Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Scar tissue found at the site of myocardial infarction (MI) contains phenotypically transformed fibroblast-like cells termed myofibroblasts (myoFb). In injured cardiac tissue, autoradiography and immunolabeling have localized high density angiotensin (Ang) converting enzyme (ACE) and Ang II receptor binding to these cells, suggesting that they may regulate local concentrations of Ang II and transduce signals at this site. Ang II is known to modulate type I collagen gene expression of fibroblasts and myoFb, and to promote fibrous tissue contraction, each of which may contribute to tissue repair. It is unknown whether myoFb themselves generate Ang peptides de novo via expression of angiotensinogen (Ao), an aspartyl protease needed to convert Ao to Ang I, and ACE. We therefore isolated and cultured myoFb from 4-week-old scar tissue of the adult rat left ventricle with transmural MI. In cultured myoFb we found: (a) immunoreactive membrane-bound ACE, cytosolic cathepsin D (Cat-D), and AT, receptors by immunofluorescence and confocal microscopy, (b) mRNA expression for Ao, ACE, and Cat-D, but not renin, by reverse transcriptase-polymerase chain reaction, (c) production of Ang I and II in serum-free culture media; (d) absence of renin activity; (e) a time-dependent conversion of Ao to Ang I by myoFb cytosol, which was inhibited by pepstatin A, but not by renin inhibitor; and (f) significant increase in Ang II production (P < 0.05) by exogenous Ao and Ang I (10 nM), which was significantly blocked by lisinopril (0.1 microM: P < 0.05). Thus, cultured myoFb express requisite components and are able to generate Ang I and II de novo. In an autocrine and/or paracrine manner, Ang II may regulate myoFb collagen turnover and fibrous tissue contraction.
J Mol Cell Cardiol 1997 May
PMID:Cultured myofibroblasts generate angiotensin peptides de novo. 920 23

As indices of triple helix stability of type I collagen CNBr peptide homotrimers, deltaG degrees for monomer-trimer transitions and melting temperatures were obtained from circular dichroism measurements at increasing temperatures. The data were compared with the stability of the parent native molecule. Peptides were found to have a lower stability than the whole collagen molecule. The general implication is that the coordinated water molecules play a key role in determining collagen triple helical stability and high cooperativity at melting. Other factors (monomer stability, ionic and hydrophobic factors, variations of composition, specific sequences) could also contribute towards peptide stability; these factors could explain the data obtained in the case of peptide alpha1(I) CB3.
J Mol Biol 1997 Jun 20
PMID:Stability of type I collagen CNBr peptide trimers. 921 54

Type I collagen is the most prevalent member of the fibril forming family of collagens in higher vertebrates and its heterotrimeric form is comprised of two alpha 1(I) chains and one alpha2(I) polypeptide chain. The functional importance of having two distinct chain types in type I collagen is largely undefined. The existence of a mouse model with a Cola-2 gene mutation (termed oim) that results in non-functional pro alpha 2(I) chains presents a unique opportunity to explore changes in collagen structure resulting from the complete (oim/oim mice) and partial (oim/+ mice) loss of functional alpha 2(I) chains. Tail tendon is a tissue with a well-defined, hierarchical organization of type I collagen. X-ray diffraction studies on oim/oim versus control tendons indicate that the total absence of alpha 2(I) chains results in a decrease in the order of axial packing and a loss of crystalline lateral packing. This suggests that the non-equivalence of three chains is an important determinant of lateral interactions between adjacent molecules and may be involved in the long-range axial order in type I collagen-containing tissues. Both homotrimeric and heterotrimeric type I collagen molecules are found in heterozygous oim mice and these appear to be present in the same co-polymeric fibrils, preventing crystalline lateral packing. In addition to these changes at a fibrillar level, the absence of the alpha 2(I) chain results in an increased enzymatic susceptibility at one site. The oim/oim mice are observed to have reduced body size and smaller tendon bundles, which may be a consequence of these molecular and fibrillar changes in collagen. Furthermore, it is likely that a similar alteration in the molecular packing of collagen in bone fibrils contributes to the osteopenia and decreased bone strength in mice with the oim mutation that are also characteristic of human osteogenesis imperfecta.
J Mol Biol 1997 Jul 11
PMID:Altered collagen structure in mouse tail tendon lacking the alpha 2(I) chain. 923 28

