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Query: EC:1.4.3.13 (lysyl oxidase)
 1,248 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lysyl oxidase (EC 1.4.3.13) is a copper-dependent enzyme acting principally on collagen and elastin catalyzing the formation of aldehyde cross-links. It is also believed to possess a tumor suppressor activity as the anti-oncogene of ras. While rat, human, and mouse lysyl oxidase cDNAs have been cloned, little is known about the structure of the gene, its organization, or regulation. This paper describes the cloning of an intronic segment of the human lysyl oxidase gene. Sequence analysis defined the location of an intron that separates the prepro-coding segments from the segment encoding the catalytic domain. Genomic restriction mapping and gene copy number data established that multiple lysyl oxidase mRNA transcripts originate from a single gene and thus are products of alternative splicing. Northern analysis of adult and fetal fibroblast RNA showed a dominant approximately 4.3-kilobase lysyl oxidase mRNA transcript that varied in abundance as a function of cell line. These data are consistent with a complex mechanism regulating the expression of the lysyl oxidase gene.
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PMID:Characterization of the human lysyl oxidase gene locus. 135 76

Lysyl oxidase catalyzes the oxidation of lysine residues to alpha-aminoadipic-delta-semialdehyde. This is the first step in the covalent cross-linking of collagen and tropoelastin and results in the formation of insoluble collagen and elastic fibers in the extracellular matrix. We have characterized the complete nucleotide sequence of human lysyl oxidase (EC 1.4.3.13) and compared the derived amino acid sequence (417-amino acids) to rat lysyl oxidase and the mouse ras recision gene (rrg). 88% of amino acids and 83% of nucleotides were conserved between human and rat lysyl oxidase. The mouse ras recision gene demonstrated 89% conservation of amino acids with human lysyl oxidase. The sequence conservation was not evenly distributed along the molecule. The carboxy terminus of the protein, which contains the putative copper binding sites and is likely to be the catalytically active domain, was more highly conserved than the amino terminus. The 89% amino acid sequence similarity between the murine ras recision gene and human lysyl oxidase suggests that they are the same gene product. Therefore, in addition to cross linking of extracellular matrix proteins, lysyl oxidase may have a direct role in tumor suppression. Northern blot analysis of poly A+RNA from cultured skin fibroblasts revealed at least three-distinct transcripts, sized 4.8 kb, 3.8 kb and 2.0 kb. In addition, using a panel of human mouse cell hybrids, the lysyl oxidase gene was assigned to human chromosome 5.
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PMID:The complete derived amino acid sequence of human lysyl oxidase and assignment of the gene to chromosome 5 (extensive sequence homology with the murine ras recision gene). 135 35

Changes in chromatin supraorganization defined in terms of patterns of chromatin texture were studied by video image analysis in Feulgen-stained revertants of LTR-ras-transformed NIH 3T3 cells and in cell lines obtained by transfection of these revertants with sense and antisense constructs of the lysyl oxidase gene (also named Lox or "ras recision gene"). The objective was to determine whether changes in expression of the Lox gene, which have been assumed to modulate cell transformation by ras, could also affect the chromatin supraorganization changes known to be elicited in NIH 3T3 cells by ras transformation. The image analysis results revealed that, although a nuclear phenotype visually similar to the most frequent one (III) in ras-transformed NIH 3T3 cells also appeared in the revertant, it contained a remarkably less tight chromatin packing state. This situation was also found in the revertant transfected with the sense construct of the Lox gene, but in the revertant transfected with the Lox antisense constructs the chromatin texture of the III phenotype was equal to or close to that of the ras-transformed cells. With regard to the nuclear phenotype characterized by abundant loosely packed chromatin and less represented in the transformed cell lines (I'), changes in the various cell lines, although detectable, were not as drastic as those reported for the III phenotype. The enhancement in chromatin condensation of the type III nuclei, which affects euchromatin, is probably associated with a limited transcription of the genome. Although the image analysis results are mostly in agreement with previously published data on the molecular biology and tumorigenicity of the same cell lines, it appears that the phenomenon of chromatin condensation once established in NIH 3T3 cells by LTR-ras transformation could not be totally reverted by simply affecting Lox expression.
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PMID:Modulation of ras transformation affecting chromatin supraorganization as assessed by image analysis. 755 46

