Modified high-density lipoprotein modulates aldosterone release through scavenger receptors via extra cellular signal-regulated kinase and Janus kinase-dependent pathways

A proliferation-inducing ligand (APRIL) is overexpressed in most tumor cells and tissues, especially in tumors of the alimentary system, such as colorectal cancer (CRC), gastric cancer, and liver cancer. RNA interference (RNAi) has been proved to be a powerful tool for gene knockdown and holds great promise for the treatment of cancer. In this study, the efficacy of RNAi targeting APRIL was analyzed via relevant experiments on human CRC xenografted in BALB/c nude mice. Both the mRNA and protein levels of APRIL were examined after intratumoral injection of APRIL small interfering RNA (siRNA). Meanwhile, pathological tools were utilized to observe the alterations on the aspects of proliferation, metastasis, apoptosis and cellular necrosis by means of detecting proliferating cell nuclear antigen, Ki-67, MMP-2, MMP-9, TIMP-3, TIMP-4, Bcl-2, Bax and Bcl-xL of CRC. In addition, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) and hematoxylin and eosin staining were also conducted to examine cell apoptosis and necrosis. It was found that grafted human colorectal tumor growth and metastasis were obviously inhibited while tumor cell apoptosis and necrosis were induced after in vivo APRIL siRNA injection into nude mice. The data indicated that silencing of the APRIL gene using RNAi may serve as a novel therapeutic strategy for treatment of CRC.     

Myc regulates keratinocyte adhesion and differentiation via complex formation with Miz1

Myc plays a key role in homeostasis of the skin. We show that Miz1, which mediates Myc repression of gene expression, is expressed in the epidermal basal layer. A large percentage of genes regulated by the Myc-Miz1 complex in keratinocytes encode proteins involved in cell adhesion, and some, including the alpha6 and beta1 integrins, are directly bound by Myc and Miz1 in vivo. Using a Myc mutant deficient in Miz1 binding (MycV394D), we show that Miz1 is required for the effects of Myc on keratinocyte responsiveness to TGF-beta. Myc, but not MycV394D, decreases keratinocyte adhesion and spreading. In reconstituted epidermis, Myc induces differentiation and loss of cell polarization in a Miz1-dependent manner. In vivo, overexpression of beta1 integrins restores basal layer polarity and prevents Myc-induced premature differentiation. Our data show that regulation of cell adhesion is a major function of the Myc-Miz1 complex and suggest that it may contribute to Myc-induced exit from the epidermal stem cell compartment.     

Harmonization is more important than experience—results of the first Nordic–Baltic diatom intercalibration exercise 2007 (stream monitoring)

The goal of this study was a harmonization of diatom identification and counting among diatomists from the Scandinavian and Baltic countries to improve the comparison of diatom studies in this geographical area. An analysis of the results of 25 diatomists following the European standard EN 14407 during an intercalibration exercise showed that a high similarity was achieved by harmonization and not because of a long experience with diatoms. Sources of error were wrong calibration scales, overlooking of small taxa, especially small Navicula s.l., misidentifications (Eunotia rhomboidea was mistaken for Eunotia incisa) and unclear separation between certain taxa in the identification literature. The latter was discussed during a workshop with focus on the Achnanthes minutissima group, the separation of Fragilaria capucina var. gracilis from F. capucina var. rumpens, and Nitzschia palea var. palea from N. palea var. debilis. The exercise showed also that the Swedish standard diatom method tested here worked fine with acceptable error for the indices IPS (Indice de Polluo-sensibilité Spécifique) and ACID (ACidity Index for Diatoms) when diatomists with a low similarity (Bray–Curtis <60%) with the auditor in at least one of the samples are excluded.     

