Atrial tachyarrhythmia prevention by Shensong Yangxin after catheter ablation for persistent atrial fibrillation: the SS-AFRF trial.

BACKGROUND AND AIMS: Despite advances in technology and techniques, the recurrence rate of persistent atrial fibrillation (AF) following catheter ablation remains high. The Shensong Yangxin (SSYX) capsule, a renowned traditional Chinese medicine formula, is used in the treatment of cardiac arrhythmias. This trial aimed to investigate whether the SSYX can improve clinical outcomes in patients who have undergone catheter ablation for persistent AF. METHODS: A multi-centre, randomized, double-blind, placebo-controlled clinical trial was conducted at 66 centres in China among 920 patients with persistent AF undergoing first ablation. Participants were randomized to oral SSYX, 1.6 g (.4 g/granule) thrice daily (n = 460), or matched placebo (n = 460) for 12 months. The primary endpoint was recurrent atrial tachyarrhythmias lasting for ≥30 s following a blanking period of 3 months. Secondary endpoints included time to first documented atrial tachyarrhythmias, AF burden, cardioversion, stroke/systemic embolism, changes in echocardiographic parameters, and quality-of-life (QoL) score. Analyses were performed according to the intention-to-treat principle. RESULTS: A total of 920 patients underwent randomization (460 assigned to SSYX group and 460 assigned to placebo group). During the follow-up of 12 months, patients assigned to SSYX had a higher event-free rate from recurrent atrial tachyarrhythmias when compared with the placebo group (12-month Kaplan-Meier event-free rate estimates, 85.5% and 77.7%, respectively; hazard ratio, .6; 95% confidence interval .4-.8; P = .001). Patients assigned to receive SSYX had a better QoL score at 12 months compared to those randomized to placebo. There was no significant difference in the incidence of serious adverse events between the two groups. CONCLUSIONS: Treatment with SSYX following radiofrequency catheter ablation for persistent AF reduced the incidence of recurrent atrial tachyarrhythmias and led to clinically significant improvements in QoL during a 12-month follow-up in a Chinese population.

Silicon-Containing Thiol-Specific Bioconjugating Reagent.

A new bioconjugation reagent containing silicon has been developed for the selective reaction with thiols. The inclusion of silicon significantly improves chemoselectivity and suppresses retro processes, thereby exceeding the capabilities of traditional reagents. The method is versatile and compatible with a broad range of thiols and unsaturated carbonyl compounds and yields moderate to high results. These reactions can be conducted under biocompatible conditions, thereby making them suitable for protein bioconjugation. The resulting conjugates display good stability in the presence of various biomolecules, which suggests their potential application for the synthesis of antibody-drug conjugates. Furthermore, the presence of a silicon moiety within the conjugated products opens up new avenues for drug release and bridging inorganics with other disciplines. This new class of silicon-containing thiol-specific bioconjugation reagents has significant implications for researchers working in bioanalytical science and medicinal chemistry and leads to innovative opportunities for advancing the field of bioconjugation research and medicinal chemistry.

Recent Advances in Alkenyl sp2 C-H and C-F Bond Functionalizations: Scope, Mechanism, and Applications.

Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, and advanced materials. Significant efforts have been made toward the development of new and practical methods to access this important class of compounds by selectively activating the alkenyl C(sp2)-H bonds in recent years. In this comprehensive review, we describe the state-of-the-art strategies for the direct functionalization of alkenyl sp2 C-H and C-F bonds until June 2022. Moreover, metal-free, photoredox, and electrochemical strategies are also covered. For clarity, this review has been divided into two parts; the first part focuses on currently available alkenyl sp2 C-H functionalization methods using different alkene derivatives as the starting materials, and the second part describes the alkenyl sp2 C-F bond functionalization using easily accessible gem-difluoroalkenes as the starting material. This review includes the scope, limitations, mechanistic studies, stereoselective control (using directing groups as well as metal-migration strategies), and their applications to complex molecule synthesis where appropriate. Overall, this comprehensive review aims to document the considerable advancements, current status, and emerging work by critically summarizing the contributions of researchers working in this fascinating area and is expected to stimulate novel, innovative, and broadly applicable strategies for alkenyl sp2 C-H and C-F bond functionalizations in the coming years.

Ionogels: recent advances in design, material properties and emerging biomedical applications.

