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M Iwami

Publications and source records attributed to M Iwami.

At least 37 records · Page 2Linked to original sources
PubMed1997

Novel subtype-selective nonpeptide bradykinin receptor antagonists FR167344 and FR173657.

We describe the receptor binding and antagonistic properties of two novel nonpeptide antagonists, FR167344 (3-bromo-8-[2,6-dichloro-3-[N-[(E)-4-(N,N-dimethylcarbamoyl)cinnamido acetyl]-N-methylamino]benzyloxy]-2-methylimidazo[1,2-a]pyridine hydrochloride) and FR173657 (8-[3-[N-[(E)-3-(6-acetamidopyridin-3-yl)acryloylglycyl]-N-m ethylamino]-2,6-dichlorobenzyloxy]-2-methylquinoline), for the human bradykinin receptor subtypes (B1 and B2). In competitive experiments using membranes prepared from Chinese hamster ovary cells expressing the bradykinin receptor subtypes, FR167344 and FR173657 showed a high affinity binding to the B2 receptor with IC50 values of 65 and 8.9 nM, respectively, and no binding affinity for the B1 receptor. FR167344 and FR173657 inhibited the B2 receptor-mediated phosphatidylinositol (PI) hydrolysis and produced a concentration-dependent rightward shift in the dose-response curve to bradykinin. This shift was accompanied by a progressive reduction of maximal response. Estimated pA2 values for the antagonism of bradykinin-induced PI hydrolysis by FR167344 and FR173657 were 8.0 and 9.0, respectively. FR167344 and FR173657 showed no stimulatory effects on PI hydrolysis. Therefore, FR167344 and FR173657 are potent, highly selective, and insurmountable antagonists for the human bradykinin B2 receptor.

Animals↗
PubMed1997

Bombyxin F1 gene: structure and expression of a new bombyxin family gene that forms a pair with bombyxin B10 gene.

Bombyxin F1 gene, a new bombyxin family gene, has been identified. The F1 gene forms a pair with bombyxin B10 gene with an opposite transcriptional orientation and the gene pair F1/B10 is located between bombyxin gene pairs B9/C1 and A7/B7 in a bombyxin gene cluster. The nucleotide sequence of the F1 gene and its deduced amino acid sequence deviate moderately from those characterized previously for the family-A, family-B, family-C, family-D, and family-E bombyxin genes; the bombyxin F1 gene and preprobombyxin F1 share no more than 62% and 53% sequence identities with other bombyxin members, respectively. Harr-plot analysis indicated that the spacer of the F1/B10 gene pair has low sequence similarity with that of other bombyxin gene pairs characterized. The bombyxin F1 mRNA in Bombyx mori brain was shown to locate in four pairs of medial neurosecretory cells, which also produce other bombyxin family mRNAs. Genomic Southern hybridization indicated that the Bombyx haploid genome contains a single copy of the family-F bombyxin gene.

Amino Acid Sequence↗
PubMed1996

Bombyxin gene expression in tissues other than brain detected by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization.

Bombyxin is a 5 kDa insulin-related peptide produced in four pairs of medial neurosecretory cells in the brain of the silkmoth Bombyx mori. We demonstrate here the presence of bombyxin mRNA in tissues other than brain: ganglia, epidermis, testis, ovary, fat body, silk gland, Malpighian tubule, midgut, and hindgut of the Bombyx fifth instar larvae. Bombyxin mRNA was detected by Oligotex reverse transcription-polymerase chain reaction (RT-PCR), a rapid and simple procedure of reverse transcription-PCR, and in situ hybridization. The Oligotex RT-PCR method effectively eliminated the contaminating DNA in RNA samples and amplified bombyxin mRNA efficiently. In situ hybridization of the Bombyx ovary clearly demonstrated the localization of the bombyxin mRNA in the ovariole. The present study is the first demonstration of expression of brain neurosecretory peptide in tissues other than the central nervous system in insects at RNA level.

Animals↗
PubMed1996

Multiple gene copies for bombyxin, an insulin-related peptide of the silkmoth Bombyx mori: structural signs for gene rearrangement and duplication responsible for generation of multiple molecular forms of bombyxin.

