Transition from horizontal expansion to vertical growth in the oyster prismatic layer.

Biomimetic materials inspired by biominerals have substantial applications in various fields. The prismatic layer of bivalve molluscs has extraordinary flexibility compared to inorganic CaCO3. Previous studies showed that in the early stage, minerals expanded horizontally and formed prism domains as a Voronoi division, while the evolution of the mature prisms were thermodynamically driven, which was similar to grain growth. However, it was unclear how the two processes were correlated during shell formation. In this study, we used scanning electronic microscopy and laser confocal scanning microscopy to look into the microstructure of the columnar prismatic layer in the pearl oyster Pinctada fucata. The Dirichlet centers of the growing domains in mature prisms were calculated, and the corresponding Voronoi division was reconstructed. It was found that the domain pattern did not fit the Voronoi division, indicating the driving forces of the mature prisms evolution and the initiation stage were different. During the transition from horizontal expansion to vertical growth, the minerals broke through the inner periostracum and squeezed out the organic materials to the inter-prism space. Re-arrangement of the organic framework pattern was driven by elastic relaxation at the vertices, indicating the transition process was thermodynamically driven. Our study provided insights into shell growth in bivalves and pave the way to synthesize three-dimensional material biomimetically.

Hsp90α forms a stable complex at the cilium neck for the interaction of signalling molecules in IGF-1 receptor signalling.

The primary cilium is composed of an axoneme that protrudes from the cell surface, a basal body beneath the membrane and a transition neck in between. It is a sensory organelle on the plasma membrane, involved in mediating extracellular signals. In the transition neck region of the cilium, the microtubules change from triplet to doublet microtubules. This region also contains the transition fibres that crosslink the axoneme with the membrane and the necklace proteins that regulate molecules being transported into and out of the cilium. In this protein-enriched, complex area it is important to maintain the correct assembly of all of these proteins. Here, through immunofluorescent staining and protein isolation, we identify the molecular chaperone Hsp90α clustered at the periciliary base. At the transition neck region, phosphorylated Hsp90α forms a stable ring around the axoneme. Heat shock treatment causes Hsp90α to dissipate and induces resorption of cilia. We further identify that Hsp90α at the transition neck region represents a signalling platform on which IRS-1 interacts with intracellular downstream signalling molecules involved in IGF-1 receptor signalling.

A novel acidic matrix protein, PfN44, stabilizes magnesium calcite to inhibit the crystallization of aragonite.

Magnesium is widely used to control calcium carbonate deposition in the shell of pearl oysters. Matrix proteins in the shell are responsible for nucleation and growth of calcium carbonate crystals. However, there is no direct evidence supporting a connection between matrix proteins and magnesium. Here, we identified a novel acidic matrix protein named PfN44 that affected aragonite formation in the shell of the pearl oyster Pinctada fucata. Using immunogold labeling assays, we found PfN44 in both the nacreous and prismatic layers. In shell repair, PfN44 was repressed, whereas other matrix proteins were up-regulated. Disturbing the function of PfN44 by RNAi led to the deposition of porous nacreous tablets with overgrowth of crystals in the nacreous layer. By in vitro circular dichroism spectra and fluorescence quenching, we found that PfN44 bound to both calcium and magnesium with a stronger affinity for magnesium. During in vitro calcium carbonate crystallization and calcification of amorphous calcium carbonate, PfN44 regulated the magnesium content of crystalline carbonate polymorphs and stabilized magnesium calcite to inhibit aragonite deposition. Taken together, our results suggested that by stabilizing magnesium calcite to inhibit aragonite deposition, PfN44 participated in P. fucata shell formation. These observations extend our understanding of the connections between matrix proteins and magnesium.

The N-terminal leucine-zipper motif in PTRF/cavin-1 is essential and sufficient for its caveolae-association.

