Epithelial-specific histone modification of the <Emphasis Type="Italic">miR-96/182</Emphasis> locus targeting <Emphasis Type="Italic">AMAP1</Emphasis> mRNA predisposes p53 to suppress cell invasion in epithelial cells

Background

TP53 mutations in cancer cells often evoke cell invasiveness, whereas fibroblasts show invasiveness in the presence of intact TP53. AMAP1 (also called DDEF1 or ASAP1) is a downstream effector of ARF6 and is essential for the ARF6-driven cell-invasive phenotype. We found that AMAP1 levels are under the control of p53 (TP53 gene product) in epithelial cells but not in fibroblasts, and here addressed that molecular basis of the epithelial-specific function of p53 in suppressing invasiveness via targeting AMAP1.

Methods

Using MDA-MB-231 cells expressing wild-type and p53 mutants, we identified miRNAs in which their expression is controlled by normal-p53. Among them, we identified miRNAs that target AMAP1 mRNA, and analyzed their expression levels and epigenetic statuses in epithelial cells and nonepithelial cells.

Results

We found that normal-p53 suppresses AMAP1 mRNA in cancer cells and normal epithelial cells, and that more than 30 miRNAs are induced by normal-p53. Among them, miR-96 and miR-182 were found to target the 3′-untranslated region of AMAP1 mRNA. Fibroblasts did not express these miRNAs at detectable levels. The ENCODE dataset demonstrated that the promoter region of the miR-183-96-182 cistron is enriched with H3K27 acetylation in epithelial cells, whereas this locus is enriched with H3K27 trimethylation in fibroblasts and other non-epithelial cells. miRNAs, such as miR-423, which are under the control of p53 but not associated with AMAP1 mRNA, demonstrated similar histone modifications at their gene loci in epithelial cells and fibroblasts, and were expressed in these cells.

Conclusion

Histone modifications of certain miRNA loci, such as the miR-183-96-182 cistron, are different between epithelial cells and non-epithelial cells. Such epithelial-specific miRNA regulation appears to provide the molecular basis for the epithelial-specific function of p53 in suppressing ARF6-driven invasiveness.

     

Pulmonary carcinosarcoma showing an obvious response to pazopanib: a case report

Background

Pulmonary carcinosarcoma (PCS) is a rare primary lung malignancy and has a poor prognosis among lung tumor histological subtypes. However, an appropriate treatment strategy has not been developed for unresectable PCS.

Case presentation

A 65-year-old man who was diagnosed with PCS was treated by surgical removal of the primary lung lesion, followed by six cycles of adjuvant chemotherapy with cisplatin plus irinotecan. Following the chemotherapy, he experienced a relapse with brain metastasis, which induced the rapid onset of left leg paralysis. Radical surgical resection and stereotactic radiosurgery to the resection cavity were performed. However, meningeal dissemination and new lung metastases occurred after a year and half. To control these multiple metastatic lesions, the patient was treated with the multiple kinase inhibitor pazopanib. No change was observed in the meningeal dissemination, while the metastatic lung lesions were prominently reduced in size following treatment with pazopanib. Consequently, the patient showed a partial response to pazopanib treatment, although the dose of pazopanib was reduced by half as a result of thrombocytopenia.

Conclusion

This is the first report of metastatic PCS showing an evident therapeutic response to tumor-targeted therapy. We suggest that pazopanib may be a therapeutic option for patients with metastatic PCS.

     

Novel Defense by Metallothionein Induction Against Cognitive Decline: From Amyloid β<Subscript>1–42</Subscript>-Induced Excess Zn<Superscript>2+</Superscript> to Functional Zn<Superscript>2+</Superscript> Deficiency

