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author:("Zhang, yanji")
1.  A Non-Climacteric Fruit Gene CaMADS-RIN Regulates Fruit Ripening and Ethylene Biosynthesis in Climacteric Fruit 
PLoS ONE  2014;9(4):e95559.
MADS-box genes have been reported to play a major role in the molecular circuit of developmental regulation. Especially, SEPALLATA (SEP) group genes play a central role in the developmental regulation of ripening in both climacteric and non-climacteric fruits. However, the mechanisms underlying the regulation of SEP genes to non-climacteric fruits ripening are still unclear. Here a SEP gene of pepper, CaMADS-RIN, has been cloned and exhibited elevated expression at the onset of ripening of pepper. To further explore the function of CaMADS-RIN, an overexpressed construct was created and transformed into ripening inhibitor (rin) mutant tomato plants. Broad ripening phenotypes were observed in CaMADS-RIN overexpressed rin fruits. The accumulation of carotenoid and expression of PDS and ZDS were enhanced in overexpressed fruits compared with rin mutant. The transcripts of cell wall metabolism genes (PG, EXP1 and TBG4) and lipoxygenase genes (TomloxB and TomloxC) accumulated more abundant compared to rin mutant. Besides, both ethylene-dependent genes including ACS2, ACO1, E4 and E8 and ethylene-independent genes such as HDC and Nor were also up-regulated in transgenic fruits at different levels. Moreover, transgenic fruits showed approximately 1–3 times increase in ethylene production compared with rin mutant fruits. Yeast two-hybrid screen results indicated that CaMADS-RIN could interact with TAGL1, FUL1 and itself respectively as SlMADS-RIN did in vitro. These results suggest that CaMADS-RIN affects fruit ripening of tomato both in ethylene-dependent and ethylene-independent aspects, which will provide a set of significant data to explore the role of SEP genes in ripening of non-climacteric fruits.
PMCID: PMC3994064  PMID: 24751940
2.  All-trans retinoic acid attenuates airway inflammation by inhibiting Th2 and Th17 response in experimental allergic asthma 
BMC Immunology  2013;14:28.
Airway inflammation is mainly mediated by T helper 2 cells (Th2) that characteristically produce interleukin (IL)-4, IL-5, and IL-13. Epidemiological studies have revealed an inverse association between the dietary intake of vitamin A and the occurrence of asthma. Serum vitamin A concentrations are significantly lower in asthmatic subjects than in healthy control subjects. It has been reported that all-trans retinoic acid (ATRA), a potent derivative of vitamin A, regulates immune responses. However, its role in Th2-mediated airway inflammation remains unclear. We investigated the effects of ATRA in a mouse model of allergic airway inflammation.
We found that ATRA treatment attenuated airway inflammation and decreased mRNA levels of Th2- and Th17-related transcription factors. The data showed that airway inflammation coincided with levels of Th2- and Th17-related cytokines. We also showed that ATRA inhibited Th17 and promoted inducible regulatory T-cell differentiation, whereas it did not induce an obvious effect on Th2 differentiation in vitro. Our data suggest that ATRA may interfere with the in vivo Th2 responses via T-cell extrinsic mechanisms.
Administration of ATRA dramatically attenuated airway inflammation by inhibiting Th2 and Th17 differentiation and/or functions. ATRA may have potential therapeutic effects for airway inflammation in asthmatic patients.
PMCID: PMC3695807  PMID: 23800145
Asthma; All-trans retinoic acid; Th2; Th17; Regulatory T cells
3.  mTOR-independent 4E-BP1 phosphorylation is associated with cancer resistance to mTOR kinase inhibitors 
Cell Cycle  2012;11(3):594-603.
ATP-competitive mTOR kinase inhibitors (mTorKIs) are a new generation of mTOR-targeted agents with more potent anticancer activity than rapamycin in several tumor models. However, the sensitivity and resistance of cancer cells to mTorKIs remain poorly understood. In this study, we tested mTorKIs against a large panel of colorectal cancer (CRC) cell lines, and found that mTorKIs displayed broader anti-CRC activity than rapamycin, including CRC cells with K-Ras or B-Raf mutations, suggesting that these mTorKIs are particularly useful for CRCs resistant to EGFR inhibitors. Unexpectedly, we found that 40% CRC cell lines were intrinsically drug resistant. Moreover, we discovered an mTOR-independent 4E-BP1 phosphorylation that was correlated with mTorKI resistance. Altogether, our findings provide compelling preclinical support for testing mTorKIs in human CRC clinical trials. They further reveal the existence of significant intrinsic mTorKI drug resistance in cancer cells and suggest that 4E-BP1 phosphorylation is a predictive biomarker for mTorKI sensitivity and resistance.
