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M Kitaura

Publications and source records attributed to M Kitaura.

17 recordsLinked to original sources
PubMed1997

Molecular cloning of a novel human CC chemokine EBI1-ligand chemokine that is a specific functional ligand for EBI1, CCR7.

By searching the expressed sequence tag (EST) data base, we identified partial cDNA sequences encoding a novel human CC chemokine. We determined the complete cDNA sequence that encodes a highly basic polypeptide of a total 98 amino acids with 20 to 30% identity to other human CC chemokines. We termed this novel chemokine from EBI1-Ligand Chemokine as ELC (see below). The ELC mRNA was most strongly expressed in the thymus and lymph nodes. Recombinant ELC protein was expressed as a fusion protein with the Flag tag (ELC-Flag). For receptor-binding assays, recombinant ELC protein fused with the secreted form of alkaline phosphatase (SEAP) was used. By stably expressing five CC chemokine receptors (CCR1 to 5) and five orphan receptors, ELC-SEAP was found to bind specifically to an orphan receptor EBI1. Only ELC-Flag, but not MCP-1, MCP-2, MCP-3, eotaxin, MIP-1alpha, MIP-1beta, RANTES (regulated on activation normal T cell expressed and secreted), thymus and activation-regulated chemokine (TARC), or liver and activation-regulated chemokine (LARC), competed with ELC-SEAP for EBI1. ELC-Flag-induced transient calcium mobilization and chemotactic responses in EBI1-transfected cells. ELC-Flag also induced chemotaxis in HUT78 cells expressing endogenous EBI1 at high levels. By somatic hybrid and radiation hybrid analyses, the gene for ELC (SCYA19) was mapped to chromosome 9p13 instead of chromosome 17q11.2 where the genes for CC chemokines are clustered. Taken together, ELC is a highly specific ligand for EBI1, which is known to be expressed in activated B and T lymphocytes and strongly up-regulated in B cells infected with Epstein-Barr virus and T cells infected with herpesvirus 6 or 7. ELC and EBI1 may thus play roles in migration and homing of normal lymphocytes, as well as in pathophysiology of lymphocytes infected with these herpesviruses. We propose EBI1 to be designated as CCR7.

Amino Acid Sequence↗
PubMed1996

Identification of a mouse eosinophil receptor for the CC chemokine eotaxin.

The CC chemokine eotaxin is a selective chemoattractant for eosinophils in vitro and induces eosinophil migration in vivo. Here we show that the mouse orphan receptor previously named macrophage inflammatory protein-1 alpha receptor-like 2 is a functional eotaxin receptor. For consistency with other nomenclature, we have renamed the receptor mouse CC chemokine receptor 3. Human and mouse eotaxin, but not other chemokines, induced transient increases in [Ca2+]i in human embryonic kidney 293 cells expressing the receptor. RNA for the receptor was abundant in primary eosinophils, but at low levels in neutrophils and macrophages. These properties make this receptor the best known candidate to mediate mouse eosinophil responses to eotaxin.

Animals↗
PubMed1996

Molecular cloning of human eotaxin, an eosinophil-selective CC chemokine, and identification of a specific eosinophil eotaxin receptor, CC chemokine receptor 3.

The CC chemokine eotaxin is a selective chemoattractant for guinea pig eosinophils, first purified from bronchoalveolar lavage fluid in a guinea pig model of allergic airway inflammation. We have now isolated the gene and cDNA for a human counterpart of eotaxin. The gene maps to chromosome 17 and is expressed constitutively at high levels in small intestine and colon, and at lower levels in various other tissues. The deduced mature protein sequence is 66% identical to human monocyte chemoattractant protein-1, and 60% identical to guinea pig eotaxin. Recombinant human eotaxin produced in insect cells induced a calcium flux response in normal human eosinophils, but not in neutrophils or monocytes. The response could not be desensitized by pretreatment of eosinophils with other CC chemokines, suggesting a unique receptor. In this regard, we show that human eotaxin is a potent and highly specific agonist for CC chemokine receptor 3, a G protein-coupled receptor selectively expressed in human eosinophils. Thus eotaxin and CC chemokine receptor 3 may be host factors highly specialized for eosinophil recruitment in inflammation, and may be good targets for the development of selective drugs for inflammatory diseases where eosinophils contribute to pathogenesis, such as asthma.

Amino Acid Sequence↗
PubMed1995

Vitamin D receptor contains multiple dimerization interfaces that are functionally different.

