The U-Box E3 Ubiquitin Ligase PUB35 Negatively Regulates ABA Signaling through AFP1-mediated Degradation of ABI5.

Abscisic acid (ABA) signaling is crucial for plant responses to various abiotic stresses. The Arabidopsis (Arabidopsis thaliana) transcription factor ABA INSENSITIVE 5 (ABI5) is a central regulator of ABA signaling. ABI5 BINDING PROTEIN 1 (AFP1) interacts with ABI5 and facilitates its 26S-proteasome-mediated degradation, although the detailed mechanism has remained unclear. Here, we report that an ABA-responsive U-box E3 ubiquitin ligase, PLANT U-BOX 35 (PUB35), physically interacts with AFP1 and ABI5. PUB35 directly ubiquitinated ABI5 in a bacterially reconstituted ubiquitination system and promoted ABI5 protein degradation in vivo. ABI5 degradation was enhanced by AFP1 in response to ABA treatment. Phosphorylation of the T201 and T206 residues in ABI5 disrupted the ABI5-AFP1 interaction and affected the ABI5-PUB35 interaction and PUB35-mediated degradation of ABI5 in vivo. Genetic analysis of seed germination and seedling growth showed that pub35 mutants were hypersensitive to ABA as well as to salinity and osmotic stresses, whereas PUB35 overexpression lines were hyposensitive. Moreover, abi5 was epistatic to pub35, whereas the pub35-2 afp1-1 double mutant showed a similar ABA response to the two single mutants. Together, our results reveal a PUB35-AFP1 module involved in fine-tuning ABA signaling through ubiquitination and 26S-proteasome-mediated degradation of ABI5 during seed germination and seedling growth.

Ultrasound-guided interscalene block versus intravenous analgesia and sedation for reduction of first anterior shoulder dislocation.

PURPOSE: This study aims to compare the efficacy of ultrasound-guided interscalene block (US-ISB) with that of intravenous analgesia and sedation (IVAS) in reducing first shoulder dislocation. MATERIAL AND METHODS: A prospective study was performed in 66 patients with first anterior shoulder dislocation in emergency department. The patients were divided into a US-ISB (n = 32) group and an IVAS (IVAS n = 34) group. The procedure time (anesthesia, reduction, and hospital times), pain score (before, during, and after reduction), reduction attempts, complications, and patient satisfaction were recorded and compared between the two groups. RESULTS: The anesthesia time (P < 0.01) and reduction time (P < 0.01) were shorter and the hospital time (P < 0.01) was longer in the IVAS group than in the US-ISB group. No significant differences in preoperative (P = 0.18) and postoperative (P = 0.27) pain scores were found between the two groups, but the intraoperative score of the US-ISB group was significantly higher than that of the IVAS group. More reduction attempts (P < 0.01) were recorded in the US-ISB group than that in the IVAS group. Complications (P < 0.01) such as nausea, vomiting, headache, and hypoxia occurred more frequently in the IVAS group than in the US-ISB group. No significant difference in patient satisfaction was observed between two groups (P = 0.96). CONCLUSION: Compared with IVAS group, US-ISB group reduces the time to discharge and achieves lesser complication. The pain score and reduction attempt are lower in the IVAS group than in the US-ISB group.

The E3 Ligase DROUGHT HYPERSENSITIVE Negatively Regulates Cuticular Wax Biosynthesis by Promoting the Degradation of Transcription Factor ROC4 in Rice.

Cuticular wax plays crucial roles in protecting plants from environmental stresses, particularly drought stress. Many enzyme-encoding genes and transcription factors involved in wax biosynthesis have been identified, but the underlying posttranslational regulatory mechanisms are poorly understood. Here, we demonstrate that DROUGHT HYPERSENSITIVE (DHS), encoding a Really Interesting New Gene (RING)-type protein, is a critical regulator of wax biosynthesis in rice (Oryza sativa). The cuticular wax contents were significantly reduced in DHS overexpression plants but increased in dhs mutants compared with the wild type, which resulted in a response opposite that of drought stress. DHS exhibited E3 ubiquitin ligase activity and interacted with the homeodomain-leucine zipper IV protein ROC4. Analysis of ROC4 overexpression plants and roc4 mutants indicated that ROC4 positively regulates cuticular wax biosynthesis and the drought stress response. ROC4 is ubiquitinated in vivo and subjected to ubiquitin/26S proteasome-mediated degradation. ROC4 degradation was promoted by DHS but delayed in dhs mutants. ROC4 acts downstream of DHS, and Os-BDG is a direct downstream target of the DHS-ROC4 cascade. These results suggest a mechanism whereby DHS negatively regulates wax biosynthesis by promoting the degradation of ROC4, and they suggest that DHS and ROC4 are valuable targets for the engineering of drought-tolerant rice cultivars.

