Effectiveness of novel oral hygiene instruction avoiding inattentional blindness using an application for unique plaque control record calculation: A randomized clinical trial

OBJECTIVE

This study was performed to estimate the effectiveness of novel oral hygiene instruction (OHI) focusing on areas with deep periodontal pockets for reduction of periodontal inflammation.

BACKGROUND DATA DISCUSSING THE PRESENT STATUS OF THE FIELD

Because stained areas on the plaque chart do not always correspond to the areas with deep periodontal pockets, conventional OHI based on O'Leary's plaque control record (PCR) often provides guidance inconsistent with the target area.

METHODS

This randomized clinical trial involved two groups: (1) OHI based on the PCR limited in deep pocket sites (novel OHI group) and (2) OHI based on O'Leary's PCR (conventional OHI group). The unique PCR (aggressive target for PCR [agPCR]; only counting the plaque-stained areas with PD at ≥4 mm sites) for the novel OHI was calculate by dedicated expression program. The probing depth (PD), bleeding on probing (BOP), and periodontal inflamed surface area (PISA) were obtained at the baseline and 5 to 6 months later.

RESULTS

The approximation curve with PISA before and after instruction indicated that the PISA converged to a lower value after instruction in the novel OHI group. The approximation curve with the improvement rate of the PISA and agPCR showed a positive correlation in the novel OHI group but no correlation in the conventional OHI group.

CONCLUSION

Control of inflammation was more effective in the novel OHI group. These results suggest that this novel OHI technique using our developed application could be used as a strategy to improve the effectiveness of brushing instruction.

Suppression of subgingival bacteria by antimicrobial photodynamic therapy using transgingival irradiation: A randomized clinical trial

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) is an effective method for eradicating bacteria in periodontal therapy. Standard aPDT requires the insertion of a laser tip into a periodontal pocket, in which the direction of irradiation is limited. Therefore, we devised an aPDT method that uses a transgingival near-infrared wavelength and indocyanine green-encapsulated and chitosan-coated nanoparticles as a photosensitizer.

METHODS

Forty patients undergoing supportive periodontal therapy, who had a single root tooth with a pocket of 5 mm or deeper, were used as subjects. In the test group, aPDT was performed by laser irradiation from outside the gingiva using photosensitizer nanoparticles. In the control group, pseudo aPDT without photosensitizer was performed by transgingival irradiation. Subgingival plaque was sampled from inside the pocket before, immediately after, and 1 week after treatment, and evaluated by colony counting and real-time polymerase chain reaction.

RESULTS

There were no significant differences in age, sex, periodontal pocket depth, and bleeding on probing between the test and control groups. Compared with the colony count before treatment, the count in the test group was significantly reduced immediately after treatment. The number of patients with colony reduction to ≤50% and ≤10% was significantly higher in the test group than in the control group. None of the participants reported pain, although one participant reported discomfort.

CONCLUSION

As a bacterial control method for residual pockets in patients undergoing supportive periodontal therapy, transgingival aPDT is a promising treatment strategy that is not generally accompanied by pain or discomfort.

OP0112 THE EVER-LARGEST ASIAN GWAS FOR SYSTEMIC SCLEROSIS AND TRANS-POPULATION META-ANALYSIS IDENTIFIED SEVEN NOVEL LOCI AND A CANDIDATE CAUSAL SNP IN A CIS-REGULATORY ELEMENT OF THE FCGR REGION

Background

Genome-wide association studies (GWASs) have identified 29 disease-associated single nucleotide polymorphisms (SNPs) for systemic sclerosis (SSc) in non-human leukocyte antigen (HLA) regions (1-7). While these GWASs have clarified genetic architectures of SSc, study subjects were mainly Caucasians limiting application of the findings to Asians.

Objectives

The study was conducted to identify novel causal variants for SSc specific to Japanese subjects as well as those shared with European population. We also aimed to clarify mechanistic effects of the variants on pathogenesis of SSc.

Methods

A total of 114,108 subjects comprising 1,499 cases and 112,609 controls were enrolled in the two-staged study leading to the ever-largest Asian GWAS for SSc. After applying a strict quality control both for genotype and samples, imputation was conducted using the reference panel of the phase 3v5 1,000 genome project data combined with a high-depth whole-genome sequence data of 3,256 Japanese subjects. We conducted logistic regression analyses and also combined the Japanese GWAS results with those of Europeans (6) by an inverse-variance fixed-effect model. Polygenicity and enrichment of functional annotations were evaluated by linkage disequilibrium score regression (LDSC), Haploreg and IMPACT programs. We also constructed polygenic risk score (PRS) to predict SSc development.

Results

We identified three (FCRLA-FCGR, TNFAIP3, PLD4) and four (EOMES, ESR1, SLC12A5, TPI1P2) novel loci in Japanese GWAS and a trans-population meta-analysis, respectively. One of Japanese novel risk SNPs, rs6697139, located within FCGR gene clusters had a strong effect size (OR 2.05, P=4.9×10-11). We also found the complete LD variant, rs10917688, was positioned in cis-regulatory element and binding motif for an immunomodulatory transcription factor IRF8 in B cells, another genome-wide significant locus in our trans-ethnic meta-analysis and the previous European GWAS. Notably, the association of risk allele of rs10917688 was significant only in the presence of the risk allele of the IRF8. Intriguingly, rs10917688 was annotated as one enhancer-related histone marks, H3K4me1, in B cells, implying that FCGR gene(s) in B cells may play an important role in the pathogenesis of SSc. Furhtermore, significant heritability enrichment of active histone marks and a transcription factor C-Myc were found in B cells both in European and Japanese populations by LDSC and IMPACT, highlighting a possibility of a shared disease mechanism where abnormal B-cell activation may be one of the key drivers for the disease development. Finally, PRS using effects sizes of European GWAS moderately fit in the development of Japanese SSc (AUC 0.593), paving a path to personalized medicine for SSc.

Conclusion

Our study identified seven novel susceptibility loci in SSc. Downstream analyses highlighted a novel disease mechanism of SSc where an interactive role of FCGR gene(s) and IRF8 may accelerate the disease development and B cells may play a key role on the pathogenesis of SSc.

