Cadmium and pyrene in the soil modify the properties of earthworm-mediated soil.

Earthworms are pivotal in soil ecosystems due to their crucial role in shaping soil characteristics through casts and burrow walls. Previous research has predominantly focused on the direct impact of soil pollution on live earthworms, overlooking the subsequent effects on earthworm-mediated soil, such as casts and burrow walls. Using 2D-terraria as incubation containers and the geophagous earthworm species Metaphire guillelmi, this study assessed the change in various properties of earthworm-mediated soil in both uncontaminated soils and Cd- and Pye-contaminated soils. Overall, both Cd and Pye overall improved the ammonium nitrogen (NH4+-N), Olsen's phosphorus (Olsen-P) levels, and invertase and catalase activities while decreasing catalase activities in earthworm-mediated soil. They also fluctuating affected the pH, soil organic matter (SOM) content, soil urease, alkaline phosphatase activities, and microbial functional genes in the cast and burrow walls. These results indicated that earthworms remained crucial "ecosystem engineers" even in polluted soil. Additionally, differences were observed in the responses of properties between casts and burrow walls, showing unequal contributions of transit-through-gut and burrowing processes to soil modification. Specifically, transit-through-gut was found to have a more significant influence on soil NH4+-N and Olsen-P content compared to burrowing behavior. Regarding the pattern of microbial functional genes in earthworm-associated compartments, results revealed that they differed significantly in casts from those in bulk soil and burrow walls under unpolluted conditions, with pollution-enhancing disparities among compartments. Furthermore, NH4+-N and Olsen-P content, urease, and catalase activities in burrow walls and/or casts were identified as potential biomarkers for soil pollution, exhibiting a clear dose-effect relationship. Developing such biomarkers could address ethical concerns related to conventional earthworm biomarkers that require sacrificing earthworms. This study provides insights into the consequences of soil pollution on earthworm-mediated soil components, highlighting the importance of considering the indirect effects of contaminants on soil ecosystems.

[Exploration of cancer biological characteristics in people with different five movements and six climates constitution based on pan-cancer Bulk RNA-Seq].

According to the theory of five movements and six climates, the innate constitution plays a crucial role in determining the underlyingpa thological mechanisms of diseases later in life. Previous studies have demonstrated a close association between the constitution, as defined by the theory of five movements and six climates, and the development of various types of tumors. Furt hermore,the tumorsubtype determined by the constitution has prognostic implications. This highlights the potential of utilizing the fivemovements and six climates theory to guide the implementation of precision medicine strategies in thefield of oncology. However, no resear ch has yet been conducted to investigate the use of this theory in guiding the development of tumor molecular classification and precisi onmedicine strategies. The objective of this research is to uncover the biological characteristics of each constitution within a pancanc ercohort and identify potential anti-tumor drugs that are applicable to patients with different constitutional types. By doing so, we aimto c ontribute to the establishment of a precision medicine strategy for tumors derived from the original concepts of traditional Chi nesemedicine(TCM). In this study, we obtainedpan-cancer Bulk RNA-Seq data from UCSC Xena, GWAS cohort data from the UKBiobank, and cis-eQTLs data from eQ TLGen and GTEx V8. We employed machine learning methods to screen for hub genes associated with each constitution. Subsequently, we utilized informatics tools to explore the biological characteristics of each constitut iondefined by the theory of five movements and six bioclimates. Further, potential anti-tumor drugs suitable for patients with differen tconstitutional types were identified through mendelian randomization, molecular docking, and drug-like prediction techniques. Withinthe pan-cancer cohort, significant differences were observed among different constitutions in terms of progression-free interval, biological f unctions, immune cell abundance, tumor drug sensitivity, and immunotherapy response. These findings suggest that the five movements and six climates theory can guide tumor molecular classification and the development of precision medicine strategies. Moreover,the biological characteristics inherent to each constitution partially shed light on the scientific implications of Chinese medicinetheories, offering a fresh perspective towards clinical cancer treatment. Through molecular docking and drug-like prediction, several po tential anti-tumor drugs such as 17-beta-estradiol, serotonin, trans-resveratrol, and linoleic acid were identified. Overall, the util izationof multi-omics approaches pro vides a powerful tool to unravel the scientific foundations of TCM theories. The elucidation of themu lti-omics features associated witheach constitution in tumors serves as the basis for applying the five movements and six climates theoryto tumor molecular classification and the development of precision medicine strategies.