PTRF/cavin-1 is a protein of two lives. Its reported functions in ribosomal RNA synthesis and in caveolae formation happen in two different cellular locations: nucleus vs. plasma membrane. Here, we identified that the N-terminal leucine-zipper motif in PTRF/cavin-1 was essential for the protein to be associated with caveolae in plasma membrane. It could counteract the effect of nuclear localization sequence in the molecule (AA 235-251). Deletion of this leucine-zipper motif from PTRF/cavin-1 caused the mutant to be exclusively localized in nuclei. The fusion of this leucine-zipper motif with histone 2A, which is a nuclear protein, could induce the fusion protein to be exported from nucleus. Cell migration was greatly inhibited in PTRF/cavin-1(-/-) mouse embryonic fibroblasts (MEFs). The inhibited cell motility could only be rescued by exogenous cavin-1 but not the leucine-zipper motif deleted cavin-1 mutant. Plasma membrane dynamics is an important factor in cell motility control. Our results suggested that the membrane dynamics in cell migration is affected by caveolae associated PTRF/cavin-1.

Structural characterization of amorphous calcium carbonate-binding protein: an insight into the mechanism of amorphous calcium carbonate formation.

ACC (amorphous calcium carbonate) plays an important role in biomineralization process for its function as a precursor for calcium carbonate biominerals. However, it is unclear how biomacromolecules regulate the formation of ACC precursor in vivo. In the present study, we used biochemical experiments coupled with bioinformatics approaches to explore the mechanisms of ACC formation controlled by ACCBP (ACC-binding protein). Size-exclusion chromatography, chemical cross-linking experiments and negative staining electron microscopy reveal that ACCBP is a decamer composed of two adjacent pentamers. Sequence analyses and fluorescence quenching results indicate that ACCBP contains two Ca²âº-binding sites. The results of in vitro crystallization experiments suggest that one Ca²âº-binding site is critical for ACC formation and the other site affects the ACC induction efficiency. Homology modelling demonstrates that the Ca²âº-binding sites of pentameric ACCBP are arranged in a 5-fold symmetry, which is the structural basis for ACC formation. To the best of our knowledge, this is the first report on the structural basis for protein-induced ACC formation and it will significantly improve our understanding of the amorphous precursor pathway.

Novel basic protein, PfN23, functions as key macromolecule during nacre formation.

The fine microstructure of nacre (mother of pearl) illustrates the beauty of nature. Proteins found in nacre were believed to be "natural hands" that control nacre formation. In the classical view of nacre formation, nucleation of the main minerals, calcium carbonate, is induced on and by the acidic proteins in nacre. However, the basic proteins were not expected to be components of nacre. Here, we reported that a novel basic protein, PfN23, was a key accelerator in the control over crystal growth in nacre. The expression profile, in situ immunostaining, and in vitro immunodetection assays showed that PfN23 was localized within calcium carbonate crystals in the nacre. Knocking down the expression of PfN23 in adults via double-stranded RNA injection led to a disordered nacre surface in adults. Blocking the translation of PfN23 in embryos using morpholino oligomers led to the arrest of larval development. The in vitro crystallization assay showed that PfN23 increases the rate of calcium carbonate deposition and induced the formation of aragonite crystals with characteristics close to nacre. In addition, we constructed the peptides and truncations of different regions of this protein and found that the positively charged C-terminal region was a key region for the function of PfN23 Taken together, the basic protein PfN23 may be a key accelerator in the control of crystal growth in nacre. This provides a valuable balance to the classic view that acidic proteins control calcium carbonate deposition in nacre.

The role of matrix proteins in the control of nacreous layer deposition during pearl formation.

