Differential expression of decorin and biglycan genes during mouse tooth development.

Small leucine-rich proteoglycans (SLRPs) have a number of biological functions and some of them are thought to regulate collagen mineralizaton in bone and tooth. We have previously identified and immunolocalized two members of the SLRPs family, decorin and biglycan, in bovine tooth/periodontium. To investigate their potential roles in tooth development, we examined the mRNA expression patterns of decorin, biglycan and type I collagen in newborn (day 19) mice tooth germs by in situ hybridization. At this developmental stage, the first maxillary and mandibular molars include stages before and after secretion of the predentin matrix, respectively. The expression of decorin mRNA coincided with that of type I collagen mRNA and was mostly observed in secretory odontoblasts, while the biglycan mRNA was expressed throughout the tooth germ, including pre-secretory odontoblasts/ameloblasts, dental papilla and stellate reticulum. However, its signal in secretory odontoblasts was not as evident as that of decorin. In mandibular incisors, where a significant amount of predentin matrix and a small amount of enamel matrix were already secreted, a similar differential expression pattern was observed. In secretory ameloblasts the biglycan mRNA expression was apparent, while that of decorin was not. These differential expression patterns suggest the distinct roles of biglycan and decorin in the process of tooth development.     

Acute exercise increases expression of extracellular superoxide dismutase in skeletal muscle and the aorta

Exercise dramatically increases oxygen consumption and causes oxidative stress. Superoxide dismutase (SOD) is important in the first-line defence mechanisms against oxidative stress. To investigate the effect of acute exercise on the expression of SOD, we examined the expression of mRNA for three SOD isozymes, in mice run on a treadmill to exhaustion. Six hours after exercise, the expression of extracellular SOD (EC-SOD) mRNA increased significantly in skeletal muscle and persisted for 24 h, whereas no change was observed for cytoplasmic and mitochondrial SOD mRNA. Moreover, acute exercise also induced EC-SOD mRNA in the aorta. These results suggest that a single bout of exercise is enough to augment the expression EC-SOD mRNA in skeletal muscle and the aorta, and may partly explain the beneficial effect of exercise.     

Synthesis of 6-Sulfur Analogues of Oxanosine and Closely Related Derivatives Thereof

Abstract

Novel β-D-ribofuranosides having a 5-substituted imidazo [4,5-d] [1,3]thiazine ring, including the S⁶-congener 3 of oxanosine 2, were synthesized for screening their anticancer and antiviral activities.     

ATP-induced shrinkage of DNA with MukB protein and the MukBEF complex of Escherichia coli

Fluorescence microscopic observation of individual T4 DNA molecules revealed that the MukBEF complex (bacterial condensin) and its subunit, the MukB (a member of the SMC [structural maintenance of chromosomes] superfamily) homodimer, of Escherichia coli markedly shrunk large DNA molecules in the presence of hydrolyzable ATP. In contrast, in the presence of ADP or ATP-gammaS, the conformation of DNA was almost not changed. This suggests that the ATPase activity of subunit MukB is essential for shrinking large DNA molecules. Stretching experiments on the shrunken DNA molecules in the presence of ATP and MukBEF indicated a cross-bridging interaction between DNA molecules.     

Structural analysis of O-glycans of mucin from jellyfish (Aurelia aurita) containing 2-aminoethylphosphonate

The structure of O-glycan in qniumucin (Q-mucin), which is a novel mucin extracted from jellyfish, was analyzed by a combination of NMR and ESI-MS/MS. A previously unidentified monosaccharide involved in the glycan chains was determined to be N-acetylgalactosamine (GalNAc) substituted by 2-aminoethylphosphonate (AEP) at the C-6. The O-glycans in Q-mucin from Aurelia aurita were proved to be mainly composed of three monosaccharides: GalNAc, AEP-(O→6)-GalNAc, and P-6-GalNAc. To the best of our knowledge, this is the first example of an O-glycan structure of glycoproteins containing AEP. This exceptionally simple structure of Q-mucin and its potential use in material science and technology are revealed.     

