Crosstalk between NRF2 and HIPK2 shapes cytoprotective responses

Homeodomain interacting protein kinase-2 (HIPK2) is a member of the HIPK family of stress-responsive kinases that modulates cell growth, apoptosis, proliferation and development. HIPK2 has several well-characterised tumour suppressor roles, but recent studies suggest it can also contribute to tumour progression, although the underlying mechanisms are unknown. Herein, we have identified novel crosstalk between HIPK2 and the cytoprotective transcription factor NRF2. We show that HIPK2 is a direct transcriptional target of NRF2, identifying a functional NRF2 binding site in the HIPK2 gene locus and demonstrating for the first time a transcriptional mode of regulation for this kinase. In addition, HIPK2 is required for robust NRF2 responsiveness in cells and in vivo. By using both gain-of-function and loss-of-function approaches, we demonstrate that HIPK2 can elicit a cytoprotective response in cancer cells via NRF2. Our results have uncovered a new downstream effector of HIPK2, NRF2, which is frequently activated in human tumours correlating with chemoresistance and poor prognosis. Furthermore, our results suggest that modulation of either HIPK2 levels or activity could be exploited to impair NRF2-mediated signalling in cancer cells, and thus sensitise them to chemotherapeutic drugs.

A novel de novo point mutation of the OCT-binding site in the IGF2/H19-imprinting control region in a Beckwith-Wiedemann syndrome patient

The IGF2/H19-imprinting control region (ICR1) functions as an insulator to methylation-sensitive binding of CTCF protein, and regulates imprinted expression of IGF2 and H19 in a parental origin-specific manner. ICR1 methylation defects cause abnormal expression of imprinted genes, leading to Beckwith-Wiedemann syndrome (BWS) or Silver-Russell syndrome (SRS). Not only ICR1 microdeletions involving the CTCF-binding site, but also point mutations and a small deletion of the OCT-binding site have been shown to trigger methylation defects in BWS. Here, mutational analysis of ICR1 in 11 BWS and 12 SRS patients with ICR1 methylation defects revealed a novel de novo point mutation of the OCT-binding site on the maternal allele in one BWS patient. In BWS, all reported mutations and the small deletion of the OCT-binding site, including our case, have occurred within repeat A2. These findings indicate that the OCT-binding site is important for maintaining an unmethylated status of maternal ICR1 in early embryogenesis.

Cryopreservation of osteoblasts by use of a programmed freezer with a magnetic field

In order to determine a suitable condition for osteoblasts cryopreservation, murine osteoblasts were freezed by programmed freezer with a magnetic field (CAS freezer). After 7 days cryopreservation at -150°, the number of survival cells immediately after thawing and the growth rate of cultured cells for 48 hours were examined. Gene and protein expression of alkaline phosphatase (ALP), osteopontin (OPN) and bone sialoprotein (BSP) were compared between cryopreserved and non-cryopreserved groups. As a result, a plunging temperature of -30°, a hold-time at -5° for 15 minutes and a 0.1 mT of magnetic field led to the largest survival and growth rate. Moreover, there was no significant difference in ALP, OPN and BSP mRNA and protein expression between cryopreserved and control groups. From these results, it was suggested that the CAS freezer is available for osteoblast cryopreservation and bone tissue banking can be established in the future.

Cryopreservation of periodontal ligament cells with magnetic field for tooth banking

The purpose of this study was to establish a long-term tooth cryopreservation method that can be used for tooth autotransplantation. Human periodontal ligament (PDL) cells were frozen in 10% dimethyl sulfoxide (Me(2)SO) using a programmed freezer with a magnetic field. Cells were cryopreserved for 7 days at -150 degrees C. Immediately after thawing, the number of surviving cells was counted and the cells were cultured; cultured cells were examined after 48 h. Results indicated that a 0.01 mT of a magnetic field, a 15-min hold-time, and a plunging temperature of -30 degrees C led to the greatest survival rate of PDL cells. Based on these findings, whole teeth were cryopreserved under the same conditions for 1 year. The organ culture revealed that the PDL cells of cryopreserved tooth with a magnetic field could proliferate as much as a fresh tooth, although the cells did not appear in the cryopreserved tooth without a magnetic field. Histological examination and the transmission electron microscopic image of cryopreserved tooth with a magnetic field did not show any destruction of cryopreserved cells. In contrast, severe cell damage was seen in cells frozen without a magnetic field. These results indicated that a magnetic field programmed freezer is available for tooth cryopreservation.

Correction of severe open bite using miniscrew anchorage

This report describes the treatment of a case of severe open bite with posterior crossbite. While treating open bite, the outcome may not always be successful with orthodontic therapy alone. In such cases, surgical therapy is often chosen to gain a stable occlusion. Skeletal anchorage systems such as miniscrews are now frequently used for correcting severe malocclusion. In this report, we treated an open bite by intruding the molars with miniscrews placed bilaterally in the interdental space between both the upper and lower posterior teeth. The active treatment period was 36 months and the patient's teeth continued to be stable after a retention period of 36 months.

Identification of loss-of-function mutations of SLC35D1 in patients with Schneckenbecken dysplasia, but not with other severe spondylodysplastic dysplasias group diseases

BACKGROUND

Schneckenbecken dysplasia (SBD) is an autosomal recessive lethal skeletal dysplasia that is classified into the severe spondylodysplastic dysplasias (SSDD) group in the international nosology for skeletal dysplasias. The radiological hallmark of SBD is the snail-like configuration of the hypoplastic iliac bone. SLC35D1 (solute carrier-35D1) is a nucleotide-sugar transporter involved in proteoglycan synthesis. Recently, based on human and mouse genetic studies, we showed that loss-of-function mutations of the SLC35D1 gene (SLC35D1) cause SBD.

