CpCAF1 from Chimonanthus praecox Promotes Flowering and Low-Temperature Tolerance When Expressed in Arabidopsis thaliana.

CCR4-associated factor I (CAF1) is a deadenylase that plays a critical role in the initial step of mRNA degradation in most eukaryotic cells, and in plant growth and development. Knowledge of CAF1 proteins in woody plants remains limited. Wintersweet (Chimonanthus praecox) is a highly ornamental woody plant. In this study, CpCAF1 was isolated from wintersweet. CpCAF1 belongs to the DEDDh (Asp-Glu-Asp-Asp-His) subfamily of the DEDD (Asp-Glu-Asp-Asp) nuclease family. The amino acid sequence showed highest similarity to the homologous gene of Arabidopsis thaliana. In transgenic Arabidopsis overexpressing CpCAF1, the timing of bolting, formation of the first rosette, and other growth stages were earlier than those of the wild-type plants. Root, lateral branch, rosette leaf, and silique growth were positively correlated with CpCAF1 expression. FLOWERING LOCUS T (FT) and SUPPRESSOROF OVEREXPRESSION OF CO 1 (SOC1) gene expression was higher while EARLY FLOWERING3 (ELF3) and FLOWERING LOCUS C (FLC) gene expression of transgenic Arabidopsis was lower than the wild type grown for 4 weeks. Plant growth and flowering occurrences were earlier in transgenic Arabidopsis overexpressing CpCAF1 than in the wild-type plants. The abundance of the CpCAF1 transcript grew steadily, and significantly exceeded the initial level under 4 °C in wintersweet after initially decreasing. After low-temperature exposure, transgenic Arabidopsis had higher proline content and stronger superoxide dismutase activity than the wild type, and the malondialdehyde level in transgenic Arabidopsis was decreased significantly by 12 h and then increased in low temperature, whereas it was directly increased in the wild type. A higher potassium ion flux in the root was detected in transgenic plants than in the wild type with potassium deficiency. The CpCAF1 promoter was a constitutive promoter that contained multiple cis-acting regulatory elements. The DRE, LTR, and MYB elements, which play important roles in response to low temperature, were identified in the CpCAF1 promoter. These findings indicate that CpCAF1 is involved in flowering and low-temperature tolerance in wintersweet, and provide a basis for future genetic and breeding research on wintersweet.

Siglec-15 as a New Perspective Therapy Target in Human Giant Cell Tumor of Bone.

The main features of a giant cell tumor of bone (GCTB) are frequent recurrence and aggressive osteolysis, which leads to a poor prognosis in patients. Although the treatment methods for a GCTB, such as scraping and resection, effectively inhibit the disease, the tendency toward malignant transformation remains. Therefore, it is important to identify new treatment methods for a GCTB. In this study, we first found high Siglec-15 expression in GCTB tissues, which was significantly associated with Campanacci staging and tumor recurrence. In Spearman's analysis, Siglec-15 expression was significantly correlated with Ki-67 levels in tumor tissues. In vitro, the mRNA and protein levels of Siglec-15 were high in GCTB stromal cells (Hs737. T), and Siglec-15 knockdown inhibited the biological characteristics of GCTB stromal cells. The RNA sequencing results enabled a prediction of the downstream genes by using the Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and MCODE analyses, and the findings showed that CXCL8 was significantly regulated by Siglec-15 and might be a promising downstream target gene of Siglec-15. Therefore, Siglec-15 may be a potential immunotherapy target for a GCTB.

Siglec-15 Promotes Tumor Progression in Osteosarcoma via DUSP1/MAPK Pathway.

Recurrence and metastasis are important features of osteosarcoma (OS) that cause its poor prognosis. Aberrant expression of Sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) has been reported in various kinds of cancers. However, the expression and function of Siglec-15 in OS remain unclear. In cultured OS cells (143B cells and MNNG/HOS cells) and their xenograft mouse models, we found that downregulation of Siglec-15 could inhibit the proliferation, migration and invasion of by inducing epithelial-mesenchymal transition (EMT) in vitro and in vivo. Conversely, Siglec-15 overexpression promoted the growth, migration and invasion of OS cells in a significant manner. Then, we screened a number of differentially expressed genes (DEGs) between Siglec-15-knockdown group and control group by RNA-Seq assay. Among these DEGs, we found that dual-specificity phosphatase 1 (DUSP1/MKP1) was significantly downregulated after Siglec-15 silencing. We investigated the DUSP1 functions in influencing OS cells' biology, and found that the proliferation, migration and invasion of OS cells were promoted by overexpressing DUSP1 and crucially, the proliferation, migration and invasion of Siglec-15-knockdown OS cells were rescued by overexpressing DUSP1. Mechanically, we further showed that DUSP1-mediated inhibition of p38/MAPK and JNK/MAPK expression was attenuated when Siglec-15 expression was inhibited, suggesting that Siglec-15 promotes the malignant progression of OS cells by suppressing DUSP1-mediated suppression of the MAPK pathway. Moreover, we showed that both Siglec-15 and DUSP1 were highly expressed in human OS tissues by immunohistochemistry. High Siglec-15 expression was associated with OS lung metastasis, and high DUSP1 expression was associated with the high Enneking stage. Kaplan-Meier analysis indicated that high expression of Siglec-15 could predict poor prognosis of OS patients. Altogether, these results showed that Siglec-15 expression promoted OS development and progression by activating DUSP1 and might be a novel target in OS treatment.