To study the function of pearl oyster matrix proteins in nacreous layer biomineralization in vivo, we examined the deposition on pearl nuclei and the expression of matrix protein genes in the pearl sac during the early stage of pearl formation. We found that the process of pearl formation involves two consecutive stages: (i) irregular calcium carbonate (CaCO(3)) deposition on the bare nucleus and (ii) CaCO(3) deposition that becomes more and more regular until the mature nacreous layer has formed on the nucleus. The low-expression level of matrix proteins in the pearl sac during periods of irregular CaCO(3) deposition suggests that deposition may not be controlled by the organic matrix during this stage of the process. However, significant expression of matrix proteins in the pearl sac was detected by day 30-35 after implantation. On day 30, a thin layer of CaCO(3), which we believe was amorphous CaCO(3), covered large aragonites. By day 35, the nacreous layer had formed. The whole process is similar to that observed in shells, and the temporal expression of matrix protein genes indicated that their bioactivities were crucial for pearl development. Matrix proteins controlled the crystal phase, shape, size, nucleation and aggregation of CaCO(3) crystals.

Improved synthesis of 2'-deoxyadenosine and 5-methyluridine by Escherichia coli using an auto-induction system.

Nucleoside analogues are used widely for the treatment of viral diseases and cancer, however the preparation of some important intermediates of these nucleoside analogues, including 2'-deoxyadenosine (dAR) and 5-methyluridine (5-MU), remains inconvenient. To optimize the synthesis of dAR and 5-MU, recombinant strains and auto-induction medium were employed in this study. E. coli BL21(DE3) strains overexpressing purine nucleoside phosphorylase (PNP), uridine phosphorylase (UP) and thymidine phosphorylase (TP) were constructed and cultured in auto-induction ZYM-Fe-5052 medium for 8 h. The cultures of these strains were then used directly to synthesize dAR and 5-MU. Under optimized conditions, 30 mM adenine was converted to 29 mM dAR in 1 h, and 32 mM 5-MU was obtained from 60 mM thymine, using 6% (v/v) cell solutions as biocatalysts. These results indicate that our convenient and efficient method is ideal for the preparation of dAR and 5-MU, and has potential for the preparation of other nucleoside analogue intermediates.

Transformation of prednisolone to a 20ß-hydroxy prednisolone compound by Streptomyces roseochromogenes TS79.

Prednisolone represents an important compound in pharmaceutical preparations. To obtain more bioactive prednisolone derivatives, the microbial transformation of prednisolone was carried out. The steroid products were assigned by an interpretation of their spectral data using mass spectrometry and proton nuclear magnetic resonance ((1)H NMR) analyses. The product was assigned the chemical structure of 11ß, 17α, 20ß, 21-tetrahydroxypregna-1,4-diene-3-one (named as 20ß-hydroxy prednisolone). The conversion of prednisolone to 20ß-hydroxy prednisolone by Streptomyces roseochromogenes TS79 was different from a previous study on the microbial transformation of steroid by this organism, which usually generates a 16α-hydroxy steroid product. The different reaction parameters for maximum conversion of prednisolone were optimized. The analysis revealed that the optimum values of the tested variables were 7.5 mg/ml prednisolone dissolved in DMSO and added to the 24-h pre-culture fermentation culture containing 0.05% MgSO(4) and incubated for 24 h. A conversion of 95.1% of prednisolone was observed, which has the potential to be used in industrial production.

Calcineurin mediates the immune response of hemocytes through NF-kappaB signaling pathway in pearl oyster (Pinctada fucata).

Calcineurin (CN), a multifunctional protein, mediates the immune response through diverse signaling pathways in mammals, while the function of CN in the immune response of molluscan hemocytes still remains unclear. In the present study, we detected the distribution of CN in various tissues and the expression levels of Pf-CNA and Pf-CNB gene in hemocytes of Pinctada fucata. After the preparation of hemocyte monolayers, we checked the response of enzymatic activity of CN, the degradation level of IkappaBalpha, the activity of iNOS and the production of NO, and IL-2 to the challenge of lipopolysaccharide (LPS) and cyclosporin A (CsA). CN activity in hemocytes was very sensitive to both the stimulation of LPS and the inhibition of CsA. Most importantly, IkappaBalpha degradation in hemocytes was induced by LPS and attenuated by CsA. Consequently, the activity of iNOS was elevated and the production of NO was increased. Additionally, we found that the synthesis of IL-2 was increased by LPS but was apparently weakened by CsA. In vivo bacterial clearance experiments showed that CsA significantly decreased the ability of in vivo bacteria clearance in pearl oyster. All the results revealed, for the first time, that CN mediated the immune response of molluscan hemocytes via activating NF-kappaB signaling pathway.

