Auxin-responsive grape Aux/IAA9 regulates transgenic Arabidopsis plant growth.

We report the characterization of VvIAA9, an auxin/indole-3-acetic acid (Aux/IAA) protein, in grapevine (Vitis vinifera L.). VvIAA9 was expressed abundantly in leaves and berries. VvIAA9 transcription was drastically upregulated from anthesis to onset of ripening (termed véraison), in which berry diameter rapidly increased. Treatment with exogenous IAA induced VvIAA9 expression in grape leaves, suggesting that VvIAA9 is an auxin-responsive Aux/IAA protein. The overexpression of VvIAA9 in Arabidopsis thaliana promoted plant growth, including rapid floral transition. However, no morphological differences were observed between the control plant and the VvIAA9-overexpressing plant. The overexpression of VvIAA9 in Arabidopsis plants rendered the plants hyposensitive to exogenous IAA. The exogenous IAA treatment did not induce VvIAA9-overexpressing Arabidopsis plant growth and expression of IAA-responsive HAT2. Taken together, we conclude that grape Aux/IAA9 protein is likely to play a crucial role as a plant growth regulator.

Characterization of grape C-repeat-binding factor 2 and B-box-type zinc finger protein in transgenic Arabidopsis plants under stress conditions.

Simultaneous induction of multiple stress tolerance by single-gene transfer is a powerful strategy to engineer crop plants to improve tolerance to environmental stress under field condition. The possibility of enhancement of multiple stress tolerance by four grape transcription factors that enhance low-temperature tolerance (VvCBF2, VvCBF4, VvCBFL, and VvZFPL) were analyzed using the Arabidopsis plants overexpressing these factors. Consequently, two of the four proteins, VvCBF2 and VvZFPL, were found to confer tolerance to cold, drought, and salinity stresses in Arabidopsis plants, but not to heat stress. Photosynthesis-related genes were down-regulated in both CBF2- and ZFPL-overexpressing plants, resulting in plant growth retardation. On the other hand, the overexpression of VvCBF2 activated the transcription of CBL-interacting protein kinase 7, a serine/threonine kinase involved in cold response, in Arabidopsis plants. Our study provides that one of grape CBF family, VvCBF2, and one of B-box ZFP family, VvZFPL, confer multiple stress tolerance to plants.

Auxin-nonresponsive grape Aux/IAA19 is a positive regulator of plant growth.

We report the characterization of VvIAA19, an auxin/indole-3-acetic acid (Aux/IAA) protein, in grapevine (Vitis vinifera L.). VvIAA19 was expressed abundantly in berries. VvIAA19 transcription was rapidly increased at pre-anthesis and then decreased during fruit set. Before véraison, however, VvIAA19 gene expression was upregulated again and maximum expression was maintained until the end of ripening. Exogenous IAA did not induce VvIAA19 expression in grape leaves, suggesting that VvIAA19 might be auxin-nonresponsive. The overexpression of VvIAA19 in Arabidopsis thaliana had a notable effect on plant growth. Although no morphological changes were observed, transgenic Arabidopsis plants overexpressing VvIAA19 exhibited faster growth, including root elongation and floral transition, than the control plant, suggesting that the constitutive expression of VvIAA19 protein resulted in increased growth rates without any detectable harm. Taken together, we conclude that grape Aux/IAA19 protein is likely to play a crucial role as a plant growth regulator.

The enhancing effect of the antioxidant N-acetylcysteine on urinary bladder injury induced by dimethylarsinic acid.

Dimethylarsinic acid (DMA(V)), the major excreted metabolite of inorganic arsenic, is carcinogenic to the rat urinary bladder. Oxidative stress has been proposed as one possible mechanism of DMA(V)-induced carcinogenesis. The authors determined whether the antioxidant N-acetylcysteine (NAC) modifies DMA(V)-induced urinary bladder injury in rats. The treatment solutions--DMA(V) at 10 mg/kg, NAC at 90 or 1.6 mg/kg (high or low dose, respectively), and their combination--were intravesically instilled into female F344 rats over two hours under pentobarbital anesthesia. The treatment was conducted twice with an interval of three days. All animals were euthanized one day after the second treatment. NAC (low dose) alone did not induce histopathological changes or increase 5-bromo-2'-deoxyuridine (BrdU) labeling index in urothelial cells. Both DMA(V) and NAC (high dose) induced a weak neutrophil infiltration and an increase in the BrdU labeling index; these pathological changes were enhanced by the combined treatment of DMA(V) and NAC (high or low dose). Increased oxidative stress and urothelial cell hyperplasia with evidence of activated p44/42 MAPK (ERK1/2) and cyclin D1 were found in the DMA(V) and NAC (high dose) cotreated group. These results suggest that cotreatment with NAC enhanced DMA(V)-induced urinary bladder injury and that the effects may be mediated by excess oxidative stress and ERK signaling.