Proteomic analysis of affinity-purified 26S proteasomes identifies a suite of assembly chaperones in Arabidopsis.

The 26S proteasome is an essential protease that selectively eliminates dysfunctional and short-lived regulatory proteins in eukaryotes. To define the composition of this proteolytic machine in plants, we tagged either the core protease (CP) or the regulatory particle (RP) sub-complexes in Arabidopsis to enable rapid affinity purification followed by mass spectrometric analysis. Studies on proteasomes enriched from whole seedlings, with or without ATP needed to maintain the holo-proteasome complex, identified all known proteasome subunits but failed to detect isoform preferences, suggesting that Arabidopsis does not construct distinct proteasome sub-types. We also detected a suite of proteasome-interacting proteins, including likely orthologs of the yeast and mammalian chaperones Pba1, Pba2, Pba3, and Pba4 that assist in CP assembly; Ump1 that helps connect CP half-barrels; Nas2, Nas6, and Hsm3 that assist in RP assembly; and Ecm29 that promotes CP-RP association. Proteasomes from seedlings exposed to the proteasome inhibitor MG132 accumulated assembly intermediates, reflecting partially built proteasome sub-complexes associated with assembly chaperones, and the CP capped with the PA200/Blm10 regulator. Genetic analyses of Arabidopsis UMP1 revealed that, unlike in yeast, this chaperone is essential, with mutants lacking the major UMP1a and UMP1b isoforms displaying a strong gametophytic defect. Single ump1 mutants were hypersensitive to conditions that induce proteotoxic, salt and osmotic stress, and also accumulated several proteasome assembly intermediates, consistent with its importance for CP construction. Insights into the chaperones reported here should enable study of the assembly events that generate the 26S holo-proteasome in Arabidopsis from the collection of 64 or more subunits.

Circulating miR-23b as a Novel Biomarker for Early Risk Stratification After ST-Elevation Myocardial Infarction.

BACKGROUND miR-23b overexpression can promote cardiomyocyte apoptosis and reduce cell growth under hypoxic conditions, suggesting that miR-23b acts as a biomarker for ST-elevation myocardial infarction (STEMI). The aim of this study was to investigate the effect of miR-23b on STEMI patients. MATERIAL AND METHODS We enrolled 80 eligible patients with STEMI and 60 control subjects. Blood samples were obtained at 6 h, 12 h, 24 h, 48 h, 3 days, and 7 days after the onset of symptoms. Another blood sample was collected before and after percutaneous coronary intervention (PCI). The samples were used for real-time quantitative PCR analysis. A Siemens Immulite2000 detector (Germany) was used for cTnI detection, and the serum CK-MB content was detected by electrochemical luminescence method. RESULTS The expression level of miR-23b was increased in patients with STEMI (P<0.05). No significance difference was observed among risk factors, although the clinical data was comparable (P>0.05). The level of miR-23b in STEMI patients after PCI was lower (P<0.05). The ROC curve of plasma miR-23b showed a separation, with an AUC of 0.809 (95%CI, 0.737-0.936, P<0.05), compared to CK-MB with an AUC of 0.753 (95%CI, 0.707-0.896) and cTnI with an AUC of 0.783 (95%CI, 0.723-0.917). CONCLUSIONS The present study reveals that miR-23b is a useful biomarker of STEMI, providing a novel insight for the diagnosis for STEMI.

The RING finger E3 ligase STRF1 is involved in membrane trafficking and modulates salt-stress response in Arabidopsis thaliana.

