Autophagy is induced under Zn limitation and contributes to Zn-limited stress tolerance in Arabidopsis (<i>Arabidopsis thaliana</i>)

<p>Autophagy is a degradation system for cellular components conserved in eukaryotes. In Arabidopsis, it is known that autophagy is crucial for growth under dark-induced carbon starvation and N deficiency. However, little is known about the relationship between autophagy and other nutrients. Here, we focused on the relationship between autophagy and Zn nutrition. We found that autophagy-deficient (<i>atg</i>) mutants showed an early senescence phenotype under Zn limitation and limited growth recovery from Zn limitation. Furthermore, we confirmed the induction of autophagy under Zn limitation by expression analysis of <i>autophagy-related</i> genes (<i>ATG</i>s) and imaging analysis of autophagic bodies with green fluorescent protein-ATG8a (GFP-ATG8a). In <i>atg</i> mutants, although the Zn concentrations were similar to those of the wild-type plants, the transcript levels of <i>Zn deficiency-inducible</i> genes fluctuated more, and O₂^– and H₂O₂ levels increased more than in wild-type plants. These results suggest that autophagy is involved in intracellular Zn usage and suppresses the accumulation of reactive oxygen species (ROS) generated by Zn limitation.</p

Chiral Crystal Structure of a <i>P</i>2₁2₁2₁ Kryptoracemate Iron(II) Complex with an Unsymmetric Azine Ligand and the Observation of Chiral Single Crystal Circular Dichroism

A chiral complex, [Fe­(HL)₂]­(PF₆)₂ (<b>1</b>), where HL denotes 2-pyridylmethylidenehydrazono-4-(2-methylimidazolyl)­methane, was prepared. X-ray structure analysis revealed that it crystallizes as a kryptoracemate of sesquihydrate chiral crystals in the orthorhombic noncentrosymmetric space group <i>P</i>2₁2₁2₁ (<i>Z</i> = 8, <i>Z</i>′ = 2). Two diastereomeric cationic complexes with opposite configuration reside within the asymmetric unit. KBr pellets prepared using selected single crystals showed enantiomorphous circular dichroism patterns

Structure and Dynamic Behavior of the Na–Crown Ether Complex in the Graphite Layers Studied by DFT and ¹H NMR

Diffusion of alkali metals in graphite layers is significant for the chemical and electrochemical properties of graphite intercalation compounds (GICs). Crown ethers co-intercalate into graphite with alkali metal (Na and K) cations and form ternary GICs. The structures and molecular dynamics of 15-crown-5 and 18-crown-6 ether coordinating to Na⁺ or K⁺ in GICs were investigated by DFT calculations and ¹H solid state NMR analyses. DFT calculations suggest a stacked structure of crown ether–metal complex with some offset. ¹H NMR shows two kinds of molecular motions at room temperature: isotropic rotation with molecular diffusion and axial rotation with fluctuation of the axis. The structure and dynamics of crown ether molecules in GIC galleries are strongly affected by the geometry of the crown ether molecules and the strength of the interaction between alkali metal and ligand molecules

Direct Information on Structure and Energetic Features of Cu⁺−Xe Species Formed in MFI-Type Zeolite at Room Temperature

The interacted species of Xe with metal ions that are stable at room temperature are not known and are a subject of interest for fundamental chemistry. We have experimentally found a new and stable Xe species, XeCu⁺, which was formed at room temperature in a copper ion-exchanged MFI-type zeolite. The presence of a prominent interaction between Cu⁺ in MFI and Xe, which has a covalent nature, was for the first time evidenced from experimental in situ synchrotron X-ray absorption fine structure and heat of adsorption measurements: the Cu⁺−Xe bond length of 2.45 Å and the bonding energy of ca. 60 kJ mol⁻¹. The bonding nature between Xe and Cu⁺ in the MFI zeolite was discussed utilizing density functional theory; the observed significant stabilization comes from the d(Cu⁺ in MFI)−p(Xe) orbital interaction. These new findings may pave a new way to developing fundamental chemistry of Xe compounds

Expression levels of <i>MEF2C</i> and <i>FLT3</i> in ETP-ALL vs. typical T-ALL blast cells.

<p>Comparison of the expression levels of <i>MEF2C</i> and <i>FLT3</i> in ETP-ALL vs. typical T-ALL blast cells determined by real-time quantitative-PCR analysis.</p

Comparison of LOUCY and Jurkat leukemia cells.

