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K Arai

Publications and source records attributed to K Arai.

At least 451 records · Page 25Linked to original sources
PubMed1994

Transformation from SAA2-fibrils to AA-fibrils in amyloid fibrillogenesis: in vivo observations in murine spleen using anti-SAA and anti-AA antibodies.

Early amyloid fibrillogenesis from serum amyloid A protein (SAA) has been observed in the murine spleen after an injection of casein-Freund's complete adjuvant in the presence of amyloid enhancing factor, using anti-SAA C-terminal (anti-SAA) and anti-amyloid A (AA) antibodies. In Western immunoblotting of sera, both SAA1 and SAA2 reached a maximum after 24 h and began to decrease after 48 h. In spleen extracts, SAA2, but not SAA1 or AA, was found from 48 h, when amyloid was first deposited in the marginal zone. Electron microscopic immunohistochemistry of this stage showed reaction products from SAA in the marginal zone as fine granules along the cell membrane of mononuclear cells and focal intercellular aggregates, which contained fine fibrils originating from the cell membrane. Amyloid nodules, surrounded by mononuclear cells, developed from this stage. In the nodules, fibrils were positive for anti-SAA only in the vicinity of the cell membrane, while anti-AA stained fibrils throughout. Our hypothesis for fibrillogenesis is thus as follows: Serum SAA2 is specifically deposited on mononuclear cells in the marginal zone and polymerized extracellularly into fibrils, retaining its antigenicity (SAA2 amyloid fibrils); these fibrils are then processed to AA amyloid fibrils in situ by cleavage of the C-terminal portion of SAA2.

Amyloidosis↗
PubMed1994

TM-1 cells from an established human malignant glioma cell line produce PDGF, TGF-alpha, and TGF-beta which cooperatively play a stimulatory role for an autocrine growth promotion.

We have previously established a human malignant glioma cell line, TM-1. TM-1 cells could proliferate in the serum-free medium. In the present study, immunochemical analysis demonstrated that platelet-derived growth factor (PDGF), transforming growth factor (TGF)-alpha, and TGF-beta are present in the serum-free medium conditioned by growing TM-1 cells. While the cells appeared to possess a single type of binding sites for epidermal growth factor (EGF) with properties comparable to those determined for other tumor cells, the conditioned medium did not contain EGF.PDGF, TGF-alpha, and EGF added exogenously to serum-free media stimulated thymidine incorporation into DNA of TM-1 cells. In addition, antibodies specific for PDGF and TGF-alpha suppressed this activity. These results indicate autocrine and stimulatory roles of PDGF and TGF-alpha for the proliferation of TM-1 cells. As observed for other tumor cells, TGF-beta by itself weakly suppressed thymidine incorporation by TM-1 cells. However, TGF-beta employed in combination with TGF-alpha or EGF appeared to stimulate thymidine incorporation, suggesting that a cooperative action of TGF-beta with different growth factors may be involved in the stimulatory growth regulation at least for TM-1 cells.

Cell Division↗
PubMed1994

Signals and nuclear factors that regulate the expression of interleukin-4 and interleukin-5 genes in helper T cells.

