Biomedical subjects

K Takahara

Publications and source records attributed to K Takahara.

At least 37 records · Page 2Linked to original sources

PubMed1996

Bone morphogenetic protein-1: the type I procollagen C-proteinase.

Bone morphogenetic proteins (BMPs) are bone-derived factors capable of inducing ectopic bone formation. Unlike other BMPs, BMP-1 is not like transforming growth factor-beta (TGF-beta), but it is the prototype of a family of putative proteases implicated in pattern formation during development in diverse organisms. Although some members of this group, such as Drosophila tolloid (TLD), are postulated to activate TGF-beta-like proteins, actual substrates are unknown. Procollagen C-proteinase (PCP) cleaves the COOH-propeptides of procollagens I, II, and III to yield the major fibrous components of vertebrate extracellular matrix. Here it is shown that BMP-1 and PCP are identical. This demonstration of enzymatic activity for a BMP-1/TLD-like protein links an enzyme involved in matrix deposition to genes involved in pattern formation.

Amino Acid Sequence↗

PubMed1996

Fine mapping of the human and mouse genes for the type I procollagen COOH-terminal proteinase enhancer protein.

The human gene (PCOLCE) for the C-proteinase enhancer, a glycoprotein that enhances the enzymatic activity that cleaves the type I procollagen C-propeptide, was previously mapped to the same cytogenetic region (7q21.3-q22) as COL1A2, the type I collagen pro-alpha 2 chain gene. The apparent proximity of these two genes, whose products interact, might have reflected some mechanism for coregulation of expression. We have employed somatic cell hybrids, cosmid contigs, and interspecific backcross mice to investigate further the apparent proximity of the two genes. Our data show that PCOLCE and COL1A2 are separated by at least 6 Mb on human chromosome 7q and that Pcolce and Col1a2 are located on two separate chromosomes in mouse. These data also indicate that PCOLCE is located within a 10- to 15-cM region of conserved synteny between human chromosome 7 and mouse chromosome 5.

Animals↗

PubMed1996

Mouse and human homologues of the yeast origin of replication recognition complex subunit ORC2 and chromosomal localization of the cognate human gene ORC2L.

ORC2 is a subunit of the origin recognition complex in yeast and has been implicated in the initiation of DNA replication and transcriptional silencing. We have isolated mouse and human cDNA clones encoding proteins with 47.9 and 46.3% similarity, respectively, to yeast ORC2. This degree of similarity and the alignment of sequences suggest that these clones may represent a mammalian ORC2 homologue. The existence of such a homologue would, in turn, suggest the existence of a mammalian origin recognition complex, similar to that found in yeast. Although Northern blot analysis of various adult mouse tissues found the highest levels of expression of ORC2-like (ORC2L) RNA in testes, strong signals did not always correspond to tissues in which high levels of DNA replication would be expected. This finding may reflect functional roles of ORC2L distinct from those that it may play in DNA replication. Analyses of somatic cell hybrid DNA and fluorescence in situ hybridization were employed to map the human ORC2L gene to chromosome 2q33.

Amino Acid Sequence↗

PubMed1996

A translocation interrupts the COL5A1 gene in a patient with Ehlers-Danlos syndrome and hypomelanosis of Ito.

Ehlers-Danlos syndrome (EDS) is a genetically and pathogenetically heterogeneous group of disorders of which at least 11 types have been described. All are connective tissue disorders characterized by defects of the skin, ligaments and blood vessels with the clinical spectrum ranging from innocuous findings to lethality. Mutations in the genes encoding the major fibrillar collagen types I and III have been demonstrated in EDS types VII and IV, respectively, while mutations in the lysyl hydroxylase and ATP7A genes, with roles in collagen cross-linking, are responsible for EDS types VI and IX. The biochemical and molecular bases for the most common forms of EDS (types I, II and III) are unknown. Here, we describe a balanced translocation between chromosome 9 and an X chromosome that disrupts the minor fibrillar collagen type V gene COL5A1 in a patient with both EDS type I and hypomelanosis of Ito. The breakpoint occurs at 9q34 within COL5A1 intron 24 and interestingly, within a LINE-1 (L1) element at Xp21.1. A fusion mRNA between COL5A1 and an Alu sequence is produced, but no aberrant protein is detectable. Rather, the amount of type V collagen is reduced in the patient's fibroblasts, suggesting haploinsufficiency as a cuase of the phenotype. This demonstrates that a mutation in a type V collagen gene, COL5A1, results in EDS type I, and shows the involvement of L1 sequences in a constitutional chromosomal translocation. Because collagen type V is a heteromorphic protein in which molecules may be composed of polypeptides encoded by three COL5A genes, this suggests all three genes as candidates for mutations in EDS.