Genetic and Epigenetic Landscape for Drug Development in Polycystic Ovary Syndrome.

The treatment of polycystic ovary syndrome (PCOS) faces challenges as all known treatments are merely symptomatic. The US Food and Drug Administration has not approved any drug specifically for treating PCOS. As the significance of genetics and epigenetics rises in drug development, their pivotal insights have greatly enhanced the efficacy and success of drug target discovery and validation, offering promise for guiding the advancement of PCOS treatments. In this context, we outline the genetic and epigenetic advancement in PCOS, which provide novel insights into the pathogenesis of this complex disease. We also delve into the prospective method for harnessing genetic and epigenetic strategies to identify potential drug targets and ensure target safety. Additionally, we shed light on the preliminary evidence and distinctive challenges associated with gene and epigenetic therapies in the context of PCOS.

Inetetamab combined with tegafur as second-line treatment for human epidermal growth factor receptor-2-positive gastric cancer: A case report.

BACKGROUND: Human epidermal growth factor receptor-2 (HER-2) plays a vital role in tumor cell proliferation and metastasis. However, the prognosis of HER2-positive gastric cancer is poor. Inetetamab, a novel anti-HER2 targeting drug independently developed in China, exhibits more potent antibody-dependent cell-mediated cytotoxicity than trastuzumab, which is administered as the first-line treatment for HER2-positive gastric cancer in combination with chemotherapy. In this case, the efficacy and safety of inetetamab combined with tegafur was investigated as a second-line treatment for HER2-positive gastric cancer. CASE SUMMARY: A 52-year-old male patient with HER2-positive gastric cancer presented with abdominal distension, poor appetite, and fatigue two years after receiving six cycles of oxaliplatin combined with tegafur as first-line treatment after surgery, followed by tegafur monotherapy for six months. The patient was diagnosed with postoperative recurrence of gastric adenocarcinoma. He received 17 cycles of a combination of inetetamab, an innovative domestically developed anti-HER2 monoclonal antibody, and tegafur chemotherapy as the second-line treatment (inetetamab 200 mg on day 1, every 3 wk combined with tegafur twice daily on days 1-14, every 3 wk). Evaluation of the efficacy of the second-line treatment revealed that the patient achieved a stable condition and progression-free survival of 17 months. He tolerated the treatment well without exhibiting any grade 3-4 adverse events. CONCLUSION: Inetetamab combined with chemotherapy for the treatment of metastatic HER2-positive gastric cancer demonstrates significant survival benefits and acceptable safety.

Temporal trends and risk factors of perioperative cardiac events in patients over 80 years old with coronary artery disease undergoing noncardiac surgery: a high-volume single-center experience, 2014-2022.

BACKGROUND: Temporal trends and risk factors of perioperative cardiac events (PCEs) in patients over 80 years old with coronary artery disease (CAD) undergoing noncardiac surgery are still unclear. METHODS: We retrospectively reviewed 1478 patients over 80 years old, with known CAD undergoing selective noncardiac surgery in a single center (2014-2022). Patients were divided into three equal time groups based on the discharge date (2014-2016, 2017-2019, and 2020-2022), with 367, 473, and 638 patients in Groups 1-3, respectively. Perioperative clinical variables were extracted from the electronic medical records database. The primary outcome was the occurrence of PCEs intraoperatively or during hospitalization postoperatively, defined as any of the following events: myocardial infarction, heart failure, nonfatal cardiac arrest, and death. RESULTS: PCEs occurred in 180 (12.2%) patients. Eight independent risk factors were associated with PCEs, including four clinical factors (body mass index < 22 kg/m2, history of myocardial infarction, history of heart failure, and general anesthesia) and four preoperative laboratory results (hemoglobin < 110 g/L, albumin < 40 g/L, creatinine > 120 µmol/L, and potassium <3.6 mmol/L). Significant rising trends were seen over the 9-year study period in the incidence of PCEs and independent risk factors including history of myocardial infarction, history of heart failure, general anesthesia, preoperative hemoglobin < 110 g/L, preoperative albumin < 40 g/L, and preoperative creatinine > 120 µmol/L (P for trend <0.05). CONCLUSION: The incidence and independent risk factors of PCEs in patients over 80 years old with CAD undergoing noncardiac surgery showed significant rising trends over the last 9-year period.