PMCID: PMC3315097  PMID: 22262166
mTOR; kinase; colorectal cancer; drug resistance; 4E-BP1; phosphorylation
4.  Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides 
The journal of physical chemistry. B  2008;112(44):13765-13771.
The modulation of the lower critical solution temperature (LCST) of two elastin-like polypeptides (ELPs) was investigated in the presence of 11 sodium salts that span the Hofmeister series for anions. It was found that the hydrophobic collapse/aggregation of these ELPs generally followed the series. Specifically, kosmotropic anions decreased the LCST by polarizing interfacial water molecules involved in hydrating amide groups on the ELPs. On the other hand, chaotropic anions lowered the LCST through a surface tension effect. Additionally, chaotropic anions showed salting-in properties at low salt concentrations that were related to the saturation binding of anions with the biopolymers. These overall mechanistic effects were similar to those previously found for the hydrophobic collapse and aggregation of poly(N-isopropylacrylamide), PNIPAM. There is, however, a crucial difference between PNIPAM and ELPs. Namely, PNIPAM undergoes a two-step collapse process as a function of temperature in the presence of sufficient concentrations of kosmotropic salts. By contrast, ELPs undergo collapse in a single step in all cases studied herein. This suggests that the removal of water molecules from around the amide moieties triggers the removal of hydrophobic hydration waters in a highly coupled process. There are also some key differences between the LCST behavior of the two ELPs. Specifically, the more hydrophilic ELP V5A2G3-120 construct displays collapse/aggregation behavior that is consistent with a higher concentration of anions partitioning to polymer/aqueous interface as compared to the more hydrophobic ELP V5-120. It was also found that larger anions could bind with ELP V5A2G3-120 more readily in comparison with ELP V5-120. These latter results were interpreted in terms of relative binding site accessibility of the anion for the ELP.
PMCID: PMC3475179  PMID: 18842018
5.  GM1 Clustering Inhibits Cholera Toxin Binding in Supported Phospholipid Membranes 
The present studies explore multivalent ligand–receptor interactions between pentameric cholera toxin B subunits (CTB) and the corresponding membrane ligand, ganglioside GM1. CTB binding was monitored on supported phospholipid bilayers coated on the walls and floors of microfluidic channels. Measurements were made by total internal reflection fluorescence microscopy (TIRFM). Apparent dissociation constants were extracted by fitting the binding data to both the Hill–Waud and Langmuir adsorption isotherm equations. Studies of the effect of ligand density on multivalent CTB–GM1 interactions revealed that binding weakened with increasing GM1 density from 0.02 mol % to 10.0 mol %. Such a result could be explained by the clustering of GM1 on the supported phospholipid membranes, which in turn inhibited the binding of CTB. Atomic force microscopy (AFM) experiments directly verified GM1 clustering within the supported POPC bilayers.
PMCID: PMC3475181  PMID: 17429973
6.  Synthesized OVA323-339MAP octamers mitigate OVA-induced airway inflammation by regulating Foxp3 T regulatory cells 
BMC Immunology  2012;13:34.
Antigen-specific immunotherapy (SIT) has been widely practiced in treating allergic diseases such as asthma. However, this therapy may induce a series of allergic adverse events during treatment. Peptide immunotherapy (PIT) was explored to overcome these disadvantages. We confirmed that multiple antigen peptides (MAPs) do not cause autoimmune responses, which led to the presumption that MAPs intervention could alleviate allergic airway inflammation without inducing adverse effects.
In this study, synthesized OVA323-339MAP octamers were subcutaneously injected into ovalbumin (OVA)-sensitized and -challenged Balb/c mice to observe its effect on allergic airway inflammation, Th2 immune response, and immune regulating function. It was confirmed that OVA sensitization and challenge led to significant peritracheal inflammatory, cell infiltration, and intensive Th2 response. Treatment of OVA323-339MAP octomers in the airway inflammation mice model increased CD4+CD25+Foxp3+ T regulatory (Treg) cells and their regulatory function in peripheral blood, mediastinal draining lymph nodes, and the spleen. Furthermore, OVA323-339MAP increased IL-10 levels in bronchial alveolar lavage fluid (BALF); up-regulated the expression of IL-10, membrane-bound TGF-β1, as well as Foxp3 in lung tissues; and up-regulated programmed death-1 (PD-1) and cytotoxic T lymphocyte associated antigen 4 (CTLA-4) on the surface of Treg cells. These results were further correlated with the decreased OVA specific immunoglobulin E (sIgE) level and the infiltration of inflammatory cells such as eosinophils and lymphocytes in BALF. However, OVA323-339 peptide monomers did not show any of the mentioned effects in the same animal model.