Salt stress is a detrimental factor for plant growth and development. The response to salt stress has been shown to involve components in the intracellular trafficking system, as well as components of the ubiquitin-proteasome system (UPS). In this article, we have identified in Arabidopsis thaliana a little reported ubiquitin ligase involved in salt-stress response, which we named STRF1 (Salt Tolerance RING Finger 1). STRF1 is a member of RING-H2 finger proteins and we demonstrate that it has ubiquitin ligase activity in vitro. We also show that STRF1 localizes mainly at the plasma membrane and at the intracellular endosomes. strf1-1 loss-of-function mutant seedlings exhibit accelerated endocytosis in roots, and have altered expression of several genes involved in the membrane trafficking system. Moreover, protein trafficking inhibitor, brefeldin A (BFA), treatment has increased BFA bodies in strf1-1 mutant. This mutant also showed increased tolerance to salt, ionic and osmotic stresses, reduced accumulation of reactive oxygen species during salt stress, and increased expression of AtRbohD, which encodes a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase involved in H2 O2 production. We conclude that STRF1 is a membrane trafficking-related ubiquitin ligase, which helps the plant to respond to salt stress by monitoring intracellular membrane trafficking and reactive oxygen species (ROS) production.

Corticosteroids Significantly Increase Serum Cystatin C Concentration without Affecting Renal Function in Symptomatic Heart Failure.

BACKGROUND: Human cystatin C is a single non-glycosylated polypeptide chain consisting of 120 amino acid residues. Its concentration in the circulation is mainly determined by glomerular filtration rate. However, non-renal factors, i.e., drugs, may dramatically affect its levels in the circulation. The aim of this study was to evaluate the effect of corticosteroid treatment on serum cystatin C concentration in patients with symptomatic heart failure. METHODS: Fifty-six symptomatic heart failure patients were treated with prednisone. Concentrations of serum cystatin C and serum creatinine were recorded at baseline, and after about 2 weeks of treatment. Twenty-four hour urinary creatinine was also measured to directly calculate glomerular filtration rate. RESULTS: Prednisone treatment significantly increased serum cystatin C concentration from 1.24 +/- 0.40 mg/L at baseline to 1.61 +/- 0.80 mg/L at the end of study (p < 0.05). However, the elevation in serum cystatin C concentration was not associated with renal function impairment. Prednisone not only significantly decreased serum creatinine concentrations from 89.66 +/- 28.63 pmol/L at baseline to 76.55 +/- 20.80 micromol/L after prednisone treatment (p < 0.05), but also significantly increased fractional excretion of sodium and urine flow rate. The data also showed there was a slight and but nonstatistically significant increase in glomerular filtration rate in such patients after prednisone treatment. CONCLUSIONS: Important non-renal factors, such as corticosteroids, can influence cystatin C concentration. Thus, it needs to be considered when interpreting cystatin C values in patients with heart failure receiving corticosteroid therapy.

Prednisone lowers serum uric acid levels in patients with decompensated heart failure by increasing renal uric acid clearance.

Clinical studies have shown that large doses of prednisone could lower serum uric acid (SUA) in patients with decompensated heart failure (HF); however, the optimal dose of prednisone and underlying mechanisms are unknown. Thirty-eight patients with decompensated HF were randomized to receive standard HF care alone (n = 10) or with low-dose (15 mg/day, n = 8), medium-dose (30 mg/day, n = 10), or high-dose prednisone (60 mg/day, n = 10), for 10 days. At the end of the study, only high-dose prednisone significantly reduced SUA, whereas low- and medium-dose prednisone and standard HF care had no effect on SUA. The reduction in SUA in high-dose prednisone groups was associated with a significant increase in renal uric acid clearance. In conclusion, prednisone can reduce SUA levels by increasing renal uric acid clearance in patients with decompensated HF.

Arabidopsis ubiquitin conjugase UBC32 is an ERAD component that functions in brassinosteroid-mediated salt stress tolerance.