<p>(a) Expression of MEF2C and β-actin by western blot analyses. (b), (c) Cell growth inhibition of leukemia cells assessed by WST assay with serial concentrations of prednisolone (PSL) or ABT-737. (d) q-PCR analysis of BCL2 of two cell lines 12 hours after treatment of ABT-737 with the concentration of 10 or 100 nM. The bar indicates the mean±SE of two independent experiments in triplicate (e) Cell growth inhibition with serial concentrations of prednisolone (PSL) combined with ABT-737 (10 nM). (f) Calculation of the IC50 of PSL, following treatment of leukemic cells with either PSL, or a combination of PSL and ABT-737. Calculated combination Index of less than 1.0 was considered as a synergistic effect. (g), (h) Apoptosis study. Annexin V-positive cells were counted as apoptotic. Flow cytometry data in (g) and the mean±SE of three independent experiments in (h).</p

BCL2 Inhibitor (ABT-737): A Restorer of Prednisolone Sensitivity in Early T-Cell Precursor-Acute Lymphoblastic Leukemia with High <i>MEF2C</i> Expression?

<div><p>Early T-cell precursor-acute lymphoblastic leukemia (ETP-ALL) has been identified as a high-risk subtype of pediatric T-cell acute lymphoblastic leukemia (T-ALL). Conventional chemotherapy is not fully effective for this subtype of leukemia; therefore, potential therapeutic targets need to be explored. Analysis of the gene expression patterns of the transcription factors in pediatric T-ALL revealed that <i>MEF2C</i> and <i>FLT3</i> were expressed at higher levels in ETP-ALL than typical T-ALL. Using human T-ALL and BaF3 cell lines with high expression levels of <i>MEF2C</i>, the present study tested whether the BCL2 inhibitor (ABT-737) restores the sensitivity to prednisolone (PSL), because MEF2C causes PSL resistance, possibly by augmenting the anti-apoptotic activity of BCL2. Treatment with PSL and ABT-737 caused a significant reduction in the IC50 of PSL in the <i>MEF2C</i>-expressing LOUCY cells, in addition to the <i>MEF2C</i>-transduced BaF3 cells, but not in the non-<i>MEF2C</i>-expressing Jurkat cells. The combination treatment significantly accelerated the killing of primary leukemic blast cells of ETP-ALL with high expression levels of <i>MEF2C</i>, which were co-cultured with murine stromal cells. These findings suggest that BCL2 inhibitors may be a therapeutic candidate <i>in vivo</i> for patients with ETP-ALL with high expression levels of <i>MEF2C</i>.</p></div

Comparison of BaF3-MEF2C vs. BaF3-mock cells.

<p>(a) Expression of MEF2C and β-actin determined by western blot analysis. (b) The number of viable cells assessed using WST assay following incubation, with PSL (50 μM) and/or ABT-737 (200 and 400 nM). (c) Calculation of the IC50 of PSL when treated with PSL alone, or with a combination of PSL and ABT-737 (200 or 400 nM). P-value of less than 0.05 was considered statistically significant. *: p< 0.05. (d) q-PCR analysis of Bcl2 of two cell lines 12 hours after treatment of ABT-737 with the concentration of 200 or 400 nM. The bar indicates the mean±SE of two independent experiments in triplicate.</p

OsATG7 is required for autophagy-dependent lipid metabolism in rice postmeiotic anther development

<div><p>In flowering plants, the tapetum, the innermost layer of the anther, provides both nutrient and lipid components to developing microspores, pollen grains, and the pollen coat. Though the programmed cell death of the tapetum is one of the most critical and sensitive steps for fertility and is affected by various environmental stresses, its regulatory mechanisms remain mostly unknown. Here we show that autophagy is required for the metabolic regulation and nutrient supply in anthers and that autophagic degradation within tapetum cells is essential for postmeiotic anther development in rice. Autophagosome-like structures and several vacuole-enclosed lipid bodies were observed in postmeiotic tapetum cells specifically at the uninucleate stage during pollen development, which were completely abolished in a retrotransposon-insertional <i>OsATG7</i> (autophagy-related 7)-knockout mutant defective in autophagy, suggesting that autophagy is induced in tapetum cells. Surprisingly, the mutant showed complete sporophytic male sterility, failed to accumulate lipidic and starch components in pollen grains at the flowering stage, showed reduced pollen germination activity, and had limited anther dehiscence. Lipidomic analyses suggested impairment of editing of phosphatidylcholines and lipid desaturation in the mutant during pollen maturation. These results indicate a critical involvement of autophagy in a reproductive developmental process of rice, and shed light on the novel autophagy-mediated regulation of lipid metabolism in eukaryotic cells.</p></div