Non-radioisotopic quantitative RT-PCR to detect changes in mRNA levels during early mouse embryo development

Impact of dioxins on reproductive health in female mammals

Extensive research has been conducted to investigate the toxicological impact of dioxins on mammals, revealing profound effects on the female reproductive system in both humans and animals. Dioxin exposure significantly disrupts the intricate functions of the ovary, a pivotal organ responsible for reproductive and endocrine processes. This disruption manifests as infertility, premature ovarian failure, and disturbances in sex steroid hormone levels. Comprehensive studies, encompassing accidental human exposure and experimental animal data, have raised a wealth of information with consistent yet varied conclusion influenced by experimental factors. This review begins by providing an overarching background on the ovary, emphasizing its fundamental role in reproductive health, particularly in ovarian steroidogenesis and hormone receptor regulation. Subsequently, a detailed examination of the Aryl hydrocarbon Receptor (AhR) and its role in governing ovarian function is presented. The review then outlines the sources and toxicity of dioxins, with a specific focus on AhR involvement in mediating reproductive toxicity in mammals. Within this context, the impact of dioxins, notably 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), on Folliculogenesis and Preimplantation embryos is discussed. Furthermore, the review delves into the disruptions of the female hormonal system caused by TCDD and their ramifications in endometriosis. Notably, variations in the effects of TCDD on the female reproductive and hormonal system are highlighted in relation to TCDD dose, animal species, and age. As a forward-looking perspective, questions arise regarding the potential involvement of molecular mechanisms beyond AhR in mediating the female reproductive toxicity of dioxins.

Transcriptional, hormonal and histological alterations in the ovaries of BALB/c mice exposed to TCDD in connection with multigenerational female infertility

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener of dioxins, has a proven reproductive toxicity. Due to the lack of evidence on the multigenerational female reproductive toxicity of TCDD through the maternal exposure, the current study aims to evaluate, on the one hand, the acute reproductive toxicity of TCDD on adult female pre-gestational exposed to a critical single dose of TCDD (25 μg/kg) for a week (group referred to as AFnG; adult female/non-gestation). On the other hand, the transcription, hormonal and histological effects of TCDD on the females of two generations F1 and F2, were also investigated after the exposure of pregnant females to TCDD on gestational day 13 (GD13) (group referred to as AFG; adult female/gestation). First, our data showed alternations in the ovarian expressional pattern of certain key genes involved in the detoxification of TCDD as well as in the biosynthesis of steroidal hormones. The expression of Cyp1a1 was highly induced in TCDD-AFnG group, but reduced in both F1 and F2. While the transcripts levels of Cyp11a1 and 3βhsd2 were decreased, Cyp19a1 transcripts were increased as a function of TCDD exposure. This was synchronized with a dramatic increase in the level of estradiol hormone in the females of both experimental groups. Beside a significant reduce in their size and weight, ovaries of TCDD-exposed females showed serious histological alterations marked by atrophy of the ovary, congestion in the blood vessels, necrosis in the layer of granular cells, dissolution of the oocyte and nucleus of ovarian follicles. Finally, the female fertility was dramatically affected across generations with a reduced male\female ratio. Our data indicate that the exposure of pregnant female to TCDD has serious negative effects in the female productive system across generations and suggest the use of hormonal alternation as biomarker to monitor and assess the indirect exposure of these generations to TCDD.

Post-Translational Modifications in Oocyte Maturation and Embryo Development

Mammalian oocyte maturation and embryo development are unique biological processes regulated by various modifications. Since de novo mRNA transcription is absent during oocyte meiosis, protein-level regulation, especially post-translational modification (PTM), is crucial. It is known that PTM plays key roles in diverse cellular events such as DNA damage response, chromosome condensation, and cytoskeletal organization during oocyte maturation and embryo development. However, most previous reviews on PTM in oocytes and embryos have only focused on studies of Xenopus laevis or Caenorhabditis elegans eggs. In this review, we will discuss the latest discoveries regarding PTM in mammalian oocytes maturation and embryo development, focusing on phosphorylation, ubiquitination, SUMOylation and Poly(ADP-ribosyl)ation (PARylation). Phosphorylation functions in chromosome condensation and spindle alignment by regulating histone H3, mitogen-activated protein kinases, and some other pathways during mammalian oocyte maturation. Ubiquitination is a three-step enzymatic cascade that facilitates the degradation of proteins, and numerous E3 ubiquitin ligases are involved in modifying substrates and thus regulating oocyte maturation, oocyte-sperm binding, and early embryo development. Through the reversible addition and removal of SUMO (small ubiquitin-related modifier) on lysine residues, SUMOylation affects the cell cycle and DNA damage response in oocytes. As an emerging PTM, PARlation has been shown to not only participate in DNA damage repair, but also mediate asymmetric division of oocyte meiosis. Each of these PTMs and external environments is versatile and contributes to distinct phases during oocyte maturation and embryo development.

The neglected part of early embryonic development: maternal protein degradation

The degradation of maternally provided molecules is a very important process during early embryogenesis. However, the vast majority of studies deals with mRNA degradation and protein degradation is only a very little explored process yet. The aim of this article was to summarize current knowledge about the protein degradation during embryogenesis of mammals. In addition to resuming of known data concerning mammalian embryogenesis, we tried to fill the gaps in knowledge by comparison with facts known about protein degradation in early embryos of non-mammalian species. Maternal protein degradation seems to be driven by very strict rules in terms of specificity and timing. The degradation of some maternal proteins is certainly necessary for the normal course of embryonic genome activation (EGA) and several concrete proteins that need to be degraded before major EGA have been already found. Nevertheless, the most important period seems to take place even before preimplantation development-during oocyte maturation. The defects arisen during this period seems to be later irreparable.

Inhibition of Skp1-Cullin-F-box complexes during bovine oocyte maturation and preimplantation development leads to delayed development of embryos†

The mechanism of maternal protein degradation during preimplantation development has not been clarified yet. It is thought that a lot of maternal proteins are degraded by the ubiquitin-proteasome system. In this study, we focused on the role of the SCF (Skp1-Cullin-F-box) complexes during early bovine embryogenesis. We inhibited them using MLN4924, an inhibitor of SCF complex ligases controlled by neddylation. Oocytes maturated in MLN4924 could be fertilized, but we found no cumulus cell expansion and a high number of polyspermy after in vitro fertilization. We also found a statistically significant deterioration of development after MLN4924 treatment. After treatment with MLN4924 from the four-cell to late eight-cell stage, we found a statistically significant delay in their development; some of the treated embryos were, however, able to reach the blastocyst stage later. We found reduced levels of mRNA of EGA markers PAPOLA and U2AF1A, which can be related to this developmental delay. The cultivation with MLN4924 caused a significant increase in protein levels in MLN4924-treated oocytes and embryos; no such change was found in cumulus cells. To detect the proteins affected by MLN4924 treatment, we performed a Western blot analysis of selected proteins (SMAD4, ribosomal protein S6, centromeric protein E, P27, NFKB inhibitor alpha, RNA-binding motif protein 19). No statistically significant increase in protein levels was detected in either treated embryos or oocytes. In summary, our study shows that SCF ligases are necessary for the correct maturation of oocytes, cumulus cell expansion, fertilization, and early preimplantation development of cattle.

