Lysyl oxidase-like 2 (LOXL2) and E47 EMT factor: novel partners in E-cadherin repression and early metastasis colonization

Epithelial-mesenchymal transition (EMT) has been associated with increased aggressiveness and acquisition of migratory properties providing tumor cells with the ability to invade into adjacent tissues. Downregulation of E-cadherin, a hallmark of EMT, is mediated by several transcription factors (EMT-TFs) that act also as EMT inducers, among them, Snail1 and the bHLH transcription factor E47. We previously described lysyl oxidase-like 2 (LOXL2), a member of the lysyl oxidase family, as a Snail1 regulator and EMT inducer. Here we show that LOXL2 is also an E47-interacting partner and functionally collaborates in the repression of E-cadherin promoter. Loss and gain of function analyses combined with in vivo studies in syngeneic breast cancer models demonstrate the participation of LOXL2 and E47 in tumor growth and their requirement for lung metastasis. Furthermore, LOXL2 and E47 contribute to early steps of metastatic colonization by cell and noncell autonomous functions regulating the recruitment of bone marrow progenitor cells to the lungs and by direct transcriptional regulation of fibronectin and cytokines TNFα, ANG-1 and GM-CSF. Moreover, fibronectin and GM-CSF proved to be necessary for LOXL2/E47-mediated modulation of tumor growth and lung metastasis.

GATA3 inhibits lysyl oxidase-mediated metastases of human basal triple-negative breast cancer cells

Discovery of mechanisms that impede the aggressive and metastatic phenotype of human basal triple-negative type breast cancers (BTNBC) could provide novel targets for therapy for this form of breast cancer that has a relatively poor prognosis. Previous studies have demonstrated that the expression of GATA3, the master transcriptional regulator of mammary luminal differentiation, can reduce the tumorigenicity and metastatic propensity of the human BTNBC MDA-MB-231 cell line (MB231), although the mechanism for reduced metastases was not elucidated. We demonstrate through gene expression profiling that GATA3 expression in 231 cells resulted in the dramatic reduction in the expression of Lysyl oxidase (LOX), a metastasis-promoting matrix remodeling protein, in part, through methylation of the LOX promoter. Suppression of LOX expression by GATA3 was further confirmed in the BTNBC Hs578T cell line. Conversely, reduction of GATA3 expression by siRNA in luminal BT474 cells increased LOX expression. Reconstitution of LOX expression in 231-GATA3 cells restored metastatic propensity. A strong inverse association between high LOX and low GATA3 expression was confirmed in a panel of 51 human breast cancer cell lines. Similarly, human breast cancer microarray data demonstrated that high LOX/low GATA3 expression is associated with the BTNBC subtype of breast cancer and poor patient prognosis. Expression of GATA3 reprograms BTNBC to a less aggressive phenotype and inhibits a major mechanism of metastasis through inhibition of LOX. Induction of GATA3 in BTNBC cells or novel approaches that inhibit LOX expression or activity could be important strategies for treating BTNBC.

Catalytic properties and structural components of lysyl oxidase

Key aspects of the biosynthesis and catalytic specificity of lysyl oxidase (LO) have been explored. Oxidation of peptidyl lysine in synthetic oligopeptides is markedly sensitive to the presence of vicinal dicarboxylic ami/no acid residues. Optimal activity is obtained with the -Glu-Lys- sequence within a polyglycine 11-mer, whereas the -Lys-Glu- sequence is much less efficiently oxidized. The -Asp-Glu-Lys- sequence is a very poor substrate, although this sequence is oxidized in type I collagen fibrils. These results are considered in the light of a model requiring collagen to be assembled as fibrils prior to oxidation by LO. An in vitro system for the expression of catalytically active LO has been devised. Deletion or inclusion of the cDNA coding for the propeptide region in the expressed construct results in apparently identical, catalytically active enzyme products, indicating the lack of essentiality of this region for active enzyme production. These effects are considered with respect to the conservation of the amino acid sequence of LO produced by different species.

Selective upregulation and amplification of the lysyl oxidase like-4 (LOXL4) gene in head and neck squamous cell carcinoma

Members of the lysyl oxidase family (LOX) are copper and lysyl-tyrosine quinone cofactor-containing amine oxidases that are important for the assembly and maintenance of components of the extracellular matrix. Our previous results demonstrated that a novel member, LOXL4, is overexpressed in head and neck squamous cell carcinoma (HNSCC) compared to normal squamous epithelium. Results of the current study showed overexpression of the LOXL4 transcript in 74% (46 of 62) of invasive HNSCC tumours and 90% of both primary and metastatic HNSCC cell lines. Significant correlation was found between LOXL4 expression and local lymph node metastases versus primary tumour types (p<0.01) and higher tumour stages (p<0.01). Immunocytochemistry demonstrated cellular overexpression of the LOXL4 protein that correlated with the increased mRNA transcription in HNSCC cells. HNSCC cell lines displayed in significant subset of nuclei increased copies of the LOX4 gene locus on chromosome 10q24, demonstrated by fluorescence in situ hybridization (FISH). Extensive metaphase cytogenetic analysis was performed on UTSCC19A cells, identifying an isochromosome i(10)(q10). Taken together, these results highlight LOXL4 expression as a distinctive trait and suggest a functional role for LOXL4 in the molecular pathogenesis of invasive head and neck carcinomas.

