Insulin receptor substrate 1-induced inhibition of endoplasmic reticulum Ca2+ uptake in beta-cells. Autocrine regulation of intracellular ca2+ homeostasis and insulin secretion.

To understand the role of the insulin receptor pathway in beta-cell function, we have generated stable beta-cells (betaIRS1-A) that overexpress by 2-fold the insulin receptor substrate-1 (IRS-1) and compared them to vector-expressing controls. IRS-1 overexpression dramatically increased basal cytosolic Ca2+ levels from 81 to 278 nM, but it did not affect Ca2+ response to glucose. Overexpression of the insulin receptor also caused an increase in cytosolic Ca2+. Increased cytosolic Ca2+ was due to inhibition of Ca2+ uptake by the endoplasmic reticulum, because endoplasmic reticulum Ca2+ uptake and content were reduced in betaIRS1-A cells. Fractional insulin secretion was significantly increased 2-fold, and there was a decrease in betaIRS1-A insulin content and insulin biosynthesis. Steady-state insulin mRNA levels and glucose-stimulated ATP were unchanged. High IRS-1 levels also reduced beta-cell proliferation. These data demonstrate a direct link between the insulin receptor signaling pathway and the Ca2+-dependent pathways regulating insulin secretion of beta-cells. We postulate that during regulated insulin secretion, released insulin binds the beta-cell insulin receptor and activates IRS-1, thus further increasing cytosolic Ca2+ by reducing Ca2+ uptake. We suggest the existence of a novel pathway of autocrine regulation of intracellular Ca2+ homeostasis and insulin secretion in the beta-cell of the endocrine pancreas.     

Variants of endothelin-1 and its receptors in atopic asthma.

Endothelin-1 (ET-1) is a 21 amino acid peptide released from several types of bronchial cells. It operates through two types of receptors, type A(ET-RA) and type B(ET-RB) and has various activities in the pathophysiology of atopic asthma. These genes are localised on different chromosomes where genome-wide searches have identified linkage for atopic asthma, thus supporting the candidacy of ET-1 and its receptors for atopic asthma. A genetic association study was performed with variants of these three genes in both British (n = 300) and Japanese populations (n = 200). No significant association was found between variants of EDN1 and EDNRB genes, and atopic asthma in either population. However, variants of EDNRA gene showed a marginal association with atopy [odds = 0.39(95% CI: 0.17-0.89), p = 0.022, Pc = 0.066], especially with antigen specific IgE levels [odds = 0.31 (95% CI: 0.20-0.77), p = 0.006, Pc = 0.018] in the British population. These findings suggest that EDNRA is a major candidate locus for atopy on chromosome 4.     

Production of a thermostable metal-tolerant laccase from Trametes versicolor and its application in dye decolorization

Production of laccase using a submerged culture of Trametes versicolor sdu-4 was optimized using a central composite design of the Response Surface Methodology. Optimized conditions gave a laccase yield of 4,213 U/L which was approximately three times of that in basal medium. The laccase was purified to homogeneity using a three-step process. The overall yield of the purification was 58%, with a purification fold of 11.4 and a specific activity of 1320.7 U/mg protein. The molecular mass of the laccase was 60 kDa. The optimum pH values of the enzyme were 2.2, 3.7, and 7 for the oxidations of ABTS, DMP, and syringaldazine, respectively. The enzyme had adaptability to a broad pH range and high temperature and wsa stable at pH 3.0 ∼ 10.0. The half-life of this laccase at 70°C was 2.2 h. Methyl red, 2-bromophenol, and 4-bromophenol were oxidized by the purified laccase in the absence of mediators. Purified laccase was effective in the decolorization of several dyes and was not inhibited by Cu²⁺, Mn²⁺, Zn²⁺, Na⁺, K⁺, Mg²⁺, Ba²⁺, and Ca²⁺ at 5 mM. These excellent characteristics made it a highly attractive candidate for industrial use.     

PHB3 Maintains Root Stem Cell Niche Identity through ROS-Responsive AP2/ERF Transcription Factors in Arabidopsis

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Mapping and validation of a new QTL for adult-plant resistance to powdery mildew in Chinese elite bread wheat line Zhou8425B

Key message

Four QTLs for adult-plant resistance to powdery mildew were mapped in the Zhou8425B/Chinese Spring population, and a new QTL on chromosome 3B was validated in 103 wheat cultivars derived from Zhou8425B.

Abstract

Zhou8425B is an elite wheat (Triticum aestivum L.) line widely used as a parent in Chinese wheat breeding programs. Identification of genes for adult-plant resistance (APR) to powdery mildew in Zhou8425B is of high importance for continued controlling the disease. In the current study, the high-density Illumina iSelect 90K single-nucleotide polymorphism (SNP) array was used to map quantitative trait loci (QTL) for APR to powdery mildew in 244 recombinant inbred lines derived from the cross Zhou8425B/Chinese Spring. Inclusive composite interval mapping identified QTL on chromosomes 1B, 3B, 4B, and 7D, designated as QPm.caas-1BL.1, QPm.caas-3BS, QPm.caas-4BL.2, and QPm.caas-7DS, respectively. Resistance alleles at the QPm.caas-1BL.1, QPm.caas-3BS, and QPm.caas-4BL.2 loci were contributed by Zhou8425B, whereas that at QPm.caas-7DS was from Chinese Spring. QPm.caas-3BS, likely to be a new APR gene for powdery mildew resistance, was detected in all four environments. One SNP marker closely linked to QPm.caas-3BS was transferred into a semi-thermal asymmetric reverse PCR (STARP) marker and tested on 103 commercial wheat cultivars derived from Zhou8425B. Cultivars with the resistance allele at the QPm.caas-3BS locus had averaged maximum disease severity reduced by 5.3%. This STARP marker can be used for marker-assisted selection in improvement of the level of powdery mildew resistance in wheat breeding.