Base Sequence↗

PubMed1996

Failure of ventral body wall closure in mouse embryos lacking a procollagen C-proteinase encoded by Bmp1, a mammalian gene related to Drosophila tolloid.

The mouse bone morphogenetic protein1 (Bmp1) gene encodes a secreted astacin metalloprotease that cleaves the COOH-propeptide of procollagen I, II and III. BMP-1 is also related to the product of the Drosophila patterning gene, tolloid (tld), which enhances the activity of the TGFbeta-related growth factor Decapentaplegic and promotes development of the dorsalmost amnioserosa. We have disrupted the mouse Bmp1 gene by deleting DNA sequences encoding the active site of the astacin-like protease domain common to all splice variants. Homozygous mutant embryos appear to have a normal skeleton, apart from reduced ossification of certain skull bones. However, they have a persistent herniation of the gut in the umbilical region and do not survive beyond birth. Analysis of the amnion of homozygous mutant embryos reveals the absence of the fold that normally tightly encloses the physiological hernia of the gut. At the electron microscopic level, the extracellular matrix of the amnion contains collagen fibrils with an abnormal morphology, consistent with the incorporation of partially processed procollagen molecules. Metabolical labelling and immunofluorescence studies also reveal abnormal processing and deposition of procollagen by homozygous mutant fibroblasts in culture.

Amnion↗

PubMed1995

Complete structural organization of the human alpha 1 (V) collagen gene (COL5A1): divergence from the conserved organization of other characterized fibrillar collagen genes.

Genes that encode the vertebrate fibrillar collagen types I-III have previously been shown to share a highly conserved intron/exon organization, thought to reflect common ancestry and evolutionary pressures at the protein level. We report here the complete intron/exon organization of COL5A1, the human gene that encodes the alpha 1 chain of fibrillar collagen type V. The structure of COL5A1 is shown to be considerably diverged from the conserved structure of the genes for fibrillar collagen types I-III. COL5A1 has 66 exons, which is greater than the number of exons found in the genes for collagen types I-III. The increased number of exons is partly due to the increased size of the pro-alpha 1(V) N-propeptide, relative to the sizes of the N-propeptides of the types I-III procollagen molecules. In addition, however, the increased number of exons is due to differences in the intron/exon organization of the triple-helix coding region of COL5A1 compared to the organization of the triple-helix coding regions of the genes for collagen types I-III. Of particular interest is the increase of 54 bp exons in this region of COL5A1, strongly supporting the proposal that the triple-helix coding regions of fibrillar collagen genes evolved from duplication of a 54 bp primordial genetic element. Moreover, comparison of the structure of COL5A1 to the highly conserved structure of the genes of collagen types I-III provides insights into the probable structure of the ancestral gene that gave rise to what appears to be two classes of vertebrate fibrillar collagen genes.

Amino Acid Sequence↗

PubMed1995

Structural organization and genetic localization of the human bone morphogenetic protein 1/mammalian tolloid gene.

Bone morphogenetic protein 1 (BMP1) is a putative protease purified from extracts capable of inducing ectopic bone formation. A single mammalian gene apparently encodes alternatively spliced transcripts for BMP1, for a longer protein with a domain structure identical to that of the Drosophila dorsal-ventral patterning gene product tolloid (Tld), and for a third species of low abundance. Here we describe the organization of the 46-kb, 22-exon human BMP1/mTld gene that encodes these forms. Exons corresponding to each of the alternatively spliced transcripts are identified, and comparison with the Drosophila Tld gene reveals alignment of introns at only three positions. The major BMP1/mTld transcription start site is found only 706 bp downstream of the polyadenylation site of the SFTP2 surfactant gene, and a previously reported highly polymorphic CA repeat is found within the BMP1/mTld first intron. These two findings place the BMP1/mTld gene between markers D8S298 and D8S5 on the genetic map.

Alternative Splicing↗

PubMed1995

The association among fat distribution, physical fitness, and the risk factors of cardiovascular disease in obese women.