Effects of cadmium and pyrene on earthworm-associated bacterial communities: Unveiling new perspectives for soil pollution management.

Earthworms are considered to be excellent bioindicators of soil pollution. In recent years, there has been increasing interest in examining the effects of soil pollution on earthworm-associated microbiomes, with a particular focus on the gut microbiomes. However, relatively little effort has been invested in comprehensively investigating other microbiomes associated with earthworms and their responses to soil pollution. To fill this gap, we systematically studied the effects of Cd, pyrene, and combined pollution on the bacterial community in different vermicompartments, i.e., burrow wall, gut, and cast, in both epigeic Eisenia fetida and anecic Metaphire guillelmi, using a 2D-terraria incubator and high-throughput sequencing techniques. The results showed that bacterial alpha diversity followed the order of burrow wall > cast > gut, and this did not vary with soil pollution or earthworm ecotypes. Moreover, the dominant phyla in the vermicompartments were similar across different pollution treatments. Principal coordinate analysis (PCoA) revealed that the bacterial communities in different vermicompartments and ecotypes of earthworm were separated from each other, whereas they were grouped together in polluted treatments and unpolluted conditions. These results imply that even in polluted soil, vermicompartment and earthworm ecotypes remain the most significant factors affecting earthworm-associated microbiomes. However, the impacts of soil pollution on the bacterial composition in each vermicompartment were still evident. A comprehensive analysis revealed that the gut bacterial communities are more sensitive to soil contamination than casts and burrow wall in different ecotypes. Additionally, linear discriminant analysis of effect size (LefSe) identified several bacteria in Gemmatimonadota, the Firmicutes phylum in the burrow walls, and Patescibacteria (phyla) in the gut as potential biomarkers for pyrene contamination in soil. This research provides a comprehensive understanding of the effects of soil pollution on earthworm-associated microbiomes, thereby enhancing our understanding of earthworm ecotoxicology and soil pollution management.

Neuron stem cell NLRP6 sustains hippocampal neurogenesis to resist stress-induced depression.

Neurogenesis decline in hippocampal dentate gyrus (DG) participates in stress-induced depressive-like behaviors, but the underlying mechanism remains poorly understood. Here, we observed low-expression of NOD-like receptor family pyrin domain containing 6 (NLRP6) in hippocampus of stress-stimulated mice, being consistent with high corticosterone level. NLRP6 was found to be abundantly expressed in neural stem cells (NSCs) of DG. Both Nlrp6 knockout (Nlrp6-/-) and NSC-conditional Nlrp6 knockout (Nlrp6CKO) mice were susceptible to stress, being more likely to develop depressive-like behaviors. Interestingly, NLRP6 was required for NSC proliferation in sustaining hippocampal neurogenesis and reinforcing stress resilience during growing up. Nlrp6 deficiency promoted esophageal cancer-related gene 4 (ECRG4) expression and caused mitochondrial dysfunction. Corticosterone as a stress factor significantly down-regulated NLRP6 expression, damaged mitochondrial function and suppressed cell proliferation in NSCs, which were blocked by Nlrp6 overexpression. ECRG4 knockdown reversed corticosterone-induced NSC mitochondrial function and cell proliferation disorders. Pioglitazone, a well-known clinical drug, up-regulated NLRP6 expression to inhibit ECRG4 expression in its protection against corticosterone-induced NSC mitochondrial dysfunction and proliferation restriction. In conclusion, this study demonstrates that NLRP6 is essential to maintain mitochondrial homeostasis and proliferation in NSCs, and identifies NLRP6 as a promising therapeutic target for hippocampal neurogenesis decline linked to depression.

Transferrin Receptor Is Necessary for Proper Oligodendrocyte Iron Homeostasis and Development.

