Degranulation of RBL-2H3 rat basophilic leukemia cells is synergistically inhibited by combined treatment with nobiletin and lactoferrin

The aim of this study was to elucidate the anti-allergic effects of polymethoxyflavonoids in combination with milk proteins and the mechanism of inhibition. Three polymethoxyflavonoids and two milk proteins were exposed to the rat basophilic leukemia cell line RBL-2H3. β-hexosaminidase was used as an indicator of degranulation inhibition. The mechanism of inhibition was examined by measuring intracellular Ca2+ levels and western blot method. In the degranulation inhibition test with polymethoxyflavonoids and milk proteins alone, nobiletin was the strongest inhibitor in the polymethoxyflavonoid group and lactoferrin in the milk protein group. Next, co-stimulation with nobiletin and lactoferrin showed stronger synergistic degranulation inhibition than treatment with nobiletin or lactoferrin alone. Western blot analysis showed that co-stimulation with nobiletin and lactoferrin significantly downregulated the induction of phospholipase Cγ 1 phosphorylation. The degranulation response in RBL-2H3 cells was synergistically suppressed by co-stimulation of nobiletin and lactoferrin acting on both Ca2+-dependent and Ca2+-independent pathways.

Fortify the defense frontline: MAPKs phosphorylate receptor-like cytoplasmic kinase to maintain plant resistance in soybean

Mitogen-activated protein kinase (MAPK) activation is one of the significant immune events that respond to pathogens in plants. A MAPK cascade often contains a MAPK kinase kinase (MAPKKK), a MAPK kinase (MAPKK/MKK), and a MAPK. The well-characterized MAPK cascade, to date, is the MAPKKK3/4/5-MKK4/5-MPK3/6 module. Soybean cyst nematodes (SCN) is one of the most devastating soybean pathogens. However, the early immune components contributing to soybean resistance to SCN and the role of the MAPK cascade in the soybean-SCN interaction remain unclear. A recent study published in Plant Cell discovered that GmMPK3/6 phosphorylates a receptor-like cytoplasmic kinase (RLCK), CDG1-LIKE1 (GmCDL1), and maintains the stability of GmCDL1 in soybean. Remarkably, GmCDL1 enhances GmMPK3/6 activation and resistance to SCN by phosphorylating GmMAPKKK5 and activating the GmMAPKKK5-GmMKK4-GmMPK3/6 cascade. In addition, two L-type lectin receptor kinases (LecRKs), GmLecRK02g and GmLecRK08g, are involved in the GmCDL1 function after the perception of SCN. taken together, this study not only discovers a complete early immune pathway that responds to SCN infection in soybean, but also reveals a molecular mechanism by which plants maintain the activation of the MAPK cascade and resistance.

Effects of plant growth-promoting rhizobacteria on growth indicators and physiological characteristics of Peucedanum praeruptorum Dunn leaves

As a kind of medicinal plant, Peucedanum praeruptorum Dunn has been over-harvested in the wild population, which leads to its artificial cultivation. The present study aims to analyze the effects of different plant growth-promoting rhizobacteria (PGPR) on the growth and physiological characteristics of P. Praeruptorum leaves. Compared with the CK, the content of malondialdehyde (MDA) was drastically reduced in the leaves of P. Praeruptorum in different treatment groups (P < 0.05), and with S6 showing the most significant reduction in MDA content (content was only about 1/3 that of the CK). The indicators of leaf area, length and width were found to be the highest in group S9, reaching a level that is 3.75, 3.08 and 1.48 times higher than those in group CK, respectively. Group S8 has the largest plant height, which is 1.22 times higher than that in group CK. S2 has the largest stem diameter, which is 1.69 times higher than that in group CK. Group S1 has the largest petiole length, which is 1.74 times higher than that in group CK. Group S6 has the largest chlorophyll content, which is 1.63 times higher than that in group CK. Group S2 has the highest content of soluble sugar and soluble protein, which are 2.02 times and 3.82 times higher than those in group CK. Group S9 exhibits the strongest CAT activity, which is 3.71 times higher than that in group CK. S5 exhibits the strongest SOD activity, which is 2.32 times higher than group CK. Group S1 exhibits the strongest POD activity, which is 5.94 times higher than that in group CK. In conclusion, the inoculation with PGPR is effective in improving the growth of P. Praeruptorum leaves and their physiological indicators, which provides guidance on the application of PGPR to achieve the high quality and yield of P. Praeruptorum.

Modified L-shaped incision technique for supracardiac total anomalous pulmonary venous connection as an alternative to sutureless technique

BACKGROUND

The modified L-shaped incision technique (MLIT) was successfully applied to the repair of supracardiac total anomalous pulmonary venous connection (TAPVC) with promising mid-term outcomes. It is, however, unclear whether or not MLIT could be an alternative to sutureless technique (ST).

METHODS

All patients ( n =141) who underwent MLIT or ST repair for supracardiac TAPVC between June 2009 and June 2022 were included and a propensity score-matched analysis was performed to reduce the heterogeneity.

RESULTS

MLIT was performed in 80.9% (114/141), whereas ST was performed in 19.1% (27/141). Patients who underwent MLIT repair had a lower incidence of pulmonary veinous obstruction (PVO)-related reintervention (1.8 vs. 18.5%, P =0.002), and late mortality (2.6 vs. 18.2%, P =0.006). Overall survival at 10 years was 92.5% (87.7-97.7%) for MLIT and 66.8% (44.4-100%) for ST ( P =0.012). Freedom from postoperative PVO at 10 years was 89.1% (83.2-95.5%) for MLIT and 79.9% (65.6-97.4%) for ST ( P =0.12). Cox proportional hazards regression identified prolonged mechanical ventilation duration, postoperative PVO, respiratory dysfunction, and low cardiac output syndrome were associated with postoperative death and PVO-related reintervention.

CONCLUSIONS

The MLIT strategy is a safe, technologically feasible, and effective approach for supracardiac TAPVC, which is associated with more favorable and promising freedom from death and PVO-related reintervention.

Population Genetic Analysis of Paris polyphylla var. yunnanensis Based on cpDNA Fragments

Paris polyphylla var. yunnanensis is a well-known medicinal plant that is mainly distributed in Southwest China; however, its genetic diversity and biodiversity processes are poorly understood. In this study, the sequences of cpDNA trnL-trnF fragments of 15 wild populations and 17 cultivated populations of P. polyphylla var. yunnanensis were amplified, sequenced, and aligned to study the population genetics of this species. Genetic diversity was analyzed based on nucleotide diversity, haplotype diversity, Watterson diversity, population-level diversity, and species-level genetic diversity. Genetic structure and genetic differentiation were explored using haplotype distribution maps and genetic distance matrices. A total of 15 haplotypes were identified in the 32 populations of P. polyphylla var. yunnanensis. Five unique haplotypes were identified from the fourteen haplotypes of the cultivated populations, while only one unique haplotype was identified from the ten haplotypes of the wild populations. The haplotype richness and genetic diversity of the cultivated populations were higher than those of the wild populations (HT = 0.900 vs. 0.861). In addition, there were no statistically significant correlations between geographic distance and genetic distance in the cultivated populations (r = 0.16, p > 0.05), whereas there was a significant correlation between geographical distance and genetic structure in the wild populations (r = 0.32, p > 0.05), indicating that there was a geographical and genetic connection between the wild populations. There was only 2.5% genetic variation between the wild populations and cultivated populations, indicating no obvious genetic differentiation between the wild and cultivated populations. Overall, the genetic background of the cultivated populations was complex, and it was hypothesized that the unique haplotypes and higher diversity of the cultivated populations were caused by the mixed provenance of the cultivated populations.

Congenitally corrected transposition with left ventricular outflow obstruction and cardiac malposition: One-and-a-half ventricular repair vs. Fontan pathway?

Objectives

This study was to assess the mid-term results of the one-and-a-half ventricular repair (hemi-Mustard and bidirectional Glenn procedures combined with the Rastelli procedure) and Fontan pathway for correcting congenitally corrected transposition of great artery (ccTGA) patients with left ventricular outflow tract obstruction (LVOTO) and cardiac malposition.

Methods

In this retrospective study, 74 consecutive ccTGA with LVOTO and cardiac malposition underwent the one-and-a-half ventricular repair (group A; 33 cases) and Fontan operation (group B; 41 cases) between October 2011 and March 2018. The Median follow-up time was 49 (20–84) and 42 (7–85) months in groups A and B, respectively. To estimate excise tolerance the 6-min walk test (MWT) was performed.

