7361. Mechanisms to Repair Stalled Topoisomerase II-DNA Covalent Complexes.
DNA topoisomerases regulate the topological state of DNA, relaxing DNA supercoils and resolving catenanes and knots that result from biologic processes, such as transcription and replication. DNA topoisomerase II (TOP2) enzymes achieve this by binding DNA and introducing an enzyme-bridged DNA double-strand break (DSB) where each protomer of the dimeric enzyme is covalently attached to the 5' end of the cleaved DNA via an active site tyrosine phosphodiester linkage. The enzyme then passes a second DNA duplex through the DNA break, before religation and release of the enzyme. However, this activity is potentially hazardous to the cell, as failure to complete religation leads to persistent TOP2 protein-DNA covalent complexes, which are cytotoxic. Indeed, this property of topoisomerase has been exploited in cancer therapy in the form of topoisomerase poisons which block the religation stage of the reaction cycle, leading to an accumulation of topoisomerase-DNA adducts. A number of parallel cellular processes have been identified that lead to removal of these covalent TOP2-DNA complexes, facilitating repair of the resulting protein-free DSB by standard DNA repair pathways. These pathways presumably arose to repair spontaneous stalled or poisoned TOP2-DNA complexes, but understanding their mechanisms also has implications for cancer therapy, particularly resistance to anti-cancer TOP2 poisons and the genotoxic side effects of these drugs. Here, we review recent progress in the understanding of the processing of TOP2 DNA covalent complexes, the basic components and mechanisms, as well as the additional layer of complexity posed by the post-translational modifications that modulate these pathways. SIGNIFICANCE STATEMENT: Multiple pathways have been reported for removal and repair of TOP2-DNA covalent complexes to ensure the timely and efficient repair of TOP2-DNA covalent adducts to protect the genome. Post-translational modifications, such as ubiquitination and SUMOylation, are involved in the regulation of TOP2-DNA complex repair. Small molecule inhibitors of these post-translational modifications may help to improve outcomes of TOP2 poison chemotherapy, for example by increasing TOP2 poison cytotoxicity and reducing genotoxicity, but this remains to be determined.
7362. Repressing MYC by targeting BET synergizes with selective inhibition of PI3Kα against B cell lymphoma.
作者: Zi-Qi Chen.;Zhe-Rui Cao.;Yi Wang.;Xi Zhang.;Lan Xu.;Yu-Xiang Wang.;Yi Chen.;Chun-Hao Yang.;Jian Ding.;Ling-Hua Meng.
来源: Cancer Lett. 2022年524卷206-218页
Phosphatidylinositol 3-kinase (PI3K) δ-specific inhibitors have been approved for the therapy of certain types of B cell lymphoma (BCL). However, their clinical use is limited by the substantial toxicity and lack of efficacy in other types of BCL. Emerging evidence indicates that PI3Kα plays important roles in the progression of B cell lymphoma. In this study, we revealed that PI3Kα was important for the PI3K signaling and proliferation in BCL cells. A novel clinical PI3Kα-selective inhibitor CYH33 possessed superior activity against BCL compared to the marketed PI3Kα-selective inhibitor Alpelisib and PI3Kδ-selective inhibitor Idelalisib. Though CYH33 was able to inhibit PI3K/AKT signaling in tested BCL cells, differential activity against proliferation was observed. Transcriptome profiling revealed that CYH33 down-regulated "MYC-targets" gene set in sensitive but not resistant cells. CYH33 inhibited c-MYC transcription in sensitive cells, which was attributed to a decrease in acetylated H3 bound to the promoter and super-enhancer region of c-MYC. Accordingly, CYH33 treatment resulted in phosphorylation and proteasomal degradation of the histone acetyltransferase p300. An unbiased screening with drugs approved or in clinical trials for the therapy of BCL identified that the clinical BET (Bromodomain and Extra Terminal domain) inhibitor OTX015 significantly potentiated the activity of CYH33 against BCL in vitro and in vivo, which was associated with enhanced inhibition on c-MYC expression and induction of cell cycle arrest and apoptosis. Our findings provide the rationale of combined CYH33 with BET inhibitors for the therapy of B cell lymphoma.
7363. Arjunolic acid from Cyclocarya paliurus ameliorates diabetic retinopathy through AMPK/mTOR/HO-1 regulated autophagy pathway.
