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Biomedical subjects

I Matsuda

Publications and source records attributed to I Matsuda.

At least 181 records · Page 10Linked to original sources
PubMed1993

LDL inhibits the mediation of cholesterol efflux from macrophage foam cells by apoA-I-containing lipoproteins. A putative mechanism for foam cell formation.

Although the accumulation of cholesterol in macrophages appears to be an initial step in atherogenesis, low-density lipoprotein (LDL), a major risk factor for atherosclerosis, does not promote cholesterol accumulation in macrophages in its native form. On the other hand, apolipoprotein (apo) A-I-containing lipoprotein removes cholesterol from cholesterol-loaded macrophages (foam cells) and prevents cholesterol from accumulating in the cells. We examined the effect of LDL on cholesterol removal by two species of apoA-I-containing lipoproteins, one containing only apoA-I (LpA-I) and the other containing apoA-I and apoA-II (LpA-I/A-II). When foam cells were incubated with LpA-I or LpA-I/A-II, cellular cholesterol mass was reduced. In contrast, when LDL was added, the cholesterol-reducing capacities of these lipoproteins were dose-dependently inhibited by LDL. In the presence of LDL, LpA-I and LpA-I/A-II removed free cholesterol preferentially from LDL rather than from the plasma membrane of foam cells. In addition, a fair amount of cellular cholesterol was directly moved to LDL rather than to LpA-I or LpA-I/A-II. The cellular cholesterol that moved to LDL was completely compensated for by the cholesterol influx from LDL to foam cells. Thus, net cholesterol efflux (a combination of influx and efflux) from foam cells was inhibited by LDL. These results, taken together, indicate that LDL may accelerate foam cell formation by inhibiting cholesterol removal from the cells and that elevated levels of plasma LDL may become a risk factor for atherosclerosis by inhibiting the function of LpA-I and LpA-I/A-II at the cellular level.

Animals↗
PubMed1993

Carbamyl phosphate synthetase I deficiency. One base substitution in an exon of the CPS I gene causes a 9-basepair deletion due to aberrant splicing.

Carbamyl phosphate synthetase I (CPS I; EC6,3,4,16) is an autosomal recessive disorder characterized by hyperammonemia. We studied the molecular bases of CPS I deficiency in a newborn Japanese girl with consanguineous parents. Northern and Western blots revealed a marked decrease in CPS I mRNA and enzyme protein but with a size similar to that of the control, respectively. Sequencing of the patient's cDNA revealed a nine-nucleotide deletion at position 832-840. Sequencing analysis of the genomic DNA revealed a G to C transversion at position 840, the last nucleotide of an exon in the splice donor site. This substitution altered the consensus sequence of the splice donor site and the newly cryptical donor site in the exon caused the 9-bp in-frame deletion. This report seems to be the first complete definition of CPS I deficiency, at the molecular level.

Amino Acid Sequence↗
PubMed1993

Establishment and characterization of a novel human monocytic leukemia cell line (KP-1) expressing scavenger receptor.

A new monocytic leukemia cell line (KP-1) was established from a 2-y-old Japanese girl with acute monocytic leukemia. The KP-1 cells were maintained in suspension culture with a doubling time of 96 h. The cells were positively stained with alpha-naphtyl butyrate esterase, but not with naphthol AS-D chloroacetate esterase, myeloperoxidase, and periodic acid-Schiff reagent. Cell surface marker analysis revealed that the cells were CD4, CD11a, CD11c, CD13, CD14, CD18, CD33, and HLA-DR positive. Karyotype analysis revealed near diploidy (47 XX) and a translocation t(11;19) was found. When treated with 12-o-tetradecanoylphorbol 13-acetate, KP-1 cells became tightly adherent, showed the enhanced reactivity for alpha-naphtyl butyrate esterase, and produced several monokines such as IL-1 beta, tumor necrosis factor-alpha, and macrophage colony-stimulating factor. Immunoelectron microscopy demonstrated that the human macrophage scavenger receptor was expressed after 12-o-tetradecanoylphorbol-13-acetate treatment, and the cells accumulated a large amount of cholesterol esters in the presence of acetylated LDL. Compared with another human monocytic leukemia cell line, THP-1, KP-1 expressed scavenger receptor and accumulated cholesterol ester more rapidly in the presence of 12-o-tetradecanoyl phorbol-13-acetate and acetylated LDL. Scatchard analysis using 125I-labeled acetylated LDL revealed a typical saturation curve with an apparent kd of 1.7 x 10(-7) M and 3400 binding sites per cell. KP-1 retained the characteristics of monocyte-macrophage lineage cells and will facilitate the in vitro studies of the pathologic and physiologic roles of scavenger receptors.

