Characterization of osteoblastic differentiation of stromal cell line ST2 that is induced by ascorbic acid

The stromal cell line ST2, derived from mouse bone marrow, differentiated into osteoblast-like cells in response to ascorbic acid. Ascorbic acid induced alkaline phosphatase (ALPase) activity, the expression of mRNAs for proteins that are markers of osteoblastic differentiation, the deposition of calcium, and the formation of mineralized nodules by ST2 cells. We investigated the mechanism whereby ascorbic acid induced the differentiation of ST2 cells. Inhibitors of the formation of collagen triple helices completely blocked the effects of ascorbic acid on ST2 cells, an indication that matrix formation by type I collagen is essential for the induction of osteoblastic differentiation of ST2 cells by ascorbic acid. We furthermore examined the effects of bone morphogenetic proteins (BMPs) on the differentiation of ST2 cells induced by ascorbic acid. Ascorbic acid had no effect on the expression of mRNAs for BMP-4 and the BMP receptors. However, a soluble form of BMP receptor IA inhibited the induction of ALPase activity by ascorbic acid. These results suggest that ascorbic acid might promote the differentiation of ST2 cells into osteoblast-like cells by inducing the formation of a matrix of type I collagen, with subsequent activation of the signaling pathways that involve BMPs.

A possible mechanism of primary ciliary dyskinesia: a case of a segmental defect in ciliary microtubules

We report here a 13-year-old woman with cough, sputum and fever. The patient had both chronic sinusitis and bronchitis. Chest X-ray and computed tomographic scan of the chest revealed mucous bronchial filling and bronchiectasia in bronchi of bilateral lower lobes, right middle lobe and left upper lobe. Aerosol inhalation scintigraphy with 99mTechnetium demonstrated delays of the discharged tracer. On the basis of these findings, primary ciliary dyskinesia was suggested. This was confirmed by the findings from nasal biopsy with transmission electron microscopy where all of the microtubules were segmentally defected near the basal body in the cilia. On the basis of these findings, we diagnosed the patient with primary ciliary dyskinesia which may be due, at least in part, to segmental defect of ciliary microtubules.

Ipriflavone down-regulates endothelin receptor levels during differentiation of rat calvarial osteoblast-like cells

Ipriflavone (7-isopropoxy-3-phenyl-4H-1-benzopyran-4-one) is a synthetic flavonoid that has been shown to stimulate the activity of osteoblasts. We show here that ipriflavone also promotes the deposition of calcium and the formation of mineralized nodules by newborn rat calvarial osteoblast-like (ROB) cells as well as the activity of alkaline phosphatase. We reported previously that endothelin-1 inhibits the differentiation of ROB cells [Y. Hiruma et al. (1998) J. Cardiovasc. Pharmacol. 31, S521-S523]. Therefore, we examined the effects of ipriflavone on the expression of endothelin receptors in ROB cells by polymerase chain reaction-Southern blot analysis and in binding assays with 125I-labeled endothelin-1. Ipriflavone reduced levels of endothelin ETA receptors (to 48% of the control level) in ROB cells around day 7 in our standard cultures, while it had no apparent effect on the expression of the mRNA for the endothelin ETA receptor. By contrast, treatment with 10(-7) M endothelin-1 on days 6 through 9 alone suppressed mineralization by ROB cells. Ipriflavone also reduced the ability of endothelin-1 to inhibit mineralization by ROB cells. These results suggest that the acceleration of osteoblastic differentiation by ipriflavone might be due, at least in part, to a time-specific down-regulation of endothelin receptors.

Correlation between induction of expression of biglycan and mineralization by C-type natriuretic peptide in osteoblastic cells

