Covalent stabilization of DNA nanostructures on cell membranes for efficient surface receptor-mediated labeling and function regulations

One major challenge of using DNA nanostructures for cellular and in vivo applications is their insufficiently structural integrity that stems from the non-covalent base pairing and stacking in complex cellular and physiological environment. The establishment of covalent bonds in DNA nanostructures can link individual strands more stably and therefore should improve the performance of DNA nanostructures in different scenarios where structural integrity is required. Here, we developed a convenient and effective method for constructing covalently stabilized DNA nanostructures by chemically inserting photo-crosslinker(^(CNV)K) in DNA sequences. These covalently linked DNA nanostructures were found to be more resistant to external interference, such as low cation concentrations and unspecific displacement on cell membranes. We also demonstrated that our strategy could improve the efficiency of cell surface receptor-mediated labeling and function regulations in living cells, which sheds light on broadening the biomedical applications of DNA nanostructures.

Applying a highly specific and reproducible cDNA RDA method to clone garlic up-regulated genes in human gastric cancer cells

AIM: To develop and optimize cDNA representational difference analysis (cDNA RDA) method and to identify and clone garlic up-regulated genes in human gastric cancer (HGC) cells. METHODS: We performed cDNA RDA method by using abundant double-stranded cDNA messages provided by two self-constructed cDNA libraries (Allitridi-treated and paternal HGC cell line BGC823 cells cDNA libraries respectively). Bam H I and Xho I restriction sites harbored in the library vector were used to select representations. Northern and Slot blots analyses were employed to identify the obtained difference products. RESULTS: Fragments released from the cDNA library vector after restriction endonuclease digestion acted as good marker indicating the appropriate digestion degree for library DNA. Two novel expressed sequence tags (ESTs) and a recombinant gene were obtained. Slot blots result showed a 8-fold increase of glia-derived nexin/protease nexin 1 (GDN/PN1) gene expression level and 4-fold increase of hepatitis B virus x-interacting protein (XIP) mRNA level in BGC823 cells after Allitridi treatment for 72h. CONCLUSION: Elevated levels of GDN/PN1 and XIP mRNAs induced by Allitridi provide valuable molecular evidence for elucidating the garlic's efficacies against neurodegenerative and inflammatory diseases. Isolation of a recombinant gene and two novel ESTs further show cDNA RDA based on cDNA libraries to be a powerful method with high specificity and reproducibility in cloning differentially expressed genes.

Lipopolysaccharide upregulates the expression of Toll-like receptor 4 in human vascular endothelial cells

OBJECTIVE: To investigate the expression of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) and the effect of lipopolysaccharide (LPS) on their expression in cultured endothelial cells. METHODS: Total RNA was extracted from ECV304 cells and isolated human umbilical vein endothelial cells (HUVECs) exposed to LPS, respectively. The quantification of TLR2 and TLR4 mRNA in HUVECs and EVC304 cells was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: ECV304 cells and HUVECs were able to express TLR2 and TLR4 mRNA, but the expression levels of TLR4 appeared to be stronger than those of TLR2. LPS could upregulate the expression levels of TLR4 obviously, whereas it had no effect on the expression level of TLR2. CONCLUSIONS: Our data indicate that TLR4 may be the LPS signal transducer in endothelial cells and plays important roles in the cell activation of LPS. The ECV304 cell line is a better experimental model than isolated HUVECs in the research of endothelial cells.

Clinical significance of plasma tissue factor pathway and urokinase-type plasminogen activator system in cancer patients

OBJECTIVE: To evaluate variations in the plasma tissue factor (TF) and urokinase type plasminogen activator (u-PA) system and their relationship with clinical cancer type, pathological classification and metastatic status in cancer patients. METHODS: Plasma levels of TF and its inhibitor (TFPI), as well as u-PA and its receptor (u-PAR) were measured using ELISA in 76 patients with malignant tumors and 24 patients with benign tumors. RESULTS: Plasma levels of TF and u-PAR in the malignant tumor group were significantly higher than those of the benign tumor group and the normal control. U-PA and u-PAR increased significantly in patients with esophageal and gastric cancer. However, most of these parameters except TFPI did not vary according to pathological classification. A significant elevation was evident in patients with local infiltration, lymph node involvement and distal metastasis, while u-PAR only increased in the latter two categories. CONCLUSIONS: Both the TF and u-PA systems are activated in cancer patients. U-PA and its receptor might prove to be a clinically useful marker for disease progression.

DNA Nanotechnology for Modulating the Growth and Development of Neurons

Late prenatal growth,early postnatal growth,and layering of the neocortical neurons(NC-Ns)play determining roles in the development of the cerebral cortex(CC).Here,we systematically explore the interactive role of neuronal surface receptors(NSRs)on cytoskeleton activation(CA)and the piconewton(pN)force generation(P-FG)and their influence on the proper development,growth,and functioning of neurons using a designed DNA nanomechanical device(DNA-NMD).