Individual spermatozoa from the father of two affected infants with osteogenesis imperfecta were separated by dilution and micromanipulation. A segment of the type I collagen gene containing the mutant region was amplified by nested polymerase chain reaction and sequenced. Among 40 individual spermatozoa, 15 specimens were identified as mutants with a substitution of guanine3208 to adenine (glycine862 to serine) while 18 and seven specimens were of the wild and mixed types respectively. Through this study, we have established a molecular procedure that can be considered as prerequisite for preimplantation diagnosis of genetic disorders with a single point mutation.
Mol Hum Reprod 1996 Feb
PMID:Identification of a Gly862 to Ser substitution in the type I collagen gene from a single spermatozoon. 923 70

The adhesion of platelets and other cells to type I collagen is mediated by the alpha 2 beta 1 integrin. A binding site for the alpha 2 beta 1 integrin within the alpha 1(I) collagen chain has previously been localized to the cyanogen bromide fragment alpha 1(I)-CB3. We noe show by use of inhibitory monoclonal antibodies against the alpha 2 beta 1 integrin, that platelets also adhere to purified alpha 2(I) collagen chains by a mechanism mediated by the alpha 2 beta 1 integrin. Moreover, following isolation of cyanogen bromide fragments of the alpha 2(I) collagen chain by HPLC, we demonstrate that alpha 2 beta 1 integrin-mediated adhesion is restricted to the CB4 fragment of the alpha 2(I) collagen polypeptide. These findings indicate the presence of at least two spatially distinct binding sites for the alpha 2 beta 1 integrin on the native type I collagen triple helix.
Biochem Mol Biol Int 1997 Jul
PMID:The alpha 2 beta 1 integrin binds to the CB4 peptide of the alpha 2(I) collagen chain. 924 15

The hepatic stellate cell (HSC) is the primary cell responsible for the dramatic increase in the synthesis of type I collagen in the cirrhotic liver. Quiescent HSCs contain a low level of collagen alpha1(I) mRNA, while activated HSCs contain about 60- to 70-fold more of this mRNA. The transcription rate of the collagen alpha1(I) gene is only two fold higher in activated HSCs than in quiescent HSCs. In assays using actinomycin D or 5,6-dichlorobenzimidazole riboside collagen alpha1(I) mRNA has estimated half-lives of 1.5 h in quiescent HSCs and 24 h in activated HSCs. Thus, this 16-fold change in mRNA stability is primarily responsible for the increase in collagen alpha1(I) mRNA steady-state level in activated HSCs. We have identified a novel RNA-protein interaction targeted to the C-rich sequence in the collagen alpha1(I) mRNA 3' untranslated region (UTR). This sequence is localized 24 nucleotides 3' to the stop codon. In transient transfection experiments, mutation of this sequence diminished accumulation of an mRNA transcribed from a collagen alpha1(I) minigene and in stable transfections decreased the half-life of collagen alpha1(I) minigene mRNA. Binding to the collagen alpha1(I) 3' UTR is present in cytoplasmic extracts of activated but not quiescent HSCs. It contains as a subunit alphaCP, which is also found in the complex involved in stabilization of alpha-globin mRNA. The auxiliary factors necessary to promote binding of alphaCP to the collagen 3' UTR are distinct from the factors necessary for binding to the alpha-globin sequence. Since alphaCP is expressed in both quiescent and activated HSCs, these auxiliary factors are responsible for the differentially expressed RNA-protein interaction at the collagen alpha1(I) mRNA 3' UTR.
Mol Cell Biol 1997 Sep
PMID:Posttranscriptional regulation of collagen alpha1(I) mRNA in hepatic stellate cells. 927 98

To obtain some insight into the extracellular matrix in the human placenta, we investigated the composition of collagens purified from the placentae of patients with pre-eclampsia and compared it with normal placentae. Collagen was extracted from the placentae of both normal and pre-eclampsia pregnancies during the third trimester. The relative amounts of various collagens were evaluated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The ratio of the intensity of the band corresponding to the alpha 1 (III) chain with that of the alpha 1 (I) chain in placentae of pre-eclampsia was significantly lower than in normal placentae (P < 0.05). In contrast, the ratio of the intensity of the band corresponding to the alpha 1 (V) chain with that of the alpha 1 (I) chain in placentae of pre-eclampsia was significantly higher than in normal placentae (P < 0.05). The results suggest that an increased level of type V collagen relative to type I collagen in the placentae of pre-eclampsia might be closely associated with the disturbance to trophoblastic cell functions and the supply of nutrients to the developing fetus necessary for the maintenance of pregnancy.
Mol Hum Reprod 1997 Aug
PMID:Increase in the relative level of type V collagen in the placentae of patients with pre-eclampsia. 929 58