We reported previously that C-type natriuretic peptide (CNP) promotes the differentiation and mineralization of osteoblastic cells [Am. J. Physiol. 270 (Cell Physiol. 39): C1311-C1318, 1996]. However, little information is available about the mechanism of action of CNP in differentiating osteoblastic cells. Using the technique known as differential display-polymerase chain reaction, we attempted to identify the mRNAs whose levels are regulated by CNP in mouse clonal preosteoblastic MC3T3-E1 cells. One species of mRNA whose level was increased by CNP was 99% homologous to the 3'-untranslated region of a mouse gene for biglycan (BGN), a small proteoglycan. BGN is known to be involved in bone formation by osteoblastic cells. Therefore, we investigated the relationship, during the formation of mineralized nodules, between CNP and BGN using calvarial osteoblast-like cells (ROB cells) from newborn rats, that are a good model for studies on bone formation in vitro. Northern blot analysis revealed that transcription of the mRNA for BGN was up-regulated by CNP in ROB cells on days 6 and 8, whereas no effect of CNP was observed on days 3 and 12. Brief treatment with 10(-7) M CNP on days 3 through 9 exclusively enhanced the deposition of calcium, a result that suggests that CNP might regulate the expression of mineralization-related genes and, probably, the gene for BGN during a specific time period.

Guaianolides as immunomodulators. Synthesis and biological activities of dehydrocostus lactone, mokko lactone, eremanthin, and their derivatives

The naturally occurring guaianolides, namely mokko lactone (1), dehydrocostus lactone (2), eremanthin (3), and related guaianolides, 16, 17, 21, 22, 28-31, 33, 36, 37, and 39, have been synthesized starting from l-alpha-santonin in an effort to examine their structure-activity relationship as inhibitors of the killing function of cytotoxic T lymphocytes (CTL) and the induction of intercellular adhesion molecule-1 (ICAM-1). It was observed during the present study that the guaianolides possessing an alpha-methylene gamma-lactone moiety, i.e., 2, 3, 30, 33, 37, and 39, exhibited significant inhibitory activity toward the killing function of CTL and the induction of ICAM-1.

Laminar shear stress-induced GRO mRNA and protein expression in endothelial cells

BACKGROUND

The shear stress induced by blood flow may play a pivotal role in the induction or prevention of atherosclerosis by changing endothelial functions. To disclose the mechanisms of this change, we prepared an endothelial cell (EC) cDNA library to select specific clones expressed in response to shear stress.

METHODS AND RESULTS

The mRNA of cultured confluent bovine aortic ECs (BAECs) subjected to steady laminar shear stress (30 dyne/cm2) for 4 hours was separated, and a cDNA library was prepared. Nine clones whose expressions were specifically enhanced by the shear stress were selected by use of a differential hybridization method. One clone had 94% homology at the nucleotide sequence level to Oryctolagus cuniculus gro (GRO) mRNA and 79% homology at the amino acid sequence level to human GRO-beta. The GRO mRNA expression was increased in both BAECs and human umbilical vein ECs (HUVECs) after the ECs were subjected to high (30 dyne/cm2) and low (5 dyne/cm2) laminar shear stress. GRO-alpha and/or -beta protein expression also increased after the HUVECs and BAECs were subjected to shear stress. Because GRO protein has been shown to function as an adhesion factor of monocytes on the surface of ECs, we studied whether shear stress-induced monocyte adhesion was caused by GRO protein expression on ECs. The 4-hour shear stress enhanced monocyte adhesion to ECs by 2.5-fold over control levels, and this enhancement was inhibited by 53% by anti-GRO-alpha antibody.

CONCLUSIONS

The present study is the first report that shear stress induced the expression of GRO mRNA and protein in ECs and enhanced the monocyte adhesion on ECs via GRO protein. Further investigations of the functions and participation in atherogenesis of this selected clone may clarify the significance of shear stress on atherogenesis.

A new mutation in the POU3F4 gene in a Japanese family with X-linked mixed deafness (DFN3)

OBJECTIVE

The molecular defect in patients with X-linked mixed deafness showing a perilymphatic gusher at stapedectomy (DFN3) has been attributed to mutations in the POU3F4 gene. This study aimed to clarify an allelic variant of this gene.

STUDY DESIGN

This was a genetic study of a single Japanese family with DFN3.

METHODS

Products of a polymerase chain reaction (PCR) were subjected to single-strand conformation polymorphism (SSCP) analysis. Direct sequencing of PCR products from patients and carriers showing SSCP variants was performed using the fluorescent dideoxy termination method and a sequencer.

RESULTS

Sequencing of the PCR product revealed a 6-base deletion (TTCAAA) at nucleotides 601 to 606, resulting in a two-amino-acid deletion in the POU3F4 protein, (phenylalanine and lysine at amino acid residues 201 and 202). The deletion was adjacent to the site of a nonsense mutation previously described.

