Publications by authors named "Dihui Xu"

10 Publications

  • Page 1 of 1

Silencing of METTL3 effectively hinders invasion and metastasis of prostate cancer cells.

Theranostics 2021 11;11(16):7640-7657. Epub 2021 Jun 11.

Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing 210093, China.

: Since primary prostate cancer (PCa) can advance to the life-threatening metastatic PCa, exploring the molecular mechanisms underlying PCa metastasis is crucial for developing the novel targeted preventive strategies for decreasing the mortality of PCa. RNA N-methyladenosine (mA) is an emerging regulatory mechanism for gene expression and its specific roles in PCa progression remains elusive. Western blotting, quantitative real-time PCR and immunohistochemical analyses were used to detect target gene expression in PCa cells and prostate tissues from patients. RNA immunoprecipitation was conducted to analyze the specific binding of mRNA to the target protein. Migration and invasion assays were used to assess the migratory capacities of cancer cells. The correlation between target gene expression and survival rate of PCa patients was analyzed based the TCGA database. We found that total RNA N-methyladenosine (mA) modification levels were markedly upregulated in human PCa tissues due to increased expression of methyltransferase like 3 (METTL3). Further studies revealed that the migratory and invasive capacities of PCa cells were markedly suppressed upon METTL3 knockdown. Mechanistically, METTL3 mediates mA modification of USP4 mRNA at A2696, and mA reader protein YTHDF2 binds to and induces degradation of mRNA by recruiting RNA-binding protein HNRNPD to the mRNA. Decrease of USP4 fails to remove the ubiquitin group from ELAVL1 protein, resulting in a reduction of ELAVL1 protein. Lastly, downregulation of ELAVL1 in turn increases ARHGDIA expression, promoting migration and invasion of PCa cells. Our findings highlight the role of METTL3 in modulating invasion and metastasis of PCa cells, providing insight into promising therapeutic strategies for hindering PCa progressing to deadly metastases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7150/thno.61178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8315076PMC
June 2021

Chronic MC-LR exposure promoted Aβ and p-tau accumulation via regulating Akt/GSK-3β signal pathway.

Sci Total Environ 2021 Jun 29;794:148732. Epub 2021 Jun 29.

Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing 210093, China. Electronic address:

It has been reported that microcystin-leucine-arginine (MC-LR) can enter into the brain and demonstrate neurotoxicity resulting in learning and memory deficits. While, there is still a lack of clear understanding of the related molecular mechanisms. In this study, we observed β-amyloid (Aβ) accumulation and tau hyperphosphorylation (p-tau) at sites of Ser396 and Thr205 in mouse hippocampus and cortex, Alzheimer's disease (AD) like changes, after chronic exposure to MC-LR at different concentrations (1, 7.5, 15 and 30 μg/L) for 180 days. The hallmarks of AD are characterized by senile plaques and neurofibrillary tangles (NFT), with associated loss of neurons, resulting in cognitive impairment and dementia. Similarly, the production of Aβ and tau hyperphosphorylation was also detected in HT-22 cells treated with MC-LR. In addition, MC-LR promoted increased expressions of BACE1 and PS1, but reduced mRNA expressions of ADAM family members both in vivo and in vitro, promoting the Aβ production. Moreover, we identified Akt/GSK-3β signal pathway mediated the Aβ and p-tau accumulation, bringing about Alzheimer's disease-like changes. Furthermore, microglial cells were activated in those mice exposed to MC-LR. Inflammatory cytokines were also found being activated to release in vitro. In conclusion, this study could provide a clue for MC-LR-induced neurotoxicity, which gave insights into the environmental risks of Alzheimer's disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2021.148732DOI Listing
June 2021

Ultrafiltration strategy combined with nanoLC-MS/MS based proteomics for monitoring potential residual proteins in TCMIs.

J Chromatogr B Analyt Technol Biomed Life Sci 2021 Jul 30;1178:122818. Epub 2021 May 30.

Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China. Electronic address:

Traditional Chinese medicine injections (TCMIs) containing complex constituents frequently cause unpredictable adverse reactions. The residual heterologous proteins in TCMIs may be one kind of the sensitized constituents. However, few methods were developed to identify and monitor the residual proteins of TCMIs in industry. Here, we described a method combining the advantages of ultrafiltration and mass spectrometry-based proteomics for monitoring the potential residual proteins in Re Du Ning injection (RDNI) intermediates and preparations. We identified and quantified both de novo peptides and the proteins matched against databases of three raw plants by using PEAKS software. Interesting, we found there was a significant decrease of peptides and proteins in No. 3-5 of RDNI intermediates and some even disappeared. Besides, we found this method could greatly reduce the interference of contaminants in proteomics experiments. The rapid and accurate method proposed in this paper could be used for monitoring potential residual proteins in TCMIs to guarantee their quality and safety.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jchromb.2021.122818DOI Listing
July 2021

Anti-inflammatory and analgesic actions of bufotenine through inhibiting lipid metabolism pathway.

Biomed Pharmacother 2021 Aug 28;140:111749. Epub 2021 May 28.

Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, China.

Inflammation is a primary defense and immune response. However, under pathological conditions, the inflammation processes always become uncontrolled and lead to chronic diseases. Bufotenine, as a natural component from toad venom, showed great potential for development as a novel anti-inflammation and analgesia agent. This study aimed to investigate the therapeutic effects of bufotenine against inflammation and pain on animal models with a focus on lipid metabolism. In pharmacological studies, bufotenine significantly inhibited the swelling rates on formalin-induced paw edema model, and increased paw withdrawal mechanical thresholds (PWMTs) in von Frey test and thermal pain thresholds (TPTs) in hot-plate test. High-sensitivity lipidomics analysis revealed the effects might be related to the down-regulation of inflammatory mediators from cyclooxygenase (COX), lipoxygenase (LOX), cytochrome P450 (CYP450), linoleic acid (LA), docosahexaenoic acid (DHA) and other pathways. The activities might result from the binding of bufotenine and its receptors, including sigma-1 receptor and 5-Hydroxytryptamine receptor 3A, thus regulating lipid metabolism pathway. The research provided a systemic evidence for the actions and mechanism of bufotenine. It suggested that the natural compound might be a potential candidate for reducing inflammatory pain disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biopha.2021.111749DOI Listing
August 2021

Systematic toxicity evaluation of polystyrene nanoplastics on mice and molecular mechanism investigation about their internalization into Caco-2 cells.

J Hazard Mater 2021 09 13;417:126092. Epub 2021 May 13.

Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing 210093, China. Electronic address:

There is a growing concern regarding the toxic effects of nanoplastics (NPs) on aquatic and marine organism, while relatively few studies about their toxicity evaluation on mammals are conducted. In the present study, we observed accumulation of polystyrene NPs (PS NPs) in mice spleen, lung, kidney, small intestine, large intestine, testis, and brain after oral exposure to PS NPs (~100 nm, 10 mg/mL, 100 μL) for 28 days, and NPs were identified to induce cell apoptosis, inflammation, and structure disorder in these tissues. We also found that PS NPs could bring about hematological system injury and lipid metabolism disorder. Further in vitro studies identified that PS NPs could be absorbed by the intestinal epithelial Caco-2 cells by macropinocytosis and clathrin-mediated endocytosis, and induced disruption of tight junction between Caco-2 cells. Moreover, we found that it was easier for PS-NH and PS-COOH to enter into Caco-2 cells, which may be associated with observed stronger toxicity of PS-NH and PS-COOH NPs. In summary, this study demonstrated that NPs exposure brings about toxic effects to mice. This study could provide new insights regarding the distribution of NPs in humans, and helps us to evaluate the potential physiological risks of NPs to human beings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2021.126092DOI Listing
September 2021

Identification, expression and enzyme activity of the group III sPLA s in Cyprinus carpio L.

J Fish Biol 2021 Jul 26;99(1):25-36. Epub 2021 May 26.

Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China.

