A molecular mechanism that confines the activity pattern of miR165 in Arabidopsis leaf primordia

In Arabidopsis leaf primordia, the expression of HD‐Zip III, which promotes tissue differentiation on the adaxial side of the leaf primordia, is repressed by miRNA165/166 (miR165/166). Small RNAs, including miRNAs, can move from cell to cell. In this study, HD‐Zip III expression was strikingly repressed by miR165/166 in the epidermis and parenchyma cells on the abaxial side of the leaf primordia compared with those on the adaxial side. We also found that the MIR165A locus, which was expressed in the abaxial epidermis, was sufficient to establish the rigid repression pattern of HD‐Zip III expression in the leaf primordia. Ectopic expression analyses of MIR165A showed that the abaxial‐biased miR165 activity in the leaf primordia was formed neither by a polarized distribution of factors affecting miR165 activity nor by a physical boundary inhibiting the cell‐to‐cell movement of miRNA between the adaxial and abaxial sides. We revealed that cis‐acting factors, including the promoter, backbone, and mature miRNA sequence of MIR165A, are necessary for the abaxial‐biased activity of miR165 in the leaf primordia. We also found that the abaxial‐determining genes YABBYs are trans‐acting factors that are necessary for the miR165 activity pattern, resulting in the rigid determination of the adaxial–abaxial boundary in leaf primordia. Thus, we proposed a molecular mechanism in which the abaxial‐biased patterning of miR165 activity is confined.     

Wheat bran protects Fischer-344 rats from diquat-induced oxidative stress by activating antioxidant system: selenium as an antioxidant

Wheat bran had a protective effect against diquat toxicity in rats fed a purified diet (PD). We studied the effects of wheat bran on the antioxidant system in the liver of rats treated with saline and diquat. Although feeding wheat bran did not affect the concentration of hepatic non-protein sulfhydryl or the activity of glucose 6-phosphate dehydrogenase in the saline-injected rats, these values were significantly higher in the rats fed PD containing wheat bran (W-PD) than in rats fed only PD after administering diquat. The glutathione peroxidase and reductase activities were significantly elevated by wheat bran in the saline-injected rats. Although the glutathione peroxidase activity was unchanged in both the PD-fed rats and W-PD-fed rats after the diquat treatment, the glutathione reductase activity was significantly decreased in both the PD-fed and W-PD-fed rats. Feeding the rats with PD containing 0.15 ppm selenium as well as with W-PD elevated the activity of hepatic glutathione peroxidase and attenuated the diquat toxicity. These results indicate that wheat bran protected against diquat toxicity by activating the hepatic antioxidant system, and that selenium was the key antioxidant in wheat bran.     

Amyloid β induces adhesion of erythrocytes to endothelial cells and affects endothelial viability and functionality

It has been suggested that amyloid β-peptide (Aβ) might mediate the adhesion of erythrocytes to the endothelium which could disrupt the properties of endothelial cells. We provide evidence here that Aβ actually induced the binding of erythrocytes to endothelial cells and decreased endothelial viability, perhaps by the generation of oxidative and inflammatory stress. These changes are likely to contribute to the pathogenesis of Alzheimer's disease.     

Development of a new class of benzoylpyrrole-based PPARα/γ activators

Starting with a subtle blood glucose-lowering effect of a TGF-β inhibitor, we designed and synthesized a series of benzoylpyrrole-based carboxylic acids as PPARs activators. Among these compounds, 10sNa exhibited favorable blood glucose-lowering effect without body weight gain. We assume that the beneficial effect of 10sNa is attributed to not only its compound PPARα agonistic activity but also its PPARγ partial agonistic activity.     

Degeneration of hrpZ gene in Pseudomonas syringae pv. tabaci to evade tobacco defence: an arms race between tobacco and its bacterial pathogen

The HrpZ harpin of Pseudomonas syringae is known to induce a hypersensitive response (HR) in some plants. In P. syringae pv. tabaci (Pta), the harpin gene hrpZ has been spontaneously disrupted by an internal deletion in its open reading frame and a frame shift. The loss of the ability of the recombinant harpin polypeptide of Pta to induce HR despite the high sensitivity of tobacco plants to harpin led us to investigate the meaning of the disrupted hrpZ gene in the virulence of Pta 6605. The hrpZ gene from P. syringae pv. pisi was introduced into wild-type (WT) Pta. The hrpZ-complemented Pta secreted harpin into the culture medium, but failed to cause disease symptoms by both infiltration and spray inoculation. Inoculation with the hrpZ-complemented Pta induced defence responses in tobacco plants, whereas the defence responses of tobacco plants were not prominent on inoculation with WT Pta. These results indicate that an ancestor of Pta might have disrupted hrpZ by an internal deletion to evade plant defences and confer the ability to cause disease in tobacco plants.     