References

[1]F. C. Arnett et al. Ann Rheum Dis, 2010.

[2]T. R. Radstake et al. Nat Genet, 2010.

[3]Y. Allanore et al. PLoS Genet, 2011.

[4]O. Gorlova et al. PLoS Genet, 2011.

[5]C. Terao et al. Ann Rheum Dis, 2017.

[6]E. López-Isac et al. Nat Commun, 2019.

[7]W. Pu et al. J Invest Dermatol, 2021.

Disclosure of Interests

None declared

Photodynamic Inactivation of an Endodontic Bacteria Using Diode Laser and Indocyanine Green-Loaded Nanosphere

Apical periodontitis, an inflammatory lesion causing bone resorption around the apex of teeth, is treated by eradicating infectious bacteria from the root canal. However, it has a high recurrence rate and often requires retreatment. We investigated the bactericidal effect of antimicrobial photodynamic therapy (aPDT)/photodynamic antimicrobial chemotherapy (PACT) using indocyanine green (ICG)-loaded nanospheres coated with chitosan and a diode laser on a biofilm of Enterococcus faecalis, a pathogen of refractory apical periodontitis. Biofilm of E. faecalis was cultured in a porcine infected root canal model. ICG solution was injected into the root canal, which was then irradiated with a laser (810 nm wavelength) from outside the root canal. The bactericidal effect was evaluated by colony counts and scanning electron microscopy. The result of the colony counts showed a maximum 1.89 log reduction after irradiation at 2.1 W for 5 min. The temperature rise during aPDT/PACT was confirmed to be within a safe range. Furthermore, the light energy transmittance through the root was at a peak approximately 1 min after the start of irradiation, indicating that most of the ICG in the root canal was consumed. This study shows that aPDT/PACT can suppress E. faecalis in infected root canals with high efficiency.

Angiopoietin-like protein 2 regulates Porphyromonas gingivalis lipopolysaccharide-induced inflammatory response in human gingival epithelial cells

Angiopoietin-like protein 2 (ANGPTL2) maintains tissue homeostasis by inducing inflammation and angiogenesis. It is produced in infiltrating immune cells or resident cells, such as adipocytes, vascular endothelial cells, and tumor cells. We hypothesized that ANGPTL2 might play an important role as a unique mediator in both systemic and periodontal disease. We demonstrated an increased ANGPTL2 concentration in gingival crevicular fluid from chronic periodontitis patients. Porphyromonas gingivalis lipopolysaccharide (LPS) treatment strongly induced ANGPTL2 mRNA and protein levels in Ca9-22 human gingival epithelial cells. Recombinant human ANGPTL2 increased interleukin 1β (IL-1β), IL-8, and tumor necrosis factor-α (TNF-α) mRNA and protein levels in Ca9-22 cells. Small-interfering (si)RNA-mediated ANGPTL2 knockdown in Ca9-22 cells reduced IL-1β, IL-8 and TNF-α mRNA and protein levels compared with control siRNA (p<0.01) in P. gingivalis LPS-stimulated Ca9-22 cells. Antibodies against integrin α5β1, an ANGPTL receptor, blocked induction of these inflammatory cytokines in P. gingivalis LPS-treated Ca9-22 cells, suggesting that secreted ANGPTL induces inflammatory cytokines in gingival epithelial cells via an autocrine loop. The classic sequential cascade of P. gingivalis LPS → inflammatory cytokine induction is well established. However, in the current study, we reveal a novel cascade comprising sequential P. gingivalis LPS → ANGPTL2 → integrin α5β1 → inflammatory cytokine induction, which might be responsible for inducing potent periodontal disorganization activity in gingival epithelial cells. Via this pathway, ANGPTL2 functions in the pathogenesis of periodontitis and contributes to prolonging chronic inflammation in patients with systemic disease.

F-spondin negatively regulates dental follicle differentiation through the inhibition of TGF-β activity

OBJECTIVE

F-spondin is an extracellular matrix (ECM) protein that belongs to the thrombospondin type I repeat superfamily and is a negative regulator of bone mass. We have previously shown that f-spondin is specifically expressed in the dental follicle (DF), which gives rise to the periodontal ligament (PDL) during the tooth root formation stage. To investigate the molecular mechanism of PDL formation, we investigated the function of f-spondin in DF differentiation.

DESIGN

The expression patterning of f-spondin in the developing tooth germ was compared with that of periodontal ligament-related genes, including runx2, type I collagen and periostin, by in situ hybridization analysis. To investigate the function of f-spondin during periodontal ligament formation, an f-spondin adenovirus was infected into the bell stage of the developing tooth germ, and the effect on dental differentiation was analyzed.

RESULTS

F-spondin was specifically expressed in the DF of the developing tooth germ; by contrast, type I collagen, runx2 and periostin were expressed in the DF and in the alveolar bone. F-spondin-overexpresssing tooth germ exhibited a reduction in gene expression of periostin and type I collagen in the DF. By contrast, the knockdown of f-spondin in primary DF cells increased the expression of these genes. Treatment with recombinant f-spondin protein functionally inhibited periostin expression induced by transforming growth factor-β (TGF-β).

CONCLUSION

Our data indicated that f-spondin inhibits the differentiation of DF cells into periodontal ligament cells by inhibiting TGF-β. These data suggested that f-spondin negatively regulates PDL differentiation which may play an important role in the immature phenotype of DF.

New Irradiation Method with Indocyanine Green-Loaded Nanospheres for Inactivating Periodontal Pathogens

Antimicrobial photodynamic therapy (aPDT) has been proposed as an adjunctive strategy for periodontitis treatments. However, use of aPDT for periodontal treatment is complicated by the difficulty in accessing morphologically complex lesions such as furcation involvement, which the irradiation beam (which is targeted parallel to the tooth axis into the periodontal pocket) cannot access directly. The aim of this study was to validate a modified aPDT method that photosensitizes indocyanine green-loaded nanospheres through the gingivae from outside the pocket using a diode laser. To establish this trans-gingival irradiation method, we built an in vitro aPDT model using a substitution for gingivae. Irradiation conditions and the cooling method were optimized before the bactericidal effects on Porphyromonas gingivalis were investigated. The permeable energy through the gingival model at irradiation conditions of 2 W output power in a 50% duty cycle was comparable with the transmitted energy of conventional irradiation. Intermittent irradiation with air cooling limited the temperature increase in the gingival model to 2.75 °C. The aPDT group showed significant bactericidal effects, with reductions in colony-forming units of 99.99% after 5 min of irradiation. This effect of aPDT against a periodontal pathogen demonstrates the validity of trans-gingival irradiation for periodontal treatment.

