No abstract

AIMP2/p38 is a scaffolding protein required for the assembly of the macromolecular tRNA synthetase complex. Here, we describe a previously unknown function for AIMP2 as a positive regulator of p53 in response to genotoxic stresses. Depletion of AIMP2 increased resistance to DNA damage-induced apoptosis, and introduction of AIMP2 into AIMP2-deficient cells restored the susceptibility to apoptosis. Upon DNA damage, AIMP2 was phosphorylated, dissociated from the multi-tRNA synthetase complex, and translocated into the nuclei of cells. AIMP2 directly interacts with p53, thereby preventing MDM2-mediated ubiquitination and degradation of p53. Mutations in AIMP2, affecting its interaction with p53, hampered its ability to activate p53. Nutlin-3 recovered the level of p53 and the susceptibility to UV-induced cell death in AIMP2-deficient cells. This work demonstrates that AIMP2, a component of the translational machinery, functions as proapoptotic factor via p53 in response to DNA damage.A minoacyl-tRNA synthetases (ARSs) are the enzymes that ligate specific amino acids to tRNAs before protein synthesis. In higher eukaryotic systems, nine different ARSs form an intriguing macromolecular complex with three nonenzymatic factors called ARS-interacting, multifunctional proteins (AIMPs) (1, 2). Many of these complex-forming ARSs, as well as AIMPs, play diverse regulatory roles that are not directly related to protein synthesis (2). Among the three AIMPs, AIMP1 is secreted as a cytokine working in immune, angiogenesis, and wound-healing processes (3-7) and also functions as a hormone controlling glucose homeostasis (8). AIMP3 is a tumor suppressor required for chromosome integrity (9, 10). Although AIMP2 is critical for the assembly of the multi-ARS complex (11), it also suppresses cell proliferation via down-regulation of c-Myc (12). In addition, AIMP2 was shown to be involved in Parkinson's disease, inducing neural cell death (13). However, it is yet to be determined how AIMP2 is involved in the control of cell death. In this work, we investigated the functional significance and molecular behavior of AIMP2 during the control of cell death and the relationship of AIMP2 associated with the multi-ARS complex and its proapoptotic activity. Results AIMP2-Deficient Cells AreResistant to Cell Death. To see the importance of AIMP2 during the control of cell death, we subjected 12.5-d AIMP2 ϩ/ϩ and AIMP2 Ϫ/Ϫ mouse embryonic fibroblasts (MEFs) to UV irradiation and compared their apoptotic sensitivity. The apoptotic cells, indicated by the subG1 portion, were increased Ϸ3-fold by UV irradiation in AIMP2 ϩ/ϩ but not in AIMP2 Ϫ/Ϫ cells (Fig. 1A). Transfection of AIMP2 into AIMP2 Ϫ/Ϫ MEFs restored the apoptotic sensitivity to UV irradiation (Fig. 1B). We also compared the apoptotic response of AIMP2 ϩ/ϩ and AIMP2 Ϫ/Ϫ MEFs to UV irradiation by monitoring caspase-3 activation. Procaspase-3 cleavage resulting in caspase-3 generation was observed in AIMP2 ϩ/ϩ but not in AIMP2 Ϫ/Ϫ cells (Fig. 1C). Suppression of AIMP2 via gene-specific siRNA...

Body Distribution of Inhaled FluorescentMagnetic Nanoparticles in the Mice: Jung-Taek KWON, et al. Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Korea-Reducing the particle size of materials is an efficient and reliable tool for improving the bioavailability of a gene or drug delivery system. In fact, nanotechnology helps in overcoming the limitations of size and can change the outlook of the world regarding science. However, a potential harmful effect of nanomaterial on workers manufacturing nanoparticles is expected in the workplace and the lack of information regarding body distribution of inhaled nanoparticles may pose serious problem. In this study, we addressed this question by studying the body distribution of inhaled nanoparticles in mice using approximately 50-nm fluorescent magnetic nanoparticles (FMNPs) as a model of nanoparticles through nose-only exposure chamber system developed by our group. Scanning mobility particle sizer (SMPS) analysis revealed that the mice were exposed to FMNPs with a total particle number of 4.89 × 10 5 ± 2.37 × 10 4 /cm 3 (low concentration) and 9.34 × 10 5 ± 5.11 × 10 4 /cm 3 (high concentration) for 4 wk (4 h/d, 5 d/wk). The body distribution of FMNPs was examined by magnetic resonance imaging (MRI) and Confocal Laser Scanning Microscope (CLSM) analysis. FMNPs were distributed in various organs, including the liver, testis, spleen, lung and brain. T2-weighted spin-echo MR images showed that FMNPs could penetrate the blood-brain-barrier (BBB). Application of nanotechnologies should not produce adverse effects on human health and the Rapid Communicationenvironment. To predict and prevent the potential toxicity of nanomaterials, therefore, extensive studies should be performed under different routes of exposure with different sizes and shapes of nanomaterials. (J Occup Health 2008; 50: 1-6)