作者: Xuan-Xuan Zhang.;Ya-Li Ji.;Li-Ping Zhu.;Zi-Han Wang.;Chang-Qian Fang.;Cui-Hua Jiang.;Ke Pan.;Jian Zhang.;Zhi-Qi Yin.
来源: J Ethnopharmacol. 2022年284卷114772页
Cyclocarya paliurus (CP) is a traditional Chinese herb and possesses a variety of biological activities including anti-hyperglycemia, anti-hyperlipidemia, antioxidant and anti-inflammation. Arjunolic acid (AA) is an abundant and bioactive ingredient in CP that shows significant protection against many metabolic diseases such as diabetic complication. Diabetic retinopathy (DR) is a serious complication of diabetes and may lead to vision loss. However, the protective effects and underlying mechanisms of AA against DR is not still understood.
7364. Epimedii Folium and Curculiginis Rhizoma ameliorate lipopolysaccharides-induced cognitive impairment by regulating the TREM2 signaling pathway.
作者: Kun Shi.;Lvyi Chen.;Linlin Chen.;Aihua Tan.;Guangjing Xie.;Qinghua Long.;Funan Ning.;Zhou Lan.;Ping Wang.
来源: J Ethnopharmacol. 2022年284卷114766页
Neuroinflammation induced by microglia is closely related to a variety of neurodegenerative diseases including Alzheimer's disease (AD). Previous study has found that aqueous extract of Epimedii Folium and Curculiginis Rhizoma (EX) had anti-inflammatory effect on AD by activating the NLRP3 inflammasome and inhibiting NF-κB/MAPK pathway. However, whether the anti-neuroinflammatory effect of EX is related to microglia or not remains unclear.
7365. Venlafaxine-induced adrenergic signaling stimulates Leydig cells steroidogenesis via Nur77 overexpression: A possible role of EGF.
作者: Fabiane de Santi.;Flávia L Beltrame.;Beatriz M Rodrigues.;Natália F Scaramele.;Flávia L Lopes.;Paulo S Cerri.;Estela Sasso-Cerri.
来源: Life Sci. 2022年289卷120069页
Venlafaxine, a norepinephrine and serotonin reuptake inhibitor, impairs rat sperm parameters, spermatogenesis and causes high intratesticular estrogen and testosterone levels, indicating that Leydig cells (LCs) may be a venlafaxine target. We evaluated the effect of venlafaxine treatment on rat LCs, focusing on adrenergic signaling, EGF immunoexpression and steroidogenesis. Germ cells mitotic/meiotic activity and UCHL1 levels were also evaluated in the seminiferous epithelium. Eighteen adult male rats received 30 mg/kg of venlafaxine (n = 9) or distilled water (n = 9). The seminiferous tubules, epithelium and LCs nuclear areas were measured, and the immunoexpression of Ki-67, UCHL1, StAR, EGF, c-Kit and 17β-HSD was evaluated. UCHL1, StAR and EGF protein levels and Adra1a, Nur77 and Ndrg2 expression were analyzed. Malondialdehyde (MDA) and nitrite testicular levels, and serum estrogen and testosterone levels were measured. Venlafaxine induced LCs hypertrophy and Ndrg2 upregulation in parallel to increased number of Ki-67, c-Kit- and 17β-HSD-positive interstitial cells, indicating that this antidepressant stimulates LCs lineage proliferation and differentiation. Upregulation of Adra1a and Nur77 could explain the high levels of StAR and testosterone levels, as well as aromatization. Enhanced EGF immunoexpression in LCs suggests that this growth fact is involved in adrenergically-induced steroidogenesis, likely via upregulation of Nur77. Slight tubular atrophy and weak Ki-67 immunoexpression in germ cells, in association with high UCHL1 levels, indicate that spermatogenesis is likely impaired by this enzyme under supraphysiological estrogen levels. These data corroborate the unchanged MDA and nitrite levels. Therefore, venlafaxine stimulates LCs steroidogenesis via adrenergic signaling, and EGF may be involved in this process.
7366. Induction of IL-6Rα by ATF3 enhances IL-6 mediated sorafenib and regorafenib resistance in hepatocellular carcinoma.
作者: Zichan Dai.;Xiaohan Wang.;Rangxin Peng.;Binghui Zhang.;Qi Han.;Jie Lin.;Jichuang Wang.;Junjin Lin.;Mingting Jiang.;Hekun Liu.;Tae Ho Lee.;Kun Ping Lu.;Min Zheng.
