Discovery of a Plant 14-3-3 Inhibitor Possessing Isoform Selectivity and In Planta Activity

Synthetic modulators of plant 14-3-3s are promising chemical tools both for understanding the 14-3-3-related signaling pathways and controlling plant physiology. Herein, we describe a novel small-molecule inhibitor for 14-3-3 proteins of Arabidopsis thaliana. The inhibitor was identified from unexpected products in a stock solution in dimethyl sulfoxide (DMSO) of an in-house chemical library. Mass spectroscopy, mutant-based analyses, fluorescence polarization assays, and thermal shift assays revealed that the inhibitor covalently binds to an allosteric site of 14-3-3 with isoform selectivity. Moreover, infiltration of the inhibitor to Arabidopsis leaves suppressed the stomatal aperture. The inhibitor should provide new insight into the design of potent and isoform-selective 14-3-3 modulators.

Antiviral effects of micafungin against pteropine orthoreovirus, an emerging zoonotic virus carried by bats

Bat-borne emerging zoonotic viruses cause major outbreaks, such as the Ebola virus, Nipah virus, and/or beta coronavirus. Pteropine orthoreovirus (PRV), whose spillover event occurred from fruits bats to humans, causes respiratory syndrome in humans widely in South East Asia. Repurposing approved drugs against PRV is an effective tool to confront future PRV pandemics. We screened 2,943 compounds in an FDA-approved drug library and identified eight hit compounds that reduce viral cytopathic effects on cultured Vero cells. Real-time quantitative PCR analysis revealed that six of eight hit compounds significantly inhibited PRV replication. Among them, micafungin used clinically as an antifungal drug, displayed a prominent antiviral effect on PRV. Secondly, the antiviral effects of micafungin on PRV infected human cell lines (HEK293T and A549), and their transcriptome changes by PRV infection were investigated, compared to four different bat-derived cell lines (FBKT1 (Ryukyu flying fox), DEMKT1 (Leschenault's rousette), BKT1 (Greater horseshoe bat), YUBFKT1 (Eastern bent-wing bats)). In two human cell lines, unlike bat cells that induce an IFN-γ response pathway, an endoplasmic reticulum stress response pathway was commonly activated. Additionally, micafungin inhibits viral release rather than suppressing PRV genome replication in human cells, although it was disturbed in Vero cells. The target of micafungin's action may vary depending on the animal species, but it must be useful for human purposes as a first choice of medical care.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

β-adrenergic receptor regulates embryonic epithelial extensibility through actomyosin inhibition

During morphogenesis, epithelial tissues reshape and expand to cover the body and organs. The molecular mechanisms of this deformability remain elusive. Here, we investigate the role of the β-adrenergic receptor (ADRB) in orchestrating actomyosin contractility, pivotal for epithelial extensibility. Chemical screens on Xenopus laevis embryos pinpointed ADRB2 as a principal regulator. ADRB2 promotes actomyosin relaxation, facilitating apical cell area expansion during body elongation. In contrast, ADRB2 knockdown results in heightened cell contraction, marked by synchronous oscillation of F-actin and myosin, impeding body elongation. ADRB2 mutants with reduced affinity for ligand binding lack the function to induce cellular relaxation, highlighting the ligand's essential roles even in the developing epidermis. Our findings unveil ADRB2's critical contribution to extensibility of the epidermis and subsequent body elongation during development. This study also offers insights into the physiology of mature epithelial organs deformed by the smooth muscle response to the adrenergic autonomic nervous system.

A Small Compound, HYGIC, Promotes Hypocotyl Growth Through Ectopic Ethylene Response

Plant seedlings adjust the growth of the hypocotyl in response to surrounding environmental changes. Genetic studies have revealed key players and pathways in hypocotyl growth, such as phytohormones and light signaling. However, because of genetic redundancy in the genome, it is expected that not-yet-revealed mechanisms can be elucidated through approaches different from genetic ones. Here, we identified a small compound, HYGIC (HG), that simultaneously induces hypocotyl elongation and thickening, accompanied by increased nuclear size and enlargement of cortex cells. HG-induced hypocotyl growth required the ethylene signaling pathway activated by endogenous ethylene, involving CONSTITUTIVE PHOTOMORPHOGENIC 1, ETHYLENE INSENSITIVE 2 (EIN2) and redundant transcription factors for ethylene responses, ETHYLENE INSENSITIVE 3 (EIN3) and EIN3 LIKE 1. By using EBS:GUS, a transcriptional reporter of ethylene responses based on an EIN3-binding-cis-element, we found that HG treatment ectopically activates ethylene responses at the epidermis and cortex of the hypocotyl. RNA-seq and subsequent gene ontology analysis revealed that a significant number of HG-induced genes are related to responses to hypoxia. Indeed, submergence, a representative environment where the hypoxia response is induced in nature, promoted ethylene-signaling-dependent hypocotyl elongation and thickening accompanied by ethylene responses at the epidermis and cortex, which resembled the HG treatment. Collectively, the identification and analysis of HG revealed that ectopic responsiveness to ethylene promotes hypocotyl growth, and this mechanism is activated under submergence.

Formate-producing capacity provided by reducing ability of Streptococcus thermophilus nicotinamide adenine dinucleotide oxidase determines yogurt acidification rate

Yogurt is made by fermenting milk with 2 lactic acid bacteria, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. To comprehensively understand the protocooperation mechanism between S. thermophilus and L. bulgaricus in yogurt fermentation, we examined 24 combinations of cocultures comprising 7 fast- or slow-acidifying S. thermophilus strains with 6 fast- or slow-acidifying L. bulgaricus strains. Furthermore, 3 NADH oxidase (Nox)-deficient mutants (Δnox) and one pyruvate formate-lyase deficient mutant (ΔpflB) of S. thermophilus were used to evaluate the factor that determines the acidification rate of S. thermophilus. The results revealed that the acidification rate of S. thermophilus monoculture determined the yogurt fermentation rates, despite the coexistence of L. bulgaricus, whose acidification rate was either fast or slow. Significant correlation was found between the acidification rate of S. thermophilus monoculture and the amount of formate production. Result using ΔpflB showed that the formate was indispensable for the acidification of S. thermophilus. Moreover, results of the Δnox experiments revealed that formate production required Nox activity, which not only regulated dissolved oxygen, but also the redox potential. The Nox provided the large decrease in redox potential required by pyruvate formate-lyase to produce formate. A highly significant correlation was found between formate accumulation and Nox activity in S. thermophilus. In conclusion, the formate production ability provided by the action of Nox activity determines the acidification rate of S. thermophilus, and consequently, regulates yogurt coculture fermentation.