The vitamin D receptor mediates the signal of 1 alpha, 25-dihydroxyvitamin D3 by binding to vitamin D responsive elements in DNA as a homodimer or as a heterodimer composed of one vitamin D receptor subunit and one retinoid X receptor subunit. We have mapped the dimerization interfaces of the vitamin D receptor that is involved in homo- or heterodimer formation in the absence of DNA. While deletion of the first zinc finger region of vitamin D receptor diminished homodimerization activity, it did not affect heterodimerization. In contrast, a deletion just beyond the zinc finger region affected heterodimerization with retinoid X receptor, but not homodimerization. The zinc finger region alone could form a homodimer with full-length vitamin D receptor, but not a heterodimer with retinoid X receptor. The carboxy-terminal region was also necessary for heterodimer formation. This region showed only a weak dimerization activity in the absence of ligand, but this was dramatically increased in the presence of ligand for both homo- and heterodimerization. These results suggest that the vitamin D receptor has at least three dimerization interfaces whose functions are apparently distinguishable. These are located in the first zinc finger region, the region just beyond this zinc finger and in the carboxy-terminal region.

Amino Acid Sequence↗
PubMed1994

Difference and similarity of DNA sequence recognized by VDR homodimer and VDR/RXR heterodimer.

Nuclear receptors for the thyroid hormone and vitamin A and D cooperate with the retinoid X receptor (RXR) in activating the transcription. Although the hormone response elements for these receptors have been proposed in which spacing of the direct repeated motifs determine the specificity (so called 3-4-5 rule), vitamin D response elements (VDREs) in the natural context consist of often imperfect direct repeats. Vitamin D receptor (VDR) alone can bind to the mouse osteopontin (mSPP-1) VDRE, which contains a direct repeat separated by 3 nucleotides, but not to the rat osteocalcin (rOST) VDRE having inexact direct repeat. The presence of RXR not only allows the VDR to bind to the rOST VDRE, but also increases the binding affinity for the mSPP-1 VDRE. The RXR/VDR heterodimer exhibits the similar affinity constants for the mSPP-1 VDRE and the rOST VDRE, in spite of the apparently different affinities for two VDREs of the VDR homodimer. A random oligonucleotide selection procedure revealed that the consensus sequence selected by the RXR homodimer is the direct repeat spaced by one A residue. In contrast, the sequences preferentially selected by the VDR homodimer and the VDR/RXR heterodimer are similar, which are the direct repeats spaced by 3 nucleotides. The difference and similarity of DNA sequence recognition are discussed.

Animals↗
PubMed1993

Vitamin D receptor zinc finger region binds to a direct repeat as a dimer and discriminates the spacing number between each half-site.

1 alpha,25-Dihydroxyvitamin D3, the most active metabolite of vitamin D3, is a multifunctional agent. The actions of 1 alpha,25-dihydroxyvitamin D3 are mediated through its receptor that activates the specific genes in a ligand-dependent manner. In order to investigate the details of DNA binding properties of vitamin D receptor, we have developed the overexpression and purification system of vitamin D receptor DNA binding domain. The purified peptide could specifically bind to the osteopontin-derived vitamin D responsible element (VDRE) but not to the osteocalcin and the calbindin D-9k-derived VDREs, as determined by bandshift analysis. The osteopontin VDRE contains a direct repeat of GGTTCA motif separated by 3 nucleotides, whereas the osteocalcin and calbindin D-9k VDREs have inadequate direct repeat. Further analyses using synthetic oligonucleotides revealed that vitamin D receptor DNA binding domain could discriminate the spacing number between the consensus steroid-responsible element motif and had different affinities to direct repeats that consisted of various related sequences. These studies give insight into ways in which vitamin D receptor mediates the signal of 1 alpha,25-dihydroxyvitamin D3.

Animals↗
PubMed1992

Suppression of macrophage Ia antigen expression by endogenous interferon-alpha/beta.

Exogenous interferon-alpha (IFN-alpha) and interferon-beta (IFN-beta) (type I IFNs) are known to suppress the IFN-gamma-dependent expression of class II MHC (Ia) antigens on macrophages (M phi). We report here that the endogenous type I IFNs produced by M phi in response to IFN inducers regulate Ia expression of the M phi themselves. Coculture of M phi with IFN-gamma and polyinosinic-polycytidylic acid [poly(I):poly(C)] resulted in the reduction of Ia expression in comparison with those cultured without poly(I):poly(C). Pretreatment of M phi with poly(I):poly(C) or a bacterial lipopolysaccharide (LPS), which is also a potent IFN inducer, in vitro or in vivo, before being exposed to IFN-gamma was also effective in suppressing the Ia expression. Such suppression was abolished by the addition of anti-IFN-alpha/beta antibodies to the M phi culture along with IFN-gamma. M phi cultured with L-cell conditioned medium (LCM) containing M-CSF were less capable of expressing Ia antigens than those cultured without LCM. The Ia-expressing ability of LCM-treated M phi was also restored by the addition of anti-IFN-alpha/beta antibodies. M phi in the early stage of sterile inflammation were less responsive to IFN-gamma than those in the late stage. These results suggest that endogenous type I IFNs, which are produced in response to natural or synthetic IFN-inducers, regulate M phi Ia expression in an autocrinal manner.

