ROS-Mediated ABA Signaling

In plants, reactive oxygen species (ROS) are short-lived molecules produced through various cellular mechanisms in response to biotic and abiotic stimuli. ROS function as second messengers for hormone signaling, development, oxygen deprivation, programmed cell death, and plant–pathogen interactions. Recent research on ROS-mediated responses has produced stimulating findings such as the specific sources of ROS production, molecular elements that work in ROS-mediated signaling and homeostasis, and a ROS-regulated gene network (Neill et al., Curr Opin Plant Biol 5:388–395, 2002a; Apel and Hirt, Annu Rev Plant Biol 55:373–399, 2004; Mittler et al., Trends Plant Sci 9:490–498, 2004; Mori and Schroeder, Plant Physiol 135:702–708, 2004; Kwak et al., Plant Physiol 141:323–329, 2006; Torres et al., Plant Physiol 141:373–378, 2006; Miller et al., Physiol Plant 133:481–489, 2008). In this review, we highlight new discoveries in ROS-mediated abscisic acid (ABA) signaling. Drs. Daeshik Cho and June M. Kwak are the corresponding authors for this paper.     

2,4-Diaminopyrimidine MK2 inhibitors. Part II: Structure-based inhibitor optimization

We describe structure-based optimization of a series of novel 2,4-diaminopyrimidine MK2 inhibitors. Co-crystal structures (see accompanying Letter) demonstrated a unique inhibitor binding mode. Resulting inhibitors had IC₅₀ values as low as 19 nM and moderate selectivity against a kinase panel. Compounds 15, 31a, and 31b inhibit TNFα production in peripheral human monocytes.     

Physiological changes and growth promotion induced in poplar seedlings by the plant growth-promoting rhizobacteria Bacillus subtilis JS

Photosynthetica - This study aimed to determine the effects of plant growth-promoting rhizobacteria Bacillus subtilis JS on the growth and physiological changes of Populus euramericana and Populus...     

Survey on the impact of comorbid allergic rhinitis in patients with asthma

Background

Allergic rhinitis (AR) and asthma are inflammatory conditions of the airways that often occur concomitantly. This global survey was undertaken to understand patient perspectives regarding symptoms, treatments, and the impact on their well-being of comorbid AR and asthma.

Methods

Survey participants were adults with asthma (n = 813) and parents of children with asthma (n = 806) from four countries each in the Asia-Pacific region and Europe. Patients included in the survey also had self-reported, concomitant AR symptoms. Patients and parents were recruited by telephone interview or by direct interview.

Results

Most patients (73%) had pre-existing symptoms of AR when their asthma was first diagnosed. Shortness of breath (21%) was the most troublesome symptom for adults, and wheezing (17%) and coughing (17%) the most troublesome for children. Patients used different medications for treating asthma (most commonly short-acting β-agonists and inhaled corticosteroids) and for treating AR (most commonly oral antihistamines). The concomitant presence of AR and asthma disrupted the ability to get a good night's sleep (79%), to participate in leisure and sports activities (75%), to concentrate at work or school (69% of adults, 73% of children), and to enjoy social activities (57% of adults, 51% of children). Most patients (79%) reported worsening asthma symptoms when AR symptoms flared up. Many (56%) avoided the outdoors during the allergy season because of worsening asthma symptoms. Many (60%) indicated difficulty in effectively treating both conditions, and 72% were concerned about using excessive medication. In general, respondents from the Asia-Pacific region reported more disruption of activities caused by symptoms and more concerns and difficulties with medications than did those from Europe. Differences between the two regions in medication use included more common use of inhaled corticosteroids in Europe and more common use of Chinese herbal remedies in the Asia-Pacific region.

Conclusion

Results of this survey suggest that comorbid asthma and AR substantially impact patient well-being and that the worsening of AR symptoms in patients with asthma can be associated with worsening asthma symptoms. These findings underscore the need for physicians who treat patients with asthma to evaluate treatment options for improving symptoms of both AR and asthma when present concomitantly.