Potential Involvement of SCF-Complex in Zygotic Genome Activation During Early Bovine Embryo Development

Proper timing of degradation of maternal protein reserves is important for early embryonic development. The major modification that triggers proteins to degradation is ubiquitination, mediated by ubiquitin-proteolytic system. We focus here on Skp 1-Cul 1-F-box complex (SCF-complex), E3 ubiquitin-ligase, a part of ubiquitin-proteolytic system, which transfer ubiquitin to the substrate protein. We describe in this chapter the methods for the characterization of the expression profile of mRNA and protein of invariant members of SCF-complex and for the definition of SCF-complex activity.

Effects of Positive Pressure in Odontogenic Keratocysts

Intracystic fluid pressure is thought to be involved in odontogenic cyst growth. In this study, we investigated the effects of positive pressure on the expression of interleukin-1α (IL-1α), matrix metalloproteinases (MMPs), and prostaglandin E2 (PGE2) in odontogenic keratocysts to determine whether this pressure stimulates inflammatory cytokine production and signaling of osteoclastogenic events. Positive pressure enhanced the expression of IL-1α mRNA and protein in odontogenic keratocyst epithelial cells, and increased the secretion of MMP-1, MMP-2, MMP-3, and PGE2 in a co-culture of odontogenic keratocyst fibroblasts and the epithelial cells. The pressure-induced secretions were inhibited by an interleukin-1 receptor antagonist. Recombinant human interleukin-1α (rhIL-1α) increased the secretion of MMP-1, MMP-2, MMP-3, and PGE2 in the fibroblasts. Furthermore, in the fibroblasts, rhIL-1α enhanced the expression of macrophage colony-stimulating factor (M-CSF) mRNA, and rhIL-1α-induced PGE2 increased the expression of nuclear factor κB ligand (RANKL) mRNA. Thus, positive pressure may play a crucial role in odontogenic keratocyst growth via stimulating the expression of IL-1α in epithelial cells.

Characterization of SCF-Complex during Bovine Preimplantation Development

The degradation of maternal proteins is one of the most important events during early development, and it is presumed to be essential for embryonic genome activation (EGA), but the precise mechanism is still not known. It is thought that a large proportion of the degradation of maternal proteins is mediated by the ubiquitin-proteolytic system. In this study we focused on the expression of the Skp1-Cullin1-F-box (SCF) complex, a modular RING-type E3 ubiquitin-ligase, during bovine preimplantation development. The complex consists of three invariable components—Cul1, Skp1, Rbx1 and F-box protein, which determines the substrate specificity. The protein level and mRNA expression of all three invariable members were determined. Cul1 and Skp1 mRNA synthesis was activated at early embryonic stages, at the 4c and early 8c stage, respectively, which suggests that these transcripts are necessary for preparing the embryo for EGA. CUL1 protein level increased from MII to the morula stage, with a significant difference between MII and L8c, and between MII and the morula. The CUL1 protein was localized primarily to nuclei and to a lesser extent to the cytoplasm, with a lower signal in the inner cell mass (ICM) compared to the trophectoderm (TE) at the blastocyst stage. The level of SKP1 protein significantly increased from MII oocytes to 4c embryos, but then significantly decreased again. The localization of the SKP1 protein was analysed throughout the cell and similarly to CUL1 at the blastocyst stage, the staining was less intensive in the ICM. There were no statistical differences in RBX1 protein level and localization. The active SCF-complex, which is determined by the interaction of Cul1 and Skp1, was found throughout the whole embryo during preimplantation development, but there was a difference at the blastocyst stage, which exhibits a much stronger signal in the TE than in the ICM. These results suggest that all these genes could play an important role during preimplantation development. This paper reveals comprehensive expression profile, the basic but important knowledge necessary for further studying.

Nimesulide inhibits the growth of human esophageal carcinoma cells by inactivating the JAK2/STAT3 pathway

Although selective COX-2 inhibitors have cancer-preventive effects and induce apoptosis, the mechanisms underlying these effects are not fully understood. This study investigated the effects of nimesulide, a selective COX-2 inhibitor, on apoptosis and on the JAK/STAT signaling pathway in Eca-109 human esophageal squamous carcinoma cells. The effects and mechanisms of nimesulide on Eca-109 cell growth were studied in culture and in nude mice with Eca-109 xenografts. Cells were cultured with or without nimesulide and/or the JAK2 inhibitor AG490. Cell proliferation was evaluated using the MTT assay, and apoptosis was investigated. COX-2 mRNA expression was measured using reverse transcription polymerase chain reaction, and protein expression was detected by Western blot analysis, immunohistochemistry, and flow cytometry. Nimesulide significantly inhibited Eca-109 cell viability in vitro in a dose- and time-dependent manner (P<0.05). Nimesulide also induced apoptosis, which was accompanied by a significant decrease in the expression of COX-2 and survivin and an increase in caspase-3 expression. Nimesulide downregulated the phosphorylation levels of JAK2 and STAT3, and JAK2 inhibition by AG490 significantly augmented both nimesulide-induced apoptosis and the downregulation of COX-2 and survivin (P<0.05). In vivo, nimesulide inhibited the growth of Eca-109 tumors and the expression of p-JAK2 and p-STAT3. Thus, nimesulide downregulates COX-2 and survivin expression and upregulates caspase-3 expression in Eca-109 cells, by inactivating the JAK2/STAT3 pathway. These effects may mediate nimesulide-induced apoptosis and growth inhibition in Eca-109 cells in vitro and in vivo.

Enhancing epithelial engraftment of rat mesenchymal stem cells restores epithelial barrier integrity

The cellular origin, in vivo function and fate of donor bone marrow-derived cells residing in the recipient intestinal epithelial cells, pericryptal myofibroblasts or endothelial cells remain obscure. Although 'immunoprivileged' mesenchymal stem cells (MSCs) are prime candidates for cell- and gene-based therapy, their precise role in colitis remains largely undetermined. Using a dextran sulphate sodium (DSS) colitis with busulphan (BU)-induced hypoplastic marrow model, we examined the therapeutic effects of MSC transplantation, focusing on the role of MSCs as both cell providers and immunomodulators. Donor-derived MSCs were detected by eGFP immunofluorescence and fluorescence in situ hybridization for Y-chromosome (Y-FISH) analysis. Western blot analysis of apical-most tight junction proteins was performed with antibodies against claudin-2, -7, -8, -12, -13, -15 and ZO-1. Cytokine and cell cycle profiles were analysed by semi-quantitative RT-PCR and flow cytometry. Susceptibility to DSS colitis was significantly increased by co-existing BU-induced bone marrow hypoplasia and this increase was significantly reduced by enhancing epithelial engraftment of MSCs, an effect depending on restoring epithelial barrier integrity rather than inhibiting host immune responses. We provide evidence that implicates MSCs in maintaining epithelial barrier function by reassembling apical-most tight junction proteins, claudins. The therapeutic efficacy of extrinsic MSCs depends on enhancing epithelial engraftment in damaged crypts by busulphan conditioning. Such a role for the MSC-derived intestinal cells in colitis therapy merits further examination and may offer a promising new treatment for inflammatory bowel disease (IBD).