Altered pulmonary defense system in lung injury induced by didecyldimethylammonium chloride in mice.

Didecyldimethylammonium chloride (DDAC), a representative dialkyl-quaternary ammonium compound (QAC), could contaminate working atmospheres when used in disinfectant operation and adversely affect human health. Furthermore, the development of bacteria resistant to DDAC might become public health concern. We postulated that DDAC instillation in the lungs alters pulmonary antioxidant and antimicrobial responses and increases susceptibility to systemic administration of a bacterial component lipopolysaccharide (LPS). Mice were intratracheally instilled with DDAC and sacrificed 1, 3, or 7 days after treatment. Pulmonary cytotoxicity in recovered bronchoalveolar lavage was evident on Days 1 and 7, and inflammatory cell influx and interleukin-6 expression peaked on Day 7, in association with altered antioxidant and antimicrobial responses, as demonstrated by measuring heme oxygenase-1, glutathione peroxidase 2, lactoferrin, and mouse ß-defensin-2 and -3 mRNA in the lung samples. The impaired defense system tended to enhance the inflammatory reaction caused by a systemic administration of LPS; the effect was in association with increased expression of toll-like receptor-4 mRNA. The results suggest that DDAC alters pulmonary defense system, which may contribute to susceptibility to an exogenous infectious agent.

Didecyldimethylammonium chloride induces pulmonary fibrosis in association with TGF-ß signaling in mice.

Didecyldimethylammonium chloride (DDAC) is a representative dialkyl-quaternary ammonium compound that is used as a disinfectant against several pathogens and is also used in commercial, industrial, and residential settings. We previously investigated toxicity on air way system following single instillation of DDAC to the lungs in mice, and found that DDAC causes pulmonary injury, which is associated with altered antioxidant antimicrobial responses; the inflammatory phase is accompanied or followed by fibrotic response. The present study was conducted to monitor transforming growth factor-ß (TGF-ß) signaling in pulmonary fibrosis induced by DDAC. Mice were intratracheally instilled with DDAC and sacrificed 1, 3, or 7 days after treatment to measure TGF-ß signaling. In order to further evaluate TGF-ß signaling, we treated isolated mouse lung fibroblasts with DDAC. Fibrotic foci were observed in the lungs on day 3, and were widely extended on day 7, with evidence of increased α-smooth muscle actin-positive mesenchymal cells and upregulation of Type I procollagen mRNA. Developing fibrotic foci were likely associated with increased expression of Tgf-ß1 mRNA, in addition to decreased expression of Bone morphogenetic protein-7 mRNA. In fibrotic lung samples, the expression of phosphorylated SMAD2/3 was considerably higher than that of phosphorylated SMAD1/5. In isolated lung fibroblasts, the mRNA levels of Tgf-ß1 were specifically increased by DDAC treatment, which prolonged phosphorylation of SMAD2/3. These effects were abolished by treatment with SD208 - a TGF-ßRI kinase inhibitor. The results suggest that DDAC induces pulmonary fibrosis in association with TGF-ß signaling.

Pulmonary fibrosis in response to environmental cues and molecular targets involved in its pathogenesis.

Chronic lung injury resulting from a variety of different causes is frequently associated with the develop ment of pulmonary fibrosis in humans. Although the etiology of pulmonary fibrosis is generally unknown, several sources of evidence support the hypothesis that a number of environmental and occupational agents play an etiologic role in the pathogenesis of this disease. The agents discussed in this review include beryllium, nylon flock, textile printing aerosols, polyvinyl chloride and didecyldimethylammonium chloride. The authors also describe a variety of animal models, including genetically modified mice, in order to investigate the molecular mechanism of pulmonary fibrosis, focusing on chemokine receptors, regulatory T cells and transforming growth factor-ß and bone morphogenetic protein signaling. Overall, we propose the concept of toxicological pulmonary fibrosis as a lung disease induced in response to environmental cues.