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Biomedical subjects

O Minowa

Publications and source records attributed to O Minowa.

At least 37 records · Page 2Linked to original sources
PubMed1996

Ataxia and epileptic seizures in mice lacking type 1 inositol 1,4,5-trisphosphate receptor.

The inositol 1,4,5-trisphosphate (InsP3) receptor acts as an InsP3-gated Ca2+ release channel in a variety of cell types. Type 1 InsP3 receptor (IP3R1) is the major neuronal member of the IP3R family in the central nervous system, predominantly enriched in cerebellar Purkinje cells but also concentrated in neurons in the hippocampal CA1 region, caudate-putamen, and cerebral cortex. Here we report that most IP3R1-deficient mice generated by gene targeting die in utero, and born animals have severe ataxia and tonic or tonic-clonic seizures and die by the weaning period. An electroencephalogram showed that they suffer from epilepsy, indicating that IP3R1 is essential for proper brain function. However, observation by light microscope of the haematoxylin-eosin staining of the brain and peripheral tissues of IP3R1-deficient mice showed no abnormality, and the unique electrophysiological properties of the cerebellar Purkinje cells of IP3R1-deficient mice were not severely impaired.

Animals↗
PubMed1996

[Applicability of the dual interval echo train (DIET) method for female pelvic diseases].

Dual interval echo train fast SE (DIET-FSE) is a modified fast SE technique. It attenuates fat signals by applying a time interval between an excitation pulse and the first echo, which is the odd-number of the following echo interval, and by decreasing the number of high frequency refocusing pulses before collecting echoes in the center of the k space, which determines the contrast. Unlike many other fat-suppression methods, this technique is less affected by susceptibility effects. In this study, we compared DIET-FSE with FSE and conventional SE of the female pelvis. The results of DIET-FSE showed a stable, obvious fat suppression effect which resulted in the easy detection of pelvic organs such as the intestines and ovaries, as compared with FSE. The reductions in imaging time and motion artifacts also permitted more precise differentiation between the normal pelvic organs and lesions than conventional T2-weighted SE. These results imply that the DIET-FSE is useful for the diagnosis of female pelvic disorders.

Female↗
PubMed1995

Placental defect and embryonic lethality in mice lacking hepatocyte growth factor/scatter factor.

Hepatocyte growth factor/scatter factor (HGF/SF) functions as a mitogen, motogen and morphogen for a variety of cultured cells. The genes for HGF/SF and its receptor (the c-met proto-oncogene product) are expressed in many tissues during the embryonic periods and in the adult. HGF/SF is thought to mediate a signal exchange between the mesenchyme and epithelia during mouse development. To examine the physiological role of HGF/SF, we generated mutant mice with a targeted disruption of the HGF/SF gene. Here we report that homozygous mutant embryos have severely impaired placentas with markedly reduced numbers of labyrinthine trophoblast cells, and die before birth. The growth of trophoblast cells was stimulated by HGF/SF in vitro, and the HGF/SF activity was released by allantois in primary culture of normal but not mutant embryos. These findings suggest that HGF/SF is an essential mediator of allantoic mesenchyme-trophoblastic epithelia interaction required for placental organogenesis.

Allantois↗
PubMed1994

Excitation-contraction uncoupling and muscular degeneration in mice lacking functional skeletal muscle ryanodine-receptor gene.

Contraction of skeletal muscle is triggered by the release of Ca2+ from the sarcoplasmic reticulum (SR) after depolarization of transverse tubules. The ryanodine receptor exists as a 'foot' protein in the junctional gap between the sarcoplasmic reticulum and the transverse tubule in skeletal muscle, and is proposed to function as a calcium-release channel during excitation-contraction (E-C) coupling. Previous complementary DNA-cloning studies have defined three distinct subtypes of the ryanodine receptor in mammalian tissues, namely skeletal muscle, cardiac and brain types. We report here mice with a targeted mutation in the skeletal muscle ryanodine receptor gene. Mice homozygous for the mutation die perinatally with gross abnormalities of the skeletal muscle. The contractile response to electrical stimulation under physiological conditions is totally abolished in the mutant muscle, although ryanodine receptors other than the skeletal-muscle type seem to exist because the response to caffeine is retained. Our results show that the skeletal muscle ryanodine receptor is essential for both muscular maturation and E-C coupling, and also imply that the function of the skeletal muscle ryanodine receptor during E-C coupling cannot be substituted by other subtypes of the receptor.