To test the hypothesis that the transferrin (Tf) cycle has unique importance for oligodendrocyte development and function, we disrupted the expression of the Tf receptor (Tfr) gene in oligodendrocyte progenitor cells (OPCs) on mice of either sex using the Cre/lox system. This ablation results in the elimination of iron incorporation via the Tf cycle but leaves other Tf functions intact. Mice lacking Tfr, specifically in NG2 or Sox10-positive OPCs, developed a hypomyelination phenotype. Both OPC differentiation and myelination were affected, and Tfr deletion resulted in impaired OPC iron absorption. Specifically, the brains of Tfr cKO animals presented a reduction in the quantity of myelinated axons, as well as fewer mature oligodendrocytes. In contrast, the ablation of Tfr in adult mice affected neither mature oligodendrocytes nor myelin synthesis. RNA-seq analysis performed in Tfr cKO OPCs revealed misregulated genes involved in OPC maturation, myelination, and mitochondrial activity. Tfr deletion in cortical OPCs also disrupted the activity of the mTORC1 signaling pathway, epigenetic mechanisms critical for gene transcription and the expression of structural mitochondrial genes. RNA-seq studies were additionally conducted in OPCs in which iron storage was disrupted by deleting the ferritin heavy chain. These OPCs display abnormal regulation of genes associated with iron transport, antioxidant activity, and mitochondrial activity. Thus, our results indicate that the Tf cycle is central for iron homeostasis in OPCs during postnatal development and suggest that both iron uptake via Tfr and iron storage in ferritin are critical for energy production, mitochondrial activity, and maturation of postnatal OPCs.SIGNIFICANCE STATEMENT By knocking-out transferrin receptor (Tfr) specifically in oligodendrocyte progenitor cells (OPCs), we have established that iron incorporation via the Tf cycle is key for OPC iron homeostasis and for the normal function of these cells during the postnatal development of the CNS. Moreover, RNA-seq analysis indicated that both Tfr iron uptake and ferritin iron storage are critical for proper OPC mitochondrial activity, energy production, and maturation.

Quantitative analysis of contrast-enhanced ultrasound in neoadjuvant treatment of locally advanced rectal cancer: a retrospective study.

Purpose: To explore the clinical value of contrast-enhanced ultrasound (CEUS) quantitative analysis in the evaluation and prognosis of neoadjuvant chemoradiotherapy for locally advanced rectal cancer (LARC). Methods: Eighty-three consecutive patients undergoing neoadjuvant chemoradiotherapy and total mesorectal excision for LARC were retrospectively included. According to pathological results, patients were categorized into complete or incomplete response groups. Differences in ultrasonic parameters, pathological results, and clinical data between groups were evaluated. The cutoff point for a complete response as determined by quantitative analysis of CEUS was assessed using a receiver operating characteristic curve; additionally, overall survival (OS) and progression-free survival (PFS) were analyzed. Results: Of the 83 patients, 12 (14.5%) achieved a complete response and 71 (85.5%) did not. There were significant between-group differences in carcinoembryonic antigen (CEA) levels, differentiation degree, proportion of tumor occupying the lumen, anterior-posterior and superior-inferior diameters of the lesion, and intensity of enhancement (P<0.05). CEUS quantitative analysis showed significant between-group differences in peak intensity (PI) and area under the curve (AUC) values (P<0.05). The OS and PFS of patients with high PI, high AUC value, and poorly differentiated cancer were significantly worse than those with low PI, low AUC values, and moderately to highly differentiated cancer (P<0.05). High CEA levels (hazard ratio: 1.02, 95% confidence interval: 1.01-1.04; P=0.002) and low differentiation (2.72, 1.12-6.62; P=0.028) were independent risk factors for PFS and OS. Conclusions: CEUS can predict the response to neoadjuvant treatment in patients with LARC. CEUS quantitative analysis is helpful for clinical prognosis.

Advances in clinical applications of kisspeptin-GnRH pathway in female reproduction.