Periodontal tissue engineering by nano beta-tricalcium phosphate scaffold and fibroblast growth factor-2 in one-wall infrabony defects of dogs

BACKGROUND AND OBJECTIVE

Nanoparticle bioceramics are being investigated for biomedical applications. We fabricated a regenerative scaffold comprising type I collagen and beta-tricalcium phosphate (β-TCP) nanoparticles. Fibroblast growth factor-2 (FGF-2) is a bioeffective signaling molecule that stimulates cell proliferation and wound healing. This study examined the effects, on bioactivity, of a nano-β-TCP/collagen scaffold loaded with FGF-2, particularly on periodontal tissue wound healing.

MATERIAL AND METHODS

Beta-tricalcium phosphate was pulverized into nanosize particles (84 nm) and was then dispersed. A nano-β-TCP scaffold was prepared by coating the surface of a collagen scaffold with a nanosize β-TCP dispersion. Scaffolds were characterized using scanning electron microscopy, compressive testing, cell seeding and rat subcutaneous implant testing. Then, nano-β-TCP scaffold, nano-β-TCP scaffold loaded with FGF-2 and noncoated collagen scaffold were implanted into a dog one-wall infrabony defect model. Histological observations were made at 10 d and 4 wk postsurgery.

RESULTS

Scanning electron microscopy images show that TCP nanoparticles were attached to collagen fibers. The nano-β-TCP scaffold showed higher compressive strength and cytocompatibility compared with the noncoated collagen scaffold. Rat subcutaneous implant tests showed that the DNA contents of infiltrating cells in the nano-β-TCP scaffold and the FGF-2-loaded scaffold were approximately 2.8-fold and 3.7-fold greater, respectively, than in the collagen scaffold. Histological samples from the periodontal defect model showed about five-fold greater periodontal tissue repair following implantation of the nano-β-TCP scaffold loaded with FGF-2 compared with the collagen scaffold.

CONCLUSION

The β-TCP nanoparticle coating strongly improved the collagen scaffold bioactivity. Nano-β-TCP scaffolds containing FGF-2 are anticipated for use in periodontal tissue engineering.

Isolation and characterization of the human immature osteoblast culture system from the alveolar bones of aged donors for bone regeneration therapy

BACKGROUND

Establishment of human osteoblast cultures that retain bone-forming capacity is one of the prerequisites for successful bone regeneration therapy. Because osteoblasts harvested from adults exhibit limited growth, the use of immature osteoblasts that can expand ex vivo should greatly facilitate bone regeneration therapy. In this study, we developed immature human osteoblasts isolated from aged alveolar bone (HAOBs).

METHODS

HAOBs obtained after the collagenase digestion of alveolar bones from elderly donors. Then, we assessed osteogenic ability of HAOB after treatment with recombinant human bone morphogenic protein-2 or transplantation into immunodeficient mice. In addition, we performed global gene expression analysis to identify functional marker for HAOB.

RESULTS

HAOBs, which can differentiate into osteoblasts and have a robust bone-forming ability, were successfully extracted from donors who were > 60 years of age. We found that the HAOBs exhibited a higher osteogenic ability compared with those of human mesenchymal stem cells and highly expressed NEBULETTE (NEBL) with osteogenic abilities.

CONCLUSIONS

HAOBs have properties similar to those of human immature osteoblasts and appear to be a novel material for cell-based bone regeneration therapy. Additionally, the expression level of NEBL may serve as a marker for the osteogenic ability of these cells.

Bone augmentation using a highly porous PLGA/β-TCP scaffold containing fibroblast growth factor-2

BACKGROUND AND OBJECTIVE

Beta-tricalcium phosphate (β-TCP), a bio-absorbable ceramic, facilitates bone conductivity. We constructed a highly porous three-dimensional scaffold, using β-TCP, for bone tissue engineering and coated it with co-poly lactic acid/glycolic acid (PLGA) to improve the mechanical strength and biological performance. The aim of this study was to examine the effect of implantation of the PLGA/β-TCP scaffold loaded with fibroblast growth factor-2 (FGF-2) on bone augmentation.

MATERIAL AND METHODS

The β-TCP scaffold was fabricated by the replica method using polyurethane foam, then coated with PLGA. The PLGA/β-TCP scaffold was characterized by scanning electron miscroscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, compressive testing, cell culture and a subcutaneous implant test. Subsequently, a bone-forming test was performed using 52 rats. The β-TCP scaffold, PLGA-coated scaffold, and β-TCP and PLGA-coated scaffolds loaded with FGF-2, were implanted into rat cranial bone. Histological observations were made at 10 and 35 d postsurgery.

RESULTS

SEM and TEM observations showed a thin PLGA layer on the β-TCP particles after coating. High porosity (> 90%) of the scaffold was exhibited after PLGA coating, and the compressive strength of the PLGA/β-TCP scaffold was six-fold greater than that of the noncoated scaffold. Good biocompatibility of the PLGA/β-TCP scaffold was found in the culture and implant tests. Histological samples obtained following implantation of PLGA/β-TCP scaffold loaded with FGF-2 showed significant bone augmentation.

CONCLUSION

The PLGA coating improved the mechanical strength of β-TCP scaffolds while maintaining high porosity and tissue compatibility. PLGA/β-TCP scaffolds, in combination with FGF-2, are bioeffective for bone augmentation.

Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

The KK-Periome database for transcripts of periodontal ligament development

The periodontal ligament (PDL) is a strong connective tissue that surrounds the tooth root, absorbs occlusal forces, and functions as a sense organ. PDL originated from dental follicle (DF), which possessed mesenchymal progenitors in the developing tooth germ. However, as specific marker genes for PDL and DF are currently unavailable, the molecular mechanisms of PDL development are yet to be clarified. To facilitate the identification of such genes, we have previously established a transcriptome database of the human PDL (the KK-Periome database) and screened for specific genes expressed during PDL development. Initial screening of the database revealed two marker genes for distinguishing DF and PDL. The KK-Periome database thus appears to offer a useful resource for investigating genes involved in PDL development.

Establishment of immortalized dental follicle cells for generating periodontal ligament in vivo

The dental follicle is a mesenchymal tissue that surrounds the developing tooth germ. During tooth root formation, periodontal components, viz., cementum, periodontal ligament (PDL), and alveolar bone, are created by dental follicle progenitors. Here, we report the presence of PDL progenitors in mouse dental follicle (MDF) cells. MDF cells were obtained from mouse incisor tooth germs and immortalized by the expression of a mutant human papilloma virus type 16 E6 gene lacking the PDZ-domain-binding motif. MDF cells expressing the mutant E6 gene (MDF( E6-EGFP ) cells) had an extended life span, beyond 150 population doublings (PD). In contrast, normal MDF cells failed to proliferate beyond 10 PD. MDF( E6-EGFP ) cells expressed tendon/ligament phenotype-related genes such as Scleraxis (Scx), growth and differentiation factor-5, EphA4, Six-1, and type I collagen. In addition, the expression of periostin was observed. To elucidate the differentiation capacity of MDF( E6-EGFP ) cells in vivo, the cells were transplanted into severe combined immunodeficiency mice. At 4 weeks, MDF( E6-EGFP ) cell transplants had the capacity to generate a PDL-like tissue that expressed periostin, Scx, and type XII collagen and the fibrillar assembly of type I collagen. Our findings suggest that MDF( E6-EGFP ) cells can act as PDL progenitors, and that these cells may be a useful research tool for studying PDL formation and for developing regeneration therapies.

Catheter dysfunction and thrombosis of double-lumen hemodialysis catheters placed in the femoral vein

OBJECTIVE

Intraluminal thrombosis of the catheter was thought to be a major cause of catheter dysfunction. We evaluated if thrombi appear in the luminal side or outside of the catheters placed in the femoral vein in 21 hemodialysis patients.

METHODS

23 double-lumen catheter (25 cm long and 4 mm diameter polyurethane) strippings were consecutively performed. Mean catheter dwell time was 17.9 +/- 11.2 days (2-45 days). The femoral vein was observed with ultrasound echography, and thrombo-venous ratio (thrombus diameter/vein diameter) was calculated. X-rays were also taken to clearly visualize the thrombi followed by contrast medium injection through the catheter.

RESULTS

Tube-shaped thrombi were echographically detected in 22 of 23 catheters (95.7%) when the catheter was stripped. Ten catheters (43.5%) were stripped due to the reduced blood flow, and tube-shaped thrombi were observed in the femoral vein, whereas no thrombus was found in the intraluminal side of the catheter. In 7 of 23 patients (30.4%) with leg edema on the same side of the catheter, the thrombovenous ratio was 78.9 +/- 7.4%, which was higher than that in the patients without leg edema (52.1 +/- 11.1%).

CONCLUSION

The tube-shaped thrombi, formed around the double-lumen catheter, may cause catheter dysfunction and reduced venous return of the lower legs. The catheter should be removed as soon as thrombosis is diagnosed, especially when accompanied by leg edema.

Mixed lineage kinase LZK forms a functional signaling complex with JIP-1, a scaffold protein of the c-Jun NH(2)-terminal kinase pathway

Leucine zipper-bearing kinase (LZK) is a novel member of the mixed lineage kinase (MLK) protein family, the cDNA of which was first cloned from a human brain cDNA library [Sakuma, H., Ikeda, A., Oka, S., Kozutsumi, Y., Zanetta, J.-P., and Kawasaki, T. (1997) J. Biol. Chem. 272, 28622-28629]. Several MLK family proteins have been proposed to function as MAP kinase kinase kinases in the c-Jun NH(2) terminal kinase (JNK)/stress-activated protein kinase (SAPK) pathway. In the present study, we demonstrated that, like other MLKs, LZK activated the JNK/SAPK pathway but not the ERK pathway. LZK directly phosphorylated and activated MKK7, one of the two MAPKKs in the JNK/SAPK pathway, to a comparable extent to a constitutive active form of MEKK1 (MEKK1DeltaN), suggesting a biological role of LZK as a MAPKKK in the JNK/SAPK pathway. Recent studies have revealed the essential roles of scaffold proteins in intracellular signaling pathways including MAP kinase pathways. JIP-1, one of the scaffold proteins, has been shown to be associated with MLKs, MKK7, and JNK [Whitmarsh, A.J., Cavanagh, J., Tournier, C., Yasuda, J., and Davis, R.J. (1998) Science 281, 1671-1674], suggesting the presence of a selective signaling pathway including LZK, MKK7, and JNK. Consistent with this hypothesis, we provided evidence that LZK is associated with the C-terminal region of JIP-1 through its kinase catalytic domain. In addition, LZK-induced JNK activation was markedly enhanced when LZK and JNK were co-expressed with JIP-1. These results constituted important clues for understanding the molecular mechanisms regulating the signaling specificities of various JNK activators under different cellular conditions.

Evidence for existence of a nuclear pore complex-mediated, cytosol-independent pathway of nuclear translocation of ERK MAP kinase in permeabilized cells

The classical mitogen-activated protein kinase (MAPK, also known as ERK) pathway is widely involved in eukaryotic signal transductions. In response to extracellular stimuli, MAPK becomes activated and translocates from the cytoplasm to the nucleus. At least two pathways for the nuclear import of MAPK are shown to exist; passive diffusion of a monomer and Ran-dependent active transport of a dimer, the detailed molecular mechanism of which is unknown. In this study, we have reconstituted nuclear import of MAPK in vitro by using digitonin-permeabilized cells with GFP-fused MAPK protein (GFP-MAPK), which is too large to pass through the nuclear pore by passive diffusion. GFP-MAPK was able to accumulate in the nucleus irrespective of its phosphorylation state. This import of GFP-MAPK occurred even in the absence of any soluble cytosolic factors or ATP but was inhibited by wheat germ agglutinin or an excess amount of importin-beta or at low temperatures. Moreover, MAPK directly bound to an FG repeat region of nucleoporin CAN/Nup214 in vitro. Taken together, these results suggest the third pathway for nuclear import of MAPK, in which MAPK passes through the nuclear pore by directly interacting with the nuclear pore complex.

