Biomedical subjects

N Arai

Publications and source records attributed to N Arai.

At least 19 recordsLinked to original sources

PubMed1999

Two independent calcineurin-binding regions in the N-terminal domain of murine NF-ATx1 recruit calcineurin to murine NF-ATx1.

Intracellular calcium regulates events controlling nuclear translocation of nuclear factor of activated T cells (NF-AT). Calcium-dependent phosphatase calcineurin (CN) plays a central role in this process. Structural and functional analyses of the N-terminal domain of murine NF-ATx1, a member of the NF-AT family, have defined two distinct CN binding regions (CNBRs), CNBR1 and CNBR2, which are located in the region preceding the SP boxes of serine/proline-rich sequences and the region between the SP boxes and Rel similarity domain, respectively. The binding of murine NF-ATx1 (mNF-ATx1) to CN was abolished by deletion of these two regions, yet was unaffected by the individual deletion. In contrast, the nuclear translocation of mNF-ATx1 was much reduced when only CNBR2 was removed. Luciferase assay revealed that both regions are required for mNF-ATx1-dependent activation of the murine IL-2 promoter. Most importantly, recombinant CNBR2 bound CN with a higher affinity, and when expressed in Jurkat cells, it functioned as a dominant negative mutant that prevented the transcription driven by exogenous mNF-ATx1, probably by interfering with the function of CN. We propose that activation of mNF-ATx1 can be modulated through two distinct CN target regions. Our findings provide a new opportunity for pharmacological intervention with Ca2+-dependent signaling events.

Animals↗

PubMed1999

Can secondary degeneration accelerate the formation of neurofibrillary tangles? A case of hemispheric infarction showing asymmetric degeneration of the substantia nigra, red nuclei, inferior olivary nuclei and dentate nuclei with concomitant changes of progressive supranuclear palsy.

A case of hemispheric infarction involving the territory of the right middle cerebral artery and the thalamus showed conspicuous asymmetric degeneration in the substantia nigra, red nuclei, inferior olivary nuclei and dentate nuclei with concomitant changes of progressive supranuclear palsy (PSP). The right substantia nigra and red nucleus showed loss of neurons and proliferation of astrocytes. The right olivary nucleus was hypertrophic, while the neuronal loss and astrocytosis in the dentate nucleus were predominant on the contralateral side. Modified Gallyas-Braak staining revealed the extensive distribution of neurofibrillary tangles (NFTs), threads and intraglial argyrophilic structures in the globus pallidus, subthalamic nuclei, cerebral cortex and dentate nuclei, as well as in the affected brain stem nuclei, with a distinct predominance on the affected side. In this case, the one-sided predominance of the extended degeneration in these brain stem and cerebellar areas is considered, in addition to the PSP changes, to be due to secondary retrograde degeneration via the nigrostriatal and dentato-rubro-thalamic pathways following the hemispheric infarction, and to also be the result of disruption of the dentato-olivary fiber connections. In addition, because of the predominant distribution of NFTs on the more degenerated side, it is surmised that the formation of NFTs may be accelerated by secondary degeneration.

Aged↗

PubMed1999

Surgical treatment of a case of early infantile epileptic encephalopathy with suppression-bursts associated with focal cortical dysplasia.

We report a surgically treated case of early infantile epileptic encephalopathy (EIEE) with suppression-bursts associated with focal cortical dysplasia. Tonic-clonic seizures followed by a series of spasms occurred about a hundred times a day at a few days of age. Interictal electroencephalogram (EEG) revealed a suppression-burst pattern that was predominant in the left hemisphere. Magnetic resonance imaging (MRI) suggested focal cortical dysplasia in the left prefrontal area. Combination therapies with antiepileptic treatments showed only partial efficacy. The patient underwent lesionectomy at age 4 months, after which he gradually showed psychomotor development and a decrease of spasms to 0-2 series daily. In cases of EIEE with focal cortical dysplasia, surgical treatment may have beneficial effects on both psychomotor development and seizure control.

Adrenocorticotropic Hormone↗

PubMed1999

An aggressive desmoid tumor in a patient with familial adenomatous polyposis: immunohistochemical findings.