Mouse thymoma line EL-4 cells produce cytokines such as interleukin (IL)-2, IL-3, IL-4, IL-10, and granulocyte-macrophage colony-stimulating factor in response to phorbol 12-myristate 13-acetate (PMA). EL-4 cells also produce low levels of IL-5 when stimulated by PMA alone; however, cAMP greatly augments PMA-dependent IL-5 production. A transient transfection assay revealed that two signals, PMA and cAMP, are required for optimal activation of the IL-5 promoter. In contrast, cAMP almost completely inhibited the PMA-dependent activation of the endogenous IL-2 gene, as well as the transfected IL-2 promoter. These results indicate that the IL-5 gene is positively regulated by cAMP in a manner opposite to that for the IL-2 gene. One of the nuclear factors (NFs) that regulates the response of the IL-5 promoter to cAMP and PMA has properties similar to NF for activated t cell. The P sequence of the IL-4 gene, defined as a responsive element for PMA and calcium ionophore (A23187), shares sequence similarity with the NF kappa B and the NF-activated T cell binding sites. We attempted to determine whether NF(P), a nuclear factor specific for the P sequence, is related to NF-kappa B and nuclear factor for activated T cell (NF-AT). In electromobility shift assays both NF-kappa B (P65 or P65/P50 heterodimer) and NF-AT bound to the P sequence. However, sequence specificity of NF-AT was more similar to that of NF(P), and only a small amount of P65 was detected in NF(P). These results indicate that a component or components of NF-AT have the potential to reconstitute NF(P), whereas NF-kappa B alone does not account for NF(P) in Jurkat crude extract. Taken together, these results suggest that NF-AT-like factors are involved in the regulation of IL-4 and IL-5 genes.

Animals↗
PubMed1994

Activation of early response genes and cell proliferation by human interleukin-3, granulocyte-macrophage colony-stimulating factor, and interleukin-5 receptors: comparison with human interleukin-4 receptor signaling.

Interleukin (IL)-3, granulocyte-macrophage colony-stimulating factor, and IL-5 receptors (IL-3R, GMR, and IL-5R) are composed of the alpha chain specific to each and the common beta chain, and both the alpha and beta subunits are members of the cytokine receptor superfamily. We previously showed that the high-affinity human GMR reconstituted by cotransfecting the alpha and beta chain cDNA clones transduces signals in response to hGM-CSF to activate transcription of c-fos, c-jun, and c-myc proto-oncogenes in mouse proB cell line BA/F3 or in mouse fibroblast NIH3T3 cells. These results indicated that molecules, such as tyrosine kinase, unique to hematopoietic cells are not essential to transduce signals. In this study, the function of the alpha subunit of GMR was compared with those of IL-3R and IL-5R by cotransfecting human cDNAs encoding the alpha subunit of IL-3R or IL-5R and the common beta subunit into BA/F3 or NIH3T3 cells. We found that the reconstituted human IL-3R, in response to hIL-3, transduced signals to activate transcription of c-fos promoter and induced DNA synthesis in both types of cells in a manner similar to hGMR. Likewise, hIL-5 activates c-fos promoter in transfected NIH3T3 cells expressing hIL-5R. These results indicated that the alpha subunits of IL-3R and IL-5R have properties similar to those of the GMR alpha subunit. In contrast, transfected human IL-4 receptor (hIL-4R) cDNA, which weakly activated c-fos promoter and induced DNA synthesis in BA/F3 cells, failed to elicit these activities in NIH3T3 cells in response to hIL-4.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1994

Hormone-nuclear receptor interactions in health and disease. Glucocorticoid resistance.

Familial glucocorticoid resistance results from the partial inability of glucocorticoids to exert their effects on their target tissues throughout the organism. The condition is associated with compensatory elevations of circulating ACTH and cortisol, with the former causing excess abnormal secretion of steroids with mineralocorticoid and androgen activity. The manifestations of glucocorticoid resistance vary from asymptomatic to chronic fatigue, to varying degrees of hypertension and/or hypokalaemic alkalosis and hyperandrogenism. The latter can be manifest in women as acne, hirsutism, menstrual irregularity, oligoanovulation and infertility, in men as infertility, and in children as precocious puberty. Different molecular defects of the highly conserved glucocorticoid receptor gene, altering its concentration and functional characteristics, appear to cause the syndrome of familial glucocorticoid resistance. Depending on the molecular defect, this syndrome is transmitted by an autosomal dominant or recessive trait. There are recent suggestions that non-generalized forms of glucocorticoid resistance may exist, resulting in autoimmune-inflammatory phenomena or psychiatric manifestations.