OBJECT

To explore further the range of SLC35D1 mutations in SBD and elucidate whether SLC35D1 mutations cause other skeletal dysplasias that belong to the SSDD group.

METHODS AND RESULTS

We searched for SLC35D1 mutations in five families with SBD and 15 patients with other SSDD group diseases, including achodrogenesis type 1A, spondylometaphyseal dysplasia Sedaghatian type and fibrochondrogenesis. We identified four novel mutations, c.319C>T (p.R107X), IVS4+3A>G, a 4959-bp deletion causing the removal of exon 7 (p.R178fsX15), and c.193A>C (p. T65P), in three SBD families. Exon trapping assay showed IVS4+3A>G caused skipping of exon 4 and a frameshift (p.L109fsX18). Yeast complementation assay showed the T65P mutant protein lost the transporter activity of nucleotide sugars. Therefore, all these mutations result in loss of function. No SLC35D1 mutations were identified in all patients with other SSDD group diseases.

CONCLUSION

Our findings suggest that SLC35D1 loss-of-function mutations result consistently in SBD and are exclusive to SBD.

Aberrant quality control in the endoplasmic reticulum impairs the biosynthesis of pulmonary surfactant in mice expressing mutant BiP

Accumulation of misfolded proteins in the endoplasmic reticulum (ER) induces the unfolded protein response (UPR), which alleviates protein overload in the secretory pathway. Although the UPR is activated under diverse pathological conditions, its physiological role during development and in adulthood has not been fully elucidated. Binding immunoglobulin protein (BiP) is an ER chaperone, which is central to ER function. We produced knock-in mice expressing a mutant BiP lacking the retrieval sequence to cause a defect in ER function without completely eliminating BiP. In embryonic fibroblasts, the UPR compensated for mutation of BiP. However, neonates expressing mutant BiP suffered respiratory failure due to impaired secretion of pulmonary surfactant by alveolar type II epithelial cells. Expression of surfactant protein (SP)-C was reduced and the lamellar body was malformed, indicating that BiP plays a critical role in the biosynthesis of pulmonary surfactant. Because pulmonary surfactant requires extensive post-translational processing in the secretory pathway, these findings suggest that in secretory cells, such as alveolar type II cells, the UPR is essential for managing the normal physiological ER protein overload that occurs during development. Moreover, failure of this adaptive mechanism may increase pulmonary susceptibility to environmental insults, such as hypoxia and ischemia, ultimately leading to neonatal respiratory failure.

Study on the usefulness of precise and simple dynamic balance tests for the evaluation of recovery from intravenous sedation with midazolam and propofol

BACKGROUND AND OBJECTIVE

Dynamic balance involving movement of the centre of gravity is important for the evaluation of street fitness after sedation. The purpose of this study was to compare the recovery of dynamic balance after intravenous sedation with propofol or midazolam, and to investigate the usefulness of simple dynamic balance tests in evaluating the recovery.

METHODS

Fourteen young male volunteers underwent intravenous sedation with propofol and midazolam for 1 h each at an interval of more than 1 week. Computerized dynamic posturography using a multi-axial tilting platform, the 10-m maximum-speed walking test and the timed 'up & go' test (subjects stand up from a chair, walk 5 m and back with maximum speed and sit down again) were performed before and after sedation. The increase in each variable of the tests described above represents a reduction of function.

RESULTS

The score of the computerized dynamic posturography was significantly lower in propofol sedation than that in midazolam sedation until 40 min after the end of sedation (P = 0.006). The scores of maximum-speed walking test and timed 'up & go' test were significantly lower in propofol sedation than those in midazolam sedation till 60 min after the end of sedation, respectively (P = 0.035 and 0.042). The timed 'up & go' and maximum-speed walking tests were well and significantly correlated with computerized dynamic posturography in midazolam sedation (timed 'up & go' test vs. computerized dynamic posturography: r = 0.66, P < 0.01; and maximum-speed walking test vs. computerized dynamic posturography: r = 0.53, P < 0.01).

CONCLUSION

The timed 'up & go' and maximum-speed walking tests are useful simple dynamic balance tests well correlated with precise computerized dynamic posturography for the evaluation of the recovery of dynamic balance from midazolam sedation in younger adults.

Insulin resistance and increased pancreatic beta-cell proliferation in mice expressing a mutant insulin receptor (P1195L)

Several mutations of the tyrosine kinase domain of insulin receptor (IR) have been clinically reported to lead insulin resistance and insulin hypersecretion in humans. However, it has not been completely clarified how insulin resistance and pancreatic beta-cell function affect each other under the expression of mutant IR. We investigated the response of pancreatic beta-cells in mice carrying a mutation (P1195L) in the tyrosine kinase domain of IR beta-subunit. Homozygous (Ir(P1195L/P1195L)) mice showed severe ketoacidosis and died within 2 days after birth, and heterozygous (Ir(P1195L/wt)) mice showed normal levels of plasma glucose, but high levels of plasma insulin in the fasted state and after glucose loading, and a reduced response of plasma glucose lowering effect to exogenously administered insulin compared with wild type (Ir(wt/wt)) mice. There were no differences in the insulin receptor substrate (IRS)-2 expression and its phosphorylation levels in the liver between Ir(P1195L/wt) and Ir(wt/wt) mice, both before and after insulin injection. This result may indicate that IRS-2 signaling is not changed in Ir(P1195L/wt) mice. The beta-cell mass increased due to the increased numbers of beta-cells in Ir(P1195L/wt) mice. More proliferative beta-cells were observed in Ir(P1195L/wt) mice, but the number of apoptotic beta-cells was almost the same as that in Ir(wt/wt) mice, even after streptozotocin treatment. These data suggest that, in Ir(P1195L/wt) mice, normal levels of plasma glucose were maintained due to high levels of plasma insulin resulting from increased numbers of beta-cells, which in turn was due to increased beta-cell proliferation rather than decreased beta-cell apoptosis.