A case of an aggressive desmoid tumor in a patient with familial adenomatous polyposis is described. The lesion rapidlyenlarged with compression of adjacent structures including the ureter and small bowel, and the patient died because of small bowel perforation and hydronephrosis 3 years after detection of small desmoid tumors at the time of a prophylactic coloproctectomy for a colon carcinoma. Immunohistochemically, proliferating cell nuclear antigen (PCNA), p21WAF1/CIP1 and cathepsin D indices, but not the bcl-2 index, which were defined as the numbers of immunoreactive tumor cells per 1000 tumor cells, increased in line with tumor progression. The tumor did not show staining for collagen IV, but was characterized by intense staining for basic fibroblast growth factor (bFGF). Accordingly, tumor aggression was related to increases in both cell proliferation and protease activity, as well as an enhanced expression of bFGF. In addition, the desmoid tumor showed deregulation between PCNA and p21WAF1/CIP1 because the normal inverse relation between these two was not apparent.

Adenomatous Polyposis Coli↗

PubMed1998

Carboxyl-terminal 15-amino acid sequence of NFATx1 is possibly created by tissue-specific splicing and is essential for transactivation activity in T cells.

NFAT regulates transcription of a number of cytokine and other immunoregulatory genes. We have isolated NFATx, which is one of four members of the NFAT family of transcription factors and is preferentially expressed in the thymus and peripheral blood leukocytes, and an isoform of NFATx, NFATx1. Here we provide evidence showing that 15 amino acids in the carboxyl-terminal end of NFATx1 are required for its maximum transactivation activity in Jurkat T cells. A fusion between these 15 amino acids and the GAL4 DNA binding domain was capable of transactivating reporters driven by the GAL4 DNA binding site. Interestingly, this 15-amino acid transactivation sequence is well conserved in NFAT family proteins, although the sequences contiguous to the carboxyl-terminal regions of the NFAT family are much less conserved. We also report three additional isoforms of NFATx, designated NFATx2, NFATx3, and NFATx4. This transactivation sequence is altered by tissue-specific alternative splicing in newly isolated NFATx isoforms, resulting in lower transactivation activity in Jurkat T cells. NFATx1 is expressed predominantly in the thymus and peripheral blood leukocyte, while the skeletal muscle expressed primarily NFATx2. In Jurkat cells, transcription from the NFAT site of the IL-2 promoter is activated strongly by NFATx1 but only weakly by NFATx2. These data demonstrate that the 15-amino acid sequence of NFATx1 is a major transactivation sequence required for induction of genes by NFATx1 in T cells and possibly regulates NFAT activity through tissue-specific alternative splicing.

Alternative Splicing↗

PubMed1998

A conditionally active form of STAT6 can mimic certain effects of IL-4.

Binding of IL-4 to its cognate receptor leads to the activation of a number of signaling pathways within the cell. Activation of the transcription factor STAT6 by JAK family protein tyrosine kinases has been shown to be essential for the full response of cells to IL-4. To elucidate the role of STAT6 in IL-4 signaling, we have constructed and expressed in cells a conditionally active form of the protein (STAT6:ER*) by fusing STAT6 to a modified form of the hormone-binding domain of the estrogen receptor. Activation of STAT6:ER* by 4-hydroxytamoxifen leads to specific activation of STAT6-regulated gene expression including the activation of a STAT6 reporter construct and induction of CD23 in B cell lines. Interestingly, in contrast to native STAT6, activation of STAT6:ER* occurs in the absence of detectable tyrosine phosphorylation of the fusion protein. This type of conditional system will be helpful in dissecting the mechanisms and specificity of transcriptional regulation by the STAT family of transcription factors.

Animals↗

PubMed1998

Interleukin-18 activates the IRAK-TRAF6 pathway in mouse EL-4 cells.

The pleiotropic biological activities of interleukin-18 (IL-18) are mediated by IL-18 receptor (IL-18R). When the ligand binds to the IL-18R, IL-18R initiates a signaling cascade that results in the activation of nuclear factor kappa B (NF-kappa B). When mouse EL-4 cells were exposed to IL-18, IL-1 receptor-associated kinase (IRAK) was recruited to IL-18R and was phosphorylated. In addition, tumor necrosis factor receptor-associated factor-6 (TRAF6) was associated with IRAK. Therefore, we concluded that IL-18/IL-18R-mediated signaling may share the IRAK/TRAF6 pathway through NF-kappa B activation with the IL-1/IL-1 receptor system.

Animals↗

PubMed1998

Distinct NFAT family proteins are involved in the nuclear NFAT-DNA binding complexes from human thymocyte subsets.

