Origin, evolution and diversification of plant ARGONAUTE proteins.

Argonaute (AGO) proteins are central players in RNA interference in eukaryotes. They associate with small RNAs (sRNA) and lead to transcriptional or posttranscriptional silencing of targets, thereby regulating diverse biological processes. The molecular and biological functions of AGO proteins have been extensively characterized, particularly in a few angiosperm species, leading to the recognition that the AGO family has expanded to accommodate diverse sRNAs thereby performing diverse biological functions. However, understanding of the expansion of AGO proteins in plants is still limited, due to a dearth of knowledge of AGO proteins in green algal groups. Here, we identified more than 2900 AGO proteins from 244 plant species, including green algae, and performed a large-scale phylogenetic analysis. The phylogeny shows that the plant AGO family gave rise to four clades after the emergence of hydrobiontic algae and prior to the emergence of land plants. Subsequent parallel expansion in ferns and angiosperms resulted in eight main clades in angiosperms: AGO2, AGO7, AGO6, AGO4, AGO1, AGO10a, AGO10b and AGO5. On the basis of this phylogeny, we identified two novel AGO4 orthologs that Arabidopsis does not have, and redefined AGO10, which is composed of AGO10a and AGO10b. Finally, we propose a hypothetical evolutionary model of AGO proteins in plants. Our studies provide a deeper understanding of the phylogenetic relationships of AGO family members in the green lineage, which would help to further reveal their roles as RNAi effectors.

TRANS-ACTING SIRNA3-derived short interfering RNAs confer cleavage of mRNAs in rice.

Plant TRANS-ACTING SIRNA3 (TAS3)-derived short interfering RNAs (siRNAs) include tasiR-AUXIN RESPONSE FACTORs (ARFs), which are functionally conserved in targeting ARF genes, and a set of non-tasiR-ARF siRNAs, which have rarely been studied. In this study, TAS3 siRNAs were systematically characterized in rice (Oryza sativa). Small RNA sequencing results showed that an overwhelming majority of TAS3 siRNAs belong to the non-tasiR-ARF group, while tasiR-ARFs occupy a diminutive fraction. Phylogenetic analysis of TAS3 genes across dicot and monocot plants revealed that the siRNA-generating regions were highly conserved in grass species, especially in the Oryzoideae. Target genes were identified for not only tasiR-ARFs but also non-tasiR-ARF siRNAs by analyzing rice Parallel Analysis of RNA Ends datasets, and some of these siRNA-target interactions were experimentally confirmed using tas3 mutants generated by genome editing. Consistent with the de-repression of target genes, phenotypic alterations were observed for mutants in three TAS3 loci in comparison to wild-type rice. The regulatory role of ribosomes in the TAS3 siRNA-target interactions was further revealed by the fact that TAS3 siRNA-mediated target cleavage, in particular tasiR-ARFs targeting ARF2/3/14/15, occurred extensively in rice polysome samples. Altogether, our study sheds light into TAS3 genes in plants and expands our knowledge about rice TAS3 siRNA-target interactions.

Multiomics Reveals the Regulatory Mechanisms of Arabidopsis Tissues under Heat Stress.

Understanding the mechanisms of responses to high temperatures in Arabidopsis will provide insights into how plants may mitigate heat stress under global climate change. And exploring the interconnections of different modification levels in heat stress response could help us to understand the molecular mechanism of heat stress response in Arabidopsis more comprehensively and precisely. In this paper, we combined multiomics analyses to explore the common heat stress-responsive genes and specific heat-responsive metabolic pathways in Arabidopsis leaf, seedling, and seed tissues. We found that genes such as AT1G54050 play a role in promoting proper protein folding in response to HS (Heat stress). In addition, it was revealed that the binding profile of A1B is altered under elevated temperature conditions. Finally, we also show that two microRNAs, ath-mir156h and ath-mir166b-5p, may be core regulatory molecules in HS. Also elucidated that under HS, plants can regulate specific regulatory mechanisms, such as oxygen levels, by altering the degree of CHH methylation.

Decreased expression of SVEP1 is closely related to a cancer stem cell-like phenotype and poor prognosis in hepatocellular carcinoma.

The objective of this study was to investigate the expression of SVEP1 in hepatocellular carcinoma (HCC) and to evaluate the association among SVEP1, cancer stem cell-like phenotype, and the prognosis of patients to provide new possibilities for the accurate diagnosis and stratification of HCC. Two hundred HCC and paired adjacent tissues were analyzed by immunohistochemistry and scored, and their relationships with clinicopathological parameters and survival rates were analyzed. We found that compared with adjacent tissues, the expression of SVEP1 in HCC was relatively low and was closely related to tumor size, satellite nodule formation, and histological grade (p<0.05). Statistical analysis showed that the survival rate of patients with low expression of SVEP1 decreased significantly (p<0.05). Our results showed that the expression of SVEP1 was negatively correlated with the expression of the cancer stem cell markers CD44 and CD133 (p<0.05). Moreover, multivariate Cox regression analysis showed that SVEP1 was an independent prognostic factor for the survival of HCC patients. In conclusion, our results suggest that decreased SVEP1 expression may promote HCC acquisition of a cancer stem cell-like phenotype, ultimately leading to heterogeneity and poor prognosis of HCC. This work may provide new insight into the development of HCC and suggests a potential marker for predicting the prognosis of patients.