The purpose of this study was to see whether fat distribution and physical fitness are independent risk factors of cardiovascular diseases in obese women. Seventy-four obese women aged 19 to 65 years participated in this study. The data were collected on plasma lipid profiles, plasma glucose and insulin during an oral glucose tolerance test, blood pressure, fat distribution determined by the waist to hip ratio (WHR), total body fat determined by the hydrostatic weighing method and a direct measurement of blood lactate threshold. Significant correlations were found between WHR and plasma cholesterol (TC), plasma LDL cholesterol (LDL-c) and LDL-c to the plasma HDL cholesterol ratio (LDL-c/HDL-c), independent of age, percent body fat, and VO2 per lean body mass at blood lactate threshold (LT). On the other hand, LT was significantly related to the area under the curve of insulin during OGTT (insulin area) and DBP, independent of age, percent body fat, and WHR. In conclusion, both fat distribution and physical fitness are considered to be independently related to some important risk factors in obese women after adjustment for percent body fat.

Adipose Tissue↗

PubMed1994

Bone morphogenetic protein-1 and a mammalian tolloid homologue (mTld) are encoded by alternatively spliced transcripts which are differentially expressed in some tissues.

Bone morphogenetic protein-1 (BMP-1) is a metalloprotease purified from extracts capable of inducing ectopic bone formation. In humans, it has a domain structure similar to that of the Drosophila dorsal-ventral patterning gene-product tolloid (Tld), but is considerably shorter. Here we show that, in humans and mice, alternatively spliced transcripts encode BMP-1 and a longer protein, designated mammalian tolloid (mTld), with a domain structure identical to that of Drosophila Tld. A third alternatively spliced product, in which a novel domain is inserted near the BMP-1 C terminus, is also reported. Low levels of transcripts for mTld were found in all adult human tissues surveyed, while BMP-1 transcripts were detectable in all adult tissues except brain. This differential expression was mirrored in embryonic mouse tissues where in situ hybridization found high levels of mTld transcripts, but was unable to detect BMP-1 transcripts, in the floor plate of the neural tube of the developing central nervous system. The third alternatively spliced form was not detected in adult human tissues. In situ hybridizations found punctate signals for all three forms localized to trophoblast giant cells in 17.5-day mouse placenta, with highest levels of expression, especially for BMP-1, near the maternal interface.

Alternative Splicing↗

PubMed1994

Type I procollagen COOH-terminal proteinase enhancer protein: identification, primary structure, and chromosomal localization of the cognate human gene (PCOLCE).

Type I procollagen COOH-terminal proteinase (C-proteinase) enhancer, a glycoprotein that binds to the COOH-terminal propeptide of type I procollagen and enhances procollagen C-proteinase activity, was purified from mouse fibroblast culture media. Partial amino acid sequences obtained from proteolytic fragments were found to have identity with the deduced amino acid sequence of a cDNA clone of unknown function, previously isolated from a mouse astrocyte library. Sequences of mouse enhancer cDNA, obtained in the present study, predict a approximately 50-kDa, 468-amino acid protein that differs from the 43-kDa, 402-amino acid protein predicted by the previously reported astrocyte-derived clone. Human cDNAs encode an enhancer of 449 amino acids. Previous biochemical studies have found the mouse enhancer as a 55-kDa form, which is readily processed to 36- and 34-kDa forms, retaining full C-proteinase enhancing activity and the ability to bind the COOH-terminal propeptide. Data presented here show the 36-kDa form to correspond to the amino-terminal portion of the 55-kDa protein. This is the most conserved region between mouse and human enhancers, comprising two domains with homology to domains found in a number of proteases and proteins with developmental functions. Such domains are thought to mediate interactions between proteins. Mouse enhancer RNA is shown to be at highest levels in collagen-rich tissues, especially tendon. The human enhancer gene, PCOLCE, is localized to 7q21.3-->q22, the same chromosomal region containing the type I collagen alpha 2 chain gene, COL1A2.

Amino Acid Sequence↗

PubMed1994

Effect of low dose aspirin on augmented plasminogen activator inhibitor type 1 activity in patients with permanent pacemakers.