Regulation of the activity of the transcription factor Runx2 by two homeobox proteins, Msx2 and Dlx5

BACKGROUND

Runx2, formerly called PEBP2alphaA or Cbfa1, is a transcription factor whose deletion causes a complete lack of ossification. It directly regulates the expression of osteoblast-specific genes through the osteoblast-specific cis-acting element found in the promoter region of these genes.

RESULTS

In this study, we have found conditions in which induction of the expression of Runx2 is not accompanied by expression of an osteoblast-specific gene, osteocalcin in C2C12 cells. This finding suggests the existence of a repressor of the activity of Runx2. We have then found that the homeobox protein Msx2 is able to repress the transcription activity of Runx2 by interacting with it. Furthermore, our results have shown that the other homeobox protein Dlx5 has an activity which interferes with both abilities of Msx2 to interact with Runx2 and repress its transcription activity. It has previously been shown that a missense mutation of Msx2 (P148H) causes Boston-type craniosynostosis in humans. Interestingly, while this mutant form of Msx2 was able to bind to Runx2 and repress its activity, these abilities of Msx2 (P148H) were not subject to regulation by Dlx5.

CONCLUSION

These results suggest that regulation of the activity of Runx2 by Msx2 and Dlx5 plays an important role in the mammalian skull development.

Xenopus FRS2 is involved in early embryogenesis in cooperation with the Src family kinase Laloo

FRS2 has been identified in mammalian cells as a protein that is tyrosine phosphorylated and binds to Grb2 and Shp2 in response to fibroblast growth factor (FGF) or nerve growth factor (NGF) stimulation. But neither its existence in other vertebrate classes or invertebrates nor its function during embryonic development has been defined. Here we have identified and characterized a Xenopus homolog of FRS2 (xFRS2). xFRS2 is tyrosine phosphorylated in early embryos, and overexpression of an unphosphorylatable form of xFRS2 interferes with FGF-dependent mesoderm formation. The Src family kinase Laloo, which was shown to function in FGF signaling during early Xenopus development, binds to xFRS2 and promotes tyrosine phosphorylation of xFRS2. Moreover, xFRS2 and Laloo are shown to bind to Xenopus FGF receptor 1. These results suggest that xFRS2 plays an important role in FGF signaling in cooperation with Laloo during embryonic development.

Results of hyperamplification of centrosomes in naturally developing tumors of dogs

OBJECTIVE

To evaluate results of centrosome hyperamplification in naturally developing tumors of dogs.

SAMPLE POPULATION

Tumor specimens from 9 dogs with tumors (rhabdomyosarcoma, osteosarcoma, chondrosarcoma, myxosarcoma, and mammary gland tumor) and 2 canine osteosarcoma cell lines.

PROCEDURE

3 antibodies for centrosome proteins (ie, anti-gamma-tubulin, anti-BRCA1, and anti-pericentrin) were used for immunohistochemical analysis. Double immunostaining for centrosomes was used to confirm the specificity of these antibodies for centrosomes. Mutational analysis of the canine p53 gene was carried out by polymerase chain reaction-single-strand conformation polymorphism analysis, and expression of canine MDM2 protein was evaluated by use of immunohistochemical analysis, using anti-MDM2 antibody.

RESULTS

Immunohistochemical analysis of dog osteosarcoma cell lines with apparent aneuploidy revealed frequent hyperamplification of centrosomes in the osteosarcoma cell lines. Similar hyperamplified centrosomes were detected in the tumor tissues from all of the 9 tumors. The frequency of cells with hyperamplified centrosomes (3 to 20/cell) in each tumor tissue ranged from 9.50 to 48.1%, whereas centrosome hyperamplification was not observed in normal lymph nodes from these dogs. In 8 of the 9 tumors, mutation of p53 gene or overexpression of MDM2, or both, was detected.

CONCLUSIONS AND CLINICAL RELEVANCE

Various types of naturally developing tumors in dogs often have hyperamplification of centrosomes associated with chromosome instability. Hyperamplification of centrosomes is a novel tumor marker for use in cytologic and histologic examinations of clinical specimens obtained from dogs.

A Novel MAPK Phosphatase MKP-7 Acts Preferentially on JNK/SAPK and p38α and β MAPKs

Mitogen-activated protein kinases (MAPKs) are inactivated via dephosphorylation of either the threonine or tyrosine residue or both in the P-loop catalyzed by protein phosphatases which include serine/threonine phosphatases, tyrosine phosphatases, and dual specificity phosphatases. Nine members of the dual specificity phosphatases specific for MAPKs, termed MKPs, have been reported. Each member has its own substrate specificity, tissue distribution, and subcellular localization. In this study, we have cloned and characterized a novel MKP, designated MKP-7. MKP-7 is most similar to hVH5, a member of previously known MKPs, in the primary structure. MKP-7 is predominantly localized in the cytoplasm when expressed in cultured cells, whereas hVH5 is both in the nucleus and the cytoplasm. MKP-7 binds to and inactivates p38 MAPK and JNK/SAPK, but not ERK. Furthermore, we have found that MKPs have the substrate specificity toward the isoforms of the p38 family (alpha, beta, gamma, and delta). MKP-7 binds to and inactivates p38 alpha and -beta, but not gamma or delta. MKP-5 and CL100/MKP-1 also bind to p38 alpha and -beta, but not gamma or delta. Finally, we propose a tentative classification of MKPs based on the sequence characteristics of their MAPK-docking site.