Results

No in-hospital death. Compared with group A, group B have significantly less CPB, mechanical ventilation time, and intensive care unit stay, but prolonged pleural effusions developed more frequently in Group B. The survival probability was 90.2% (95% CI, 80.2–100%) and 97.2% (95% CI, 92–100%) at 7 years (p = 0.300) in group A and B. The probability of freedom from re-intervention were 80.6% (95% CI, 66.5–97.6%) and 97.2% (95% CI, 92–100%) at 7 years (p = 0.110). Longitudinal repeated measured echo data at every follow-up time shows that group A has more systemic ventricular EF% (p < 0.001) and less moderate systemic ventricular valve regurgitation (p < 0.001) compared with group B. Estimated by 6 MWT, group A has better outcomes for 6-min walk distance.

Conclusions

For correction of ccTGA with LVOTO and cardiac malposition, the one-and-a-half ventricular repair had superior midterm heart function and excise tolerance.

First report of Botryosphaeria dothidea as the causal agent of a new fruit rot disease of pepper in China

Pepper is an important and widely cultivated economic vegetable in the world (Yin et al., 2021). In June 2021, approximately 25% to 33.3% of the pepper plants had rot disease symptoms in Zhuanghang Comprehensive Experimental Base (30.894829 °N, 121.391374 °E), Fengxian district, Shanghai city, China. Water-soaked spots appeared on fruits that increased in size and leading to smelly fruit decay. To isolate the pathogen, three pepper samples with severe symptoms were collected. The samples were surface disinfected with 70% ethanol for 30 sec, 10% chlorine bleach for 10 min, rinsing with sterile water for three times and the rot tissues were cut and dried on sterile filter paper. The dried paper was later placed on potato dextrose agar (PDA) medium and incubated at 28°C (Tang et al., 2021). After 2-3 days, four types of colonies with different colony appearances were observed, in which only one can induce fruit rot phenotype (data not shown). Four isolates were cultured for molecular identification in each type. ITS1/ITS4, T1/βt-2b and EF1-526F/EF1-1567R primers were used to amplify the internal transcribed spacer region (ITS), the beta-tubulin (TUB2) and the translation elongation factor I alpha (EF1-α) genes, respectively (Chen et al., 2018) and corresponding sequences from the isolates were analyzed with BLAST. Sequences of the isolate which can induce pepper decay were submitted to GenBank under the accession numbers of OM663701 (ITS), OM720127 (TUB2) and OM720128 (EF1-α). The results showed that the pathogen had 99% sequence homology to most strains of Botryosphaeria dothidea (B. dothidea) and displayed the highest sequence similarity to strain LBSX-1 (ITS: KF55123), strain JGT01 (TUB2: MW202404) and isolate CZA (EF1-α: MN025271). Based on molecular characterization, the isolate was identified as B. dothidea isolate SH01. A phylogenetic tree was constructed using Maximum Parsimony (MP) methods by MEGA7, and showed that SH01 was closely related to isolate CMW9075. To confirm the pathogenicity, five healthy pepper fruits were surface sterilized, 500μl of conidial suspension (1×103 conidia/ml) were injected into pepper (sterilized distilled water as control). Six days post inoculation (dpi), fruit rot symptoms appeared and the pepper decayed at 12 dpi. Four days post inoculation with mycelium plugs (from a 4-day-old culture on PDA, PDA plugs as control), hyphae were observed in the inoculation site and B. dothidea was re-isolated from the symptomatic areas, thus fulfilling Koch's postulates (Back et al., 2021, Chen et al., 2020). The pepper rotted severely at 7 dpi. The colonies of SH01 were pale to white and gradually turned into gray in 4-6 days. Conidia of the pathogen were unicellular, aseptate, hyaline and fusiform to fusoid, with dimensions of 19.7-23.5 μm × 3.8-5.2 μm (average = 21.9 μm × 4.8 μm, n = 50). Hyphae were transparent, branched and composed of multiple cells. The characteristic was consistent with the descriptions of B. dothidea (Vasic et al., 2013). B. dothidea belongs to Botryosphaeriaceae, causing widespread diseases in many plant species, commonly associated with cankers and dieback of woody plants and economic crops, such as plumcot trees (Back et al., 2021), eucalyptus (Yu et al., 2009) and soybeans (Chen et al., 2020) in China and Korea. Our findings reported for the first time that B. dothidea (SH01) can induce the pepper rot disease and future work on its pathogenesis may provide strategies for disease control against this fungus.

The complete chloroplast genome sequence of the medicinal plant Crotalaria albida

Crotalaria albida (C. albida) is a traditional Chinese medicinal plant that belongs to Fabaceae family. In this study, the complete chloroplast genome sequence of C. albida was sequenced. The genome is 152,743 bp in length and includes two inverted repeat regions of 25,535 bp. It was predicted to contain 127 genes in the chloroplast genome, among which 82 were protein-coding genes, 37 were tRNA genes, and 8 were rRNA genes. The maximum likelihood phylogenetic analysis based on 24 complete chloroplast genome sequences showed that C. albida was closely related to Ormosia semicastrata, Ormosia emarginata, and Ormosia xylocarpa.

Sox9 Promotes Cardiomyocyte Apoptosis After Acute Myocardial Infarction by Promoting miR-223-3p and Inhibiting MEF2C

Acute myocardial infarction (AMI) is a severe and even fatal cardiovascular disease. The effect of transcription factors on AMI is intensively explored. Our experiment attempts to probe the role of Sox9 in cardiomyocyte apoptosis after AMI. AMI cell model was established in AC16 cells by hypoxia treatment. Cell viability and apoptosis were assessed. Then, the levels of BAX, Bcl-2, Sox9, miR-223-3p, and MEF2C were detected. The binding relation between Sox9 and miR-223-3p and between miR-223-3p and MEF2C was verified. The expression of miR-223-3p was upregulated using the miR-223-3p mimic, and collaborative experiments were conducted as si-Sox9 or si-MEF2C was transfected into cells to inhibit the expression of Sox9 or MEF2C. Sox9 was highly expressed in cardiomyocyte apoptosis after hypoxia, while Sox9 silencing protected hypoxia-treated cardiomyocytes from apoptosis by enhancing cell viability, quenching apoptosis, and reducing activity of caspase-3 and caspase-9. Essentially, Sox9 bound to the miR-223-3p promoter region to upregulate its expression. miR-223-3p targeted MEF2C transcription. miR-223-3p overexpression and MEF2C silencing could counteract the suppressive role of Sox9 silencing in hypoxia-treated cardiomyocyte apoptosis. Sox9 exacerbated hypoxia-induced cardiomyocyte apoptosis by promoting miR-223-3p expression and inhibiting MEF2C transcription.

The truncated TNL receptor TN2-mediated immune responses require ADR1 function

The loss of function of exocyst subunit EXO70B1 leads to autoimmunity, which is dependent on TIR-NBS2 (TN2), a truncated intracellular nucleotide-binding and leucine-rich repeat receptor (NLR). However, how TN2 triggers plant immunity and whether typical NLRs are required in TN2-activated resistance remain unclear. Through the CRISPR/Cas9 gene editing system and knockout analysis, we found that the spontaneous cell death and enhanced resistance in exo70B1-3 were independent of the full-length NLR SOC3 and its closest homolog SOC3-LIKE 1 (SOC3-L1). Additionally, knocking out SOC3-L1 or TN2 did not suppress the chilling sensitivity conferred by chilling sensitive 1-2 (chs1-2). The ACTIVATED DISEASE RESISTANCE 1 (ADR1) family and the N REQUIREMENT GENE 1 (NRG1) family have evolved as helper NLRs for many typical NLRs. Through CRISPR/Cas9 gene editing methods, we discovered that the autoimmunity of exo70B1-3 fully relied on ADR1s, but not NRG1s, and ADR1s contributed to the upregulation of TN2 transcript levels in exo70B1-3. Furthermore, overexpression of TN2 also led to ADR1-dependent autoimmune responses. Taken together, our genetic analysis highlights that the truncated TNL protein TN2-triggered immune responses require ADR1s as helper NLRs to activate downstream signaling, revealing the importance and complexity of ADR1s in plant immunity regulation.

Profile and early outcomes of surgical reconstruction of coronary artery atresia in children

OBJECTIVES

Coronary artery atresia is a rare coronary artery anomaly in children and has a high rate of misdiagnosis. We aimed to summarize the profile and early outcomes after the surgical reconstruction of coronary artery atresia in children.

METHODS

A retrospective analysis was performed in 12 consecutive patients with coronary artery atresia who were admitted to the Department of Paediatric Cardiac Surgery of Fuwai Hospital between October 2016 and September 2020. Ten patients underwent surgical reconstruction of the coronary artery with the pulmonary artery anterior wall, and 8 patients underwent concomitant mitral valvuloplasty.