Antigens, Neoplasm↗
PubMed1993

Isolated angiitis of the central nervous system first presenting as intracranial hemorrhage during cesarean section.

A case of isolated angiitis of the central nervous system (CNS) which first presented as intracranial hemorrhage during cesarean section is reported. Only one case of isolated angiitis of the CNS in post partum has been reported to date. Although a headache in labor and puerperium usually suggests subarachnoid hemorrhage, isolated angiitis of the CNS should be considered in the differential diagnosis.

Adult↗
PubMed1993

[Adrenocorticotropin receptor in familial glucocorticoid deficiency].

Recent studies have revealed the presence of four subtypes for the melanocortin receptor (MC-R). Among these MC-Rs, MC2-R is considered to be an adrenocorticotropin (ACTH) receptor because its expression is almost localized in the adrenal cortex. Five Japanese patients with ACTH unresponsiveness were examined as to whether they have mutations in the putative ACTH receptor. Among these patients, there are two groups of siblings, each of which consists of two individuals. The coding region of the ACTH receptor gene was amplified by polymerase chain reaction and directly sequenced on both strands, however, no point mutation was found in any of the five patients, suggesting that familial glucocorticoid deficiency, caused by the mutated ACTH receptor, may be rare.

Adrenal Cortex↗
PubMed1993

[Gene analysis of maple syrup urine disease (MSUD)].

Maple syrup urine disease (MSUD), an autosomal recessive hereditary metabolic disorder, is due to defective oxidative decarboxylation of the branched-chain alpha-ketoacids (BCKAs) derived from transamination of the three branched-chain amino acids, valine, leucine and isoleucine. The oxidative decarboxylation of three BCKAs is catalysed by the branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex. BCKDH consists of three catalytic components: E1, E2 and E3. The E1 component is further composed of two subunits, E1 alpha and E1 beta. To clarify the mechanisms involved in MSUD, measurements of the enzyme activity in cultured cells, measurements of the generation time in cultured cells, complementation analysis and immunoblot analysis were performed. To further elucidate the molecular mechanisms of MSUD, we and others isolated and characterized cDNAs encoding BCKDH-E1 alpha, E1 beta, E2 and E3. The human genome structures of BCKDH -E1 alpha, E1 beta and E2 were also characterized. Gene mutations in E1 alpha, E1 beta and E2, respectively, were identified at the molecular level in three cases of classical MSUD. It became clear that the molecular mechanisms of MSUD involved not only the function of each subunit but also the protein-protein interactions between each subunit. In an attempt to further analyse the molecular basis of MSUD, we carried out complementation analyses by somatic cell hybridization, and identified the affected component of BCKDH complex in the MSUD patient. Furthermore, to rapidly screen for gene mutations, we used PCR-SSCP analysis. Seventeen patients with MSUD were examined using these methods. Defects of E1 alpha, E1 beta and E2 subunits were suspected in 8, 5, and 4 patients, respectively, by complementation analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1993

[Molecular basis of urea cycle disorders].

Five different enzymes, carbamyl phosphate synthetase I (CPS I), ornithine transcarbamylase (OTC) argininosuccinate synthetase (AS), argininosuccinate lyase (AL) and arginase (AR) play a role in urea synthesis from ammonium. The structures of cDNA of all these enzymes and those of genome DNA of some enzymes (OTC, AL, AR) have been already clarified, and using of the information, the alleles of each enzyme deficiency have been identified. Alleles are extremely heterogeneous in all enzyme deficiencies, in sharp difference from other inborn errors of metabolism, such as cystic fibrosis and hemoglobinopathies.