BACKGROUND: Kisspeptin is the leading upstream regulator of pulsatile and surge Gonadotrophin-Releasing Hormone secretion (GnRH) in the hypothalamus, which acts as the key governor of the hypothalamic-pituitary-ovary axis. MAIN TEXT: Exogenous kisspeptin or its receptor agonist can stimulate GnRH release and subsequent physiological gonadotropin secretion in humans. Based on the role of kisspeptin in the hypothalamus, a broad application of kisspeptin and its receptor agonist has been recently uncovered in humans, including central control of ovulation, oocyte maturation (particularly in women at a high risk of ovarian hyperstimulation syndrome), test for GnRH neuronal function, and gatekeepers of puberty onset. In addition, the kisspeptin analogs, such as TAK-448, showed promising agonistic activity in healthy women as well as in women with hypothalamic amenorrhoea or polycystic ovary syndrome. CONCLUSION: More clinical trials should focus on the therapeutic effect of kisspeptin, its receptor agonist and antagonist in women with reproductive disorders, such as hypothalamic amenorrhoea, polycystic ovary syndrome, and endometriosis.

Mendelian randomization analyses for PCOS: evidence, opportunities, and challenges.

Identifying etiological risk factors is significant for preventing and treating patients with polycystic ovary syndrome (PCOS). Through genetic variation, Mendelian randomization (MR) assesses causal associations between PCOS risk and related exposure factors. This emerging technology has provided evidence of causal associations of anti-Müllerian hormone (AMH) levels, sex hormone-binding globulin (SHBG) levels, menopause age, adiposity, insulin resistance (IR), depression, breast cancer, ovarian cancer, obsessive-compulsive disorder (OCD), and forced vital capacity (FVC) with PCOS, while lacking associations of type 2 diabetes mellitus (T2DM), coronary heart disease (CHD), stroke, anxiety disorder (AD), schizophrenia (SCZ), bipolar disorder (BIP), and offspring birth weight with PCOS. In this review, we briefly introduce the concept and methodology of MR in terms of the opportunities and challenges in this field based on recent results obtained from MR analyses involving PCOS.

Dysregulated circulating microRNA-126 in chronic obstructive pulmonary disease: linkage with acute exacerbation risk, severity degree, and inflammatory cytokines.

BACKGROUND: MicroRNA-126 (miR-126) is engaged in respiratory diseases via regulating airway tissue injury and pulmonary inflammation, while its relation with chronic obstructive pulmonary disease (COPD) is not reported. The study aimed to evaluate the value of miR-126 for estimating COPD acute exacerbation risk and its relation to disease severity and inflammatory cytokines in COPD patients. METHODS: This study was a case-control study. Seventy acute exacerbation COPD (AECOPD) patients, 70 stable COPD (SCOPD) patients, and 70 healthy controls (HCs) were consecutively recruited. Plasma miR-126 expression was detected by reverse transcription quantitative polymerase chain reaction. Plasma tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and interleukin-17 (IL-17) in COPD patients were further determined by enzyme-linked immunosorbent assay. RESULTS: MiR-126 was higher in AECOPD patients compared to SCOPD patients and HCs (both Padj  < 0.001). Receiver operating characteristic curves revealed miR-126 distinguished AECOPD patients from SCOPD patients (area under curve (AUC): 0.805, 95%CI: 0.733-0.877) and HCs (AUC: 0.884, 95%CI: 0.829-0.939) and also distinguished SCOPD from HCs (AUC = 0.656, 95%CI: 0.566-0.747). MiR-126 positively related to GOLD stage in both AECOPD patients (p < 0.001) and SCOPD patients (p < 0.001). Furthermore, miR-126 positively linked with TNF-α (p < 0.001), IL-1ß (p = 0.002), IL-6 (p = 0.009), and IL-17 (p < 0.001) levels in AECOPD patients; but miR-126 only positively related to TNF-α and IL-17 levels (all p < 0.050), instead of IL-1ß or IL-6 level (all p > 0.050) in SCOPD patients and HCs. CONCLUSION: Dysregulated circulating miR-126 not only relates to COPD susceptibility and its acute exacerbation risk but also links with disease severity and inflammatory cytokines in COPD patients.

Xa7, a Small Orphan Gene Harboring Promoter Trap for AvrXa7, Leads to the Durable Resistance to Xanthomonas oryzae Pv. oryzae.