RESULTS

There were 6 females and 6 males, with an age of 1.75 years [interquartile range (IQR), 1.0-3.5] and weight of 10.0 kg (IQR, 8.9-14.75). There were 10 cases of left coronary artery atresia and 2 cases of right coronary artery atresia. All the patients were initially misdiagnosed in the outpatient clinic, but further nonselective coronary angiography confirmed the diagnosis of coronary artery atresia. In all 10 patients with mitral regurgitation, echocardiogram of the mitral valve chordae and papillary muscle revealed ischaemic changes. The clamp time was 89.0 min (IQR, 75.0-101.0), the pump time was 126.0 min (IQR, 119.0-132.0) and the intensive care unit stay time was 1.5 days (IQR, 1.0-3.0). No perioperative deaths were noted. After 9.5 months (IQR, 5.5-13.5) of follow-up, 2 patients with fractional shortening that significantly decreased to 14.1% and 14.8% died and 1 patient had moderate pericardial effusion that improved after treatment with oral diuretics. Coronary artery ultrasound and enhanced computed tomography showed a patent main coronary artery in all the patients.

CONCLUSIONS

Coronary artery atresia in children is often associated with mitral regurgitation, and mitral valve chordae and papillary muscle exhibit ischaemic changes. Coronary artery reconstruction is safe and effective in children with coronary artery atresia.

The TIR-NBS protein TN13 associates with the CC-NBS-LRR resistance protein RPS5 and contributes to RPS5-triggered immunity in Arabidopsis

Nucleotide-binding site (NBS)-leucine-rich repeat (LRR) domain receptor (NLR) proteins play important roles in plant innate immunity by recognizing pathogen effectors. The Toll/interleukin-1 receptor (TIR)-NBS (TN) proteins belong to a subtype of the atypical NLRs, but their function in plant immunity is poorly understood. The well-characterized Arabidopsis thaliana typical coiled-coil (CC)-NBS-LRR (CNL) protein Resistance to Pseudomonas syringae 5 (RPS5) is activated after recognizing the Pseudomonas syringae type III effector AvrPphB. To explore whether the truncated TN proteins function in CNL-mediated immune signaling, we examined the interactions between the Arabidopsis TN proteins and RPS5, and found that TN13 and TN21 interacted with RPS5. However, only TN13, but not TN21, was involved in the resistance to P. syringae pv. tomato (Pto) strain DC3000 carrying avrPphB, encoding the cognate effector recognized by RPS5. Moreover, the regulation of Pto DC3000 avrPphB resistance by TN13 appeared to be specific, as loss of function of TN13 did not compromise resistance to Pto DC3000 hrcC^- or Pto DC3000 avrRpt2. In addition, we demonstrated that the CC and NBS domains of RPS5 play essential roles in the interaction between TN13 and RPS5. Taken together, our results uncover a direct functional link between TN13 and RPS5, suggesting that TN13 acts as a partner in modulating RPS5-activated immune signaling, which constitutes a previously unknown mechanism for TN-mediated regulation of plant immunity.

The Fate of Congenitally Corrected Transposition of the Great Arteries Unoperated Before Adulthood

BACKGROUND

The outcomes, therapeutic strategies, and risk factors of congenital corrected transposition of great arteries (ccTGA) unoperated before adulthood are unclear.

METHODS

From October 2009 to January 2018, 117 adult ccTGA patients, classified into ccTGA with intact ventricular septum, ventricular septum defect, and pulmonary valve or subpulmonary outflow tract stenosis (PS) groups, were reviewed. Statistical analysis was performed with SPSS 19.0 (IBM, Armonk, NY).

RESULTS

At the first visit, no patients suffered operation. The PS group had the least systemic atrioventricular valve regurgitation and the greatest systemic ventricular ejection fraction. All 49 patients underwent surgery. From the first visit to last follow-up, systemic ventricular ejection fraction of unoperated ccTGA decreased significantly. In the intact ventricular septum group, patients receiving systemic atrioventricular valve replacement/valvuloplasty had a significantly increased systemic ventricular ejection fraction and statistically more freedom from death and transplant than unoperated. In the ventricular septum defect group the late systemic ventricular ejection fraction of operated patients was not statistically different from their basic data at first visit. In the PS group patients receiving physiologic repair had significantly decreased systemic ventricular ejection fractions. Severe systemic atrioventricular valve regurgitation, physiologic repair, and systemic ventricular dysfunction (ejection fraction <40%) were risk factors for mortality, transplant, and congestive heart failure.

CONCLUSIONS

PS protects against systemic atrioventricular valve regurgitation and ventricular dysfunction. Systemic atrioventricular valve replacement/valvuloplasty improved systemic ventricular function for ccTGA with an intact ventricular septum. Physiologic repair was not ideal for ccTGA with PS. Severe systemic atrioventricular valve regurgitation and systemic ventricular dysfunction were associated with suboptimal outcomes.

Absorbable Microplate Externally Suspending Bronchomalacia in Congenital Heart Disease Infant

To evaluate the feasibility and efficacy of external suspension with absorbable poly-l-lactic acid material shaping microplates for infants with severe bronchomalacia and congenital heart disease. From November 2017 to January 2019, 11 continual patients with severe bronchomalacia and congenital heart disease underwent bronchial membrane external suspension together with cardiovascular surgery. An absorbable plate made with poly-l-lactic acid material was used as the shaping fixation material in all patients. Data included the details of the operation, and clinical results were collected. The mean age was 1.2 ± 1.0 years, and the mean weight was 7.7 ± 2.9 kg. The patients with cardiac malformations were operated on under low-temperature cardiopulmonary bypass (CPB) through median sternotomy. There were no in-hospital deaths. The CPB time, mechanical ventilation time, and length of intensive care unit stay were 123.9 ± 36.9 min, 20.7 ± 19.4 h, and 71.6 ± 54.9 h, respectively. Two patients underwent surgery through a left posterolateral incision without CPB. One was a double aortic arch repair, and the other was only bronchial membrane external suspension with prior IAA repair. No patients needed ECMO support. The mean follow-up time was 12.1 ± 5.6 months, and no patients were lost to follow-up. No cases of late death were noted, and no patients needed reoperation. According to the CT scans, no patients had bronchial restenosis. External bronchial membrane suspension with an absorbable poly-l-lactic acid material shaping plate, which had better histocompatibility, for infants with severe bronchomalacia and congenital heart disease was a safe and feasible procedure.

Pediatric Mitral Regurgitation: Standardized Repair-Oriented Strategy With Leaflet Plication

To introduce a standardized strategy and reproducible procedures of mitral repair for mitral regurgitation in the pediatric population with leaflet plication as a principal technique. Consecutive patients who had undergone mitral repair by our standardized repair-oriented strategy in our institution from January 2016 to December 2019 were included retrospectively. The standardized repair strategy included 3-step inspections and repair from the subvalvular to leaflet, and then to the annular level. The main surgical techniques included chordae detachment, papillary muscle splitting, leaflet plication, and posterior annuloplasty. The indication for leaflet plication was that the distance between 2 adjacent chordae tendineae was greater than 4 mm. A total of 113 patients were enrolled. During 22.6-month (range, 2-50 months) follow-up period, primary endpoint was documented in 15 (13.3%) patients, including 1 (0.9%) death, 0 transplantation, and 14 (12.4%) functional mitral failure. Freedom form primary endpoints at 6 months, 1 year, and 3 years was 94.7%, 94.7%, and 82.3%, respectively. Significant independent predictors of functional mitral valve failure were younger age (hazard ratio [HR], 0.28; 95% confidence interval [CI], 0.04-0.72; P = 0.037) and ischemic mitral regurgitation (MR) (HR, 24.34; 95% CI, 4.52-47.33; P < 0.001). Leaflet plication was significantly associated with well-functioned mitral valve (HR, 7.42; 95% CI, 2.35-30.54; P = 0.004). Compared with nonischemic MR group, ischemic MR group was noted with higher occurrence of primary endpoint events (11/28 vs 4/85, P < 0.001). The short- to mid-term outcomes of standardized mitral repair technique with leaflet plication were favorable, among which, however, repair for mitral regurgitation with ischemic lesions is comparatively challenging.

OP0316 EMERGING BEST-IN-CLASS IL-2 VARIANT HIGHLIGHTS TREG-DIRECTED THERAPY FOR AUTOIMMUNE DISEASE

Background:

Impairment or deficiency of regulatory T cells (Treg) is associated with chronic inflammation and autoimmune diseases. Interleukin 2 (IL-2) is a cytokine indispensable for Treg expansion and immunosuppressive function. However, expansion of cytotoxic effector T (Teff) and NK cells and the associated vascular leakage side effect limit the use of IL-2 in autoimmune diseases [1].

Objectives:

Cugene developed a long-acting IL-2 variant with high Treg specificity and low toxicity to restore immune homeostasis and self-tolerance, and potentially cure autoimmune and inflammatory diseases.

