The Power of Two: ARGININE 51 AND ARGININE 239* FROM A NEIGHBORING SUBUNIT ARE ESSENTIAL FOR CATALYSIS IN α-AMINO-β-CARBOXYMUCONATE-?-SEMIALDEHYDE DECARBOXYLASE*

Although the crystal structure of α-amino-β-carboxymuconate-ϵ-semialdehyde decarboxylase from Pseudomonas fluorescens was solved as a dimer, this enzyme is a mixture of monomer, dimer, and higher order structures in solution. In this work, we found that the dimeric state, not the monomeric state, is the functionally active form. Two conserved arginine residues are present in the active site: Arg-51 and an intruding Arg-239* from the neighboring subunit. In this study, they were each mutated to alanine and lysine, and all four mutants were catalytically inactive. The mutants were also incapable of accommodating pyridine-2,6-dicarboxylic acid, a competitive inhibitor of the native enzyme, suggesting that the two Arg residues are involved in substrate binding. It was also observed that the decarboxylase activity was partially recovered in a heterodimer hybridization experiment when inactive R51(A/K) and R239(A/K) mutants were mixed together. Of the 20 crystal structures obtained from mixing inactive R51A and R239A homodimers that diffracted to a resolution lower than 3.00 Å, two structures are clearly R51A/R239A heterodimers and belong to the C2 space group. They were refined to 1.80 and 2.00 Å resolutions, respectively. Four of the remaining crystals are apparently single mutants and belong to the P4₂2₁2 space group. In the heterodimer structures, one active site is shown to contain dual mutation of Ala-51 and Ala-239*, whereas the other contains the native Arg-51 and Arg-239* residues, identical to the wild-type structure. Thus, these observations provide the foundation for a molecular mechanism by which the oligomerization state of α-amino-β-carboxymuconate-ϵ-semialdehyde decarboxylase could regulate the enzyme activity.     

Flouride Promotes Viability and Differentiation of Osteoblast-Like Saos-2 Cells Via BMP/Smads Signaling Pathway

The BMP/Smad signaling pathway plays an important role in the viability and differentiation of osteoblast; however, it is not clear whether this pathway is involved in the fluoride-induced osteoblast differentiation. In this study, we investigated the role of BMP/Smad signaling pathway in fluoride-induced osteoblast-like Saos-2 cells differentiation. Cells were exposed to fluoride of different concentrations (0, 0.1, 0.2, 0.4, 0.8, and 1.6 mM), and cell proliferation was determined using WST assays. The expression of osteoblast marker genes such as osteocalcin (BGP) and bone alkaline phosphatase (BALP) were detected by qRT-PCR. We found that fluoride enhanced the proliferation of Saos-2 cells in a dose-dependent manner and 0.2 mM of fluoride resulted in a higher expression of osteoblast marker genes. In addition, immunofluorescence analysis showed that the promotion effects of 0.2 mM of fluoride on Saos-2 cells differentiation were associated with the activation of the BMP/Smad pathway. Expression of phosphorylated Smad1/5(p-Smad1/5) was higher in cells exposed to 0.2 mM of fluoride. Plasmid expression vectors encoding the short hairpin RNA (shRNA) targeting Smad4 gene were used to block the BMP/Smad pathway, which resulted in a significantly reduced expression of BGP and BALP as well as their corresponding mRNA. The mRNA levels after transfection remained low even in the presence of fluoride. The present results reveal that BMP/Smad signaling pathway was altered during the period of osteogenesis, and that the activities of p-Smad1/5 were required for Saos-2 cells viability and differentiation induced by fluoride.     

Disruption of inducible 6-phosphofructo-2-kinase impairs the suppressive effect of PPARγ activation on diet-induced intestine inflammatory response