Clinical significance of serum soluble B7-H3 in patients with osteosarcoma.

BACKGROUND: Increasing data has indicated an association between increased soluble B7-H3 (sB7-H3) levels and unfavorable prognosis in patients with malignancies. However, the level of sB7-H3 and its clinical significance in osteosarcoma (OS) are not well known. In this present study, we investigated whether sB7-H3 levels in serum could be as a tool for differential diagnosis of OS patients. METHODS: Peripheral blood samples from healthy controls, benign bone tumors, and OS patients were collected. Levels of sB7-H3 in serum samples were measured by enzyme-linked immunosorbent assays. The correlation between OS-derived sB7-H3 and clinical features was analyzed, and prognostic significance of the sB7-H3 concentrations and tumor expressions of the biomarkers was then evaluated. RESULTS: sB7-H3 concentrations were significantly increased in patients with OS than in osteochondroma patients, bone fibrous dysplasia patients and healthy people (p < 0.05, respectively). Using 60.94 ng/mL as a cutoff value, the sensitivity and specificity of sB7-H3 was to differentiate between OS patients and other bone benign tumor patients were 75.7% and 83.8%, respectively. In addition, upregulated serum sB7-H3 in patients with OS associated with tumor differentiation, tumor stage, and metastasis status (p < 0.05, respectively). The area under the curve value for sB7-H3 (0.868) was markedly higher than those for ALP (0.713) and CA125 (0.789) for differentiating between OS patients and other begin bone tumor patients. CONCLUSIONS: We demonstrated that enhanced sB7-H3 levels correlated with the clinical characteristics of OS patients, and B7-H3 might be a potential biomarker and associated with the pathogenesis of OS.

D-glucosamine conjugation accelerates the labeling efficiency of quantum dots in osteoblastic cells.

Quantum dots (QDs) are useful imaging tools in the medical and biological fields due to their optical properties, such as a high fluorescence intensity, remarkable resistance to photobleaching, broad absorption spectra, and narrow emission spectra. This is the first study to investigate the uptake of carboxylated QDs conjugated with D-glucosamine (core size: approximately 3 nm, final modified size: 20-30 nm) into cultured osteoblastic cells. The QDs attached to the cell surface and were transported into the cytoplasm within approximately three hours of culture, whose process was clearly demonstrated using specific fluorescent staining of the cell membrane. Although the intranuclear distribution was not observed, a dramatic decrease in the transfer of quantum dots into the cytoplasm was recognized after approximately seven days of culture. Other interesting phenomena include the escape of the quantum dots from lysosomes in the cytoplasm, as confirmed by the merging of both QD fluorescence and specific fluorescent staining of lysosomes in the cytoplasm. These findings suggest that D-glucosamine conjugation enhances proton absorption in acid organelles and promotes the lysosomal escape of QDs.

Biological actions of green tea catechins on cardiac troponin C.

BACKGROUND AND PURPOSE: Catechins, biologically active polyphenols in green tea, are known to have a protective effect against cardiovascular diseases. In this study, we investigated direct actions of green tea catechins on cardiac muscle function to explore their uses as potential drugs for cardiac muscle disease. EXPERIMENTAL APPROACH: The effects of catechins were systematically investigated on the force-pCa relationship in skinned cardiac muscle fibres to determine their direct effects on cardiac myofilament contractility. The mechanisms of action of effective catechins were investigated using troponin exchange techniques, quartz crystal microbalance, nuclear magnetic resonance and a transgenic mouse model. KEY RESULTS: (-)-Epicatechin-3-gallate (ECg) and (-)-epigallocatechin-3-gallate (EGCg), but not their stereoismers (-)-catechin-3-gallate and (-)-gallocatechin-3-gallate, decreased cardiac myofilament Ca(2+) sensitivity probably through its interaction with cardiac troponin C. EGCg restored cardiac output in isolated working hearts by improving diastolic dysfunction caused by increased myofilament Ca(2+) sensitivity in a mouse model of hypertrophic cardiomyopathy. CONCLUSIONS AND IMPLICATIONS: The green tea catechins, ECg and EGCg, are Ca(2+) desensitizers acting through binding to cardiac troponin C. These compounds might be useful compounds for the development of therapeutic agents to treat the hypertrophic cardiomyopathy caused by increased Ca(2+) sensitivity of cardiac myofilaments.