Alleles↗
PubMed1992

Post-translational processing of rac p21s is important both for their interaction with the GDP/GTP exchange proteins and for their activation of NADPH oxidase.

rac1 and rac2 p21s are ras p21-like small GTP-binding proteins which are implicated in the NADPH oxidase-catalyzed superoxide generation in phagocytes. rac1 and rac2 p21s have a Cys-A-A-Leu (A = aliphatic amino acid) structure in their C-terminal region which may undergo post-translational processing including prenylation, proteolysis, and carboxyl methylation. We studied the function of this post-translational processing of rac p21s in their interaction with the stimulatory and inhibitory GDP/GTP exchange proteins for rac p21s, named smg GDS and rho GDI, and in their NADPH oxidase activation. We produced human recombinant rac1 and rac2 p21s in insect cells and purified them from the membrane and soluble fractions as the post-translationally processed and unprocessed forms, respectively. Post-translationally processed rac1 and rac2 p21s were sensitive to both smg GDS and rho GDI, but post-translationally unprocessed rac1 and rac2 p21s were insensitive to them. The GTP gamma S (guanosine 5'-(3-O-thio)triphosphate)-bound form of post-translationally processed rac1 and rac2 p21s stimulated the NADPH oxidase activity, but post-translationally unprocessed rac1 and rac2 p21s were far less effective. These results indicate that both rac1 and rac2 p21s stimulate the NADPH oxidase activity and that their post-translational processing is important not only for their interaction with smg GDS and rho GDI but also for their NADPH oxidase activation.

Amino Acid Sequence↗
PubMed1992

Mutations in the Pit-1 gene in children with combined pituitary hormone deficiency.

Pit-1 is a pituitary-specific transcription factor that binds to and transactivates promoters of growth hormone and prolactin genes. In three unrelated Japanese children with combined pituitary hormone deficiency, we identified three point mutations in the Pit-1 gene, Pro24Leu, Arg143Gln, and Arg271Trp, located on the major transactivation region, POU-specific domain, and POU-homeodomain, respectively.

Amino Acid Sequence↗
PubMed1992

Characterization of the gene encoding human pituitary-specific transcription factor, Pit-1.

Pit-1 is a pituitary-specific transcription factor that binds to and transactivates promoters of growth hormone- and prolactin-encoding genes. A chromosomal gene related to human Pit-1 isolated from human gene libraries was over 14 kb long and split into six exons. All of the splice donor and acceptor sites conformed to the GT/AG rule. The gene was mapped to human chromosome region 3p11.

Base Sequence↗
PubMed1992

Primary structure deduced from complementary DNA sequence and expression in cultured cells of mammalian 4-hydroxyphenylpyruvic acid dioxygenase. Evidence that the enzyme is a homodimer of identical subunits homologous to rat liver-specific alloantigen F.

4-Hydroxyphenylpyruvic acid dioxygenase is an important enzyme in tyrosine catabolism in most organisms. From porcine and human liver cDNA libraries we isolated complementary DNA inserts for the enzyme. Protein sequence analysis of the porcine enzyme revealed a block of the amino terminus of the mature enzyme. Comparison of the amino acid sequence determined by Edman degradation of peptides derived from porcine liver 4-hydroxyphenylpyruvic acid dioxygenase with the nucleotide sequences revealed the primary structure of the porcine and human enzymes. The mature human and porcine enzymes have an 89% amino acid sequence identity in amino acid residues and are composed of 392 amino acid residues. A computer-assisted homology search revealed that the enzyme is 88% identical in amino acid sequence to rat liver-specific alloantigen F. A monoclonal antibody (mob 51), which can immunoprecipitate both the human and porcine enzymes, was developed. Cultured BMT-10 cells transfected with the cDNA insert of the human enzyme, using the expression vector pCAGGSneodE, produced a polypeptide with an M(r) of 43,000, which was immunoprecipitated with mob 51. Enzymic activity of the enzyme was detected in the transfected cells but not in the mock transfected cells. These findings suggest that the human 4-hydroxyphenylpyruvic acid dioxygenase is a homodimer of two identical subunits with an M(r) of 43,000. Liver-specific alloantigen F seems to be closely related to the enzyme or possibly to the subunit of the enzyme itself. Elucidation of the complete amino acid sequence of the enzyme is expected to reveal structure-function relationships of this metabolically important enzyme and to shed light on inherited disorders related to tyrosine metabolism, especially tyrosinemia types 1 and 3.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed1992