Oxidative stress‐induced phosphorylation of JIP4 regulates lysosomal positioning in coordination with TRPML1 and ALG2

Retrograde transport of lysosomes is recognised as a critical autophagy regulator. Here, we found that acrolein, an aldehyde that is significantly elevated in Parkinson''s disease patient serum, enhances autophagy by promoting lysosomal clustering around the microtubule organising centre via a newly identified JIP4‐TRPML1‐ALG2 pathway. Phosphorylation of JIP4 at T217 by CaMK2G in response to Ca²⁺ fluxes tightly regulated this system. Increased vulnerability of JIP4 KO cells to acrolein indicated that lysosomal clustering and subsequent autophagy activation served as defence mechanisms against cytotoxicity of acrolein itself. Furthermore, the JIP4‐TRPML1‐ALG2 pathway was also activated by H₂O₂, indicating that this system acts as a broad mechanism of the oxidative stress response. Conversely, starvation‐induced lysosomal retrograde transport involved both the TMEM55B‐JIP4 and TRPML1‐ALG2 pathways in the absence of the JIP4 phosphorylation. Therefore, the phosphorylation status of JIP4 acts as a switch that controls the signalling pathways of lysosoma l distribution depending on the type of autophagy‐inducing signal.     

Identification of Biological Properties of Intralymphatic Tumor Related to the Development of Lymph Node Metastasis in Lung Adenocarcinoma

Background

Intralymphatic tumors in the extratumoral area are considered to represent the preceding phase of lymph node metastasis. The aim of this study was to clarify the biological properties of intralymphatic tumors susceptible to the development of lymph node metastasis, with special reference to the expression of cancer initiating/stem cell (CIC/CSC) related markers in cancer cells and the number of infiltrating stromal cells.

Material and Methods

Primary lung adenocarcinomas with lymphatic permeation in the extratumoral area were retrospectively examined (n = 107). We examined the expression levels of CIC/CSC related markers including ALDH1, OCT4, NANOG, SOX2 and Caveolin-1 in the intralymphatic cancer cells to evaluate their relationship to lymph node metastasis. Moreover, the number of infiltrating stromal cells expressing CD34, α-smooth muscle actin, and CD204 were also evaluated.

Results

Among the intralymphatic tissues, low ALDH1 expression in cancer cells, high SOX2 expression in cancer cells, and a high number of CD204(+) macrophages were independent predictive factors for lymph node metastasis (P = 0.004, P = 0.008, and P = 0.028, respectively). Among these factors, only low ALDH1 expression in cancer cells was significantly correlated with the farther spreading of lymph node metastasis (mediastinal lymph node, pathological N2) (P = 0.046) and the metastatic lymph node ratio (metastatic/resected) (P = 0.028). On the other hand, in the primary tumors, ALDH1 expression in the cancer cells was not associated with lymph node metastasis. Intralymphatic cancer cells expressing low ALDH1 levels exhibited lower E-cadherin expression levels than cancer cells with high levels of ALDH1 expression (P = 0.015).

Conclusions

Intralymphatic cancer cells expressing low levels of ALDH1 and infiltrating macrophages expressing CD204 have a critical impact on lymph node metastasis. Our study also highlighted the significance of evaluating the biological properties of intralymphatic tumors for tumor metastasis.     

Effect of Exogenous Fatty Acids on the Cellular Fatty Acid Composition and Neomycin Formation in a Mutant Strain of Streptomyces fradiae

A mutant of Streptomyces fradiae which requires oleic acid for neomycin formation was isolated and the effects of exogenous fatty acids and other additives on the formation of neomycin were studied. Palmitic acid and high concentration of sodium ions could replace oleic acid in neomycin formation. The fatty acid spectrum of the mutant strain ST–5B was quite different from that of the parent strain 3123. The major fatty acid components of the mutant and the parent were anteiso 15:0 and iso 16: 0, respectively. However the fatty acid composition of the mutant was changed from the anteiso 15: 0-type to the parental iso 16: 0-type by the supplement of oleic acid or high concentration of sodium ions in the medium. In the case of palmitic acid, the major fatty acid component of the mutant cells was changed from anteriso 15: 0 to normal 16:0. The role of these additives in neomycin formation by the mutant is discussed.     

Identification of a neural cell specific variant of microtubule-associated protein 4

The microtubule-binding domain of MAP4, a ubiquitous microtubule-associated protein, contains a region rich in proline and basic residues (proline-rich region). We searched the bovine adrenal gland for MAP4 isoforms, and identified a novel variant lacking 72 consecutive amino acid residues within the proline-rich region, as compared with the full-length MAP4. The amino acid sequence of the missing region was highly conserved (about 85% identity/similarity) among the corresponding regions of bovine, human, mouse, and rat MAP4, which suggested the functional significance of this region. A comparison of the genomic sequence with the cDNA sequence revealed that the missing region is encoded by a single exon. A MAP4 variant cDNA homologous to the bovine form was also detected in rat cells, suggesting that the new variant can be generated by alternative splicing, not only in bovine but also in other mammalian species. The mRNA expression of the novel isoform was restricted to the brain and the adrenal medulla, suggesting that this isoform is specific to a certain cell type. Using a bacterially expressed fragment corresponding to the microtubule-binding domain of the novel isoform, we analyzed its in vitro characteristics. The fragment induced microtubule assembly and bound to preformed microtubules, but the activities were slightly lower than those of the conventional MAP4 fragment, which carries the full-length proline-rich region. The microtubules assembled in the presence of the fragment failed to be bundled. Instead, a constant spacing between neighboring microtubules was observed.