Specific association of a set of molecular chaperones including HSP90 and Cdc37 with MOK, a member of the mitogen-activated protein kinase superfamily

We have recently identified and cloned a novel member of mitogen-activated protein kinase superfamily protein, MOK (Miyata, Y., Akashi, M., and Nishida, E. (1999) Genes Cells 4, 299-309). To address its regulatory mechanisms, we searched for cellular proteins that specifically associate with MOK by co-immunoprecipitation experiments. Several cellular proteins including a major 90-kDa molecular chaperone HSP90 were found associated with MOK. Treatment of cells with geldanamycin, an HSP90-specific inhibitor, rapidly decreased the protein level of MOK, and the decrease was attributed to enhanced degradation of MOK through proteasome-dependent pathways. Our data suggest that the association with HSP90 may regulate intracellular protein stability and solubility of MOK. Experiments with a series of deletion mutants of MOK indicated that the region encompassing the protein kinase catalytic subdomains I-IV is required for HSP90 binding. Closely related protein kinases (male germ cell-associated kinase and male germ cell-associated kinase-related kinase) were also found to associate with HSP90, whereas conventional mitogen-activated protein kinases (extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase/stress-activated protein kinase) were not associated with HSP90. In addition, we found that other molecular chaperones including Cdc37, HSC70, HSP70, and HSP60 but not GRP94, FKBP52, or Hop were detected specifically in the MOK-HSP90 immunocomplexes. These results taken together suggest a role of a specific set of molecular chaperones in the stability of signal-transducing protein kinases.

Differential control of cellular gene expression by diffusible and non-diffusible EGF

Cell gene expression is affected by both the kind and mode of growth factor stimulation (diffusive vs. non-diffusive). Epidermal growth factor (EGF) was pattern-immobilized on a polystyrene plate. Although the growth of the rat phaeochromocytoma cell line PC12 is stimulated by diffusible EGF, and differentiation is stimulated by diffusible nerve growth factor (NGF), immobilized (non-diffusible) EGF stimulated PC12 differentiation. The immobilized EGF caused a long-lasting stimulation of the intracellular signal protein mitogen-associated protein MAP kinase (MAPK, also known as ERK) and p38 (a subfamily of the MAPK superfamily) in cells, as did diffusible NGF. The switching between growth stimulation and differentiation is considered to be due to the duration of the stimulus. The function of the biosignal conjugate was regulated using conjugation methodology.

ERK induces p35, a neuron-specific activator of Cdk5, through induction of Egr1

The classical mitogen-activated protein kinase (MAPK; also known as extracellular-signal-regulated kinase), ERK cascade has been shown to have a crucial role in cell proliferation and differentiation. In PC12 cells, sustained activation of ERK induced by nerve-growth factor (NGF) is essential for neuronal differentiation. However, downstream targets of ERK that are essential for neuronal differentiation have not been defined. Here we show that NGF induces strong, sustained expression of p35, the neuron-specific activator of cyclin-dependent kinase 5 (Cdk5), through activation of the ERK pathway. The induced kinase activity of Cdk5 is required for NGF-induced neurite outgrowth. Our results indicate that sustained activation of ERK is necessary and sufficient for strong induction of p35. Furthermore, the transcription factor Egr1, is induced by NGF through the ERK pathway and mediates induction of p35 by ERK. Our results thus define an essential signalling pathway, downstream of ERK/MAPK, that leads to neuronal differentiation.

Polo-like kinase 1 phosphorylates cyclin B1 and targets it to the nucleus during prophase

In vertebrate cells, the nuclear entry of Cdc2-cyclin B1 (MPF) during prophase is thought to be essential for the induction and coordination of M-phase events. Phosphorylation of cyclin B1 is central to its nuclear translocation, but the kinases that are responsible remain unknown. Here we have purified a protein kinase from Xenopus M-phase extracts that phosphorylates a crucial serine residue (S147) in the middle of the nuclear export signal sequence of cyclin B1. We have identified this kinase as Plx1 (ref. 16), a Xenopus homologue of Polo-like kinase (Plk)-1. During cell-cycle progression in HeLa cells, a change in the kinase activity of endogenous Plk1 toward S147 and/or S133 correlates with a kinase activity in the cell extracts. An anti-Plk1 antibody depletes the M-phase extracts of the kinase activity toward S147 and/or S133. An anti-phospho-S147 antibody reacts specifically with cyclin B1 only during G2/M phase. A mutant cyclin B1 in which S133 and S147 are replaced by alanines remains in the cytoplasm, whereas wild-type cyclin B1 accumulates in the nucleus during prophase. Co-expression of constitutively active Plk1 stimulates nuclear entry of cyclin B1. Our results indicate that Plk1 may be involved in targeting MPF to the nucleus during prophase.

Coronin forms a stable dimer through its C-terminal coiled coil region: an implicated role in its localization to cell periphery

BACKGROUND

Coronin is an actin-binding protein, which contains WD (Trp-Asp) repeats and a coiled-coil motif, and plays a role in regulating organization of the actin cytoskeletal network. Coronin localizes to the cell periphery, is involved in lamellipodium extension, and has an implicated role in cytokinesis, cell motility and phagocytosis.

RESULTS

Our experiments with two different tagged forms of Xenopus coronin (Xcoronin) have shown that Xcoronin forms an oligomer. This oligomer complex is stable, resistant to 2.4 M NaCl, 0.6 M KI or 2 M urea. Physiochemical analysis of endogenous Xcoronin and the protein expressed in COS7 cells or in bacteria has revealed that the oligomer complex is an Xcoronin dimer. A C-terminal coiled-coil motif of Xcoronin is necessary and sufficient for the dimerization. Mutations in the coiled-coil motif generated dimerization deficient mutants of Xcoronin. Moreover, these mutant forms of Xcoronin failed to localize to the cell periphery, suggesting that dimerization is important for the proper subcellular localization of Xcoronin.

CONCLUSION

Xcoronin forms a stable dimer via its C-terminal coiled-coil region. We propose that coronin dimerization is necessary for its proper subcellular localization and function.