CONCLUSION

Microdeletions at a previously undescribed location account for some clinically important POU3F4 mutations.

Endothelins inhibit the mineralization of osteoblastic MC3T3-E1 cells through the A-type endothelin receptor

We examined the effects of various endothelins on the mineralization of mouse clonal preosteoblastic MC3T3-E1 cells. MC3T3-E1 cells expressed mRNAs for endothelin (ET)-1 and the A-type receptor for ET (ETA). A pharmacological study also demonstrated the predominant expression of the ETA receptor. Northern blotting analysis revealed that ETs decreased the expression of mRNA for osteocalcin, which is a marker protein for the maturation of osteoblastic cells. ET-1 also decreased in the deposition of calcium by MC3T3-E1 cells in a dose-dependent manner and it had an inhibitory effect even at 10(-11) M. The rank order of potency of ETs was ET-1 = ET-2 > ET-3. Brief treatment with 10(-7) M ET-1 on days 6-8 alone suppressed mineralization. ET-1 enhanced the rate of production of inositol 1,4, 5-trisphosphate (IP3) in MC3T3-E1 cells, but it had no effect on the rate of production of cAMP. Taken together, our data indicate that ET-1 might inhibit the mineralization of osteoblastic cells via an interaction with the ETA receptor, with generation of IP3 as the intracellular signal.

Effects of nitric oxide from exogenous nitric oxide donors on osteoblastic metabolism

We examined the effects of nitric oxide (NO) on the differentiation and mineralization of newborn rat calvarial osteoblastic cells (ROB cells) using exogenous NO donors, sodium nitroprusside, 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamin e (NOC-7) and 2,2'-(hydroxynitrosoydrazino)bis-ethanamine (NOC-18). Sodium nitroprusside and NOC-7 dose-dependently enhanced the rate of production of intracellular cGMP in ROB cells and the rat clonal osteogenic cell line ROB-C26. We used NOC (NOC is the trade name for NO complex manufactured by Dojindo, Kumamoto, Japan) as an NO donor in our experiments because sodium nitroprusside exhibited a marked cytotoxicity. Northern blot analysis revealed that the level of mRNA for osteocalcin, one of the osteoblastic differentiation markers, was enhanced in the ROB cells, which was continuously treated by NOC-18. NOC-18, however, did not affect the level of mRNA for alkaline phosphatase and the activity of alkaline phosphatase. Both the number and the total area of mineralized nodules that are a model of in vitro bone formation were shown to be increased by 10(-5) M NOC-18. Our data suggest that NO might act as a local regulator of the metabolism of osteoblastic cells.

Endothelins inhibit mineralization of rat calvarial osteoblast-like cells

We examined the effects of members of the endothelin (ET) family on mineralization of rat calvarial osteoblast-like cells. The accumulation of calcium in cells and cell layers was attenuated by ETs with the rank order of potency ET-1 = ET-2 > ET-3. We stained the mineralized nodules by von Kossa staining and measured the number and area of mineralized nodules. The inhibitory effects of ET-1 and ET-2 on the formation of mineralized nodules were stronger than those of ET-3. Our data suggest that ET-1 may inhibit the mineralization process of osteoblastic cells through the ETA receptor.

Deceleration by angiotensin II of the differentiation and bone formation of rat calvarial osteoblastic cells

We examined the effects of angiotensin II (Ang II) on the differentiation of rat calvarial osteoblastic cells and on the formation of bone by these cells. Northern blotting analysis revealed that Ang II inhibited the expression of mRNA for osteocalcin, which is a protein that is specifically expressed during maturation of osteoblastic cells. Ang II decreased the activity of alkaline phosphatase, a marker of osteoblastic differentiation, in the cells, acting via the type 1 (AT1) receptor. We used von Kossa staining to examine the formation of mineralized nodules by osteoblastic cells. Both the number and the total area of mineralized nodules were quantified and shown to be decreased by 10(-7) M Ang II. The accumulation of calcium in cells and the matrix layer was also decreased by Ang II. Binding analysis with subtype-specific antagonists revealed the presence of AT1 receptors for Ang II in this culture system. Ang II caused a marked increase in the rate of production of intracellular cAMP in this system. Our data suggest that Ang II might be intimately involved in osteoblastic metabolism through its interaction with the AT1 receptor.