Methods:

IL-2 variants were generated based on the quaternary structure of IL-2 and IL-2Rαβγ (alpha, beta, gamma) complex. Biological activity was determined by examining differential signaling activity in induction of STAT5 phosphorylation in defined lymphocyte populations of human PBMC using flow cytometry. Binding activity was evaluated by ELISA. Pharmacokinetics, pharmacodynamics, safety and tolerability were assessed in mice and cynomolgus monkeys. Treg suppressive function was determinedin vivo/ex vivo,and anti-inflammatory and anti-antibody production efficacy were determined in delayed-type hypersensitivity (DTH) and T-cell-dependent antibody response (TDAR) models.

Results:

Structure-based rational design and activity-guided fine-tuning generated an optimized IL-2 variant, CUG252. It demonstrated a strong and near wild-type IL-2 ability to stimulate STAT5 phosphorylation in IL-2Rαβγ dominant Treg cells but abolished activities in IL-2Rβγ dominant effector CD4, CD8 and NK cells. This was a result of biased binding activity to IL-2Rα while dramatically attenuated binding to IL-2Rβγ complex. In mice and monkeys, administration of CUG252 resulted in dose-dependent increases in Treg proliferation and expansion by more than 10- and 30-fold, respectively, with largely abolished activities in CD4+ T conventional, cytotoxic CD8+ Teff and NK cells. The ratio of Treg/Teff cells achieved was as high as 0.4 in mice and 1.2 in monkeys. Both CD4+ and CD8+ Tregs were expanded with preferential increases in memory over naïve subsets. A substantial increase in Treg-suppressive capacity over T effector cells was corroborated by enhanced expression of functional and inhibitory markers, including CD25, Foxp3, PD-1, CTLA-4, Tim3 and ICOS. In DTH and TDAR models, CUG252 strongly inhibited antigen-driven inflammation, B cell maturation, and antibody production. The sustained PK/PD profile supports monthly dosing or better in humans. CUG252 was well-tolerated and no changes in body weight, body temperature, clinical pathology or signs of vascular leakage were observed. Moreover, CUG252 demonstrated superior manufacturability.

Conclusion:

CUG252 demonstrates an emerging best-in-class profile among IL-2 variants. It displayed exquisite Treg-selectivity while retaining potency comparable to wild-type IL-2. It showed strong anti-inflammatory and anti-antibody production efficacy with significantly improved therapeutic index and manufacturability. Its favorable drug-like property and robust preclinical efficacy warrant further evaluation in patients with a variety of inflammation and autoimmune diseases.

References:

[1]Tahvildari M. et al. Low-Dose IL-2 Therapy in Transplantation, Autoimmunity, and Inflammatory Diseases. J Immunol. 2019; 203: 2749-2755

Disclosure of Interests:

Yao-te Hsieh Employee of: Cugene INC., CEDRIC HUBEAU Employee of: Cugene INC., Virginia MASSA Employee of: Cugene INC., WEN Li Employee of: Cugene INC., SANDRA FREI Employee of: Cugene INC., BEN CAPRARO Employee of: Cugene INC., ANDREA UMANA Employee of: Cugene INC., ANDREW AHERRERA Employee of: Cugene INC., YUESHENG LI Employee of: Cugene INC., JING XU Employee of: Cugene INC., LINGYUN RUI Employee of: Cugene INC.

Through Tricuspid Closure for Doubly Committed Subarterial Ventricular Septal Defect with Right Vertical Subaxillary Mini-incision: A Matched-Pair Analysis

To evaluate the feasibility and efficacy of the right subaxillary vertical mini-incision (RAVI) used for the closure of doubly committed subarterial ventricular septal defect (SAVSD) through tricuspid approach only. From June 2015 to September 2016, 32 SAVSD patients (mean age 2.4 ± 1.9 years, range 0.7-8 years) underwent surgical repair with either RAVI (incision length 3-4 cm) through tricuspid (group A, n = 16) or conventional median sternotomy incision through the main pulmonary artery approach (group B, n = 16). A retrospective 1:1 matched-pair analysis was performed with the group B matched for defect size, body weight, gender, patching, and operation year. The demographic characteristics in both groups were similar. No patient died and only 1 patient in group B needed reoperation for sternal infection. The mean cardiopulmonary bypass (CPB) time and aortic cross-clamp time were 48.6 ± 12.6 min, 29.3 ± 8.5 min in the group A and 57.8 ± 14.1 min (p = 0.03), 34.3 ± 12.1 min ( p = 0.18) in the group B. There was no significant difference between the two groups in the ICU stay (17.8 ± 8.9 h in group A, 18.7 ± 9.5 h in group B, p = 0.79), mechanical ventilation support time (2.7 ± 1.7 h in group A, 3.6 ± 1.5 h in group B, p = 0.11), postoperative hospital stay (6.3 ± 1.5 days in group A, 7.4 ± 1.7 days in group B, p = 0.06), and chest tube drainage (6.4 ± 4.3 ml/kg in group A, 8.5 ± 3.8 ml/kg in group B, p = 0.16). No significant residual defects were found in both groups. The post-operation pressure gradient across the right ventricular outflow tract (RVOT) was significantly different between the two groups with 4.6 ± 1.8 mmHg in group A and 10.0 ± 6.8 mmHg in group B (p = 0.004) even if no significant difference was found between both groups before operation. No arrhythmia was found after operation. All the patients or the parents (100%) in the group A were satisfied with the cosmetic results, while the number in B group was 7 (43.8%) in questionnaire. The RAVI through tricuspid approach to repair doubly committed subarterial ventricular septal defect is a safe and feasible procedure with better hemodynamic performance of RVOT and less CPB time because of keeping pulmonary artery intact comparing to conventional approach. More importantly, the RAVI through tricuspid approach can be performed with favorable cosmetic results.

The Pseudomonas Syringae Effector AvrPtoB Associates With and Ubiquitinates Arabidopsis Exocyst Subunit EXO70B1

Many bacterial pathogens secret effectors into host cells to disable host defenses and thus promote infection. The exocyst complex functions in the transport and secretion of defense molecules, and loss of function of the EXO70B1 subunit leads to autoimmunity by activation of a truncated Toll/interleukin-1 receptor-nucleotide-binding sequence protein (TIR-NBS2; herein referred to as TN2). Here, we show that EXO70B1 is required for pathogen-associated molecular pattern-triggered immune responses in Arabidopsis thaliana. The effector AvrPtoB, an E3 ligase from Pseudomonas syringae pv. tomato (Pto) strain DC3000, associates with EXO70B1. AvrPtoB ubiquitinates EXO70B1 and mediates EXO70B1 degradation via the host's 26S proteasome in a manner requiring E3 ligase activity. AvrPtoB enhances Pto DC3000 virulence by overcoming EXO70B1-mediated resistance. Moreover, overexpression of AvrPtoB in Arabidopsis leads to autoimmunity, which is partially dependent on TN2. Expression of TN2 in tobacco (Nicotiana tabacum and Nicotiana benthamiana) triggers strong and rapid cell death, which is suppressed by co-expression with EXO70B1 but reoccurs when co-expressed with AvrPtoB. Taken together, our data highlight that AvrPtoB targets the Arabidopsis thaliana EXO70 protein family member EXO70B1 to manipulate the defense molecule secretion machinery or immunity.

The major leaf ferredoxin Fd2 regulates plant innate immunity in Arabidopsis

Ferredoxins, the major distributors for electrons to various acceptor systems in plastids, contribute to redox regulation and antioxidant defence in plants. However, their function in plant immunity is not fully understood. In this study, we show that the expression of the major leaf ferredoxin gene Fd2 is suppressed by Pseudomonas syringae pv. tomato (Pst) DC3000 infection, and that knockout of Fd2 (Fd2-KO) in Arabidopsis increases the plant's susceptibility to both Pst DC3000 and Golovinomyces cichoracearum. On Pst DC3000 infection, the Fd2-KO mutant accumulates increased levels of jasmonic acid and displays compromised salicylic acid-related immune responses. Fd2-KO also shows defects in the accumulation of reactive oxygen species induced by pathogen-associated molecular pattern-triggered immunity. However, Fd2-KO shows enhanced R-protein-mediated resistance to Pst DC3000/AvrRpt2 infection, suggesting that Fd2 plays a negative role in effector-triggered immunity. Furthermore, Fd2 interacts with FIBRILLIN4 (FIB4), a harpin-binding protein localized in chloroplasts. Interestingly, Fd2, but not FIB4, localizes to stromules that extend from chloroplasts. Taken together, our results demonstrate that Fd2 plays an important role in plant immunity.