To clarify the activity states of coagulation and fibrinolysis in patients with a permanent pacemaker, we studied 29 patients more than 4 months after operation. They were divided into a single pacemaker lead group (S, n = 14) and a double lead group (D, n = 15). Prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin III, tissue-type plasminogen activator (tPA) activity, plasminogen activator inhibitor type-1 (PAI-1) activity, and platelet aggregation were measured and compared to those in an age-matched control group (C, n = 7). The effects of low dose aspirin (81 mg/day) in the patients (n = 21) were also studied 2 weeks after administration. PAI-1 activity in groups S and D was significantly higher than that in the group C (53.5 +/- 36.5, 86.8 +/- 59.2 ng/mL vs 19.4 +/- 7.2 ng/mL; P < 0.01 and P < 0.005). Platelet aggregation induced by collagen was slightly higher in groups S and D than group C. Other parameters were not significantly different. In the patients, low dose aspirin significantly suppressed collagen induced platelet aggregation (71.8 +/- 20.3% vs 41.7 +/- 28.3%; P < 0.005), but not PAI-1 activity. tPA activity was increased significantly by the low dose aspirin administration (3.94 +/- 1.85 ng/mL vs 2.48 +/- 1.19 ng/mL; P < 0.005). Thus, PAI-1 activity in patients with a permanent pacemaker is elevated, and the activity is not suppressed by low dose aspirin unlike the platelet aggregation.

Adult↗

PubMed1994

Alternative splicing of bovine terminal deoxynucleotidyl transferase cDNA.

Two cDNA fragments of terminal deoxynucleotidyl transferase, which contained new insertion sequences, were found from bovine thymus cDNA. One of the clones encoded 18 new amino acids and the other encoded 9 new amino acids. In the results of genomic structure analysis around the new insertion sequences, alternative splicing of the bovine terminal deoxynucleotidyl transferase gene was suggested.

Alternative Splicing↗

PubMed1993

The egg nucleus regulates the behavior of sperm nuclei as well as cycling of MPF in physiologically polyspermic newt eggs.

The possible role of the egg nucleus in regulating the behavior of sperm nuclei and the cycling of maturation-promoting factor (MPF) was investigated in the physiologically polyspermic eggs of the newt Cynops pyrrhogaster. Many sperm entered all areas of the egg, but only one sperm pronucleus, the principal sperm pronucleus, moved to the center of the animal hemisphere to form a zygote nucleus with the egg pronucleus. All sperm and egg pronuclei synthesized DNA, but the zygote nucleus completed the synthesis of DNA 0.5-1 hr earlier than the accessory sperm nuclei. Entrance into M phase by the accessory sperm nuclei was delayed to a greater and greater extent with increasing distance of these nuclei from the zygote nucleus. When DNA in the egg nucleus was damaged by uv irradiation, not only were both prophase and M phase in the zygote nucleus prolonged, but also the MPF cycle was delayed. Some accessory sperm nuclei in the animal hemisphere escaped degeneration to form additional bipolar spindles, so that delayed multipolar cleavage occurred. The MPF activity in the vegetal hemisphere was less than 25% of that found in the animal hemisphere at M phase in normally fertilized eggs. The levels of immunologically detectable proteins that contained the sequence PSTAIR in vegetal hemispheres were less than 25% of those in animal hemispheres. These results indicate that the egg nucleus of the Cynops egg is involved in the control of the activation of MPF and that the accessory sperm nuclei in the vegetal hemisphere degenerate as a result of the lack of components that are indispensable for entry into M phase.

Animals↗

PubMed1992

[The significance of obesity in UOEH medical students--multiple regression analysis of the annual physical checkup data in 1991].

For the purpose of evaluating the significance of obesity in a young population as a risk factor toward various chronic diseases, a multiple regression analysis was performed on the data from the annual physical checkup of medical students of UOEH in 1991. The following results were obtained. (1) The average obesity index of the students showed a progressive and significant increase in the past 13 years from 1979 to 1991. (2) A close correlation between the obesity index and serum GPT was recognized by elevation of the standard partial regression coefficient of serum GPT to obesity index and that of obesity index to serum GPT when the data from all 617 students was analysed in one group. This finding was intensified in 142 obese students with an obesity index of over 10%, but it was not seen in the remaining non-obese students. (3) The correlation between the obesity index and serum GPT was found solely in the group of students with constant obesity; i.e., whose obesity index was always more than 10% during a maximum of 9 years in the past. (4) Systolic blood pressure was related to the red blood cell count rather than to the obesity index in this young population. (5) No particularly close correlation to serum cholesterol was found with any of 10 representative items examined in this physical checkup, including the obesity index, indicating that the other factors should be related to serum cholesterol levels. From the above findings, it can be concluded that constant obesity in students is related to liver dysfunction, probably due to fatty liver frequently seen in the precise examination of these individuals.

Adolescent↗

PubMed1992

Effects of fibronectin-type V collagen recombinant fusion protein on cell adhesion and cell proliferation.