Our study indicates that OVA323-339MAP had significant therapeutic effects on mice allergic airway inflammation by regulating the balance of Th1/Th2 response through Treg cells in vivo.
PMCID: PMC3472185  PMID: 22769043
Allergic airway inflammation; Specific immunotherapy; Multiple antigen peptide
7.  Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals 
Sensors (Basel, Switzerland)  2011;11(12):11036-11055.
Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands.
PMCID: PMC3251968  PMID: 22247651
quantum dots; ligand; biocompatible
8.  Hydrogen Bonding of β-Turn Structure Is Stabilized in D2O 
Journal of the American Chemical Society  2009;131(42):15188-15193.
The lower critical solution temperature (LCST) of elastin-like polypeptides (ELPs) was investigated as a function of ELP chain length and guest residue chemistry. These measurements were made in both D2O and H2O. Differences in the LCST values with heavy and light water were correlated with secondary structure formation of the polypeptide chains. Such structural information was obtained by circular dichroism and infrared measurements. Additional thermodynamic data were obtained by differential scanning calorimetry. It was found that there is a greater change in the LCST value between H2O and D2O for those polypeptides which form the greatest amount of β-turn/β-aggregate structure. Moreover, these same molecules were the least hydrophobic ELPs. Therefore, hydrogen bonding rather than hydrophobicity was the key factor in the stabilization of the collapsed state of ELPs in D2O compared with H2O.
PMCID: PMC3003597  PMID: 19919159
9.  Comprehensive Brain MRI Segmentation in High Risk Preterm Newborns 
PLoS ONE  2010;5(11):e13874.
Most extremely preterm newborns exhibit cerebral atrophy/growth disturbances and white matter signal abnormalities on MRI at term-equivalent age. MRI brain volumes could serve as biomarkers for evaluating the effects of neonatal intensive care and predicting neurodevelopmental outcomes. This requires detailed, accurate, and reliable brain MRI segmentation methods. We describe our efforts to develop such methods in high risk newborns using a combination of manual and automated segmentation tools. After intensive efforts to accurately define structural boundaries, two trained raters independently performed manual segmentation of nine subcortical structures using axial T2-weighted MRI scans from 20 randomly selected extremely preterm infants. All scans were re-segmented by both raters to assess reliability. High intra-rater reliability was achieved, as assessed by repeatability and intra-class correlation coefficients (ICC range: 0.97 to 0.99) for all manually segmented regions. Inter-rater reliability was slightly lower (ICC range: 0.93 to 0.99). A semi-automated segmentation approach was developed that combined the parametric strengths of the Hidden Markov Random Field Expectation Maximization algorithm with non-parametric Parzen window classifier resulting in accurate white matter, gray matter, and CSF segmentation. Final manual correction of misclassification errors improved accuracy (similarity index range: 0.87 to 0.89) and facilitated objective quantification of white matter signal abnormalities. The semi-automated and manual methods were seamlessly integrated to generate full brain segmentation within two hours. This comprehensive approach can facilitate the evaluation of large cohorts to rigorously evaluate the utility of regional brain volumes as biomarkers of neonatal care and surrogate endpoints for neurodevelopmental outcomes.
PMCID: PMC2975631  PMID: 21079730
10.  Effects of Hofmeister Anions on the LCST of PNIPAM as a Function of Molecular Weight 
The effect of a series of sodium salts on the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide), PNIPAM, was investigated as a function of molecular weight and polymer concentration with a temperature gradient microfluidic device under a dark-field microscope. In solutions containing sufficient concentrations of kosmotropic anions, the phase transition of PNIPAM was resolved into two separate steps for higher molecular weight samples. The first step of this two step transition was found to be sensitive to the polymer’s molecular weight and solution concentration, while the second step was not. Moreover, the binding of chaotropic anions to the polymer was also influenced by molecular weight. Both sets of results could be explained by the formation of intramolecular and intermolecular hydrogen-bonding between polymer chains. By contrast, the hydrophobic hydration of the isopropyl moieties and polymer backbone was found to be unaffected by either the polymer’s molecular weight or solution concentration.
PMCID: PMC2553222  PMID: 18820735

Results 1-10 (10)