FBXO10 deficiency and BTK activation upregulate BCL2 expression in mantle cell lymphoma

Targeting Bruton tyrosine kinase (BTK) by ibrutinib is an effective treatment for patients with relapsed/refractory mantle cell lymphoma (MCL). However, both primary and acquired resistance to ibrutinib have developed in a significant number of these patients. A combinatory strategy targeting multiple oncogenic pathways is critical to enhance the efficacy of ibrutinib. Here, we focus on the BCL2 anti-apoptotic pathway. In a tissue microarray of 62 MCL samples, BCL2 expression positively correlated with BTK expression. Increased levels of BCL2 were shown to be due to a defect in protein degradation because of no or little expression of the E3 ubiquitin ligase FBXO10, as well as transcriptional upregulation through BTK-mediated canonical nuclear factor-κB activation. RNA-seq analysis confirmed that a set of anti-apoptotic genes (for example, BCL2, BCL-XL and DAD1) was downregulated by BTK short hairpin RNA. The downregulated genes also included those that are critical for B-cell growth and proliferation, such as BCL6, MYC, PIK3CA and BAFF-R. Targeting BCL2 by the specific inhibitor ABT-199 synergized with ibrutinib in inhibiting growth of both ibrutinib-sensitive and -resistant cancer cells in vitro and in vivo. These results suggest co-targeting of BTK and BCL2 as a new therapeutic strategy in MCL, especially for patients with primary resistance to ibrutinib.

A mix of S and ΔS variants of STAT3 enable survival of activated B-cell-like diffuse large B-cell lymphoma cells in culture

Activated B-cell-like diffuse large B-cell lymphoma (ABC DLBCL) is characterized by increased expression and activator of signal transducer and activator of transcription 3 (STAT3). ABC DLBCL cells require STAT3 for growth in culture. In ABC DLBCL cells, eosinophils and perhaps all cells, four variant STAT3 mRNAs (Sα, ΔSα, Sβ and ΔSβ) are present as a result of two alternative splicing events, one that results in the inclusion of a 55-residue C-terminal transactivation domain (α) or a truncated C-terminal domain with 7 unique residues (β) and a second that includes (S) or excludes (ΔS) the codon for Ser-701 in the linker between the SH2 and C-terminal domains. A substantial literature indicates that both α and β variants are required for optimal STAT3 function, but nothing is known about functions of ΔS variants. We used a knockdown/re-expression strategy to explore whether survival of ABC DLBCL cells requires that the four variants be in an appropriate ratio. No single variant rescued survival as well as STAT3Sα-C, Sα with activating mutations (A661C and N663C) in the SH2 domain. Better rescue was achieved when all four variants were re-expressed or Sα and ΔSα or Sβ and ΔSβ were re-expressed in pairs. Rescue correlated with expression of STAT3-sensitive genes NFKBIA and NFKBIZ. We consider a variety of explanations why a mix of S and ΔS variants of STAT3 should enable survival of ABC DLBCL cells.

Relationships between transient elastography values and liver fibrosis in chronic liver disease patients with normal or mildly abnormal aminotransferase levels

This study aimed to evaluate relationships between transient elastography values and liver fibrosis in chronic liver disease patients with normal or mildly abnormal aminotransferase levels. Fifty-six patients were enrolled in the study. Transient elastography and liver biopsy were performed on the same day, and the fibrosis was staged based on the Scheuer scoring system. Liver stiffness was measured to assessed liver fibrosis using transient elastography. The transient elastography values of 12 patients with chronic hepatitis B were studied before and 6 months after antiviral treatment. The sensitivity and specificity for 10.88 kPa in S3 were 80 and 87.8%, and for 19.4 kPa in S4, were 100 and 90.7%, respectively. In univariate analysis, liver stiffness strongly correlated with the fibrosis stage (r = 0.70, P < 0.5), moderately correlated with the aminotransferases (r = 0.398, P < 0.05), and poorly correlated with the degree of necroinflammatory activity (r = 0.19, P < 0.5). In multivariate regression, liver stiffness correlated only with the fibrosis stage (P < 0.05). Pre- and post-treatment viral loads were not significantly different [(4.81 ± 0.15) x 10(6) vs (7.62 ± 0. 16) x 10(3), P > 0.05]. Pre- and post-treatment LS measurements were not correlated with viral load (P > 0.05). Pre- and post-treatment LS measurements were not significantly different (P > 0.02). In conclusion, transient elastography values correlated with the stage of cirrhosis, alanine aminotransferase levels, and antiviral treatment in patients with chronic hepatitis B and did not correlate with viral loads.

Hepatitis B virus can be inhibited by DNA methyltransferase 3a via specific zinc-finger-induced methylation of the X promoter

In this work we explored whether DNA methyltransferase 3a (Dnmt3a) targeted to the HBV X promoter (XP) causes epigenetic suppression of hepatitis B virus (HBV). The C-terminus of Dnmt3a (Dnmt3aC) was fused to a six-zinc-finger peptide specific to XP to form a fused DNA methyltransferase (XPDnmt3aC). The binding and methyl-modifying specificity of XPDnmt3aC were verified with an electrophoretic mobility shift assay and methylation-specific PCR, respectively. XP activity and HBV expression were clearly downregulated in HepG2 cells transfected with plasmid pXPDnmt3aC. The injection of XPDnmt3aC into HBV transgenic (TgHBV) mice also showed significant inhibition, leading to low serum HBV surface protein (HBsAg) levels and a reduced viral load. Thus, XPDnmt3aC specifically silenced HBV via site-selective DNA methylation delivered by zinc-finger peptides. This study establishes the foundation of an epigenetic way of controlling HBV-related diseases.

A truncated NLR protein, TIR-NBS2, is required for activated defense responses in the exo70B1 mutant

During exocytosis, the evolutionarily conserved exocyst complex tethers Golgi-derived vesicles to the target plasma membrane, a critical function for secretory pathways. Here we show that exo70B1 loss-of-function mutants express activated defense responses upon infection and express enhanced resistance to fungal, oomycete and bacterial pathogens. In a screen for mutants that suppress exo70B1 resistance, we identified nine alleles of TIR-NBS2 (TN2), suggesting that loss-of-function of EXO70B1 leads to activation of this nucleotide binding domain and leucine-rich repeat-containing (NLR)-like disease resistance protein. This NLR-like protein is atypical because it lacks the LRR domain common in typical NLR receptors. In addition, we show that TN2 interacts with EXO70B1 in yeast and in planta. Our study thus provides a link between the exocyst complex and the function of a 'TIR-NBS only' immune receptor like protein. Our data are consistent with a speculative model wherein pathogen effectors could evolve to target EXO70B1 to manipulate plant secretion machinery. TN2 could monitor EXO70B1 integrity as part of an immune receptor complex.

Evaluation and selection of indicators for land degradation and desertification monitoring: types of degradation, causes, and implications for management

Indicator-based approaches are often used to monitor land degradation and desertification from the global to the very local scale. However, there is still little agreement on which indicators may best reflect both status and trends of these phenomena. In this study, various processes of land degradation and desertification have been analyzed in 17 study sites around the world using a wide set of biophysical and socioeconomic indicators. The database described earlier in this issue by Kosmas and others (Environ Manage, 2013) for defining desertification risk was further analyzed to define the most important indicators related to the following degradation processes: water erosion in various land uses, tillage erosion, soil salinization, water stress, forest fires, and overgrazing. A correlation analysis was applied to the selected indicators in order to identify the most important variables contributing to each land degradation process. The analysis indicates that the most important indicators are: (i) rain seasonality affecting water erosion, water stress, and forest fires, (ii) slope gradient affecting water erosion, tillage erosion and water stress, and (iii) water scarcity soil salinization, water stress, and forest fires. Implementation of existing regulations or policies concerned with resources development and environmental sustainability was identified as the most important indicator of land protection.

Evaluation and selection of indicators for land degradation and desertification monitoring: methodological approach

An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment, socio-economic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score to desertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient, plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.

Anti-interleukin-12/23p40 antibody attenuates chronic rejection of cardiac allografts partly via inhibition γδT cells

In our previous study, we showed that treatment with an anti-interleukin (IL)-12/23p40 antibody inhibits acute cardiac allograft rejection via inhibiting production of interferon (IFN)-γ and IL-17a. However, the impact of this antagonistic anti-p40 antibody on chronic cardiac rejection was unclear. Hearts of B6.C-H2bm12/KhEg mice were transplanted into major histocompatibility complex (MHC) class II-mismatched C57Bl/6J mice (wild-type, γδTCR (-/-) and IL-17(-/-) ), which is an established murine model of chronic allograft rejection without immunosuppression. The mice were treated with control immunoglobulin (Ig)G or 200 µg anti-p40 monoclonal antibody on post-operative days, respectively. Abdominal palpation and echocardiography were used to monitor graft survival. The mice administered with anti-p40 antibody showed a significant promotion in graft survival (median survival time >100 days), and histological analyses revealed that cardiac allograft rejection was attenuated. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence analyses demonstrated that anti-p40 antibody down-regulated the level of ingraft cytokine and chemokine expression (IL-6, IFN-γ, IL-17a, CCL2 and CCL20). Flow cytometry analyses showed that γδ T cells are an important ingraft source of IFN-γ and IL-17a and inhibit the production of inflammation cytokine by anti-p40 antibody. Compared with the wild-type group, the graft survival time in the γδ T cell receptor(-/-) and IL-17(-/-) mice was prolonged significantly. Therefore we propose that, in the chronic allograft rejection model, treatment with anti-p40 antibody prolongs graft survival possibly by reducing the amount of reactive inflammatory cells, especially γδ T cells.