The nuclear factor of activated T cells (NFAT) is involved in the transcriptional induction of cytokine and other immunoregulatory genes during an immune response. Among four distinct NFAT family members identified to date, mRNAs of NFAT1, NFATc, and NFATx are expressed in the thymus. Here, we report the distribution of these three NFAT family members in human fetal thymocyte subsets and in peripheral mature T cells. We show that NFATx mRNA was expressed in all T lymphocyte subsets tested and was highest in CD4+CD8+ double positive (DP) thymocytes. Conversely, NFAT1 mRNA was preferentially expressed in the mature CD4+ single positive (SP) populations. NFATc mRNA was present at low levels in all subsets but strongly induced upon treatment with phorbol ester and calcium ionophore. Interestingly, we detected NFAT-DNA binding complexes in DP thymocytes, albeit at lower levels than in CD4 SP cells. Corresponding to the mRNA expression, we observed that NFATx was responsible for the NFAT-DNA binding in DP thymocytes. Moreover, this DNA binding was inhibited by cyclosporin A, indicating that NFATx nuclear translocation was regulated by the calcineurin phosphatase in DP thymocytes. For the CD4 SP populations, NFAT1 and NFATc, and to some extent NFATx, were responsible for the NFAT-DNA binding complexes. These results indicate that NFAT family members are differentially regulated during the development of T cells, and that NFATx may play a distinct role in calcineurin-dependent signaling in DP thymocytes.

Cell Nucleus↗

PubMed1998

Characterization of cis-regulatory elements and nuclear factors conferring Th2-specific expression of the IL-5 gene: a role for a GATA-binding protein.

Expression of the IL-5 gene is restricted to the Th2 subset of helper T cells. We have previously defined four cis-regulatory elements of the IL-5 promoter responding to PMA and cAMP in EL-4 cells. We now report that the 1.2-kb region of the IL-5 promoter directs expression of the IL-5 gene in a Th2 clone but not a Th1 clone, indicating that transcription from the IL-5 promoter is Th2 specific. For the functioning of the IL-5 promoter in a Th2 clone, IL-5C and IL-5CLE0 were critical. IL-5CLE0 interacted with both constitutive and inducible nuclear factors (designated NFIL-5CLE0), which existed in both Th1 and Th2 clones, whereas IL-5C interacted with a constitutive nuclear factor (designated NFIL-5C), which was found only in Th2 but not in Th1 clones. Th2 specificity of NFIL-5C was also confirmed using in vitro-differentiated Th1 and Th2 cells derived from TCR-transgenic mice. The sequence for NFIL-5C binding bears homology with GATA-binding sites. The NFIL-5C complex was supershifted by an anti-GATA-3 Ab and inhibited by an oligonucleotide containing GATA-binding sites. We showed preferential expression of GATA-3 in Th2 cells. Finally, we demonstrated that in vitro-translated GATA-3 bound to IL-5C and overexpression of GATA-3 augmented stimulation-dependent IL-5 promoter activity in EL-4 cells. Taken together, our results provide evidence that GATA-related factors may be involved in Th2-specific expression of the IL-5 gene.

Animals↗

PubMed1998

A study of cell death in Werdnig Hoffmann disease brain.

We examined the occurrence of apoptotic cell death in the autopsied brains of four patients with Werdnig Hoffmann disease (WH), using TdT-mediated DIG-dUTP nick end labeling (TUNEL) and immunohistochemistry for apoptosis-related proteins. Three of the four patients, aged over 6 months, exhibited TUNEL-positive cells in the lateral nuclei of the thalamus, and one of the three patients also had TUNEL-positive cells in the cerebral cortex. The labeled nuclei did not show characteristic features such as nuclear fragmentation or apoptotic bodies, and synaptophysin-positive granules were observed around some of the TUNEL-positive cells, although none of the antibodies against glial markers could visualize TUNEL-positive cells. TUNEL-positive cells were not observed in other regions examined, including the spinal cord, medulla and cerebellum or in the brains of three age-matched controls. There were neither immunopositive structures for bcl-2 or p53 nor alteration of in situ expression of bcl-xs/l or bax in any subject, and the TUNEL-positive cells lacked immunopositivity against apoptosis-related proteins. The presence of these TUNEL-positive cells might suggest latent neurodegeneration in the thalamus before central chromatolysis of neurons or neuronal loss appears, although it is not clear whether apoptotic cell death is involved in this degenerative process.

Apoptosis↗

PubMed1998

Brain tumors in surgical neuropathology of intractable epilepsies, with special reference to cerebral dysplasias.