MicroRNA-224 is upregulated in HepG2 cells and involved in cellular migration and invasion.

BACKGROUND AND AIM: MicroRNAs are a class of small non-coding RNAs that negatively regulate the expression of their target genes. The aim of the present study was to explore the effects of microRNA on biological behaviors of HepG2 cells and further analyze its characteristics. METHODS: We detected different expression profiles of miRNAs in HepG2 and L02 cell lines by microRNA microarray. Northern blot, quantitative real-time polymerase chain reaction, methylthiazolyl tetrazolium, fluorescence-activated cell sorting, scratch wound, transwell migration and Matrigel invasion assays and western blot were carried out to determine whether or not microRNA-224 (miR-224) can influence the biological behaviors of HepG2 cells. RESULTS: MiR-224 was significantly upregulated in HepG2 cells. Cell proliferation, migration and invasion, but not cell cycles, were altered after changing the expression of miR-224. Taking invasion and migration as a breakthrough, a close relationship between the expression of miR-224 and its proteins such as PAK4 and MMP9, which were involved in the invasion of tumor, was found. CONCLUSIONS: Overexpression of miR-224 was involved in the malignant phenotype of HepG2 cells, and it may be an important factor in regulating the migration and invasion of HepG2 cells.

Cyclodextrin Porous Liquid Materials for Efficient Chiral Recognition and Separation of Nucleosides.

Porous liquids are porous materials that have exhibited unique properties in various fields. Herein, we developed a method to synthesize the type I porous liquids via liquefaction of cyclodextrins by chemical modification. The cyclodextrin porous liquids were characterized by Fourier-transform infrared (FTIR) spectroscopy, NMR, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), circular dichroism (CD), and UV-vis spectroscopy. The measured ionic conductivity of the γ-cyclodextrin porous liquid was 500 times as great as that of its reactants, which was found to be the first instance with such great conductivity for a type I porous liquid. What is more, the γ-cyclodextrin porous liquid had been demonstrated experimentally to have outstanding chiral recognition ability toward pyrimidine nucleosides in water, which was further confirmed by computational simulations. Additionally, enantiomeric excess of the extracted nucleoside was achieved up to 84.81% by convenient extraction from the mixture of racemic nucleosides and γ-cyclodextrin porous liquid. The great features of the novel cyclodextrin porous liquids could bring opportunities in many fields, including the preparation of chiral separation materials, development of new drug screening mechanisms, and construction of chiral response materials.

Eradication of tumor growth by delivering novel photothermal selenium-coated tellurium nanoheterojunctions.

Two-dimensional nanomaterial-based photothermal therapy (PTT) is currently under intensive investigation as a promising approach toward curative cancer treatment. However, high toxicity, moderate efficacy, and low uniformity in shape remain critical unresolved issues that hamper their clinical application. Thus, there is an urgent need for developing versatile nanomaterials to meet clinical expectations. To achieve this goal, we developed a stable, highly uniform in size, and nontoxic nanomaterials made of tellurium-selenium (TeSe)-based lateral heterojunction. Systemic delivery of TeSe nanoparticles in mice showed highly specific accumulation in tumors relative to other healthy tissues. Upon exposure to light, TeSe nanoparticles nearly completely eradicated lung cancer and hepatocellular carcinoma in preclinical models. Consistent with tumor suppression, PTT altered the tumor microenvironment and induced immense cancer cell apoptosis. Together, our findings demonstrate an exciting and promising PTT-based approach for cancer eradication.