Animals↗
PubMed1990

Interferon-alpha and interferon-beta induce Ia expression in limited protein synthesis condition.

We investigated the regulatory effect of interferons (IFNs) on macrophage (m phi) Ia antigen expression. Unlike type II IFN (IFN-gamma), type I IFNs (IFN-alpha and IFN-beta) were incapable of inducing the accumulation of Ia mRNA. However, when cultured with type I IFN plus cycloheximide (CHX), M phi accumulated significant amounts of Ia-specific mRNA, which was translated into Ia molecules expressed on the cell surface after the removal of CHX. Significant enhancement of Ia mRNA accumulation and the Ia expression were observed also in M phi stimulated with IFN-gamma plus CHX. Type I IFNs suppressed IFN-gamma-dependent Ia expression through the inhibition of Ia mRNA accumulation, but such suppression was not directed to the post-transcriptional step in M phi that had accumulated Ia mRNA in response to stimulation by type I or type II IFN plus CHX. These results seem to indicate that type I IFNs can induce Ia mRNA accumulation but that they also induce some inhibitory protein, the synthesis of which precedes it and is dominant, so that the Ia expression is masked.

Animals↗
PubMed1989

Suppression of macrophage Ia antigen expression by endogenous interferon-alpha/beta.

Exogenous interferon-alpha (IFN-alpha) and interferon-beta (IFN-beta) (type I IFNs) are known to suppress the IFN-gamma-dependent expression of class II MHC (Ia) antigens on macrophages (M phi). We report here that the endogenous type I IFNs produced by M phi in response to IFN inducers regulate Ia expression of the M phi themselves. Coculture of M phi with IFN-gamma and polyinosinic-polycytidylic acid [poly(I):poly(C)] resulted in the reduction of Ia expression in comparison with those cultured without poly(I):poly(C). Pretreatment of M phi with poly(I):poly(C) or a bacterial lipopolysaccharide (LPS), which is also a potent IFN inducer, in vitro or in vivo, before being exposed to IFN-gamma was also effective in suppressing the Ia expression. Such suppression was abolished by the addition of anti-IFN-alpha/beta antibodies to the M phi culture along with IFN-gamma. M phi cultured with L-cell conditioned medium (LCM) containing M-CSF were less capable of expressing Ia antigens than those cultured without LCM. The Ia-expressing ability of LCM-treated M phi was also restored by the addition of anti-IFN-alpha/beta antibodies. M phi in the early stage of sterile inflammation were less responsive to IFN-gamma than those in the late stage. These results suggest that endogenous type I IFNs, which are produced in response to natural or synthetic IFN-inducers, regulate M phi Ia expression in an autocrinal manner.

Acute-Phase Reaction↗
PubMed1988

Neuraminidase-treated macrophages stimulate allogenic CD8+ T cells in the presence of exogenous interleukin 2.

Prior work has shown that purified, resident, and inflammatory peritoneal macrophages are weak stimulators of the allogeneic MLR. We have identified conditions whereby thioglycollate-elicited macrophages become stimulatory, but primarily for the CD8+ T cell subset. The conditions were to treat the macrophages with neuraminidase and to supplement the MLR with rIL-2. These treatments together led to proliferative and cytotoxic responses by isolated CD8+ but not CD4+ T cells. Likewise when MHC-congenic strains were evaluated, an MLR was observed across isolated class I but not class II MHC barriers. Pretreatment of the macrophages with IFN-gamma further enhanced expression of class I MHC products and stimulatory activity, but did not seem essential. While these treatments did not render macrophages stimulatory for an MLR in purified CD4+ cells, blastogenesis of CD4+ cells was observed when the MLR involved bulk T cells. Small allogeneic B lymphocytes behaved similarly to macrophages, in the pretreatment with neuraminidase and supplementation with rIL-2 rendered B cells stimulatory for allogeneic, enriched, CD8+, but not CD4+, T cells. Spleen adherent cells, which are mixtures of macrophages and dendritic cells, stimulated both CD4+ and CD8+ T cells, and neither neuraminidase nor exogenous IL-2 was required. We think that these data suggest that most macrophages and small B cells lack three important functions of dendritic cells: a T cell-binding function that can be remedied by neuraminidase treatment, a T cell growth factor-inducing function that can be bypassed with exogenous IL-2, and an IL-2 responsiveness function that is required by CD4+ lymphocytes.

Animals↗
PubMed1988

Effect of recombinant human interferon-alpha A/D on in vivo murine tumor cell growth.