Cathepsin Y Expression is Up-Regulated in Liver and Spleen of the Rats Growing under a Low Protein Diet

Background/Aims

We have previously isolated a novel lysosomal cysteine protease, cathepsin Y, which produces a kinin-potenciating octapeptide from rat plasma. The present study aimed to elucidate the influence of protein-restriction on cathepsin Y mRNA expression in tissues of growing rat.

Methods

Weaning rats were fed either 20% casein (normal-protein, NP) or 5% casein (low-protein, LP) diet for 12 weeks, from post-weaning period to maturity. Cathepsin Y mRNA expression in tissues was examined using RT-PCR and compared with that of cathepsin L, a general marker of muscle atrophy.

Results

Body, liver and spleen weights and diet intake of LP were significantly lower than those of NP. Cathepsin Y expression in LP was increased in liver (3.70 fold vs. NP) and spleen (1.28 fold) at early periods of protein-restriction, whereas that of cathepsin L was increased in liver and pectoral muscle through all intake periods. However, significant differences were detected in neither cathepsin Y expression in pectoral muscle nor cathepsin L expression in spleen throughout intake periods.

Conclusions

A significant up-regulation of cathepsin Y was observed in spleen and liver, suggesting that it may associate with immunodepression in rats under protein-malnutrition during the early post-weaning period.

Identification of novel genes expressed in hypoxic brain condition by fluorescence differential display

Fluorescence differential display (FDD) and comparative RT-PCR have been used extensively to detect differentially expressed genes. We investigated hypoxia-induced gene expression in the brain by FDD-PCR and comparative RT-PCR. Mice were anaesthetized after which hypoxia was induced by neck ligation for 1 min or 25 min, then were killed by decapitation, and the brains were dissected either immediately or 30 min after death (Group A1-0, Group A25-0, Group A1-30 and Group A25-30). Control mice without ligation of the neck were killed by decapitation under anaesthesia immediately (Group C-0) or 30 min after death (Group C-30). FDD-PCR, sequence analysis and comparative RT-PCR revealed that mitochondrial thymidine kinase 2, Rab6, selenoprotein T and two novel cDNAs were enhanced in Group A25-0 and Group A25-30 compared with the other groups. In Group A25-30, only RAP2 interacting protein and another novel cDNA were induced. In Group A25-0, one novel gene was detected. These findings were consistent with the results of statistical analysis by ANOVA. No differences of band pattern were observed among Groups A1-0, A1-30, C-0 and C-30. The genes exhibiting altered expression were associated with vital cellular functions, e.g., intracellular signaling and mitochondrial metabolism. In addition, we identified four novel genes, expressed after extended hypoxic conditions in mouse brain with suffocation. These results may contribute to clarify the pathophysiology of asphyxia in the brain and aid in the diagnosis of suffocation.

Expression profiling of glycosyltransferases using RT-PCR

The quantitative reverse-transcription polymerase chain reaction (RT-PCR) is a method used to quantify messenger RNA (mRNA) levels. It is particularly applicable to quantification of mRNAs that are transcribed at very low levels, such as glycosyltransferases (GTs). In this chapter, I describe preliminary experiments for obtaining conditions for a quantitative RT-PCR method to quantify transcript levels of GTs and related genes potentially involved in L-selectin-mediated lymphocyte homing in the mouse gastric mucosa infected by Helicobacter felis. This method was developed by modifying conventional RT-PCR protocols and does not require fluorescence-detecting thermal cyclers. The method described here is particularly useful for assaying large numbers of samples that require very accurate analysis.

Function analysis of steA homolog in Aspergillus oryzae

The asexual ascomycete Aspergillus oryzae has an steA homolog in its genome. The steA homolog of A. oryzae was transcribed in the wild-type strain but steA disruption did not affect the phenotype of the disruptant strain. On the other hand, the steA-overexpressing strain showed the restriction of vegetative hyphal growth and conidiation, and the formation of balloon-shaped structures. The restriction of vegetative hyphal growth and conidiation were partially rescued by high osmolarity. In addition, the hyphal growth of the steA-overexpressing strain was inhibited by Calcofluor white, and the strain was found to be sensitive to cell-wall-degrading reagents. Increase of secretory cell-wall-degrading enzymes of the steA-overexpressing strain was detected. These results indicate that SteA regulates cell-wall-degrading enzymes and that the phenotypes of A. oryzae steA-overexpressing strain may be due to cell wall abnormalities. steA may participate in cell wall metabolism.

Ca2+ stimulates COX-2 expression through calcium-sensing receptor in fibroblasts

Fibroblasts isolated from jaw cysts expressed calcium-sensing receptor (CasR). In the fibroblasts elevated extracellular Ca(2+) ([Ca(2+)](o)) increased fluo-3 fluorescence intensity, and the production of inositol(1,4,5)trisphosphate and active protein kinase C. Phospholipase C inhibitor U-73122 attenuated the Ca(2+)-induced increase in fluo-3 fluorescence intensity. Elevated [Ca(2+)](o) enhanced the expression of cyclooxygenase-2 (COX-2) mRNA and protein, and the secretion of prostaglandin E(2) in the fibroblasts. CasR activator neomycin also increased the expression of COX-2 mRNA, and U-73122 attenuated the Ca(2+)-induced expression of COX-2 mRNA. Elevated [Ca(2+)](o)-induced phosphorylation of extracellular signal-regulated protein kinase-1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK), and U-73122 inhibited the Ca(2+)-induced phosphorylation. The inhibitors for each kinase, PD98059, SB203580, and SP600125, attenuated the Ca(2+)-induced expression of COX-2 mRNA. These results suggest that in jaw cyst fibroblasts elevated extracellular Ca(2+) may enhance COX-2 expression via the activation of ERK1/2, p38 MAPK, and JNK through CasR.

Antisense therapy of MAdCAM-1 for trinitrobenzenesulfonic acid-induced murine colitis

BACKGROUND

Anti-alpha4 integrin reagent, natalizumab, which is 1 of the most promising antiadhesion monoclonal antibodies, has been introduced into clinical trials against inflammatory bowel disease (IBD). Lethal consequences such as progressive multifocal leukoencephalopathy have recently been reported in patients using natalizumab, making it critical to determine which selective adhesion molecule in the alpha4 integrins-dependent pathway should be targeted for inhibition and the minimal spectrum of activity required for the valid treatment of IBD. Mucosal addressin cell adhesion molecule (MAdCAM)-1 is known to be restrictedly expressed in gut-associated lymphoid tissues, and its expression dramatically increases in IBD. This study aimed to reevaluate the effectiveness of MAdCAM-1 inhibition and to determine the feasibility of anti-MAdCAM-1 strategy.

MATERIALS AND METHODS

Antisense MAdCAM-1 oligonucleotides were injected into mice at 1.5 mg/kg/day for 7 consecutive days from the first day of a trinitrobenzene sulfonate enema.