Recovery of intentional dynamic balance function after intravenous sedation with midazolam in young and elderly subjects

BACKGROUND AND OBJECTIVE

Computerized dynamic posturography using an intentional postural-sway task can be used to assess body-leaning ability and postural-control ability to prevent falls. Falls are the leading cause of morbidity and mortality for the elderly. The purpose of the present study was to evaluate the recovery of intentional dynamic balance function after intravenous sedation with midazolam in elderly subjects in comparison with that in young subjects.

METHODS

Midazolam was administered in small, divided doses over 4-5 min until the Wilson sedation score reached three in 20 young and 18 elderly male volunteers. The dynamic limits of the stability test, in which subjects leaned their body intentionally as indicated by a cursor moving on a computer screen, was determined before (baseline) and 50, 70, 90, 110, and 130 min after administration of midazolam.

RESULTS

The changes from baseline values of path sway and movement time 50 min after the administration of midazolam in elderly subjects (106.8 +/- 101.0%, 4.6 +/- 3.0 s; mean +/- SD) were significantly greater than those (32.9 +/- 87.2%, 1.9 +/- 2.8 s) in young subjects (P = 0.024, P = 0.008), respectively.

CONCLUSIONS

The elderly show slower recovery of the intentional dynamic balance function than do young adults after intravenous sedation with midazolam.

Reduced inflammatory pain in mice deficient in the differential screening-selected gene aberrative in neuroblastoma

Differential screening-selected gene aberrative in neuroblastoma (Dan) protein is produced in small neurons of dorsal root ganglia. Thermal and mechanical allodynia and Fos expression in the spinal dorsal horn evoked by inflammation and neuropathic pain were investigated using Dan-deficient mice. Mice showed pain reactions induced by the introduction of complete Freund's adjuvant (CFA) into their hind paw (inflammatory pain model) and after sciatic nerve ligation (neuropathic pain model). In the inflammatory pain model, thermal and mechanical pain thresholds in Dan-deficient mice were significantly higher than those of wild-type mice. The number of Fos-immunoreactive cells in the dorsal horn during the inflammatory period was significantly less in Dan-deficient mice. However, in the neuropathic pain model, no differences in thermal hypersensitivity, mechanical allodynia, or the number of Fos-immunoreactive cells in the dorsal horn were observed between the mice. These data suggest that Dan may be a neuromodulator in inflammatory pain.

Expression of the Dan gene during chicken embryonic development

The Dan gene was first identified as the putative rat tumor suppressor gene and encodes a protein structurally related to Cerberus and Gremlin in vertebrates. Xenopus DAN, as with Cerberus and Gremlin, was demonstrated to block bone morphogenetic protein (BMP) signaling by binding BMPs, and to be capable of inducing additional anterior structures by ectopic overexpression in Xenopus embryos. DAN, thus, is suggested to play pivotal roles in early patterning and subsequent organ development, as in the case of other BMP antagonists. In this report, we isolated the chicken counterpart of Dan. Chicken Dan is mainly expressed in the cephalic and somitic mesoderm and several placodes during organ development.

Mouse homologue of coq7/clk-1, longevity gene in Caenorhabditis elegans, is essential for coenzyme Q synthesis, maintenance of mitochondrial integrity, and neurogenesis

coq7/clk-1 was isolated from a long-lived mutant of Caenorhabditis elegans, which showed sluggish behavior and an extended life span. Mouse coq7 is homologous to Saccharomyces cerevisiae coq7/cat5 that is required for biosynthesis of coenzyme Q (CoQ), an essential cofactor in mitochondrial respiration. Here we generated COQ7-deficient mice to investigate the biological role of COQ7 in mammals. COQ7-deficient mouse embryos failed to survive beyond embryonic day 10.5, exhibiting small-sized body and delayed embryogenesis. Morphological studies showed that COQ7-deficient neuroepithelial cells failed to show the radial arrangement in the developing cerebral wall, aborting neurogenesis at E10.5. Electron microscopic analysis further showed the enlarged mitochondria with vesicular cristae and enlarged lysosomes filled with disrupted membranes, which is consistent with mitochondriopathy. Biochemical analysis demonstrated that COQ7-deficient embryos failed to synthesize CoQ(9), but instead yielded demethoxyubiquinone 9 (DMQ(9)). Cultured embryonic cells from COQ7-deficient mice were rescued by adding bovine fetal serum in vitro, but exhibited slowed cell proliferation, which resembled to the phenotype of clk-1 with delayed cell divisions. The result implied the essential role of coq7 in CoQ synthesis, maintenance of mitochondrial integrity, and neurogenesis in mice.