The role of metallothioneins (MTs) in cognitive decline associated with intracellular Zn²⁺ dysregulation remains unclear. Here, we report that hippocampal MT induction defends cognitive decline, which was induced by amyloid β_1–42 (Aβ_1–42)-mediated excess Zn²⁺ and functional Zn²⁺ deficiency. Excess increase in intracellular Zn²⁺, which was induced by local injection of Aβ_1–42 into the dentate granule cell layer, attenuated in vivo perforant pathway LTP, while the attenuation was rescued by preinjection of MT inducers into the same region. Intraperitoneal injection of dexamethasone, which increased hippocampal MT proteins and blocked Aβ_1–42-mediated Zn²⁺ uptake, but not Aβ_1–42 uptake, into dentate granule cells, also rescued Aβ_1–42-induced impairment of memory via attenuated LTP. The present study indicates that hippocampal MT induction blocks rapid excess increase in intracellular Zn²⁺ in dentate granule cells, which originates in Zn²⁺ released from Aβ_1–42, followed by rescuing Aβ_1–42-induced cognitive decline. Furthermore, LTP was vulnerable to Aβ_1–42 in the aged dentate gyrus, consistent with enhanced Aβ_1–42-mediated Zn²⁺ uptake into aged dentate granule cells, suggesting that Aβ_1–42-induced cognitive decline, which is caused by excess intracellular Zn²⁺, can more frequently occur along with aging. On the other hand, attenuated LTP under functional Zn²⁺ deficiency in dentate granule cells was also rescued by MT induction. Hippocampal MT induction may rescue cognitive decline under lack of cellular transient changes in functional Zn²⁺ concentration, while its induction is an attractive defense strategy against Aβ_1–42-induced cognitive decline.     

Characterization of tetrathionate hydrolase from the marine acidophilic sulfur-oxidizing bacterium,Acidithiobacillus thiooxidans strain SH

Tetrathionate hydrolase (4THase), a key enzyme of the S₄-intermediate (S4I) pathway, was partially purified from marine acidophilic bacterium, Acidithiobacillus thiooxidans strain SH, and the gene encoding this enzyme (SH-tth) was identified. SH-Tth is a homodimer with a molecular mass of 97 ± 3 kDa, and contains a subunit 52 kDa in size. Enzyme activity was stimulated in the presence of 1 M NaCl, and showed the maximum at pH 3.0. Although 4THases from A. thiooxidans and the closely related Acidithiobacillus caldus strain have been reported to be periplasmic enzymes, SH-Tth seems to be localized on the outer membrane of the cell, and acts as a peripheral protein. Furthermore, both 4THase activity and SH-Tth proteins were detected in sulfur-grown cells of strain SH. These results suggested that SH-Tth is involved in elemental sulfur-oxidation, which is distinct from sulfur-oxidation in other sulfur-oxidizing strains such as A. thiooxidans and A. caldus.     

Cyclic analogue of S-benzylisothiourea that suppresses kynurenine production without inhibiting indoleamine 2,3-dioxygenase activity

Kynurenine is biosynthesised from tryptophan catalysed by indoleamine 2,3-dioxygenase (IDO). The abrogation of kynurenine production is considered a promising therapeutic target for immunological cancer treatment. In the course of our IDO inhibitor programme, formal cyclisation of the isothiourea moiety of the IDO inhibitor 1 afforded the 5-Cl-benzimidazole derivative 2b-6, which inhibited both recombinant human IDO (rhIDO) activity and cellular kynurenine production. Further derivatisation of 2b-6 provided the potent inhibitor of cellular kynurenine production 2i (IC₅₀?=?0.34?µM), which unexpectedly exerted little effect on the enzymatic activity of rhIDO. Elucidation of the mechanism of action revealed that compound 2i suppresses IDO expression at the protein level by inhibiting STAT1 expression in IFN-γ-treated A431 cells. The kynurenine-production inhibitor 2i is expected to be a promising starting point for a novel approach to immunological cancer treatment.     

Spontaneous intracranial hypotension is diagnosed by a combination of lipocalin-type prostaglandin D synthase and brain-type transferrin in cerebrospinal fluid

Background

Spontaneous intracranial hypotension (SIH) is caused by cerebrospinal fluid (CSF) leakage. Definitive diagnosis can be difficult by clinical examinations and imaging studies.

Environment and landscape rather than planting design are the drivers of success in long‐term restoration of riparian Atlantic forest

Question

Identifying the factors that lead to the success of restoration projects has been a major challenge in ecological restoration. Here we ask which factors, aside from time since restoration began, drive the recovery of tree biomass, density and richness of the understorey in riparian forests undergoing restoration.

Location

Semideciduous Atlantic Forest with tropical climate and deep, fertile soils, southeast Brazil.