Identification and improvement of isothiocyanate-based inhibitors on stomatal opening to act as drought tolerance-conferring agrochemicals

Stomatal pores in the plant epidermis open and close to regulate gas exchange between leaves and the atmosphere. Upon light stimulation, the plasma membrane (PM) H⁺-ATPase is phosphorylated and activated via an intracellular signal transduction pathway in stomatal guard cells, providing a primary driving force for the opening movement. To uncover and manipulate this stomatal opening pathway, we screened a chemical library and identified benzyl isothiocyanate (BITC), a Brassicales-specific metabolite, as a potent stomatal-opening inhibitor that suppresses PM H⁺-ATPase phosphorylation. We further developed BITC derivatives with multiple isothiocyanate groups (multi-ITCs), which demonstrate inhibitory activity on stomatal opening up to 66 times stronger, as well as a longer duration of the effect and negligible toxicity. The multi-ITC treatment inhibits plant leaf wilting in both short (1.5 h) and long-term (24 h) periods. Our research elucidates the biological function of BITC and its use as an agrochemical that confers drought tolerance on plants by suppressing stomatal opening.

Novel inhibitors of microtubule organization and phragmoplast formation in diverse plant species

Cell division is essential for development and involves spindle assembly, chromosome separation, and cytokinesis. In plants, the genetic tools for controlling the events in cell division at the desired time are limited and ineffective owing to high redundancy and lethality. Therefore, we screened cell division-affecting compounds in Arabidopsis thaliana zygotes, whose cell division is traceable without time-lapse observations. We then determined the target events of the identified compounds using live-cell imaging of tobacco BY-2 cells. Subsequently, we isolated two compounds, PD-180970 and PP2, neither of which caused lethal damage. PD-180970 disrupted microtubule (MT) organization and, thus, nuclear separation, and PP2 blocked phragmoplast formation and impaired cytokinesis. Phosphoproteomic analysis showed that these compounds reduced the phosphorylation of diverse proteins, including MT-associated proteins (MAP70) and class II Kinesin-12. Moreover, these compounds were effective in multiple plant species, such as cucumber (Cucumis sativus) and moss (Physcomitrium patens). These properties make PD-180970 and PP2 useful tools for transiently controlling plant cell division at key manipulation nodes conserved across diverse plant species.

Identification of a pluripotency-inducing small compound, PLU, that induces callus formation via Heat Shock Protein 90-mediated activation of auxin signaling

Plants retain the ability to generate a pluripotent tissue called callus by dedifferentiating somatic cells. A pluripotent callus can also be artificially induced by culturing explants with hormone mixtures of auxin and cytokinin, and an entire body can then be regenerated from the callus. Here we identified a pluripotency-inducing small compound, PLU, that induces the formation of callus with tissue regeneration potency without the external application of either auxin or cytokinin. The PLU-induced callus expressed several marker genes related to pluripotency acquisition via lateral root initiation processes. PLU-induced callus formation required activation of the auxin signaling pathway though the amount of active auxin was reduced by PLU treatment. RNA-seq analysis and subsequent experiments revealed that Heat Shock Protein 90 (HSP90) mediates a significant part of the PLU-initiated early events. We also showed that HSP90-dependent induction of TRANSPORT INHIBITOR RESPONSE 1, an auxin receptor gene, is required for the callus formation by PLU. Collectively, this study provides a new tool for manipulating and investigating the induction of plant pluripotency from a different angle from the conventional method with the external application of hormone mixtures.

Oxidative Stress Inhibits Endotoxin Tolerance and May Affect Periodontitis

Periodontal disease is caused by dysbiosis of the dental biofilm and the host inflammatory response. Various pathogenic factors, such as proteases and lipopolysaccharides (LPSs) produced by bacteria, are involved in disease progression. Endotoxin tolerance is a function of myeloid cells, which sustain inflammation and promote tissue regeneration upon prolonged stimulation by endotoxins such as LPS. The role of endotoxin tolerance is gaining attention in various chronic inflammatory diseases, but its role in periodontal disease remains elusive. Oxidative stress, one of the major risk factors for periodontal disease, promotes disease progression through various mechanisms, of which only some are known. The effect of oxidative stress on endotoxin tolerance has not yet been studied, and we postulated that endotoxin tolerance regulation may be an additional mechanism through which oxidative stress influences periodontal disease. This study aimed to reveal the effect of oxidative stress on endotoxin tolerance and that of endotoxin tolerance on periodontitis progression. The effect of oxidative stress on endotoxin tolerance was analyzed in vitro using peritoneal macrophages of mice and hydrogen peroxide (H₂O₂). The results showed that oxidative stress inhibits endotoxin tolerance induced by Porphyromonas gingivalis LPS in macrophages, at least partially, by downregulating LPS-elicited negative regulators of Toll-like receptor (TLR) signaling. A novel oxidative stress mouse model was established using SMP30KO mice incapable of ascorbate biosynthesis. Using this model, we revealed that oxidative stress impairs endotoxin tolerance potential in macrophages in vivo. Furthermore, gingival expression of endotoxin tolerance-related genes and TLR signaling negative regulators was decreased, and symptoms of ligature-induced periodontitis were aggravated in the oxidative stress mouse model. Our findings suggest that oxidative stress may contribute to periodontitis progression through endotoxin tolerance inhibition.