RESULTS

MAdCAM-1 antisense oligonucleotides significantly suppressed the development of trinitrobenzene sulfonate colitis clinically and histopathologically compared with controls. Immunohistochemistry and semiquantitative reverse-transcription polymerase chain reaction of the colon tissues revealed that MAdCAM-1 protein and mRNA expression were lower in antisense-treated mice than in controls. In addition, MAdCAM-1 antisense treatment reduced the number of alpha4beta7 lymphocytes in the inflamed colonic mucosa.

CONCLUSIONS

These data suggest that antisense suppression of MAdCAM-1 is of equivalent effectiveness to that of anti-MAdCAM-1 or anti-alpha4 integrin antibody in previous reports and could be a new therapy for IBD.

Accumulation of an intron-retained mRNA for granulocyte macrophage-colony stimulating factor receptor common beta chain in neutrophils of myelodysplastic syndromes

We recently identified a reduction in the neutrophil surface expression of common beta chain (beta c) of the receptor for granulocyte macrophage-colony stimulating factor (GM-CSF) in the patients with myelodysplastic syndromes (MDS). To determine the etiology of the impaired beta c expression, beta c mRNA from neutrophilic granulocytes of MDS patients and healthy controls was analyzed by a combination of direct reverse transcriptase-polymerase chain reaction-based single-strand conformational polymorphism and sequencing. Nine different beta c transcripts were detected, but none was specific for MDS. However, one of the transcripts (beta c79) containing a 79-base intron insertion between exons V and VI was significantly increased in MDS. This 27-kd isoform consisted of the beta c N-terminal 182 amino acids followed by a new 84-amino-acid sequence. beta c79 was overexpressed in all MDS subtypes. No genomic mutations were detected within the intron or at the intron/exon boundaries. The isoform is predominantly located in the cytoplasm by Western blot analysis and was unable to generate high-affinity binding sites or transduce a signal for proliferation when coexpressed with the receptor for human GM-CSF alpha chain. Our study suggests that the accumulation of the abnormal beta c transcripts with intron V retention results in the reduction in cell-surface expression of beta c observed in MDS.

Effect of β-alanyl-L-histidinato zinc on the differentiation of C2C12 cells

Although beta-alanyl-L-histidinato zinc (AHZ) can promote osteoblast differentiation, the molecular mechanism responsible is not fully understood. The purpose of this study was to determine the effect of AHZ on undifferentiating mesenchymal cells. C2C12, a typical pluripotential mesenchymal cell line, was used. The cells were cultured in 5% serum-containing medium to induce differentiation, either with or without the addition of AHZ. Cell lineage was determined by immunostaining of type II myosin heavy chains, alkaline phosphatase (ALPase) activity, mRNA expression of cellular phenotype-specific markers using semi-quantitative reverse transcriptase-polymerase chain reaction, and core binding factor alpha1/runt-related transcription factor-2 (Cbfa1/Runx2) protein synthesis using Western blot analysis. C2C12 cells cultured in the presence of AHZ were strongly inhibited from developing into myoblasts, and showed high ALPase activity that was approximately double that in the vehicle. The expression of mRNA for Cbfa1/Runx2, ALPase, Sox9 and type X collagen was increased markedly by the AHZ-stimulated medium, whereas that of desmin and MyoD mRNA was drastically decreased. AHZ increased Cbfa1/Runx2 protein expression substantially. These results provide clear evidence that AHZ converts the differentiation pathway of C2C12 cells to the osteoblast and/or chondroblast lineage.

The key role of phloroglucinol O-methyltransferase in the biosynthesis of Rosa chinensis volatile 1,3,5-trimethoxybenzene

1,3,5-Trimethoxybenzene is a key component of the Chinese rose odor. This compound is synthesized in three successive methylation steps from phloroglucinol, the initial precursor. A novel, to our knowledge, phloroglucinol O-methyltransferase (POMT) characterized here methylates the first step to produce the intermediate 3,5-dihydroxyanisole, while two previously described orcinol O-methyltransferases catalyze the subsequent steps. We isolated POMT from rose petals and determined partial amino acid sequences of the purified enzyme. The full-length POMT cDNA was isolated and expressed in Escherichia coli. Both the native and recombinant POMT exhibited substrate specificity for phloroglucinol. POMT was expressed specifically in floral organs, in accordance with its role as a key enzyme in the synthesis of rose floral scent compounds.

Impairment of skin wound healing in beta-1,4-galactosyltransferase-deficient mice with reduced leukocyte recruitment

Cell-surface carbohydrate chains are known to contribute to cell migration, interactions, and proliferation, but their roles in skin wound healing have not been evaluated. We examined the biological roles of beta4-galactosylated carbohydrate chains in skin wound healing using mutant mice that lack beta-1,4-galactosyltransferase-I (beta4GalT-I), which is responsible for the biosynthesis of the type 2 chain in N-glycans and the core 2 branch in O-glycans. beta4GalT-I-deficient mice showed significantly delayed wound healing with reduced re-epithelialization, collagen synthesis, and angiogenesis, compared with control mice. Neutrophil and macrophage recruitment at wound sites was also impaired in these mice probably because of selectin-ligand deficiency. In accordance with the reduced leukocyte infiltration, the expression levels of macrophage-derived chemokines, transforming growth factor-beta1, and vascular endothelial growth factor were all reduced in beta4GalT-I(-/-) mice. These results demonstrate that beta4-galactosylated carbohydrate chains play a critical role in skin wound healing by mediating leukocyte infiltration and epidermal cell growth, which affects the production of chemokines and growth factors. This study introduces a suitable mouse model for investigating the molecular mechanisms of skin wound healing and is the first report showing that carbohydrate chains have a strong influence on skin wound healing.

Estrogen regulates the production of VEGF for osteoclast formation and activity in op/op mice

Op/op mice have a severe deficiency of osteoclasts because of lacking functional M-CSF that is an essential factor of osteoclast differentiation and function. We now report that OVX induces osteoclast formation and cures osteopetrosis by increasing the VEGF that regulates osteoclast formation in these mice.

INTRODUCTION

We have found that estrogen deficiency induced by ovariectomy (OVX) upregulated osteoclast formation in op/op mice. We have recently demonstrated that vascular endothelial growth factor (VEGF) could substitute for macrophage colony-stimulating factor (M-CSF) in the support of osteoclastic bone resorption in these mice. Therefore, in this study, we wished to assess the effects of VEGF on bone loss induced by OVX in these mice.

MATERIALS AND METHODS

Eight-week-old op/op mice were bilateral OVX or sham-operated. Mice were killed at 8, 10, and 12 weeks of age, and femurs were removed for preparations. Some OVX mice were treated with three consecutive injections of 120 microl/body of VEGF-neutralizing antibody at 12-h intervals starting from 36 h before death at 4 weeks after OVX. VEGFR-1/Fc chimeric protein (600 microg/kg/day) or 17beta-estradiol (0.16 microg/day) was administered in a dorsal subcutaneous pocket of the mice at the time of OVX. These mice were killed 2 weeks after surgery. Changes of serum levels of VEGF were measured by ELISA. Changes of mRNA levels of VEGF, Flt-1, interleukin-6, and osteoclast differentiation factor (ODF/TRANCE/RANKL) in bone tissue were measured by reverse transcriptase-polymerase chain reaction.