BACKGROUND AND PURPOSESoluble epoxide hydrolase inhibitors (sEHIs) possess anti-inflammatory, antiatherosclerotic, antihypertensive and analgesic properties. The pharmacokinetics (PK) and pharmacodynamics in terms of inhibitory potency of sEHIs were assessed in non-human primates (NHPs). Development of a sEHI for use in NHPs will facilitate investigations on the role of sEH in numerous chronic inflammatory conditions. EXPERIMENTAL APPROACHPK parameters of 11 sEHIs in cynomolgus monkeys were determined after oral dosing with 0.3 mg·kg -1. Their physical properties and inhibitory potency in hepatic cytosol of cynomolgus monkeys were examined. Dose-dependent effects of the two inhibitors 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) and the related acetyl piperidine derivative, 1-trifluoromethoxyphenyl-3-(1-acetylpiperidin-4-yl) urea (TPAU), on natural blood eicosanoids, were determined. KEY RESULTSAmong the inhibitors tested, TPPU and two 4-(cyclohexyloxy) benzoic acid urea sEHIs displayed high plasma concentrations (>10 ¥ IC50), when dosed orally at 0.3 mg·kg -1. Although the 4-(cyclohexyloxy) benzoic acid ureas were more potent against monkey sEH than piperidyl ureas (TPAU and TPPU), the latter compounds showed higher plasma concentrations and more drug-like properties. The Cmax increased with dose from 0.3 to 3 mg·kg -1 for TPPU and from 0.1 to 3 mg·kg -1 for TPAU, although it was not linear over this range of doses. As an indication of target engagement, ratios of linoleate epoxides to diols increased with TPPU administration. CONCLUSION AND IMPLICATIONSOur data indicate that TPPU is suitable for investigating sEH biology and the role of epoxide-containing lipids in modulating inflammatory diseases in NHPs. Abbreviations

The low efficiency of conventional therapies in achieving long-term survival of patients with lung cancer calls for development of novel treatment options. Although several genes have been investigated for their antitumor activities through gene delivery, problems surrounding the methods used, such as efficiency, specificity, and toxicity, hinder application of such therapies in clinical settings.

We have developed multifunctional fluorescent surface enhanced Raman spectroscopic tagging material (F-SERS dots) composed of silver nanoparticle-embedded silica spheres with fluorescent organic dye and specific Raman labels for multiplex targeting, tracking, and imaging of cellular/molecular events in the living organism. In this study, F-SERS dots fabricated with specific target antibodies (BAX and BAD) were employed for the detection of apoptosis. The F-SERS dots did not show any particular toxicity in several cell lines. The F-SERS dots could monitor the apoptosis effectively and simultaneously through fluorescent images as well as Raman signals in both cells and tissues with high selectivity. Our results clearly demonstrate that F-SERS dots can be easily applicable to multiplex analysis of diverse cellular/molecular events important for maintaining cellular homeostasis.

We hypothesized that the higher transfection efficiency of PEAs was the synergistic effect arising from hyperosmotic glycerol and endosomal buffering capacity of PEAs resulting from the presence of a glycerol backbone and PEI amine groups, respectively.

Inorganic phosphate (Pi) plays a key role in diverse physiological functions. Recently, considerable progress has been made in our understanding of the function and regulation of the brain-specific sodium-dependent inorganic phosphate transporter 1 (NPT1), which is found to exist principally in cerebrum and cerebellum. The potential importance of Pi as a novel signaling molecule and the poor prognosis of diverse neurodegenerative diseases that involve brain-specific NPT1 have prompted us to define the pathways by which Pi affects mouse brain growth. A high phosphate diet caused an increase in serum Pi accompanied by a decrease in calcium, and a decrease in body weight coupled with a decreased relative weight of cerebellum. A high phosphate diet caused a significant increase in protein expression of NPT1, both in cerebrum and cerebellum. Additionally, the high phosphate diet increased Homo sapiens v-akt murine thymoma viral oncogene homolog 1 (Akt) phosphorylation at Ser473 in cerebrum and cerebellum, whereas suppression of Akt phosphorylation at Thr308 was observed only in cerebellum. Selective suppression of eukaryotic translation initiation factor-binding protein (eIF4E-BP1) in cerebrum was induced by high levels of Pi, which induced cap-dependent and cap-independent protein translation in cerebrum and cerebellum, respectively. Phosphorylation of extracellular regulated kinase 1 (ERK1) in comparison with that of ERK2 was significantly reduced in both cerebrum and cerebellum. High levels of Pi reduced protein expressions of proliferating cell nuclear antigen (PCNA) and cyclin D1 in cerebrum and cerebellum. In conclusion, the results indicate that high dietary Pi can perturb normal brain growth, possibly through Akt-ERK signaling in developing mice.