BACKGROUND: The rice (Oryza sativa) gene Xa7 has been hypothesized to be a typical executor resistance gene against Xanthomonas oryzae pv. oryzae (Xoo), and has conferred durable resistance in the field for decades. Its identity and the molecular mechanisms underlying this resistance remain elusive. RESULTS: Here, we filled in gaps of genome in Xa7 mapping locus via BAC library construction, revealing the presence of a 100-kb non-collinear sequence in the line IRBB7 compared with Nipponbare reference genomes. Complementary transformation with sequentially overlapping subclones of the BACs demonstrated that Xa7 is an orphan gene, encoding a small novel protein distinct from any other resistance proteins reported. A 27-bp effector binding element (EBE) in the Xa7 promoter is essential for AvrXa7-inducing expression model. XA7 is anchored in the endoplasmic reticulum membrane and triggers programmed cell death in rice and tobacco (Nicotiana benthamiana). The Xa7 gene is absent in most cultivars, landraces, and wild rice accessions, but highly homologs of XA7 were identified in Leersia perrieri, the nearest outgroup of the genus Oryza. CONCLUSIONS: Xa7 acts as a trap to perceive AvrXa7 via EBEAvrXa7 in its promoter, leading to the initiation of resistant reaction. Since EBEAvrXa7 is ubiquitous in promoter of rice susceptible gene SWEET14, the elevated expression of which is conducive to the proliferation of Xoo, that lends a great benefit for the Xoo strains retaining AvrXa7. As a result, varieties harboring Xa7 would show more durable resistance in the field. Xa7 alleles analysis suggests that the discovery of new resistance genes could be extended beyond wild rice, to include wild grasses such as Leersia species.

Long noncoding RNA lncARSR promotes hepatic lipogenesis via Akt/SREBP-1c pathway and contributes to the pathogenesis of nonalcoholic steatohepatitis.

Non-alcoholic fatty liver disease and steatohepatitis (NAFLD and NASH) account for the majority of liver disease in industrialized countries. However, the pathogenesis still unclear. Long non-coding RNAs (lncRNAs) has been reported to be involved in various pathophysiological processes. Here, we reported a novel role of lncARSR in hepatic lipogenesis in NAFLD. The expression of lncARSR was induced both in NAFLD patients and mouse model, as well as in hepatocytes treated with fatty acid. Moreover, overexpression of lncARSR enhanced while knockdown of lncARSR ameliorated hepatic lipid accumulation in vivo and in vitro. Furthermore, the expression of genes related to fatty acid synthesis and oxidation increased with lncARSR overexpression in vivo. Mechanistically, we identified that lncARSR regulated hepatic lipogenesis via upregulating SREBP-1c, the key regulatory molecule involved in lipogenesis. Knockdown of SREBP-1c by shRNA blocked the effect of lncARSR on lipogenesis. Furthermore, we demonstrated that lncARSR regulated SREBP-1c expression by PI3K/Akt pathway. In conclusion, our data indicated that lncARSR potentially contributes to the hepatic steatosis in NAFLD, which may be a new therapeutic target against NAFLD.

EXPRESS: F-actin links Epac-PKC signaling to purinergic P2X3 receptors sensitization in dorsal root ganglia following inflammation.

Sensitization of purinergic P2X3 receptors (P2X3Rs) contributes to the production of exaggerated nociceptive responses following inflammatory injury. We showed previously that prostaglandin E2 (PGE2) potentiates P2X3R-mediated ATP currents in dorsal root ganglion neurons isolated from both control and complete Freund's adjuvant-induced inflamed rats. PGE2 potentiation of ATP currents depends only on PKA signaling in control neurons, but it depends on both PKA and PKC signaling in inflamed neurons. We further found that inflammation evokes an increase in exchange proteins directly activated by cAMP (Epacs) in dorsal root ganglions. This increase promotes the activation of PKC to produce a much enhanced PGE2 effect on ATP currents and to elicit Epac-dependent flinch nocifensive behavioral responses in complete Freund's adjuvant rats. The link between Epac-PKC signaling and P2X3R sensitization remains unexplored. Here, we show that the activation of Epacs promotes the expression of phosphorylated PKC and leads to an increase in the cytoskeleton, F-actin, expression at the cell perimeter. Depolymerization of F-actin blocks PGE2-enhanced ATP currents and inhibits P2X3R-mediated nocifensive responses after inflammation. Thus, F-actin is dynamically involved in the Epac-PKC-dependent P2X3R sensitization. Furthermore, Epacs induce a PKC-dependent increase in the membrane expression of P2X3Rs. This increase is abolished by F-actin depolymerization, suggesting that F-actin mediates Epac-PKC signaling of P2X3R membrane expression. Thus, after inflammation, an Epac-PKC dependent increase in F-actin in dorsal root ganglion neurons enhances the membrane expression of P2X3Rs to bring about sensitization of P2X3Rs and abnormal pain behaviors.