Animals↗
PubMed1993

Binding and transcriptional activation of the promoter for the neural cell adhesion molecule by HoxC6 (Hox-3.3).

Scores of homeobox gene-encoded transcription factors are expressed in a definite spatiotemporal pattern during embryogenesis and regulate a series of as yet unidentified target genes to help coordinate the morphogenetic process. We have suggested that homeobox gene products modulate the expression of adhesion molecule genes and have shown in cotransfection experiments that the promoters for the neural cell adhesion molecule (N-CAM) and cytotactin/tenascin genes respond to cues from different homeobox-containing genes. In this study, we show that the HoxC6 (Hox-3.3)-encoded homeoprotein binds to a DNA sequence in the N-CAM promoter CCTAATTATTAA, designated homeodomain binding site I (HBS-I). To test whether HoxC6 regulated N-CAM promoter activity, we cotransfected the Long and Short reading frame variants of Xenopus HoxC6 (CMV-HoxC6-L and CMV-HoxC6-S) driven by the human cytomegalovirus (CMV) promoter together with a chloramphenicol acetyltransferase (CAT) reporter gene driven by the mouse N-CAM promoter (N-CAM-Pro-CAT). Cotransfection of NIH 3T3 cells with either of the CMV-HoxC6 expression vectors stimulated N-CAM promoter-driven CAT expression. A 47-bp region from the N-CAM promoter that included HBS-I and an adjacent potential HBS, HBS-II, conferred HoxC6 regulation on a simian virus 40 minimal promoter. HBS-I was sufficient for transactivation of the minimal promoter by CMV-HoxC6-S. However, transcriptional activation by CMV-HoxC6-L required both HBS-I and HBS-II, inasmuch as mutation of either HBS-I, HBS-II, or both motifs abolished the response. These studies suggest that HBS-I is a target site for binding and transcriptional control of the N-CAM promoter by homeoproteins, although accessory DNA sequences (such as HBS-II) may also be required. Together with previous studies, these results support the notion that N-CAM gene expression may be controlled by different combinations of homeoproteins that appear in a place-dependent manner during embryogenesis.

3T3 Cells↗
PubMed1991

The primary structure of two molecular species of porcine organ-common type acylphosphatase.

Electrophoretically homogeneous preparations of organ-common type acylphosphatase from porcine testis and brain were separated into two molecular species by reversed-phase liquid chromatography. From tryptic peptide map analysis, it was inferred that each of the two testis proteins is the same as the corresponding one of the two brain proteins. The complete primary structures of the two acylphosphatases from testis were then determined. The one molecular species consists of 100 amino acid residues: [sequence; see text] The other consists of 98 amino acid residues identical to the 3rd-100th residues of the above sequence and is also acetylated at the amino-terminal alanine. The 98-residue sequence has only 59% homology with porcine muscle acylphosphatase, but has 92% homology with human erythrocyte acylphosphatase. It was thus confirmed that the major acylphosphatases in testis, brain, and erythrocyte belong to the same organ-common type isoenzyme, distinct from the muscle type isoenzyme.

Acid Anhydride Hydrolases↗
PubMed1990

Functional expression of microsomal and mitochondrial cytochrome P-450 (d and SCC) in COS-7 cells from cloned cDNA.