     

Silencing of MicroRNA-21 Confers Radio-Sensitivity through Inhibition of the PI3K/AKT Pathway and Enhancing Autophagy in Malignant Glioma Cell Lines

Radiation is a core part of therapy for malignant glioma and is often provided following debulking surgery. However, resistance to radiation occurs in most patients, and the underlying molecular mechanisms of radio-resistance are not fully understood. Here, we demonstrated that microRNA 21 (miR-21), a well-known onco-microRNA in malignant glioma, is one of the major players in radio-resistance. Radio-resistance in different malignant glioma cell lines measured by cytotoxic cell survival assay was closely associated with miR-21 expression level. Blocking miR-21 with anti-miR-21 resulted in radio-sensitization of U373 and U87 cells, whereas overexpression of miR-21 lead to a decrease in radio-sensitivity of LN18 and LN428 cells. Anti-miR-21 sustained γ-H2AX DNA foci formation, which is an indicator of double-strand DNA damage, up to 24 hours and suppressed phospho-Akt (ser473) expression after exposure to γ-irradiation. In a cell cycle analysis, a significant increase in the G₂/M phase transition by anti-miR-21 was observed at 48 hours after irradiation. Interestingly, our results showed that anti-miR-21 increased factors associated with autophagosome formation and autophagy activity, which was measured by acid vesicular organelles, LC3 protein expression, and the percentage of GFP-LC3 positive cells. Furthermore, augmented autophagy by anti-miR-21 resulted in an increase in the apoptotic population after irradiation. Our results show that miR-21 is a pivotal molecule for circumventing radiation-induced cell death in malignant glioma cells through the regulation of autophagy and provide a novel phenomenon for the acquisition of radio-resistance.     

Tissue-Protective Effects of NKG2A in Immune-Mediated Clearance of Virus Infection

Virus infection triggers a CD8⁺ T cell response that aids in virus clearance, but also expresses effector functions that may result in tissue injury. CD8⁺ T cells express a variety of activating and inhibiting ligands, though regulation of the expression of inhibitory receptors is not well understood. The ligand for the inhibitory receptor, NKG2A, is the non-classical MHC-I molecule Qa1^b, which may also serve as a putative restricting element for the T cell receptors of purported regulatory CD8⁺ T cells. We have previously shown that Qa1^b-null mice suffer considerably enhanced immunopathologic lung injury in the context of CD8⁺ T cell-mediated clearance of influenza infection, as well as evidence in a non-viral system that failure to ligate NKG2A on CD8⁺ effector T cells may represent an important component of this process. In this report, we examine the requirements for induction of NKG2A expression, and show that NKG2A expression by CD8⁺ T cells occurs as a result of migration from the MLN to the inflammatory lung environment, irrespective of peripheral antigen recognition. Further, we confirmed that NKG2A is a mediator in limiting immunopathology in virus infection using mice with a targeted deletion of NKG2A, and infecting the mutants with two different viruses, influenza and adenovirus. In neither infection is virus clearance altered. In influenza infection, the enhanced lung injury was associated with increased chemoattractant production, increased infiltration of inflammatory cells, and significantly enhanced alveolar hemorrhage. The primary mechanism of enhanced injury was the loss of negative regulation of CD8⁺ T cell effector function. A similar effect was observed in the livers of mutant mice infected intravenously with adenovirus. These results demonstrate the immunoregulatory role of CD8⁺ NKG2A expression in virus infection, which negatively regulates T cell effector functions and contributes to protection of tissue integrity during virus clearance.     

SOBIR1 requires the GxxxG dimerization motif in its transmembrane domain to form constitutive complexes with receptor‐like proteins