来源: Cancer Lett. 2022年524卷161-171页
Sorafenib and its derivative regorafenib are the first- and second-line targeted drugs for advanced HCC, respectively. Although both drugs improve overall survival, drug resistance remains the major barrier to their full efficacy. Thus, strategies to enhance sorafenib and regorafenib efficacy against HCC are solely needed. Interleukin-6 receptor alpha (IL-6Rα) is the receptor of IL-6, a multi-functional cytokine, which plays key roles in liver-regeneration, inflammation and development of hepatocellular carcinoma (HCC). Here we show the expression of IL-6Rα was induced in response to sorafenib. Depletion of IL-6Rα abolished IL-6 induced STAT3 phosphorylation at 705th tyrosine and tumor growth of HCC cells under sorafenib treatment. Mechanistically, activating transcription factor 3 (ATF3) was induced in response to sorafenib and subsequently bound to the promoter of IL-6Rα, leading to its transcriptional activation. Depletion of ATF3 or its upstream transcription factor, ATF4, attenuated IL-6Rα induction and IL-6 mediated sorafenib resistance. The ATF4-ATF3-IL-6Rα cascade is also activated by regorafenib. Furthermore, blockade of IL-6Rα with the FDA approved IL-6Rα antibody drug, Sarilumab, drastically attenuated both sorafenib and regorafenib resistance in patient-derived xenograft (PDX) tumors, where human IL-6 could be detected by a novel in situ hybridization technique, named RNAscope. Together, our data reveal that ATF3-mediated IL-6Rα up-regulation promotes both sorafenib and regorafenib resistance in HCC, and targeting IL-6Rα represents a novel therapeutic strategy to enhance sorafenib/regorafenib efficacy for advanced HCC treatment.
7367. Selenomethionine alleviated Ochratoxin A induced pyroptosis and renal fibrotic factors expressions in MDCK cells.
作者: Xinru Mao.;Hu Li.;Lei Ge.;Shuiping Liu.;Lili Hou.;Dongmei Yue.;Heng Du.;Cuiling Pan.;Fang Gan.;Yunhuan Liu.;Kehe Huang.;Xingxiang Chen.
来源: J Biochem Mol Toxicol. 2022年36卷1期e22933页
Ochratoxin A (OTA) is universally known to induce nephrotoxicity via inducing oxidative stress and apoptosis, inhibiting protein synthesis and activating autophagy. Our previous studies have proved that OTA induces nephrotoxicity in vitro and in vivo by adjusting the NOD-like receptor protein 3 (NLRP3) inflammasome activation and caspase-1-dependent pyroptosis. Based on these findings, we further investigated the protective role of selenomethionine (SeMet) on OTA-caused nephrotoxicity using the Madin-Darby canine kidney (MDCK) epithelial cells as an in vitro model, proposing to offer a new way for remedying OTA-induced nephrotoxicity by nutritional manipulation. We measured the cell vitality, lactate dehydrogenase (LDH) activity and the expression of renal fibrotic genes, NLRP3 inflammasome and pyroptosis related genes. MTT and LDH results indicated that SeMet supplementation significantly mitigated 2.0 μg/ml OTA-induced cytotoxicity in MDCK cells (p < 0.05). Meanwhile, SeMet alleviated OTA induced increase of reactive oxygen species in MDCK cells. Then, the expressions of α-SMA, Vimentin, and TGF-β were detected both in mRNA and protein levels. The results indicated 8 μM SeMet supplementation could significantly downregulate the expression of OTA-induced renal fibrosis-related genes (p < 0.05). In addition, the upregulation of OTA-induced NLRP3 inflammasome and pyroptosis downstream genes was also significantly inhibited by 8 μM of SeMet (p < 0.05). In summary, SeMet could alleviate OTA-induced renal fibrotic genes expression and reduce NLRP3-caspase-1-dependent pyroptosis. Therefore, SeMet supplementation may become an effective approach for preserving animals from renal injury exposed to OTA.
7368. Role of NRF2 cascade in determining the differential response of cervical cancer cells to anticancer drugs: an in vitro study.
作者: Pushkal Sinduvadi Ramesh.;Sharanya Raja.;Shwethambari Harave Udayakumar.;Shruthi Chandrashekar.;Suma M Nataraj.;Devananda Devegowda.