Abscisic acid, H2O2 and nitric oxide interactions mediated cold-induced S-adenosylmethionine synthetase in Medicago sativa subsp. falcata that confers cold tolerance through up-regulating polyamine oxidation.

S-adenosylmethionine synthetase (SAMS) is the key enzyme catalysing the formation of S-adenosylmethionine (SAM), a precursor of polyamines and ethylene. To investigate the potential role of SAMS in cold tolerance, we isolated MfSAMS1 from the cold-tolerant germplasm Medicago sativa subsp. falcata and analysed the association of SAM-derived polyamines with cold tolerance. The expression of MfSAMS1 in leaves was greatly induced by cold, abscisic acid (ABA), H2O2 and nitric oxide (NO). Our data revealed that ABA, H2O2 and NO interactions mediated the cold-induced MfSAMS1 expression and cold acclimation in falcata. SAM, putrescine, spermidine and spermine levels, ethylene production and polyamine oxidation were sequentially altered in response to cold, indicating that SAMS-derived SAM is preferentially used in polyamine synthesis and homeostasis during cold acclimation. Antioxidant enzyme activities were also induced in response to cold and showed correlation with polyamine oxidation. Overexpression of MfSAMS1 in tobacco resulted in elevated SAM levels, but polyamine levels and ethylene production in the transgenic plants were not significantly changed. Compared to the wild type, transgenic plants had increased levels of apoplastic H2O2, higher transcript levels of genes involved in polyamine synthesis and oxidation, and higher activities of polyamine oxidation and antioxidant enzymes. The results showed that overexpression of MfSAMS1 promoted polyamine synthesis and oxidation, which in turn improved H2 O2 -induced antioxidant protection, as a result enhanced tolerance to freezing and chilling stress in transgenic plants. This is the first report demonstrating that SAMS plays an important role in plant tolerance to cold via up-regulating polyamine oxidation.

Hydrogen peroxide and nitric oxide mediated cold- and dehydration-induced myo-inositol phosphate synthase that confers multiple resistances to abiotic stresses.

myo-Inositol phosphate synthase (MIPS) is the key enzyme of myo-inositol synthesis, which is a central molecule required for cell metabolism and plant growth as a precursor to a large variety of compounds. A full-length fragment of MfMIPS1 cDNA was cloned from Medicago falcata that is more cold-tolerant than Medicago sativa. While MfMIPS1 transcript was induced in response to cold, dehydration and salt stress, MIPS transcript and myo-inositol were maintained longer and at a higher level in M. falcata than in M. sativa during cold acclimation at 5 °C. MfMIPS1 transcript was induced by hydrogen peroxide (H(2) O(2)) and nitric oxide (NO), but was not responsive to abscisic acid (ABA). Pharmacological experiments revealed that H(2) O(2) and NO are involved in the regulation of MfMIPS1 expression by cold and dehydration, but not by salt. Overexpression of MfMIPS1 in tobacco increased the MIPS activity and levels of myo-inositol, galactinol and raffinose, resulting in enhanced resistance to chilling, drought and salt stresses in transgenic tobacco plants. It is suggested that MfMIPS1 is induced by diverse environmental factors and confers resistance to various abiotic stresses.

Neuronal soma-satellite glial cell interactions in sensory ganglia and the participation of purinergic receptors.