Discovery of 2,6-Dihalopurines as Stomata Opening Inhibitors: Implication of an LRX-Mediated H+-ATPase Phosphorylation Pathway

Stomata are pores in the leaf epidermis of plants and their opening and closing regulate gas exchange and water transpiration. Stomatal movements play key roles in both plant growth and stress responses. In recent years, small molecules regulating stomatal movements have been used as a powerful tool in mechanistic studies, as well as key players for agricultural applications. Therefore, the development of new molecules regulating stomatal movement and the elucidation of their mechanisms have attracted much attention. We herein describe the discovery of 2,6-dihalopurines, AUs, as a new stomatal opening inhibitor, and their mechanistic study. Based on biological assays, AUs may involve in the pathway related with plasma membrane H⁺-ATPase phosphorylation. In addition, we identified leucine-rich repeat extensin proteins (LRXs), LRX3, LRX4 and LRX5 as well as RALF, as target protein candidates of AUs by affinity based pull down assay and molecular dynamics simulation. The mechanism of stomatal movement related with the LRXs-RALF is an unexplored pathway, and therefore further studies may lead to the discovery of new signaling pathways and regulatory factors in the stomatal movement.

Association Between Nonadherence and Transient Hyperuricemia in Pediatric Kidney Transplantation

BACKGROUND

Nonadherence among pediatric transplant recipients is a significant problem that reduces graft survival and leads to poor kidney graft outcomes. It is, however, extremely difficult to detect during a regular follow-up. This study, therefore, aimed to investigate the risk factors involved in nonadherence, focusing on unexplained transient hyperuricemia in pediatric kidney transplant (KTx) recipients at a single pediatric center.

METHODS

This retrospective study included 167 patients who underwent KTx at our pediatric center. A Cox proportional hazards analysis was performed to evaluate the risk of nonadherence using the following factors: age, sex, body mass index SD score, transient hyperuricemia, hypertension, and follow-up period.

RESULTS

Nonadherence was identified in 19 patients (11%), with the average (SD) age and post-KTx duration at diagnosis being 17.21 (4.73) years and 79.21 (38.77) months, respectively. Thirty-four patients (20%) were diagnosed with transient hyperuricemia at a median of 14 months after KTx. On multivariate Cox regression analysis, transient hyperuricemia was the only independent risk factor for nonadherence after KTx.

CONCLUSIONS

Transient hyperuricemia was identified as one of the risk factors for nonadherence after KTx; therefore, careful monitoring for transient hyperuricemia may allow early detection of nonadherence.

Prostaglandin E2 synchronizes lunar-regulated beach spawning in grass puffers

Many organisms living along the coastlines synchronize their reproduction with the lunar cycle. At the time of spring tide, thousands of grass puffers (Takifugu alboplumbeus) aggregate and vigorously tremble their bodies at the water's edge to spawn. To understand the mechanisms underlying this spectacular semilunar beach spawning, we collected the hypothalamus and pituitary from male grass puffers every week for 2 months. RNA sequencing (RNA-seq) analysis identified 125 semilunar genes, including genes crucial for reproduction (e.g., gonadotropin-releasing hormone 1 [gnrh1], luteinizing hormone β subunit [lhb]) and receptors for pheromone prostaglandin E (PGE). PGE₂ is secreted into the seawater during the spawning, and its administration activates olfactory sensory neurons and triggers trembling behavior of surrounding individuals. These results suggest that PGE₂ synchronizes lunar-regulated beach-spawning behavior in grass puffers. To further explore the mechanism that regulates the lunar-synchronized transcription of semilunar genes, we searched for semilunar transcription factors. Spatial transcriptomics and multiplex fluorescent in situ hybridization showed co-localization of the semilunar transcription factor CCAAT/enhancer-binding protein δ (cebpd) and gnrh1, and cebpd induced the promoter activity of gnrh1. Taken together, our study demonstrates semilunar genes that mediate lunar-synchronized beach-spawning behavior. VIDEO ABSTRACT.

A methylbenzimidazole derivative regulates mammalian circadian rhythms by targeting Cryptochrome proteins

Background: Impairment of the circadian clock has been associated with numerous diseases, including sleep disorders and metabolic disease. Although small molecules that modulate clock function may form the basis of drug discovery of clock-related diseases, only a few compounds that selectively target core clock proteins have been identified. Three scaffolds were previously discovered as small-molecule activators of the clock protein Cryptochrome (CRY), and they have been providing powerful tools to understand and control the circadian clock system. Identifying new scaffolds will expand the possibilities of drug discovery. Methods: A methylbenzimidazole derivative TH401 identified from cell-based circadian screens was characterized. Effects of TH401 on circadian rhythms were evaluated in cellular assays. Functional assays and X-ray crystallography were used to elucidate the effects of the compound on CRY1 and CRY2 isoforms. Results: TH401 lengthened the period of circadian rhythms and stabilized both CRY1 and CRY2. The compound repressed Per2 reporter activity, which was reduced by Cry1 or Cry2 knockout and abolished by Cry1/Cry2 double knockout, indicating the dependence on CRY isoforms. Thermal shift assays showed slightly higher interaction of TH401 with CRY2 over CRY1. The crystal structure of CRY1 in complex with TH401 revealed a conformational change of the gatekeeper W399, which is involved in isoform-selectivity determination. Conclusions: The present study identified a new small molecule TH401 that targets both CRY isoforms. This compound has expanded the chemical diversity of CRY activators, and will ultimately aid in the development of therapeutics against circadian clock-related disorders.

Photoinduced Synthesis of Thiocyanates through Hydrogen Atom Transfer and One-Pot Derivatization to Isothiocyanates

Photoinduced benzylic C-H thiocyanation is described. A series of alkyl thiocyanates were efficiently obtained by using Selectfluor as the oxidant. Moreover, we accomplished the one-pot isothiocyanation following the C-H thiocyanation. The thiocyanates and isothiocyanates were applied to the divergent transformation of pharmaceuticals.