Further characterization of the PW peptide family that inhibits neuron differentiation in <Emphasis Type="Italic">Hydra</Emphasis>

From an evolutionary point of view, Hydra has one of the most primitive nervous systems among metazoans. Two different groups of peptides that affect neuron differentiation were identified in a systematic screening of peptide signaling molecules in Hydra. Within the first group of peptides, a neuropeptide, Hym-355, was previously shown to positively regulate neuron differentiation. The second group of peptides encompasses the PW family of peptides that negatively regulate neuron differentiation. In this study, we identified the gene encoding PW peptide preprohormone. Moreover, we made the antibody that specifically recognizes LPW. In situ hybridization and immunohistochemical analyses showed that the PW peptides and the gene encoding them were expressed in ectodermal epithelial cells throughout the body except for the basal disk. The PW peptides are produced by epithelial cells and are therefore termed “epitheliopeptides.” Together with Hym-355, the PW family peptides mediate communication between neurons and epithelial cells and thereby maintain a specific density of neurons in Hydra. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Toshio Takahashi, Osamu Koizumi equally contributed to this study.     

Molecular mechanism of cell proliferation in rodent uterus during the estrous cycle

The rodent uterus is a widely studied target tissue for sexual steroid hormone action. The aim of the present study was to assess the molecular mechanism that participates in the initiation of cell proliferation of the rat uterine epithelial cells during the estrus (E)–metestrus (M) transition. Cell proliferation, ERα, c-fos, cyclin D1 and D3, cdk4, and cdk6 proteins were assessed in these animals by immunohistochemistry. Estradiol (E₂) and progesterone (P₄) plasma levels were assessed by RIA. The results indicate that the glandular epithelium starts to proliferate at 21:00 h on estrus day, and initiates at least 3 h before the luminal epithelium does. Fos expression was markedly increased during the afternoon of estrus day, and its increase was in parallel to ERα expression. Interestingly, both, cyclin D1 and D3 were abundantly expressed in the luminal and glandular epithelia, and nuclear immunolabelling of cyclin D1 and D3 precedes BrdU incorporation in the cell. cdk4 and cdk6 were localized in the nuclei in both epithelia throughout the studied time course. In addition, cdk4 was more abundant throughout estrus and metestrus days than cdk6. The overall results indicate that ERα, Fos and cyclins D1 and D3, cdk4 and cdk6 are expressed in both glandular and luminal epithelia of the rat uterus during the E–M transition. In conclusion, there is a good correlation between sequential expression of these proteins and cell cycle progression in the rat uterine epithelial cells during the estrous cycle. However, the differences observed in the cellular localization, time course of expression and the cellular types that express both cyclins between physiological and pharmacological conditions, demonstrated different mechanisms of regulation and should be due to the complex hormonal milieu during the estrous cycle.     

Connexin 32 down-regulates the fibrinolytic factors in metastatic renal cell carcinoma cells

Fibrinolytic factors have an important role in tumor progression through the degradation of extracellular matrix. The increased levels of urokinase-type plasminogen activator (uPA), uPA-receptor (uPAR) and type-1 PA inhibitor (PAI-1) are reported in human renal cell carcinoma (RCC). Connexin (Cx) gene, a member of gap junction, is known to act as a tumor suppressor gene. We have reported that Cx32 improves malignant phenotypes of metastatic RCC cells via the inhibition of Src-dependent signaling. In this study, we examined the effect of expression of Cx32 gene on the production of uPA, uPAR and PAI-1, and on the induction of PAI-1 stimulated by hypoxia in a human metastatic RCC cell line, Caki-1 cells. Cx32 expression decreased both mRNA level and production of PAI-1, uPA and uPAR in Caki-1 cells. Cx32 also decreased hypoxia-inducible factor (HIF)-1alpha and HIF-2alpha mRNA level. PP1, a Src inhibitor, significantly decreased PAI-1, uPA, uPAR and HIF-alpha mRNA levels in Caki-1 cells. Furthermore, Cx32 suppressed the induction of HIF-2alpha protein in Caki-1 cells under hypoxia. PAI-1 mRNA level in Cx32-transfected Caki-1 cells was lower than that of mock transfectant under hypoxic conditions. These results suggest that Cx32 might reduce PAI-1, uPA and uPAR production in metastatic RCC cells via the inhibition of Src-dependent induction of HIF-1alpha and HIF-2alpha gene expression and that Cx32 might suppress hypoxia-inducible gene expression under hypoxic conditions.