来源: Mol Biol Rep. 2022年49卷1期109-119页
Cervical cancers are usually treatable if detected in early stages by a combination of therapies. However, the prognosis of cervical cancer patients with metastasis remains unfavorable due to the fact that most of the cervical carcinomas are either resistant to anticancer drugs or show signs of relapse after initial treatment. Therefore, it is important to control the chemoresistance as it is the key to develop effective treatment options for cervical cancer.
7369. Echinodorus macrophyllus: Hydroxycinnamoyl derivatives reduces neutrophil migration through modulation of cytokines, chemokines, and prostaglandin in the air-pouch model.
作者: Girlaine Pereira da Silva.;Daniele Corrêa Fernandes.;Mariana Vieira Vigliano.;Fabiana Araújo Pinto.;Eduardo Nunes da Fonseca.;Shirley Vânia Moura Santos.;Paulo Roberto Marques.;Carlos Roberto Machado Gayer.;Leosvaldo Salazar Marques Velozo.;Cleverton Kleiton Freitas de Lima.;Ana Luisa Palhares de Miranda.;Maria da Graça Justo.;Kátia Costa de Carvalho Sabino.;Marsen Garcia Pinto Coelho.
来源: J Ethnopharmacol. 2022年284卷114757页
In Brazil, Echinodorus macrophyllus (Alismataceae), popularly known as chapéu-de-couro, is used to treat inflammatory diseases. Previous studies have shown a significant decrease in the acute inflammation for the aqueous extract of E. macrophyllus (AEEm) and its ethanolic fraction (Fr20).
7370. KDM1A inhibition augments the efficacy of rapamycin for the treatment of endometrial cancer.
作者: Prabhakar Pitta Venkata.;Yihong Chen.;Salvador Alejo.;Yi He.;Bridgitte E Palacios.;Ilanna Loeffel.;Junhao Liu.;Uday P Pratap.;Gabrielle Gray.;Sureshkumar Mulampurath Achuthan Pillai.;Yi Zou.;Zhao Lai.;Takayoshi Suzuki.;Suryavathi Viswanadhapalli.;Srinath Palakurthi.;Rajeshwar R Tekmal.;Ratna K Vadlamudi.;Edward Kost.;Gangadhara R Sareddy.
来源: Cancer Lett. 2022年524卷219-231页
Endometrial cancer (EC) often exhibit aberrant activation of PI3K/Akt/mTOR signaling and targeted therapies using mTOR inhibitors showed limited success. The epigenetic modifier, lysine-specific histone demethylase-1A (KDM1A/LSD1) is overexpressed in EC, however, the mechanistic and therapeutic implications of KDM1A in EC are poorly understood. Here, using 119 FDA-approved drugs screen, we identified that KDM1A inhibition is highly synergistic with mTOR inhibitors. Combination therapy of KDM1A and mTOR inhibitors potently reduced the cell viability, survival, and migration of EC cells. Mechanistic studies demonstrated that KDM1A inhibition attenuated the activation of mTOR signaling cascade and abolished rapamycin induced feedback activation of Akt. RNA-seq analysis identified that KDM1A inhibition downregulated the expression of genes involved in rapamycin induced activation of Akt, including the mTORC2 complex. Chromatin immunoprecipitation experiments confirmed KDM1A recruitment to the promoter regions of mTORC2 complex genes and that KDM1A inhibition promoted enrichment of repressive H3K9me2 marks at their promoters. Combination therapy of KDM1A inhibitor and rapamycin reduced the tumor growth in EC xenograft and patient derived xenograft models in vivo and patient derived tumor explants ex vivo. Importantly, in silico analysis of TCGA EC patients data sets revealed that KDM1A expression positively correlated with the levels of PI3K/Akt/mTOR genes. Collectively, our results provide compelling evidence that KDM1A inhibition potentiates the activity of mTOR inhibitors by attenuating the feedback activation of Akt survival signaling. Furthermore, the use of concurrent KDM1A and mTOR inhibitors may be an attractive targeted therapy for EC patients.
7371. Maternal caffeine intake and DNA methylation in newborn cord blood.
作者: Kristen J Polinski.;Alexandra Purdue-Smithe.;Sonia L Robinson.;Sifang Kathy Zhao.;Karen C Schliep.;Robert M Silver.;Weihua Guan.;Enrique F Schisterman.;Sunni L Mumford.;Edwina H Yeung.