PFKFB3 is a target gene of peroxisome proliferator-activated receptor gamma (PPARγ) and encodes for inducible 6-phosphofructo-2-kinase (iPFK2). As a key regulatory enzyme that stimulates glycolysis, PFKFB3/iPFK2 links adipocyte metabolic and inflammatory responses. Additionally, PFKFB3/iPFK2 is involved in the effect of active PPARγ on suppressing overnutrition-induced adipose tissue inflammatory response, which accounts for the insulin-sensitizing and antidiabetic effects of PPARγ activation. Using PFKFB3/iPFK2-disrupted mice, the present study investigated the role of PFKFB3/iPFK2 in regulating overnutrition-associated intestine inflammatory response and in mediating the effects of PPARγ activation. In wild-type mice, intestine PFKFB3/iPFK2 was increased in response to high-fat diet (HFD) feeding compared with that in mice fed a low-fat diet. However, intestine PFKFB3/iPFK2 was decreased in PFKFB3/iPFK2-disrupted mice and did not respond to HFD feeding. Furthermore, on an HFD, PFKFB3/iPFK2-disrupted mice displayed a significant increase in major intestine proinflammatory indicators such as toll-like receptor 4 expression, c-Jun N-terminal kinase 1 and nuclear factor kappa B phosphorylation, and proinflammatory cytokine expression compared with wild-type littermates. Upon treatment with rosiglitazone, an agonist of PPARγ, intestine proinflammatory indicators were markedly decreased in wild-type mice, but to a much lesser degree in PFKFB3/iPFK2-disrupted mice. Overall, the status of HFD-induced intestine inflammatory response in all treated mice correlated inversely with systemic insulin sensitivity, indicated by the homeostasis model assessment of insulin resistance data. Together, these results suggest that PFKFB3/iPFK2 is critically involved in the effect of PPARγ activation on suppressing diet-induced intestine inflammatory response.     

Repression of the Long Noncoding RNA-LET by Histone Deacetylase 3 Contributes to Hypoxia-Mediated Metastasis

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Highlights? There is low expression of lncRNA-LET in various tumor tissues ? Hypoxia-induced low expression of lncRNA-LET occurred through histone deacetylase 3 ? The lncRNA-LET is bound to NF90, which increases NF90 degradation by the proteasome ? Low lncRNA-LET expression contributes to hypoxia-induced cell invasion     

A genetic variant in pre-miR-27a is associated with a reduced breast cancer risk in younger Chinese population

Accumulating evidence has indicated that single nucleotide polymorphisms (SNPs) in miRNA precursors may have an effect on miRNA expression levels. Recently, an important A to G transition SNP in pre-mir-27a (rs895819) was identified. Previous studies have investigated the role of rs895819 in cancer risk, but the results remain contradictory, rather than conclusive. The present study aimed to evaluate the association of rs895819 with sporadic breast cancer susceptibility, clinicopathological characteristics and prognosis. We first analyzed the influence of rs895819 on the miR-27a expression level and determined that miR-27a expression was significantly lower in samples with the AG/GG genotype compared to samples with the AA genotype (p = 0.022). Further investigation revealed that subjects with the G allele exhibited a significantly decreased risk of breast cancer relative to subjects carrying the A allele among the younger population (adjusted OR = 0.628, 95% confidence interval 0.410–0.961; p = 0.032). Moreover, significant associations between the presence of rs895819 and the histological grade and estrogen status of breast cancers were observed among the older group. However, the SNP did not influence the survival rate of patients with breast cancer. In conclusion, our results suggest that the SNP rs895819 may serve as a risk factor for breast cancer in younger Chinese populations; however, larger population-based studies are needed to validate these findings.     

Long‐term ecological data for conservation: Range change in the black‐billed capercaillie (Tetrao urogalloides) in northeast China (1970s–2070s)

Long‐term ecological data can be an effective tool to help ecologists integrate future projections with historical contexts and provide unique insights into the long‐term dynamics of endangered species. However, hampered by data limitations, including incomplete and spatially biased data, relatively few studies have used multidecadal datasets or have examined changes in biogeography from a historical perspective. The black‐billed capercaillie (Tetrao urogalloides) is a large capercaillie (classified as Least Concern [LC] on the IUCN red list) that has undergone a dramatic decline in population during the late 20th century and is considered endangered. Its conservation status is pessimistic, and the species requires immediate protection. Therefore, we supplemented a historical dataset to identify changes in this bird's range and population in northeast China over the long term. The study area spanned Heilongjiang Province, Jilin Province, and the northeast corner of Inner Mongolia in northeast China. We integrated an ecological niche model (BIOMOD2) with long‐term ecological data on this species to estimate the magnitude of change in distribution over time. Our results revealed a 35.25% reduction in the current distribution of this species compared to their potential distribution in the 1970s. This decline is expected to continue under climate change. For example, the future range loss was estimated to be 38.79 ± 0.22% (8.64–90.19%), and the actual state could be worse, because the baseline range of the model was greater than the real range in the 2000s, showing a 12.39% overestimation. To overcome this poor outlook, a conservation strategy should be established in sensitive areas, including the southwestern Greater Khingan Mountains and northern Lesser Khingan Mountains. Actions that should be considered include field investigations, establishing a monitor network, designing ecological corridors, and cooperating with local inhabitants, governments, and conservation biologists to improve the conservation of the black‐billed capercaillie.     