Neoplastic transformation mediated by ras oncogenes is associated with down-regulation of gene expression. We have constructed a subtracted complementary DNA library from preneoplastic rat 208F fibroblasts by hybridizing with mRNA from a ras-transformed subclone. One of the complementary DNA clones identified by this approach encodes the 3' end of lysyl oxidase, the homologue of the mouse ras recision gene. Expression of lysyl oxidase was almost completely down-regulated in two clones of H-ras-transformed 208F cells (FE-8 and FE-56). We isolated a set of spontaneous phenotypic revertants of FE-8 cells (designated FSR) by cloning at limiting dilution. FSR revertant clones expressed high levels of lysyl oxidase and H-ras mRNA but grew only poorly in semisolid agar medium as opposed to anchorage-independent parental FE-8 cells. We obtained subclones of FSR cells which displayed again the transformed morphology of FE-8 cells but required anchorage for growth and continued to express high levels of lysyl oxidase mRNA. Thus, expression of lysyl oxidase correlated with the suppression of anchorage-independent growth rather than with flat morphology. Lysyl oxidase might be a useful marker to distinguish between different aspects of reversion and transformation.
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PMID:Up-regulation of lysyl oxidase in spontaneous revertants of H-ras-transformed rat fibroblasts. 769

Neoplastic transformation mediated by ras oncogenes is associated with deregulated expression of genes encoding, for example, various proteases, lysyl oxidase, and smooth-muscle alpha-actin. To define the role of these genes in the initiation or maintenance of the ras-transformed state, we compared their steady-state mRNA levels in two different sets of preneoplastic fibroblast lines, ras-transformed clones, and phenotypic revertants derived from them. Compared with the preneoplastic fibroblasts, the ras-transformed derivatives exhibited elevated levels of cathepsin L (major excreted protein), transin (stromelysin I, matrix metalloproteinase-3), and collagenase I (matrix metalloproteinase-1) mRNA but undetectable levels of lysyl oxidase mRNA. Partial restoration of lysyl oxidase transcription was observed in four of five phenotypic revertants derived from rat FE-8 and NIHpEJcl3 cells. The elevated levels of transin mRNA found in NIHpEJcl3 cells were diminished to the pretransformation level in interferon revertants but were not reduced in phenotypic rat FE-8 revertants expressing a high level of the ras oncoprotein. High steady-state levels of collagenase I mRNA were dependent on ras expression but were not closely associated with the transformed phenotype. High levels of cathepsin L mRNA were associated with neither high ras expression nor neoplastic transformation. The downregulation of smooth-muscle alpha-actin, characteristic of transformed cell lines, was not reversible in phenotypic revertants.
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PMID:Partial restoration of pre-transformation levels of lysyl oxidase and transin mRNAs in phenotypic ras revertants. 772 41

Adipocyte differentiation of 3T3-L1 cells is a complex process which is inhibited by retinoic acid (RA). Since RA acts by nuclear receptors which directly regulate gene expression, we postulate that the primary targets of RA action in this system are genes which are regulated early in adipose conversion. In this study, we demonstrate the use of the differential display technique to search for early events in adipose commitment which are sensitive to RA. A mRNA was identified on the basis of its RA-dependent gene expression 24 h after initiation of a standard differentiation protocol. Molecular cloning of the cDNA revealed it to be identical to the ras recision gene (rrg), for lysyl oxidase. Indeed, two mRNAs identical to those recognized by lysyl oxidase probes were expressed in preadipocytes and tandemly repressed with 24 h of exposure to differentiation conditions. Lysyl oxidase activity was similarly reduced in the media of differentiated cells. RA completely blocked the differ-entiation-related reduction in rrg/lysyl oxidase gene expression, although RA had no independent stimulatory effect on rrg/lysyl oxidase expression in cells not exposed to differentiating conditions. Thus, differential display has been successfully used to identify rrg/lysyl oxidase as an early marker for adipose conversion that is responsive to RA.
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PMID:Retinoic acid prevents downregulation of ras recision gene/lysyl oxidase early in adipocyte differentiation. 786 96