[Mapping of a deletion interval on 8p21-22 in prostate cancer by gene dosage PCR]

Various microsatellite and CGH studies in prostate cancer identify deletions on the short arm of chromosome 8 especially at band 8p21-22 searching for unknown putative tumor suppressor genes. By means of microsatellite markers several candidate genes were detected which may play different roles in early prostate cancer progression. We established a quantitative gene dosage PCR based on the real time PCR method serving the purpose of genomic fine mapping. Therefore we used 10 Assays-on Demand (ABI) for the detection of deletions located between and nearby the microsatellite markers D8S258 and NEFL spanning a genomic region of approximate 7 mbp. Comparative immunohistochemical analysis from tissue micro arrays (TMA) of 1122 independent cases followed. We were able to detect three clearly separated deletion intervals on 8p21-22. One on LZTS1, second on NEFL and third a deletion hot spot on LOXL2, which was affected in 72% of all investigated cases. Our comparative immunohistochemical TMA based studies demonstrate that LOXL2 is nearly lost in most prostate cancer tissues. LOXL2 catalyze the crosslinking of collagen and elastin in the extracellular matrix and it has been assumed that it is involved in tumor suppression and cell adhesion. LOXL2 is frequently expressed in proliferating tissues and shows a high expression in benign prostate tissue too. In prostate cancer the expression is positive correlated with the MIB1-score.

Structural and functional diversity of lysyl oxidase and the LOX-like proteins

Lysyl oxidase (LOX) and four lysyl oxidase-like proteins, LOXL, LOXL2, LOXL3 and LOXL4, each contain a copper binding site, conserved lysyl and tyrosyl residues that may contribute to quinone co-factor formation, and a cytokine receptor-like domain. Each protein differs mainly in their N-terminal sequence, which may confer individual functions. Processing of the LOX proteins by BMP-1 and possibly other mechanisms may result in multiple functional forms. Splicing, reported for LOXL3, may also generate additional variants with unique functions. Each LOX, with its individual, developmentally regulated tissue and cell-specific expression and localization, results in a complex structural and functional variation for the LOX amine oxidases. The presence of only two LOX-like proteins in Drosophila, each with distinct spatial and temporal expression, allows for the assignment of individual function to one of these amine oxidases. Comparative expression analysis of each LOX protein is presented to help determine their functional significance.

Lysyl oxidases: a novel multifunctional amine oxidase family

Lysyl oxidase (LOX), a copper-containing amine oxidase, belongs to a heterogeneous family of enzymes that oxidize primary amine substrates to reactive aldehydes. LOX has been traditionally known for one function, the extracellular catalysis of lysine-derived cross-links in fibrillar collagens and elastin. More recently, diverse roles have been attributed to lysyl oxidase and these novel activities cover a spectrum of diverse biological functions such as developmental regulation, tumor suppression, cell motility, and cellular senescence. Lysyl oxidase has also been shown to have both intracellular and intranuclear locations. The multifunctional properties of lysyl oxidase (LOX) and our recent discovery of three novel members of this amine oxidase family, LOX-like (LOXL), LOXL2, and LOXL3, indicate the possibility that these varied functions are performed in both intracellular and extracellular environments by individual novel members of the LOX amine-oxidase family. Structural similarities of the highly conserved copper-binding and lysyl-tyrosylquinone cofactor sites among the LOX and LOX-like proteins may result in similar amine oxidase activities. However, specific novel functions, such as a potential role in cell adhesion and cell growth control, will be determined by other, conserved domains such as the cytokine receptor-like domain that is shared by all LOXs and by multiple scavenger receptor cysteine-rich (SRCR) domains present in LOXL2 and LOXL3. Furthermore, these functions may be carried out in a temporally and spatially regulated fashion.

Free radical spin trap alpha-phenyl-N-tert-butyl-nitron inhibits caspase-3 activation and reduces brain damage following a severe forebrain ischemic injury

It has been documented that alpha-phenyl-N-tert-butyl-nitron (PBN) possesses a potent neuroprotective effect when administered after transient focal cerebral ischemia. However, contradicting results were reported regarding its effect in transient global ischemia. To further elucidate the mechanism of PBN action, we have studied the effect of PBN on animal survival, histopathological outcome, and activation of caspase-3 following 30 min of global ischemia in vehicle- and PBN-treated rats. The results showed that 30 min of global ischemia was such a severe insult that no animal could survive beyond 2 d of reperfusion. Histopathological evaluation showed severe tissue edema and microinfarct foci in the neocortex and thalamus. Close to 100% damage was observed in the stratum and hippocampal CA1, CA3, and dentate gyrus subregions. Postischemic PBN treatment significantly enhanced animal survival and reduced damage in the neocortex, thalamus, and hippocampus. Immunohistochemistry demonstrated that caspase-3 was activated following ischemia in the striatum and the neocortex. PBN suppressed the activation of caspase-3 in both structures. It is concluded that PBN is a potent neuroprotectant against both focal and global ischemia; besides its function as a free radical scavenger, PBN may reduce ischemic brain damage by blocking cell death pathways that involve caspase-3 activation.