Dynamic changes in Th1, Th17, and FoxP3+ T cells in patients with acute cellular rejection after cardiac transplantation

Previously, studies suggest that CD4(+) effector T-cell subsets participate in allograft rejection. However, the dynamic changes and relative roles of these CD4(+) effector T-cell subsets, especially Th17 cells, have not been systemically examined in patients with acute rejection after cardiac transplantation. In this study, we have studied and compared these CD4(+) T-cell subsets in peripheral blood and endomyocardial biopsies (EMB) in patients with stable-graft and acute cellular rejection. We observed that the gene expressions including T-bet, IFN-γ, RORγt, IL-17, IL-23, and FoxP3, the functional marker of Th1, Th17, and FoxP3(+) CD4(+) T cells, were elevated in EMB samples from patients with acute graft rejection. Accordingly, the percentages of circulating Th1, Th17, and FoxP3(+) CD4(+) T cells were also significantly increased. The data suggest that Th1, Th17, and FoxP3(+) CD4(+) T cells are associated with acute graft rejection in patients with cardiac transplantation.

Extracellular hmgb1 functions as an innate immune-mediator implicated in murine cardiac allograft acute rejection

Hmgb1, an evolutionarily conserved chromosomal protein, was recently re-discovered to be an innate immune-mediator contributing to both innate and adaptive immune responses. Here, we show a pivotal role for Hmgb1 in acute allograft rejection in a murine cardiac transplantation model. Extracellular Hmgb1 was found to be a potent stimulator for adaptive immune responses. Hmgb1 can be either passively released from damaged cells after organ harvest and ischemia/reperfusion insults, or actively secreted by allograft infiltrated immune cells. After transplantation, allografts show a significant temporal up-regulation of Hmgb1 expression accompanied by inflammatory infiltration, a consequence of graft destruction. These data suggest the involvement of Hmgb1 in acute allograft rejection. In line with these observations, treatment of recipients with rA-box, a specific blockade for endogenous Hmgb1, significantly prolonged cardiac allograft survival as compared to those recipients treated with either rGST or control vehicle. The enhanced graft survival is associated with reduced allograft expression of TNFalpha, IFNgamma and Hmgb1 and impaired Th1 immune response.

Regulation of insulin/insulin-like growth factor-1 signaling by proteasome-mediated degradation of insulin receptor substrate-2

Insulin and insulin-like growth factor-1 (IGF-1) regulate metabolism and body growth through homologous receptor tyrosine kinases that phosphorylate the insulin receptor substrate (IRS) proteins. IRS-2 is an important IRS protein, as it mediates peripheral insulin action and beta-cell survival. In this study, we show that insulin, IGF-1, or osmotic stress promoted ubiquitin/proteasome-mediated degradation of IRS-2 in 3T3-L1 cells, Fao hepatoma, cells and mouse embryo fibroblasts; however, insulin/IGF-1 did not promote degradation of IRS-1 in 3T3-L1 preadipocytes or mouse embryo fibroblasts. MG132 or lactacystin, specific inhibitors of 26S proteasome, blocked insulin/IGF-1-induced degradation of IRS-2 and enhanced the detection of ubiquitinated IRS-2. Insulin/IGF1-induced ubiquitination and degradation of IRS-2 was blocked by inhibitors of phosphatidylinositol 3-kinase (wortmannin or LY294002) or mTOR (rapamycin). Chronic insulin or IGF-1 treatment of IRS-1-deficient mouse embryo fibroblasts inhibited IRS-2-mediated activation of Akt and ERK1/2, which was reversed by lactacystin pretreatment. By contrast, IRS-1 activation of Akt and ERK1/2 was not inhibited by chronic insulin/IGF-1 stimulation in IRS-2-deficient mouse embryo fibroblasts. Thus, we identified a novel negative feedback mechanism by which the ubiquitin/proteasome-mediated degradation of IRS-2 limits the magnitude and duration of the response to insulin or IGF-1.

Selective determination of dopamine in the presence of ascorbic acid at an over-oxidized poly(N-acetylaniline) electrode

An over-oxidized poly(N-acetylaniline) (PNAANI)/GCE was used to determine dopamine (DA) in a large excess of ascorbic acid (AA) by differential pulse voltammetry. A linear relation between Ip and DA concentration was found over the range 5.0 x 10(-7) to 2.0 x 10(-5) M. The detection limit was 1.68 x 10(-8) M for S/N = 3 and 400 microM AA did not interfere with the DA determination. The high sensitivity was due to accumulation and selectivity was due to charge discrimination. The mechanism of selective determination of DA at over-oxidized PNAANI/GCE was also proposed.

[A comparison between a submerged membrane bioreactor and a conventional activated sludge process]

A comparison between a submerged membrane bioreactor (MBR) and a conventional activated sludge process (CAS) was carried out under similar operational conditions. MBR demonstrated a more stable and excellent effluent quality than CAS. Its effluent COD concentration was 55.5 mg/L on average, much lower than that of CAS (79.7 mg/L). Soluble microbial products accumulated in the MBR during the first 120 days in operation due to membrane interception of macromolecules, but these accumulated substances were degraded at last with microbial acclimation. No similar phenomenon was observed in the CAS system. Compositions of the CAS effluent, MBR supernatant and membrane permeate were found quite different. In the CAS effluent and MBR supernatant, both macromolecules with MW > 60,000 and small molecules with MW < 3,000 were dominant and macromolecules had a much larger occupation in the MBR supernatant. In the membrane permeate, however, small molecules with MW < 3,000 were the major component. The relatively small floc size in the MBR was proved favorable to improve oxygen transfer rate.

Insulin/IGF-1 and TNF-alpha stimulate phosphorylation of IRS-1 at inhibitory Ser307 via distinct pathways

Serine/threonine phosphorylation of IRS-1 might inhibit insulin signaling, but the relevant phosphorylation sites are difficult to identify in cultured cells and to validate in isolated tissues. Recently, we discovered that recombinant NH2-terminal Jun kinase phosphorylates IRS-1 at Ser307, which inhibits insulin-stimulated tyrosine phosphorylation of IRS-1. To monitor phosphorylation of Ser307 in various cell and tissue backgrounds, we prepared a phosphospecific polyclonal antibody designated alphapSer307. This antibody revealed that TNF-alpha, IGF-1, or insulin stimulated phosphorylation of IRS-1 at Ser307 in 3T3-L1 preadipocytes and adipocytes. Insulin injected into mice or rats also stimulated phosphorylation of Ser307 on IRS-1 immunoprecipitated from muscle; moreover, Ser307 was phosphorylated in human muscle during the hyperinsulinemic euglycemic clamp. Experiments in 3T3-L1 preadipocytes and adipocytes revealed that insulin-stimulated phosphorylation of Ser307 was inhibited by LY294002 or wortmannin, whereas TNF-alpha-stimulated phosphorylation was inhibited by PD98059. Thus, distinct kinase pathways might converge at Ser307 to mediate feedback or heterologous inhibition of IRS-1 signaling to counterregulate the insulin response.

Role of the tyrosine kinase JAK2 in signal transduction by growth hormone

Chronic renal failure in children results in impaired body growth. This effect is so severe in some children that not only does it have a negative impact on their self-image, but it also affects their ability to carry out normal day-to-day functions. Yet the mechanism by which chronic renal failure causes short stature is not well understood. Growth hormone (GH) therapy increases body height in prepubertal children, suggesting that a better understanding of how GH promotes body growth may lead to better insight into the impaired body growth in chronic renal failure and therefore better therapies. This review discusses what is currently known about how GH acts at a cellular level. The review discusses how GH is known to bind to a membrane-bound receptor and activate a cytoplasmic tyrosine kinase called Janus kinase (JAK) 2. The activated JAK2 in turn phosphorylates tyrosines within itself and the associated GH receptor, forming high-affinity binding sites for a variety of signaling molecules. Examples of such signaling molecules include signal transducers and activators of transcription (Stats), which regulate the expression of a variety of GH-dependent genes, and the adapter protein Shc, which leads to activation of the Ras-Raf-MEK-MAP kinase pathway. In response to GH, JAK2 is also known to phosphorylate the insulin receptor substrates, leading to activation of phosphatidyl inositol 3' kinase and most likely other molecules that have been implicated in the regulation of metabolism. Finally, the ability of JAK2 to bind and activate the presumed adapter protein SH2-B is discussed. SH2-B has been shown to be a potent activator of GH-promoted JAK2 activity and downstream signaling events. Presumably these and other pathways initiated by GH combine to result in its ability to regulate body growth and metabolism.