Differential effect of subspecies of lipoprotein containing apolipoprotein A-I on cholesterol efflux from cholesterol-loaded macrophages: functional correlation with lecithin: cholesterol acyltransferase.

Two species of lipoprotein containing apoA-I, one containing only apoA-I (LpA-I), and the other containing apoA-I and apoA-II (LpA-I/A-II), were tested for their effects on macrophage foam cells. Rat macrophages were converted to foam cells by incubation with radiolabeled acetylated LDL. Incubation with LpA-I or LpA-I/A-II decreased the cellular cholesteryl esters (CE) mass. However, the free cholesterol (FC) mass was only reduced by LpA-I. All the radioactivity excreted into the medium was associated with LpA-I or LpA-I/A-II; 39% of the excreted radioactivity was esterified in LpA-I and 10% in LpA-I/A-II. Upon complete inactivation of lecithin: cholesterol acyltransferase (LCAT) activity with dithiobisnitrobenzoic acid, the cholesterol reducing capacity of LpA-I was weakened significantly. However, the CE mass reducing capacity of LpA-I/A-II was not affected. When LpA-I and LpA-I/A-II were combined, the cholesterol reducing capacity of the mixture was similar to that of LpA-I alone. However, LpA-I re-isolated from the medium showed a lower esterification rate than did the re-isolated LpA-I/A-II, thereby indicating that the cholesterol esterified in LpA-I was transferred to LpA-I/A-II. These results suggest that (i) the function of LpA-I is closely linked to the LCAT activity while that of LpA-I/A-II is not, and (ii) LpA-I in concert with LpA-I/A-II induces a series of extracellular events; LCAT-mediated esterification of excreted FC by LpA-I and a subsequent CE transfer to LpA-I/A-II. These mechanisms might be important for net cholesterol efflux from macrophage foam cells in physiological states.

Adolescent↗
PubMed1992

Regulation of the superoxide-generating NADPH oxidase by a small GTP-binding protein and its stimulatory and inhibitory GDP/GTP exchange proteins.

The superoxide-generating NADPH oxidase system in phagocytes consists of at least membrane-associated cytochrome b558 and three cytosolic components named SOCI/NCF-3/sigma 1/C1, SOCII/NCF-1/p47-phox, and SO-CIII/NCF-2/p67-phox. p47-phox and p67-phox were isolated, and their primary structures were determined, but SOCI has not been well characterized. In the present study, we first purified SOCI to homogeneity from the cytosol fraction of the differentiated HL-60 cells. The purified SOCI was a small GTP-binding protein (G protein) with a M(r) of about 22,000. The guanosine 5'-(3-O-thio)triphosphate-bound form, but not the GDP-bound form, of this small G protein showed the SOCI activity. The partial amino acid sequence of SOCI thus far determined was identical to the amino acid sequence deduced from the cDNA encoding rac2 p21. None of the purified small G proteins, including Ki-ras p21, smg p21B/rap1B p21, rhoA p21, and rac1 p21, showed the SOCI activity. These results indicate that SOCI is a small G protein very similar, if not identical, to rac2 p21. The GDP/GTP exchange reaction of SOCI was stimulated and inhibited by stimulatory and inhibitory GDP/GTP exchange proteins for small G proteins, named smg GDS and rho GDI, respectively. The NADPH oxidase activity was also stimulated and inhibited by smg GDS and rho GDI, respectively. These results indicate that the superoxide-generating NADPH oxidase system is regulated by both smg GDS and rho GDI through rac2 p21 or the rac2-related small G protein in phagocytes.