Regulation of Th2 cell differentiation by mel-18, a mammalian polycomb group gene

Polycomb group (PcG) gene products regulate homeobox gene expression in Drosophila and vertebrates and also cell cycle progression of immature lymphocytes. In a gene-disrupted mouse for polycomb group gene mel-18, mature peripheral T cells exhibited normal anti-TCR-induced proliferation; however, the production of Th2 cytokines (IL-4, IL-5, and IL-13) was significantly reduced, whereas production of IFNgamma was modestly enhanced. Th2 cell differentiation was impaired, and the defect was associated with decreased levels in demethylation of the IL-4 gene. Significantly, reduced GATA3 induction was demonstrated. In vivo antigen-induced IgG1 production and Nippostrongylus brasiliensis-induced eosinophilia were significantly affected, reflecting the deficit in Th2 cell differentiation. Thus, the PcG gene products play a critical role in the control of Th2 cell differentiation and Th2-dependent immune responses.

Mice doubly deficient for the Polycomb Group genes Mel18 and Bmi1 reveal synergy and requirement for maintenance but not initiation of Hox gene expression

Polycomb group genes were identified as a conserved group of genes whose products are required in multimeric complexes to maintain spatially restricted expression of Hox cluster genes. Unlike in Drosophila, in mammals Polycomb group (PcG) genes are represented as highly related gene pairs, indicative of duplication during metazoan evolution. Mel18 and Bmi1 are mammalian homologs of Drosophila Posterior sex combs. Mice deficient for Mel18 or Bmi1 exhibit similar posterior transformations of the axial skeleton and display severe immune deficiency, suggesting that their gene products act on overlapping pathways/target genes. However unique phenotypes upon loss of either Mel18 or Bmi1 are also observed. We show using embryos doubly deficient for Mel18 and Bmi1 that Mel18 and Bmi1 act in synergy and in a dose-dependent and cell type-specific manner to repress Hox cluster genes and mediate cell survival of embryos during development. In addition, we demonstrate that Mel18 and Bmi1, although essential for maintenance of the appropriate expression domains of Hox cluster genes, are not required for the initial establishment of Hox gene expression. Furthermore, we show an unexpected requirement for Mel18 and Bmi1 gene products to maintain stable expression of Hox cluster genes in regions caudal to the prospective anterior expression boundaries during subsequent development.

Inductive signals from the somatopleure mediated by bone morphogenetic proteins are essential for the formation of the sternal component of avian ribs

The posterior five pairs of avian ribs are composed of vertebral and sternal components, both derived from the somitic mesoderm. For the patterning of the rib cartilage, inductive signals from neighboring tissues on the somitic mesoderm have been suggested to play critical roles. The notochord and surface ectoderm overlying the somitic mesoderm are essentially required for the development of proximal and distal regions of the ribs, respectively. Involvement of the somatopleure in rib development has already been suggested but is less understood than those of the notochord and surface ectoderm. In this study, we reinvestigated the role of the somatopleure during rib development. We first identified the chicken homologue of the mouse Mesenchymal forkhead-1 (cMfh-1) gene based on sequence similarities. cMfh-1 was observed to be expressed in the nonaxial mesoderm, including the somitic mesoderm, and, subsequently, in cartilage forming the ribs, vertebrae, and appendicular skeletal system. In the interlimb region, corresponding to somites 21-25 (or 26), cMfh-1-positive somitic mesoderm was seen penetrating the somatopleure of E4 embryos, and cMfh-1 was used as a molecular marker demarcating prospective rib cartilage. A series of experiments affecting the penetration of the somitic mesoderm into the somatopleure was performed in the present study, resulting in defects in sternal rib formation. The inductive signals emanating from the somatopleure mediated by BMP family proteins were observed to be essentially involved in the ingrowth of the somitic mesoderm. BMP4 alone, however, could not completely replace inductive signals from the somatopleure, suggesting the involvement of additional signals for rib formation.

The role of presenilin 1 during somite segmentation

The Notch signalling pathway plays essential roles during the specification of the rostral and caudal somite halves and subsequent segmentation of the paraxial mesoderm. We have re-investigated the role of presenilin 1 (Ps1; encoded by Psen1) during segmentation using newly generated alleles of the Psen1 mutation. In Psen1-deficient mice, proteolytic activation of Notch1 was significantly affected and the expression of several genes involved in the Notch signalling pathway was altered, including Δ-like3, Hes5, lunatic fringe (Lfng) and Mesp2. Thus, Ps1-dependent activation of the Notch pathway is essential for caudal half somite development. We observed defects in Notch signalling in both the caudal and rostral region of the presomitic mesoderm. In the caudal presomitic mesoderm, Ps1 was involved in maintaining the amplitude of cyclic activation of the Notch pathway, as represented by significant reduction of Lfng expression in Psen1-deficient mice. In the rostral presomitic mesoderm, rapid downregulation of the Mesp2 expression in the presumptive caudal half somite depends on Ps1 and is a prerequisite for caudal somite half specification. Chimaera analysis between Psen1-deficient and wild-type cells revealed that condensation of the wild-type cells in the caudal half somite was concordant with the formation of segment boundaries, while mutant and wild-type cells intermingled in the presomitic mesoderm. This implies that periodic activation of the Notch pathway in the presomitic mesoderm is still latent to segregate the presumptive rostral and caudal somite. A transient episode of Mesp2 expression might be needed for Notch activation by Ps1 to confer rostral or caudal properties. In summary, we propose that Ps1 is involved in the functional manifestation of the segmentation clock in the presomitic mesoderm.

Fulminant Mycoplasma pneumoniae pneumonia

A 64-year-old woman, who was previously in good health was admitted because of progressive respiratory distress. Her chest radiograph revealed bilateral widespread alveolar infiltrates. She was given a diagnosis of pneumonia caused by Mycoplasma pneumoniae serologically, acute respiratory distress syndrome, and disseminated intravascular coagulation. She died of multiple organ failure despite intensive therapy with mechanical ventilation, intravenous erythromycin and corticosteroids, continuous hemodiafiltration, and plasma exchange. Although Mycoplasma pneumoniae infection is usually a benign self-limited disease, this case emphasizes its potentially serious nature even in normal healthy individuals.