A novel human lysyl oxidase-like gene (LOXL4) on chromosome 10q24 has an altered scavenger receptor cysteine rich domain

We have identified a novel 14-exon human lysyl oxidase-like gene, LOXL4, on chromosome 10q24. The cDNA and derived amino acid sequence of LOXL4 demonstrates a conserved C-terminal region including the characteristic copper-binding site, lysyl and tyrosyl residues and a cytokine receptor-like domain. One of the four N-terminal SRCR domains contains a 13 amino acid insertion encoded by a short exon not present within the closely homologous LOXL2 and LOXL3 genes. The 3.5-kb LOXL4 mRNA is present in pancreas and testis and at lower levels in several other tissues. Fibroblasts, smooth muscle and osteosarcoma (HOS) cells express LOXL4. No expression was detected in HCT-116 and DLD-1 colon, MCF-7 breast and DU-145 prostate cancer cell lines.

Characterization of the region encompassing the human lysyl oxidase locus

A 46,823 bp region of human chromosome 5q23.1 encompassing the seven-exon lysyl oxidase gene was characterized at the primary sequence level. Approximately 17.4% of this region is comprised of repetitive elements. The gene colocalizes with microsatellite marker D5S467. It is flanked by two candidate nuclear matrix association regions (MARs). The 5' MAR centered at position 12,500 is of the AT-rich and curved DNA class. This is followed by a large CpG island containing fifty-seven putative regulatory elements which extend from just upstream of exon 1 to intron 2. The larger 3' MAR, spans position 35,050-39,750 and is characterized by a TG-rich kinked structure that also contains a topoisomerase II binding site. Based on these results model of the transcriptional regulation of the lysy/oxidase gene is presented.

Does long-term glucose infusion reduce brain damage after transient cerebral ischemia?

A recent study reported that hyperglycemia of a brief duration worsens, and of long duration reduces, ischemic brain damage. To test whether this is a valid conception, we induced 10 min of transient forebrain ischemia, recorded postischemic seizures, and evaluated brain morphology. The results showed that administration of glucose 2 h before ischemia aggravated brain damage, induced seizures, and caused animal death in the same manner as was previously observed when glucose was given 30 min before ischemia. Thus, the conclusion that the influence of glucose on an ischemic transient is dependent upon the duration of hyperglycemia is unsubstantiated.

A novel human gene (SARM) at chromosome 17q11 encodes a protein with a SAM motif and structural similarity to Armadillo/beta-catenin that is conserved in mouse, Drosophila, and Caenorhabditis elegans

A novel human gene, SARM, encodes the orthologue of a Drosophila protein (CG7915) and contains a unique combination of the sterile alpha (SAM) and the HEAT/Armadillo motifs. The SARM gene was identified on chromosome 17q11, between markers D17S783 and D17S841 on BAC clone AC002094, which also included a HERV repeat and keratin-18-like, MAC30, TNFAIP1, HSPC017, and vitronectin genes in addition to three unknown genes. The mouse SARM gene was located on a mouse chromosome 11 BAC clone (AC002324). The SARM gene is 1.8 kb centromeric to the vitronectin gene, and the two genes share a promoter region that directs a high level of liver-specific expression of both the SARM and the vitronectin genes. In addition to the liver, the SARM gene was highly expressed in the kidney. A 0.4-kb antisense transcript was coordinately expressed with the SARM gene in the kidney and liver, while in the brain and malignant cell lines, it appeared independent of SARM gene transcription. The SARM gene encodes a protein of 690 amino acids. Based on amino acid sequence homology, we have identified a SAM motif within this derived protein. Structure modeling and protein folding recognition studies confirmed the presence of alpha-alpha right-handed superhelix-like folds consistent with the structure of the Armadillo and HEAT repeats of the beta-catenin and importin protein families. Both motifs are known to be involved in protein-protein interactions promoting the formation of diverse protein complexes. We have identified the same conserved SAM/Armadillo motif combination in the mouse, Drosophila, and Caenorhabditis elegans SARM proteins.

Mutations in the lysyl oxidase gene are not associated with amyotrophic lateral sclerosis

BACKGROUND

There is an urgent need to identify genes involved in familial ALS (FALS), as mutations in the CuZn superoxide dismutase (SOD1) gene can account for 20% of FALS cases. The mechanisms by which the many mutations in the SOD1 gene lead to motoneuron degeneration are unknown, although current experimental evidence supports a toxic gain of function, possibly through copper-induced cytotoxicity. Copper is an integral component of a number of enzymes as well as SOD1. Since abnormalities in connective tissue cross-linking have been reported in ALS patients, an enzyme of possible relevance is lysyl oxidase (LOX), a copper-containing enzyme which catalyses the crosslinking of collagens and elastin. The aim of this study was to investigate the hypothesis that allelic variants or mutants of LOX gene result in altered function of LOX in ALS patients.

METHODS

The coding regions of the LOX gene were screened for polymorphism and mutations in a cohort of sporadic and familial ALS patients.

RESULTS

A novel polymorphism, Pro159Gln, was identified in eight individuals with sporadic ALS (5.0%) and five controls (3.6%). The previously identified Arg158Gln polymorphism was also detected in ALS patients and controls. These polymorphisms were genotyped in 192 ALS patients, including 31 unrelated familial cases and 138 controls, and no association was found between any of these polymorphisms and amyotrophic lateral sclerosis or its phenotype.