Methods

We sampled tree basal area (DBH ≥ 5 cm), density and richness of the understorey (DBH < 5 cm) in 26 riparian forests undergoing restoration (a chronosequence spanning 4–53 years). We assessed the following variables as possible factors, besides time, influencing community attributes: (1) planting design: density and richness of seedlings planted; (2) landscape features: proximity index measuring forest cover within a 1.5‐km radius, distance and size of the nearest forest remnant; and (3) environmental factors: invasive grasses, soil fertility, drought, average annual precipitation and proportion of fine particles in the soil. We performed correlation analyses including predictor and response variables, followed by stepwise backward regression (AIC), multiple and simple linear regressions, to investigate the relationships between those factors and the community attributes.

Results

Tree basal area was primarily influenced by the proportion of small particles in the soil (+) and secondarily by rainfall (?). Understorey richness was influenced by the combination of size (+) and distance (?) of the nearest patch, rainfall (?) and soil fertility (+). Understorey density was primarily influenced by the size of the nearest forest remnant (+) and secondarily by invasive grasses (?). No influence of density or richness of the seedlings planted was observed.

Conclusion

Environmental factors and landscape configuration drive the recovery of tree biomass, density and richness in communities undergoing restoration. The most relevant ecological filters influencing restoration success are availability of soil water and nutrients and the distance and size of the nearest remnant of native vegetation. The expected influence of richness and density of seedlings planted, considered for many years as important drivers of forest restoration success, was not confirmed in this study.     

Cantharidin world in air: Spatiotemporal distributions of flying canthariphilous insects in the forest interior

The natural community in which the members interact using a toxic terpenoid cantharidin is named the “cantharidin world.” In previous studies, however, the members of this world have been surveyed only on the forest floor by setting pitfall traps with cantharidin as an attractant. In this study, we set cantharidin traps at various heights above the forest floor to investigate the structure and functional diversity of the canthariphilous flying insect community in the forest above‐ground space. A total of 3,168 arthropods were collected by the traps; among them, six species were more attracted to cantharidin than to control traps. Pseudopyrochroa brevitarsis and P. laticollis (Colecoptera: Pyrochroidae) both appeared for a short time during spring, but the latter species tended to use a lower layer of the forest. Clavicollis fugiens (Coleoptera: Anthicidae) also appeared in spring and flew near the ground. In these beetles, the attracted individuals were mostly males; they may use the obtained cantharidin for nuptial gifts to the female. Atrichopogon femoralis, A. insularis and Atrichopogon sp. (Diptera: Ceratopogonidae) were collected widely in the forest above‐ground space. These midges were almost females, probably because only females of these insects use chemical cues, including cantharidin, for searching for arthropods from which to suck hemolymph.     

Comparative analysis of microbial diversity and bacterial seedling disease‐suppressive activity in organic‐farmed and standardized commercial conventional soils for rice nursery cultivation

The outbreak of rice plant diseases can be effectively suppressed in organic farming systems. However, the mechanisms of disease suppression by organic farming systems are not well understood. When Burkholderia‐infected rice seeds were sown and cultivated on nine organic‐farmed soils which were supplied by nine independent organic rice farmers or standardized commercial conventional soils, the emergence of bacterial seedling diseases was suppressed to equivalent degrees in nine organic‐farmed soils, whereas the diseases occurred in two commercial conventional soils. In any organic or commercial conventional soil sown with healthy rice seeds as a control, the diseases did not appear. Upon physicochemical analysis of the nine organic‐farmed soils, component common to these organic‐farmed soils seemed to not be directly associated with disease‐suppressive activity. However, microbiome analyses indicated that the bacterial population in these nine organic‐farmed soils was more diverse than those in commercial conventional soils. Intriguingly, the diverse bacterial population structures of organic‐farmed soils were preserved after irrigating and sowing rice seeds, but that of commercial conventional soils was clearly changed by them. Thus, organic‐farmed soils seem to maintain robust bacterial populations despite the irrigation and seedling growth. Indeed, pathogenic Burkholderia in infected rice seeds also did not proliferate in the seedling grown on organic‐farmed soils. Taken together, the common feature of organic‐farmed soils might be the correlation between bacterial seedling disease‐suppressive activity and higher robustness of the diversified microbiome.