Thirty-eight genes that encode bombyxin, the insulin-related brain secretory peptide of the silkmoth Bombyx mori, have been cloned and characterized. These genes have been classified into four families, A, B, C and D, according to their sequence similarity. All the bombyxin genes lack introns. Five of them have structural features of pseudogenes. The 38 genes cluster in the three DNA segments of Bombyx in unique distribution patterns. Their arrangement has been classified into three categories: gene pairs, gene triplets and single genes. In the pairs, two bombyxin genes belonging to families B and A (B/A) or to families B and C (B/C) are apposed with opposite transcriptional orientation. All triplets are arranged in the order of the family-B, family-C and family-A genes, and the transcriptional directions of the family-C and family-A genes are opposite to the direction of the family-B gene. The bombyxin gene triplets may have been generated by an unequal crossing-over between two gene pairs, B/A and B/C. Crossing-over may have occurred in the bombyxin family-B genes to increase their structural diversity. Duplications may have served to multiply the bombyxin gene triplets. These genomic rearrangements are thought to have led to the generation of multiple bombyxin gene copies and their diversity in structure and genomic organization.

Amino Acid Sequence↗
PubMed1996

Bombyxin-related peptides: cDNA structure and expression in the brain of the hornworm Agrius convolvuli [corrected].

We have cloned three cDNAs from the sweet potato hornworm Agrius convolvuli that encode precursor molecules for peptides structurally related to bombyxin, an insulin-related brain secretory peptide in Bombyx mori. The Agrius bombyxin-related peptide (ABRP) cDNAs are classified into type A and B according to their sequence similarity. The prepro-ABRPs deduced from the cDNA sequences have the insulin-like domain organization of signal peptide/B chain/C peptide/A chain. The ABRP transcripts in Agrius brain were shown to locate in four pairs of medial neurosecretory cells, the homologous group of neurosecretory cells that produce bombyxins in Bombyx brain. Genomic Southern analysis indicated the presence of multiple copies of ABRP gene in the Agrius genome. Results showed that the ABRP genes are remarkably different from the vertebrate insulin genes in the number of copy and spatial localization of the transcripts.

Amino Acid Sequence↗
PubMed1995

Insect prothoracicotropic hormone: a new member of the vertebrate growth factor superfamily.

Prothoracicotropic hormone (PTTH) is a brain neurosecretory protein that controls insect development. PTTH of the silkmoth Bombyx mori is a homodimeric protein, the subunit of which consists of 109 amino acids. Clear-cut sequence similarity to any other proteins has not been observed. By disulfide-bond pattern analysis and modeling of the PTTH structure based on the known three-dimensional (3D) structures of growth factor family with cystine-knot motif, we propose that the PTTH protomer adopts the fold unique to the structural superfamily of the growth factors, beta-nerve growth factor (beta-NGF), transforming growth factor-beta 2 (TGF-beta 2), and platelet-derived growth factor-BB (PDGF-BB). The insect neurohormone PTTH appears to be a member of the growth factor superfamily, sharing a common ancestral gene with the three vertebrate growth factors, beta-NGF, TGF-beta 2 and PDGF-BB.

Amino Acid Sequence↗
PubMed1995

Human calgizzarin; one colorectal cancer-related gene selected by a large scale random cDNA sequencing and northern blot analysis.

A cDNA library was constructed from COLO 205 and 1056 clones randomly selected from this library were partially sequenced. Two hundred and two (38.4%) out of 526 independent genes had more than 80% similarity to the genes reported in GenBank. In Northern blot analysis, 96 out of 98 genes were shown to be expressed at the same level in colon and lung carcinoma cell lines and control fibroblasts. Only two clones, including human synovial phospholipase A-2 and a homologue to rabbit calgizzarin, were expressed at different levels among these cell lines. The full sequence of human calgizzarin was determined and its expression was remarkably elevated in colorectal cancers compared with that in normal colorectal mucosa.

Amino Acid Sequence↗
PubMed1994

Subtype- and species-selectivity of a tachykinin receptor antagonist, FK888, for cloned rat and human tachykinin receptors.