Chemical biology to dissect molecular mechanisms underlying plant circadian clocks

Circadian clocks regulate the diel rhythmic physiological activities of plants, enabling them to anticipate and adapt to day-night and seasonal changes. Genetic and biochemical approaches have suggested that transcription-translation feedback loops (TTFL) are crucial for Arabidopsis clock function. Recently, the study of chemical chronobiology has emerged as a discipline within the circadian clock field, with important and complementary discoveries from both plant and animal research. In this review, we introduce recent advances in chemical biology using small molecules to perturb plant circadian clock function through TTFL components. Studies using small molecule clock modulators have been instrumental for revealing the role of post-translational modification in the clock, or the metabolite-dependent clock input pathway, as well as for controlling clock-dependent flowering time.

Phosphorylation of RNA Polymerase II by CDKC;2 Maintains the Arabidopsis Circadian Clock Period

The circadian clock is an internal timekeeping system that governs about 24 h biological rhythms of a broad range of developmental and metabolic activities. The clocks in eukaryotes are thought to rely on lineage-specific transcriptional-translational feedback loops. However, the mechanisms underlying the basic transcriptional regulation events for clock function have not yet been fully explored. Here, through a combination of chemical biology and genetic approaches, we demonstrate that phosphorylation of RNA polymerase II by CYCLIN DEPENDENT KINASE C; 2 (CDKC;2) is required for maintaining the circadian period in Arabidopsis. Chemical screening identified BML-259, the inhibitor of mammalian CDK2/CDK5, as a compound lengthening the circadian period of Arabidopsis. Short-term BML-259 treatment resulted in decreased expression of most clock-associated genes. Development of a chemical probe followed by affinity proteomics revealed that BML-259 binds to CDKC;2. Loss-of-function mutations of cdkc;2 caused a long period phenotype. In vitro experiments demonstrated that the CDKC;2 immunocomplex phosphorylates the C-terminal domain of RNA polymerase II, and BML-259 inhibits this phosphorylation. Collectively, this study suggests that transcriptional activity maintained by CDKC;2 is required for proper period length, which is an essential feature of the circadian clock in Arabidopsis.

Melanogenic effect of dersimelagon (MT-7117), a novel oral melanocortin 1 receptor agonist

Background

The activation of melanocortin 1 receptor (MC1R) on melanocytes stimulates the production of eumelanin. A tridecapeptide α melanocyte‐stimulating hormone (αMSH) is known to induce skin pigmentation.

Objectives

We characterised the properties of a novel oral MC1R agonist dersimelagon (MT‐7117) with respect to its specific binding to MC1R, downstream signalling and eumelanin production in experimental models.

Methods

The competitive binding and production of intracellular cyclic adenosine 3′, 5′‐monophosphate in cells expressing recombinant melanocortin receptors were examined. A mouse melanoma cell line B16F1 was used for the evaluation of in vitro melanin production. The in vitro activity of MT‐7117 was determined with αMSH and [Nle⁴, D‐Phe⁷]‐αMSH (NDP‐αMSH) as reference comparators. The change of coat colour and skin pigmentation were evaluated after repeat administration of MT‐7117 by oral gavage to C57BL/6J‐A^y/+ mice and cynomolgus monkeys, respectively.

Results

MT‐7117 showed the highest affinity for human MC1R compared to the other melanocortin receptors evaluated and agonistic activity for human, cynomolgus monkey and mouse MC1R, with EC₅₀ values in the nanomolar range. In B16F1 cells, MT‐7117 increased melanin production in a concentration‐dependent manner. In vivo, MT‐7117 (≥0.3 mg/kg/day p.o.) significantly induced coat colour darkening in mice. MT‐7117 (≥1 mg/kg/day p.o.) induced significant skin pigmentation in monkeys and complete reversibility was observed after cessation of its administration.

Conclusions

MT‐7117 is a novel oral MC1R agonist that induces melanogenesis in vitro and in vivo, suggesting its potential application for the prevention of phototoxic reactions in patients with photodermatoses, such as erythropoietic protoporphyria and X‐linked protoporphyria.

In Silico Analysis and Synthesis of Nafamostat Derivatives and Evaluation of Their Anti-SARS-CoV-2 Activity

Inhibition of transmembrane serine protease 2 (TMPRSS2) is expected to block the spike protein-mediated fusion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nafamostat, a potent TMPRSS2 inhibitor as well as a candidate for anti-SARS-CoV-2 drug, possesses the same acyl substructure as camostat, but is known to have a greater antiviral effect. A unique aspect of the molecular binding of nafamostat has been recently reported to be the formation of a covalent bond between its acyl substructure and Ser441 in TMPRSS2. In this study, we investigated crucial elements that cause the difference in anti-SARS-CoV-2 activity of nafamostat and camostat. In silico analysis showed that Asp435 significantly contributes to the binding of nafamostat and camostat to TMPRSS2, while Glu299 interacts strongly only with nafamostat. The estimated binding affinity for each compound with TMPRSS2 was actually consistent with the higher activity of nafamostat; however, the evaluation of the newly synthesized nafamostat derivatives revealed that the predicted binding affinity did not correlate with their anti-SARS-CoV-2 activity measured by the cytopathic effect (CPE) inhibition assay. It was further shown that the substitution of the ester bond with amide bond in nafamostat resulted in significantly weakened anti-SARS-CoV-2 activity. These results strongly indicate that the ease of covalent bond formation with Ser441 in TMPRSS2 possibly plays a major role in the anti-SARS-CoV-2 effect of nafamostat and its derivatives.

Synthesis of deuterated γ-linolenic acid and application for biological studies: metabolic tuning and Raman imaging

γ-Linolenic acid (GLA) is reported to show tumor-selective cytotoxicity through unidentified mechanisms. Here, to assess the involvement of oxidized metabolites of GLA, we synthesized several deuterated GLAs and evaluated their metabolism and cytotoxicity towards normal human fibroblast WI-38 cells and VA-13 tumor cells generated from WI-38 by transformation with SV40 virus. Deuteration of GLA suppressed both metabolism and cytotoxicity towards WI-38 cells and increased the selectivity for VA-13 cells. Fully deuterated GLA was visualized by Raman imaging, which indicated that GLA is accumulated in intracellular lipid droplets of VA-13 cells. Our results suggest the tumor-selective cytotoxicity is due to GLA itself, not its oxidized metabolites.

