39 research outputs found

    TMK1-mediated auxin signalling regulates differential growth of the apical hook

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    The plant hormone auxin has crucial roles in almost all aspects of plant growth and development. Concentrations of auxin vary across different tissues, mediating distinct developmental outcomes and contributing to the functional diversity of auxin. However, the mechanisms that underlie these activities are poorly understood. Here we identify an auxin signalling mechanism, which acts in parallel to the canonical auxin pathway based on the transport inhibitor response1 (TIR1) and other auxin receptor F-box (AFB) family proteins (TIR1/AFB receptors)1,2, that translates levels of cellular auxin to mediate differential growth during apical-hook development. This signalling mechanism operates at the concave side of the apical hook, and involves auxin-mediated C-terminal cleavage of transmembrane kinase 1 (TMK1). The cytosolic and nucleus-translocated C terminus of TMK1 specifically interacts with and phosphorylates two non-canonical transcriptional repressors of the auxin or indole-3-acetic acid (Aux/IAA) family (IAA32 and IAA34), thereby regulating ARF transcription factors. In contrast to the degradation of Aux/IAA transcriptional repressors in the canonical pathway, the newly identified mechanism stabilizes the non-canonical IAA32 and IAA34 transcriptional repressors to regulate gene expression and ultimately inhibit growth. The auxin–TMK1 signalling pathway originates at the cell surface, is triggered by high levels of auxin and shares a partially overlapping set of transcription factors with the TIR1/AFB signalling pathway. This allows distinct interpretations of different concentrations of cellular auxin, and thus enables this versatile signalling molecule to mediate complex developmental outcomes

    Celastrol targets mitochondrial respiratory chain complex I to induce reactive oxygen species-dependent cytotoxicity in tumor cells

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    <p>Abstract</p> <p>Background</p> <p>Celastrol is an active ingredient of the traditional Chinese medicinal plant <it>Tripterygium Wilfordii</it>, which exhibits significant antitumor activity in different cancer models <it>in vitro </it>and <it>in vivo</it>; however, the lack of information on the target and mechanism of action of this compound have impeded its clinical application. In this study, we sought to determine the mode of action of celastrol by focusing on the processes that mediate its anticancer activity.</p> <p>Methods</p> <p>The downregulation of heat shock protein 90 (HSP90) client proteins, phosphorylation of c-Jun NH2-terminal kinase (JNK), and cleavage of PARP, caspase 9 and caspase 3 were detected by western blotting. The accumulation of reactive oxygen species (ROS) was analyzed by flow cytometry and fluorescence microscopy. Cell cycle progression, mitochondrial membrane potential (MMP) and apoptosis were determined by flow cytometry. Absorption spectroscopy was used to determine the activity of mitochondrial respiratory chain (MRC) complexes.</p> <p>Results</p> <p>Celastrol induced ROS accumulation, G2-M phase blockage, apoptosis and necrosis in H1299 and HepG2 cells in a dose-dependent manner. N-acetylcysteine (NAC), an antioxidative agent, inhibited celastrol-induced ROS accumulation and cytotoxicity. JNK phosphorylation induced by celastrol was suppressed by NAC and JNK inhibitor SP600125 (SP). Moreover, SP significantly inhibited celastrol-induced loss of MMP, cleavage of PARP, caspase 9 and caspase 3, mitochondrial translocation of Bad, cytoplasmic release of cytochrome c, and cell death. However, SP did not inhibit celastrol-induced ROS accumulation. Celastrol downregulated HSP90 client proteins but did not disrupt the interaction between HSP90 and cdc37. NAC completely inhibited celastrol-induced decrease of HSP90 client proteins, catalase and thioredoxin. The activity of MRC complex I was completely inhibited in H1299 cells treated with 6 μM celastrol in the absence and presence of NAC. Moreover, the inhibition of MRC complex I activity preceded ROS accumulation in H1299 cells after celastrol treatment.</p> <p>Conclusion</p> <p>We identified ROS as the key intermediate for celastrol-induced cytotoxicity. JNK was activated by celastrol-induced ROS accumulation and then initiated mitochondrial-mediated apoptosis. Celastrol induced the downregulation of HSP90 client proteins through ROS accumulation and facilitated ROS accumulation by inhibiting MRC complex I activity. These results identify a novel target for celastrol-induced anticancer activity and define its mode of action.</p

    Diagnosis Method for Mechanical Faults Based on Rotation Synchroextracting Chirplet Transform