Plants modify their growth and development to protect themselves from detrimental conditions by triggering a variety of signaling pathways, including the activation of the ubiquitin-mediated protein degradation pathway. Endoplasmic reticulum (ER)-associated protein degradation (ERAD) is an important aspect of the ubiquitin-proteasome system, but only a few of the active ERAD components have been reported in plants. Here, we report that the Arabidopsis thaliana ubiquitin-conjugating enzyme, UBC32, a stress-induced functional ubiquitin conjugation enzyme (E2) localized to the ER membrane, connects the ERAD process and brassinosteroid (BR)-mediated growth promotion and salt stress tolerance. In vivo data showed that UBC32 was a functional ERAD component that affected the stability of a known ERAD substrate, the barley (Hordeum vulgare) powdery mildew O (MLO) mutant MLO-12. UBC32 mutation caused the accumulation of bri1-5 and bri1-9, the mutant forms of the BR receptor, BRI1, and these mutant forms subsequently activated BR signal transduction. Further genetic and physiological data supported the contention that UBC32 plays a role in the BR-mediated salt stress response and that BR signaling is necessary for the plant to tolerate salt. Our data indicates a possible mechanism by which an ERAD component regulates the growth and stress response of plants.

Effect of Corticosteroid on Renal Water and Sodium Excretion in Symptomatic Heart Failure: Prednisone for Renal Function Improvement Evaluation Study.

BACKGROUND: Recent evidence indicates that prednisone can potentiate renal responsiveness to diuretics in heart failure (HF). However, the optimal dose of prednisone is not known. METHOD: Thirty-eight patients with symptomatic HF were randomized to receive standard HF care alone (n = 10) or with low-dose (15 mg/d, n = 8), medium-dose (30 mg/d, n = 10), or high-dose prednisone (60 mg/d, n = 10), for 10 days. During this time, we recorded the 24-hour urinary output and the 24-hour urinary sodium excretion, at baseline, on day 5 and day 10. We also monitored the change in the concentration of serum creatinine, angiotensin II, aldosterone, high-sensitive C-reactive protein, tumor necrosis factor-α, interleukin 1ß, and interleukin 6. RESULTS: Low-dose prednisone significantly enhanced urine output. However, the effects of medium- and high-dose prednisone on urine output were less obvious. As for renal sodium excretion, high-dose prednisone induced a more potent natriuresis than low-dose prednisone. Despite the potent diuresis and natriuresis induced by prednisone, serum creatinine, angiotensin II, and aldosterone levels were not elevated. These favorable effects were not associated with an inflammatory suppression by glucocorticoids. CONCLUSIONS: Only low-dose prednisone significantly enhanced urine output. However, high-dose prednisone induced a more potent renal sodium excretion than low-dose prednisone.

A plant-specific in vitro ubiquitination analysis system.

Protein ubiquitination requires the concerted action of three enzymes: ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2) and ubiquitin ligase (E3). These ubiquitination enzymes belong to an abundant protein family that is encoded in all eukaryotic genomes. Describing their biochemical characteristics is an important part of their functional analysis. It has been recognized that various E2/E3 specificities exist, and that detection of E3 ubiquitination activity in vitro may depend on the recruitment of E2s. Here, we describe the development of an in vitro ubiquitination system based on proteins encoded by genes from Arabidopsis. It includes most varieties of Arabidopsis E2 proteins, which are tested with several RING-finger type E3 ligases. This system permits determination of E3 activity in combination with most of the E2 sub-groups that have been identified in the Arabidopsis genome. At the same time, E2/E3 specificities have also been explored. The components used in this system are all from plants, particularly Arabidopsis, making it very suitable for ubiquitination assays of plant proteins. Some E2 proteins that are not easily expressed in Escherichia coli were transiently expressed and purified from plants before use in ubiquitination assays. This system is also adaptable to proteins of species other than plants. In this system, we also analyzed two mutated forms of ubiquitin, K48R and K63R, to detect various types of ubiquitin conjugation.

BSCTV C2 attenuates the degradation of SAMDC1 to suppress DNA methylation-mediated gene silencing in Arabidopsis.