It has been known for some time that the somata of neurons in sensory ganglia respond to electrical or chemical stimulation and release transmitters in a Ca2+-dependent manner. The function of the somatic release has not been well delineated. A unique characteristic of the ganglia is that each neuronal soma is tightly enwrapped by satellite glial cells (SGCs). The somatic membrane of a sensory neuron rarely makes synaptic contact with another neuron. As a result, the influence of somatic release on the activity of adjacent neurons is likely to be indirect and/or slow. Recent studies of neuron-SGC interactions have demonstrated that ATP released from the somata of dorsal root ganglion neurons activates SGCs. They in turn exert complex excitatory and inhibitory modulation of neuronal activity. Thus, SGCs are actively involved in the processing of afferent information. In this review, we summarize our understanding of bidirectional communication between neuronal somata and SGCs in sensory ganglia and its possible role in afferent signaling under normal and injurious conditions. The participation of purinergic receptors is emphasized because of their dominant roles in the communication.

A critical role of the cAMP sensor Epac in switching protein kinase signalling in prostaglandin E2-induced potentiation of P2X3 receptor currents in inflamed rats.

Sensitization of purinergic P2X receptors is one of the mechanisms responsible for exaggerated pain responses to inflammatory injuries. Prostaglandin E2 (PGE2), produced by inflamed tissues, is known to contribute to abnormal pain states. In a previous study, we showed that PGE2 increases fast inactivating ATP currents that are mediated by homomeric P2X3 receptors in dorsal root ganglion (DRG) neurons isolated from normal rats. Protein kinase A (PKA) is the signalling pathway used by PGE2. Little is known about the action of PGE2 on ATP currents after inflammation, although the information is crucial for understanding the mechanisms underlying inflammation-induced sensitization of P2X receptors. We therefore studied the effects of PGE2 on P2X3 receptor-mediated ATP currents in DRG neurons dissociated from complete Freund's adjuvant (CFA)-induced inflamed rats. We found that PGE2 produces a large increase in ATP currents. PKCepsilon, in addition to PKA, becomes involved in the modulatory action of PGE2. Thus, PGE2 signalling switches from a solely PKA-dependent pathway under normal conditions to both PKA- and PKC-dependent pathways after inflammation. Studying the mechanisms underlying the switch, we demonstrated that cAMP-responsive guanine nucleotide exchange factor 1 (Epac1) is up-regulated after inflammation. The Epac agonist CPT-OMe mimics the potentiating effect of PGE2 and occludes the PKC-mediated PGE2 action on ATP currents. These results suggest that Epac plays a critical role in P2X3 sensitization by activation of de novo PKC-dependent signalling of PGE2 after inflammation and would be a useful therapeutic target for pain therapies.

Prostaglandin E2 potentiation of P2X3 receptor mediated currents in dorsal root ganglion neurons.

Prostaglandin E2 (PGE2) is a well-known inflammatory mediator that enhances the excitability of DRG neurons. Homomeric P2X3 and heteromeric P2X2/3 receptors are abundantly expressed in dorsal root ganglia (DRG) neurons and participate in the transmission of nociceptive signals. The interaction between PGE2 and P2X3 receptors has not been well delineated. We studied the actions of PGE2 on ATP-activated currents in dissociated DRG neurons under voltage-clamp conditions. PGE2 had no effects on P2X2/3 receptor-mediated responses, but significantly potentiated fast-inactivating ATP currents mediated by homomeric P2X3 receptors. PGE2 exerted its action by activating EP3 receptors. To study the mechanism underlying the action of PGE2, we found that the adenylyl cyclase activator, forskolin and the membrane-permeable cAMP analogue, 8-Br-cAMP increased ATP currents, mimicking the effect of PGE2. In addition, forskolin occluded the enhancement produced by PGE2. The protein kinase A (PKA) inhibitors, H89 and PKA-I blocked the PGE2 effect. In contrast, the PKC inhibitor, bisindolymaleimide (Bis) did not change the potentiating action of PGE2. We further showed that PGE2 enhanced alpha,beta-meATP-induced allodynia and hyperalgesia and the enhancement was blocked by H89. These observations suggest that PGE2 binds to EP3 receptors, resulting in the activation of cAMP/PKA signaling pathway and leading to an enhancement of P2X3 homomeric receptor-mediated ATP responses in DRG neurons.