Drug Resistance↗
PubMed1994

Calcineurin potentiates activation of the granulocyte-macrophage colony-stimulating factor gene in T cells: involvement of the conserved lymphokine element 0.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2) are produced by stimulation with phorbol-12-myristate acetate (PMA) and calcium ionophore (A23187) in human T cell leukemia Jurkat cells. The expression of GM-CSF and IL-2 is inhibited by immunosuppressive drugs such as cyclosporin A (CsA) and FK506. Earlier studies on the IL-2 gene expression showed that overexpression of calcineurin (CN), a Ca2+/calmodulin-dependent protein phosphatase, can stimulate transcription from the IL-2 promoter through the NF-AT-binding site. In this study, we obtained evidence that transfection of the cDNAs for CN A (catalytic) and CN B (regulatory) subunits also augments transcription from the GM-CSF promoter and recovers the transcription inhibited by CsA. The constitutively active type of the CN A subunit, which lacks the auto-inhibitory and calmodulin-binding domains, acts in synergy with PMA to activate transcription from the GM-CSF promoter. We also found that the active CN partially replaces calcium ionophore in synergy with PMA to induce expression of endogenous GM-CSF and IL-2. By multimerizing the regulatory elements of the GM-CSF promoter, we found that one of the target sites for the CN action is the conserved lymphokine element 0 (CLE0), located at positions between -54 and -40. Mobility shift assays showed that the CLE0 sequence has an AP1-binding site and is associated with an NF-AT-like factor, termed NF-CLE0 gamma. NF-CLE0 gamma binding is induced by PMA/A23187 and is inhibited by treatment with CsA. These results suggest that CN is involved in the coordinated induction of the GM-CSF and IL-2 genes and that the CLE0 sequence of the GM-CSF gene is a functional analogue of the NF-AT-binding site in the IL-2 promoter, which mediates signals downstream of T cell activation.

Animals↗
PubMed1994

Effects of prostaglandin E2 on Th0-type human T cell clones: modulation of functions of nuclear proteins involved in cytokine production.

The effects of prostaglandin E2 (PGE2) on cytokine production and proliferation of the CD4+ human helper T cell clone SP-B21 were investigated. In cells stimulated with anti-CD3 mAb, PGE2 inhibited cell proliferation and the production of all the cytokines examined. Addition of rIL-2 fully restored the proliferative response and partially restored the production of IL-4 and IL-5, but not that of other cytokines. In contrast, in cells stimulated with phorbol myristate acetate (PMA)/A23187, PGE2 enhanced the production of IL-4 and IL-5, and only partially inhibited the production of other cytokines. Therefore, the effects of PGE2 vary depending on the mode of T cell activation, and the IL-4 and IL-5 are regulated differently from other cytokines. In a mobility shift assay, only the NF-kappa B (p50/p50) homodimer was observed in a complex formed with the kappa B sequence in unstimulated SP-B21 cells. When cells were stimulated with anti-CD3 mAb or PMA/A23187, a complex formation of NF-kappa B (p50/p65) heterodimer with the kappa B sequence was induced. Interestingly, PGE2 or di-butyryl (Bt2)cAMP abolished the binding of NF-kappa B (p50/p65) heterodimer to the kappa B sequence in cells stimulated with anti-CD3 mAb but not with PMA/A23187. Our results suggest that the target of PGE2 action is a component in the signal transduction pathway leading to the activation of protein kinase C. However, the inhibition of the T cell activation signals by PGE2 is selective. PGE2 enhanced the complex formation with NF-AT, AP-1 and CLE0 sequences when the cells were activated by either anti-CD3 mAb or PMA/A23187 stimulation. It seems therefore that PGE2, by elevating cAMP levels, interferes with the activation pathway for NF-kappa B but not for NF-AT, AP-1 or CLE0 binding protein.

Base Sequence↗
PubMed1994

Combined paraumbilical perforator skin flap and vascularized pubic bone graft.