Molecular cloning, genetic mapping, and expression of the mouse Sf3b1 (SAP155) gene for the U2 snRNP component of spliceosome

SAP155, a subunit of the U2 snRNP, is essential for prespliceosome assembly and splicing catalysis of the major spliceosome. Moreover, the protein has been identified in the minor (U12-dependent) spliceosome. These facts strongly suggest that SAP155 is shared by two distinct complexes owing to its importance in the removal of any type of intron. Here we have isolated a cDNA encoding the 146-kDa mouse homolog, designated Sf3b1. The amino acid sequence of Sf3b1 is very highly conserved among homologs from Schizosaccharomyces pombe (52.4% identity) to human (99.6%), and the C-terminal 825 residues of these Sf3b1 homologs show even higher identities. This C-terminal region shows significant similarity to the PR65 subunit of protein phosphatase 2A, which is composed of 15 tandem repeats of a 39 amino acid sequence. Mouse genome analyses showed Sf3bh1 to be a single-copy gene mapping to the central part of Chromosome (Chr) 1. Northern blot analysis and whole mount in situ hybridization revealed Sf3b1 to be ubiquitously expressed in a variety of adult tissues and mid-gestation embryos.

Mesenchymal transcription factor Fkh6 is essential for the development and differentiation of parietal cells

The role of transcription factor forkhead homologue 6 (Fkh6) gene expressed only in gastrointestinal mesenchymes on the differentiation of gastric epithelia was analyzed by inactivating the gene by targeting disruption. Gastric mucosa exhibited hyperplasias with disordered glandular structures in the absence of gene. Measurement of acid secretion in the isolated whole stomach demonstrated that both basal and stimulated secretions were severely suppressed in the Fkh6-/- stomach, while immunohistochemical studies showed that comparable numbers of parietal cells were differentiated in both wild-type and Fkh6-/- stomachs. Ultrastructurally Fkh6-/- parietal cells were furnished with developed intracellular canaliculi and many mitochondria, but their canaluculi were not enlarged nor fully connected to the luminal surface even when animals were treated with histamine, suggesting that Fkh6-/- parietal cells were far less responsive to acid secretion-inducing stimulations. Some parietal cells contained secretory granules positively stained with anti-pepsinogen antibodies, indicating that they retained characteristics of oxynticopeptic cells found in lower vertebrates. We thus concluded that Fkh6 plays essential roles for the development and differentiation of parietal cells via epithelial-mesenchymal interactions.

Production of monoclonal antibodies against mammalian Ring1B proteins

The Polycomb group (PcG) genes play a role of transcriptional repressor for long-term maintenance of the Hox cluster gene expression. Recently two structurally similar gene products, Ring1A and Ring1B, were identified. Genetic evidence has indicated that Ring1A has Pc-G properties, however, Ring1B functions are still unknown. To gain functional insights for Ring1B, we raised the mouse monoclonal antibodies (MAbs) against murine Ring1B protein. Using these antibodies, we have detected specifically mouse, human and monkey Ring1B gene products from whole cell extracts in immunoblot and immunoprecipitation analyses. Immunofluorescent staining by the antibodies has shown that endogenous Ring1B proteins clearly co-localize with Ring1A at the pattern of diffuse nuclear speckles. Together with their sequence similarity, Ring1B also may function as a Pc-G protein. Finally, we have proposed that the anti-Ring1B would be useful for biochemical and cytological analyses of Ring1B and Pc-G complex.

Mesp2 initiates somite segmentation through the Notch signalling pathway

The Notch-signalling pathway is important in establishing metameric pattern during somitogenesis. In mice, the lack of either of two molecules involved in the Notch-signalling pathway, Mesp2 or presenilin-1 (Ps1), results in contrasting phenotypes: caudalized versus rostralized vertebra. Here we adopt a genetic approach to analyse the molecular mechanism underlying the establishment of rostro-caudal polarity in somites. By focusing on the fact that expression of a Notch ligand, Dll1, is important for prefiguring somite identity, we found that Mesp2 initiates establishment of rostro-caudal polarity by controlling two Notch-signalling pathways. Initially, Mesp2 activates a Ps1-independent Notch-signalling cascade to suppress Dll1 expression and specify the rostral half of the somite. Ps1-mediated Notch-signalling is required to induce Dll1 expression in the caudal half of the somite. Therefore, Mesp2- and Ps1-dependent activation of Notch-signalling pathways might differentially regulate Dll1 expression, resulting in the establishment of the rostro-caudal polarity of somites.

Deficiency of the macrophage migration inhibitory factor gene has no significant effect on endotoxaemia

By targeted disruption of the MIF gene, we have established a mouse strain deficient in macrophage (Mphi) migration inhibitory factor (MIF). Despite previous reports indicating an essential role of MIF in endotoxaemia, an injection of lipopolysaccharide (LPS) into the MIF-deficient mice (maintained under specific pathogen-free conditions) caused shock. No significant difference was detected between the MIF-deficient mutant and normal mice in susceptibility to LPS for endotoxaemia or tumour necrosis factor-alpha (TNF-alpha) formation upon LPS injection. Peritoneal Mphi from the two strains produced TNF-alpha in response to LPS with similar dose responses. Dexamethasone suppressed the LPS-induced TNF-alpha response of Mphi, but no difference was detected between the Mphi from the two strains. These results suggest that endogenous MIF has no significant effect on the LPS-induced TNF-alpha production and no effect on suppression of the response by glucocorticoids. Thus, MIF is not crucial for LPS-induced immune responses leading to shock.