Prodrug-Loaded Zirconium Carbide Nanosheets as a Novel Biophotonic Nanoplatform for Effective Treatment of Cancer.

Conventional chemotherapy and photothermal therapy (PTT) face many major challenges, including systemic toxicity, low bioavailability, ineffective tissue penetration, chemotherapy/hyperthermia-induced inflammation, and tumor angiogenesis. A versatile nanomedicine offers an exciting opportunity to circumvent the abovementioned limitations for their successful translation into clinical practice. Here, a promising biophotonic nanoplatform is developed based on the zirconium carbide (ZrC) nanosheet as a deep PTT-photosensitizer and on-demand designed anticancer prodrug SN38-Nif, which is released and activated by photothermia and tumor-overexpressed esterase. In vitro and in vivo experimental evidence shows the potent anticancer effects of the integrated ZrC@prodrug biophotonic nanoplatform by specifically targeting malignant cells, chemotherapy/hyperthermia-induced tumor inflammation, and angiogenesis. In mouse models, the ZrC@prodrug system markedly inhibits tumor recurrence, metastasis, inflammation and angiogenesis. The findings unravel a promising biophotonic strategy for precision treatment of cancer.

Reactive oxygen species production and Bax/Bcl-2 regulation in honokiol-induced apoptosis in human hepatocellular carcinoma SMMC-7721 cells.

We investigated possible mechanism(s) where honokiol induces apoptosis in human hepatocellular carcinoma SMMC-7721 cells. MTT assay showed that honokiol has strong inhibition on SMMC-7721 cells in a dose-dependent manner. SMMC-7721 cells after honokiol treatment display morphological characteristics such as cell shrinkage, detachment from the culture plate, formation of apoptotic bodies, change to a round shape, and marked nuclear condensation and fragmentation after 32258 staining. Cell apoptosis was measured by Annexin-V/PI staining and alternatively, by the subG0/G1 percentage of the cell cycle analysis followed by FACS. An obvious loss of ΔΨ(m) and a quick burst of ROS was detected when honokiol reached 4µg/ml, which was coincident with the high apoptosis percentage in our previous research. Up-regulation of Bax and down-regulation of Bcl-2 were observed, suggesting that honokiol-induced apoptosis was associated with reactive oxygen species (ROS) production and an increase of Bax/Bcl-2 ratios.

The RNA helicase DHX33 is required for cancer cell proliferation in human glioblastoma and confers resistance to PI3K/mTOR inhibition.

Human Glioblastoma is one deadly disease; the median survival time is reported to be 13.9 months after treatment. In the present study, we discovered that DHX33 is highly expressed in 84% of all Glioblastoma multiforme (GBM). Knockdown of DHX33 led to significant reduced proliferation and migration in glioblastoma cells in vitro and in vivo. Mechanistically, DHX33 regulated a set of critical genes involved in cell cycle and cell migration to promote glioblastoma development. Additionally, DHX33 was found to be induced by inhibitors of PI3K and mTOR whose activation has been detected in 50% of glioblastoma. Overexpression of wild type DHX33 protein, but not the helicase dead mutant, confers resistance to mTOR inhibitors in glioblastoma cells. DHX33 probably functions as a critical regulator to promote GBM development. Our results highlight its therapeutic potential in treating GBM.

Establishment of a high throughput-screening system for nucleoside deoxyribosyltransferase II mutant enzymes with altered substrate specificity.

