The molecular mechanisms of brassinosteroid-regulated drought stress response in Arabidopsis thaliana

Brassinosteroids (BRs) are involved in diverse developmental processes such as cell elongation, vascular differentiation, senescence and stress response. The mechanisms and regulatory networks of BR-regulated plant growth and development have been well described for the past decade with the identification of receptors, kinases and central transcription factors involved in BR signaling. Recent studies revealed BRs also extensively participated in plant response to environmental stresses, although the mechanisms of BR-regulated stress response is largely unknown. Coordination of plant growth and stress response requires integration of multiple signaling output through hormonal crosstalk. Studies of BR signaling pathway and BR-mediated physiological responses indicate there are intensive interactions between BRs and other phytohormones such as auxin, abscisic acid, jasmonic acid and ethylene. This study aims to unravel the function and regulatory mechanisms of BRs in abiotic stresses, particularly drought stress, through the investigation of the crosstalk between BR and drought/ABA signaling pathways. Through genetic, genomic and biochemical assays, we identified a transcription factor RESPONSIVE TO DESSICATION 26 (RD26) that mediates the the crosstalk between BR and ABA signaling pathways, and proposed a regulatory model that coordinates plant growth and stress response

Discovery, Characterization, and Development of Small Molecule Inhibitors of Glycogen Synthase

Indiana University-Purdue University Indianapolis (IUPUI)The over-accumulation of glycogen appears as a hallmark in various glycogen storage diseases (GSDs), including Pompe, Cori, Andersen, and Lafora disease. Glycogen synthase (GS) is the rate-limiting enzyme for glycogen synthesis. Recent evidence suggests that suppression of glycogen accumulation represents a potential therapeutic approach for treating these diseases. Herein, we describe the discovery, characterization, and development of small molecule inhibitors of GS through a multicomponent study including biochemical, biophysical, and cellular assays. Adopting an affinity-based fluorescence polarization assay, we identified a substituted imidazole molecule (H23), as a first-in-class inhibitor of yeast glycogen synthase 2 (yGsy2) from the 50,000 ChemBridge DIVERSet library. Structural data derived from X-ray crystallography at 2.85 Å, and enzyme kinetic data, revealed that H23 bound within the uridine diphosphate glucose binding pocket of yGsy2. Medicinal chemistry efforts examining over 500 H23 analogs produced structure-activity relationship (SAR) profiles that led to the identification of potent pyrazole and isoflavone compounds with low micromolar potency against human glycogen synthase 1 (hGYS1). Notably, several of the isoflavones demonstrated cellular efficacy toward suppressing glycogen accumulation. In an alternative effort to screen inhibitors directly against human GS, an activity-based assay was designed using a two-step colorimetric approach. This assay led to the identification of compounds with submicromolar potency to hGYS1 from a chemical library comprised of 10,000 compounds. One of the hit molecules, hexachlorophene, was crystallized bound to the active site of yGsy2. The structure was determined to 3.15 Å. Additional kinetic, mutagenic, and SAR studies validated the binding of hexachlorophene in the catalytic pocket and its non-competitive mode of inhibition. In summary, these two novel assays provided feasible biochemical platforms for large-scale screening of small molecule modulators of GS. The newly-developed, potent analogs possess diverse promising scaffolds for drug development efforts targeting GS activity in GSDs associated with excess glycogen accumulation.2021-07-0

Ferrochelatase is a therapeutic target for ocular neovascularization

Ocular neovascularization underlies major blinding eye diseases such as “wet” age-related macular degeneration (AMD). Despite the successes of treatments targeting the vascular endothelial growth factor (VEGF) pathway, resistant and refractory patient populations necessitate discovery of new therapeutic targets. Using a forward chemical genetic approach, we identified the heme synthesis enzyme ferrochelatase (FECH) as necessary for angiogenesis in vitro and in vivo. FECH is overexpressed in wet AMD eyes and murine choroidal neovascularization; siRNA knockdown of Fech or partial loss of enzymatic function in the Fechm1Pas mouse model reduces choroidal neovascularization. FECH depletion modulates endothelial nitric oxide synthase function and VEGF receptor 2 levels. FECH is inhibited by the oral antifungal drug griseofulvin, and this compound ameliorates choroidal neovascularization in mice when delivered intravitreally or orally. Thus, FECH inhibition could be used therapeutically to block ocular neovascularization