Ionic liquid (IL)-based gels (ionogels) have received considerable attention due to their unique advantages in ionic conductivity and their biphasic liquid-solid phase property. In ionogels, the negligibly volatile ionic liquid is retained in the interconnected 3D pore structure. On the basis of these physical features as well as the chemical properties of well-chosen ILs, there is emerging interest in the anti-bacterial and biocompatibility aspects. In this review, the recent achievements of ionogels for biomedical applications are summarized and discussed. Following a brief introduction of the various types of ILs and their key physicochemical and biological properties, the design strategies and fabrication methods of ionogels are presented by means of different confining networks. These sophisticated ionogels with diverse functions, aimed at biomedical applications, are further classified into several active domains, including wearable strain sensors, therapeutic delivery systems, wound healing and biochemical detections. Finally, the challenges and possible strategies for the design of future ionogels by integrating materials science with a biological interface are proposed.

The Effect of Bacterial AHL on the Cyclic Adenosine Monophosphate Content in Plants According to High-Performance Liquid Chromatography.

Cyclic adenosine monophosphate (cAMP) is an important second messenger in cells, mediating various stimulation signals such as the growth and development of organisms and stress and participating in regulating various biological processes of cells. This article explores the quantitative determination of cAMP in plants using High-Performance Liquid Chromatography (HPLC) and applies this method to analyzing the changes in cAMP content during the process of plant response to the bacterial quorum sensing signal N-acyl homoserine lactone (AHL). Research has shown that the optimal detection conditions for HPLC are as follows: the chromatographic column is Venusil MP C18 (2), the mobile phase is methanol-water (0.1% trifluoroacetic acid) (v:v, 10:90), the detection wavelength is 259 nm, the column temperature is 35 °C, and the flow rate is 0.8 mL/min. The precision of the standard sample of this method is 98.21%, the precision of the sample is 98.87%, and the recovery rate is 101.067%. The optimal extraction conditions for cAMP in Arabidopsis are to use 15% methanol ultrasonic extraction for 10 min, followed by a 40 °C water bath for 4 h. Bacterial AHL signal processing can significantly stimulate an increase in cAMP levels in Arabidopsis leaves and roots. The establishment of HPLC detection methods for the cAMP content in plants is of great significance for in-depth research on the signal transduction mechanisms of plant-bacterial interactions.

P(V)-Promoted Rh-Catalyzed Highly Regioselective Hydroformylation of Styrenes under Mild Conditions.

Hydroformylation of olefins is widely used in the chemical industry due to its versatility and the ability to produce valuable aldehydes with 100% atom economy. Herein, a hybrid phosphate promoter was found to efficiently promote rhodium-catalyzed hydroformylation of styrenes under remarkably mild conditions with high regioselectivities. Preliminary mechanistic studies revealed that the weak coordination between the Rhodium and the P=O double bond of this pentavalent phosphate likely induced exceptional reactivity and high ratios of branched aldehydes to linear products.

Robust Catalytic SEAr H/D Exchange of Arenes with D2O: Metal-Free Deuteration of Natural Complexes and Drugs.

A catalytic metal-free approach for the H/D exchange in aromatic compounds using D2O as the terminal deuterating reagent has been developed. This metal-free protocol employs a triaryl carbenium as the mediator and showcases a wide applicability in the late-stage deuteration of various natural products and small-molecule drugs. Gram-scale deuteration was successfully demonstrated with ß-Estradiol, highlighting the method's practicability. Detailed mechanistic insights, supported by DFT calculations, unveiled the essential role of in-situ generated acidic species in this electrophilic aromatic substitution process. This newly developed method offers a sustainable and versatile alternative to traditional metal-catalyzed H/D exchange techniques, addressing challenges such as the use of expensive metals, impurity formation, and the necessity for residual metal removal from the final products.

Triaryl Carbenium Ion Pair Mediated Electrocatalytic Benzylic C-H Oxygenation in Air.

The selective oxidation of benzylic C-H bonds is a pivotal transformation in organic synthesis. Undoubtedly, achieving efficient and highly selective aerobic oxidation of methylarenes to benzaldehydes has been highly challenging due to the propensity of benzaldehyde to undergo overoxidation under typical aerobic conditions. Herein, we propose an innovative approach to address this issue by leveraging electrocatalytic processes, facilitated by ion-pair mediators [Ph3C]+[B(C6F5)4]-. By harnessing the power of electrochemistry, we successfully demonstrated the effectiveness of our strategy, which enables the selective oxidation of benzylic C-H bonds in benzylic molecules and toluene derivatives. Notably, our approach exhibited high efficiency, excellent selectivity, and compatibility with various functional groups, underscoring the broad applicability of our methodology.