RESULTS

In OVX op/op mice, trabecular bone volume of the femur was decreased, and the number of osteoclasts was significantly increased. Serum levels of VEGF were demonstrated to be higher in OVX mice than in sham-operated mice. VEGF mRNA, Flt-1 mRNA, interleukin-6 mRNA, and RANKL mRNA levels in bone tissue were elevated in OVX mice over that in sham-operated mice. The increase in osteoclast number was inhibited by VEGF antagonist treatment in OVX mice.

CONCLUSIONS

In this study, we have demonstrated that the production of VEGF and RANKL stimulated by OVX results in increased osteoclast formation in op/op mice.

Mechanical stretch induces TGF-beta synthesis in hepatic stellate cells

BACKGROUND

It is known that mechanical stress induces extracellular matrix via transforming growth factor-beta (TGF-beta) synthesis in vascular smooth muscle cells. Activated hepatic stellate cells (HSCs) are an important source of TGF-beta in the liver. However, it remains unclear whether mechanical stress induces TGF-beta in HSCs. The Rho small GTP-binding protein (Rho) has recently emerged as an important regulator of actin and cytoskeleton. We examined whether TGF-beta is expressed in stretched HSCs and whether Rho is involved in stretch-induced TGF-beta synthesis.

MATERIALS AND METHODS

A cultured human HSC cell line, LI90, was used for this study. Hepatic stellate cells were cyclically stretched using the Flexercell(R) strain unit. Concentration of TGF-beta in the conditioned medium was estimated by a bioassay using mink lung epithelial cells transfected with a plasminogen activator inhibitor-1 promoter-luciferase construct. Transforming growth factor-beta mRNA expression of HSCs was estimated by a reverse-transcription polymerase chain reaction. Replication-defective adenoviral vectors expressing a dominant negative type of Rho was utilized to suppress its effect on HSCs.

RESULTS

Transforming growth factor-beta concentration of the conditioned media of stretched HSCs showed time-dependent increases as compared to nonstretched HSCs from 2 h to 24 h. Transforming growth factor-beta mRNA expression in stretched HSCs was increased compared with that in nonstretched HSCs. Transfection of dominant negative Rho inhibited the stretch-induced TGF-beta synthesis.

CONCLUSIONS

Mechanical stretch enhanced TGF-beta expression on mRNA and protein level in HSCs. Rho was closely related to stretch-induced TGF-beta synthesis in HSCs.

Overexpression of CNP in chondrocytes rescues achondroplasia through a MAPK-dependent pathway

Achondroplasia is the most common genetic form of human dwarfism, for which there is presently no effective therapy. C-type natriuretic peptide (CNP) is a newly identified molecule that regulates endochondral bone growth through GC-B, a subtype of particulate guanylyl cyclase. Here we show that targeted overexpression of CNP in chondrocytes counteracts dwarfism in a mouse model of achondroplasia with activated fibroblast growth factor receptor 3 (FGFR-3) in the cartilage. CNP prevented the shortening of achondroplastic bones by correcting the decreased extracellular matrix synthesis in the growth plate through inhibition of the MAPK pathway of FGF signaling. CNP had no effect on the STAT-1 pathway of FGF signaling that mediates the decreased proliferation and the delayed differentiation of achondroplastic chondrocytes. These results demonstrate that activation of the CNP-GC-B system in endochondral bone formation constitutes a new therapeutic strategy for human achondroplasia.

The Endosymbiotie Bacterium Holospora obtusa Enhances Heat-Shock Gene Expression of the Host Paramecium caudatum

The bacterium Holospora obtusa is a macronuclear-specific symbiont of the ciliate Paramecium caudatum. H. obtusa-bearing paramecia could survive even after the cells were quickly heated from 25 degrees C to 35 degrees C. To determine whether infection with H. obtusa confers heat shock resistance on its host, we isolated genes homologous to the heat shock protein genes hsp60 and hsp70 from P. caudatum. The deduced amino acid sequences of both cDNAs were highly homologous to hsp family sequences from other eukaryotes. Competitive PCR showed that H. obtusa-free paramecia expressed only trace amounts of hsp60 and hsp70 mRNA at 25 degrees C, but that expression of hsp70 was enhanced immediately after the cells were transferred to 35 degrees C. H. obtusa-bearing paramecia expressed high levels of hsp7O mRNA even at 25 degrees C and the level was further enhanced when the cells were incubated at 35 degrees C. In contrast, the expression pattern of hsp60 mRNA was the same in H. obtusa-bearing as in H. obtusa-free paramecia. These results indicate that infection with its endosymbiont can confer a heat-shock resistant nature on its host cells.

Time and development

The role that biological timers play in gametogenesis and development is reviewed through use of selected examples. Some general features of biological timers are also reviewed, and two types of timing mechanism are discussed in more detail: circadian rhythms and cell-cycle-based timers. In particular, the recent evidence that oscillatory ion channel activity may play an important role in timing mechanisms is summarized. The activity and properties of an oscillatory K(+) channel present during preimplantation mouse development are described, and preliminary results from its neutralization are discussed.

O6-methylguanine-DNA methyltranspherase gene expression in gliomas by means of real-time quantitative RT-PCR and clinical response to nitrosoureas

O(6)-methylguanine-DNA methyltransferase (MGMT) mRNA expressions were examined in 100 neuroepithelial tumors by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) using SYBR Green I. The mean relative quantitation value of MGMTmRNA normalized to the level of beta2-microglobulin for 100 tumors was 5.3 +/- 11.2. The mean value of 41 glioblastomas was significantly higher than that for the other 59 tumors (p = 0.0008 by Student's t-test). In contrast, the means of 19 low-grade gliomas and 12 medulloblastomas were significantly lower than that of other tumors (p = 0.0282 and p = 0.0456 by Student's t-test). Among the 55 retrospective patients who had been treated with 1-(4-amino-2-methyl-5-pyrimidynyl)methyl-3-(2-chloroethyl)- 3-nitrosourea hydrochloride (ACNU), the value was a significant independent predictor of the effect of initial therapy with ACNU (p = 0.0007 by Mann-Whitney U-test) and the survival period (p = 0.0175 by Wald test). The value >or=1 was the most significant factor in predicting the initial effect of treatment by multi-variant regression analysis (p < 0.0001). These results suggest that our individual adjuvant therapy based on MGMTmRNA expression may be improved by the application of real-time quantitative RT-PCR.