Five group III secreted phospholipase (pla2g3s) homologous genes located on different linkage groups were identified from common carp (Cyprinus carpio), which we named Ccpla2g3a1, Ccpla2g3a2, Ccpla2g3b, Ccpla2g3c1 and Ccpla2g3c2. The five genes encode 530, 525, 461, 752 and 753 amino acids, respectively. Sequence analysis showed that the Ccpla2g3as contain seven exons and the others contain four exons. Synteny analysis of fish pla2g3s indicated that pla2g3a and pla2g3b were from the same ancestor gene, and Ccpla2g3a1, Ccpla2g3a2, Ccpla2g3c1 and Ccpla2g3c2 were from the specific genome duplication of common carp. Due to the significant variation of the pla2g3bs from common carp and zebrafish (Danio rerio), they formed a separate group in the phylogenetic tree. The tissue distributions of Ccpla2g3s coincided with their expression profiles during the embryo stages. The expression levels of Ccpla2g3as and Ccpla2g3cs were low at the embryo stages, and they were abundant in the liver and brain, respectively, whereas the expression of Ccpla2g3b was high at 0.5 h after fertilization and in the ovary. We obtained three soluble recombinant proteins of the bee venom-like PLA2 (BVLP) from Ccpla2g3 and evaluated their PLA enzyme properties. The optimum pHs of MBP-a1-BVLP, MBP-b-BVLP and MBP-c1-BVLP were 7.5, 7.0 and 8.0, respectively, and specific activities were 7.68 ± 0.66, 4.155 ± 0.158 and 1.93 ± 0.05 U μmol , respectively. The K for Ca of MBP-b-BVLP was the lowest (2.6 μM), whereas the values for both MBP-a1-BVLP and MBP-c1-BVLP were about 15 μM. The K values of three proteins ranged from 31.9 to 41.91 μM.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jfb.14694DOI Listing
July 2021

Evaluation of analgesic and anti-inflammatory actions of indolealkylamines from toad venom in mice using lipidomics and molecular docking.

J Ethnopharmacol 2021 Apr 13;269:113677. Epub 2020 Dec 13.

Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, And Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China. Electronic address:

Ethnopharmacological Relevance: Toad venom is one of widely used traditional Chinese medicines due to its analgesic and anti-inflammatory activities. However, hydrophilic alkaloids from toad venom, which may have certain pharmacological activities, have not been systematic studied.

Aim Of The Study: The aim of the study was to identify the indolealkylamines (IAAs) from toad venom and investigate the analgesic and anti-inflammatory actions.

Materials And Methods: The alkaloids were extracted and identified by high-resolution mass spectrometry. The analgesic abilities were determined using hot-plate test, formalin test and von Frey test. High-sensitivity lipidomics was used to investigate the regulatory function of IAAs on inflammatory eicosanoids. Besides, network pharmacology and molecular docking were used to demonstrate the candidate targets of IAAs.

Results: 22 constituents have been characterized by high performance liquid chromatography (HPLC)-Triple TOF 5600, including six specific IAAs (serotonin, N-methyl serotonin, bufotenine, bufotenidine, bufothionine and dehydrobufotenine). Pharmacological studies showed that the IAAs from toad venom exerted significant analgesic activities at doses of 5, 15 and 45 mg/kg in vivo. Moreover, lipids analysis revealed IAAs might down-regulate inflammatory mediators from COX, LOX, DHA and LA pathways in formalin models, thus showing anti-inflammatory effect. The potent pharmacological function might because of the binding of IAAs and protein targets, such as sigma-1 receptor.

Conclusion: The studies provided a systemic evidence for the analgesic and anti-inflammatory activities of IAAs from toad venom. It suggested that IAAs might be a potential candidate to reduce inflammatory pain disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jep.2020.113677DOI Listing
April 2021

Microcystin-leucine-arginine induces apical ectoplasmic specialization disassembly.

Chemosphere 2021 Feb 25;264(Pt 1):128440. Epub 2020 Sep 25.

Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China. Electronic address:

Microcystin-leucine-arginine (MC-LR) has been identified to be a hazardous material to cause hepatotoxicity. In this study, mice were exposed to MC-LR dissolved in drinking water at doses of 1, 10, 20 and 30 μg/L for 90 and 180 days, respectively. We validated MC-LR accelerated spermatid exfoliation and caused large vacuoles in testes, reducing sperm count and increasing percentage of morphologically abnormal sperm. Furthermore, we found MC-LR induced the apical ectoplasmic specialization (ES) disassembly by disrupting F-actin organization. Further studies identified that downregulation of Palladin, the actin crosslinking protein, might be associated with disassembly of the apical ES in mice testis following MC-LR exposure. We also confirmed that MC-LR disrupted the interaction between Palladin and other actin-related proteins and thus impeded the F-actin organization. Additionally, we found that autophagy initiated by AMPK/ULK1 signaling pathway mediated the degradation of Palladin in Sertoli cells challenged with MC-LR. Following exposure to MC-LR, reduced PP2A activity and upregulated expression of LKB1 and CAMKK2 could activate AMPK. In conclusion, these results revealed MC-LR induced the degradation of Palladin via AMPK/ULK1-mediated autophagy, which might result in the apical ES disorder and spermatid exfoliation from spermatogenic epithelium. Our work may provide a new perspective to understand MC-LR-induced male infertility.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2020.128440DOI Listing
February 2021

mA mRNA methylation regulates testosterone synthesis through modulating autophagy in Leydig cells.