A severely depressed deformity of the buccal region was repaired with an osteocutaneous flap based on the deep inferior epigastric vessels. This osteocutaneous flap has not been previously described in the literature. The superior pubic ramus, supplied by pubic branches from the deep inferior epigastric vessels, forms the bony portion of the combined flap. The cutaneous portion is also supplied by the deep inferior epigastric vessels and its thickness can be adjusted. This combination is useful when requiring both a thin flap and a flat bone.

Adult↗
PubMed1994

A similar expression pattern of adhesion molecules between intermediate TCR cells in the liver and intraepithelial lymphocytes in the intestine.

Two major populations of extrathymically differentiated T cells exist in the liver and intestine. Such T cells in the liver have TCR of intermediate intensity (i.e., intermediate TCR cells) and constitutively express IL-2 receptor beta-chain (IL-2R beta), whereas those in the intestine, especially intraepithelial lymphocytes, have TCR of bright intensity, consisting of a mixture of IL-2R beta+ and IL-2R beta-. All mature thymocytes and thymus-derived T cells seen in the peripheral immune organs are TCR-bright+ IL-2R beta- under resting conditions. When the expression pattern of adhesion molecules, including CD44, L-selectin, LFA-1 and ICAM-1, was compared among these T-cell populations, they displayed quite unique patterns of expression. All extrathymic T cells in the liver, intestine, and even other organs were CD44+ L-selectin-LFA-1++ICAM-1+, whereas thymocytes and thymus-derived T cells were CD44-L-selectin+LFA-1+ICAM-1-. This inverted expression of adhesion molecules between extrathymic T cells and thymus-derived T cells might be associated with their unique tissue-localization.

Animals↗
PubMed1994

Opposing effects of indomethacin and nordihydroguaiaretic acid on macrophage function and tumor growth.

The effects of indomethacin (INDO) and nordihydroguaiaretic acid (NDGA) were compared on macrophage function and tumor growth. Intraperitoneal injections (5 mg/kg/day, 6, 8 or 9 days) of INDO in C57BL/6 mice stimulated the cytotoxicity of peritoneal macrophages and inhibited growth of subcutaneous B16 melanoma, whereas NDGA injections suppressed macrophage cytotoxicity, increased macrophage prostaglandin-E2 (PGE2) release, and enhanced the tumor growth. Further, pretreatment of macrophages in vitro with the INDO group serum increased cytostasis against B16 tumor cells, while the use of NDGA group serum reduced it. Incubation of tumor-bearer's macrophages in vitro with INDO (10(-6) M and 10(-7) M) or 10(-6) M NDGA for 4 h reduced PGE2 release, but 10(-7) M NDGA markedly enhanced the PGE2 release. Our data indicate that INDO and NDGA are able to modulate the macrophage function directly, and produce opposing effects on macrophage function and tumor growth. Inhibitory actions of INDO and NDGA on the cyclooxygenase or lipoxygenase pathway of arachidonic acid metabolism appear to contribute to their effects.

Animals↗
PubMed1994

Molecular cloning of a novel human cDNA encoding a zinc finger protein that binds to the interleukin-3 promoter.

The CT/GC-rich region (-76 to -47) is one transcriptional regulatory region of the interleukin-3 (IL-3) gene which confers basic transcriptional activity and responds to trans-activation by human T-cell leukemia virus type I-encoded Tax. We isolated three types of cDNAs encoding Cys2/His2-type zinc finger proteins that bind to this region. Two were identical to known transcription factors, EGR1 and EGR2, and the other clone, named DB1, encoded a novel protein of 516 amino acids with six zinc finger motifs. DB1 mRNA was present in human tissues, ubiquitously. Two constitutive transcripts of 4.0 and 4.8 kb in length were present in Jurkat cells. Electrophoretic mobility shift assay, with specific antibodies, showed that DB1 constitutively binds to this region whereas EGR1 binds in a T-cell activation-dependent manner. Overexpression of DB1 in Jurkat cells had no detectable effect on the transcription activity of the IL-3 promoter, in a transient-transfection assay. EGR1 and EGR2 increased IL-3 promoter activity when the transfected cells were stimulated with phorbol-12-myristate-13-acetate and A23187. When DB1 was cotransfected with a Tax expression vector, transcription activity of the IL-3 promoter induced by Tax was significantly increased, while EGR1 and EGR2 were without effect. These results suggest that EGR1 has a role in inducible transcription of the IL-3 gene, while DB1 sustains basal transcriptional activity and also cooperates with Tax to activate the IL-3 promoter.

