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M Fujino

Publications and source records attributed to M Fujino.

At least 73 records · Page 4Linked to original sources
PubMed1999

Isolation and identification of melanin-concentrating hormone as the endogenous ligand of the SLC-1 receptor.

Melanin-concentrating hormone (MCH), which is an orexigenic peptide, was isolated and identified as the endogenous ligand of the SLC-1 receptor. We established a CHO cell line expressing the rat SLC-1 receptor to search for its endogenous ligand. The extract of rat whole brain showed inhibition of intracellular forskolin-induced cAMP accumulation in rat SLC-1-expressing CHO cells and was purified. Using HPLC purification, we isolated and identified MCH as the endogenous ligand of the SLC-1 receptor. The authentic MCH demonstrated a dose-dependent inhibitory effect on cAMP accumulation in forskolin-stimulated rat and human SLC-1-expressing CHO cells with an EC(50) value of 0.2 nM for both the rat and human SLC-1 receptors. This is the first description of the functional receptor for MCH.

Amino Acid Sequence↗
PubMed1999

Stimulation of prolactin release by prolactin-releasing peptide in rats.

We have previously reported a hypothalamic peptide that shows specific prolactin (PRL)-releasing activity in vitro, named prolactin-releasing peptide (PrRP). However, its activity in vivo has not yet been shown. In this study, we examined whether PrRP could induce specific PRL release in vivo using normal cycling female and male rats. Intravenous injection of PrRP31 increased plasma PRL levels in rats in a dose-dependent manner. PrRP31 (50 nmol/kg i.v.) significantly (P < 0.05) stimulated plasma PRL levels within 25 min after injection in rats in proestrus, estrus, and metestrus. A higher dose of PrRP31 (500 nmol/kg i.v.) was necessary for a significant increase in plasma PRL levels in male rats. These results clearly indicate that female rats, especially at proestrus, are more sensitive to PrRP-induced PRL secretion than male rats. The effect of PrRP on PRL release is affected considerably by the estrous cycle and sex, which suggests that PrRP sensitivity is controlled by the endogenous hormonal milieu, such as estrogen levels. PrRP31 did not affect other pituitary hormone secretions. The results indicate that PrRP shows specific PRL-releasing activity in vivo as well as in vitro and suggest that it plays an important role in the regulation of PRL release under certain physiological conditions.

Adrenocorticotropic Hormone↗
PubMed1999

A small-molecule, nonpeptide CCR5 antagonist with highly potent and selective anti-HIV-1 activity.

The beta-chemokine receptor CCR5 is considered to be an attractive target for inhibition of macrophage-tropic (CCR5-using or R5) HIV-1 replication because individuals having a nonfunctional receptor (a homozygous 32-bp deletion in the CCR5 coding region) are apparently normal but resistant to infection with R5 HIV-1. In this study, we found that TAK-779, a nonpeptide compound with a small molecular weight (Mr 531.13), antagonized the binding of RANTES (regulated on activation, normal T cell expressed and secreted) to CCR5-expressing Chinese hamster ovary cells and blocked CCR5-mediated Ca2+ signaling at nanomolar concentrations. The inhibition of beta-chemokine receptors by TAK-779 appeared to be specific to CCR5 because the compound antagonized CCR2b to a lesser extent but did not affect CCR1, CCR3, or CCR4. Consequently, TAK-779 displayed highly potent and selective inhibition of R5 HIV-1 replication without showing any cytotoxicity to the host cells. The compound inhibited the replication of R5 HIV-1 clinical isolates as well as a laboratory strain at a concentration of 1.6-3.7 nM in peripheral blood mononuclear cells, though it was totally inactive against T-cell line-tropic (CXCR4-using or X4) HIV-1.

Amides↗
PubMed1999

Distribution and characterization of immunoreactive prolactin-releasing peptide (PrRP) in rat tissue and plasma.

We established a sensitive and specific two-site enzyme immunoassay (EIA) for prolactin-releasing peptide (PrRP) using two region-specific monoclonal antibodies. We investigated the tissue distribution and the plasma concentration of immunoreactive (ir-) PrRP in rats using this assay. Ir-PrRP was widely distributed in the central nervous system and pituitary gland. The highest concentration of ir-PrRP was found in the hypothalamus. In peripheral tissues, appreciable levels of ir-PrRP were found only in the adrenal gland. The mean plasma concentration of ir-PrRP was 0.13 +/- 0.01 fmol/ml (mean +/- SEM). In reverse-phase and gel-filtration high performance liquid chromatography, hypothalamic ir-PrRP eluted at a position identical to that of PrRP31 and PrRP20. On the other hand, ir-PrRP from the adrenal gland and plasma eluted only at the position of synthetic PrRP31, indicating that molecular forms of ir-PrRP in vivo differed among tissues.

