Effect of IL-12 encoding plasmid administration on tight-skin mouse

The tight-skin (Tsk/+) mutant mice, a putative murine model of scleroderma, are characterized by the excessive deposition of collagen and the presence of antinuclear antibodies. Type 2 cytokines, such as IL-4 and IL-6, are capable of regulating the synthesis of various matrix molecules, including type I collagen, by fibroblasts. IL-12 is well known to induce type 1 cytokine production and to reduce type 2 activity. Here, we examined the effect of IL-12 encoding plasmid (pCAGGSIL-12) on the disease progression of Tsk/+ mice. pCAGGSIL-12 plasmid or pCAGGS parental vector was injected intramuscularly 7 times at 3 week intervals into Tsk/+ mice. One week after the last injection, pCAGGSIL-12 administered Tsk/+ mice exhibited a marked decrease in the skin thickness compared with the mice treated with pCAGGS vector. The serum levels of antinuclear antibodies were diminished in pCAGGSIL-12 treated mice. IL-4 production by spleen cells from pCAGGSIL-12 plasmid treated mice was significantly lower than that from vector treated mice. These results indicate that pCAGGSIL-12 administration into Tsk/+ mice had beneficial effects in preventing the collagen accumulation in the skin and suppressing the autoimmunity via improvement of Th1/Th2 balance. The present study suggests that the IL-12 encoding plasmid administration might have a therapeutic effect on systemic sclerosis.     

cGMP-dependent protein kinase phosphorylates and inactivates RhoA

Small GTPase Rho and cGMP/cGMP-dependent protein kinase (cGK) pathways exert opposing effects in specific systems such as vascular contraction and growth. However, the direct interaction between these pathways has remained elusive. We demonstrate that cGK phosphorylates RhoA in vitro at Ser188, the same residue phosphorylated by cAMP-dependent protein kinase. In HeLa cells transfected with constitutively active cGK (C-cGK), stress fiber formation induced by lysophosphatidic acid or V14RhoA was blocked. By contrast, C-cGK failed to inhibit stress fiber formation in cells transfected with mutant RhoA with substitution of Ser188 to Ala. C-cGK did not affect actin reorganization induced by Rac1 or Rho-associated kinase, one of the effectors for RhoA. Furthermore, C-cGK expression inhibited the membrane translocation of RhoA. Collectively, our findings suggest that cGK phosphorylates RhoA at Ser188 and inactivates RhoA signaling. The physiological relevance of the direct interaction between RhoA and cGK awaits further investigation.     

Systematic search for single nucleotide polymorphisms in the insulin gene: evidence for a high frequency of -23T-->A in Japanese subjects

It has recently been shown that the A/A genotype at g.-23 of the insulin gene correlates with impaired insulin secretion in response to body weight gain in subjects of European descent. To examine whether there are single nucleotide polymorphisms (SNPs) in the insulin gene associated with type 2 diabetes, all exons with their flanking sequences for 113 Japanese type 2 diabetic patients and 99 nondiabetic control subjects were analyzed using PCR direct sequencing. We have only found g.-23T --> A, 806G --> C, 1128T --> C, and 1141A --> C, which have previously been reported in alpha (A-C-C-C) and beta (T-G-T-A) alleles. The allele frequency of -23T --> A in control Japanese subjects was 97.4%, whereas that in Europeans is about 30%. The A/A genotype was found in 94 of 99 Japanese subjects (94.9%) and the allele frequencies of 806G --> C, 1128T --> C, and 1141A --> C were all 96.5%. The estimated haplotype frequencies were (A-C-C-C) (96.0%), (T-G-T-A) (2.0%), (A-G-T-A) (1.5%), and (T-C-C-C) (0.5%). No association of these SNPs or haplotypes with type 2 diabetes was evident. Thus, the A/A genotype at the g.-23 of insulin gene was generally high in Japanese subjects, which could account for the fact that they typically secrete lower levels of insulin.     