Surgical specimens from 30 patients (13 males and 17 females) with intractable epilepsy with brain tumors and allied lesions were histopathologically examined: 4 of nonneurogenic origin (1 angiolipoma with cortical dysplasia and 3 cavernous hemangiomas), 2 low-grade fibrillary astrocytomas, 1 pleomorphic xanthoastrocytoma, 3 pilocytic astrocytomas with nuclear polymorphism, 1 oligoastrocytoma, 9 gangliogliomas, 3 gangliogliomatous lesions combined with tuberous sclerosis-like dysplastic changes, and 7 undetermined lesions suspected of being mixed glioma, dysembryoplastic neuroectodermal tumor (DNT), or dysplasia. They were all located supratentorially: in the temporal lobe in 21, frontal lobe in 6, and parietooccipital lobe in 3. The age of onset was under 20 years in most patients. Some kinds of dysplasias, such as focal cortical dysplasia, glioneuronal heterotopia, and clustered neurons in the hippocampus and amygdaloid nucleus, were combined in 11 cases, especially those with age of onset under 10 years. Pilocytic astrocytoma-like features were seen in 5 of the gangliogliomas and 3 of the undetermined lesions, and DNT-like features in 2 of the former and 3 of the latter. Gangliogliomas, pilocytic astrocytomas, mixed gliomas, DNTs, and dysplasias may be closely inter-related in the development of intractable epilepsies of young patients.

Adolescent↗

PubMed1998

Hemimegalencephaly: signal changes suggesting abnormal myelination on MRI.

We reviewed the MRI of 17 patients with hemimegalencephaly to investigate abnormal myelination in this condition. On images of seven patients aged 18 months or less, the white matter on the affected side suggested advanced myelination for the age. On T1-weighted images of three patients aged 1 month, the anterior limb of the internal capsule in the affected hemisphere was myelinated, and T1 shortening was not clearly seen in the pre- and postcentral gyri. The cortical grey matter and subcortical white matter was isointense in two patients. Images of two patients aged 4 to 5 months and of five patients aged 8-18 months showed myelination that extended more peripherally in the white matter of the affected hemisphere.

Adolescent↗

PubMed1998

Loss of the dentate nucleus neurons is associated with torpedo formation: a morphometric study in progressive supranuclear palsy and dentatorubro-pallidoluysian atrophy.

Cerebellar torpedoes can be induced by direct damage to Purkinje cell axons. This raises the possibility that the loss of dentate nucleus neurons (DNNs) may also cause torpedo formation through synaptic detachment between DNNs and Purkinje cell axon terminals. To investigate this possibility, we conducted a morphometric study with an image analyzer in progressive supranuclear palsy (PSP) and dentatorubro-pallidoluysian atrophy (DRPLA). Using horizontal and sagittal sections of the cerebellar hemispheres containing the greatest proportion of the dentate nucleus, we determined the line densities of torpedoes, Purkinje cells, and DNNs. In PSP and DRPLA, the densities of DNNs were significantly lower, and the densities of torpedoes much greater than in controls, while those of Purkinje cells were normal in both diseases. In addition, the torpedo densities in PSP and DRPLA showed a strong negative correlation with the DNN densities. Thus, this study clearly demonstrated that torpedoes are formed in association with the loss of DNNs, suggesting that they may occur in consequence of synaptic disconnection of Purkinje cells from DNNs.

Adult↗

PubMed1998

Astrocytic plaques and tufts of abnormal fibers do not coexist in corticobasal degeneration and progressive supranuclear palsy.

Corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are characterized by their unique clinical features and neuronal pathology. Although astrocytic plaques and tufts of abnormal fibers have been suggested to be specific histopathologic markers, recent studies have revealed significant clinicopathologic overlap between CBD and PSP. Based on the distinctive camera lucida profile of astrocytic inclusions on Gallyas-Braak silver staining, we found that astrocytic plaques and tufts of abnormal fibers did not coexist in the same patient among 30 cases of clinically diagnosed CBD, PSP and atypical Parkinson's disease. Using Tau immunohistochemistry it was difficult to verify the absence of tufts of abnormal fibers. A morphometric analysis revealed that the two groups classified by the presence or absence of astrocytic plaques and tufts of abnormal fibers exhibited significant differences in the density of ballooned neurons and neurofibrillary tangles and degeneration of the subcortical nuclei. Assessment using the NINDS neuropathologic criteria revealed that the cases with astrocytic plaques and tufts of abnormal fibers closely correspond to CBD and typical PSP, respectively. In addition, the cases lacking either of these two astrocytic inclusions had atypical PSP according to the NINDS criteria, and were associated with novel tau-positive astrocytes (spiny astrocytes). We thus conclude that astrocytic plaques and tufts of abnormal fibers are highly characteristic structures for CBD and typical PSP, respectively. We emphasize the importance of strict differentiation between different astrocytic inclusions not only for diagnosis, but also for further studies for elucidation of their role in the disease mechanisms of CBD and PSP.