Adrenal Glands↗
PubMed1999

Cloning and expression of a novel lysophospholipase which structurally resembles lecithin cholesterol acyltransferase.

Lecithin cholesterol acyltransferase (LCAT) is the key enzyme in the esterification of plasma cholesterol and in the reverse cholesterol transport on high-density lipoprotein (HDL). We have found a novel LCAT-related gene among differentially expressed cDNA fragments between two types of foam cells derived from THP-1 cells, which are different in cholesterol efflux ability, using a subtractive PCR technique. The deduced 412-amino-acid sequence has 49% amino acid sequence similarity with human LCAT. In contrast to the liver-specific expression of LCAT, mRNA expression of the gene was observed mainly in peripheral tissues including kidney, placenta, pancreas, testis, spleen, heart, and skeletal muscle. The protein exists in human plasma and is probably associated with HDL. Moreover, we discovered that the recombinant protein hydrolyzed lysophosphatidylcholine (lysoPC), a proatherogenic lipid, to glycerophosphorylcholine and a free fatty acid. We have therefore named this novel enzyme LCAT-like lysophospholipase (LLPL), through which a new catabolic pathway for lysoPC on lipoproteins could be elucidated.

Amino Acid Sequence↗
PubMed1999

Urotensin II is the endogenous ligand of a G-protein-coupled orphan receptor, SENR (GPR14).

Two molecular species of urotensin II (UII) were isolated from porcine spinal cords and identified as the endogenous ligands of a G-protein-coupled orphan receptor, SENR (sensory epithelium neuropeptide-like receptor), which is identical to GPR14. We established a CHO cell line stably expressing the rat SENR and investigated several tissue extracts to evoke the response mediated by the SENR. Extract from porcine spinal cords showed an activity of arachidonic acid metabolites release from SENR-expressing cells and was purified using HPLC. Two active substances were isolated and their sequences were determined as GPTSECFWKYCV and GPPSECFWKYCV, which were revealed to be porcine UII. Synthetic UII peptides caused arachidonic acid metabolites release activity in the rat SENR-expressing cells with an EC(50) value of 1 nM. Three cDNAs encoding the precursor proteins of porcine UII were cloned from a porcine spinal cord cDNA library; 2 consist of 121 amino acid residues and the other, which seemed to be a splicing variant, consist of 85 residues.

Amino Acid Sequence↗
PubMed1999

Treatment of sudden sensorineural hearing loss with a continuous epidural block.

The efficacy of a continuous epidural block was evaluated in the treatment of 20 patients with sudden sensorineural hearing loss (SNHL). Ten patients were treated with continuous cervicothoracic epidural block (group A) and the other 10 were treated with stellate ganglion block (group B). No significant difference in factors affecting prognosis was noted between the groups. In the epidural block group 70% achieved substantial hearing improvement, while this occurred in only 30% of patients undergoing stellate ganglion block. These findings suggest that continuous epidural block can be effective in the treatment of sudden SNHL.

Adult↗
PubMed1999

The quest for novel bioactive peptides utilizing orphan seven-transmembrane-domain receptors.

Various sorts of bioactive molecules including hormones, neurotransmitters, and chemokines transmit signals into cells by binding to so-called seven-transmembrane-domain receptors (7TMRs). The recent progress in cDNA and genome DNA analyses has brought the discovery of numerous genes encoding ligand-unknown "orphan" 7TMRs. We have developed a strategy to identify the ligands of orphan 7TMRs by monitoring specific signal transductions induced in cells expressing orphan 7TMRs. Employing this method, we succeeded in identifying the natural ligands of the orphan 7TMRs, hGR3, and APJ. The ligand peptide identified for hGR3 was found to show a specific prolactin release promoting activity in rat anterior pituitary cells in in vitro culture and was therefore named "prolactin-releasing peptide." We named another novel bioactive peptide "apelin," for "APJ endogenous ligand." Although the biological functions of apelin are still under investigation, APJ reportedly acts as a coreceptor in the process of human immunodeficiency virus infection. We believe that the identification of orphan 7TMR ligands will provide clues to reveal the unknown regulatory mechanisms of various physiological phenomena and opportunities for novel drug discovery in the future.

Animals↗
PubMed1999

Effects of protein kinase inhibitors on radiation-induced WAF1 accumulation in human cultured melanoma cells.