Using full length cDNA introduced into COS-7 cells, two species of P-450 with entirely different physiological functions have been expressed in enzymatically active form. One is P-450d, which is known to reside in the microsomes of rat hepatocytes where it acts as a drug-metabolizing enzyme; the other is P-450(SCC), which catalyzes the conversion of cholesterol to pregnenolone in the rate-limiting reaction of steroidogenesis in mitochondria of adrenal cortex cells. Northern blot and immunoblot analyses revealed that the mRNA and protein of these P-450 species were efficiently produced in COS-7 cells. The protein contents amounted to nearly 0.1% of the total cell protein as estimated from immunoblotting and low temperature CO difference spectra. The subcellular localization of the products indicated that they were correctly sorted to the microsomes and mitochondria, respectively. We have succeeded in eliciting most of the activity of the expressed microsomal P-450d by reconstruction with NADPH-cytochrome P-450 reductase, while the optimal conditions for the mitochondrial enzyme in the COS cells remain to be studied. These results show the applicability of the COS-7 expression system to investigations of the functions of members of the P-450 superfamily whose cDNA has been newly isolated.

Animals↗
PubMed1989

Isolation and characterization of C-reactive protein and serum amyloid P component from bovine serum.

C-reactive protein (CRP) and serum amyloid P component (SAP), which are known as acute phase reactants in human and many other animals, were purified from cow sera. Affinity chromatography using HE agarose gel was the most effective method to isolate both CRP and SAP from a large volume of bovine serum. Separation of CRP and SAP from the mixed preparation could be performed by DEAE-cellulose column chromatography, gel permeation HPLC using TSK-G3000SW or affinity chromatography using phosphorylcholine derivatives of bovine serum albumin-conjugated Toyopearl HW 65. Bovine CRP and SAP were identified as genuine CRP- and SAP-class proteins by their cross reactivities with anti-human CRP and anti-human SAP, respectively, and by their homology in amino acid compositions compared with those of human CRP and SAP, respectively. Bovine CRP moved slower than beta-globulin, and bovine SAP moved in the beta-globulin region in agarose gel electrophoresis. Both of them gave single bands in native polyacrylamide gel electrophoresis (PAGE). Bovine CRP and SAP molecular weights were estimated to be 100,600 and 109,500 daltons respectively, by sedimentation equilibrium analysis. Bovine CRP showed 23K dalton subunits by sodium laurylsulfate-PAGE and bovine SAP showed 28K and 32K dalton subunits, both of which were glycosylated and had identical amino acid compositions, indicating that both CRP and SAP molecules are pentamers. In fact, they appeared to have pentameric disk-like configurations in electronmicroscopical examination.

Amino Acids↗
PubMed1988

Purification and characterization of alpha 1-thiol proteinase inhibitor and its identity with kinin- and fragment 1.2-free high molecular weight kininogen.

1. alpha 1-Thiol proteinase inhibitor (alpha 1 TPI) purified from outdated human plasma was a glycoprotein with Mr 83,000 and was composed of heavy and light chains held together with a disulfide bond. 2. The data on amino acid composition, amino terminal sequence of the light chain and carboxyl terminal sequences of the heavy and light chains indicate that alpha 1 TPI is identical with kinin- and fragment 1.2-free HMW kininogen. 3. Purified human plasmin generated a derivative having the same molecular weight (Mr 83,000), same subunit structure (heavy and light chains) and same inhibitory capacity as alpha 1 TPI from HMW kininogen and kinin-free HMW kininogen. This indicated the possibility that alpha 1 TPI is derived from HMW kininogen by plasmin.

Amino Acids↗
PubMed1988

Calmodulin fragments can not activate target enzymes.

Under conditions where nM level of calmodulin was able to show full activation of myosin light chain kinase and cyclic-nucleotide phosphodiesterase, the fragments of calmodulin at concentrations as high as 20 microM failed to activate these enzymes in the presence of Ca2+. The fragments tested were Ala1-Lys75 (F12), Ala1-Arg74 (F12'), Lys75-Lys148 (F34'), Met76-Lys148 (F34'), Asp78-Lys148 (F34), Ala1-Arg106 (F123), and His107-Lys148 (F4). Purification of the proteolytic fragments through HPLC was necessary to remove contaminant calmodulin. Among the fragments, that corresponding to the C-terminal half domain inhibited myosin light chain kinase activity with the inhibition constant of 13 microM. The integrated structure of calmodulin consisting of N-terminal half domain, C-terminal half domain, and the linker peptide was indispensable for the enzyme activation. We discuss the functions of the two structural domains (N-domain and C-domain) in the activation of various enzymes.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1987

The primary structure of chicken muscle acylphosphatase isozyme Ch1.