Nucleoside deoxyribosyltransferase II (NDT) catalyzes the transglycosylation reaction of the 2'-deoxyribose moiety between purine and/or pyrimidine bases and has been widely used in the synthesis of nucleoside analogs. The high specificity of NDT for 2'-deoxyribose limits its applications. Because 2'C- and/or 3'C-modified nucleosides have been widely used as antiviral or antitumour agents, improving the activity of NDT towards these modified nucleosides by protein engineering is an area of interest to the pharmaceutical industry. NDT engineering is hindered by a lack of effective screening methods. This study developed a high-throughput screening system, which was established by nucleoside deoxyribosyltransferase II-cytidine deaminase co-expression, indophenol colorimetric assay and whole-cell catalysis. A high-throughput screening system for NDT was established for the first time. This system can be applied to detect NDT-specific activity for a variety of cytidine analogs with glycosyl and base modifications, such as 5-aza-2'-deoxycytidine, 2',3'-dideoxycytidine, cytosine-ß-d-arabinofuranoside. In this study, we adopted the semi-rational design of NDT and constructed a mutant library of NDT from Lactobacillus helveticus (LhNDT) by site-saturation mutagenesis. Over 600 mutants were screened, and a variant with up to a 5.2-fold higher conversion rate of 2',3'-dideoxyinosine was obtained.

Fluorescent conjugated polyelectrolyte as an indicator for convenient detection of DNA methylation.

A convenient, sensitive, and label-free method to determine the DNA methylation status of CpG sites of plasmid and human colon cancer cell has been developed. The system relies on highly selective single base extension reaction and significant optical amplification of cationic conjugated polyelectrolytes (CCP-1). The higher fluorescence resonance energy transfer efficiency between CCP-1 and fluorescein-labeled dGTP (dGTP-Fl) is correlated to the incorporation of dGTP-Fl into the probe DNA by single base extension reaction when the target/probe pair is complementary at the methylation site. As low as 1% methylation status can be determined by this new assay method. Because of the optical amplification property of CCP-1, the method exhibited high sensitivity with a concentration of analyte DNA at the picomolar level. The CCP-1 can form a complex with negatively charged DNA through electrostatic interactions, avoiding labeling the DNA target and probe by covalent linking. The isolation steps employed in other typical assays were avoided to simplify operations and increase repeatability. These features make the system promising for future use for early cancer diagnosis.

The inner-shell film: an immediate structure participating in pearl oyster shell formation.

In mollusks, the inner shell film is located in the shell-mantle zone and it is important in shell formation. In this study, we found that the film was composed of two individual films under certain states and some columnar structures were observed between the two individual films. The inner shell film was separated with the process of ethylenediaminetetraacetic acid (EDTA) treatment and the film proteins were extracted. Amino acid analysis showed that the film proteins may consist of shell framework proteins. The calcite crystallization experiment showed that the film proteins could inhibit the growth of calcite, while the CaCO(3) precipitation experiment showed that the film proteins could accelerate the rate of CaCO(3) precipitation. All these results suggested that the film plays an important role in shell formation. It may facilitate the aragonite formation by inhibiting the growth of calcite and accelerate the shell growth by promoting the precipitation of CaCO(3) crystals.

Effects of oridonin on proliferation of HT29 human colon carcinoma cell lines both in vitro and in vivo in mice.

Oridonin, an active ditepenoid component isolated from Rabdosia rubescens which is currently one of the most important Chinese traditional herbs, has been reported to exhibit anti-tumor effects in vitro. In this study, the anti-proliferation effect of oridonin against the human colorectal carcinoma cells HT29 was investigated both in vitro and in vivo. MTT assay showed that oridonin inhibited HT29 cells in a time- and dose-dependent manner. Flow cytometric analysis demonstrated that oridonin induced a G2/M phase arrest. Apoptotic bodies were observed by Hoechst 32258 fluorescence staining. Notable apoptosis and decrease of mitochondrial membrane potentials was also detected by flow cytometry. In the in vivo experiments, oridonin (10, 15, 20 mg kg(-1) of body weight, on days 1-12) was injected intraperitoneally into mice 24 h after the mice were incubated with HT29 cells. Inhibition of the solid tumor was observed. As a result, oridonin could inhibit the proliferation of HT29 cells both in vitro and in vivo, and induce apoptosis partly via the mitochondrial pathway.