CONCLUSION

Mutations in the LOX gene are unlikely to be directly causative of ALS.

Central nervous system, uterus, heart, and leukocyte expression of the LOXL3 gene, encoding a novel lysyl oxidase-like protein

A BLASTN search using the mouse lor-2 cDNA identified three overlapping ESTs (AI752772, AA852888, and R55706) in the GenBank database. These expressed sequence tags were assembled into a contig of 3121 nucleotides with an open reading frame of 2262 bp. The encoded putative polypeptide of 754 amino acids presented all structural characteristics of the lysyl oxidase (LOX) enzyme family, a copper-binding site with four histidyl residues, the lysyl and tyrosyl residues known to be involved in LOX enzyme in the formation of the quinone cofactor and surrounding sequences, and the cytokine receptor-like domain. In addition, four scavenger receptor cysteine-rich (SRCR) domains were found in the N-terminal region of the protein. The gene encoding this new cDNA, which we have referred to as human lysyl oxidase-like 3 (humanLOXL3), has been mapped to chromosome 2p13.3, overlapping at its 3' end the HtrA2 serine protease gene. The structure of the humanLOXL3 gene was deduced from the BAC clone bac91a19 sequence and contained 14 exons. The expression pattern of this new member of the LOX gene family appears to be different from that of the LOX and LOX-like genes, as the central nervous system, neurons, and also leukocytes expressed humanLOXL3. A BLASTN search of the human EST database indicated the presence of ESTs, corresponding to alternative splice variants of LOXL3, that lacked exon 5 and exon 8. The putative resulting protein retained the region encoding the structural and functional elements of the amine oxidase but the second and fourth SRCR domains were truncated and the potential BMP-1 cleavage site was not present. The presence of domains unrelated to the traditional amine oxidase activity is a strong indication that humanLOXL3 might fulfill other functions in addition to intrinsic enzyme activity.

Intrathecal cyclosporin prolongs survival of late-stage ALS mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by upper and lower motor neuron death with ascending paralysis leading to death. In a transgenic mouse model of ALS (SOD1-G93A) weakness appears at 3 months of age, and because of progressive paralysis leads to death by 5 months. Cyclosporin A (CsA) is well known, for its extracerebral effect, as an immunosuppressant in organ transplantation. When able to access the brain, CsA is an effective neuroprotective agent mainly due to its protection of mitochondria through inhibition of the mitochondrial permeability transition. CsA does not cross the intact blood-brain barrier and was in the present study delivered to the brain through an infusion into the lateral cerebral ventricle. Injections started at the onset of late disease when weakness of the hindlimbs was apparent. CsA treatment prolonged the survival of ALS transgenic mice as compared to vehicle-treated controls. This finding implicates mitochondrial function in ALS and may have significance for human disease.

Additional complexity on human chromosome 15q: identification of a set of newly recognized duplicons (LCR15) on 15q11-q13, 15q24, and 15q26

Several cytogenetic alterations affect the distal part of the long arm of human chromosome 15, including recurrent rearrangements between 12p13 and 15q25, which cause congenital fibrosarcoma (CFS). We present here the construction of a BAC/PAC contig map that spans 2 Mb from the neurotrophin-3 receptor (NTRK3) gene region on 15q25.3 to the proximal end of the Bloom's syndrome region on 15q26.1, and the identification of a set of new chromosome 15 duplicons. The contig reveals the existence of several regions of sequence similarity with other chromosomes (6q, 7p, and 12p) and with other 15q cytogenetic bands (15q11-q13 and 15q24). One region of similarity maps on 15q11-q13, close to the Prader-Willi/Angelman syndromes (PWS/AS) imprinting center. The 12p similar sequence maps on 12p13, at a distance to the ets variant 6 (ETV6) gene that is equivalent on 15q26.1 to the distance to the NTRK3 gene. These two genes are the targets of the CFS recurrent translocations, suggesting that misalignments between these two chromosomes regions could facilitate recombination. The most striking similarity identified is based on a low copy repeat sequence, mainly present on human chromosome 15 (LCR15), which could be considered a newly recognized duplicon. At least 10 copies of this duplicon are present on chromosome 15, mainly on 15q24 and 15q26. One copy is located close to a HERC2 sequence on the distal end of the PWS/AS region, three around the lysyl oxidase-like (LOXL1) gene on 15q24, and three on 15q26, one of which close to the IQ motif containing GTPase-activating protein 1 (IQGAP1) gene on 15q26.1. These LCR15 span between 13 and 22 kb and contain high identities with the golgin-like protein (GLP) and the SH3 domain-containing protein (SH3P18) gene sequences and have the characteristics of duplicons. Because duplicons flank chromosome regions that are rearranged in human genomic disorders, the LCR15 described here could represent new elements of rearrangements affecting different regions of human chromosome 15q.