Transforming growth factor(TGF)beta 1 is a potent inhibitor of growth in mouse osteoblastic MC3T3-E1 cells. To isolate genes that are induced by TGF beta 1, the differential screening method was adopted using a cDNA library constructed from cells treated with TGF beta 1 for 4 h. Six independent cDNA clones were isolated (TGF beta-stimulated clone, TSC-5, TSC-36, TSC-115, TSC-128, TSC-160 and TSC-161), the expression of which was increased by TGF beta 1-treatment with maximal expression at 6-10 h. The steady-state levels of TSC-36, TSC-128 and TSC-160 increased almost tenfold, whereas those of TSC-5, TSC-115 and TSC-161 were elevated at most threefold. From partial nucleotide sequences, TSC-160 was found to be identical to rrg (ras-recision gene, lysyl oxidase), and TSC-115 had 80% similarity with tropomyosin cDNA, whereas other genes seemed novel. Expression of TSC-36 and TSC-160 was dramatically decreased in v-Ki-ras-transformed MC3T3 cells or in transformed NIH 3T3 cells (DT), and was recovered to normal levels in a flat revertant (C11). A nearly full-length copy of TSC-36 cDNA was isolated, and an open reading frame indicated that it encodes a protein of 35 kDa. An antiserum was raised against the C-terminal peptide predicted from the nucleotide sequence, and a polypeptide with an approximate molecular mass of 38 kDa was detected in cultured medium of MC3T3-E1 cells. The amino acid sequence of TSC-36 protein was found to have some similarity with follistatin, an activin-binding protein, and a limited similarity with the secreted protein rich in cysteine (SPARC).
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PMID:Cloning from a mouse osteoblastic cell line of a set of transforming-growth-factor-beta 1-regulated genes, one of which seems to encode a follistatin-related polypeptide. 790 Oct 4

Lysyl oxidase (EC 1.4.3.13), a copper-dependent enzyme which catalyses the formation of aldehyde cross-links, and acts primarily on collagen and elastin, is known to be increased during wound healing and in fibrotic disorders including liver cirrhosis and atherosclerosis, and to be decreased in some hereditary connective tissue diseases and in malignant cell lines. A recent study showed that lysyl oxidase might possess tumour suppressor activity as an antioncogene for ras. Little is known about the localization of this enzyme in human skin. In this study, we determined immunohistochemically the localization of lysyl oxidase in normal skin of young and elderly subjects obtained from sun-exposed and unexposed regions of the body. All skin samples tested had similar distributions of lysyl oxidase. The enzyme was present both extracellularly and intracellularly. Extracellularly, a few granular aggregates of immunoreactants were observed along collagen and elastic fibres. These granules were more common in the adventitial portion of the dermis than in the reticular portion. Of all sun-exposed and unexposed regions studied, the skin of the face displayed the greatest amount of extracellular immunoreactants. Immunopositive granules were observed intracellularly in fibroblasts, vascular endothelial cells, sweat glands, sebaceous glands, arrector pili muscles and some keratinocytes. These findings provide evidence that, as suggested in recent reports, lysyl oxidase may have a variety of intracellular functions.
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PMID:Immunohistochemical localization of lysyl oxidase in normal human skin. 791 5

Lysyl oxidase initiates crosslink formation of the connective tissue matrix. This enzyme can also revert the ras phenotype in mouse NIH 3T3-transformed cells. Even though lysyl oxidase may participate in many different biological processes, its chromosomal assignment in the mouse genome remains to be addressed. Southern analysis of a panel of Chinese hamster x mouse somatic cell hybrids was utilized to assign the lysyl oxidase gene (Lox) to mouse Chromosome 18.
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PMID:The mouse lysyl oxidase gene (Lox) resides on chromosome 18. 809 46

Lysyl oxidase, an extracellular enzyme involved in the maturation of collagen and elastin, also appears to function as a phenotypic suppressor of transformation by the ras gene product, p21. Genomic clones of the mouse lysyl oxidase gene have been isolated, analyzed, and sequenced. Lysyl oxidase appears to be a single-copy gene, organized into seven exons and six introns, and spans approximately 14 kb of the mouse genome. The gene encodes two messages, sized at about 4.8 and 3.8 kb, that differ in the length of the untranslated sequence at the 3' end of the gene. All of the 3' untranslated sequence and the polyadenylation signals are contained in exon VII; there is no evidence of alternate splicing. Primer extension and ribonuclease protection experiments revealed two sites of transcription initiation in a region with sequence motifs characteristic of a promoter, which was upstream and adjacent to the 5' untranslated sequence found in the cDNA.
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PMID:Structure of the mouse lysyl oxidase gene. 810 Feb 14


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