Involvement of decidual Valpha14 NKT cells in abortion

The immunological mechanisms that regulate abortion are largely unknown. Here, we found that a distinct subset of lymphocytes, Valpha14 NKT cells expressing an invariant antigen receptor encoded by Valpha14/Jalpha281 and Vbeta7 segments, accumulated in the decidua during pregnancy and provoked abortion upon stimulation with alpha-galactosylceramide (alpha-GalCer), a specific ligand for Valpha14 NKT cells. The alpha-GalCer-mediated abortion was not observed in Valpha14 NKT-, IFN-gamma-, tumor necrosis factor alpha-, or perforin-knock-out mice and appeared to be due to the degeneration of embryonic trophoblasts mediated by the activated Valpha14 NKT cells whose perforin-dependent killing and production of IFN-gamma and tumor necrosis factor alpha were essential. The possible role of the decidual Valpha14 NKT cells in the pathogenesis of abortion is discussed.

Zic1 regulates the patterning of vertebral arches in cooperation with Gli3

Skeletal abnormalities are described that appeared in Zic1-deficient mice. These mice show multiple abnormalities in the axial skeleton. The deformities are severe in the dorsal parts of the vertebrae, vertebral arches, but less so in the vertebral bodies (spina bifida occulta). The proximal ribs are deformed having ectopic processes. The abnormalities found in the vertebral arches can be traced back to disturbed segmental patterns of dorsal sclerotome. The Zic1/Gli3 double mutants showed severe abnormalities of vertebral arches not found in single mutants. The abnormalities in the vertebral arches were less severe in Zic1/Pax1 mutants than Zic1/Gli3 mutants, but significantly more pronounced than in Zic1 single mutants. The three genes may act synergistically in the development of the vertebral arches.

Targeted disruption of Traf5 gene causes defects in CD40- and CD27-mediated lymphocyte activation

TRAF5 [tumor necrosis factor (TNF) receptor-associated factor 5] is implicated in NF-kappaB and c-Jun NH(2)-terminal kinase/stress-activated protein kinase activation by members of the TNF receptor superfamily, including CD27, CD30, CD40, and lymphotoxin-beta receptor. To investigate the functional role of TRAF5 in vivo, we generated TRAF5-deficient mice by gene targeting. Activation of either NF-kappaB or c-Jun NH(2)-terminal kinase/stress-activated protein kinase by tumor necrosis factor, CD27, and CD40 was not abrogated in traf5(-/-) mice. However, traf5(-/-) B cells showed defects in proliferation and up-regulation of various surface molecules, including CD23, CD54, CD80, CD86, and Fas in response to CD40 stimulation. Moreover, in vitro Ig production of traf5(-/-) B cells stimulated with anti-CD40 plus IL-4 was reduced substantially. CD27-mediated costimulatory signal also was impaired in traf5(-/-) T cells. Collectively, these results demonstrate that TRAF5 is involved in CD40- and CD27-mediated signaling.

Notochord-dependent expression of MFH1 and PAX1 cooperates to maintain the proliferation of sclerotome cells during the vertebral column development

During axial skeleton development, the notochord is essential for the induction of the sclerotome and for the subsequent differentiation of cartilage forming the vertebral bodies and intervertebral discs. These functions are mainly mediated by the diffusible signaling molecule Sonic hedgehog. The products of the paired-box-containing Pax1 and the mesenchyme forkhead-1 (Mfh1) genes are expressed in the developing sclerotome and are essential for the normal development of the vertebral column. Here, we demonstrate that Mfh1 like Pax1 expression is dependent on Sonic hedgehog signals from the notochord, and Mfh1 and Pax1 act synergistically to generate the vertebral column. In Mfh1/Pax1 double mutants, dorsomedial structures of the vertebrae are missing, resulting in extreme spina bifida accompanied by subcutaneous myelomeningocoele, and the vertebral bodies and intervertebral discs are missing. The morphological defects in Mfh1/Pax1 double mutants strongly correlate with the reduction of the mitotic rate of sclerotome cells. Thus, both the Mfh1 and the Pax1 gene products cooperate to mediate Sonic hedgehog-dependent proliferation of sclerotome cells.

The role of Bcl6 in mature cardiac myocytes

OBJECTIVE

The Bcl6 gene encodes a sequence-specific transcriptional repressor and is ubiquitously expressed in adult murine tissues including heart muscle. The objective of this study was to examine the role of Bcl6 in cardiac myocytes.

METHOD

We developed Bcl6-deficient (Bcl6-/-) mice and histologically examined hearts from these mice.

RESULTS

Massive myocarditis with eosinophilic infiltration occurred in Bcl6-/- mice after 4-6 weeks of age. Since expression of the Bcl6 gene was induced in normal cardiac myocytes after 2 weeks of age and thereafter detected through adulthood, loss of Bcl6 in mature cardiac myocytes may be related to the induction of eosinophilic myocarditis. To examine the effects of eosinophils from Bcl6-/- mice on normal hearts, bone marrow cells from Bcl6-/- mice were adoptively transferred into sublethally irradiated RAG1-deficient mice. Although massive eosinophilic infiltration was detected in conjunctivas and spleens from the chimeric mice, myocarditis was never observed. Electron microscopic analysis of cardiac myocytes from Bcl6-/- mice revealed a spectrum of degenerative changes prior to eosinophilic infiltration.