来源: Am J Clin Nutr. 2022年115卷2期482-491页
Epigenetic mechanisms may underlie associations between maternal caffeine consumption and adverse childhood metabolic outcomes. However, limited studies have examined neonate DNA methylation (DNAm) patterns in the context of preconception or prenatal exposure to caffeine metabolites.
7372. P90 ribosomal S6 kinase confers cancer cell survival by mediating checkpoint kinase 1 degradation in response to glucose stress.
作者: Ying Ma.;Danrui Cui.;Linchen Wang.;Yue Wang.;Fei Yang.;Hui Pan.;Longyuan Gong.;Minrun Zhang.;Xiufang Xiong.;Yongchao Zhao.
来源: Cancer Sci. 2022年113卷1期132-144页
In solid tumors, cancer cells have devised multiple approaches to survival and proliferate in response to glucose starvation that is often observed in solid tumor microenvironments. However, the precise mechanisms are far less known. Herein, we report that glucose deprivation activates 90-kDa ribosomal S6 kinase (p90 RSK), a highly conserved Ser/Thr kinase, and activated p90 RSK promotes cancer cell survival. Mechanistically, activated p90 RSK by glucose deprivation phosphorylates checkpoint kinase 1 (CHK1), a key transducer in checkpoint signaling pathways, at Ser280 and triggers CHK1 ubiquitination mediated by SCFβ-TrCP ubiquitin ligase and proteasomal degradation, subsequently suppressing cancer cell apoptosis induced by glucose deprivation. Importantly, we identified an inverse correlation between p90 RSK activity and CHK1 levels within the solid tumor mass, with lower levels of CHK1 and higher activity of p90 RSK in the center of the tumor where low glucose concentrations are often observed. Thus, our study indicates that p90 RSK promotes CHK1 phosphorylation at Ser280 and its subsequent degradation, which allows cancer cells to escape from checkpoint signals under the stress of glucose deprivation, leading to cell survival and thus contributing to tumorigenesis.
7373. The androgen receptor-lncRNASAT1-AKT-p15 axis mediates androgen-induced cellular senescence in prostate cancer cells.
作者: Kimia Mirzakhani.;Julia Kallenbach.;Seyed Mohammad Mahdi Rasa.;Federico Ribaudo.;Martin Ungelenk.;Marzieh Ehsani.;Wenrong Gong.;Nikolaus Gassler.;Mirjam Leeder.;Marc-Oliver Grimm.;Francesco Neri.;Aria Baniahmad.
来源: Oncogene. 2022年41卷7期943-959页
The bipolar androgen therapy (BAT) to treat prostate cancer (PCa) includes cycles of supraphysiological androgen levels (SAL) under androgen-deprivation therapy (ADT). We showed previously that SAL induces cellular senescence in androgen-sensitive PCa cells and in ex vivo-treated patient PCa tumor samples. Here, we analyzed the underlying molecular pathway and reveal that SAL induces cellular senescence in both, castration-sensitive (CSPC) LNCaP and castration-resistant PCa (CRPC) C4-2 cells through the cell cycle inhibitor p15INK4b and increased phosphorylation of AKT. Treatment with the AKT inhibitor (AKTi) potently inhibited SAL-induced expression of p15INK4b and cellular senescence in both cell lines. Proximity-ligation assays (PLA) combined with high-resolution laser-scanning microscopy indicate that SAL promotes interaction of endogenous androgen receptor (AR) with AKT in the cytoplasm as well as in the nucleus detectable after three days. Transcriptome sequencing (RNA-seq) comparing the SAL-induced transcriptomes of LNCaP with C4-2 cells as well as with AKTi-treated cell transcriptomes revealed landscapes for cell senescence. Interestingly, one of the identified genes is the lncRNASAT1. SAL treatment of native patient tumor samples ex vivo upregulates lncRNASAT1. In PCa tumor tissues, lncRNASAT1 is downregulated compared with nontumor tissues of the same patients. Knockdown indicates that the lncRNASAT1 is crucial for SAL-induced cancer-cell senescence as an upstream factor for pAKT and for p15INK4b. Further, knockdown of lncRNASAT1 enhances cell proliferation by SAL, suggesting that lncRNASAT1 serves as a tumor suppressor at SAL. Interestingly, immunoprecipitation of AR detected lncRNASAT1 as an AR-interacting partner that regulates AR target-gene expression. Similarly, RNA-ChIP experiments revealed the interaction of AR with lncRNASAT1 on chromatin. Thus, we identified a novel AR-lncRNASAT1-AKT-p15INK4b signaling axis to mediate SAL-induced cellular senescence.