Transcriptome Analysis of Arabidopsis thaliana Plants Treated with a New Compound Natolen128, Enhancing Salt Stress Tolerance

Salinity stress is a major threat to agriculture and global food security. Chemical priming is a promising approach to improving salinity stress tolerance in plants. To identify small molecules with the capacity to enhance salinity stress tolerance in plants, chemical screening was performed using Arabidopsis thaliana. We screened 6400 compounds from the Nagoya University Institute of Transformative Bio-Molecule (ITbM) chemical library and identified one compound, Natolen128, that enhanced salinity-stress tolerance. Furthermore, we isolated a negative compound of Natolen128, namely Necolen124, that did not enhance salinity stress tolerance, though it has a similar chemical structure to Natolen128. We conducted a transcriptomic analysis of Natolen128 and Necolen124 to investigate how Natolen128 enhances high-salinity stress tolerance. Our data indicated that the expression levels of 330 genes were upregulated by Natolen128 treatment compared with that of Necolen124. Treatment with Natolen128 increased expression of hypoxia-responsive genes including ethylene biosynthetic enzymes and PHYTOGLOBIN, which modulate accumulation of nitric oxide (NO) level. NO was slightly increased in plants treated with Natolen128. These results suggest that Natolen128 may regulate NO accumulation and thus, improve salinity stress tolerance in A. thaliana.

Sesame lignans suppress age-related disorders of the kidney in mice

OBJECTIVE

Sesamin is a functional ingredient in sesame (Sesamum indicum) seeds and has many physiological effects. This study investigated whether sesame lignans, sesamin and episesamin (1:1), can suppress age-related disorders of the kidney.

MATERIALS AND METHODS

Twenty-month-old mice were divided into three groups, and each group received a regular diet (O-C), diet containing sesame lignans (O-SE), and diet containing sesame lignans and α-tocopherol (VE; O-SE+VE), respectively, for 5 months. Six-month-old young mice (Y-C) were compared to the older mice.

RESULTS

Renal lipofuscin deposition was increased in the O-C group compared to that in the Y-C group and its deposition with aging was significantly decreased in both O-SE and O-SE+VE groups. Plasma blood urea nitrogen levels in the O-C group increased compared to those in the Y-C group; however, those in both O-SE and O-SE+VE groups did not differ from those in the Y-C group. The number of podocytes in the O-C group decreased compared to that in the Y-C group and this effect was attenuated in the O-SE and O-SE+VE groups. The effect was strongest in the O-SE+VE group. Histological examinations showed that glomerular hypertrophy accompanied by mesangial hyperplasia and renal tubular degeneration was less severe in the O-SE and O-SE+VE groups than in the O-C group. Moreover, age-related increases in the mRNA expression of NADPH oxidase- and inflammation-related genes, including p67phox, p40phox, TNFα, and IL-6, in the kidney were suppressed in the O-SE and O-SE+VE groups.

CONCLUSIONS

Sesame lignans might be useful to suppress age-related kidney disorders, and these effects could be enhanced with VE.

Antihypertensive drug valsartan as a novel BDK inhibitor

Catabolism of branched-chain amino acids (BCAAs) is affected by various physiological conditions and its abnormality is associated with glucose metabolism, heart disease, and neurological dysfunction. The first two steps of the BCAA metabolic pathway are common to the three BCAAs (leucine, isoleucine, and valine). The second step is an irreversible rate-limited reaction catalyzed by branched-chain α-keto acid dehydrogenase (BCKDH), which is bound to a specific kinase, BCKDH kinase (BDK), and inactivated by phosphorylation. Here, we investigated potential new BDK inhibitors and discovered valsartan, an angiotensin II type 1 receptor (AT1R) blocker, as a new BDK inhibitor. BCKDH phosphorylation and the BCKDH-BDK interaction were inhibited by valsartan in vitro. Valsartan administration in rats resulted in increased BCKDH activity by decreasing the dephosphorylated level of BCKDH complex, bound forms of BDK from BCKDH complex as well as decreased plasma BCAA concentrations. Valsartan is a novel BDK inhibitor that competes with ATP, via a different mechanism from allosteric inhibitors. The BDK inhibitor has been shown to preserve cardiac function in pressure overload-induced heart failure mice and to attenuate insulin resistance in obese mice. Our findings suggest that valsartan is a potent seed compound for developing a powerful BDK inhibitor and useful medication for treating heart failure and metabolic diseases with suppressed BCAA catabolism.

Identification of a Devernalization Inducer by Chemical Screening Approaches in Arabidopsis thaliana

Vernalization is the promotion of flowering after prolonged exposure to cold. In Arabidopsis thaliana, vernalization induces epigenetic silencing of the floral repressor gene FLOWERING LOCUS C (FLC). The repressive epigenetic mark trimethylation of lysine 27 on histone H3 proteins (H3K27me3) is a critical contributor to the epigenetic silencing of FLC. Interestingly, the deposited H3K27me3 in the FLC locus can be erased by short-term high-temperature treatment. This is referred to as devernalization. In this study, we identified a novel chemical compound, 4-Isoxazolecarboxylic acid, 3,5-dimethyl-2-(4-fluorophenyl)-4-isoxazole carboxylic acid 1-methyl-2-oxoethyl ester named as DEVERNALIZER01 (DVR01), which induces devernalization in Arabidopsis seedlings, by an FLC-luciferase reporter-based high-throughput screening assay. DVR01 decreased the amount of H3K27me3 in the FLC locus in vernalized plants, resulting in the upregulation of FLC in the whole plant, including the vasculature and meristem, where FLC represses floral induction genes. We also showed that a 2-week treatment with DVR01 reverted plants with a vernalized status back to a fully non-vernalized status. Collectively, this study provides a novel structure of DVR01, which modulates devernalization via demethylation of H3K27me3 in the FLC locus.