CONCLUSION

Bcl6 maynot be essential for the maturation of cardiac myocytes but may play a role in protecting mature cardiac myocytes from eosinophilic inflammation.

Bilateral pleuritis caused by Legionella micdadei

A 58-year-old woman was hospitalized because of progressive respiratory distress. She had a history of myasthenia gravis and invasive thymoma. After thymectomy, she had been administered oral prednisolone and intrathoracic anti-cancer drugs postoperatively. Her chest radiograph revealed bilateral pleural effusions. Legionella micdadei (L. micdadei) was isolated from the pleural effusions, and she was diagnosed as pleuritis caused by L. micdadei. She died despite intensive therapy with mechanical ventilation, drainage tube in the chest and intravenous erythromycin. Although only two cases of Legionellosis caused by L. micdadei have been reported in Japan, clinicians should be aware of L. micdadei as one of the candidates for infection in immunosuppressed hosts.

Fc receptor beta subunit is required for full activation of mast cells through Fc receptor engagement

The high-affinity IgE receptor (Fc epsilonRI) and the low-affinity IgG receptor (Fc gammaRIII) on mast cells are the key molecules involved in triggering the allergic reaction. These receptors share the common beta subunit (FcRbeta) which contains an immunoreceptor tyrosine-based activation motif and transduces the signals of these receptors' aggregation. In rodents, FcRbeta is essential for the cell surface expression of the Fc epsilonRI. In humans, the FcRbeta gene was reported to be one of the candidate genes causing atopic diseases. However, the role of FcRbeta in vivo still remains ambiguous. To elucidate the functions of FcRbeta, we developed the mice lacking FcRbeta [FcRbeta(-/-)]. The FcRbeta(-/-) mice lacked the expression of the Fc epsilonRI on mast cells and IgE-mediated passive cutaneous anaphylaxis (PCA) was not induced in FcRbeta(-/-) mice as was expected. In these mice, the expression of IgG receptors on mast cells was augmented but the IgG-mediated PCA reaction was attenuated. Although with bone marrow-derived cultured mast cells from FcRbeta(-/-), adhesion to fibronectin and Ca2+ flux upon aggregation of IgG receptors were enhanced, mast cells co-cultured with 3T3 fibroblasts exhibited impaired degranulation on receptor aggregation. These observations indicate that FcRbeta accelerates the degranulation of mature mast cells via the IgG receptor in connective tissues.

Natural killer-like nonspecific tumor cell lysis mediated by specific ligand-activated Valpha14 NKT cells

We have recently identified alpha-galactosylceramide (alpha-GalCer) as a specific ligand for an invariant Valpha14/Vbeta8.2 T cell receptor exclusively expressed on the majority of Valpha14 NKT cells, a novel subset of lymphocytes. Here, we report that alpha-GalCer selectively activates Valpha14 NKT cells resulting in prevention of tumor metastasis. The effector mechanisms of the ligand-activated Valpha14 NKT cells seem to be mediated by natural killer (NK)-like nonspecific cytotoxicity. Indeed, the cytotoxic index obtained by alpha-GalCer-activated Valpha14 NKT cells was reduced by the addition of cold target tumor cells or by treatment with concanamycin A, which inhibits activation and secretion of perforin, but not by mAbs against molecules involved in the NKT cell recognition and conventional cytotoxicity, such as CD1d, Vbeta8, NK1. 1, Ly49C, Fas, or Fas ligand. These results suggest that the ligand-activated Valpha14 NKT cells kill tumor cells directly through a CD1d/Valpha14 T cell receptor-independent, NK-like mechanism.

CD1d-restricted and TCR-mediated activation of valpha14 NKT cells by glycosylceramides

Natural killer T (NKT) lymphocytes express an invariant T cell antigen receptor (TCR) encoded by the Valpha14 and Jalpha281 gene segments. A glycosylceramide-containing alpha-anomeric sugar with a longer fatty acyl chain (C26) and sphingosine base (C18) was identified as a ligand for this TCR. Glycosylceramide-mediated proliferative responses of Valpha14 NKT cells were abrogated by treatment with chloroquine-concanamycin A or by monoclonal antibodies against CD1d/Vbeta8, CD40/CD40L, or B7/CTLA-4/CD28, but not by interference with the function of a transporter-associated protein. Thus, this lymphocyte shares distinct recognition systems with either T or NK cells.

Requirement for Valpha14 NKT cells in IL-12-mediated rejection of tumors

A lymphocyte subpopulation, the Valpha14 natural killer T (NKT) cells, expresses both NK1.1 and a single invariant T cell receptor encoded by the Valpha14 and Jalpha281 gene segments. Mice with a deletion of the Jalpha281 gene segment were found to exclusively lack this subpopulation. The Valpha14 NKT cell-deficient mice could no longer mediate the interleukin-12 (IL-12)-induced rejection of tumors. Although the antitumor effect of IL-12 was thought to be mediated through natural killer cells and T cells, Valpha14 NKT cells were found to be an essential target of IL-12, and they mediated their cytotoxicity by an NK-like effector mechanism after activation with IL-12.