Recent advances in ligand-enabled palladium-catalyzed divergent synthesis.

Developing efficient and straightforward strategies to rapidly construct structurally distinct and diverse organic molecules is one of the most fundamental tasks in organic synthesis, drug discovery and materials science. In recent years, divergent synthesis of organic functional molecules from the same starting materials has attracted significant attention and has been recognized as an efficient and powerful strategy. To achieve this objective, the proper adjustment of reaction conditions, such as catalysts, solvents, ligands, etc., is required. In this review, we summarized the recent efforts in chemo-, regio- and stereodivergent reactions involving acyclic and cyclic systems catalyzed by palladium complexes. Meanwhile, the reaction types, including carbonylative reactions, coupling reactions and cycloaddition reactions, as well as the probable mechanism have also been highlighted in detail.

Thiol-Specific Silicon-Containing Conjugating Reagent: ß-Silyl Alkynyl Carbonyl Compounds.

Site-specific modification of thiol-containing biomolecules has been recognized as a versatile and powerful strategy for probing our biological systems and discovering novel therapeutics. The addition of lipophilic silicon moiety opens up new avenues for multi-disciplinary research with broad applications in both the medicinal and material sciences. However, adhering to the strict biocompatibility requirements, and achieving the introduction of labile silicon handle and high chemo-selectivity have been formidable. In this paper, we report silicon-based conjugating reagents including ß-trialkylsilyl and silyl ether-tethered alkynones that selectively react with thiols under physiological conditions. The pH-neutral, metal-free and additive-free reaction yields stable products with broad substrate compatibility and full retention of silicon handles in most cases. Besides simple aliphatic and aromatic thiols, this approach is applicable in the labeling of thiols present in proteins, sugars and payloads, thereby expanding the toolbox of thiol conjugation.

Cellular messengers involved in the inhibition of the Arabidopsis primary root growth by bacterial quorum-sensing signal N-decanoyl-L-homoserine lactone.

BACKGROUND: N-acyl-homoserine lactones (AHLs) are used as quorum-sensing signals by Gram-negative bacteria, but they can also affect plant growth and disease resistance. N-decanoyl-L-homoserine lactone (C10-HSL) is an AHL that has been shown to inhibit primary root growth in Arabidopsis, but the mechanisms underlying its effects on root architecture are unclear. Here, we investigated the signaling components involved in C10-HSL-mediated inhibition of primary root growth in Arabidopsis, and their interplay, using pharmacological, physiological, and genetic approaches. RESULTS: Treatment with C10-HSL triggered a transient and immediate increase in the concentrations of cytosolic free Ca2+ and reactive oxygen species (ROS), increased the activity of mitogen-activated protein kinase 6 (MPK6), and induced nitric oxide (NO) production in Arabidopsis roots. Inhibitors of Ca2+ channels significantly alleviated the inhibitory effect of C10-HSL on primary root growth and reduced the amounts of ROS and NO generated in response to C10-HSL. Inhibition or scavenging of ROS and NO neutralized the inhibitory effect of C10-HSL on primary root growth. In terms of primary root growth, the respiratory burst oxidase homolog mutants and a NO synthase mutant were less sensitive to C10-HSL than wild type. Activation of MPKs, especially MPK6, was required for C10-HSL to inhibit primary root growth. The mpk6 mutant showed reduced sensitivity of primary root growth to C10-HSL, suggesting that MPK6 plays a key role in the inhibition of primary root growth by C10-HSL. CONCLUSION: Our results indicate that MPK6 acts downstream of ROS and upstream of NO in the response to C10-HSL. Our data also suggest that Ca2+, ROS, MPK6, and NO are all involved in the response to C10-HSL, and may participate in the cascade leading to C10-HSL-inhibited primary root growth in Arabidopsis.

Fluoride Anion Catalyzed Mukaiyama-Aldol Reaction: Rapid Access to α-Fluoro-ß-hydroxy Esters.

The Mukaiyama-aldol reaction is probably one of the most efficient strategies to prepare synthetically useful ß-hydroxy carbonyl compounds. However, only several reported methods were concerned with the accesses to α-fluoro-ß-hydroxy esters. Herein, we report a protocol for a fluoride anion-mediated Mukaiyama aldol reaction with low catalytic loading in a short reaction time to incorporate fluorine at the α position into ß-hydroxy esters. The method shows good functional-group tolerance and scale-up potential, moreover, is applicable to the late-stage modification of natural products and small molecular drugs.