Amino Acid Sequence↗
PubMed1992

Leukocyte adhesion deficiency: identification of novel mutations in two Japanese patients with a severe form.

Leukocyte adhesion deficiency is a disorder with mutations of the gene for the beta subunit, a component common to three adhesion molecules; LFA-1, Mac-1 and p150,95. The molecular basis of the disorder was studied in two patients with its severe form. In the first patient, the mutant gene expressed an aberrant mRNA, 1.2 kb longer than usual, resulting from a G to A substitution at the splice donor site of a 1.2 kb intron. Several aberrantly spliced messages, arising from splicing at cryptic donor sites, were also identified. The beta subunit proteins deduced from the mRNA sequences lacked half the carboxyl terminal portion. In the second patient, the mutation was a G to A transition at nucleotide 454, which resulted in an Asp128 to Asn substitution of the beta subunit. The 128th Asp residue is located in a region crucial for the association with alpha subunits and strictly conserved among the integrin beta subunits so far analyzed.

Adult↗
PubMed1992

An 11-base-pair DNA sequence motif apparently unique to the human interleukin 4 gene confers responsiveness to T-cell activation signals.

We have identified a DNA segment that confers responsiveness to antigen stimulation signals on the human interleukin (IL) 4 gene in Jurkat cells. The human IL-4 gene, of 10 kilobases, is composed of four exons and three introns. A cis-acting element (P sequence) resides in the 5' upstream region; no additional DNA segments with enhancer activity were identified in the human IL-4 gene. For further mapping purposes, a fusion promoter was constructed with the granulocyte/macrophage colony-stimulating factor basic promoter containing 60 base pairs of sequence upstream from the cap site of the mouse granulocyte/macrophage colony-stimulating factor gene and various lengths of the 5' upstream sequence of the IL-4 gene. The P sequence was located between positions -79 and -69 relative to the transcription start site of the human IL-4 gene, and this location was confirmed by base-substitution mutations. The plasmids carrying multiple copies of the P sequence showed higher responsiveness to the stimulation. The binding protein(s) that recognize the P sequence of the IL-4 gene were identified by DNA-mobility-shift assays. The binding of NF(P) (a DNA binding protein that specifically recognizes the P sequence) to the P sequence was abolished when oligonucleotides carrying base substitutions were used, indicating that the NF(P) interaction is sequence-specific and that binding specificity of the protein paralleled the sequence requirements for IL-4 expression in vivo. The P sequence does not share homology with the 5' upstream sequence of the IL-2 gene, even though surrounding sequences of the IL-4 gene share high homology with the IL-2 gene. We conclude that a different set of proteins recognize IL-2 and IL-4 genes.

Animals↗
PubMed1992

Gene analysis of Mennonite maple syrup urine disease kindred using primer-specified restriction map modification.

Maple syrup urine disease (MSUD) is an autosomal recessive inherited disease due to a deficiency of any of the subunits, E1 alpha, E1 beta or E2, of the branched-chain alpha-ketoacid dehydrogenase complex (BCKDH). A large Mennonite kindred of MSUD has been studied in Pennsylvania, USA. In the present investigation, genomes from 70 members, including 12 patients belonging to eight different Mennonite MSUD pedigrees, were examined for possible abnormalities in the E1 alpha gene of BCKDH, by primer-specified restriction map modification. A T-to-A substitution which generates an asparagine in place of a tyrosine at amino acid 394 of the mature E1 alpha subunit was present in both alleles in all the patients and in a single allele in all obligate carriers and several siblings. We describe a new technique for rapid and easy detection of the mutant gene in this population. These family studies provide additional evidence that Mennonite MSUD is caused by a missense mutation of the E1 alpha gene of BCKDH

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