Aged↗

PubMed1998

Study on surgical treatment of intractable childhood epilepsy.

We studied the clinical details of 14 children with intractable epilepsies, all of whom underwent epilepsy surgery before age 18 years. All 14 suffered catastrophic seizures, which were resistant to the full range of available medical treatments. The ages at operation ranged from 4 years 7 months to 17 years 2 months, with a mean of 9 years 11 months. In nine patients, the age at onset of epilepsy was less than 2 years. The seizure disorders were classified as temporal lobe epilepsy in two patients, extratemporal lobe epilepsy in 10, and symptomatic generalized epilepsy in two. Eight patients had a hemicorporeal deficit (hemiparesis or hemiplegia) preoperatively. All 14 patients showed localized magnetic resonance imaging (MRI), single photon emission computer tomography (SPECT) and/or positron emission tomography (PET) abnormalities, providing crucial information regarding the epileptic focus. As to the surgical outcomes, four patients became seizure-free and the other 10 showed significant improvement during a mean follow-up period of 2 years 5 months. As to etiology, cortical dysplasia was identified in seven patients. Epilepsy surgery should be considered for intractable childhood epilepsy based on individual clinical characteristics, including seizure status, cognitive development, and evidence indicating location of the seizure focus, rather than age.

Adolescent↗

PubMed1998

Signalling into the T-cell nucleus: NFAT regulation.

The nuclear factor of activated T cells (NFAT) plays an important role in T-cell biology. Activation of T cells results in the rapid calcineurin-dependent translocation of NFAT transcription factors from the cytoplasm to the nucleus. This translocation process coupled to the subsequent active maintenance of NFAT in the nucleus compartment is critical for the induction of expression of several genes encoding cytokines and membrane proteins that modulate immune responses. The molecular cloning of the NFAT family of transcription factors has facilitated rapid progress in the understanding of the signalling mechanisms that control the activity of NFAT.

Amino Acid Sequence↗

PubMed1998

Autoimmune enteropathy with severe atrophic gastritis and colitis in an adult: proposal of a generalized autoimmune disorder of the alimentary tract.

BACKGROUND: We describe the case of an adult with autoimmune enteropathy consistent with both severe atrophic gastritis accompanying antral stenosis and colitis. METHODS AND RESULTS: The patient, positive for anti-intrinsic factor antibody, had intractable diarrhea and protein-losing enteropathy. In the ileum inflammatory cells were observed infiltrating the lamina propria along with villus atrophy, and similar inflammation was also found in the lamina propria of the colon and stomach, with complete loss of specialized glands. The myenteric ganglion cells of the hypertrophied muscularis propria in the stenosed antrum showed degeneration with surrounding T-lymphocyte infiltration. There were more CD8+ than CD4 lymphocytes in the lamina propria of the stomach and colon. CONCLUSIONS: The CD8+ (suppressor-cytotoxic) T lymphocytes may have played an important role in the production of lesions in the stomach, small intestine, and colon, so we propose this case as an example of a generalized autoimmune disorder of the alimentary tract.

Autoimmune Diseases↗

PubMed1998

Th2-specific DNase I-hypersensitive sites in the murine IL-13 and IL-4 intergenic region.

IL-4 and IL-13 are cytokines preferentially produced by Th2 cells, and their genes are located in close proximity on human chromosome 5 and mouse chromosome 11. To identify potential regulatory elements that confer Th2-specific expression of IL-4 and IL-13 genes, we constructed a physical map of the IL-13/IL-4 locus and conducted DNase I-hypersensitive (DH) site analysis using Th clones and in vitro-differentiated effector Th cells obtained from TCR transgenic mice. Three DH sites, HSS1, HSS2 and HSS3, were identified within the intergenic region between IL-13 and IL-4 genes. HSS3 was observed both in Th1 and Th2 cells as well as CD4+ naive T cells, while HSS1 and HSS2 were detected exclusively in Th2 cells. The correlation between differentiation into Th2 subtype and the appearance of HSS1 and HSS2 suggests that these regions may play a role in subtype-specific expression of the IL-13/IL-4 locus.

3' Untranslated Regions↗