Differentiation in C(2)C(12) myoblasts depends on the expression of endogenous IGFs and not serum depletion

Myogenic differentiation in vitro has been usually viewed as being negatively controlled by serum mitogens. A depletion of critical serum components from medium has been considered to be essential for permanent withdrawal from the cell cycle and terminal differentiation of myoblasts. Removal of serum mitogens induces the expression of insulin-like growth factors (IGFs), whereas it inhibits that of basic fibroblast growth factor (bFGF) and transforming growth factor (TGF)-beta in myoblasts. These responses of growth factors to medium conditioning seem to be well matched to their functions in proliferation/differentiation. In the present study, we showed that C(2)C(12) myoblasts differentiated actively, even in mitogen-rich medium, and that this medium offered an advantage over mitogen-poor medium in terms of increasing differentiation. Our attention focused on endogenous growth factors, as described above, especially IGFs in mitogen-rich medium. During differentiation, IGF-I and IGF-II mRNA levels increased, but bFGF and TGF-beta(1) mRNAs decreased. Differentiation was commensurable with IGF mRNA levels and suppressed by antisense oligodeoxynucleotides and neutralizing monoclonal antibodies against IGFs. These results suggest that an autocrine/paracrine loop of IGFs, bFGF, and TGF-beta(1) is active in proliferating and differentiating C(2)C(12) cells without a depletion of serum and that endogenous IGFs actively override the negative control of differentiation by serum mitogens.

Differentiating embryonic stem cells: GAPDH, but neither HPRT nor beta-tubulin is suitable as an internal standard for measuring RNA levels

Embryonic stem (ES) cells are pluripotent cell lines that possess virtually unlimited self-renewal and differentiation capacity. Such characteristics make them potentially an invaluable cell source for diverse tissue-engineering applications. In vitro ES cell differentiation occurs spontaneously in three-dimensional structures termed "embryoid bodies" that mimic postimplantation embryonic tissue. HPRT, beta-tubulin, and GAPDH are commonly used as internal RNA standards in ES cell-derived gene transcription studies so that corrected sample mRNA levels can be obtained for (semi) quantitative gene expression data. However, if reliable data is to be obtained, it is essential that such housekeeping gene expression remains constant, and this has not been demonstrated for differentiating ES cell cultures, which represent a mixed and changing population of cells with time in culture. Therefore, in the present study, we tested the suitability of these housekeeping genes to act as true internal standards for differentiating murine ES cells cultured as embryoid bodies. PCR-amplified gene-specific products were quantified from digital images of ethidium bromide-stained gels using a computer software package. Both HPRT and beta-tubulin mRNA levels varied markedly in spontaneously differentiating and growth factor-supplemented (TGF-beta) ES cell cultures (p < 0.001, ANOVA), while GAPDH expression remained relatively constant (p > 0.2). Our results demonstrate the importance of fully validating housekeeping gene expression in in vitro ES cell gene transcription studies and suggest that GAPDH may be a suitable candidate to act as an internal RNA standard, while both HPRT and beta-tubulin appear to be inappropriate. Finally, we demonstrate enhanced mesodermal differentiation of ES cell-derived cultures by treatment with TGF-beta through significant upregulation of Brachyury T expression, with a concomitant decrease in expression of the undifferentiated ES cell marker Oct-4.

Accelerated wound healing in tumor necrosis factor receptor p55-deficient mice with reduced leukocyte infiltration

To clarify biological roles of tumor necrosis factor receptor p55 (TNF-Rp55) -mediated signals in wound healing, skin excisions were prepared in BALB/c (WT) and TNF-Rp55-deficient (KO) mice. In WT mice, the wound area was reduced to 50% of the original area 6 days after injury, with angiogenesis and collagen accumulation. Histopathologically, reepithelialization rate was approximately 80% 6 days. Myeloperoxidase activity and macrophage recruitment were the most evident 1 and 6 days after injury, respectively. Gene expression of adhesion molecules, interleukin 1alpha (IL-1alpha), IL-1beta, monocyte chemoattractant protein 1, macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-2, transforming growth factor beta1 (TGF-beta1) connective tissue growth factor (CTGF), vascular endothelial growth factor (VEGF), Flt-1, and Flk-1 was enhanced at the wound site. In KO mice, an enhancement in angiogenesis, collagen content, and reepithelialization was accelerated with the increased gene expression of TGF-beta1, CTGF, VEGF, Flt-1, and Flk-1 at the wound sites, resulting in accelerated wound healing compared with WT mice. In contrast, leukocyte infiltration, mRNA expression of adhesion molecules, and cytokines were significantly reduced in KO mice. These observations suggest that TNF-Rp55-mediated signals have some role in promoting leukocyte infiltration at the wound site and negatively affect wound healing, probably by reducing angiogenesis and collagen accumulation.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on preimplantation mouse embryos

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent environmental contaminant that can exert developmental toxicity. To investigate the stage-specific effects of TCDD on preimplantation embryos, we exposed mouse embryos to TCDD at different stages (1-, 2-, and 8-cell) and collected them at different stages of development (the 1- or 2-, 8-cell, and blastocyst stage, respectively). Semiquantitative RT-PCR revealed increased constitutive gene expression of the arylhydrocarbon receptor (AhR) and AhR nuclear translocator (Arnt) at the 1-cell stage, decreased expression at the 2- to 8-cell stage, and increased expression again at the blastocyst stage, and addition of TCDD to media did not affect their mRNA levels. Interestingly, no cytochrome P4501A1 (CYP1A1) mRNA was detected in embryos at the 1-, 2-, and 8-cell stages after exposure to 10 nM TCDD for 12 or 24 h, whereas CYP1A1 mRNA was significantly increased at the blastocyst stage in response to TCDD, and its induction was found to be concentration-dependent on TCDD exposure from 0.01 to 10 nM for 24 h. In addition, no significant differences in development rate of preimplantation embryos, cell number of blastocyst embryos, or apoptotic indices, such as TUNEL-positive cell number or Bax/Bcl-2 expression ratios were observed at the blastocyst stage between TCDD-exposed groups and non-exposed group. These results suggest that the sensitivity to TCDD differs with the embryonic stage, which may reflect an ability of embryos to adapt to environmental stressors, such as dioxins.

Differential expression of matrix metalloproteinases 2 and 9 by glial Müller cells: response to soluble and extracellular matrix-bound tumor necrosis factor-alpha

Glial Müller cells are known to undergo functional and morphological changes during retinal proliferative disorders, but very little is known of the contribution of these cells to extracellular matrix deposition during retinal wound healing and gliosis. This study constitutes the first demonstration that retinal Müller cells express two major matrix metalloproteinases (MMPs), gelatinase A (MMP-2) and gelatinase B (MMP-9), implicated in cell migration and matrix degradation. Although mRNA and gelatinolytic activity of MMP-2 remained unchanged in cultured Müller cells, basal levels of MMP-9 mRNA observed after subculture at 24 hours, markedly declined after 48 or 72 hours. This correlated with the expression of MMP-9 gelatinolytic activity that peaked at 24 hours, but gradually decreased at 48 and 72 hours. Tumor necrosis factor-alpha, in both a soluble form or bound to collagen and fibronectin, increased MMP-9 mRNA and gelatinolytic activity, but not MMP-2 expression, and its effect could be blocked by anti-tumor necrosis factor-alpha antibodies. The results suggest that Müller cells may aid in the local control of extracellular matrix deposition during retinal proliferative disorders, and that interaction of these cells with matrix-bound cytokine may influence their pathological behavior. Control of Müller cell production of MMP-9 may constitute an important target for the design of new therapeutic approaches to treat and prevent retinal proliferative disease.