Enantioselective Total Syntheses of (-)-7betaH-Eudesmane-4alpha,11-diol and (+)-ent-7betaH-Eudesmane-4alpha,11-diol

The syntheses of (-)-7betaH-eudesmane-4alpha,11-diol (2) and (+)-ent-7betaH-eudesmane-4alpha,11-diol (ent-2) were carried out starting from (-)- and (+)-dihydrocarvones. As a result, the structure, including absolute configuration, of the naturally occurring eudesmane-4,11-diol isolated from Pluchea arguta was determined to be (+)-ent-7betaH-eudesmane-4alpha,11-diol (ent-2).

Caveolae: from a morphological point of view

Caveolae in the plasma membrane have been a focus of intensive research during the past several years. There has been confusion concerning caveolae and caveola-like membrane domains, but it is now generally thought that the latter is a region distinct from caveolae. However, due to similar buoyancy of caveolae and caveola-like membranes, whether caveolae in situ are enriched with a given molecule is often difficult to be concluded by biochemical techniques alone. Furthermore, relatively shallow caveolae may be detected by some techniques, but not by others. Thus whether a molecule is enriched in caveolae should be confirmed by methods based on different principles. Among many putative caveolar molecules, those related to Ca2+ influx and extrusion were shown to be concentrated in caveolae by both immunocytochemical and biochemical techniques. In conjunction with other characteristics, the result implies that caveolae may function as a mobile compartment for Ca2+ signalling.

Circadian rhythm estimation by core body temperature filtered with simultaneously recorded physiological data

In field measurements, monitoring of core body temperature is influenced by physical activities; therefore, the estimation of circadian rhythm from the data may not be exact. The purpose of this study is to design a core body temperature filter in order to reduce artifacts induced by physical activities using simultaneously recorded physiological data such as heart rate data. The effects of physical activities on core body temperature and heart rate are assessed through three experiments. Based on the above knowledge, a core body temperature filter was designed. The filter removes part of rectal temperature data as artifact when heart rate rises above a predetermined threshold. As a result, most of the spike-like noise was removed and the filtered temperature data showed sinusoidal variation more than the unfiltered data. The mesor of the estimated rhythm significantly decreased. This filtering method can provide more precise information about circadian rhythm, especially in field measurements.

Expression profiles of transcripts from 126 open reading frames in the entire chromosome VI of Saccharomyces cerevisiae by systematic northern analyses

Chromosome VI of Saccharomyces cerevisiae contains 126 open reading frames (ORFs), and the functions of proteins encoded by 80 ORFs are still unknown. In this report, we have systematically examined the expression profiles of all 126 ORFs on chromosome VI under five kinds of growth conditions by quantitative Northern hybridization. A series of Northern analyses and reverse transcription polymerase chain reactions have revealed that more than 64 novel ORFs are transcribed. Two ORFs (YFL059w and YFR011c) are specifically expressed in the presence of galactose. Two ORFs (YFL012w and YFR032c) are specifically transcribed in sporulation. Six ORFs (YFL049w, YFL035c, YFL010c, YFR006w, YFR010w and YFR017c) are abundantly expressed in many growth conditions.

Development of striated rootlets during ciliogenesis in the human oviduct epithelium

Striated rootlets in ciliated cells are conical banded structures composed of longitudinally aligned filaments. The formation of striated rootlets during ciliognesis in the human oviduct epithelium was studied by electron microscopy. Primitive rootlets appeared at the proximal side of basal bodies before or at the same time as ciliary budding. After the formation of several striations, the tip of the rootlets extended deeply toward the interior of the cell and became differentiated into two distinct parts, viz., the proximal conical part connected to the basal body and the distal fibrillar part. The periodicity of the striations in the fibrillar part was 68. 5+/-2.95 nm, about 5 nm longer than that of the conical part (63. 9+/-2.25 nm). The dark band in the striation was thicker in the fibrillar part than in the conical part. Since the fibrillar part was not observed in the mature cilium, this part was considered as being either degraded or changed into the conical part during ciliogenesis.

