications released over the past 10 years.

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.