We investigated the receptor-binding properties and potencies of FK888 (N2-[(4R)-4-hydroxy-1-(1-methyl-1H-indol-3-yl)carbonyl-L-prolyl]-N- phenylmethyl-3-(2-naphthyl)-L-alaninamide), a tachykinin receptor antagonist, for the rat and human tachykinin receptor subtypes (NK1, NK2 and NK3) expressed in transfected mammalian cells. In displacement analyses, using membrane preparations derived from monkey kidney COS-7 cells transiently expressing tachykinin receptor subtypes, FK888 showed a subtype selectivity for NK1 receptor and its affinity for the human NK1 receptor was 320-fold higher than that for the rat NK1 receptor, demonstrating species difference in its binding affinity. This was in marked contrast to FK224 (N-[N2-[N-[N-[N-[2,3-didehydro-N-methyl-N-[N-[3-(2-pentylphenyl )- propionyl]-L-threonyl]tyrosyl-L-leucynyl]-D-phenylalanyl]-L- allothreonyl]-L-asparaginyl]-L-serine-n-lactone) that was selective for NK1 and NK2 receptors with similar affinities for the rat and human receptors. In Chinese hamster ovary cells permanently expressing the human NK1 receptor, FK888 inhibited the substance P-induced phosphatidylinositol hydrolysis and produced a parallel shift in the dose-response curve for substance P. Schild analysis of the antagonism of phosphatidylinositol hydrolysis by FK888 yielded a pA2 value of 8.9 and a slope of 0.97 of the regression line. FK888 itself showed no stimulatory effect on phosphatidylinositol hydrolysis in Chinese hamster ovary cells expressing the human NK1 receptor. Thus, FK888 is a potent, competitive and selective antagonist for human NK1 receptor.

Animals↗
PubMed1994

Structure and expression of the gene for the prothoracicotropic hormone of the silkmoth Bombyx mori.

We cloned and characterized two allelic variants of the gene for the Bombyx mori prothoracicotropic hormone (PTTH), a homodimeric 30-kDa brain secretory protein. These PTTH genes contain five exons that encode a precursor protein consisting of 224 amino acid residues whose C-terminal 109 residues represent the PTTH subunit. The Bombyx haploid genome contains a single copy of the PTTH gene. The major site of PTTH expression is the brain but expression at a very low level occurs in the gut. One Bombyx brain at day 0 of the fifth larval instar contained 2.4-2.8 pg PTTH mRNA, and this amount did not change markedly during larval-pupal development.

Amino Acid Sequence↗
PubMed1993

Immunogenicity of Vibrio cholerae O1 fimbriae in animal and human cholera.

Parenteral immunization with either formalin-fixed whole cells of the fimbriate Bgd17 strain or purified fimbriae protected against Vibrio cholerae O1 infection in rabbits, independent of biotype and serotype. Parenteral immunization of adult rabbits with purified fimbriae prior to V. cholerae O1 challenge resulted in a reduction of 2 to 3 orders of magnitude in the number of bacteria recovered from the small intestines of immunized rabbits in comparison to non-immunized controls. IgG and IgA antibodies against fimbrillin of V. cholerae O1 were detected in the convalescent sera of patients with cholera; however, little fimbrial antigen was detected in the commercially available cholera vaccines when examined by polyclonal and monoclonal antibodies against fimbriae. These data suggest that fimbrial hemagglutinin is a major adhesin of V. cholerae O1 and that parenteral immunization with fimbriae generates a specific immune response in the gut that may serve as one means of mitigating subsequent V. cholerae O1 gut infection.

Animals↗
PubMed1992

Structure and expression of bombyxin-related peptide genes of the moth Samia cynthia ricini.

From the genomic DNA of the moth Samia cynthia ricini, we cloned and characterized six clustered genes that encode precursor molecules for peptides structurally related to bombyxin, a Bombyx mori brain secretory peptide that is structurally like insulin and functionally like the prothoracicotropic hormone. The precursor molecules deduced from these genes have the domain organization of signal peptide/B-chain/C-peptide/A-chain, as in preprobombyxins and preproinsulins. The Samia bombyxin-related peptide (SBRP) genes are classified into families A and B according to their sequence homology. Two genes belonging to different families are arranged close to each other to form a pair with opposite transcriptional orientations (A-1/B-1, A-2/B-2, and A-3/B-3). None of these genes have introns, and gene B-3 has an in-frame stop codon representing a pseudogene. Four genes, A-1, A-3, B-1, and B-2, are expressed in Samia brain. Genomic Southern hybridization suggests that the Samia genome contains many other SBRP genes.

Amino Acid Sequence↗
PubMed1992

Biphenomycin A production by a mixed culture.

Production of biphenomycin A by Streptomyces griseorubiginosus 43708 was stimulated by a mixed culture with a partner strain, Pseudomonas maltophilia 1928. This stimulatory effect on biphenomycin A accumulation by the mixed culture was caused by the enzyme activity which strain 1928 possessed. It is suggested that in a mixed culture strain 43708 produces a precursor of biphenomycin A in culture broth and that strain 1928 converts the precursor to biphenomycin A.

Anti-Bacterial Agents↗
PubMed1991

Construction of a 7-aminocephalosporanic acid (7ACA) biosynthetic operon and direct production of 7ACA in Acremonium chrysogenum.