7374. TGF-β/YB-1/Atg7 axis promotes the proliferation of hepatic progenitor cells and liver fibrogenesis.
作者: Yuecheng Guo.;Jumo Zhu.;Xianjun Xu.;Bo Shen.;Zhenyang Shen.;Binghang Li.;Fei Li.;Tianyi Gu.;Xiaobo Cai.;Hui Dong.;Lungen Lu.
来源: Biochim Biophys Acta Mol Basis Dis. 2022年1868卷1期166290页
Hepatic fibrosis is characterized by excessive extracellular matrix deposition and ductular reactions, manifested as the expansion of hepatic progenitor cells (HPCs). We previously reported that the Y-box binding protein 1 (YB-1) in HPCs is involved in chronic liver injury. In this study, we constructed YB-1f/f Foxl1-Cre mice and investigated the role of YB-1 in HPC expansion in murine choline-deficient, ethionine-supplemented (CDE), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) models. Liver injury and fibrosis were measured using hematoxylin and eosin (HE), Masson, and Sirius Red staining. HPC proliferation was detected using EdU and immunofluorescence (IF). Autophagic flow was measured by mCherry-GFP-LC3B staining and transmission electron microscopy (TEM). YB-1 expression was measured by immunofluorescence and western blotting. CUT & Tag analysis, chromatin immunoprecipitation, and RT-PCR were performed to explore the regulation of autophagy-related protein 7 (Atg7) transcription by YB-1. Our results indicated that liver injury was accompanied by high expression of YB-1, proliferative HPCs, and activated autophagy in the CDE and DDC models. YB-1f/f Cre+/- mice displayed less liver injury and fibrosis than YB-1f/f Cre-/- mice in the CDE and DDC models. YB-1 promoted proliferation and autophagy of HPCs in vitro and in vivo. Transforming growth factor-β (TGF-β) induced YB-1 nuclear translocation and facilitated the proliferation and autophagy of HPCs. YB-1 nuclear translocation promoted the transcription of Atg7, which is essential for TGF-β/YB-1 mediated HPCs expansion in vitro and in vivo. In summary, YB-1 nuclear translocation induced by TGF-β in HPCs promotes the proliferation and autophagy of HPCs and Atg7 participates in YB-1-mediated HPC-expansion and liver fibrosis.
7375. qGL3/OsPPKL1 induces phosphorylation of 14-3-3 protein OsGF14b to inhibit OsBZR1 function in brassinosteroid signaling.
作者: Xiuying Gao.;Jiaqi Zhang.;Guang Cai.;Huaying Du.;Jianbo Li.;Ruqin Wang.;Yuji Wang.;Jing Yin.;Wencai Zhang.;Hongsheng Zhang.;Ji Huang.
来源: Plant Physiol. 2022年188卷1期624-636页
Brassinosteroids (BRs) play essential roles in regulating plant growth and development, however, gaps still remain in our understanding of the BR signaling network. We previously cloned a grain length quantitative trait locus qGL3, encoding a rice (Oryza sativa L.) protein phosphatase with Kelch-like repeat domain (OsPPKL1), that negatively regulates grain length and BR signaling. To further explore the BR signaling network, we performed phosphoproteomic analysis to screen qGL3-regulated downstream components. We selected a 14-3-3 protein OsGF14b from the phosphoproteomic data for further analysis. qGL3 promoted the phosphorylation of OsGF14b and induced the interaction intensity between OsGF14b and OsBZR1. In addition, phosphorylation of OsGF14b played an important role in regulating nucleocytoplasmic shuttling of OsBZR1. The serine acids (Ser258Ser259) residues of OsGF14b play an essential role in BR-mediated responses and plant development. Genetic and molecular analyses indicated that OsGF14b functions as a negative regulator in BR signaling and represses the transcriptional activation activity of OsBZR1. Collectively, these results demonstrate that qGL3 induces the phosphorylation of OsGF14b, which modulates nucleocytoplasmic shuttling and transcriptional activation activity of OsBZR1, to eventually negatively regulate BR signaling and grain length in rice.
7376. Pyridoxal and α-Ketoglutarate Independently Improve Function of Saccharomyces cerevisiae Thi5 in the Metabolic Network of Salmonella enterica.