The amino acid sequence of chicken muscle acylphosphatase isozyme Ch1 was determined. The protein consists of 102 amino acid residues, does not contain histidine, and the NH2-terminus is acetylated: Ac-Ser-Ala-Leu-Thr-Lys-Ala-Ser-Gly-Ser- Leu-Lys-Ser-Val-Asp-Tyr-Glu-Val-Phe-Gly-Arg-Val-Gln-Gly-Val-Cys-Phe-Arg- Met- Tyr-Thr-Glu-Glu-Glu-Ala-Arg-Lys-Leu-Gly-Val-Val-Gly-Trp-Val-Lys-Asn- Thr- Ser-Gln-Gly-Thr-Val-Thr-Gly-Gln-Val-Gln-Gly-Pro-Glu-Asp-Lys-Val-Asn-Ala- Met- Lys-Ser-Trp-Leu-Ser-Lys-Val-Gly-Ser-Pro-Ser-Ser-Arg-Ile-Asp-Arg-Thr-Lys- Phe-Ser- Asn-Glu-Lys-Glu-Ile-Ser-Lys-Leu-Asp-Phe-Ser-Gly-Phe-Ser-Thr-Arg-Tyr-OH. This sequence differs in 44% of the total positions from the other isozyme (Ch2) of chicken muscle acylphosphatase (Ohba et al., the accompanying paper). The sequence of Ch1 has three substitutions from that of turkey muscle acylphosphatase; these are Ser from Ala at position 9, Ser from Arg at 47, and Lys from Asn at 83. The sequence has about 80% homology with those mammalian muscle acylphosphatases.

Acid Anhydride Hydrolases↗
PubMed1987

The primary structure of chicken muscle acylphosphatase isozyme Ch2.

The amino acid sequence of one, Ch2, of the two isozymes of chicken muscle acylphosphatase was determined. It consists of 98 amino acid residues with N-acetylalanine at the amino(N)-terminus and contains no cysteine: Ac-Ala-Gly-Ser-Glu- Gly-Leu-Met-Ser-Val-Asp-Tyr-Glu-Val-Ser-Gly-Arg-Val-Gln-Gly-Val-Phe-Phe- Arg- Lys-Tyr-Thr-Gln-Ser-Glu-Ala-Lys-Arg-Leu-Gly-Leu-Val-Gly-Trp-Val-Arg-Asn- Thr- Ser-His-Gly-Thr-Val-Gln-Gly-Gln-Ala-Gln-Gly-Pro-Ala-Ala-Arg-Val-Arg-Glu- Leu- Gln-Glu-Trp-Leu-Arg-Lys-Ile-Gly-Ser-Pro-Gln-Ser-Arg-Ile-Ser-Arg-Ala-Glu- Phe- Thr-Asn-Glu-Lys-Glu-Ile-Ala-Ala-Leu-Glu-His-Thr-Asp-Phe-Gln-Ile-Arg-Lys- COOH. The sequence differs in 44% of the total positions from the other isozyme, Ch1. Comparison of the sequence and the predicted conformational profile of Ch2 with those of Ch1 suggests that they share a common evolutionary origin and appear to have retained similar conformations throughout their evolutionary development.

Acid Anhydride Hydrolases↗
PubMed1987

Isozymes of isocitrate dehydrogenase from an obligately psychrophilic bacterium, Vibrio sp. strain ABE-1: purification, and modulation of activities by growth conditions.