We examined the type I collagen synthesized by cultured dermal fibroblasts from a patient affected with osteogenesis imperfecta (OI) type IV. Both normal and abnormal trimers were produced. The mutant collagen molecules were excessively modified intracellularly, had a melting temperature 4 degrees C lower than the control, were secreted at a reduced rate, and underwent delayed processing to mature alpha chains.Molecular investigations identified a G --> A transition in one COL1A2 allele, resulting in a Gly922 --> Ser substitution in the alpha2(I) chain. The proband's mutation was demonstrated to arise "de novo" by the absence of the mutant allele restriction enzyme pattern from parental genomic DNA.We analyzed the insoluble extracellular matrix deposited by long-term cultured fibroblasts from our patient and from a previously described unrelated individual who carries an identical substitution. In both cases, the mutant chain constituted 10-15% of the total alpha chains deposited.We also present here the first detailed comparison of phenotype between unrelated OI patients with an identical collagen mutation. These two patients are both Caucasian females, ages 8 and 9 years, each diagnosed as type IV OI by the Sillence classification. They have a similar phenotype including moderate skeletal fragility with several femur fractures, dentinogenesis imperfecta, wormian bone, and reduced height and weight. We conclude that this phenotype is related both to the location of this mutation and to the similar extent of matrix incorporation by the mutant chains. Molecular and biochemical studies of unrelated individuals with identical amino acid substitutions in type I collagen resulting in either similar or dissimilar clinical outcomes will make a significant contribution to identifying the factors involved in the modulation of the OI phenotype.
Biochem Mol Med 1997 Oct
PMID:Phenotypic comparison of an osteogenesis imperfecta type IV proband with a de novo alpha2(I) Gly922 --> Ser substitution in type I collagen and an unrelated patient with an identical mutation. 936 95

Plasma collagen-binding vitronectin was assayed in 62 patients with chronic liver disease and 14 healthy control subjects. It was measured by an enzyme immunoassay using type I collagen and monoclonal antibody to vitronectin before and after treatment with heparin or dextran sulfate in vitro. The pretreatment level of plasma collagen-binding vitronectin (mean +/- S.E.M.) was 5.5 +/- 0.5 micrograms/ml in the controls, 8.2 +/- 0.3 micrograms/ml in chronic persistent hepatitis, 8.3 +/- 0.7 micrograms/ml in chronic active hepatitis, 7.9 +/- 0.7 micrograms/ml in liver cirrhosis, and 8.2 +/- 0.5 micrograms/ml in hepatocellular carcinoma with cirrhosis. After treatment with heparin, the percent collagen-binding vitronectin to total vitronectin was 20.6 +/- 2.0% in the controls, 24.7 +/- 4.1% in chronic persistent hepatitis, 28.6 +/- 2.5% in chronic active hepatitis, 42.6 +/- 4.5% in liver cirrhosis, and 31.8 +/- 2.3% in hepatocellular carcinoma. All percents were significantly increased compared to the pretreatment percent. The same pattern was also found after dextran sulfate treatment. Compared to that in the pretreatment state, the collagen-binding vitronectin after these treatments was more closely correlated with the serum levels of 7S collagen and hyaluronic acid. These results suggest that the collagen-binding activity of vitronectin may play an important role in the progression of liver disease and/or fibrosis through its activation with some glycosaminoglycans.
Res Commun Mol Pathol Pharmacol 1997 Sep
PMID:Plasma collagen-binding vitronectin activated by heparin and dextran sulfate in chronic liver disease. 938 91

X-ray diffraction of rat tail tendon shows that type I collagen fibrils contain regions of three-dimensional crystalline arrays; where molecular packing is speculated to be by a staggered sheet or microfibril arrangement. The X-ray diffraction pattern also contains a significant amount of diffuse scatter indicative of static and thermal disorder in fibrils. Removal of the diffuse scatter from the equatorial region of X-ray diffraction patterns obtained using synchrotron radiation allowed the Bragg intensities to be viewed on a flat background. Indexing of Bragg peak intensity on the 10, -10, 0 -1, 01, -11 and 1-1 row-lines of the triclinic unit cell have been used here to test possible sheet and microfibril packing arrangements. The relative translation of molecular segments in the gap and overlap regions as well as the telopeptide orientation have been investigated. A global search through combinations of molecular packing and molecular translation revealed that the sheet-type conformations cannot account for the observed low-angle off-meridional Bragg peak intensity distribution. A superior fit is obtained with D-staggered left-handed microfibril structures. The orientation of the telopeptides may indicate that there are interconnections between microfibrils that may explain the difficulty in isolating individual microfibrillar structures.
J Mol Biol 1998 Jan 16
PMID:Molecular packing of type I collagen in tendon. 946 8


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