Newly Identified Cancer-Associated Role of Human Neuronal Growth Regulator 1 (NEGR1).

Neuronal growth regulator 1 (NEGR1) has become a great interest based on the recent findings that its genetic alteration is implicated in human obesity and human dyslexia. By analyzing the gene expression profiles of tumor biopsies and normal tissues, we identified NEGR1 as a commonly down-regulated gene in many types of human cancer tissues. NEGR1 contains a C-terminal GPI anchor attachment site and is primarily localized to cell membrane rafts, especially in cell-to-cell contacting areas. The oncogenic phenotype was clearly attenuated when NEGR1 was overexpressed in the human ovarian cancer cell line SKOV-3. Furthermore, cell aggregation and neurite outgrowth was greatly increased by NEGR1 overexpression. On the contrary, cell migration and invasion was increased in NEGR1-depleted cells, suggesting that NEGR1 may contribute to tumor suppression. Taken together, we suggest that NEGR1 is a raft-associated extracellular protein that may participate in cell recognition and interaction, which is important in growth control and malignant transformation.

Alendronate-loaded microparticles for improvement of intestinal cellular absorption.

This study examined a novel alendronate formulation that was developed to overcome the shortcomings of alendronate, such as its low bioavailability and gastric adverse effects. Alendronate microparticles were prepared using mucoadhesive polymers such as chitosan for improving the intestinal cellular absorption of alendronate and also using a gastric-resistant polymer such as Eudragit L100-55 for reducing the gastric inflammation of alendronate. Alendronate microparticles including chitosan showed a threefold increase in alendronate uptake (6.92 ± 0.27%) in Caco-2 cells when compared with the uptake of alendronate solution (2.38 ± 0.27%) into Caco-2 cells. Most interestingly, alendronate microparticles including chitosan showed 2.80 x 10⁻6 cm/s of an apparent permeability coefficient across Caco-2 cells and caused a significant 42.4% enhancement compared with that of alendronate solution across Caco-2 cells. The morphology of the Caco-2 cells treated with alendronate microparticles including chitosan was similar to that of the untreated cells and alendronate microparticles exhibited a negative effect to propodium iodide with some annexin-V fluorescence isothiocyante positive effect. It was proposed that the novel alendronate microparticles could possess the potential of an increased intestinal absorption and fewer adverse effects of alendronate.

Gene delivery using a derivative of the protein transduction domain peptide, K-Antp.

Due to their intracellular permeability, protein transduction domains (PTDs) have been widely used to deliver proteins and peptides to mammalian cells. However, their performance in gene delivery has been relatively poor. To improve the efficiency of PTD-mediated gene delivery, we synthesized a new peptide, KALA-Antp (K-Antp), which contains the sequences for PTD of the third alpha-helix of Antennapedia (Antp) homeodomain and the fusogenic peptide KALA. In this configuration, Antp is designed to provide the cell permeation capacity and nuclear localization signal, while the KALA moiety to promote cellular entry of the peptide-DNA complex. An optimal K-Antp/DNA formula was nearly 400-600 fold more efficient than Antp or poly-lysine-Antp (L-Antp) in gene delivery, and comparable or superior to a commercial liposome. The K-Antp-mediated plasmid DNA transfection not only exhibited temperature sensitivity, reflecting the involvement of an endocytosis-mediated gene transfer mechanism similar to other known PTDs, but also temperature insensitivity, suggesting the role of an energy-independent mechanism. Incorporation of an endosomolytic polymer polyethylenimine (PEI) into the system or treatment with chloroquine further increased the efficiency of K-Antp-mediated gene delivery. These results demonstrate the potential of the combinatorial use of KALA, Antp and PEI in the development of efficient PTD-derived gene carriers.

RNA-binding protein Csx1 is phosphorylated by LAMMER kinase, Lkh1, in response to oxidative stress in Schizosaccharomyces pombe.

Recent studies have shown that global gene expression during oxidative stress in Schizosaccharomyces pombe is regulated by stress-induced activation and binding of Csx1 to atf1(+) mRNA. However, the kinase responsible for the activation of Csx1 has not been identified. Here, we describe, for the first time, that Csx1 is phosphorylated by S. pombe LAMMER kinase, Lkh1, under oxidative conditions and that the stress-activated binding of the Csx1 to the atf1(+) mRNA was also affected by Lkh1 and Spc1. These data indicate that concerted actions of Spc1 and Lkh1 are required for the activation of Csx1 during oxidative condition in the fission yeast S. pombe.

Soluble forms of YlCrh1p and YlCrh2p, cell wall proteins of Yarrowia lipolytica, have beta-1,3-glycosidase activity.

Crh1p and Crh2p of Saccharomyces cerevisiae are cell wall proteins covalently attached to cell wall glucan and are thought to be putative glycosidases involved in cell wall remodelling. We investigated whether YlCrh1p and YlCrh2p, the Yarrowia lipolytica proteins homologous to ScCrh1p and ScCrh2p, had the required glycosidase activity for cell wall biosynthesis and maintenance. Ylcrh1Delta and Ylcrh2Delta mutants showed sensitivity to compounds that interfere with cell wall construction. Soluble forms of YlCrh1p and YlCrh2p that lacked the C-terminal consensus sequence for GPI anchoring showed glycosidase activity on laminarin, a substrate carrying beta-1,3-glycosidic linkage. Our study suggests that the YlCrh1p and YlCrh2p may participate in cell wall biosynthesis and remodelling through their beta-1,3-glycosidase activity.