Each of the two isozymes, which are different in thermostability and quaternary structure, of isocitrate dehydrogenase (NADP+) [IDH: EC 1.1.1.42] was purified to an electrophoretically homogeneous state from an obligately psychrophilic marine bacterium, Vibrio sp. strain ABE-1. Hydrophobic chromatography was an efficient procedure to separate the two isozymes from each other. The isoelectric points of isozyme I (IDH-I; a dimer, Mr 88,100) and isozyme II (IDH-II; a monomer, Mr 80,500) were found to be pH 4.9 and 5.2, respectively. The two isozymes were similar in amino acid compositions, though there were slight differences in the contents of nonpolar and hydroxyl amino acids. However, their NH2-terminal amino acid sequences and immunochemical properties were clearly different from each other. The NH2-terminal amino acid sequence analysis also indicated that the subunits of IDH-I are chemically identical or highly homologous. Non-immuno-crossreactivity between the isozymes enabled us to measure the intracellular contents of the isozymes. IDH-I and -II were found to be differentially regulated in vivo by various growth conditions. IDH-I was induced by acetate, while IDH-II remained almost unchanged.

Acetates↗
PubMed1985

Hydrogen bonding in the carboxyl-terminal half-fragment 78-148 of calmodulin as studied by two-dimensional nuclear magnetic resonance.

The C-terminal half-fragment (residues 78-148) of scallop testis calmodulin was investigated by 500-MHz two-dimensional proton NMR in order to clarify the structure and the structural change accompanying Ca2+ binding. The sequential resonance assignment to individual amino acid residues was made in part (27 out of 71 residues) by a combination of correlated spectroscopy and nuclear Overhauser effect spectroscopy of a 90% H2O solution. In the Ca2+-bound state, resonances of backbone amide protons of Gly-98, Gly-134, Ile-100, Asn-137, and Val-136 appear at extremely low fields. These findings suggest that amide protons of these residues are hydrogen bonded. In the Ca2+-free state, the amide resonances of Ile-100 and Gly-134 disappear into the crowded normal shift region. This observation indicates that two hydrogen bonds of Ile-100 and Gly-134 are destroyed (or weakened) as Ca2+ ions are removed from two Ca2+-binding sites. Chemical shifts of amide and alpha-protons of residues located in the Ca2+-binding loop of domain III are similar to those of domain IV. These results suggest that the conformations of the two loops are very similar. The present results can be interpreted in terms of a structure predicted by Kretsinger [Kretsinger, R.H. (1980) Ann. N.Y. Acad. Sci. 356, 14].

Amino Acid Sequence↗
PubMed1985

Calcium binding and conformation of regulatory light chains of smooth muscle myosin of scallop.

Calcium binding was studied with two regulatory light chains (RLC-a and RLC-b) of smooth muscle myosin of scallop. With the equilibrium dialysis method, the binding of 0.98 mol Ca2+ per mol of RLC-b was observed with a dissociation constant of 2.3 X 10(-5) M. Similar values for RLC-b, 1.9 X 10(-5) M, and RLC-a, 1.5 X 10(-5) M, were obtained by measuring the difference absorption spectrum induced by Ca2+. The difference molar absorption coefficient at 288 nm was 159 and 209 M-1 X cm-1 for RLC-a and RLC-b, respectively, while it was -34 M-1 X cm-1 for the regulatory light chain of striated muscle myosin of scallop (RLC-st). Proton NMR spectra of the three light chains were very similar to each other and were broader than those of other Ca2+ binding proteins, parvalbumin and calmodulin. The regulatory light chains may be more rigid than in these Ca2+ binding proteins. CD spectra were measured for the three light chains, and the estimated helix contents were 27, 29, and 24%, respectively, for RLC-a, RLC-b, and RLC-st. All these results in comparison with the primary structures led us to suppose that the polypeptide of regulatory light chains is folded in such a way that domain 4 becomes near to the calcium binding site of domain 1. The decrease in intact light chains on trypsin digestion was determined for the gel electrophoretic patterns. RLC-a was 6 times more susceptible to the tryptic digestion than RLC-b.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