Partial cloning of the hormone-binding domain of the cortisol receptor in tilapia, Oreochromis mossambicus, and changes in the mRNA level during embryonic development

Cortisol is one of the central hormones in osmoregulation in fish, especially in seawater adaptation. A cDNA of 453 bp was cloned from liver mRNA of freshwater-reared tilapia (Oreochromis mossambicus), by reverse transcription polymerase chain reaction (RT-PCR) with primers designed for the hormone-binding domain of glucocorticoid receptors (GRs) in mammals and rainbow trout. The sequence of PCR product has 83% homology to the trout GR at the nucleotide level and 92% at the amino acid level. The PCR product of tilapia showed highest homology (74% at the amino acid level) to GR among human steroid hormone receptors, including mineralocorticoid receptor. The length of the receptor mRNA of tilapia was about 6.5 kb as determined by Northern blot hybridization. The mRNA concentration in the gills was relatively higher among various organs, the highest concentration being observed in blood cells. Signal intensity of the receptor message in the gills was stronger in fish reared in freshwater than in those reared in seawater or in concentrated (160%) seawater. During early development of tilapia, the highest concentration of receptor mRNA in the total RNA extracted from the whole egg was found just after fertilization, and its concentration decreased steadily toward hatching. The absolute amount of receptor mRNA per egg increased gradually before the initiation of cortisol production by the embryo. When embryos were transferred from fresh water to seawater 2 days before hatching, no difference was observed in the signal intensity of the receptor mRNA among embryos after 1, 2 (the day of hatching), 4, and 7 days.

Ultrastructural observation on 'transitional tubules' in human oviductal ciliogenic cells

In the human oviduct epithelium during ciliogenesis, short tubular structures were found in the transitional zone between the basal body and cilium. The tubules, termed transitional tubules from their location, were 34-36 nm in diameter and 0.13 +/- 0.06 micron in length; the number around a basal body was variable, but usually 4-6. The cytoplasmic leaflets of the tubule membranes were coated by electron-dense material and appeared to be connected to alar sheets. The transitional tubules existed transiently during ciliogenesis. The exact role of transitional tubules is unknown, but considering their location, they may fix the basal body in the apical cytoplasm during ciliary elongation and/or may be related to formation of alar sheets.

Peculiar distribution of fodrin in fat-storing cells

Fat-storing cells (FSCs) show unique morphology containing many lipid droplets in the cytoplasm. In this study, we found that a membrane skeletal protein, fodrin, shows peculiar distribution in FSCs of rat liver. By immunofluorescence microscopy of FSCs in culture, intense labeling for fodrin was seen as coarse filaments in the cytoplasm. Especially in FSCs isolated from vitamin A-treated rats, the labeling was often seen as many small rings in the cytoplasm. In contrast, labeling for fodrin in human fibroblasts or rat adipocytes in culture was seen diffusely in the cell cortex. Distribution of actin, tubulin, vimentin, and desmin in FSCs was also examined, but none of them appeared correlated with fodrin. By immunoelectron microscopy using nanogold labeling with silver enhancement, positive labeling for fodrin was seen around some lipid droplets in FSCs in vivo. We assume that the peculiar distribution of fodrin may be related to the morphological characteristics of FSCs.

Interrelation between nitric oxide synthase and heme oxygenase in rat endothelial cells

The gene expression and interrelation of the constitutive type nitric oxide (NO) synthase-III as a NO-forming enzyme and heme oxygenase-2 as a carbon monoxide-forming enzyme were studied in cultured rat aortic endothelial cells. Both NO synthase-III and heme oxygenase-2 mRNAs were demonstrated in the endothelial cells by RNAase protection analysis. NO synthase-III mRNA was upregulated in the presence of the heme oxygenase inhibitor, zinc protoporphyrin IX, but not in the presence of the NO synthase inhibitor, N(G)-nitro-L-arginine. Although heme oxygenase-2 mRNA was significantly upregulated in the presence of both NO synthase inhibitor and heme oxygenase inhibitor, the increase was greater with the NO synthase inhibitor. These results provide the first evidence for the concomitant gene expression of NO synthase-III and heme oxygenase-2, and their compensatory interrelation in endothelial cells.