Microbial metabolism is often considered modular, but metabolic engineering studies have shown that transferring pathways, or modules, between organisms is not always straightforward. The Thi5-dependent pathway(s) for synthesis of the pyrimidine moiety of thiamine from Saccharomyces cerevisiae and Legionella pneumophila functioned differently when incorporated into the metabolic network of Salmonella enterica. Function of Thi5 from Saccharomyces cerevisiae (ScThi5) required modification of the underlying metabolic network, while LpThi5 functioned with the native network. Here we probe the metabolic requirements for heterologous function of ScThi5 and report strong genetic and physiological evidence for a connection between alpha-ketoglutarate (αKG) levels and ScThi5 function. The connection was built with two classes of genetic suppressors linked to metabolic flux or metabolite pool changes. Further, direct modulation of nitrogen assimilation through nutritional or genetic modification implicated αKG levels in Thi5 function. Exogenous pyridoxal similarly improved ScThi5 function in S. enterica. Finally, directly increasing αKG and PLP with supplementation improved function of both ScThi5 and relevant variants of Thi5 from Legionella pneumophila (LpThi5). The data herein suggest structural differences between ScThi5 and LpThi5 impact their level of function in vivo and implicate αKG in supporting function of the Thi5 pathway when placed in the heterologous metabolic network of S. enterica. IMPORTANCE Thiamine biosynthesis is a model metabolic node that has been used to extend our understanding of metabolic network structure and individual enzyme function. The requirements for in vivo function of the Thi5-dependent pathway found in Legionella and yeast are poorly characterized. Here we suggest that αKG modulates function of the Thi5 pathway in S. enterica and provide evidence that structural variation between ScThi5 and LpThi5 contributes to their functional differences in a Salmonella enterica host.
7377. Identification of Indole-3-Acetic Acid-Regulated Genes in Pseudomonas syringae pv. tomato Strain DC3000.
作者: Arnaud-Thierry Djami-Tchatchou.;Zipeng Alex Li.;Paul Stodghill.;Melanie J Filiatrault.;Barbara N Kunkel.
来源: J Bacteriol. 2022年204卷1期e0038021页
The auxin indole-3-acetic acid (IAA) is a plant hormone that not only regulates plant growth and development but also plays important roles in plant-microbe interactions. We previously reported that IAA alters expression of several virulence-related genes in the plant pathogen Pseudomonas syringae pv. tomato strain DC3000 (PtoDC3000). To learn more about the impact of IAA on regulation of PtoDC3000 gene expression, we performed a global transcriptomic analysis of bacteria grown in culture, in the presence or absence of exogenous IAA. We observed that IAA repressed expression of genes involved in the type III secretion (T3S) system and motility and promoted expression of several known and putative transcriptional regulators. Several of these regulators are orthologs of factors known to regulate stress responses and accordingly expression of several stress response-related genes was also upregulated by IAA. Similar trends in expression for several genes were also observed by quantitative reverse transcription PCR. Using an Arabidopsis thaliana auxin receptor mutant that accumulates elevated auxin, we found that many of the P. syringae genes regulated by IAA in vitro were also regulated by auxin in planta. Collectively the data indicate that IAA modulates many aspects of PtoDC3000 biology, presumably to promote both virulence and survival under stressful conditions, including those encountered in or on plant leaves. IMPORTANCE Indole-3-acetic acid (IAA), a form of the plant hormone auxin, is used by many plant-associated bacteria as a cue to sense the plant environment. Previously, we showed that IAA can promote disease in interactions between the plant pathogen Pseudomonas syringae strain PtoDC000 and one of its hosts, Arabidopsis thaliana. However, the mechanisms by which IAA impacts the biology of PtoDC3000 and promotes disease are not well understood. Here, we demonstrate that IAA is a signal molecule that regulates gene expression in PtoDC3000. The presence of exogenous IAA affects expression of over 700 genes in the bacteria, including genes involved in type III secretion and genes involved in stress response. This work offers insight into the roles of auxin-promoting pathogenesis.
7378. The jasmonic acid-amino acid conjugates JA-Val and JA-Leu are involved in rice resistance to herbivores.
作者: Wenjie Fu.;Gaochen Jin.;Guillermo H Jiménez-Alemán.;Xinjue Wang.;Jiajin Song.;Suhua Li.;Yonggen Lou.;Ran Li.