Photopharmacological Manipulation of Mammalian CRY1 for Regulation of the Circadian Clock

CRY1 and CRY2 proteins are highly conserved components of the circadian clock that controls daily physiological rhythms. Disruption of CRY functions are related to many diseases, including circadian sleep phase disorder. Development of isoform-selective and spatiotemporally controllable tools will facilitate the understanding of shared and distinct functions of CRY1 and CRY2. Here, we developed CRY1-selective compounds that enable light-dependent manipulation of the circadian clock. From phenotypic chemical screening in human cells, we identified benzophenone derivatives that lengthened the circadian period. These compounds selectively interacted with the CRY1 photolyase homology region, resulting in activation of CRY1 but not CRY2. The benzophenone moiety rearranged a CRY1 region called the “lid loop” located outside of the compound-binding pocket and formed a unique interaction with Phe409 in the lid loop. Manipulation of this key interaction was achieved by rationally designed replacement of the benzophenone with a switchable azobenzene moiety whose cis–trans isomerization can be controlled by light. The metastable cis form exhibited sufficiently high half-life in aqueous solutions and structurally mimicked the benzophenone unit, enabling reversible period regulation over days by cellular irradiation with visible light. This study revealed an unprecedented role of the lid loop in CRY-compound interaction and paves the way for spatiotemporal regulation of CRY1 activity by photopharmacology for molecular understanding of CRY1-dependent functions in health and disease.

Efficacy of cardiac rehabilitation with motion assistance from wearable cyborg hybrid assistive limb in patients with chronic heart failure: a randomized controlled trial

Background

Recent Cochrane Systematic Review suggested that the participation in cardiac rehabilitation is associated with approximately 20% lower cardiovascular mortality and morbidity. Exercise therapy is the key component of cardiac rehabilitation programs. In recent years, innovative technologies have been introduced into the field of rehabilitation, and a typical example is the wearable cyborg Hybrid Assistive Limb (HAL). The wearable cyborg HAL provides motion assistance based on detection of bioelectrical signals on the skin surface when muscle forces are generated. The lumbar-type HAL is expected to expand the therapeutic options for severe cardiac patients who have difficulty in performing usual cardiac rehabilitation programs, such as bicycle pedaling or walking.

Purpose

We aim to compare the efficacy of exercise therapy performed with motion assistance from a lumbar-type HAL versus conventional training (sit-to-stand exercise without HAL) in patients with chronic heart failure.

Methods

This clinical trial is a randomized, non-blinded, and controlled study. Twenty-eight heart failure patients (73.1±13.8 years) who have difficulty in walking at the usual walking speed of healthy subjects were randomly assigned to 2 groups (HAL group or control group) with a 1:1 allocation ratio and performed sit-to stand exercise either with HAL or without HAL for 5 to 30 minutes once a day, and 6 to 10 days during the study period. The brain natriuretic peptide (BNP), isometric knee extensor strength, standing ability (30-seconds chair-stand test: CS-30), short physical performance battery (SPPB) and 6-minute walking distance (6MWD) were measured before and after the completion of cardiac rehabilitation. Cardiac events such as death, re-hospitalization, myocardial infarction and worsening of angina pectoris and heart failure during 1 year after discharge were evaluated.

Results

There was no significant difference in the number of days of exercise therapy between the two groups. BNP, SPPB and 6MWD were improved in both groups. In the HAL group, the isometric knee extensor strength (0.29±0.11 vs 0.35±0.11 kgf/kg, p=0.003) significantly improved and CS-30 (5.5±5.1 vs 8.2±5.3, p=0.054) tended to improve. However, in the control group, either the isometric knee extensor strength (0.35±0.11 vs 0.36±0.14 kgf/kg, p=0.424) or CS-30 (6.0±4.3 vs 9.2±6.2, p=0.075) did not significantly change. HAL group showed significantly more improvement in the isometric knee extensor strength than control group (p=0.045). Cardiac events occurred in 20% in the HAL group and 43% in the control group.

Conclusion

The improvement in isometric knee extensor strength with the assistance from lumbar-type HAL suggests that exercise therapy using this device may be useful in chronic heart failure patients with flail or sarcopenia, a strong poor prognostic factor in these patients.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Science, and Culture of Japan (JSPS KAKENHI grant number JP17K09485) and funded by the ImPACT Program of the Council for Science, Technology and Innovation (Cabinet Office, Government of Japan) (grant number 2017-PM05-03-01).

Impact of coronary plaque characteristics on periprocedural myocardial injury after elective percutaneous coronary intervention -MDCT and CMR analysis-

Background

Percutaneous coronary intervention (PCI) is often complicated by periprocedural myocardial injury (PMI) manifested by elevated cardiac biomarkers. The occurrence of PMI has been shown to be associated with worse clinical outcome over short- and long-term.

Purpose

We performed multidetector computed tomography (MDCT) and cardiac magnetic resonance imaging (CMR) to evaluate the relationship between culprit plaque characteristics and PMI.

Methods

A total of 90 patients who underwent elective PCI were underwent CMR and multidetector coronary tomography before PCI. The high intensity plaque (HIP) on CMR was defined as a coronary plaque to myocardium signal intensity ratio (PMR) of &gt;1.4. The plaque characteristics and the presence of napkin-ring sign (NRS) were analyzed on MDCT. PMI was defined as an increase in cardiac Troponin T levels to more than 5 times the upper limit of normal at 24 h after PCI. Patients were divided into 2 groups according to the presence (Group I, n=26) or absence (Group II, n=64) of PMI.

Results

Spotty calcification, positive remodeling, low attenuation plaque and NRS on MDCT were significantly more observed in Group I than in Group II. HIP on CMR was significantly more observed in Group I than in Group II. In the multivariable logistic regression analysis, the presence of NRS and HIP were significantly independent predictors of PMI (odds ratio (OR) 4.82, 95% confidence interval 1.13–20.60, P=0.034 and OR 3.66, 95% CI 1.09–12.30, P=0.036, respectively). Moreover, for prediction of PMI, NRS and HIP showed a high positive predictive value of 81%, and their absence showed a high negative predictive value of 91%.