The ERK MAP kinase pathway mediates induction of SGK (serum- and glucocorticoid-inducible kinase) by growth factors

BACKGROUND

The ERK MAP kinase pathway plays a pivotal role in growth factor-induced gene expression. However, genes whose expression is induced by the ERK pathway are not fully defined.

RESULTS

We have identified SGK (serum- and glucocorticoid-inducible kinase) as an ERK-inducible gene by the subtractive screening of Raf-inducible genes. SGK is known to be similar in primary structure to AKT/PKB, PKC and PKA. Treatment of quiescent NIH-3T3 cells with FGF, PDGF or TPA, which induced the sustained activation of ERKs, resulted in the strong induction of SGK, whereas treatment with EGF, which induced the transient activation of ERKs, did not induce a strong expression of SGK. The induction of SGK was blocked by pre-treatment with a specific MEK inhibitor U0126, and expression of constitutively active MEK was able to induce SGK. Treatment with cycloheximide or vanadate prolonged the increased expression of SGK by FGF, concomitant with a more prolonged activation of ERKs.

CONCLUSION

Growth factor-induced activation of the ERK MAP kinase pathway is necessary and sufficient for the induction of SGK.

Identification and characterization of a novel MAP kinase kinase kinase, MLTK

The MAPK cascades regulate a wide variety of cellular functions, including cell proliferation, differentiation, and stress responses. Here we have identified a novel MAP kinase kinase kinase (MAPKKK), termed MLTK (for MLK-like mitogen-activated protein triple kinase), whose expression is increased by activation of the ERK/MAPK pathway. There are two alternatively spliced forms of MLTK, MLTKalpha and MLTKbeta. When overexpressed in cells, both MLTKalpha and MLTKbeta are able to activate the ERK, JNK/SAPK, p38, and ERK5 pathways. Moreover, both MLTKalpha and MLTKbeta are activated in response to osmotic shock with hyperosmolar media through autophosphorylation. Remarkably, expression of MLTKalpha, but not MLTKbeta, in Swiss 3T3 cells results in the disruption of actin stress fibers and dramatic morphological changes. A kinase-dead form of MLTKalpha does not cause these phenomena. Inhibition of the p38 pathway significantly blocks MLTKalpha-induced stress fiber disruption and morphological changes. These results suggest that MLTK is a stress-activated MAPKKK that may be involved in the regulation of actin organization.

Bone resorption and local interleukin-1alpha and interleukin-1beta synthesis induced by Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis lipopolysaccharide

Different types of periodontopathic bacterial lipopolysaccharide (LPS) exert various biological activities in vitro. However, whether or not these activities also occur in vivo remains unclear. Thus the present study investigates bone resorption, as well as local IL-1alpha and IL-1beta synthesis induced by Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis LPS in the periodontal tissue of mice. Both types of LPS were injected into mouse gingiva every 48 h and the animals were sacrificed 6 h after the 1st. 4th, 7th, 10th, 13th, 16th, 20th, or 24th injection. Bone resorption in the injected gingiva was histopathologically and histomorphometrically investigated and local concentrations of IL-1alpha and IL-1beta were detected using an enzyme-linked immunosorbent assay. The active resorption ratio was significantly higher in the group given the 10th injection of LPS from A. actinomycetemcomitans than in the group given P. gingivalis LPS. Furthermore, A. actinomycetemcomitans LPS stimulated significantly more synthesis of IL-1alpha than P. gingivalis LPS after the 4th and 10th injections. and of IL-1beta after the 4th, 7th, 10th, 13th, 16th and 20th injections. These results suggest that A. actinomycetemcomitans LPS is a more potent inducer of bone resorption and synthesis of IL-1alpha and IL-1beta in the short term than P. gingivalis LPS.

Two distinct action mechanisms of immunophilin-ligand complexes for the blockade of T-cell activation

The immunosuppressive effects of cyclosporin A (CsA) and FK506 are mediated through binding to immunophilins. Here we show that FK506-FKBP complex suppresses the activation of JNK and p38 pathways at a level upstream of mitogen-activated protein kinase (MAPK) kinase kinase (MAPKK-K) besides the calcineurin-NFAT pathway. A238L, a viral gene product that binds to immunophilin, also blocks activation of both pathways. In contrast, direct inhibitors of calcineurin, Cabin 1 and FR901725, suppress the activation of NFAT but not the JNK or p38 pathway. We further demonstrate that co-expression of a constitutively active NFAT and a constitutively active MEKK1 renders the interleukin-2 promoter in Jurkat T lymphocytes resistant to CsA and FK506, whereas Jurkat cells expressing a constitutively active NFAT alone are still sensitive to CsA or FK506. Therefore, CsA and FK506 exert their immunosuppressive effects through targeting both the calcineurin-dependent NFAT pathway and calcineurin-independent activation pathway for JNK and p38.

Identification and characterization of Caenorhabditis elegans gamma-tubulin in dividing cells and differentiated tissues

gamma-Tubulin is an essential component of the microtubule-nucleation machinery and therefore plays a crucial role during mitosis. To gain further insights into the function of this protein in the events that take place during embryogenesis and differentiation, we carried out detailed studies on gamma-tubulin during all the developmental stages of Caenorhabditis elegans. We identified the gamma-tubulin gene from this organism and analyzed the localization of the protein by both immunofluorescence and GFP reporter construct. We show that gamma-tubulin association with the centrosome is highly dynamic in mitotic cells, being massively recruited at prophase and released at anatelophase. This accumulation in mitotic centrosomes is dramatic during the first embryonic divisions. We provide the first description of the morphological changes at the centrosome level during the orientation of the mitotic spindle and the flattening of the posterior aster. Loss of function of the gamma-tubulin gene by RNAi induces a strong polyploidization of mitotic germ cells and embryos, but does not affect meiosis and pronuclear migration. In addition, we demonstrate the prominent redistribution of gamma-tubulin in adults at basal bodies of amphid and phasmid neurons, and at the apical membrane of polarized intestinal cells.