Essential roles of the winged helix transcription factor MFH-1 in aortic arch patterning and skeletogenesis

Mesenchyme Fork Head-1 (MFH-1) is a forkhead (also called winged helix) transcription factor defined by a common 100-amino acid DNA-binding domain. MFH-1 is expressed in non-notochordal mesoderm in the prospective trunk region and in cephalic neural-crest and cephalic mesoderm-derived mesenchymal cells in the prechordal region of early embryos. Subsequently, strong expression is localized in developing cartilaginous tissues, kidney and dorsal aortas. To investigate the developmental roles of MFH-1 during embryogenesis, mice lacking the MFH-1 locus were generated by targeted mutagenesis. MFH-1-deficient mice died embryonically and perinatally, and exhibited interrupted aortic arch and skeletal defects in the neurocranium and the vertebral column. Interruption of the aortic arch seen in the mutant mice was the same as in human congenital anomalies. These results suggest that MFH-1 has indispensable roles during the extensive remodeling of the aortic arch in neural-crest-derived cells and in skeletogenesis in cells derived from the neural crest and the mesoderm.

Heat shock-induced homeotic transformations of the axial skeleton and associated shifts of Hox gene expression domains in mouse embryos

Pregnant ICR mice were immersed in water at 42 degrees C for up to 15 min on Day 8.5 of gestation (plug day = Day 0), and their term fetuses were double stained with alcian blue and alizarin red S for skeletal examination. Heat exposure for 15 min induced homeotic vertebral transformations in more than one-third of the living fetuses, in which the morphologic identity of vertebrae (T6-S1) was shifted anteriorly by one or two segmental levels. The frequency of fetuses with vertebral transformations and the degree of the shift of vertebral identity were dependent on the length of heat exposure. The expression domains of Hoxa-7, Hoxc-8, and Hoxc-9 genes as examined by whole mount in situ hybridization were found to be shifted anteriorly in heated embryos. The heat-induced shifts of Hox gene expression domains were consistent with the observed vertebral transformations and suggested correlation or colinearity with the clustered organization of the Hox genes. The result of the present study indicates that a brief heat shock at a critical stage of differentiation can interfere with the normal establishment of Hox codes and subsequently, perturb the specification of vertebral identity.

Pax genes and organogenesis

Pax genes are a family of developmental control genes that encode nuclear transcription factors. They are characterized by the presence of the paired domain, a conserved amino acid motif with DNA-binding activity. Originally, paired-box-containing genes were detected in Drosophila melanogaster, where they exert multiple functions during embryogenesis. In vertebrates, Pax genes are also involved in embryogenesis. Mutations in four out of nine characterized Pax genes have been associated with either congenital human diseases such as Waardenburg syndrome (PAX3), Aniridia (PAX6), Peter's anomaly (PAX6), renal coloboma syndrome (PAX2) or spontaneous mouse mutants (undulated (Pax1), Splotch (Pax3), Small eye (Pax6), Pax2(1)Neu), which all show defects in development. Recently, analysis of spontaneous and transgenic mouse mutants has revealed that vertebrate pax genes are key regulators during organogenesis of kidney, eye, ear, nose, limb muscles, vertebral column and brain. Like their Drosophila counterparts, vertebrate Pax genes are involved in pattern formation during embryogenesis, possibly by determining the time and place of organ initiation or morphogenesis. For most tissues, however, the nature of the primary developmental action of Pax transcription factors remains to be elucidated. One predominant theme is signal transduction during tissue interactions, which may lead to a position-specific regulation of cell proliferation.

A novel pathogenesis of megacolon in Ncx/Hox11L.1 deficient mice

The Ncx/Hox11L.1 gene, a member of the Hox11 homeobox gene family, is mainly expressed in neural crest-derived tissues. To elucidate the role of Ncx/Hox11L.1, the gene has been inactivated in embryonic stem cells by homologous recombination. The homozygous mutant mice were viable. These mice developed megacolon with enteric ganglia by age 3-5 wk. Histochemical analysis of the ganglia revealed that the enteric neurons hyperinnervated in the narrow segment of megacolon. Some of these neuronal cells degenerated and neuronal cell death occurred in later stages. We propose that Ncx/Hox11L.1 is required for maintenance of proper functions of the enteric nervous system. These mutant mice can be used to elucidate a novel pathogenesis for human neuronal intestinal dysplasia.

Disruption of the Bcl6 gene results in an impaired germinal center formation

The Bcl6 gene has been identified from the chromosomal translocation breakpoint in B cell lymphomas, and its products are expressed highly in germinal center (GC) B cells. To investigate the function of Bcl6 in lymphocytes, we have generated RAG1-deficient mice reconstituted with bone marrow cells from Bcl6-deficient mice (Bcl6(-/-)RM). Lymphogenesis in primary lymphoid tissues of Bcl6(-/-)RM is normal, and Bcl6(-/-)RM produced control levels of primary IgG1 antibodies specific to T cell-dependent antigens. However, GCs were not found in these mice. This defect was mainly due to the abnormalities of B cells. Therefore, Bcl6 is essential for the differentiation of GC B cells.

Mesp2: a novel mouse gene expressed in the presegmented mesoderm and essential for segmentation initiation

We isolated a novel bHLH protein gene Mesp2 (for mesoderm posterior 2) that cross-hybridizes with Mesp1 expressed in the early mouse mesoderm. Mesp2 is expressed in the rostral presomitic mesoderm, but down-regulated immediately after the formation of the segmented somites. To determine the function of MesP2 protein (MesP2) in somitogenesis, we generated Mesp2-deficient mice by gene targeting. The homozygous Mesp2 (-/-) mice died shortly after birth and had fused vertebral columns and dorsal root ganglia, with impaired sclerotomal polarity. The earliest defect in the homozygous embryos was a lack of segmented somites. Their disruption of the metameric features, altered expression of Mox-1, Pax-1, and Dll1, and lack of expression of Notch1, Notch2, and FGFR1 suggested that MesP2 controls sclerotomal polarity by regulating the signaling systems mediated by notch-delta and FGF, which are essential for segmentation.