Design and synthesis of reversible solid-state photochromic pyrazolones by introducing a pyridine ring.

We demonstrate a new strategy for designing reversibility, fatigue resistance and fluorescence switching materials, which are based on pyrazolone derivatives by introducing a pyridine ring. The reversible "on" and "off" modulation of fluorescence emission was up to 95% in the solid state.

let-7 microRNAs induce tamoxifen sensitivity by downregulation of estrogen receptor α signaling in breast cancer.

MicroRNAs (miRNAs) play an important regulatory role in breast tumorigenesis. Previously, we found that let-7 miRNAs were downregulated significantly in formalin-fixed paraffin-embedded (FFPE) breast cancer tissues. In this study, we further found that endogenous levels of let-7b and let-7i miRNAs are inversely correlated with levels of estrogen receptor (ER)-a36, a new variant of ER-α66, in the FFPE tissue set. Bioinformatic analysis suggested that ER-α36 may be another target of let-7 miRNAs. To test this hypothesis, cotransfection of let-7 mimics or inhibitors together with full-length or a fragment of ER-α36 3'UTR luciferase construct was performed, and we found that let-7b and let-7i mimics suppressed the activity of reporter gene significantly, which was enhanced remarkably by let-7b and let-7i inhibitors. Both mRNA and protein expression of ER-α36 were inhibited by let-7 mimics and enhanced by let-7 inhibitors. Furthermore, ER-α36 mediated nongenomic MAPK and Akt pathways were weakened by let-7b and let-7i mimics in triple negative breast cancer cell line MDA-MB-231. The reverse correlation between let-7 miRNAs and ER-α36 also exists in Tamoxifen (Tam)-resistant MCF7 cell line. Transfection of let-7 mimics to Tam-resistant MCF7 cells downregulated ER-α36 expression and enhanced the sensitivity of MCF7 cells to Tam in estrogen-free medium, which could be restored by overexpression of ER-α36 constructs without 3'UTR. Our results suggested a novel regulatory mechanism of let-7 miRNAs on ER-α36 mediated nongenomic estrogen signal pathways and Tam resistance.

Photochromism of a pyrazolone derivative in crystalline state and in HPMC composite film.

A novel photochromic compound, 1,3-diphenyl-4-(3-chloro-4-fluorobenzal)-5-hydoxypyrazole 4-phenylsemicarbazide (1a), has been synthesized by introducing a phenylsemicarbazide unit. The material exhibits good fatigue resistance and reversible fluorescent switching properties with distinct fluorescence on/off ratio under alternating UV irradiation and heating at 120 °C. For the fabrication of actual application materials, 1a/hydroxypropylmethylcellulose (HPMC) composite film has been successfully fabricated using hydrogel casting method. The 1a/HPMC composite film obtained can also show reversible photochromic reaction under UV irradiation and rapid thermal bleaching properties by heating. The HPMC composite film shows similar good photochromic properties as those of 1 in the crystalline state.

Influence of additives on potassium retention behaviors during straw combustion: A mechanism study.

The potassium retention behaviors of wheat stalk and its modification mechanisms in an oxidizing atmosphere by three additives [kaolinite, fly ash from Jincheng coal fluidized-bed gasification (JFA), and ammonium dihydrogen phosphate (ADP)] were investigated. The potassium retention ratios (PRRs) increased with increasing additive mass ratio. The ADP was the optimal selection for wheat stalks combustion when the three additives at the same mass ratio because of its highest PRR and a slow decrease in PRR with an increase in temperature. With the increasing three additive mass ratios, the PRRs of their mixed ashes showed a similar trend [rapid increase (<12%) and then a slow increase (12%-15%)]. The mass ratios of three additives were all <1.0% and their mixed ash reached an appropriate PRR. For kaolinite or JFA, the formations of K-Al/Fe silicates prompted an increase in the PRR. For ADP, K-Ca/Mg phosphate generations increased the PRR.

The novel miR-1269b-regulated protein SVEP1 induces hepatocellular carcinoma proliferation and metastasis likely through the PI3K/Akt pathway.