Amino Acid Sequence↗
PubMed1994

Estradiol transcriptionally and posttranscriptionally up-regulates thyrotropin-releasing hormone receptor messenger ribonucleic acid in rat pituitary cells.

17 beta-Estradiol (E2) has been shown to up-regulate the binding activity of the TRH receptor in rat pituitary cells. In this report, we investigated whether and how E2 alters TRH receptor expression at the mRNA level using the oocyte mRNA expression system, Northern blot analysis, and nuclear run-on assay. In oocytes injected with mRNA from the anterior pituitaries or GH3 cells, a TRH-induced 45Ca2+ efflux appeared. This efflux was dependent on the amount of TRH and injected RNA, and was inhibited by simultaneous addition of chloridazepoxide, an antagonist of the TRH receptor. Treatment of GH3 cells with E2 increased TRH receptor mRNA activity, as assessed in the oocyte expression system; the E2 effect became apparent after 3 h of treatment and reached a maximum (3- to 4-fold) between 6-72 h after addition. Northern blot analysis with a 412-basepair cDNA fragment or 3.7-kilobasepair full-length cDNA of the TRH receptor as a probe showed that E2 maximally (5-fold) increased the TRH receptor mRNA level of GH3 cells, with a half-maximal concentration of 0.1 nM after 6 h of treatment. The elevated level of mRNA induced by E2 was augmented, rather than impeded, by cycloheximide, indicating that ongoing protein synthesis was not required for the induction. The rate of transcription of the TRH receptor gene in isolated nuclei taken from GH3 cells was increased 3-fold by 2 h of treatment with E2. Furthermore, the half-life of the TRH receptor mRNA in GH3 cells was prolonged by E2 (from 2.3 to 4.4 h). These results demonstrate that E2 up-regulates the TRH receptors of the pituitary cells at the mRNA level by increasing both the transcription rate and stability.

Animals↗
PubMed1994

Physiological and molecular aspects of mineralocorticoid receptor action in pseudohypoaldosteronism: a responsiveness test and therapy.

Pseudohypoaldosteronism (PHA), characterized by congenital resistance to aldosterone and excessive salt loss, has been traditionally treated with salt replacement. Although the mineralocorticoid receptor (MR) has been suggested as a potential locus of the defect in this disease, no such abnormality has been identified as yet. We studied a 17-yr-old male patient with congenital multifocal target organ resistance to aldosterone. Both carbenoxolone, an 11 beta-hydroxysteroid dehydrogenase inhibitor, and a high dose of fludrocortisone normalized the patient's serum electrolyte concentrations and decreased his urinary excretion of sodium, suggesting that this patient's resistance was partial and could be overcome by high concentrations of endogenous or exogenous mineralocorticoids. We hypothesized that the beneficial effect of these treatments was mostly mediated by the MR, because the administration of dexamethasone, while this patient was receiving a therapeutic dose of carbenoxolone, caused its reversal. These findings convinced us that there was functional, albeit possibly defective, MR in this patient and led us to perform molecular studies. Both alleles of the MR gene were expressed in the patient and his clinically and biochemically normal father. A conservative heterozygous mutation (A760-->G760, Ileu180-->Val180) and a nonconservative homozygous mutation (C944-->T944, Ala241-->Val241) were identified in the complementary DNA of both the patient and his father. The first untranslated exon and 0.9 kilobase of the 5'-regulatory region were also identical in the two men. It appears that the mutations causing amino acid substitutions represent polymorphisms, as we found high frequencies of both in the general population. We conclude that carbenoxolone and fludrocortisone may help define the presence of functional MR in patients with PHA and that the former could be used in the long term therapy of this disease. We hypothesize that the defect causing PHA in this patient might be in a post-MR step of aldosterone action.