XiaoEr LianHuaQinqGan alleviates viral pneumonia in mice infected by influenza A and respiratory syncytial viruses.

CONTEXT: Xiaoer lianhuaqinqgan (XELH), developed based on Lianhua Qingwen (LHQW) prescription, contains 13 traditional Chinese medicines. It has completed the investigational new drug application to treat respiratory viral infections in children in China. OBJECTIVE: This study demonstrates the pharmacological effects of XELH against viral pneumonia. MATERIALS AND METHODS: The antiviral and anti-inflammatory effects of XELH were investigated in vitro using H3N2-infected A549 and LPS-stimulated RAW264.7 cells and in vivo using BALB/c mice models of influenza A virus (H3N2) and respiratory syncytial virus (RSV)-infection. Mice were divided into 7 groups (n = 20): Control, Model, LHQW (0.5 g/kg), XELH-low (2 g/kg), XELH-medium (4 g/kg), XELH-high (8 g/kg), and positive drug (20 mg/kg oseltamivir or 60 mg/kg ribavirin) groups. The anti-inflammatory effects of XELH were tested in a rat model of LPS-induced fever and a mouse model of xylene-induced ear edoema. RESULTS: In vitro, XELH inhibited the pro-inflammatory cytokines and replication of H1N1, H3N2, H1N1, FluB, H9N2, H6N2, H7N3, RSV, and HCoV-229E viruses, with (IC50 47.4, 114, 79, 250, 99.2, 170, 79, 62.5, and 93 µg/mL, respectively). In vivo, XELH reduced weight loss and lung index, inhibited viral replication and macrophage M1 polarization, ameliorated lung damage, decreased inflammatory cell infiltration and pro-inflammatory cytokines expression in lung tissues, and increased the CD4+/CD8+ ratio. XELH inhibited LPS-induced fever in rats and xylene-induced ear edoema in mice. CONCLUSION: XELH efficacy partially depends on integrated immunoregulatory effects. XELH is a promising therapeutic option against childhood respiratory viral infections.

Jinlida granules ameliorate the high-fat-diet induced liver injury in mice by antagonising hepatocytes pyroptosis.

CONTEXT: Jinlida (JLD) as a traditional Chinese medicine formula has been used to treat type 2 diabetes mellitus (T2DM) and studies have shown its anti-obesity effect. OBJECTIVE: To investigate the therapeutic effects of JLD in a mouse model of non-alcoholic fatty liver (NAFL). MATERIALS AND METHODS: C57BL/6J mice were divided into three groups and fed a low-diet diet (LFD), high-fat diet (HFD), or HFD + JLD (3.8 g/kg) for 16 weeks, respectively. The free fatty acids-induced lipotoxicity in HepG2 cells were used to evaluate the anti-pyroptotic effects of JLD. The pharmacological effects of JLD on NAFL were investigated by pathological examination, intraperitoneal glucose and insulin tolerance tests, western blotting, and quantitative real-time PCR. RESULTS: In vivo studies showed that JLD ameliorated HFD-induced liver injury, significantly decreased body weight and enhanced insulin sensitivity and improved glucose tolerance. Furthermore, JLD suppressed both the mRNA expression of caspase-1 (1.58 vs. 2.90), IL-1ß (0.93 vs. 3.44) and IL-18 (1.34 vs. 1.60) and protein expression of NLRP3 (2.04 vs. 5.71), pro-caspase-1 (2.68 vs. 4.92) and IL-1ß (1.61 vs. 2.60). In vitro, JLD inhibited the formation of lipid droplets induced by 2 mM FFA (IC50 = 2.727 mM), reduced the protein expression of NLRP3 (0.74 vs. 2.27), caspase-1 (0.57 vs. 2.68), p20 (1.67 vs. 3.33), and IL-1ß (1.44 vs. 2.41), and lowered the ratio of p-IKB-α/IKB-α (0.47 vs. 2.19). CONCLUSION: JLD has a protective effect against NAFLD, which may be related to its anti-pyroptosis, suggesting that JLD has the potential as a novel agent in the treatment of NAFLD.

TRIM4 interacts with TRPM8 and regulates its channel function through K423-mediated ubiquitination.