MdATG18a overexpression improves tolerance to nitrogen deficiency and regulates anthocyanin accumulation through increased autophagy in transgenic apple

Nitrogen (N) availability is an essential factor for plant growth. Recycling and remobilization of N have strong impacts on crop yield and quality under N deficiency. Autophagy is a critical nutrient‐recycling process that facilitates remobilization under starvation. We previously showed that an important AuTophaGy (ATG) protein from apple, MdATG18a, has a positive role in drought tolerance. In this study, we explored its biological role in response to low‐N. Overexpression of MdATG18a in both Arabidopsis and apple improved tolerance to N‐depletion and caused a greater accumulation of anthocyanin. The increased anthocyanin concentration in transgenic apple was possibly due to up‐regulating flavonoid biosynthetic and regulatory genes (MdCHI, MdCHS, MdANS, MdPAL, MdUFGT, and MdMYB1) and higher soluble sugars concentration. MdATG18a overexpression enhanced starch degradation with up‐regulating amylase gene (MdAM1) and up‐regulated sugar metabolism related genes (MdSS1, MdHXKs, MdFK1, and MdNINVs). Furthermore, MdATG18a functioned in nitrate uptake and assimilation by up‐regulating nitrate reductase MdNIA2 and 3 high‐affinity nitrate transporters MdNRT2.1/2.4/2.5. MdATG18a overexpression also elevated other important MdATG genes expression and autophagosomes formation under N‐depletion, which play key contributions to above changes. Together, these results demonstrate that overexpression of MdATG18a enhances tolerance to N‐deficiencies and plays positive roles in anthocyanin biosynthesis through greater autophagic activity.     

In vitro induction of allohexaploid and resulting phenotypic variation in <Emphasis Type="Italic">Populus</Emphasis>

Although triploid Populus varieties have been used widely in timber and pulpwood production, the performance of economic traits in Populus with higher ploidy levels remains unknown due to a lack of germplasms with higher ploidy. In this study, we first successfully induced hexaploids in Populus by treating triploid leaf explants with colchicine in vitro. In total, 32 hexaploids were produced. The frequency of hexaploids was significantly affected by the interaction between colchicine concentration and exposure time. The highest hexaploid induction efficiency was 16.89% (±?2.26), which was achieved by treating explants with 0.04% colchicine for 7 days. Compared to triploids, hexaploids had thinner epidermal hair, larger stomata and protoplasts, and fewer chloroplasts, indicating that significant phenotypic changes accompanied an increase in ploidy level. These hexaploids are valuable for investigating the performance of economic traits in Populus with higher ploidy levels and have the potential to be used as parents to produce new tetraploid and pentaploid germplasms in Populus breeding programs.     

Prevalence and in-hospital outcomes of diabetes among patients with acute coronary syndrome in China: findings from the Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome Project

Background

Guidelines have classified patients with acute coronary syndrome (ACS) and diabetes as a special population, with specific sections presented for the management of these patients considering their extremely high risk. However, in China up-to-date information is lacking regarding the burden of diabetes in patients with ACS and the potential impact of diabetes status on the in-hospital outcomes of these patients. This study aims to provide updated estimation for the burden of diabetes in patients with ACS in China and to evaluate whether diabetes is still associated with excess risks of early mortality and major adverse cardiovascular and cerebrovascular events (MACCE) for ACS patients.

Methods

The Improving Care for Cardiovascular Disease in China-ACS Project was a collaborative study of the American Heart Association and the Chinese Society of Cardiology. A total of 63,450 inpatients with a definitive diagnosis of ACS were included. Prevalence of diabetes was evaluated in the overall study population and subgroups. Multivariate logistic regression was performed to examine the association between diabetes and in-hospital outcomes, and a propensity-score-matched analysis was further conducted.

Results

Among these ACS patients, 23,880 (37.6%) had diabetes/possible diabetes. Both STEMI and NSTE-ACS patients had a high prevalence of diabetes/possible diabetes (36.8% versus 39.0%). The prevalence of diabetes/possible diabetes was higher in women (45.0% versus 35.2%, p?<?0.001). Even in patients younger than 45 years, 26.9% had diabetes/possible diabetes. While receiving comparable treatments for ACS, diabetes/possible diabetes was associated with a twofold higher risk of all-cause death (adjusted odds ratio 2.04 [95% confidence interval 1.78–2.33]) and a 1.5-fold higher risk of MACCE (adjusted odds ratio 1.54 [95% confidence interval 1.39–1.72]).

Conclusions

Diabetes was highly prevalent in patients with ACS in China. Considerable excess risks for early mortality and major adverse cardiovascular events were found in these patients.Trial registration NCT02306616. Registered December 3, 2014