Interleukin-1alpha enhances type I collagen-induced activation of matrix metalloproteinase-2 in odontogenic keratocyst fibroblasts

Interleukin-1alpha (IL-1alpha) is strongly expressed in odontogenic keratocysts. In this study, we investigated the effects of IL-1alpha on the activation of matrix metalloproteinase-2 (MMP-2) in the fibroblasts isolated from odontogenic keratocysts. Odontogenic keratocyst fibroblasts secreted a latent form of MMP-2 (proMMP-2) spontaneously. Type I collagen induced the activation of the proMMP-2, and recombinant human IL-1alpha (rhIL-1alpha) further enhanced the type I collagen-induced activation of proMMP-2 in a dose-dependent manner. The rhIL-1alpha-induced activation of proMMP-2 was inhibited by anti-human IL-1alpha antibody. A reverse-transcription/polymerase chain-reaction (RT-PCR) and Western immunoblotting demonstrated that the expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) mRNA and protein was increased in the fibroblasts when the cells were cultured on type I collagen, and the expression was further enhanced by rhIL-1alpha. Thus, IL-1alpha may up-regulate proMMP-2 activation by increasing the expression of MT1-MMP in the fibroblasts isolated from odontogenic keratocysts synergistically with type I collagen.

Mechanism of AVP release and synthesis in chronic salt-loaded rats

Arginine vasopressin (AVP) is involved in osmotic regulation in the brain and peripheral tissues. To elucidate the regulatory mechanism that involves AVP release in hyperosmolality, we investigated the regulation of the synthesis and release of AVP in chronic salt-loaded rats. In chronic salt-loaded rats, which were generated by free access to water containing 2% NaCl for 7 days, plasma osmolality was significantly increased compared with control value. When tested, the AVP content was significantly higher in plasma but lower in the pituitary and whole brain (hypothalamus, cortex and striatum) than in control rats. The expression of AVP mRNA in the brain was significantly up-regulated compared with that in control rats. These data lead to the suggestion that hyperosmolality stimulates AVP release from the brain and subsequently induces AVP synthesis in the brain. On the other hand, mRNA levels of vasopressin V1a receptor (V1aR), whose down-regulation is known to be a counteraction to the V1aR activation, was not changed in the brain, suggesting that the AVP seems not to interact with the V1aR in the brain. These results suggest that hyperosmosis promotes the release of AVP into plasma, the subsequent induction of AVP mRNA in the brain and its action on the peripheral tissues.

Pitavastatin enhanced BMP-2 and osteocalcin expression by inhibition of Rho-associated kinase in human osteoblasts

To clarify the mechanism of the stimulatory effect of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on bone formation, we investigated the effect of pitavastatin, a newly developed statin, on expression of bone morphogenetic protein-2 (BMP-2) and osteocalcin in primary cultured human osteoblasts. Pitavastatin increased the expression level of mRNA for BMP-2, and much more effectively for osteocalcin. This stimulatory effect was abolished by the addition of geranylgeranyl pyrophosphate, an essential molecule for prenylation of small GTP-binding proteins such as Rho GTPase, but not by inhibitors of nitric oxide synthase and various protein kinases. Pitavastatin suppressed the Rho-associated kinase (Rho-kinase) activity. Hydroxyfasudil, a specific inhibitor of Rho-kinase, increased BMP-2 and osteocalcin expression. These mRNA levels were strongly suppressed by dexamethasone, but restored by co-treatment with hydroxyfasudil. These observations suggest that the Rho-kinase negatively regulates bone formation and the inhibition of Rho and Rho-kinase pathway is the major mechanism of the statin effect on bone. Moreover, a Rho-kinase inhibitor may be a new therapeutic reagent for the treatment of osteoporosis such as glucocorticoid-induced osteoporosis.

Role of the Fas system in liver regeneration after a partial hepatectomy in rats

Apoptosis is involved in the homeostatic control of organs. The aim of this study was to define the in vivo role of apoptosis-related proteins including the Fas system and Bcl-2 in liver regeneration following a partial hepatectomy (PH). We used 70% hepatectomized rats which were serially sacrificed from 12 h to 28 days. The expressions of Fas, Fas ligand, and Bcl-2 were examined by semiquantitative RT-PCR and immunohistochemistry. Liver regeneration, as examined by PCNA staining, peaked from 24 h to day 3, and declined from day 5. On the other hand, hepatocyte apoptosis, as examined by TUNEL staining, was seldom observed until 24 h, but increased from 1 week after PH. In the RT-PCR study, Fas showed an early decline by 24 h, followed by a later peak from days 3 to 5, and then a constant expression thereafter. Meanwhile, the Fas ligand was also low until day 3, but showed a remarkable increase from days 5 to 7, followed by a gradual decrease. On the other hand, Bcl-2 showed an early peak until 24 h, followed by a decline from day 5. In an immunohistochemical study, the time courses of these protein expressions were almost synchronous with their mRNAs in the RT-PCR study. We thus conclude that the coordinated interplay between these apoptosis-related proteins and hepatocyte apoptosis suggests the possible involvement of these proteins in the course of liver regeneration.

The maternal legacy to the embryo: cytoplasmic components and their effects on early development

RNA molecules and proteins are accumulated in the oocyte cytoplasm during its growth phase and are used to sustain the early phases of embryonic development before embryo DNA transcription begins. This makes the oocyte a very special cell, quite different from somatic cells where RNA and proteins usually undergo a rapid turnover. To enable the storage and timely use of such stored molecules, various mechanisms are effective in the oocyte and are gradually being elucidated. Our understanding of such mechanisms is important for constantly improving therapy for human and animal reproductive disorders as well as for understanding the process of nuclear reprogramming during cloning procedure or stem cell generation. This review focuses on the various aspects of these regulatory processes in an attempt to give an overview of the present knowledge on post-transcriptional and post-translational mechanisms taking place during oocyte maturation and early development. Mechanisms such as cytoplasmic regulation of the poly(A) tail, RNA localization and protein phosphorylation are described in some detail. Because most data are available from lower species these are presented together with appropriate reference to the mammalian oocyte when data are known, or when important differences have been described.

Alternation of inwardly rectifying background K+ channel during development of rat fetal cardiomyocytes

The resting membrane potential of rat ventricular myocytes dramatically hyperpolarizes in the late phase of the fetal period. In order to investigate the mechanisms of this hyperpolarization, we examined the electrophysiological properties and molecular structure of the inwardly rectifying background K+ channels of rat fetal ventricular myocytes. In a patch-clamp experiment the whole-cell current of the inwardly rectifying background K+ channel increased 12-fold from between 12 and 18 days after impregnation. In the single channel recording, the large-conductance (35 pS) channels were mainly observed in the 18-day fetal ventricular myocytes. In the 12-day cells, the large-conductance channel was not observed although the low-conductance channels (11 and 16 pS) were infrequently observed. These data of single channel recordings suggested that channel proteins conducting the inwardly rectifying background K+ current were altered during the fetal development. Therefore, we compared the expression of Kir 2.1 mRNA and Kir 2.2 mRNA between 12 days and 18 days using the RT-PCR method, in order to investigate the possible molecular regulation which contributes to the electrophysiological changes. During the fetal period, the expression of Kir 2.2 mRNA increased tremendously (17 times), whereas the increase in the expression of Kir 2.1 mRNA (two times) was not so great. These results show that hyperpolarization in the late fetal period seems to be mainly due to the dramatic increase in expression of Kir 2.2 mRNA rather than expression of Kir 2.1 mRNA.