Conclusions

MDCT and CMR may play an important role in detecting which lesions are high risks for myocardial necrosis after PCI in elective coronary stenting.

Funding Acknowledgement

Type of funding source: None

Association of coronary high-intensity plaque on T1-weighted magnetic resonance imaging and circulating malondialdehyde-modified low-density lipoprotein levels with cardiac events

Background

Although elevated oxidized low-density lipoprotein could play critical roles in vulnerable plaque, there are no studies that compared coronary high-intensity plaque (HIP) on non-contrast T1-weighted magnetic resonance imaging (T1WI_MRI) and circulating malondialdehyde-modified low-density lipoprotein (MDA-LDL) levels for the prediction of cardiac events.

Methods and results

A total of 139 patients with coronary artery stenosis (&gt;70%) were examined with non-contrast T1WI using a 1.5-T MRI (HIP: n=63, non-HIP: n=76). Scheduled percutaneous coronary intervention (PCI) for culprit lesions was performed within 48 h after MRI. HIP was defined as a signal intensity of coronary plaque to cardiac muscle ratio (PMR) of ≥1.4. At admission, circulating levels of MDA-LDL and other lipid-related markers were measured. We evaluated the subsequent cardiac events, which were defined as major adverse cardiac events (MACE; cardiac death, myocardial infarction, and/or ischemia-driven PCI) during follow-up periods (5.6±1.3 years). Circulating MDA-LDL levels were significantly higher in patients with HIP than in those without HIP (p&lt;0.0001). MDA-LDL levels were significantly correlated with PMR (r=0.490, p&lt;0.0001). In multivariable logistic regression analysis, MDA-LDL levels were independently associated with the presence of HIP (OR 1.05; 95% CI, 1.02–1.08, p&lt;0.0001). The incidence of MACE was significantly higher in patients with HIP (27%) than in those without HIP (5%; p=0.011 by the log-rank test). In the multivariable Cox proportional hazard analysis, the MDA-LDL levels (HR 1.03; 95% CI:1.01–1.05, p=0.007) and PMR (HR 2.39; 95% CI:1.19–4.65, p=0.016) were significantly associated with MACE. For MACE prediction, the C-statistic values for MDA-LDL, PMR, and PMR+MDA-LDL were 0.724, 0.791, and 0.800, respectively. Compared with MDA-LDL alone, the addition of PMR to MDA-LDL increased the net reclassification improvement by 0.78 (p=0.012).

Conclusions

MDA-LDL levels might be associated with the presence of HIP in patients with coronary artery disease. Furthermore, adding PMR to MDA-LDL levels markedly improved MACE prediction.

Funding Acknowledgement

Type of funding source: None

Pulmonary vein isolation for atrial fibrillation patients with reduced left ventricular ejection fraction

 

Background/Introduction Pulmonary vein isolation (PVI) is a cornerstone of curable treatment for atrial fibrillation (AF). Left ventricular (LV) ejection fraction (EF) occasionally improves after PVI in AF patients with reduced LVEF (rEF), the mechanism of which is not fully understood. CASTLE-AF trial have demonstrated that PVI with radiofrequency (RF) catheter for AF patients with rEF can reduce their mortality and heart failure. Nevertheless there are limited data about the clinical outcome of the PVI for patients with impaired LV function.

Purpose

This study was to evaluate the efficacy of PVI and improvement of LVEF after the procedure in AF patients with rEF.

Methods

A total of 2709 consecutive AF patients (age 65±39 y/o, male 67%) underwent their first PVI with cryoballoon or RF catheter in our facility from April 2014 to March 2019, and retrospectively analyzed. All the patients underwent echocardiogram before and half to one year after the procedure. Patients with LVEF under 40% before the PVI were selected (n=111) and divided into two groups based on whether there were specific etiologies of LV function impairment (group A) or not (group B).

Results

There were no significant difference in mean LVEF between group A (n=40) and group B (n=71) (32±6% vs 33±6%, p=0.12). The major etiology of rEF in group A were old myocardial infarction (n=20, 18%), hypertensive heart disease (n=6, 5.4%), and dilated cardiomyopathy (n=5, 4.5%). After mean follow-up of 2.7 years, there were no significant difference in clinical outcome after the procedure between two groups (1-year Kaplan–Meier event rate estimates; 72.2% vs 72.9%; p=0.85). The change amounts of LVEF after the PVI were significantly higher in group B (20±14%) compared to group A (2±10%) (p&lt;0.001). Multivariable Cox regression analysis revealed that age was the independent significant predictors of EF improvement over 10% in group B (p=0.048).

Conclusions

In AF patients with reduced LVEF, there were no significant difference in efficacy of PVI between those who have specific etiologies of LV function impairment other than AF and who have not. The improvement of LVEF after PVI was significantly larger in patients without specific etiologies compared to those with.

Funding Acknowledgement

Type of funding source: None

Isoform-selective regulation of mammalian cryptochromes

CRY1 and CRY2 are essential components of the circadian clock controlling daily physiological rhythms. Accumulating evidences indicate distinct roles of these highly homologous proteins, in addition to redundant functions. Therefore, the development of isoform-selective compounds represents an effective approach towards understanding the similarities and differences of CRY1 and CRY2 by controlling each isoform individually. We conducted phenotypic screenings of circadian clock modulators, and identified KL101 and TH301 that selectively stabilize CRY1 and CRY2, respectively. Crystal structures of CRY-compound complexes revealed conservation of compound-binding sites between CRY1 and CRY2. We further discovered a unique mechanism underlying compound selectivity in which the disordered C-terminal region outside the pocket was required for the differential effects of KL101 and TH301 against CRY isoforms. By using these compounds, we found a new role of CRY1 and CRY2 as enhancers of brown adipocyte differentiation, providing the basis of CRY-mediated regulation of energy expenditure.