An expression vector pTF7520-Col-V-In, which encodes a fusion protein of the cell-binding domain of fibronectin (C277) and the insulin- and heparin-binding domain of the alpha 1 chain of human type V collagen, was constructed. E. coli transfected with this plasmid synthesized a 50-kDa fusion protein. This fusion protein, C277-V, was purified from the crude extract by a single step heparin HPLC. Similar amounts of insulin bound to purified C277-V and to the alpha 1 chain of type V collagen as judged by the binding of peroxidase-conjugated insulin. Cell-adhesive activity of C277-V was lower than that of the original fibronectin fragment C274, but similar numbers of cells adhered to both protein substrates when the culture dishes were coated with 1 mM of each protein. Insulin bound to the C277-V substratum stimulated the growth of mouse mammary tumor MTD cells in serum-free culture medium.

Amino Acid Sequence↗

PubMed1992

Proteoglycan obtained from bovine aorta suppress thrombin-induced platelet aggregation.

Proteoglycan (PG), isolated and purified from bovine aorta (intima-media), consisted of 68.6% chondroitin 4/6-sulfate (CS 4/6-S), 30% dermatan sulfate (DS), 1.4% heparan sulfate (HS), and a trace of hyaluronic acid (HA). PG did not affect platelet aggregation induced by ADP, collagen, and epinephrine, but inhibited that induced by thrombin. Of the standard GAGs investigated, hyaluronic acid (HA) and CS-4/6-S slightly inhibited only thrombin-induced platelet aggregation. However, PG and standard GAGs did not affect the thrombin induced aggregation of washed platelets. The effect of PG after papain digestion on thrombin-induced platelet aggregation was less potent than that before. It is suggested by the results of this study that PG in the aorta inactivates plasma thrombin, probably by inhibiting thrombin activators or potentiating substances which inactivate thrombin and that these effect of PG would be mainly due to PG-DS and partly due to PG-HS.

Animals↗

PubMed1991

Complete primary structure of human collagen alpha 1 (V) chain.

Several cDNA clones, encoding prepropeptide of human collagen alpha 1(V) chain, have been isolated. The prepropeptide (1838 amino acids length) of the alpha 1(V) chain was composed of a putative signal peptide, a large NH2-terminal noncollagenous region, a main collagenous region, and a COOH-terminal noncollagenous region. The signal peptide contained many leucine residues. The NH2-terminal noncollagenous region was much larger than those of the other collagens and had a region homologous to the COOH-terminal domain of laminin A chain, but it did not contain a cysteine-rich region that was maintained in the region of the other collagens. This region also contained probable tyrosine sulfation sites, and short collagenous sequences that were interrupted by three noncollagenous segments. The main collagenous region of the alpha 1(V) chain consisted of 338 repeats of Gly-X-Y-triplet. This region had a high degree (82%) of homology with the amino acids of the collagen alpha 1(XI) chain. The COOH-terminal noncollagenous region resembled that of the alpha 1(XI) chain, too, and 8 residues of cysteine that were important for the formation of the triple helix structure of collagens were observed. These results suggest that the alpha 1(V) chain belongs to the fibrillar collagen relative to the alpha 1(XI) chain, but codon usage of the alpha 1(V) cDNA was clearly different from those of the other fibrillar collagens including the alpha 1(XI), while it was similar to type IV collagen. This result supposes a different evolution of the alpha 1(V) gene from those of the other fibrillar collagens.

Amino Acid Sequence↗

PubMed1991

Insulin binds to type V collagen with retention of mitogenic activity.

The abilities of eight extracellular matrix proteins, fibronectin, vitronectin, laminin, and collagen types I, II, III, IV, and V to bind insulin were examined by binding studies with insulin conjugated with peroxidase. At a physiological pH and ionic strength, type V collagen bound to insulin most strongly. The other types of collagen, laminin, and vitronectin also bound insulin with affinity lower than that of type V collagen. The insulin-binding site of type V collagen was in a 30-kDa CNBr fragment of the alpha 1 (V) chain. Analysis of the amino acid sequence showed that this 30-kDa fragment was identical to the heparin-binding fragment of type V collagen. The insulin-binding sites of laminin and vitronectin were located in the A chain and in the heparin-binding domain, respectively. Insulin bound to type V collagen stimulated the synthesis of DNA by mouse mammary tumor MTD cells, indicating that bound insulin retained mitogenic activity.

Amino Acid Sequence↗