Stimulation of melanogenesis in murine melanoma cells by 2-mercapto-1-(beta-4-pyridethyl) benzimidazole (MPB)

The effects of 2-mercapto-1-(beta-4-pyridethyl) benzimidazole (MPB), one of the benzimidazole derivatives designed for a nucleic acid analogue, on melanogenesis of murine B16-F10 melanoma cell lines were investigated. MPB (40 microM) induced a striking dendricity in B16 melanoma cells within 12 h and maximal dendricity between 48 and 72 h. The stimulation of melanin synthesis was observed after only 2 days of treatment together with a dose-dependent growth inhibition. Moreover, MPB increased the activity of tyrosinase through the expression of tyrosinase mRNA without increasing the intracellular cyclic AMP content. MPB-induced melanogenesis was inhibited by novel protein kinase A inhibitors, KT-5720 and H-85. These findings indicate that MPB stimulated B16 cells to terminally differentiate and may be a useful drug in studying the regulation of melanogenesis.

Regulation of early chicken thymocyte proliferation by transforming growth factor-beta from thymic stromal cells and thymocytes

We examined expression of TGF-betas in chicken thymic stromal cells and thymocytes and roles of TGF-betas in thymocyte development within the thymus. Thymic stromal cells expressed TGF-beta 2 and 3 genes but not TGF-beta 4 gene. Thymocytes showed expressions of TGF-beta 2, 3 and 4 genes and each TGF-beta gene was expressed more strongly in CD3- than CD3+ thymocytes. When anti-TGF-beta antibody was added with supernatants of stromal cells into thymocyte culture, only proliferative activity of CD3- thymocytes was enhanced and the cells in S and G2/M compartments of cell cycle increased. These results suggest that TGF-beta which is expressed in the thymus may regulate the ability of immature thymocytes to progress through the cell cycle and to differentiate to CD3+ thymocytes.

Early development of mouse embryos null mutant for the cyclin A2 gene occurs in the absence of maternally derived cyclin A2 gene products

Progression through the mammalian cell cycle is regulated by the sequential activation and inactivation of the cyclin-dependent kinases. In adult cells, cyclin A2-dependent kinases are required for entry into S and M phases, completion of S phase, and centrosome duplication. However, mouse embryos lacking the cyclin A2 gene nonetheless complete preimplantation development, but die soon after implantation. In this report, we investigated whether a contribution of maternal cyclin A2 mRNA and protein to early embryonic cell cycles might explain these conflicting observations. Our data show that a maternal stock of cyclin A2 mRNA is present in the oocyte and persists after fertilization until the second mitotic cell cycle, when it is degraded to undetectable levels coincident with transcriptional activation of the zygotic genome. A portion of maternally derived cyclin A2 protein is stable during the first mitosis and persists in the cytoplasm, but is completely degraded at the second mitosis. The ability of cyclin A2-null mutants to develop normally from the four-cell to the postimplantation stage in the absence of detectable cyclin A2 gene product indicates therefore that cyclin A2 is dispensable for cellular progression during the preimplantation nongrowth period of mouse embryo development.

Underexpression of neural cell adhesion molecule and neurotrophic factors in rat brain following thromboxane A(2)-induced intrauterine growth retardation

Intrauterine growth retardation (IUGR) often results in clinical neurodevelopmental disorders. To clarify the influence of uteroplacental insufficiency on central nervous system development, we have created a model of IUGR in rats using maternal administration of synthetic thromboxane A(2). We investigated expression patterns of neural cell adhesion molecule (NCAM) and reelin in this model by semiquantitative competitive polymerase chain reactions. On postnatal day 2, NCAM expression was decreased in rat cerebral cortex, and reelin expression was decreased in hippocampus from levels in controls without maternal thromboxane exposure. No significant differences in NCAM expression were seen in hippocampus, nor did reelin expression differ in cerebral cortex between control and IUGR groups. We also examined expression of two neurotrophic factors, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). In cerebral cortex the IUGR group showed less BDNF and NT-3 expression than controls. Delay of neuronal migration and histological changes observed in our IUGR rats may be related to altered expression of these molecules.

Apolipoprotein E inhibition of vascular smooth muscle cell proliferation but not the inhibition of migration is mediated through activation of inducible nitric oxide synthase

Initial experiments revealed that low concentrations of apolipoprotein (apo) E (0.1 to 5 microg/mL) were effective in inhibiting platelet-derived growth factor (PDGF)-directed smooth muscle cell (SMC) migration by 60% to 80%. In contrast, higher concentrations of apoE, at 25 and 50 microg/mL, were necessary to achieve similar inhibition of PDGF-induced SMC proliferation. The potential role of nitric oxide (NO) in mediating the inhibitory effects of apoE was explored. Results showed that, although 0.1 to 5 microg/mL of apoE had no effect on NO production by SMCs, physiological concentrations of apoE (25 to 50 microg/mL) enhanced NO synthesis by 2-fold in a dose-dependent manner (P<0.001). Reverse transcription-polymerase chain reaction amplification of RNA obtained from control and apoE-treated SMCs demonstrated a direct role of apoE in activating inducible nitric oxide synthase (iNOS) gene expression. The apoE-induced nitric oxide production was significantly reduced by coincubation of the cells with aminoguanidine or N(G)-monomethyl-L-arginine (P<0.05) or with antisense iNOS oligodeoxynucleotides (P<0.01). Moreover, the inhibition of iNOS was shown to overcome apoE suppression of PDGF-induced vascular SMC proliferation. However, apoE suppression of PDGF-directed SMC migration was not affected by these treatments. Taken together, these results document that apoE exerts its inhibitory effects on cell proliferation via activation of iNOS. However, apoE inhibition of cell migration is mediated by a mechanism independent of iNOS activation.

Age-related changes of gene expression in mouse kidney: fluorescence differential display--PCR analyses

We used a fluorescence differential display--PCR (FDD-PCR) technique to analyze the genes expressed in mouse kidneys collected at nine different developmental stages ranging from 3 days to 15 months after birth. We found ten genes that were age-dependent and differentially-expressed in the kidneys during our experimental period. We confirmed by comparative RT-PCR that of the ten cDNAs, seven showed reproducible age-dependent expression. Four of the nucleotide sequences of these cDNA clones, had high homology with known genes (fibronectin, soluble guanylyl cyclase alpha-1 subunit, cytosolic aldehyde dehydrogenase and mitochondrial DNA), and three with expressed sequence tags of unknown genes. The FDD-PCR method was very useful for detecting new age-related genes expressed differentially in the mouse kidney.