Plant viruses are excellent tools for studying microbial-plant interactions as well as the complexities of host activities. Our study focuses on the role of C2 encoded by Beet severe curly top virus (BSCTV) in the virus-plant interaction. Using BSCTV C2 as bait in a yeast two-hybrid screen, a C2-interacting protein, S-adenosyl-methionine decarboxylase 1 (SAMDC1), was identified from an Arabidopsis thaliana cDNA library. The interaction was confirmed by an in vitro pull-down assay and a firefly luciferase complemention imaging assay in planta. Biochemical analysis further showed that the degradation of the SAMDC1 protein was inhibited by MG132, a 26S proteasome inhibitor, and that C2 could attenuate the degradation of the SAMDC1 protein. Genetic analysis showed that loss of function of SAMDC1 resulted in reduced susceptibility to BSCTV infection and reduced viral DNA accumulation, similar to the effect of BSCTV C2 deficiency. Bisulfite sequencing analysis further showed that C2 deficiency caused enhanced DNA methylation of the viral genome in infected plants. We also showed that C2 can suppress de novo methylation in the FWA transgenic assay in the C2 transgene background. Overexpression of SAMDC1 can mimic the suppressive activity of C2 against green fluorescent protein-directed silencing. These results suggest that C2 interferes with the host defense mechanism of DNA methylation-mediated gene silencing by attenuating the 26S proteasome-mediated degradation of SAMDC1.

Influence of Fracturing on a Coal Structure during Coalbed Methane Stimulation.

The impact of fracturing on coal seams includes not only mechanical alterations but also physical and chemical alterations. The coupling of these alterations plays an important role in the recovery of coalbed methane (CBM). 13C nuclear magnetic resonance (13C NMR), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and molecular models were conducted on coals with different degrees of fracturing to study the alterations in the coal structure during CBM stimulation. The 13C NMR results show that some aliphatic chains and oxygen-containing functional groups were shed, and some aliphatic rings were broken due to the effects of fracturing, which cause an increase in the relative content of aromatic carbon. The HRTEM and XRD results indicate that fracturing will result in a decrease in the interlayer spacing d002, an increase in the stacking height Lc, and a slight increase in the layer size La. Moreover, the orientation distribution in fractured coal was more intensive. The construction of molecular models also verified the variation of surface functional groups and interlayer spacing. Based on these analyses and molecular models, the alteration mechanism of functional groups and aromatic structures under fracturing was demonstrated. This study clarifies the alteration of the coal structure by fracturing and has important implications for the recovery of CBM.

Quantitative analysis of abdominal aortic blood flow by 99mTc-DTPA renal scintigraphy in patients with heart failure.

OBJECTIVE: This study aimed to explore the characteristics of abdominal aortic blood flow in patients with heart failure (HF) using 99mTc-diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy. We investigated the ability of renal scintigraphy to measure the cardiopulmonary transit time and assessed whether the time-to-peak of the abdominal aorta (TTPa) can distinguish between individuals with and without HF. METHODS: We conducted a retrospective study that included 304 and 37 patients with and without HF (controls), respectively. All participants underwent 99mTc-DTPA renal scintigraphy. The time to peak from the abdominal aorta's first-pass time-activity curve was noted and compared between the groups. The diagnostic significance of TTPa for HF was ascertained through receiver operating characteristic (ROC) analysis and logistic regression. Factors influencing the TTPa were assessed using ordered logistic regression. RESULTS: The HF group displayed a significantly prolonged TTPa than controls (18.5 [14, 27] s vs. 11 [11, 13] s). Among the HF categories, HF with reduced ejection fraction (HFrEF) exhibited the longest TTPa compared with HF with mildly reduced (HFmrEF) and preserved EF (HFpEF) (25 [17, 36.5] s vs. 17 [15, 23] s vs. 15 [11, 17] s) (P < 0.001). The ROC analysis had an area under the curve of 0.831, which underscored TTPa's independent diagnostic relevance for HF. The diagnostic precision was enhanced as left ventricular ejection fraction (LVEF) declined and HF worsened. Independent factors for TTPa included the left atrium diameter, LVEF, right atrium diameter, velocity of tricuspid regurgitation, and moderate to severe aortic regurgitation. CONCLUSIONS: Based on 99mTc-DTPA renal scintigraphy, TTPa may be used as a straightforward and non-invasive tool that can effectively distinguish patients with and without HF.

The U-Box/ARM E3 ligase PUB13 regulates cell death, defense, and flowering time in Arabidopsis.