We have used cDNA encoding D-amino acid oxidase, and genomic DNA encoding cephalosporin acylase from Fusarium solani and Pseudomonas diminuta, respectively, to construct a novel hybrid 7-aminocephalosporanic acid (7ACA) biosynthetic operon under the control of regulatory elements from the alkaline protease gene of Acremonium chrysogenum. Transformants of A. chrysogenum BC2116, a high cephalosporin-producing strain, containing this operon, synthesized and secreted low levels of 7ACA. Although the amounts are not yet commercially significant, this represents the first microbial production of 7ACA and demonstrates the feasibility of introducing new biosynthetic capabilities into industrial microorganisms by combining fungal and bacterial genes.

Acremonium↗
PubMed1991

Cloning and nucleotide sequencing of a novel 7 beta-(4-carboxybutanamido)cephalosporanic acid acylase gene of Bacillus laterosporus and its expression in Escherichia coli and Bacillus subtilis.

A strain of Bacillus species which produced an enzyme named glutaryl 7-ACA acylase which converts 7 beta-(4-carboxybutanamido)cephalosporanic acid (glutaryl 7-ACA) to 7-amino cephalosporanic acid (7-ACA) was isolated from soil. The gene for the glutaryl 7-ACA acylase was cloned with pHSG298 in Escherichia coli JM109, and the nucleotide sequence was determined by the M13 dideoxy chain termination method. The DNA sequence revealed only one large open reading frame composed of 1,902 bp corresponding to 634 amino acid residues. The deduced amino acid sequence contained a potential signal sequence in its amino-terminal region. Expression of the gene for glutaryl 7-ACA acylase was performed in both E. coli and Bacillus subtilis. The enzyme preparations purified from either recombinant strain of E. coli or B. subtilis were shown to be identical with each other as regards the profile of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were composed of a single peptide with the molecular size of 70 kDa. Determination of the amino-terminal sequence of the two enzyme preparations revealed that both amino-terminal sequences (the first nine amino acids) were identical and completely coincided with residues 28 to 36 of the open reading frame. Extracellular excretion of the enzyme was observed in a recombinant strain of B. subtilis.

Amidohydrolases↗
PubMed1990

Molecular cloning of the Bombyx mori prothoracicotropic hormone.

Prothoracicotropic hormone (PTTH), a brain secretory polypeptide of insects, stimulates the prothoracic glands to produce and release ecdysone, the steroid essential to insect development. The complementary DNAs encoding PTTH of the silkmoth Bombyx mori were cloned and characterized, and the complete amino acid sequence was deduced. The data indicated that PTTH is first synthesized as a 224-amino acid polypeptide precursor containing three proteolytic cleavage signals. The carboxyl-terminal component (109 amino acids) that follows the last cleavage signal represents one PTTH subunit. Two PTTH subunits are linked together by disulfide bonds, before or after cleavage from prepro-PTTH, to form a homodimeric PTTH. When introduced into Escherichia coli cells, the complementary DNA directed the expression of an active substance that was functionally indistinguishable from natural PTTH. In situ hybridization showed the localization of the prepro-PTTH mRNA to two dorsolateral neurosecretory cells of the Bombyx brain.

Amino Acid Sequence↗
PubMed1989

cDNA structure and expression of bombyxin, an insulin-like brain secretory peptide of the silkmoth Bombyx mori.

Bombyxin, previously referred to as 4K-prothoracicotropic hormone, is a brain peptide of the silkmoth Bombyx mori, the amino acid sequence of which shows considerable homology with vertebrate insulin family peptides. Two independent clones have been isolated from a Bombyx larval brain cDNA library by using a synthetic oligonucleotide probe, one with the complete coding region for preprobombyxin (lambda Bb360) and the other covering the coding region, possibly for bombyxin, only partially (lambda Bb204). lambda Bb360 encodes preprobombyxin in the order of prepeptide/B-chain/proteolytic cleavage signal/C-peptide/proteolytic cleavage signal/A-chain. This domain organization of preprobombyxin is the same as that of preproinsulins, suggesting that the tertiary structure and posttranslational modification mechanism are conserved through the evolution of bombyxin and insulin. Genomic Southern hybridization analyses using this cDNA as probe suggest that the Bombyx genome contains multiple copies of bombyxin gene. Northern hybridization analyses indicate that the concentration of lambda Bb360-type bombyxin mRNA in the bombyxin-producing cells is remarkably high (2.8 x 10(9) molecules/micrograms of total RNA), without undergoing appreciable change during larval-pupal development.

Amino Acid Sequence↗