Lysyl oxidases: expression in the fetal membranes and placenta

The cross-linking of the connective tissues in the fetal membranes and placenta is important for their tensile strength and elasticity. We have studied the expression of lysyl oxidase (LOX) because it is the classical enzyme responsible for the cross-linking of collagen and elastin. We have also studied the two recently described, genetically distinct lysyl oxidase-like genes and proteins, lysyl oxidase-like (LOXL) and lysyl oxidase-like 2 (LOXL2), of unknown functions. Specific antisera have been used for immunolocalization in fetal membranes and placentae from early pregnancy terminations and after caesarean section at both preterm and term, prior to labour. In addition, the steady state mRNA levels of the three genes has been quantitated in separated amnion, chorion, decidua and placentae collected at term before labour. The immunocytochemistry shows that the spatial expression of the three lysyl oxidases is similar in early pregnancy in both the fetal membranes and placentae. However, by preterm this pattern had diverged and becomes greatest at term. The expression of the genes found at term was similar to the results of protein expression obtained by immunocytochemistry, with the exception of LOXL which had high placental gene expression, but low levels of immunolocalized protein. Thus by term, LOX was expressed predominantly in the amniotic epithelium, with little expression in the placenta, while LOXL showed highest gene expression in the placenta and lowest expression in the amnion. LOXL2 expression was again different and was expressed predominantly in the chorionic cytotrophoblast of the membranes with low expression in both the amnion and placentae. These results suggest that these three members of the lysyl oxidase family may have similar roles in early pregnancy during the development of the placenta and fetal membranes, but their divergence as pregnancy advances to term, may reflect changes in substrate specificity and connective tissue composition.

Novel glycosides from noni (Morinda citrifolia)

Three new glycosides were isolated from the fruits of noni (Morinda citrifolia). Their structures were determined to be 6-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose (1), 6-O-(beta-D-glucopyranosyl)-1-O-hexanoyl-beta-D-glucopyranose (2), and 3-methylbut-3-enyl 6-O-beta-D-glucopyranosyl-beta-D-glucopyranoside (3) using MS and NMR methods.

Altered bladder function in transgenic mice expressing rat elastin

The elasticity of tissues subjected to repeated deformation is provided by the presence of elastic fibers in the extracellular matrix (ECM). The most abundant component of elastic fibers is elastin, whose soluble precursor is tropoelastin. To establish the role elastin plays in the bladder, this study describes the biosynthetic, histologic, and physiologic consequences of expression of an isoform of rat tropoelastin in transgenic mouse bladder. The polymerase chain reaction (PCR) was used to determine expression of a rat tropoelastin minigene in transgenic mice. Histochemical methods were used to demonstrate changes in elastic fibers in frozen sections of bladder. Cystometric analysis was carried out in transgenic and non-transgenic mice, prior to and after 3 weeks of partial outlet obstruction. The PCR assay demonstrated that bladder tissue of transgenic mice expressed rat tropoelastin mRNA, whereas non-transgenes did not. Increased deposition of elastic fibers was demonstrated with the Verhoeff-van Gieson stain. Bladders of transgenic animals were more compliant than bladders of their non-transgenic littermates. Partial outlet obstruction resulted in increased bladder volume and more compliant bladders in non-transgenic mice. In contrast, the bladder volume and compliance in transgenes was almost unchanged by obstruction. This study demonstrates that normal elastic fiber assembly is prerequisite for the compliant properties of the bladder wall. Moreover, the response of the bladder to obstruction is critically influenced by elastin synthesis.

Mutations in a gene encoding an ABC transporter cause pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a heritable disorder characterized by calcification of elastic fibres in skin, arteries and retina that results in dermal lesions with associated laxity and loss of elasticity, arterial insufficiency and retinal haemorrhages leading to macular degeneration. PXE is usually found as a sporadic disorder, but examples of both autosomal recessive and autosomal dominant forms of PXE have been observed. Partial manifestations of the PXE phenotype have also been described in presumed carriers in PXE families. Linkage of both dominant and recessive forms of PXE to a 5-cM domain on chromosome 16p13.1 has been reported (refs 8,9). We have refined this locus to an 820-kb region containing 6 candidate genes. Here we report the exclusion of five of these genes and the identification of the first mutations responsible for the development of PXE in a gene encoding a protein associated with multidrug resistance (ABCC6).

The mouse lysyl oxidase-like 2 gene (mLOXL2) maps to chromosome 14 and is highly expressed in skin, lung and thymus

The predicted amino acid sequence derived from a mouse expressed sequence tag (EST) contig contained two domains that are highly conserved among members of the lysyl oxidase gene family: a copper binding-site with four histidines and a catalytic domain that includes a tryptophan residue. This new cDNA sequence showed the highest level of sequence homology with the human loxl2 cDNA and suggested that it encoded the mouse equivalent of hLOXL2. The mLOXL2 gene was mapped to chromosome 14 by radiation hybrid analysis. The mLOXL2 locus was tightly linked with a LOD score over 9 to the marker D14Mit32. The mLOXL2 gene is expressed as a 4-kb mRNA in almost all tissues analyzed, with highest levels of mRNA in skin, lung and thymus.

Novel trisaccharide fatty acid ester identified from the fruits of Morinda citrifolia (Noni)

Two known glycosides and a novel trisaccharide fatty acid ester were isolated from the n-butanol-soluble fraction of the fruits of Morinda citrifolia (noni). Structure determination was carried out by spectral techniques such as MS, IR, NMR, and 2D-NMR. The novel trisaccharide fatty acid ester was elucidated as 2, 6-di-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose. The known compounds were identified as rutin and asperulosidic acid.