Aerosolization of cationic lipid-DNA complexes: lipoplex characterization and optimization of aerosol delivery conditions

This study deals with the development of gene therapy in the treatment of lung diseases. It reports on the use of ultrasonic nebulization to administer plasmid-lipid complexes to the lungs of mice to transfect their epithelial cells. A plasmid complexed to cationic lipids was aerosolized using an ultrasonic nebulizer. We then characterized the lipoplex size and visualized the lipoplex by electron microscopy. Finally, we assessed the in vivo transgene expression in the lungs further to the aerosolization of different lipid-plasmid formulations. The nebulizer-generated particles were small and looked like a string composed of little and more or less cubic units. Transgene expression was detected in the lungs of mice further to a 20-min exposure to aerosol particles produced with the ultrasonic nebulizer. The results obtained with our optimized plasmid-lipid-NaCl formulation suggest that this route can be used to administer an appropriate gene to the airways for the treatment of respiratory disorders.     

Identification of active regions for neurite outgrowth activity of neurocrescin

We previously identified and cloned a neurite outgrowth promoting protein, Neurocrescin (NC), from the extract of the chick denervated leg muscles. In this study, we explored the active region of NC for neurite outgrowth. Using the deletion mutants of NC, we tested their neurite outgrowth activity in the cultured telencephalic neurons of E5 chick embryos. We found three regions which independently had significant neurite outgrowth activity comparable with that of the extract of the chick denervated leg muscles. These regions were not homologous to any well-known active sites such as the laminin active region, IKVAV. In parallel, searching the endogenous deletion mutants of NC in the rat brain, we cloned a mutant in which the region including the larger part of one of the three active regions was deleted. The neurite outgrowth activity of the mutant was significantly lower than that of normal NC. These results suggest the physiological significance of these active regions.     

Molecular cloning and characterization of FRAT2, encoding a positive regulator of the WNT signaling pathway

FRAT1 positively regulates the WNT signaling pathway by stabilizing beta-catenin through the association with glycogen synthase kinase-3beta. Here, we have cloned FRAT2 cDNAs, spanning the complete coding sequence, from a human fetal lung cDNA library. FRAT2 encoded 233 amino-acid protein, which showed 77.3% total amino-acid identity with FRAT1. FRAT2 and FRAT1 were more homologous in the acidic domain (96% identity), the proline-rich domain (92% identity), and the GSK-3beta binding domain (100% identity). The FRAT2 gene was mapped to human chromosome 10q24.1. The FRAT2 mRNA of 2.4-kb in size was relatively highly expressed in MKN45 (gastric cancer), HeLa S3 (cervical cancer), and K-562 (chronic myelogenous leukemia). Xenopus axis duplication assay revealed that the wild-type FRAT2 mRNA, but not the mutant FRAT2 mRNA lacking the acidic domain and the proline-rich domain, has the capacity to induce the secondary axis. These results indicate that FRAT2, just like FRAT1, functions as a positive regulator of the WNT signaling pathway. Thus, up-regulation of FRAT2 in human cancer might be implicated in carcinogenesis through activation of the WNT signaling pathway.     

Apoptosis induction by epigallocatechin gallate involves its binding to Fas

Epigallocatechin gallate (EGCG) is known to induce apoptosis in various types of tumor cells, but the precise mechanism by which EGCG induces apoptosis remains to be elucidated. The Fas-Fas ligand system is one of the major pathways operating in the apoptotic cascade. The aim of this study was to examine the possibility that EGCG-binding to Fas triggers the Fas-mediated apoptosis. The EGCG treatment of human monocytic leukemia U937 cells resulted in elevation of caspase 8 activity and fragmentation of caspase 8. The DNA ladder formation caused by the EGCG treatment was inhibited by the caspase 8 inhibitor. These findings suggested the involvement of the Fas-mediated cascade in the EGCG-induced apoptosis in U937 cells. Affinity chromatography revealed the binding between EGCG and Fas. Thus, the results suggest that EGCG-binding to Fas, presumably on the cell surface, triggers the Fas-mediated apoptosis in U937 cells.