The components in plant signal transduction pathways are intertwined and affect each other to coordinate plant growth, development, and defenses to stresses. The role of ubiquitination in connecting these pathways, particularly plant innate immunity and flowering, is largely unknown. Here, we report the dual roles for the Arabidopsis (Arabidopsis thaliana) Plant U-box protein13 (PUB13) in defense and flowering time control. In vitro ubiquitination assays indicated that PUB13 is an active E3 ubiquitin ligase and that the intact U-box domain is required for the E3 ligase activity. Disruption of the PUB13 gene by T-DNA insertion results in spontaneous cell death, the accumulation of hydrogen peroxide and salicylic acid (SA), and elevated resistance to biotrophic pathogens but increased susceptibility to necrotrophic pathogens. The cell death, hydrogen peroxide accumulation, and resistance to necrotrophic pathogens in pub13 are enhanced when plants are pretreated with high humidity. Importantly, pub13 also shows early flowering under middle- and long-day conditions, in which the expression of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 and FLOWERING LOCUS T is induced while FLOWERING LOCUS C expression is suppressed. Finally, we found that two components involved in the SA-mediated signaling pathway, SID2 and PAD4, are required for the defense and flowering-time phenotypes caused by the loss of function of PUB13. Taken together, our data demonstrate that PUB13 acts as an important node connecting SA-dependent defense signaling and flowering time regulation in Arabidopsis.

Arabidopsis RING peroxins are E3 ubiquitin ligases that interact with two homologous ubiquitin receptor proteins(F).

Peroxisomes are essential eukaryotic organelles that mediate various metabolic processes. Peroxisome import depends on a group of peroxisome biogenesis factors called peroxins, many of which are evolutionarily conserved. PEX2, PEX10, and PEX12 are three RING-finger-domain-containing integral membrane peroxins crucial for protein import. In yeast (Saccharomyces cerevisae), RING peroxins act as E3 ligases, facilitating the recycling of the peroxisome import receptor protein PEX5 through ubiquitination. In plants, RING peroxins are essential to plant vitality. To elucidate the mode of action of the plant RING peroxins, we employed in vitro assays to show that the Arabidopsis RING peroxins also have E3 ligase activities. We also identified a PEX2-interacting protein, DSK2b, which is a member of the ubiquitin receptor family known to function as shuttle factors ferrying polyubiquitinated substrates to the proteasome for degradation. DSK2b and its tandem duplicate DSK2a are localized in the cytosol and the nucleus, and both interact with the RING domain of PEX2 and PEX12. DSK2 artificial microRNA lines did not display obvious defects in plant growth or peroxisomal processes, indicating functional redundancies among Arabidopsis ubiquitin receptor proteins. Our results suggest that Arabidopsis RING peroxins can function as E3 ligases and act together with the ubiquitin receptor protein DSK2 in the peroxisomal membrane-associated protein degradation system.

JMJ28 guides sequence-specific targeting of ATX1/2-containing COMPASS-like complex in Arabidopsis.

Despite extensive investigations in mammals and yeasts, the importance and specificity of COMPASS-like complex, which catalyzes histone 3 lysine 4 methylation (H3K4me), are not fully understood in plants. Here, we report that JMJ28, a Jumonji C domain-containing protein in Arabidopsis, recognizes specific DNA motifs through a plant-specific WRC domain and acts as an interacting factor to guide the chromatin targeting of ATX1/2-containing COMPASS-like complex. JMJ28 associates with COMPASS-like complex in vivo via direct interaction with RBL. The DNA-binding activity of JMJ28 is essential for both the targeting specificity of ATX1/2-COMPASS and the deposition of H3K4me at specific loci but exhibit functional redundancy with alternative COMPASS-like complexes at other loci. Finally, we demonstrate that JMJ28 is a negative regulator of plant immunity. In summary, our findings reveal a plant-specific recruitment mechanism of COMPASS-like complex. These findings help to gain deeper insights into the regulatory mechanism of COMPASS-like complex in plants.

The Arabidopsis RING finger E3 ligase RHA2b acts additively with RHA2a in regulating abscisic acid signaling and drought response.