Pseudoxanthoma elasticum maps to an 820-kb region of the p13.1 region of chromosome 16

We have performed linkage analysis on 21 families with pseudoxanthoma elasticum (PXE) using 10 polymorphic markers located on chromosome 16p13.1. The gene responsible for the PXE phenotype was localized to an 8-cM region of 16p13.1 between markers D16S500 and D16S3041 with a maximum lod score of 8.1 at a recombination fraction of 0.04 for marker D16S3017. The lack of any locus heterogeneity suggests that the major predisposing allele for the PXE phenotype is located in this region. Haplotype studies of a total of 36 PXE families identified several recombinations that further confined the PXE gene to a region (< 1 cM) between markers D16S3060 and D16S79. This PXE locus was identified within a single YAC clone and several overlapping BAC recombinants. From sequence analysis of these BAC recombinants, it is clear that the distance between markers D16S3060 and D16S79 is about 820 kb and contains a total of nine genes including three pseudogenes. We predict that mutations in one of the expressed genes in the locus will be responsible for the PXE phenotype in these families.

The LOXL2 gene encodes a new lysyl oxidase-like protein and is expressed at high levels in reproductive tissues

We have reported in this paper the complete cDNA sequence, gene structure, and tissue-specific expression of LOXL2, a new amine oxidase and a member of an emerging family of human lysyl oxidases. The predicted amino acid sequence, from several overlapping cDNA clones isolated from placenta and spleen cDNA libraries, shared extensive sequence homology with the conserved copper-binding and catalytic domains of both lysyl oxidase (LOX) and the lysyl oxidase-like (LOXL) protein. These conserved domains are encoded by five consecutive exons within the LOX, LOXL, and LOXL2 genes that also maintained exon-intron structure conservation. In contrast, six exons encoding the amino-terminal domains diverged both in sequence and structure. Exon 1 of the LOXL2 gene does not encode a signal sequence that is present in LOX and LOXL, suggesting a different processing and intracellular localization for this new protein. Expression of the LOXL2 gene was detected in almost all tissues with the highest steady state mRNA levels in the reproductive tissues, placenta, uterus and prostate. In situ hybridization identified placental syncytial and cytotrophoblasts responsible for the synthesis of LOXL2 mRNA and demonstrated a spatial and temporal expression pattern unique to the LOXL2 gene.

Coexpression of the lysyl oxidase-like gene (LOXL) and the gene encoding type III procollagen in induced liver fibrosis

We have isolated a mouse lysyl oxidase-like (LOXL) cDNA from a mouse embryo cDNA library and used this cDNA to measure changes in steady state levels of LOXL mRNA during the development of carbon tetrachloride-induced liver fibrosis in adult mice. These results revealed the coincident appearance of increased steady state levels of LOXL mRNA and type III procollagen mRNA early in the development of liver fibrosis. In contrast, steady state levels of lysyl oxidase mRNA increased throughout the onset of hepatic fibrosis and appeared in parallel with the increased steady state levels of pro-alphaI (I) collagen mRNA. These findings suggest that the LOXL protein (possibly an isoform of lysyl oxidase) is involved in the development of lysine-derived cross-links in collagenous substrates. Moreover, the substrate specificity of the LOXL protein may be different to that of lysyl oxidase and this difference may be collagen-type specific.

Lysyl oxidase-like protein localizes to sites of de novo fibrinogenesis in fibrosis and in the early stromal reaction of ductal breast carcinomas

Lysyl oxidase (LO) initiates the first step in the crosslinking of collagens and elastin and has also been shown to function as a tumor suppressor. The purpose of the present work was to determine whether the products of a newly described LO-like gene (LOXL) that encodes a close homolog of LO, the LO-like (LOL) protein, is associated with extracellular matrix remodeling during fibrotic disorders. Specific antibody against LOL identified proteins of approximately 30, 42, 52 and 68 kd in various cells and in bovine aorta. These proteins were immunochemically distinct from the recombinant LO expressed by fibroblasts and from the bovine aorta LO. The LO gene (LOX) and LOXL were transiently up-regulated at early stages of liver granuloma development in Schistosoma mansoni-infected mice, although the peak of LOL mRNA synthesis preceded that of LO. LOL protein and LO were colocalized at sites of fibrogenesis in human lung fibrosis and in the stromal reaction of bronchiolo-alveolar carcinomas and of in situ ductal breast tumors. In conclusion, the LOL protein was identified as a secreted protein and localized in the extracellular matrix in active fibrotic diseases and in the early stromal reaction of breast cancer.