The Myosin Motor Domain of Fungal Chitin Synthase V Is Dispensable for Vesicle Motility but Required for Virulence of the Maize Pathogen Ustilago maydis

Class V chitin synthases are fungal virulence factors required for plant infection. They consist of a myosin motor domain fused to a membrane-spanning chitin synthase region that participates in fungal cell wall formation. The function of the motor domain is unknown, but it might deliver the myosin chitin synthase-attached vesicles to the growth region. Here, we analyze the importance of both domains in Mcs1, the chitin synthase V of the maize smut fungus Ustilago maydis. By quantitative analysis of disease symptoms, tissue colonization, and single-cell morphogenic parameters, we demonstrate that both domains are required for fungal virulence. Fungi carrying mutations in the chitin synthase domain are rapidly recognized and killed by the plant, whereas fungi carrying a deletion of the motor domain show alterations in cell wall composition but can invade host tissue and cause a moderate plant response. We also show that Mcs1-bound vesicles exhibit long-range movement for up to 20 μm at a velocity of ~1.75 μm/s. Apical Mcs1 localization depends on F-actin and the motor domain, whereas Mcs1 motility requires microtubules and persists when the Mcs1 motor domain is deleted. Our results suggest that the myosin motor domain of ChsV supports exocytosis but not long-range delivery of transport vesicles.     

The Arf tumor suppressor protein inhibits Miz1 to suppress cell adhesion and induce apoptosis

Oncogenic stress induces expression of the alternate reading frame (Arf) tumor suppressor protein. Arf then stabilizes p53, which leads to cell cycle arrest or apoptosis. The mechanisms that distinguish both outcomes are incompletely understood. In this study, we show that Arf interacts with the Myc-associated zinc finger protein Miz1. Binding of Arf disrupts the interaction of Miz1 with its coactivator, nucleophosmin, induces the sumoylation of Miz1, and facilitates the assembly of a heterochromatic complex that contains Myc and trimethylated H3K9 in addition to Miz1. Arf-dependent assembly of this complex leads to the repression of multiple genes involved in cell adhesion and signal transduction and induces apoptosis. Our data point to a tumor-suppressive pathway that weakens cell–cell and cell–matrix interactions in response to expression of Arf and that may thereby facilitate the elimination of cells harboring an oncogenic mutation.     

Crystallization and preliminary X-ray crystallographic analysis of the N-terminal photosensory module of phytochrome Agp1, a biliverdin-binding photoreceptor from Agrobacterium tumefaciens

Phytochromes are photochromic photoreceptors with a bilin chromophore that have been found in plants and bacteria. Typical bacterial phytochromes are composed of an N-terminal photosensory chromophore module and a C-terminal protein kinase. The former contains the chromophore, which allows phytochromes to adopt the two interconvertible spectral forms, Pr and Pfr. The N-terminal photosensory module of Agrobacterium phytochrome Agp1, Agp1-M15, was used for crystallization studies. The protein was either assembled with the natural chromophore biliverdin or a sterically locked synthetic biliverdin-derivative, termed 15Za. The last-named adduct does not undergo photoisomerization due to an additional carbon chain between the rings C and D of the chromophore. Both adducts could be crystallized, but the resolution was largely improved by the use of 15Za. Crystals of biliverdin-Agp1-M15 diffract to 6A resolution and belong to the tetragonal space group I422 with unit cell dimensions a = b = 171 Angstroms, c = 81 Angstroms, crystals of 15Za-Agp1-M15 belong to the same space group with similar unit cell dimensions a = b = 174 Angstroms, c = 80 Angstroms, but diffract to 3.4 Angstroms resolution. Assuming the asymmetric unit to be occupied by one monomer of 55kDa, the unit cell contains 54-55% solvent with a crystal volume per protein mass, V(m), of 2.7 Angstroms(3) Da(-1).     

Simultaneous enantioselective analysis of chiral urinary metabolites in patients with Zellweger syndrome

Enantio-MDGC-MS analysis with heptakis-(2,3-di-O-methyl-6-O-tert.-butyl-dimethylsilyl)-beta-cyclodextrin as the chiral main column is a powerful tool for the separation of chiral compounds. This paper reports on the simultaneous stereodifferentiation of 2-hydroxyisocaproic acid (HICA), 3-methyladipic acid (3-MA), 2-hydroxyglutaric acid (2-HG), 3-(4-hydroxyphenyl)-lactic acid (HPLA), 2-hydroxysebacic acid (2-HS) and 3-hydroxysebacic acid (3-HS) in a single chromatographic run. These chiral urinary metabolites are useful in the diagnosis of peroxisomal diseases such as Zellweger syndrome (ZS). In this investigation, urine samples from nine patients with ZS were analysed in order to reveal the enantiomeric ratio of these chiral metabolites. The stereodifferentiation of the analysed chiral compounds may provide important information on their biochemical origin.