Transient receptor potential melastatin member 8 (TRPM8), a Ca2+ -permeable nonselective cation channel activated by cold and cooling agents, mediates allodynia. Dysfunction or abnormal expression of TRPM8 has been found in several human cancers. The role of ubiquitination in the regulation of TRPM8 function remains poorly understood. Here, we identified the ubiquitin (Ub)-ligase E3, tripartite motif-containing 4 (TRIM4), as a novel interaction partner of TRPM8 and confirmed that the TRIM4-TRPM8 interaction was mediated through the SPRY domain of TRIM4. Patch-clamp assays showed that TRIM4 negatively regulates TRPM8-mediated currents in HEK293 cells. Moreover, TRIM4 reduced the expression of TRPM8 on the cell surface by promoting the K63-linked ubiquitination of TRPM8. Further analyses revealed that the TRPM8 N-terminal lysine residue at 423 was the major ubiquitination site that mediates its functional regulation by TRIM4. A Ub-activating enzyme E1, Ub-like modifier-activating enzyme 1 (UBA1), was also found to interact with TRPM8, thereby regulating its channel function and ubiquitination. In addition, knockdown of UBA1 impaired the regulation of TRPM8 ubiquitination and function by TRIM4. Thus, this study demonstrates that TRIM4 downregulates TRPM8 via K423-mediated TRPM8 ubiquitination and requires UBA1 to regulate TRPM8.

N-3-oxo-octanoyl-homoserine lactone-mediated priming of resistance to Pseudomonas syringae requires the salicylic acid signaling pathway in Arabidopsis thaliana.

BACKGROUD: Many Gram-negative bacteria use N-acyl-homoserine lactones (AHLs) to communicate each other and to coordinate their collective behaviors. Recently, accumulating evidence shows that host plants are able to sense and respond to bacterial AHLs. Once primed, plants are in an altered state that enables plant cells to more quickly and/or strongly respond to subsequent pathogen infection or abiotic stress. RESULTS: In this study, we report that pretreatment with N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL) confers resistance against the pathogenic bacterium Pseudomonas syringae pv. tomato DC3000 (PstDC3000) in Arabidopsis. Pretreatment with 3OC8-HSL and subsequent pathogen invasion triggered an augmented burst of hydrogen peroxide, salicylic acid accumulation, and fortified expression of the pathogenesis-related genes PR1 and PR5. Upon PstDC3000 challenge, plants treated with 3OC8-HSL showed increased activities of defense-related enzymes including peroxidase, catalase, phenylalanine ammonialyase, and superoxide dismutase. In addition, the 3OC8-HSL-primed resistance to PstDC3000 in wild-type plants was impaired in plants expressing the bacterial NahG gene and in the npr1 mutant. Moreover, the expression levels of isochorismate synthases (ICS1), a critical salicylic acid biosynthesis enzyme, and two regulators of its expression, SARD1 and CBP60g, were potentiated by 3OC8-HSL pretreatment followed by pathogen inoculation. CONCLUSIONS: Our data indicate that 3OC8-HSL primes the Arabidopsis defense response upon hemibiotrophic bacterial infection and that 3OC8-HSL-primed resistance is dependent on the SA signaling pathway. These findings may help establish a novel strategy for the control of plant disease.

Long non-coding RNA HOXA11-AS induces type I collagen synthesis to stimulate keloid formation via sponging miR-124-3p and activation of Smad5 signaling.

Keloid, characterized by exuberant collagen deposition and invasive growth beyond original wound margins, results from abnormal wound healing. A recent microarray analysis identified homeobox (HOX) A11 antisense (HOXA11-AS) as a keloid-specific long non-coding RNA, although its potential role in keloid formation remains elusive. In this study, hematoxylin-eosin, Masson, and immunohistochemical staining of type I collagen (ColI) revealed abnormal arrangement and hyperplasia of fibers in keloid tissues along with increased ColI level. qRT-PCR and Western blot showed that HOXA11-AS and ColI were significantly upregulated, while miR-124-3p was decreased in both keloid tissues and human keloid fibroblasts (HKFs). Knockdown of HOXA11-AS inhibited cell proliferation (by CCK-8 and immunofluorescence staining of Ki67) and cell migration (by wound healing and transwell assays). Mechanistic experiments verified that HOXA11-AS acted as a sponge of micro-RNA (miR)-124-3p and Smad5 was a target of miR-124-3p. miR-124-3p sufficiently reversed the regulatory effects of HOXA11-AS, and Smad5 was involved in miR-124-3p-mediated biological functions. Furthermore, HOXA11-AS induced ColI synthesis via sponging miR-124-3p-mediated Smad5 signaling, thus promoting keloid formation. Overall, our study implied that HOXA11-AS induces ColI synthesis to promoted keloid formation via sponging miR-124-3p-mediated Smad5 signaling, which might offer a novel target for developing the therapy of keloid formation.