Adolescent↗
PubMed1994

Inhibitory activities of metal chelators on endothelin-converting enzyme. I. In vitro studies.

The effects of various metal chelators on endothelin (ET)-converting enzyme (ECE) activity were examined in vitro. Three chelators, 2,3-dimercapto-1-propanol (DMP), toluene-3,4-dithiol (TDT) and 8-mercaptoquinoline (8-MQ), were found to dose-dependently inhibit ECE activity, but this inhibition was much weaker compared with EDTA. In the presence of Zn2+, the inhibitory activity of all these compounds, including EDTA, was abolished. The addition of Ca2+ and Mg2+ markedly attenuated the inhibitory activity of EDTA, but the other three chelators were still able to inhibit ECE. ECE, once inactivated by EDTA or 8-MQ, was reactivated by the addition of divalent cations such as Zn2+ and Mn2+. These compounds also inhibited angiotensin-converting enzyme activity in a manner similar to the inhibition exhibited towards ECE. Chelate-titration indicated that DMP, TDT and 8-MQ chelate Zn2+ but not Ca2+ and Mg2+. These results suggest that the ECE inhibition exhibited by these compounds is mainly attributable to their chelating activities. The metal-selective chelating activity by DMP, TDT and 8-MQ may contribute to the retention of ECE inhibition in the presence of Ca2+ and Mg2+.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Inhibitory activities of metal chelators on endothelin-converting enzyme. II. In vivo studies.

The effects of metal chelators on endothelin (ET)-converting enzyme (ECE) activity in vivo were examined. Three compounds, (2,3-dimercapto-1-propanol (DMP), toluene-3,4-dithiol (TDT) and 8-mercaptoquinoline (8-MQ)), which inhibited ECE in in vitro studies, exhibited inhibitory activity towards big ET-1-induced sudden death in mice, while EDTA did not. Similar results were obtained in big ET-1-induced hypertension. Big ET-1-induced hemoconcentration was inhibited by pretreatment with 8-MQ or EDTA but not with DMP or TDT. The elevation of immunoreactive ET-1 (IR-ET-1) in plasma after administration of big ET-1 was inhibited by pretreatment with the three compounds but not by EDTA. On the other hand, no chelator inhibited the elevation of IR-ET-1 in lung tissue after injection of big ET-1. Taking into consideration the in vitro results, more selective chelating activity of the compounds towards Zn2+ rather than Ca2+ and Mg2+ may contribute to the inhibition of big ET-1-induced responses in vivo. The ET-1 formation involved in big ET-1-induced hemoconcentration may have different physiological characteristics from that involved in big ET-1-induced sudden death or hypertension.

Animals↗
PubMed1994

Digestion of endothelin-1 on cultured vascular smooth muscle cells.

The degradation of 125I-endothelin-1 (125I-ET-1) was examined on cultured porcine aortic endothelial cell (EC) and rat vascular smooth muscle cell (SMC) by HPLC analysis. The degradation of ET-1 was observed on SMC and was slightly observed on EC. Membrane fractions of SMC had a strong potency for the degradation of ET-1 and retained activity even in plasma. This activity was inhibited with some of the noble inhibitors which were known as enkephalinase inhibitors. These results suggest that endothelin degradation enzyme on SMC is related to enkephalinase and that this enzyme plays a significant role in the degradation of ET-1 in vivo.

Animals↗