Transcriptional and post-transcriptional control of lysyl oxidase expression in vascular smooth muscle cells: effects of TGF-beta 1 and serum deprivation

Transforming growth factor-beta 1 (TGF-beta 1) markedly reduced cell proliferation and elevated steady state lysyl oxidase (LO) mRNA 3-fold in neonatal rat aorta smooth muscle cells cultured in medium containing 10% fetal bovine serum. The increase in LO mRNA was prevented by the presence of cycloheximide, indicative of controlling events at the level of protein synthesis. The basal level of mRNA in cells proliferating in 10% fetal bovine serum in the absence of TGF-beta 1 was enhanced 7-fold upon decreasing growth by shifting to medium containing 0.5% serum. Changes in LO activity paralleled those in LO mRNA. Nuclear run-on assays revealed that the stimulation of expression in 0.5% serum involved increased gene transcription whereas that caused by TGF-beta 1 was mostly post-transcriptional in origin. LO mRNA was quite labile (t1/2 approximately 3 h) in 10% serum but was markedly stabilized (t1/2 > 12 h) by the presence of TGF-beta 1 in the 10% serum medium. LO mRNA was also considerably more stable under retarded growth conditions (0.5% serum) in the absence of TGF-beta 1. LO promoter activity in luciferase reporter constructs transfected into these cells was low and not significantly affected by the addition of TGF-beta 1 to the 10% serum medium but was markedly elevated by shifting from 10 to 0.5% serum in the absence of TGF-beta 1. Thus, LO expression is inversely correlated with cell proliferation, and is subject to control at transcriptional and post-transcriptional levels. TGF-beta 1 enhances LO expression in these cells by dramatically stabilizing LO mRNA.

Detection of elastin in the human fetal membranes: proposed molecular basis for elasticity

The human fetal membranes provide a sterile biomechanical container which adjust by growth to mid-pregnancy to the increase in fetal size, and by elasticity to the forceful movements of the fetus. The molecular basis for this elasticity is not known, yet reduced elasticity may lead to their premature rupture and preterm birth, a major problem in perinatal medicine. Classically, elastin confers the property of elastic recoil to elastic fibres which are assembled from a family of tropoelastin precursors. These are covalently cross-linked to form insoluble elastin by formation of desmosine and isodesmosine, catalysed by the enzyme lysyl oxidase. The amnion, chorion and decidua were shown by Northern analysis and RT-PCR to contain detectable levels of tropoelastin mRNA and the mRNA encoding lysyl oxidase. The proteins encoded by these mRNAs were also identified by Western blotting and immunolocalization. Further, insoluble elastin was extracted from the human fetal membranes and shown by comparison to elastin preparations from other elastic tissues to have a reasonable desmosine content. Finally, scanning electron microscopy confirmed the presence of multiple layers of an apparently very thin elastic system in this tissue. This biochemical and histopathologic study has demonstrated therefore that the human fetal membranes synthesize and deposit a novel elastic fibre. The presence of such an elastic system in these tissues provides, for the first time, a probable molecular basis for the elastic properties of this tissue.

An intron capture strategy used to identify and map a lysyl oxidase-like gene on chromosome 9 in the mouse

An intron capture strategy involving use of polymerase chain reaction was used to identify and map the mouse homologue of a human lysyl oxidase-like gene (LOXL). Oligonucleotides complementary to conserved domains within exons 4 and 5 of the human lysyl oxidase-like gene were used to amplify the corresponding segment from mouse genomic DNA. Sequencing of the resulting mouse DNA fragment of approximately 1 kb revealed that the exon sequences at the ends of the amplified fragment are highly homologous (90% nucleotide identity) to exons 4 and 5 of the human lysyl oxidase-like gene. An AluI restriction site polymorphism within intron 4 was used to map the mouse lysyl oxidase-like gene (Loxl) to mouse Chromosome 9 in a region that shares linkage conservation with human chromosome 15q24, to which the LOXL was recently mapped.

Functional analysis of the promoter and first intron of the human lysyl oxidase gene

Alterations in the synthesis and activity of lysyl oxidase occur concomitant with developmental changes in collagen and elastin deposition and with the pathogenesis of several acquired and heritable connective tissue disorders. To begin to unravel the mechanisms that control lysyloxidase gene expression, we have previously reported the complete exon-intron structure of the human lysyl oxidase gene. We have now sequenced this entire gene, including all six introns and 4 kb of DNA 5' of exon 1. Analysis of over 13 kb of intervening sequence and 5' flanking sequence revealed a concentration of conserved consensus sequence elements within the first intron and 1 kb immediately 5' of exon 1. Analysis of intron 1 and the 5' flanking domain, using recombinant plasmids containing the chloramphenicol acetyl transferase (CAT) reporter gene, identified functional DNA sequence elements within these non-coding domains responsible for inhibition and up-regulation of CAT activity in primary cultures of human skin fibroblasts, in smooth muscle cells, revertant cells derived from an osteosarcoma cell line and malignant c-Ha-ras-transformed osteosarcoma cells. DNA sequence elements within intron 1, in particular, resulted in a marked increase in CAT reporter activity in cultured fibroblasts, smooth muscle cells and osteosarcoma cells. In c-Ha-ras-transformed osteosarcoma cells, however, no such enhancer activity of intron 1 sequence was observed. Ras-transformed osteosarcoma cells exhibited reduced steady-state levels of lysyl oxidase mRNA that was primarily controlled through reduced transcription of the lysyl oxidase gene. The lack of any up-regulation of CAT activity in these ras-transformed cells by sequence elements within intron 1 suggests a complex interaction between cis-acting domains and trans-acting transcriptional factors in the 5' promoter domain and the first intron of the lysyl oxidase gene.