Decreased intercellular adhesion is a key step in the metastasis and recurrence of many cancers, including hepatocellular carcinoma (HCC). SVEP1 is an important cell adhesion molecule that plays a key role in regulating intercellular adhesion and embryonic lymphatic development. However, the expression patterns and roles of SVEP1 in HCC are still largely unknown. We identified SVEP1 expression by analyzing 220 HCC samples from our cancer center. TCGA and GEO online-databases were used for data calibration and validation. SVEP1 was differentially expressed in two groups of HCCs with different risks of recurrence and was deemed as an independent risk factor for the prognosis of HCC. The expression of SVEP1 is negatively related to the proliferation and metastasis of HCC. Downregulation of SVEP1 expression promoted in vitro HCC cell migration, chemotaxis, invasion and proliferation, as well as in vivo tumor growth, local invasion and metastasis in a mouse model. Bioinformatic analysis and RT-PCR results showed that miR-1269b expression is negatively correlated with the SVEP1 expression and the prognosis of HCC patients. Further experiments showed that miR-1269b directly targets and downregulates the expression of SVEP1, which further induces the phosphorylation of Akt at thr308. These regulatory effects ultimately mediate the proliferation and metastasis of HCC cells. SVEP1 could serve as a promising prognostic marker of HCC. MiR-1269b downregulates SVEP1 expression and promotes HCC proliferation and metastasis likely through the PI3k/Akt signaling pathway.

Synthesis and improved photochromic properties of pyrazolones in the solid state by incorporation of halogen.

Four novel photochromic pyrazolones have been prepared by introducing halogen atoms as substituents on the benzene ring. All as-synthesized compounds exhibited excellent reversible photochromic performances in the solid state. Upon UV light irradiation, the as-synthesized compounds can change their structures from E-form to K-form with yellow coloration. Further processed by heating, they rapidly reverted to their initial states at 120°Ð¡. Their photo-response and thermal bleaching kinetics were detailed investigated by UV absorption spectra. The results showed that the time constants were higher than that of our previously reported compounds at least one order of magnitude and the rate constants of the as-synthesized compounds were significantly influenced by the size and electronegativity of different halogen atoms. The fluorescence emission were modulated in a high degree via photoisomerization of pyrazolones, which might be due to the efficient energy transfer from E-form to K-form isomers for their partly overlaps between their E-form absorption spectra and K-form fluorescence spectra.

A novel anticancer agent Broussoflavonol B downregulates estrogen receptor (ER)-α36 expression and inhibits growth of ER-negative breast cancer MDA-MB-231 cells.

Estrogen receptor (ER)-negative breast cancers are aggressive and unresponsive to antiestrogens, and current therapeutic modalities for ER-negative breast cancer patients are usually associated with strong toxicity and side effects. Less toxic and more effective targeted therapies are urgently needed to treat this type of breast cancer. Here, we report that Broussoflavonol B, a chemical purified from the bark of the Paper Mulberry tree (Broussonetia papyrifera) exhibited potent growth inhibitory activity in ER-negative breast cancer MDA-MB-231 cells at sub-micromolar concentrations. Broussoflavonol B induced cell cycle arrest at both the G0/G1 and G2/M phases accompanied by a downregulation of c-Myc protein, a upregulation of the cell cycle inhibitory proteins p16(INK4a), p19(INK4D) and p21(WAF1/CIP1) and a down-regulation of the expression levels of the G2/M regulatory proteins such as cyclin B1, cdc2 and cdc25C. Broussoflavonol B also induced apoptotic cell death characterized by accumulation of the annexin V- and propidium iodide-positive cells, and cleavage of caspases 8, 9 and 3. In addition, Broussoflavonol B treatment also decreased the steady state levels of the epidermal growth factor receptor (EGFR) and ER-α36, a variant of estrogen receptor-α, and restricted growth of the stem-like cells in ER-negative breast cancer MDA-MB-231 cells. Our results thus indicate that Broussoflavonol B is a potent growth inhibitor for ER-negative breast cancer cells and provide a rational for preclinical and clinical evaluation of Broussoflavonol B for ER-negative breast cancer therapy.

Broussoflavonol B restricts growth of ER-negative breast cancer stem-like cells.

Accumulating experimental and clinical evidence has indicated that tumor-initiating or cancer stem-like cells are a sub-population of tumor cells capable of initiating and driving tumor growth, and cancer stem-like cells are resistant to most current cancer therapies, including chemo- and radiation therapy. More effective targeted-therapeutic approaches are urgently needed to eliminate cancer stem-like cells. Here, we report that broussoflavonol B, a chemical purified from the bark of the Paper Mulberry tree (broussonetia papyrifera), exhibited potent growth inhibitory activity towards estrogen receptor (ER)-negative breast cancer SK-BR-3 cells at sub-micromolar concentrations. Broussoflavonol B more potently inhibited growth and induced differentiation of stem-like SK-BR-3 cells-compared to the anti-estrogen tamoxifen. In addition, broussoflavonol B treatment also reduced the steady, state levels of the Human epidermal growth factor receptor-2 (HER2) and ER-α36, a variant of ER-α. Our results, thus, indicate that broussoflavonol B is a potent growth inhibitor of ER-negative breast cancer stem-like cells and provide a rationale for pre-clinical and clinical evaluation of broussoflavonol B for breast cancer therapy.