     

Lipopolysaccharide enhances TGF‐β1 signalling pathway and rat pancreatic fibrosis

Pancreatic stellate cells (PSCs) play a critical role in fibrogenesis during alcoholic chronic pancreatitis (ACP). Transforming growth factor‐beta1 (TGF‐β1) is a key regulator of extracellular matrix production and PSC activation. Endotoxin lipopolysaccharide (LPS) has been recognized as a trigger factor in the pathogenesis of ACP. This study aimed to investigate the mechanisms by which LPS modulates TGF‐β1 signalling and pancreatic fibrosis. Sprague‐Dawley rats fed with a Lieber‐DeCarli alcohol (ALC) liquid diet for 10 weeks with or without LPS challenge during the last 3 weeks. In vitro studies were performed using rat macrophages (Mφs) and PSCs (RP‐2 cell line). The results showed that repeated LPS challenge resulted in significantly more collagen production and PSC activation compared to rats fed with ALC alone. LPS administration caused overexpression of pancreatic TLR4 or TGF‐β1 which was paralleled by an increased number of TLR4‐positive or TGF‐β1‐positive Mφs or PSCs in ALC‐fed rats. In vitro, TLR4 or TGF‐β1 production in Mφs or RP‐2 cells was up‐regulated by LPS. LPS alone or in combination with TGF‐β1 significantly increased type I collagen and α‐SMA production and Smad2 and 3 phosphorylation in serum‐starved RP‐2 cells. TGF‐β pseudoreceptor BAMBI production was repressed by LPS, which was antagonized by Si‐TLR4 RNA or by inhibitors of MyD88/NF‐kB. Additionally, knockdown of Bambi with Si‐Bambi RNA significantly increased TGF‐β1 signalling in RP‐2 cells. These findings indicate that LPS increases TGF‐β1 production through paracrine and autocrine mechanisms and that LPS enhances TGF‐β1 signalling in PSCs by repressing BAMBI via TLR4/MyD88/NF‐kB activation.     

光学分子影像技术及其在药物研发领域的应用

光学分子影像技术是一种发展迅速的生物医学影像技术,能够利用生物发光技术或荧光蛋白等,对生物体内特定的生物过程进行无创的定性或定量研究。应用该技术可以对药物进行筛选,选取具有潜在治疗效果的药物进行后续研究,而终止对可能无效药物的研究,同时可以评价药物对肿瘤的代谢、增殖、血管形成、凋亡和组织乏氧等方面的影响。本文主要介绍光学分子影像技术及其在药物研发,尤其是抗肿瘤药物研发领域的应用。     

Alisol A attenuates high‐fat‐diet‐induced obesity and metabolic disorders via the AMPK/ACC/SREBP‐1c pathway

Obesity and its associated metabolic disorders such as diabetes, hepatic steatosis and chronic heart diseases are affecting billions of individuals. However there is no satisfactory drug to treat such diseases. In this study, we found that alisol A, a major active triterpene isolated from the Chinese traditional medicine Rhizoma Alismatis, could significantly attenuate high‐fat‐diet‐induced obesity. Our biochemical detection demonstrated that alisol A remarkably decreased lipid levels, alleviated glucose metabolism disorders and insulin resistance in high‐fat‐diet‐induced obese mice. We also found that alisol A reduced hepatic steatosis and improved liver function in the obese mice model.In addition, protein expression investigation revealed that alisol A had an active effect on AMPK/ACC/SREBP‐1c pathway. As suggested by the molecular docking study, such bioactivity of alisol A may result from its selective binding to the catalytic region of AMPK.Therefore, we believe that Alisol A could serve as a promising agent for treatment of obesity and its related metabolic diseases.     

The bracts of the alpine ‘glasshouse’ plant Rheum alexandrae (Polygonaceae) enhance reproductive fitness of its pollinating seed‐consuming mutualist

Environmental conditions are known to affect the reproductive fitness of insects, as do host plants. Although the highly specialized bracts of Himalayan ‘glasshouse’ plants are thought to be an adaptive morphology that allows the plant to reproduce in harsh alpine environments, little information appears to exist concerning the benefit of these bracts for the pollinating insects. In this study, we examine whether the semi‐translucent bracts of Rheum alexandrae, a giant herb endemic to the alpine zone of the Hengduan Mountains in south‐western China, enhance the reproductive fitness of its pollinator. Rheum alexandrae depends mainly on mutualistic seed‐consuming Bradysia flies for pollination. Bracts increased interior temperature on sunny days, acted as a buffer against fluctuating air humidity, greatly decreased the intensities of ultraviolet B/C radiation and provided shelter from strong winds. Bract removal significantly decreased adult oviposition and offspring performance of pollinators during flowering and fruiting, respectively. Our results indicate that the bracts of R. alexandrae enhance the reproductive fitness of its pollinating seed‐consuming mutualist in alpine environments, which may be attributed to the positive effects of the bracts on the interior microenvironment. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 349–359.