3,4-Dibromo-7-Azaindole Modulates Arabidopsis Circadian Clock by Inhibiting Casein Kinase 1 Activity

The circadian clock is a timekeeping system for regulation of numerous biological daily rhythms. One characteristic of the circadian clock is that period length remains relatively constant in spite of environmental fluctuations, such as temperature change. Here, using the curated collection of in-house small molecule chemical library (ITbM chemical library), we show that small molecule 3,4-dibromo-7-azaindole (B-AZ) lengthened the circadian period of Arabidopsis thaliana (Arabidopsis). B-AZ has not previously been reported to have any biological and biochemical activities. Target identification can elucidate the mode of action of small molecules, but we were unable to make a molecular probe of B-AZ for target identification. Instead, we performed other analysis, gene expression profiling that potentially reveals mode of action of molecules. Short-term treatment of B-AZ decreased the expression of four dawn- and morning-phased clock-associated genes, CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1), LATE ELONGATED HYPOCOTYL (LHY), PSEUDO-RESPONSE REGULATOR 9 (PRR9) and PRR7. Consistently, amounts of PRR5 and TIMING OF CAB EXPRESSION 1 (TOC1) proteins, transcriptional repressors of CCA1, LHY, PRR9 and PRR7 were increased upon B-AZ treatment. B-AZ inhibited Casein Kinase 1 family (CK1) that phosphorylates PRR5 and TOC1 for targeted degradation. A docking study and molecular dynamics simulation suggested that B-AZ interacts with the ATP-binding pocket of human CK1 delta, whose amino acid sequences are highly similar to those of Arabidopsis CK1. B-AZ-induced period-lengthening effect was attenuated in prr5 toc1 mutants. Collectively, this study provides a novel and simple structure CK1 inhibitor that modulates circadian clock via accumulation of PRR5 and TOC1.

P3098Association with coronary high-intensity plaque on T1-weighted magnetic resonance imaging and circulating levels of malondialdehyde-modified low-density lipoprotein

Objectives

This study aimed to evaluate the association with coronary high-intensity plaque (HIP) on non-contrast T1-weighted magnetic resonance imaging (T1WI) and circulating levels of malondialdehyde-modified low-density lipoprotein (MDA-LDL).

Methods

A total of 139 patients with coronary artery stenosis (>70%) were imaged with non-contrast T1WI by using a 1.5-T magnetic resonance system (HIP: n=60, non-HIP: n=79). HIP was defined as a signal intensity of coronary plaque to cardiac muscle ratio (PMR) of ≥1.4. At admission, circulating levels of MDA-LDL and other lipid-related markers (triglyceride, HDL, LDL, Lp(a), RLP-C, and EPA/AA) were measured.

Results

Circulating levels of MDA-LDL (p=0.001) and LDL (p=0.041) were significantly higher in patients with HIP than those without, whereas the other lipid-related markers were not significantly different between both groups. In multivariable logistic regression analysis, MDA-LDL levels were independently associated with the presence of HIP (OR 1.03; 95% CI, 1.00–1.06, p=0.015) after adjusting for cofounding factors (age, sex, triglyceride, LDL, Lp(a), RLP-C, and EPA/AA). The optimal MDA-LDL threshold for predicting coronary HIP was 90.4 U/L, identified by the receiver operating characteristic curve.

Conclusion

MDA-LDL levels might be associated with the presence of HIP in patients with coronary artery disease.

P737Endothelial ERK2/thromboxane receptor pathway induces endothelial dysfunction, insulin resistance and steatohepatosis through superoxide with high fat high sucrose diet

Introduction

Metabolic syndrome (MetS) is well known as the risk of cardiovascular diseases associated with endothelial dysfunction and induces steatohepatosis. Insulin resistance is a major character of MetS, which affects intracellular signaling pathways and endothelial function. Extracellular signal-regulated kinase (ERK) is a major component of insulin signal and many of vasoactive peptides, which were released in MetS, can activate it in endothelium. However, the role of endothelial ERK in nitric oxide (NO) bioactivity in MetS in in vivo has been unknown.

Purpose

The aim of this study is to clarify the role of endothelial ERK2 on NO bioactivity in mice model of MetS.

Methods and results

We created endothelial specific ERK2 knock out mice (EE2KO) crossing Tie2-Cre mice and ERK2 flox mice and fed them with normal or high-fat/high-sucrose diet (HFHSD) for 24 weeks. Serum glucose and insulin levels and HOMA-IR were lowered in EE2KO with HFHSD without changing body weight. In wild type mice (WT) with HFHSD, nonalcoholic fatty liver disease (NAFLD) activity score, fibrosis score and serum ALT level were increased, all of which were blunted in EE2KO. EE2KO with HFHSD lowered systolic blood pressure (WT: 123.7±5.83 mmHg, EE2KO: 101.4±3.66 mmHg, P<0.01, N=8) without changing heart rate, which was increased to the same levels with L-NAME, an endothelial NO synthase inhibitor, in both groups. Serum NO levels measured with serum nitrite/nitrate concentrations were increased in EE2KO with HFHSD (WT: 23.10±3.74 μmol/l, EE2KO: 41.71±6.73 μmol/l, P<0.05, N=12). Endothelial function was assessed with the isometric tension measurement of aortic rings with acetylcholine (ACh). ACh-induced relaxation was improved in EE2KO with HFHSD. Superoxide production of aorta from EE2KO was lowered than WT with HFHSD in dihydroethidium (DHE) staining. S18886, an antagonist of the thromboxane A2-prostanoid (TP) receptor, decreased superoxide production of aorta in DHE staining resulting in improving endothelial function in the isometric tension measurement of aortic rings. Oral administrations of S18886 decreased systolic blood pressure, serum fasting glucose and insulin levels, and surprisingly improved steatohepatosis by decreasing NAFLD activity score and fibrosis score.

Relaxation of aortic rings with ACh

Conclusions

Endothelial ERK2/TP receptor pathway increases superoxide production and decreased NO bioactivity, resulting in deteriorating endothelial function, insulin resistance and steatohepatosis, which were improved by antagonist of the TP receptor in mice model of MetS. The present study indicates that ERK2/TP pathway could be a therapeutic target for complications of MetS.