Involvement of jasmonic acid, ethylene and salicylic acid signaling pathways behind the systemic resistance induced by Trichoderma longibrachiatum H9 in cucumber.

BACKGROUND: Trichoderma spp. are effective biocontrol agents for many plant pathogens, thus the mechanism of Trichoderma-induced plant resistance is not fully understood. In this study, a novel Trichoderma strain was identified, which could promote plant growth and reduce the disease index of gray mold caused by Botrytis cinerea in cucumber. To assess the impact of Trichoderma inoculation on the plant response, a multi-omics approach was performed in the Trichoderma-inoculated cucumber plants through the analyses of the plant transcriptome, proteome, and phytohormone content. RESULTS: A novel Trichoderma strain was identified by morphological and molecular analysis, here named T. longibrachiatum H9. Inoculation of T. longibrachiatum H9 to cucumber roots promoted plant growth in terms of root length, plant height, and fresh weight. Root colonization of T. longibrachiatum H9 in the outer layer of epidermis significantly inhibited the foliar pathogen B. cinerea infection in cucumber. The plant transcriptome and proteome analyses indicated that a large number of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were identified in cucumber plants 96 h post T. longibrachiatum H9 inoculation. Up-regulated DEGs and DEPs were mainly associated with defense/stress processes, secondary metabolism, and phytohormone synthesis and signaling, including jasmonic acid (JA), ethylene (ET) and salicylic acid (SA), in the T. longibrachiatum H9-inoculated cucumber plants in comparison to untreated plants. Moreover, the JA and SA contents significantly increased in cucumber plants with T. longibrachiatum H9 inoculation. CONCLUSIONS: Application of T. longibrachiatum H9 to the roots of cucumber plants effectively promoted plant growth and significantly reduced the disease index of gray mold caused by B. cinerea. The analyses of the plant transcriptome, proteome and phytohormone content demonstrated that T. longibrachiatum H9 mediated plant systemic resistance to B. cinerea challenge through the activation of signaling pathways associated with the phytohormones JA/ET and SA in cucumber.

Testosterone alleviates mitochondrial ROS accumulation and mitochondria-mediated apoptosis in the gastric mucosa of orchiectomized rats.

The effects of testosterone propionate (TP) on the oxidative stress and mitochondrial function, as well as on mitochondria associated apoptotic signaling, were analyzed in the gastric mucosa in orchiectomized male rats. The present study showed that testosterone deficiency triggered apoptosis by damaging the mitochondrial function (ROS overload generation, membrane potential loss, ATP depletion, etc.), increasing both the release of mitochondrial cytochrome c (Cyt c) and the Bax/Bcl-2 ratio, and activating caspase-9 and caspase-3. Supplements of testosterone propionate to castrated male rats ameliorated mitochondrial function and confirmed the involvement of the mitochondrial pathway in the gastric mucosa. These results suggest that testosterone could maintain the mitochondrial function of the gastric mucosa and mediate mitochondria-associated apoptotic signaling.

Sumoylation E3 Ligase SIZ1 Modulates Plant Immunity Partly through the Immune Receptor Gene SNC1 in Arabidopsis.

The small ubiqutin-like modifier E3 ligase SIZ1 regulates multiple processes in Arabidopsis, including salicylic-acid-dependent immune responses. However, the targets of SIZ1 in plant immunity are not known. Here, we provide evidence that the plant immune receptor nucleotide-binding leucine-rich repeat gene SNC1 partially mediates the regulation of plant immunity by SIZ1. The siz1 loss-of-function mutant has an autoimmune phenotype that is dependent on SNC1 and temperature. Overexpression of SIZ1 partially rescues autoimmune mutant phenotypes induced by activation or overaccumulation of SNC1, and the SNC1 protein amount is attenuated by SIZ1 overexpression. In addition, overexpression of the F-box protein CPR1 that degrades the SNC1 protein inhibits the growth defects and disease resistance of the siz1 mutant. Furthermore, we found that the SNC1 protein is sumoylated in planta. Although it remains to be determined whether SIZ1 primarily modulates the SNC1 protein via sumoylation or affects SNC1 transcript level, our data indicate that SNC1 is a major mediator of defense response modulated by SIZ1 and that SNC1 is a crucial target for fine-tuning plant defense responses.