To examine whether protein kinase C (PKC) and A (PKA) contribute to WAF1 induction by ionizing radiation (IR) in cultured human melanomas, the effect of PK inhibitors 1-(5'-isoquinolinesulphonyl)-2-methylpiperazine dihydrochloride (H7), bisindolylmaleimide (GF) and N-[2(p-dromocinnamylamino)ethyl]-5-isoquinolinesulphonamide (H89) on IR-induced WAF1 accumulation was analysed by Western blot analysis. Gamma-ray-induced accumulation of WAF1 showed a peak at 6 Gy in all the cell lines. After gamma-ray irradiation of 6 Gy, a peak of WAF1 accumulation was observed at 6 h in SK-Mel-26, G361 and HM6KO cells, and at 3 h in MeWo cells. In MeWo and SK-Mel-26 cells, the X-ray-induced WAF1 accumulation was decreased by PK inhibitors, GF (PKC inhibitor) or H89 (PKA inhibitor); this did not occur in G361 and HM6KO. In all the cell lines, accumulation of WAF1 induced by X-ray irradiation was suppressed by H7 (PKC and PKA inhibitor). In addition, polymerase chain reaction-single strand conformational polymorphism analysis detected no aberrations in the p53 gene of the four cell lines used. These results suggest that IR-induced WAF1 expression involves PKC and/or PKA activity depending on cell type.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

The Pho85 kinase, a member of the yeast cyclin-dependent kinase (Cdk) family, has a regulation mechanism different from Cdks functioning throughout the cell cycle.

BACKGROUND: The PHO85 gene is a negative regulator of the PHO system in the yeast Saccharomyces cerevisiae and encodes a protein kinase (Pho85p) which is highly homologous to the Cdc28 kinase (Cdc28p). Although the two kinases share a 51% identity and their functional domains are well conserved, PHO85 fails to replace CDC28. Pho85p forms complexes with G1-cyclin homologues, including Pcl1p, Pcl2p and Pcl9p, and is thought to be involved in the cell-cycle regulation at G1 and the end of M. By analysing the genetic and biochemical properties of Pho85p, we studied whether the regulation of Pho85p activity is similar to other cyclin-dependent kinases (Cdks) directly involved in cell cycle regulation. RESULTS: A functional analysis of various Pho85 mutants revealed that E53 in the PSTAIRE sequence was important for Pho85p function. On the other hand, residues in the T-loop including S166, S167 and E168, appeared dispensable for Pho85p function, suggesting that the phosphorylation of S166, corresponding to T161 of Cdc2p and T169 of Cdc28p, was not required for the kinase activity of Pho85p. Instead, we found that phosphorylation of Y18, corresponding to Y15 of Cdc2p and Y19 of Cdc28p, may be important for the binding of Pho80p but not of Pcl1p, suggesting that tyrosine phosphorylation may function as a signal which discriminates various Pho85-cyclins. CONCLUSION: In Cdks functioning throughout the cell cycle, tyrosine phosphorylation is inhibitory to the activation of kinase, whereas the phosphorylation of threonine in the T-loop is essential for activation. Our finding indicates that the regulation mechanism of Pho85p activation appears to be distinct from these Cdks.

Amino Acid Motifs↗
PubMed1999

A case of natural killer/T cell lymphoma of the subcutis resembling subcutaneous panniculitis-like T cell lymphoma.

A case of nasal type natural killer (NK)/T cell lymphoma of the subcutis showing clinical and morphological features that resemble subcutaneous panniculitis-like T cell lymphoma (SPTCL) is presented. A 73-year-old man presented with swelling of the left arm and was diagnosed with panniculitis by a dermatologist. It was concluded from a skin biopsy specimen that the patient had non-Hodgkin's lymphoma of the large cell, NK/T cell type because the neoplastic cells showed polyclonal CD3 immunoreactivity. Treatment with interferon-gamma was initiated, but the patient died of disseminated intravascular coagulation and multiple organ failure 2 months after the initial symptoms appeared. However, involvement of additional organs by the lymphoma was not apparent clinically. An autopsy was not performed. A routinely stained section of the biopsy skin specimen revealed massive necrosis of the subcutaneous fat, karyorrhexis admixed with reactive histiocytes, and large atypical lymphoid cells. Immunoreactivity for polyclonal CD3 was present in the perinuclear region, but absent in the neoplastic cell membranes. CD56, CD45RO (UCHL-1), CD43 (MT1), CD45 (leukocyte common antigen), and the cytotoxic molecules perforin, granzyme B and TIA-1 were positive, but CD20 (L26), CD4, CD8, and betaF1 were negative. Epstein-Barr virus (EBV) mRNA was detected in the nuclei of neoplastic cells by in situ hybridization. Subcutaneous panniculitis-like T cell lymphoma is reported to be an EBV-negative, clonal T cell neoplasm. Although this case showed clinical and morphological features that resembled SPTCL, perinuclear polyclonal CD3 staining and membranous CD56 reactivity seen in neoplastic cells were suggestive of NK cells. Furthermore, the neoplastic cells were positive for EBV. This case is considered to be a NK/T cell lymphoma of the subcutis resembling SPTCL. It is believed that it is important to recognize such a tumor because patients may undergo a fulminant clinical course, despite the tumor being localized in the subcutaneous adipose tissue.