Differential binding to and regulation of JAK2 by the SH2 domain and N-terminal region of SH2-bbeta

SH2-Bbeta has been shown to bind via its SH2 (Src homology 2) domain to tyrosyl-phosphorylated JAK2 and strongly activate JAK2. In this study, we demonstrate the existence of an additional binding site(s) for JAK2 within the N-terminal region of SH2-Bbeta (amino acids 1 to 555) and the ability of this region of SH2-B to inhibit JAK2. Four lines of evidence support the existence of this additional binding site(s). In a glutathione S-transferase pull-down assay, wild-type SH2-Bbeta and SH2-Bbeta(R555E) with a defective SH2 domain bind to both tyrosyl-phosphorylated JAK2 from growth hormone (GH)-treated cells and non-tyrosyl-phosphorylated JAK2 from control cells, whereas the SH2 domain of SH2-Bbeta binds only to tyrosyl-phosphorylated JAK2 from GH-treated cells. Similarly, JAK2 is present in alphaSH2-B immunoprecipitates in the absence and presence of GH, with GH substantially increasing the coprecipitation of JAK2 with SH2-B. When coexpressed in COS cells, SH2-Bbeta coimmunoprecipitates not only wild-type, tyrosyl-phosphorylated JAK2 but also kinase-inactive, non-tyrosyl-phosphorylated JAK2(K882E), although to a lesser extent. DeltaC555 (amino acids 1 to 555 of SH2-Bbeta) that lacks most of the SH2 domain binds similarly to wild-type JAK2 and kinase-inactive JAK2(K882E). Experiments using a series of N- and C-terminally truncated SH2-Bbeta constructs indicate that the pleckstrin homology (PH) domain (amino acids 269 to 410) and amino acids 410 to 555 are necessary for maximal binding of SH2-Bbeta to inactive JAK2, but neither region alone is sufficient for maximal binding. The SH2 domain of SH2-Bbeta is necessary and sufficient for the stimulatory effect of SH2-Bbeta on JAK2 and JAK2-mediated tyrosyl phosphorylation of Stat5B. In contrast, DeltaC555 lacking the SH2 domain, and to a lesser extent the PH domain alone, inhibits JAK2. DeltaC555 also blocks JAK2-mediated tyrosyl phosphorylation of Stat5B in COS cells and GH-stimulated nuclear accumulation of Stat5B in 3T3-F442A cells. These data indicate that in addition to the SH2 domain, SH2-Bbeta has one or more lower-affinity binding sites for JAK2 within amino acids 269 to 555. The interaction via this site(s) in SH2-B with inactive JAK2 seems likely to increase the local concentration of SH2-Bbeta around JAK2, thereby facilitating binding of the SH2 domain to ligand-activated JAK2. This would result in a more rapid and robust cellular response to hormones and cytokines that activate JAK2. This interaction between inactive JAK2 and SH2-B may also help prevent abnormal activation of JAK2.

SH2-B is required for growth hormone-induced actin reorganization

The Src homology-2 (SH2) domain-containing protein SH2-Bbeta is a substrate of the growth hormone (GH) receptor-associated tyrosine kinase JAK2. Here we tested whether SH2-Bbeta is involved in GH regulation of the actin cytoskeleton. Based on cell fractionation and confocal microscopy, we find SH2-Bbeta present at the plasma membrane and in the cytosol. SH2-Bbeta colocalized with filamentous actin in GH and platelet-derived growth factor (PDGF)-induced membrane ruffles. To test if SH2-Bbeta is required for actin reorganization, we transiently overexpressed wild-type or mutant SH2-Bbeta in 3T3-F442A cells and assayed for GH- and PDGF-induced membrane ruffling and fluid phase pinocytosis. Overexpression of wild-type SH2-Bbeta enhanced ruffling and pinocytosis produced by submaximal GH but not submaximal PDGF. Point mutant SH2-Bbeta (R555E) and truncation mutant DeltaC555, both lacking a functional SH2 domain, inhibited membrane ruffling and pinocytosis induced by GH and PDGF. Mutant DeltaN504, which possesses a functional SH2 domain and enhances JAK2 kinase activity in overexpression systems, also inhibited GH-stimulated membrane ruffling. DeltaN504 failed to inhibit GH-induced nuclear localization of Stat5B, indicating JAK2 is active in these cells. Taken together, these results show that SH2-Bbeta is required for GH-induced actin reorganization by a mechanism discrete from the action of SH2-Bbeta as a stimulator of JAK2 kinase activity.

Platelet-derived growth factor and lysophosphatidic acid inhibit growth hormone binding and signaling via a protein kinase C-dependent pathway

Growth hormone (GH) regulates body growth and metabolism. GH exerts its biological action by stimulating JAK2, a GH receptor (GHR)-associated tyrosine kinase. Activated JAK2 phosphorylates itself and GHR, thus initiating multiple signaling pathways. In this work, we demonstrate that platelet-derived growth factor (PDGF) and lysophosphatidic acid (LPA) down-regulate GH signaling via a protein kinase C (PKC)-dependent pathway. PDGF substantially reduces tyrosyl phosphorylation of JAK2 induced by GH but not interferon-gamma or leukemia inhibitory factor. PDGF, but not epidermal growth factor, decreases tyrosyl phosphorylation of GHR (by approximately 90%) and the amount of both total cellular GHR (by approximately 80%) and GH binding (by approximately 70%). The inhibitory effect of PDGF on GH-induced tyrosyl phosphorylation of JAK2 and GHR is abolished by depletion of 4beta-phorbol 12-myristate 13-acetate (PMA)-sensitive PKCs with chronic PMA treatment and is severely inhibited by GF109203X, an inhibitor of PKCs. In contrast, extracellular signal-regulated kinases 1 and 2 and phosphatidylinositol 3-kinase appear not to be involved in this inhibitory effect of PDGF. LPA, a known activator of PKC, also inhibits GH-induced tyrosyl phosphorylation of JAK2 and GHR and reduces the number of GHR. We propose that ligands that activate PKC, including PDGF, LPA, and PMA, down-regulate GH signaling by decreasing the number of cell surface GHR through promoting GHR internalization and degradation and/or cleavage of membrane GHR and release of the extracellular domain of GHR.

SH2-B and SIRP: JAK2 binding proteins that modulate the actions of growth hormone

Growth hormone (GH) has long been known to be a primary determinant of body height and an important regulator of body metabolism, yet the cellular and molecular bases for these effects of GH are only beginning to be understood. In 1993, GH receptor (GHR) was first observed to bind to the tyrosine kinase JAK2. GH increased JAK2's affinity for GHR, potently activated JAK2, and stimulated the phosphorylation of tyrosines within JAK2 and the cytoplasmic domain of GHR. In the intervening six years, a variety of signaling molecules have been identified that are tyrosyl phosphorylated in response to GH, presumably by the activated JAK2. These signaling molecules include 1) the latent cytoplasmic transcription factors--designated signal transducers and activators of transcription (Stats)--that have been implicated in the regulation of a variety of GH-dependent genes; 2) Shc proteins that lead to activation of the Ras-MAP kinase pathway: and 3) insulin receptor substrate (IRS) proteins that bind and thereby activate phosphatidylinositol 3' kinase and presumably other proteins. Recently, we have identified two additional signaling molecules for GH that bind to JAK2 and are phosphorylated on tyrosines in response to GH: SH2-B and signal regulated protein (SIRP). Based upon amino acid sequence analysis, SH2-B is presumed to be a cytoplasmic adapter protein. It binds with high affinity via its SH2 domain to phosphorylated tyrosines within JAK2. GH-induced binding of SH2-B to JAK2 via this site potently activates JAK2, leading to enhanced tyrosyl phosphorylation of Stat proteins and other cellular proteins. Because of its other potential protein-protein interaction domains and its recruitment and phosphorylation by kinases that are not activated by SH2-B, SH2-B is thought likely to mediate other, more-specific actions of GH, as yet to be determined. SIRP is a transmembrane protein that is now known to bind to integrin-associated protein. It appears to bind directly to JAK2 by a process that does not require tyrosyl phosphorylation, although is itself highly phosphorylated on tyrosines in response to GH. The phosphorylated SIRP recruits one or more molecules of the tyrosine phosphatase SHP2 that, in turn, de-phosphorylates SIRP and most likely JAK2. Thus, SIRP is predicted to be a negative regulator of GH action. It seems likely that the diverse actions of GH will be found to require coordinated interaction of all of these signaling proteins with each other as well as with other signaling molecules that are activated by GH and the numerous other ligands that are present at cells during a response to GH.