Aortic atheromatous lesions developed in APA hamsters with streptozotocin induced diabetes: a new animal model for diabetic atherosclerosis. 1. Histopathological studies

To develop an adequate animal model for atherosclerosis in large vessels of patients with diabetes, i.e. diabetic macroangiopathy, we induced diabetes in APA hamsters with a single injection of streptozotocin (SZ) and examined the aorta histopathologically and immunohistochemically. As a result, hyperglycemia and hyperlipidemia were continuously observed for 26 weeks after the SZ injection (WAI) in APA hamsters. Fatty streaks characterized by a subendothelial accumulation of many foam cells were observed, limited to the aortic arches as early as 6 WAI. In addition to larger fatty streaks developing with the duration of diabetes, fibrous plaques and plaques containing calcium deposits or cholesterol clefts developed at 26 WAI. These lesions are generally similar to the atheromatous lesions developed in humans. Moreover, depositions of apolipoprotein E and advanced glycation end-products immunohistochemically detected in the lesions were very similar to those found in humans. The diabetic APA hamster is therefore considered to be a useful model for studying the formation of atheromatous lesions in diabetic patients.

Regulation of intracellular dynamics of Smad4 by its leucine-rich nuclear export signal

Smad family proteins play a pivotal role in transmitting the transforming growth factor-beta (TGF-beta) superfamily signals from the cell surface to the nucleus. In response to ligand stimulation, Smad4 forms a complex with respective receptor-specific Smads, and the complex translocates into the nucleus and regulates gene expression. Thus, the nuclear entry of the Smad complex is one of the key steps in signal transduction. However, little is known about regulatory mechanisms for nucleocytoplasmic transport of Smads. Here we report identification of a functional, leucine-rich nuclear export signal (NES) in Smad4, which regulates subcellular distribution of Smad4. We then show evidence suggesting that the NES-dependent cytoplasmic localization of Smad4 is important for ensuring optimal TGF-beta responsivenesses in transcriptional activation. Moreover, we show that the NES of Smad4 is specifically inactivated by the stimulus-dependent hetero-oligomerization with receptor-specific Smads during the TGF-beta-induced nuclear translocation of Smad4. Taken together, these results suggest an important regulatory role of the NES of Smad4 in TGF-beta signaling.

The TGF-beta family member derrière is involved in regulation of the establishment of left-right asymmetry

Although a number of genes that are involved in the establishment of left-right asymmetry have been identified, earlier events in the molecular pathway developing left-right asymmetry remain to be elucidated. Here we present evidence suggesting that the transforming growth factor-beta family member derrière is involved in the development of left-right asymmetry in Xenopus embryos. Ectopic expression of derrière on the right side can fully invert cardiac and visceral left-right orientation and nodal expression, and expression of a dominant-negative form of derrière on the left side can partially randomize the left-right orientation and nodal expression. Moreover, while expression of the dominant-negative derrière does not inhibit the activity of Vg1 directly, it can rescue the altered left-right orientation induced by Vg1. Vg1 can induce derrière in animal cap explants. These results suggest that derrière is involved in earlier molecular pathways developing the left-right asymmetry.

Identification of a nuclear export signal in MKK6, an activator of the carp p38 mitogen-activated protein kinases

Carp homologues of p38 mitogen-activated protein kinase (MAPK) and its activator MAPK kinase 6 (MAPKK6, referred to as MKK6) were identified. There exist at least two distinct carp p38s, cp38a and cp38b, both of which consist of 361 amino acids. The transcript of c38a was exclusively expressed in the ovary, whereas that of cp38b was ubiquitously expressed. Western blot analysis with anti-(phosphorylated MAPK) Ig specific to the active p38 or JNK has shown that p38 was activated in response to hypertonic stress (1 M sorbitol) in epithelioma papilosum cyprini carp epithelial cells (EPC) and that the activation of p38 proceeded faster to the maximal level than that of JNK. Carp homologue (cMKK6) of p38 activator MKK6 consists of 404 amino acids. It was expressed ubiquitously but was most abundant in the ovary. An in vitro kinase assay demonstrated that cMKK6 is an upstream activator of cp38 and cp38b in carp because it specifically phosphorylated and activated cp38a and cp38b. Interestingly, we found that cMKK6 has a nuclear export signal (NES) sequence in its N-terminal region although upstream activators of stress-activated MAPKs, p38 and JNK, do not in other animals. The NES sequence facilitated nuclear export of cMKK6 and ovalbumin. Leucine residues in the sequence were crucial for the NES activity, as the activity was lost on replacement of the leucines to alanines. The existence of an NES in cMKK6 implies the requisite of strict regulation of the p38 MAPK pathway in carp. The abundance of these components for the stress-activated pathway in the ovary might be related to ectogenetic early development.

Activation of mitogen-activated protein kinases after transient forebrain ischemia in gerbil hippocampus

We investigated the expression, activation, and distribution of c-Jun N-terminal kinases (JNKs), p38 mitogen-activated protein kinases (p38s) and extracellular signal-regulated kinases (ERKs) using Western blotting and immunohistochemistry in gerbil hippocampus after transient forebrain ischemia to clarify the role of these kinases in delayed neuronal death (DND) in the CA1 subfield. Immunoblot analysis demonstrated that activities of JNK, p38, and ERK in whole hippocampus were increased after 5 min of global ischemia. We used an immunohistochemical study to elucidate the temporal and spatial expression of these kinases after transient global ischemia. The immunohistochemical study showed that active JNK and p38 immunoreactivities were enhanced at 15 min of reperfusion and then gradually reduced and disappeared in the hippocampal CA1 region. On the other hand, in CA3 neurons, active JNK and p38 immunoreactivities were enhanced at 15 min of reperfusion and peaked at 6 hr of reperfusion and then gradually reduced but was continuously detected 72 hr after ischemia. Active ERK immunoreactivity was observed transiently in CA3 fibers and dentate gyrus. Pretreatment with SB203580, a p38 inhibitor, but not with PD98059, an ERK kinase 1/2 inhibitor, reduced ischemic cell death in the CA1 region after transient global ischemia by inhibiting the activity of p38. These findings indicate that the p38 pathway may play an important role in DND during brain ischemia in gerbil. Components of the pathway are important target molecules for clarifying the mechanism of neuronal death.