Aged↗
PubMed1999

Immunocytochemical localization of prolactin-releasing peptide in the rat brain.

A hypothalamic peptide that stimulates PRL release has recently been found as a ligand of an orphan receptor and named PRL-releasing peptide (PrRP). PrRP and its receptor were mainly detected in the hypothalamus and pituitary gland, respectively. Its characteristics suggested PrRP to be a novel hypophysiotropic peptide that stimulates the anterior pituitary PRL cell; however, this remained to be confirmed morphologically. We therefore performed an immunocytochemical study to locate PrRP in the rat brain using the region-specific monoclonal antibodies, P2L-1C and P2L-1T, which recognize the C-terminal and the internal sequence of PrRP, respectively. Our results clearly show that dense immunoreactive nerve fiber networks are present in the paraventricular hypothalamic nucleus, supraoptic nucleus, paratenial thalamic nucleus, basolateral amygdaloid nucleus, and bed nucleus of the stria terminalis. A small number of PrRP nerve fibers was also observed in the neural lobe of the hypophysis. However, no immunopositive fiber was observed in the external region of the median eminence, which is known to be the release site of the classical hypophysiotropic hormones. Also, the distribution of PrRP was not changed during the estrous cycle. We therefore concluded that PrRP probably differs from classical hypothalamic releasing hormones. We found the immunoreactive cell bodies to be mainly in the caudal portion of the dorsomedial hypothalamic nucleus and solitary nucleus. A double immunocytochemical procedure revealed that some PrRP-positive neurons showed synaptic contact with oxytocin-positive cell bodies in the paraventricular hypothalamic nucleus, which suggests that PrRP regulates the function of oxytocin neurons. This is the first report to demonstrate the localization of the novel hypothalamic peptide, PrRP, and we therefore suggest that it takes part in a variety of brain functions. However, it is not yet known how PrRP is transported to the pituitary gland, which is the site that contains the greatest concentration of receptors to this new peptide. Therefore, additional work will be required to resolve this discrepancy between ligand and receptor site location.

Animals↗
PubMed1998

Isolation and characterization of a novel endogenous peptide ligand for the human APJ receptor.

In the search for an endogenous ligand of the orphan G protein-coupled receptor APJ, the presence of the ligand in various tissue extracts was examined by measuring the increase in extracellular acidification rate of the cells expressing the APJ receptor as a specific signal induced by the interaction of the receptor and ligand. By monitoring this activity, we isolated an APJ receptor ligand, designated apelin, from bovine stomach extracts. The structures of bovine and human apelin preproproteins were deduced from the sequences of the corresponding cDNAs. The preproproteins consisted of 77 amino acid residues, and the apelin sequence was encoded in the C-terminal regions. Synthetic peptides derived from the C-terminal amino acid sequence of bovine preproapelin were capable of specifically promoting the acidification rate in the cells expressing the APJ receptor in a range from 10(-7) to 10(-10) M, indicating that apelin is an endogenous ligand for the APJ receptor.

Amino Acid Sequence↗
PubMed1998

Expression, purification, and reconstitution of receptor for pituitary adenylate cyclase-activating polypeptide. large-scale purification of a functionally active G protein-coupled receptor produced in Sf9 insect cells.

Human pituitary adenylate cyclase-activating polypeptide (PACAP) receptor was expressed in Sf9 insect cells and Chinese hamster ovary (CHO) cells. The recombinant receptor in Sf9 cell membranes had low affinity for 125I-PACAP27 (Kd = 155.3 pM) and was insensitive to guanosine 5'-O-3-thiotriphosphate (GTPgammaS), whereas the receptor in CHO membranes had a high affinity (Kd = 44.4 pM) and was GTPgammaS sensitive. The receptor in Sf9 membranes was converted to a high affinity state (Kd = 20-40 pM) following solubilization with digitonin. A large quantity (2 mg from 8 liters of insect cells) of the purified PACAP receptors (Bmax = 23.9 nmol/mg of protein) were obtained in a digitonin-induced high affinity state (Kd = 17.3 pM) using biotinylated ligand affinity chromatography. The apparent molecular weight of the purified receptor (Mr = 48,000) was smaller than that of the receptor from CHO cells (Mr = 58,000) due to differences in asparagine-linked sugar chains. The purified receptor reverted to a low affinity state (Kd = 182.6 pM) upon reconstitution into lipid vesicles, however, the receptor reconstituted with Gs protein had a high affinity (Kd = 40.2 pM) and was GTPgammaS sensitive. [35S]GTPgammaS binding to the reconstituted Gs protein was enhanced by PACAP27 and PACAP38 (EC50 = 42.5 and 9.4 pM, respectively) but not by antagonist PACAP(6-38), indicating that the purified receptor was functionally active.

Animals↗