We investigated the effect of human recombinant interferon-alpha A/D A/D-IFN), which is known to delay the growth of murine tumor cells, on the growth of S1 and R1 subline cells of murine Meth A fibrosarcoma in the peritoneal cavity of mice. In vitro growth of S1 cells was sensitive to, and that of R1 cells was resistant to, the direct effect of A/D-IFN, as with murine natural IFN-alpha/beta, which was used originally to isolate these sublines. In vivo, however, the growth of not only S1 cells but also R1 cells was suppressed by the administration of A/D-IFN, and the survival time of tumor-bearing mice was prolonged. Although A/D-IFN had a direct effect on S1 cells in vivo, R1 cells were susceptible only to the indirect effect via the host cells. Macrophages (M phi) harvested from the peritoneal cavity of A/D-IFN-treated mice bearing ascitic R1 cells were very effective in suppressing the in vitro growth of R1 cells; those from non-R1-bearing A/D-IFN-treated mice were less effective. The results of in vitro experiments indicate that M phi are very probably activated by the synergism of A/D-IFN and M phi diameter-activating factor(s) produced by lymphoid cells in tumor-bearing mice.

Animals↗
PubMed1988

Down-regulation of macrophage Ia mRNA expression by interferon (IFN)-alpha and IFN-beta mediated by de novo synthesized protein.

We investigated the regulation of class I and class II major histocompatibility complex (MHC) antigen expression of murine peritoneal macrophages (M phi) by interferons (IFNs) at the mRNA level. Enhancement of class I antigen expression by IFNs (IFN-alpha, beta, and gamma), induction of class II antigen expression by IFN-gamma, and inhibition of class II antigen expression by IFN-alpha or IFN-beta all corresponded to steady-state levels of these MHC-specific mRNAs. Cycloheximide (CHX), a protein synthesis inhibitor, was used to elucidate whether IFN regulation of MHC mRNA expression depends on the newly synthesized proteins. CHX concentration was carefully chosen so that M phi viability was not decreased, total protein synthesis was considerably but not completely inhibited, and suppression of surface class II expression was virtually perfect. Under these conditions CHX did not affect the levels of either class I or class II mRNA, but it prevented IFN-beta from interfering with class II mRNA induction by IFN-gamma. These results indicate that the augmentation of induction and/or accumulation of MHC mRNA by IFNs is not dependent on the de novo synthesis of protein, but the down-regulation of class II mRNA level by IFN-beta is mediated by some newly synthesized protein(s).

Animals↗
PubMed1988

Ontogeny of 'macrophage' function. VI. Down-regulation for Ia-expression of newborn mouse macrophages by endogenous beta-interferon.

Peritoneal exudate macrophages (M phi) of newborn mice (NB-M phi) were apparently almost incapable of expressing Ia antigen even if stimulated by IFN-gamma. No significant difference was observed in the number and the affinity of receptors for IFN-gamma between NB-M phi and M phi of adult mice (Ad-M phi). Addition of indomethacin, a prostaglandin synthesis inhibitor, was ineffective in enhancing the Ia-expression of NB-M phi. Responsiveness of NB-M phi to IFN-gamma, however, was disclosed by the addition to the culture of anti-IFN-beta or anti-IFN-alpha/beta, but not anti-IFN-alpha antibody. Responsiveness of NB-M phi to IFN-gamma was not improved by the depletion of fibroblasts from NB-M phi populations. These results strongly argue that Ia-expression of NB-M phi, which is otherwise to be induced by IFN-gamma, is suppressed by IFN-beta derived from NB-M phi themselves.

Animals↗
PubMed1986

Contrasting effect of alpha/beta- and gamma-interferons on expression of macrophage Ia antigens.

IFN-gamma is known to induce the expression of Ia antigens on macrophages. We found that murine IFN-alpha and -beta blocked the effects of IFN-gamma in a dose-dependent manner. The antagonistic effect of IFN-alpha and -beta was observed even when macrophages were prestimulated with IFN-gamma. These inhibitory effects of IFN-alpha or -beta were blocked by their respective antibodies. The block exerted by IFN-alpha/beta was similar whether Ia levels were monitored by immunofluorescence with anti-Ia mAb, or by stimulation of freshly sensitized, alloreactive T lymphoblasts. Adherent macrophage-rich populations from newborn mice were incapable of expressing Ia antigens following stimulation with IFN-gamma, and would inhibit the response of adult macrophages to this lymphokine. Addition of anti-IFN-beta mAb, but not anti-IFN-alpha allowed newborns' macrophages to express Ia in response to IFN-gamma, and ablated the suppressive activity toward adult cells. These results indicate that IFN-alpha and -beta, which can be produced in the course of self-defense responses and during ontogeny, may contribute to the down-regulation of macrophage Ia expression.

Animals↗