来源: Plant Cell Environ. 2022年45卷1期262-272页
The phytohormone jasmonic acid (JA) plays a core role in plant defence against herbivores. When attacked by herbivores, JA and its bioactive derivatives are accumulated at the damage site, and subsequently perceived by the jasmonate co-receptors COI1 and JAZ proteins. The (+)-7-iso-jasmonoyl-L-isoleucine (JA-Ile) is known to be the main active JA derivative controlling vascular plant responses to herbivores as well as other JA-regulated processes. However, whether other endogenous JA-amino acid conjugates (JA-AAs) are involved in herbivore-induced defence responses remain unknown. Here, we investigated the role of herbivore-elicited JA-AAs in the crop plant rice. The levels of five JA-AAs were significantly increased under the armyworm, leaf folder and brown planthopper attack. Of the elicited JA derivatives, JA-Ile, JA-Val and JA-Leu could serve as ligands to promote the interaction between rice COI1 and JAZs, inducing OsJAZ4 degradation in vivo. JA-Val or JA-Leu treatment increased the expression of JA- and defence-related pathway genes but not JA-Ile levels, suggesting that these JA-AAs may directly function in JA signalling. Furthermore, the application of JA-Val or JA-Leu resulted in JA-mediated plant growth inhibition, while enhancing plant resistance to herbivore attack. This study uncovers that JA-Val and JA-Leu also play a role in rice defence against herbivores.
7379. Effect of vitamin D supplementation on OPG/RANKL signalling activities in endothelial tissue damage in diet-induced diabetic rat model.
作者: Gizem Celebi.;Merve Anapali.;Fatma Kaya Dagistanli.;Ayse Seda Akdemir.;Duygu Aydemir.;Nuriye Nuray Ulusu.;Turgut Ulutin.;Evrim Komurcu-Bayrak.
来源: Pharmacol Rep. 2022年74卷1期124-134页
Type 2 Diabetes Mellitus is a chronic metabolic disease that causes endothelial damage and is an important risk factor for atherosclerosis. In the present study vitamin D3 supplementation in rats was used to determine the role of Osteoprotegerin (OPG)/Receptor activator kB ligand (RANKL) signalling in endothelial damage and changes in the expression levels of genes involved in this pathway. We hypothesized that vitamin D3 supplementation affects OPG and RANKL activity in the aorta.
7380. The potential neuroprotective effect of diosmin in rotenone-induced model of Parkinson's disease in rats.
作者: Christine N Habib.;Mohamed R Mohamed.;Mariane G Tadros.;Mai F Tolba.;Esther T Menze.;Somia I Masoud.
来源: Eur J Pharmacol. 2022年914卷174573页
Most treatments for Parkinson's disease (PD) focus on improving the symptoms and the dopaminergic effects; nevertheless, they cannot delay the disease progression. Diosmin (DM), a naturally occurring flavone that is obtained from citrus fruits, has demonstrated anti-apoptotic, anti-inflammatory and antioxidative properties in many diseases. This study aimed to assess the neuroprotective effects of diosmin in rotenone-induced rat model of PD and investigate its potential underlying mechanisms. A preliminary dose-response study was conducted where rats were treated with DM (50,100 and 200 mg/kg, p.o.) concomitantly with rotenone (2 mg/kg, s.c.) for 4 weeks. Catalepsy, motor impairment, spontaneous locomotion, body weight, histological examination and tyrosine hydroxylase (TH) immunoreactivity were evaluated in both the midbrains and striata of rats. Treatment with DM (200 mg/kg) showed the most promising outcome therefore, it was selected for further evaluation of α-synuclein, Bax, Bcl2, nuclear factor kappa B (NF-кB), nuclear factor erythroid 2- related factor 2 (Nrf2), and heme oxygenase-1 (HO-1), in addition to biochemical analysis of tumor necrosis factor-α (TNF-α). Results showed that DM (200 mg/kg, p.o.) prevented rotenone-induced motor impairment, weight reduction and histological damage. Furthermore, it significantly inhibited rotenone-induced decrease in TH expression. These results were correlated with reduction in α-synuclein immunoreactivity, together with improvement of Bax/Bcl2 ratio compared to rotenone group. DM also attenuated rotenone-induced increase in NF-кB expression as well as TNF- α levels. Moreover, DM inhibited rotenone-induced upregulation of Nrf2/HO-1 pathway. Thus, the current study suggests that DM might be a promising candidate for managing the neuropathological course of PD.
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