We have previously shown that the Arabidopsis (Arabidopsis thaliana) RING-H2 E3 ligase RHA2a positively regulates abscisic acid (ABA) signaling during seed germination and postgerminative growth. Here, we report that RHA2b, the closest homolog of RHA2a, is also an active E3 ligase and plays an important role in ABA signaling. We show that RHA2b expression is induced by ABA and that overexpression of RHA2b leads to ABA-associated phenotypes such as ABA hypersensitivity in seed germination and seedling growth, enhanced stomatal closure, reduced water loss, and, therefore, increased drought tolerance. On the contrary, the rha2b-1 mutant shows ABA-insensitive phenotypes and reduced drought tolerance. We provide evidence showing that a rha2a rha2b-1 double mutant generally enhances ABA insensitivity of rha2b-1 in seed germination, seedling growth, and stomatal closure, suggesting that RHA2b and RHA2a act redundantly in regulating ABA responses. Genetic analyses support that, like RHA2a, the RHA2b action in ABA signaling is downstream of a protein phosphatase 2C, ABA-INSENSITIVE2 (ABI2), and in parallel with that of the ABI transcription factors ABI3/4/5. We speculate that RHA2b and RHA2a may have redundant yet distinguishable functions in the regulation of ABA responses.

The SINA E3 ligase OsDIS1 negatively regulates drought response in rice.

Ubiquitin-regulated protein degradation is a critical regulatory mechanism that controls a wide range of biological processes in plants. Here, we report that OsDIS1 (for Oryza sativa drought-induced SINA protein 1), a C3HC4 RING finger E3 ligase, is involved in drought-stress signal transduction in rice (O. sativa). The expression of OsDIS1 was up-regulated by drought treatment. In vitro ubiquitination assays showed that OsDIS1 possessed E3 ubiquitin ligase activity and that the conserved region of the RING finger was required for the activity. Transient expression assays in Nicotiana benthamiana leaves and rice protoplasts indicated that OsDIS1 was localized predominantly in the nucleus. Overexpression of OsDIS1 reduced drought tolerance in transgenic rice plants, while RNA interference silencing of OsDIS1 enhanced drought tolerance. Microarray analysis revealed that a large number of drought-responsive genes were induced or suppressed in the OsDIS1 overexpression plants under normal and drought conditions. Yeast two-hybrid screening showed that OsDIS1 interacted with OsNek6 (for O. sativa NIMA-related kinase 6), a tubulin complex-related serine/threonine protein kinase. Coexpression assays in N. benthamiana leaves indicated that OsNek6 was degraded by OsDIS1 via the 26S proteasome-dependent pathway and that this degradation was abolished by the OsDIS1(H71Y) mutation, which is essential for its E3 ligase activity. Together, these results demonstrate that OsDIS1 plays a negative role in drought stress tolerance through transcriptional regulation of diverse stress-related genes and possibly through posttranslational regulation of OsNek6 in rice.

Intranasal immunization with recombinant Vaccinia virus encoding trimeric SARS-CoV-2 spike receptor-binding domain induces neutralizing antibody.

Respiratory transmission of SARS-CoV-2 is considered to be the major dissemination route for COVID-19, therefore, mucosal immune responses have great importance in preventing SARS-CoV-2 from infection. In this study, we constructed a recombinant Vaccinia virus (VV) harboring trimeric receptor-binding domain (RBD) of SARS-CoV-2 spike protein (VV-tRBD), and evaluated the immune responses towards RBD following intranasal immunization against mice and rabbits. In BALB/c mice, intranasal immunization with VV-tRBD elicited robust humoral and cellular immune responses, with high-level of both neutralizing IgG and IgA in sera against SARS-CoV-2 psudoviruses, and a number of RBD-specific IFN-γ-secreting lymphocytes. Sera from immunized rabbits also exhibited neutralization effects. Notably, RBD-specific secretory IgA (sIgA) in both nasal washes and bronchoalveolar lavage fluids (BALs) were detectable and showed substantial neutralization activities. Collectively, a recombinant VV expressing trimeric RBD confers robust systemic immune response and mucosal neutralizing antibodies, thus warranting further exploration as a mucosal vaccine.