Autophagy 2021 02 31;17(2):457-475. Epub 2020 Jan 31.

Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China.

Macroautophagy/autophagy is indispensable for testosterone synthesis in Leydig cells (LCs), and here we report a negative association between mA modification and autophagy in LCs during testosterone synthesis. A gradual decrease of METTL14 (methyltransferase like 14) and an increase of ALKBH5 (alkB homolog 5, RNA demethylase) were observed in LCs during their differentiation from stem LCs to adult LCs. These events led to reduced mRNA methylation levels of N-methyladenosine (mA) and enhanced autophagy in LCs. Similar regulation of METTL14, ALKBH5, and mA was also observed in LCs upon treatment with human chorionic gonadotropin (HsCG). Mechanistically, mA modification promoted translation of PPM1A (protein phosphatase 1A, magnesium dependent, alpha isoform), a negative AMP-activated protein kinase (AMPK) regulator, but decreased expression of CAMKK2 (calcium/calmodulin-dependent protein kinase kinase 2, beta), a positive AMPK regulator, by reducing its RNA stability. Thus, mA modification resulted in reduced AMPK activity and subsequent autophagy inhibition. We further demonstrated that ALKBH5 upregulation by HsCG was dependent on enhanced binding of the transcriptional factor CEBPB (CCAAT/enhancer binding protein [C/EBP], beta) and the TFEB (transcription factor EB) to its gene promoter. Moreover, HsCG treatment decreased METTL14 by reducing its stability. Collectively, this study highlights a vital role of mA RNA methylation in the modulation of testosterone synthesis in LCs, providing insight into novel therapeutic strategies by exploiting mA RNA methylation as targets for treating azoospermatism and oligospermatism patients with reduction in serum testosterone. 3-MA: 3-methyladenine; ACTB: Actin, beta; ALKBH5: alkB homolog 5, RNA demethylase; AMPK: AMP-activated protein kinase; BafA1: bafilomycin A CAMKK2: calcium/calmodulin-dependent protein kinase kinase 2, beta; CEBPB: CCAAT/enhancer-binding protein (C/EBP), beta; ChIP: chromatin immunoprecipitation; FTO: fat mass and obesity associated; HsCG: human chorionic gonadotropin; HSD3B: 3β-hydroxysteroid dehydrogenase; LCs: Leydig cells; mA: N-methyladenosine; METTL14: methyltransferase like 14; METTL3: methyltransferase like 3; MTOR: mechanistic target of rapamycin kinase; PPM1A: protein phosphatase 1A, magnesium dependent, alpha isoform; PRKAA: 5'-AMP-activated protein kinase catalytic subunit alpha; SQSTM1: sequestosome 1; STK11/LKB1: serine/threonine kinase 11; TFEB: transcription factor EB; ULK1: unc-51-like kinase 1; WTAP: Wilms tumor 1-associating protein; YTHDF: YTH N6-methyladenosine RNA binding protein.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/15548627.2020.1720431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8007139PMC
February 2021

Mechanistic Study of Copper-Catalyzed C-H Hydroxylation/C-S Coupling by ESI-HR MS and DFT Calculations.

Molecules 2017 Nov 6;22(11). Epub 2017 Nov 6.

Department of Biology and Environment, Jiyang College of Zhejiang A&F University, Shaoxing 311800, China.

The reaction mechanism of Cu-catalyzed C-H hydroxylation/C-S coupling was studied using electrospray ionization high resolution mass spectrometry (ESI-HR MS) and density functional theory calculations (DFT). Notably, a series of Cu and Cu complexes were observed as key intermediates and identified using ESI-HR MS. Furthermore, a catalyst cycle involving proton abstraction/oxidative addition/reductive elimination was proposed. This study is important and valuable with respect to C-H functionalization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/molecules22111912DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6150210PMC
November 2017
-->