SH2-B, a membrane-associated adapter, is phosphorylated on multiple serines/threonines in response to nerve growth factor by kinases within the MEK/ERK cascade

SH2-B has been shown to be required for nerve growth factor (NGF)-mediated neuronal differentiation and survival, associate with NGF receptor TrkA, and be tyrosyl-phosphorylated in response to NGF. In this work, we examined whether NGF stimulates phosphorylation of SH2-B on serines/threonines. NGF promotes a dramatic upward shift in mobility of SH2-B, resulting in multiple forms that cannot be attributed to tyrosyl phosphorylation. Treatment of SH2-B with protein phosphatase 2A, a serine/threonine phosphatase, reduces the many forms to two. PD98059, a MEK inhibitor, dramatically inhibits NGF-promoted phosphorylation of SH2-B on serines/threonines, whereas depletion of 4beta-phorbol 12-myristate 13-acetate-sensitive protein kinase Cs does not. ERKs 1 and 2 phosphorylate SH2-Bbeta primarily on Ser-96 in vitro. However, NGF still stimulates serine/threonine phosphorylation of SH2-Bbeta(S96A). SH2-Bbeta(S96A), like wild-type SH2-Bbeta, enhances NGF-induced neurite outgrowth. In contrast, SH2-Bbeta(R555E) containing a defective SH2 domain blocks NGF-induced neurite outgrowth and displays greatly reduced phosphorylation on serines/threonines in response to NGF. SH2-Bbeta(R555E), like wild-type SH2-Bbeta, associates with the plasma membrane, suggesting that the dominant negative effect of SH2-Bbeta(R555E) cannot be explained by an abnormal subcellular distribution. In summary, NGF stimulates phosphorylation of SH2-B on serines/threonines by kinases downstream of MEK, which may be important for NGF-mediated neuronal differentiation and survival.

Identification of SH2-bbeta as a potent cytoplasmic activator of the tyrosine kinase Janus kinase 2

Janus kinases (JAKs) are cytoplasmic tyrosine kinases critical for signaling by growth hormone (GH) and many other ligands that bind to members of the cytokine receptor superfamily. SH2-Bbeta was previously identified as a JAK2-interacting protein that is tyrosyl phosphorylated in response to GH and other cytokines that activate JAK2. In this study, we examined whether SH2-Bbeta alters the activity of JAK2. SH2-Bbeta, when coexpressed with JAK2, significantly increased the tyrosyl phosphorylation of JAK2 and multiple other cellular proteins and stimulated the kinase activity of JAK2 by approximately 20-fold. Coexpression of SH2-Bbeta with JAK2 dramatically increased tyrosyl phosphorylation of signal transducer and activator of transcription (Stat)5B and Stat3, physiological substrates of JAK2. SH2-Bbeta(R555E) with a defective Src homology 2 domain was unable to stimulate JAK2 and JAK2-mediated tyrosyl phosphorylation of Stat5B and Stat3. More importantly, SH2-Bbeta enhanced GH-induced tyrosyl phosphorylation of endogenous JAK2 and ligand-induced tyrosyl phosphorylation of Stat5B by endogenous JAK2. In contrast, SH2-Bbeta did not potentiate the activation of other tyrosine kinases including the receptors for platelet-derived growth factor, epidermal growth factor, or nerve growth factor (TrkA), tyrosine kinases that also bind SH2-Bbeta. These data demonstrate that SH2-Bbeta is a potent cytoplasmic activator of JAK2 and is thereby expected to be an important cellular regulator of signaling by GH and other hormones and cytokines that activate JAK2.

SH2-B is required for nerve growth factor-induced neuronal differentiation

Nerve growth factor (NGF) is essential for the development and survival of sympathetic and sensory neurons. NGF binds to TrkA, activates the intrinsic kinase activity of TrkA, and promotes the differentiation of pheochromocytoma (PC12) cells into sympathetic-like neurons. Several signaling molecules and pathways are known to be activated by NGF, including phospholipase Cgamma, phosphatidylinositol-3 kinase, and the mitogen-activated protein kinase cascade. However, the mechanism of NGF-induced neuronal differentiation remains unclear. In this study, we examined whether SH2-Bbeta, a recently identified pleckstrin homology and SH2 domain-containing signaling protein, is a critical signaling protein for NGF. TrkA bound to glutathione S-transferase fusion proteins containing SH2-Bbeta, and NGF stimulation dramatically increased that binding. In contrast, NGF was unable to stimulate the association of TrkA with a glutathione S-transferase fusion protein containing a mutant SH2-Bbeta(R555E) with a defective SH2 domain. When overexpressed in PC12 cells, SH2-Bbeta co-immunoprecipitated with TrkA in response to NGF. NGF stimulated tyrosyl phosphorylation of endogenous SH2-Bbeta as well as exogenously expressed GFP-SH2-Bbeta but not GFP-SH2-Bbeta(R555E). Overexpression of SH2-Bbeta(R555E) blocked NGF-induced neurite outgrowth of PC12 cells, whereas overexpression of wild type SH2-Bbeta enhanced NGF-induced neurite outgrowth. Overexpression of either wild type or mutant SH2-Bbeta(R555E) did not alter tyrosyl phosphorylation of TrkA, Shc, or phospholipase Cgamma in response to NGF or NGF-induced activation of ERK1/2, suggesting that SH2-Bbeta may initiate a previously unknown pathway(s) that is essential for NGF-induced neurite outgrowth. Taken together, these data indicate that SH2-Bbeta is a novel signaling molecule required for NGF-induced neuronal differentiation.

A functional DNA binding domain is required for growth hormone-induced nuclear accumulation of Stat5B

The mechanisms regulating the cellular distribution of STAT family transcription factors remain poorly understood. To identify regions of Stat5B required for ligand-induced nuclear accumulation, we constructed a cDNA encoding green fluorescent protein (GFP) fused to the N terminus of Stat5B and performed site-directed mutagenesis. When co-expressed with growth hormone (GH) receptor in COS-7 cells, GFP-Stat5B is tyrosyl-phosphorylated, forms dimers, and binds DNA in response to GH in a manner indistinguishable from untagged Stat5B. In multiple cell types, laser scanning confocal imaging of GFP-Stat5B co-expressed with GH receptor shows that GFP-Stat5B undergoes a rapid, dramatic accumulation in the nucleus upon GH stimulation. We introduced alanine substitutions in several regions of Stat5B and assayed for GH-dependent nuclear localization. Only the mutation that prevented binding to DNA (466VVVI469) abrogated GH-stimulated nuclear localization. This mutant fusion protein is tyrosyl-phosphorylated and dimerizes in response to GH. These results suggest that either high affinity binding to DNA contributes to nuclear accumulation of Stat5B or that this region is crucial for two functions, namely accumulation of Stat5B in the nucleus and DNA binding. Thus, we have identified a mutant Stat5 defective in nuclear localization despite its ability to be tyrosyl-phosphorylated and to dimerize.

Platelet-derived growth factor (PDGF) stimulates the association of SH2-Bbeta with PDGF receptor and phosphorylation of SH2-Bbeta

We recently identified SH2-Bbeta as a JAK2-binding protein and substrate involved in the signaling of receptors for growth hormone and interferon-gamma. In this work, we report that SH2-Bbeta also functions as a signaling molecule for platelet-derived growth factor (PDGF). SH2-Bbeta fused to glutathione S-transferase (GST) bound PDGF receptor (PDGFR) from PDGF-treated but not control cells. GST fusion protein containing only the SH2 domain of SH2-Bbeta also bound PDGFR from PDGF-treated cells. An Arg to Glu mutation within the FLVRQS motif in the SH2 domain of SH2-Bbeta inhibited GST-SH2-Bbeta binding to tyrosyl-phosphorylated PDGFR. The N-terminal truncated SH2-Bbeta containing the entire SH2 domain interacted directly with tyrosyl-phosphorylated PDGFR from PDGF-treated cells but not unphosphorylated PDGFR from control cells in a Far Western assay. These results suggest that the SH2 domain of SH2-Bbeta is necessary and sufficient to mediate the interaction between SH2-Bbeta and PDGFR. PDGF stimulated coimmunoprecipitation of endogenous SH2-Bbeta with endogenous PDGFR in both 3T3-F442A and NIH3T3 cells. PDGF stimulated the rapid and transient phosphorylation of SH2-Bbeta on tyrosines and most likely on serines and/or threonines. Similarly, epidermal growth factor stimulated the phosphorylation of SH2-Bbeta; however, phosphorylation appears to be predominantly on serines and/or threonines. In response to PDGF, SH2-Bbeta associated with multiple tyrosyl-phosphorylated proteins, at least one of which (designated p84) does not bind to PDGFR. Taken together, these data strongly argue that, in response to PDGF, SH2-Bbeta directly interacts with PDGFR and is phosphorylated on tyrosine and most likely on serines and/or threonines, and acts as a signaling protein for PDGFR.