Discovery and Development of Small-Molecule Inhibitors of Glycogen Synthase

The overaccumulation of glycogen appears as a hallmark in various glycogen storage diseases (GSDs), including Pompe, Cori, Andersen, and Lafora disease. Accumulating evidence suggests that suppression of glycogen accumulation represents a potential therapeutic approach for treating these GSDs. Using a fluorescence polarization assay designed to screen for inhibitors of the key glycogen synthetic enzyme, glycogen synthase (GS), we identified a substituted imidazole, (rac)-2-methoxy-4-(1-(2-(1-methylpyrrolidin-2-yl)ethyl)-4-phenyl-1H-imidazol-5-yl)phenol (H23), as a first-in-class inhibitor for yeast GS 2 (yGsy2p). Data from X-ray crystallography at 2.85 Å, as well as kinetic data, revealed that H23 bound within the uridine diphosphate glucose binding pocket of yGsy2p. The high conservation of residues between human and yeast GS in direct contact with H23 informed the development of around 500 H23 analogs. These analogs produced a structure–activity relationship profile that led to the identification of a substituted pyrazole, 4-(4-(4-hydroxyphenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl)pyrogallol, with a 300-fold improved potency against human GS. These substituted pyrazoles possess a promising scaffold for drug development efforts targeting GS activity in GSDs associated with excess glycogen accumulation

The molecular mechanisms of brassinosteroid-regulated drought stress response in Arabidopsis thaliana

Brassinosteroids (BRs) are involved in diverse developmental processes such as cell elongation, vascular differentiation, senescence and stress response. The mechanisms and regulatory networks of BR-regulated plant growth and development have been well described for the past decade with the identification of receptors, kinases and central transcription factors involved in BR signaling. Recent studies revealed BRs also extensively participated in plant response to environmental stresses, although the mechanisms of BR-regulated stress response is largely unknown. Coordination of plant growth and stress response requires integration of multiple signaling output through hormonal crosstalk. Studies of BR signaling pathway and BR-mediated physiological responses indicate there are intensive interactions between BRs and other phytohormones such as auxin, abscisic acid, jasmonic acid and ethylene. This study aims to unravel the function and regulatory mechanisms of BRs in abiotic stresses, particularly drought stress, through the investigation of the crosstalk between BR and drought/ABA signaling pathways. Through genetic, genomic and biochemical assays, we identified a transcription factor RESPONSIVE TO DESSICATION 26 (RD26) that mediates the the crosstalk between BR and ABA signaling pathways, and proposed a regulatory model that coordinates plant growth and stress response.</p

A Data-Driven Based Method for Pipeline Additional Stress Prediction Subject to Landslide Geohazards

Pipelines that cross complex geological terrains are inevitably threatened by natural hazards, among which landslide attracts extensive attention when pipelines cross mountainous areas. The landslides are typically associated with ground movements that would induce additional stress on the pipeline. Such stress state of pipelines under landslide interference seriously damage structural integrity of the pipeline. Up to the date, limited research has been done on the combined landslide hazard and pipeline stress state analysis. In this paper, a multi-parameter integrated monitoring system was developed for the pipeline stress-strain state and landslide deformation monitoring. Also, data-driven models for the pipeline additional stress prediction was established. The developed predictive models include individual and ensemble-based machine learning approaches. The implementation procedure of the predictive models integrates the field data measured by the monitoring system, with k-fold cross validation used for the generalization performance evaluation. The obtained results indicate that the XGBoost model has the highest performance in the prediction of the additional stress. Besides, the significance of the input variables is determined through sensitivity analyses by using feature importance criteria. Thus, the integrated monitoring system together with the XGBoost prediction method is beneficial to modeling the additional stress in oil and gas pipelines, which will further contribute to pipeline geohazards monitoring management

The Role of Xuefu Zhuyu Decoction in Prevention of Contrast-Induced Nephropathy after Percutaneous Coronary Intervention

Objective. This study aimed to investigate the effect of Xuefu Zhuyu decoction on preventing contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI). Methods. A total of 256 patients undergoing selective PCI for coronary artery disease were consecutively enrolled and randomly divided into two groups: Group A (n = 126) and Group B (n = 130). Before and after PCI, all patients routinely received antiplatelet aggregation therapy, antilipidemic therapy, and hydration therapy. Besides routine therapy, patients in Group B received Xuefu Zhuyu decoction from 3 days before PCI to 3 days after PCI. Serum creatinine (Scr), estimated glomerular filtration rate (eGFR), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured, respectively, at baseline (72 h before PCI) and at 24, 48, and 72 h after PCI. Results. Compared with Group A, Group B presented a lower fluctuation of SCr and eGFR (P<0.01). The incidence of CIN was less in Group B. According to the definition, CIN occurred in 5 patients (2.0%) in the intervention group and 5 (4.0%) in the control group (P=0.167). In terms of oxidative stress, Group B had a lower MDA (P<0.05), but a higher SOD (P<0.05). Conclusions. Compared with the control group, Xuefu Zhuyu decoction intervention therapy increased the level of SOD and reduced MDA. The Xuefu Zhuyu decoction intervention group presented a higher level of eGFR at 24, 48, and 72 h after PCI in patients with coronary heart disease and a lower level of Scr. The results are propitious to prove that Xuefu Zhuyu decoction might play an antioxidative stress role in the prevention of CIN after PCI