Receptor‐like proteins (RLPs), forming an important group of transmembrane receptors in plants, play roles in development and immunity. RLPs contain extracellular leucine‐rich repeats (LRRs) and, in contrast with receptor‐like kinases (RLKs), lack a cytoplasmic kinase required for the initiation of downstream signalling. Recent studies have revealed that the RLK SOBIR1/EVR (SUPPRESSOR OF BIR1‐1/EVERSHED) specifically interacts with RLPs. SOBIR1 stabilizes RLPs and is required for their function. However, the mechanism by which SOBIR1 associates with RLPs and regulates RLP function remains unknown. The Cf immune receptors of tomato (Solanum lycopersicum), mediating resistance to the fungus Cladosporium fulvum, are RLPs that also interact with SOBIR1. Here, we show that both the LRR and kinase domain of SOBIR1 are dispensable for association with the RLP Cf‐4, whereas the highly conserved GxxxGxxxG motif present in the transmembrane domain of SOBIR1 is essential for its interaction with Cf‐4 and additional RLPs. Complementation assays in Nicotiana benthamiana, in which endogenous SOBIR1 levels were knocked down by virus‐induced gene silencing, showed that the LRR domain as well as the kinase activity of SOBIR1 are required for the Cf‐4/Avr4‐triggered hypersensitive response (HR). In contrast, the LRRs and kinase activity of SOBIR1 are not required for facilitation of Cf‐4 accumulation. Together, these results suggest that, in addition to being a stabilizing scaffold for RLPs, SOBIR1 is also required for the initiation of downstream signalling through its kinase domain.     

Overexpression of a new rice vacuolar antiporter regulating protein OsARP improves salt tolerance in tobacco

We examined the function of the rice (Oryza sativa L.) antiporter-regulating protein OsARP by overexpressing it in tobacco (Nicotiana tabacum L.). In public databases, this protein was annotated as a putative Os02g0465900 protein of rice. The OsARP gene was introduced into tobacco under the control of the cauliflower mosaic virus 35S promoter. The transformants were selected for their ability to grow on medium containing kanamycin. Incorporation of the transgene in the genome of tobacco was confirmed by PCR, and its expression was confirmed by Western blot analysis. Transgenic plants had better growth and vigor than non-transgenic plants under salt stress in vitro. Overexpression of OsARP in transgenic tobacco plants resulted in salt tolerance, and the plants had a higher rate of photosynthesis and effective PSII photon yield when compared with the wild type. The OsARP protein was localized in the tonoplast of rice plants. Transgenic plants accumulated more Na+ in their leaf tissue than did wild-type plants. It is conceivable that the toxic effect of Na+ in the cytosol might be reduced by sequestration into vacuoles. The rate of water loss was higher in the wild type than in transgenic plants under salt stress. Increased vacuolar solute accumulation and water retention could confer salt tolerance in transgenic plants. Tonoplast vesicles isolated from OsARP transgenic plants showed Na+/H+ exchange rates 3-fold higher than those of wild-type plants. These results suggest that OsARP on the tonoplasts plays an important role in compartmentation of Na+ into vacuoles. We suggest that OsARP is a new type of protein participating in Na+ uptake in vacuoles.     

Identification of toxicological biomarkers of di(2‐ethylhexyl) phthalate in proteins secreted by HepG2 cells using proteomic analysis

The effects of di(2‐ethylhexyl) phthalate (DEHP) on proteins secreted by HepG2 cells were studied using a proteomic approach. HepG2 cells were exposed to various concentrations of DEHP (0, 2.5, 5, 10, 25, 50, 100, and 250 μM) for 24 or 48 h. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) and comet assays were then conducted to determine the cytotoxicity and genotoxicity of DEHP, respectively. The MTT assay showed that 10 μM DEHP was the maximum concentration that did not cause cell death. In addition, the DNA damage in HepG2 cells exposed to DEHP was found to increase in a dose‐ and time‐dependent fashion. Proteomic analysis using two different pI ranges (4–7 and 6–9) and large size 2‐DE revealed the presence of 2776 protein spots. A total of 35 (19 up‐ and 16 down‐regulated) proteins were identified as biomarkers of DEHP by ESI‐MS/MS. Several differentiated protein groups were also found. Proteins involved in apoptosis, transportation, signaling, energy metabolism, and cell structure and motility were found to be up‐ or down‐regulated. Among these, the identities of cystatin C, Rho GDP inhibitor, retinol binding protein 4, gelsolin, DEK protein, Raf kinase inhibitory protein, triose phosphate isomerase, cofilin‐1, and haptoglobin‐related protein were confirmed by Western blot assay. Therefore, these proteins could be used as potential biomarkers of DEHP and human disease associated with DEHP.