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    The problems of the synchroextracting transform method being unable to handle FM signals and being prone to time–frequency feature discontinuity in a strong noise environment are addressed by the construction of a novel rotation synchroextracting chirplet transform under the framework of the synchroextracting transform. The method retains the advantage of the generalized linear chirplet transform that can fit the time–frequency characteristics of the original signal and retains the high precision time–frequency analysis ability of the synchroextracting transform. The simulation results show that the proposed method is obviously superior to the generalized chirplet transform and synchroextracting transform method. The method can obtain the time–frequency energy located at the time–frequency ridges of FM-AM signals and multicomponent signals with crossed-frequency components, and has high time–frequency analysis ability and anti-interference ability. Finally, the proposed method is applied to diagnose mechanical faults. The experimental results further verify the effectiveness of the proposed method, which can effectively extract the characteristic freque.ncy of fault signal

    Plasmonic Bi-Modified Bi<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub> Nanosheets for Efficient Photocatalytic NO Removal

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    The photocatalytic removal of nitric oxide (NO) is a promising technology used to reduce the level of harmful gaseous pollutants in parts per billion (ppb). As a potential photocatalyst, Bi2Sn2O7 has a low quantum efficiency due to its fast recombination rate of photo-generated carriers. In this paper, Bi/Bi2Sn2O7 was prepared by the in situ deposition of Bi. The structural, electrical, and optical properties of the attained sample were investigated through a series of analyses. The results demonstrate that Bi nanoparticles not only enhance the photoabsorption ability of Bi2Sn2O7 due to their surface plasmon resonance (SPR) effect, but also improve its photocatalytic activity. Photocatalytic performance was evaluated by the oxidation of NO at ppb level under xenon lamp (λ > 400 nm) irradiation. It was found that the photocatalytic NO removal rate increased from 7.2% (Bi2Sn2O7) to 38.6% (Bi/Bi2Sn2O7). The loading of Bi promotes the separation and migration of photo-generated carriers and enhances the generation of •O2− and •OH radicals responsible for the oxidation of NO. The Bi/Bi2Sn2O7 composite photocatalyst also exhibits excellent photocatalytic stability, which makes it a potential candidate for use in air purification systems

    Estimated cardiorespiratory fitness and incident risk of cardiovascular disease in China

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    Abstract Background Limited evidence is available on the association between estimated cardiorespiratory fitness (e-CRF) and incidence of cardiovascular disease (CVD) in Chinese population. Methods A total of 10,507 adults including 5084 men (48.4%) and 5423 (51.6%) women with a median age of 56.0 (25% quantile: 49, 75% quantile 63) years from the China Health and Retirement Longitudinal Study (CHARLS) was recruited in 2011 as baseline. The CVD incident events were followed-up until 2018. e-CRF was calculated from sex-specific longitudinal non-exercise equations and further grouped into quartiles. Cox proportional models were used to calculate hazard ratio (HR) and 95% confidence interval (CI) for incidence risks of CVD, heart disease and stroke. Results During a median follow-up of 7 years, a total of 1862 CVD, 1409 heart disease and 612 stroke events occurred. In fully adjusted models, each one MET increment of e-CRF was associated with lower risk of CVD (HR = 0.91, 95%CI = 0.85–0.96 for males, HR = 0.87, 95%CI = 0.81–0.94 for females). Compared with the Quartile (Q)1 group, the HRs (95%CI) of the Q2, Q3 and Q4 groups were 0.84 (0.63–1.03), 0.72 (0.57–0.91) and 0.66 (0.51–0.87) for CVD in males. Females had HRs of 0.79 (0.66–0.96) in Q2, 0.71 (0.57–0.88) in Q3 and 0.58 (0.45–0.75) in Q4 for CVD. The associations between e-CRF and heart disease and stroke were slightly weaker than that for CVD in both males and females. Conclusions Higher e-CRF decreases the incident risk of CVD, heart disease and stroke

    Lymph node metastasis in cancer progression: molecular mechanisms, clinical significance and therapeutic interventions

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    Abstract Lymph nodes (LNs) are important hubs for metastatic cell arrest and growth, immune modulation, and secondary dissemination to distant sites through a series of mechanisms, and it has been proved that lymph node metastasis (LNM) is an essential prognostic indicator in many different types of cancer. Therefore, it is important for oncologists to understand the mechanisms of tumor cells to metastasize to LNs, as well as how LNM affects the prognosis and therapy of patients with cancer in order to provide patients with accurate disease assessment and effective treatment strategies. In recent years, with the updates in both basic and clinical studies on LNM and the application of advanced medical technologies, much progress has been made in the understanding of the mechanisms of LNM and the strategies for diagnosis and treatment of LNM. In this review, current knowledge of the anatomical and physiological characteristics of LNs, as well as the molecular mechanisms of LNM, are described. The clinical significance of LNM in different anatomical sites is summarized, including the roles of LNM playing in staging, prognostic prediction, and treatment selection for patients with various types of cancers. And the novel exploration and academic disputes of strategies for recognition, diagnosis, and therapeutic interventions of metastatic LNs are also discussed

    Conformational selection turns on phenylalanine hydroxylase

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    The Flow Pattern Transition and Water Holdup of Gas-Liquid Flow in the Horizontal and Vertical Sections of a Continuous Transportation Pipe

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    A series of experiments were conducted to investigate the flow pattern transitions and water holdup during oil-water-gas three-phase flow considering both a horizontal section and a vertical section of a transportation pipe simultaneously. The flowing media were white mineral oil, distilled water, and air. Dimensionless numbers controlling the multiphase flow were deduced to understand the scaling law of the flow process. The oil-water-gas three-phase flow was simplified as the two-phase flow of a gas and liquid mixture. Based on the experimental data, flow pattern maps were constructed in terms of the Reynolds number and the ratio of the superficial velocity of the gas to that of the liquid mixture for different Froude numbers. The original contributions of this work are that the relationship between the transient water holdup and the changes of the flow patterns in a transportation pipe with horizontal and vertical sections is established, providing a basis for judging the flow patterns in pipes in engineering practice. A dimensionless power-law correlation for the water holdup in the vertical section is presented based on the experimental data. The correlation can provide theoretical support for the design of oil and gas transport pipelines in industrial applications

    A multicenter randomized phase II trial of hyperthermia combined with TPF induction chemotherapy compared with TPF induction chemotherapy in locally advanced resectable oral squamous cell carcinoma

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    Background Hyperthermia has been reported to cause cancer stage regression, thus providing surgical opportunities in patients with unresectable tumors and improving the quality of life of patients by preserving certain organs. Methods A prospective open-label phase II trial was conducted to evaluate the efficacy of hyperthermia combined with induction chemotherapy in patients with locally advanced resectable oral squamous cell carcinoma (OSCC). Patients received hyperthermia combined with two cycles of 5-fluorouracil, cisplatin, and docetaxel (TPF) induction chemotherapy regimens or TPF induction chemotherapy alone, followed by radical surgery with postoperative radiotherapy. The primary endpoint was the clinical response rate of the induction chemotherapy. The secondary endpoints were overall survival (OS), disease-free survival (DFS), and toxicity. Results A total of 120 patients were enrolled, and 115 patients were included in the clinical response analysis. The clinical response rate was significantly higher in the experimental arm than in the control arm (65.45% vs. 40.00%, p = 0.0088). There were no unexpected toxicities, and hyperthermia and induction chemotherapy did not increase the perioperative morbidity rate. Moreover, there was a significant improvement in DFS, but no significant difference in OS between the two arms. In the subgroup analysis, increased OS and DFS rates were associated with patients with favorable clinical response after induction chemotherapy in the total population, experimental arm, and control arm. Conclusions Our study demonstrates that hyperthermia combined with induction chemotherapy is associated with a high response rate and provides a new treatment option for patients with resectable stage III or IVA OSCC

    Distinct mutations with different inheritance mode caused similar retinal dystrophies in one family: a demonstration of the importance of genetic annotations in complicated pedigrees

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    Abstract Background Retinitis pigmentosa (RP) is the most common form of inherited retinal dystrophy presenting remarkable genetic heterogeneity. Genetic annotations would help with better clinical assessments and benefit gene therapy, and therefore should be recommended for RP patients. This report reveals the disease causing mutations in two RP pedigrees with confusing inheritance patterns using whole exome sequencing (WES). Methods Twenty-five participants including eight patients from two families were recruited and received comprehensive ophthalmic evaluations. WES was applied for mutation identification. Bioinformatics annotations, intrafamilial co-segregation tests, and in silico analyses were subsequently conducted for mutation verification. Results All patients were clinically diagnosed with RP. The first family included two siblings born to parents with consanguineous marriage; however, no potential pathogenic variant was found shared by both patients. Further analysis revealed that the female patient carried a recurrent homozygous C8ORF37 p.W185*, while the male patient had hemizygous OFD1 p.T120A. The second family was found to segregate mutations in two genes, TULP1 and RP1. Two patients born to consanguineous marriage carried homozygous TULP1 p.R419W, while a recurrent heterozygous RP1 p.L762Yfs*17 was found in another four patients presenting an autosomal dominant inheritance pattern. Crystal structural analysis further indicated that the substitution from arginine to tryptophan at the highly conserved residue 419 of TULP1 could lead to the elimination of two hydrogen bonds between residue 419 and residues V488 and S534. All four genes, including C8ORF37, OFD1, TULP1 and RP1, have been previously implicated in RP etiology. Conclusions Our study demonstrates the coexistence of diverse inheritance modes and mutations affecting distinct disease causing genes in two RP families with consanguineous marriage. Our data provide novel insights into assessments of complicated pedigrees, reinforce the genetic complexity of RP, and highlight the need for extensive molecular evaluations in such challenging families with diverse inheritance modes and mutations
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