A new gene with sequence and structural similarity to the gene encoding human lysyl oxidase

We have isolated a number of recombinant clones from a human skin fibroblast cDNA library that contain extensive sequence homology to several coding domains within the human lysyl oxidase mRNA. Using one of these lysyl oxidase-like cDNAs, we obtained several overlapping genomic DNA recombinants. Restriction mapping and DNA sequence analysis revealed that the complete sequence of the lysyl oxidase-like mRNA was encoded by seven exons distributed throughout 25 kilobases of genomic DNA. Exons 2-6 encoded the region of greatest homology to lysyl oxidase. The size of these five exons, moreover, was exactly the same as the size of the corresponding exons within the lysyl oxidase gene. Northern blot analysis also revealed the concomitant appearance of lysyl oxidase and lysyl oxidase-like mRNA in several human tissues. It appears therefore that the genes encoding lysyl oxidase and a lysyl oxidase-like protein share a common evolutionary origin and may also be functionally related.

The size heterogeneity of human lysyl oxidase mRNA is due to alternate polyadenylation site and not alternate exon usage

We have isolated the entire gene coding for human lysyl oxidase. Coding and untranslated domains of human lysyl oxidase mRNA were found in 7 exons, distributed throughout approximately 14 kb of human genomic DNA. The appearance of exon sequences in lysyl oxidase mRNA in several human tissues was determined using a reverse transcriptase - PCR assay. In contrast to a previous report, this analysis has unambiguously shown that the size heterogeneity of lysyl oxidase mRNA was not due to alternate usage of any of the exons of the lysyl oxidase gene. Moreover, DNA sequence analysis of the entire 3.8 kb 3'-untranslated region (UTR) within exon 7 revealed multiple poly-adenylation sites which were shown to be differentially expressed in human skin fibroblasts. This differential usage of polyadenylation sites within the 3'-UTR explains the appearance of multiple lysyl oxidase mRNAs of different sizes.

A restriction fragment length polymorphism results in a nonconservative amino acid substitution encoded within the first exon of the human lysyl oxidase gene

A cDNA covering most of the coding sequence for human lysyl oxidase was used to screen, by Southern blot analysis, genomic DNA from circulating lymphocytes obtained from unrelated, apparently normal individuals. A heritable restriction fragment length polymorphism (RFLP) within a PstI restriction site was detected in 36% of individuals screened (a total of 72 chromosomes were analyzed). The major allele was represented as a 1.7-kb PstI restriction fragment. The minor allele was detected as 1.4 and 0.3kb restriction fragments. Lambda phage-DNA recombinants were isolated from a human lung fibroblast genomic DNA library using the human lysyl oxidase cDNA clone. DNA sequence analysis of several selected phage recombinants revealed that 83% of the coding sequence of lysyl oxidase was localized in four separate exons. Analysis of the coding sequence within exon 1, the most 5' exon within the lysyl oxidase gene, revealed that the PstI RFLP was due to a G-->A transition resulting in a nonconservative arginine to glutamine substitution proximal to a propeptide cleavage domain encoded by exon 1 of the lysyl oxidase gene.

Structure of the mouse lysyl oxidase gene

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.

Mechanism of action of tricyclic drugs on Escherichia coli and Yersinia enterocolitica plasmid maintenance and replication

Tricyclic medical compounds like many other non-antibiotics exhibit antimicrobial activities. Two chemically representative groups were tested in plasmid DNA transformation and replication to assign intracellular target sites responsible for the multiple effects in Escherichia coli and Yersinia enterocolitica cells. To analyse the mechanism of action at the molecular level, the effects of chlorpromazine, 7,8 dioxochlorpromazine, promethazine, methylene blue, imipramine, cannabidiolic acid and tetrahydrocannabidiolic acid were examined at several points in the course of transformation, in plasmid replication and on the topological state of plasmid DNA. Two possible target sites were identified, one of them involving membrane binding sites which participate in plasmid DNA replication. Drug binding at these sites interfered with the replicating plasmid DNA and membrane protein complex, preventing the proper processing of the replication that resulted in plasmid loss. The other in vivo and in vitro effect was observed on the topological state of plasmid DNA. Tricyclic drugs intefered with energy dependent gyrase activity and promoted the relaxation of plasmid DNA, causing disturbances in gene expression and in plasmid replication. The results give insight into the chemical structures connected with significant specific antimicrobial effects.

A developmentally regulated gvpABC operon is involved in the formation of gas vesicles in the cyanobacterium Calothrix 7601

In the filamentous cyanobacterium Calothrix PCC7601, gas-vesicle (GV) formation is restricted to specialized filaments, called hormogonia. The differentiation of these cells is controlled by environmental factors, such as light intensity and/or wavelength. The structural gene (gvpA) encoding a GV protein in this cyanobacterium has been previously cloned and sequenced. Two other genes, gvpB and gvpC have been found in the sequence downstream from gvpA. The gvpB gene corresponds to a second copy of gvpA, encoding an identical protein. Unlike the GV protein, the product of the gvpC gene is predominantly hydrophilic, as deduced from nucleotide sequence. Interestingly, the internal part of the gvpC gene is composed of four contiguous repeats, each containing 99 bp, forming highly homologous repeats in the deduced amino acid sequence. Another kind of periodicity has been detected inside the 99-bp repeats, suggesting that the gvpC gene might have evolved by amplification of a 33-bp-long primordial building block. The function of this gene remains to be elucidated. Finally, we have shown that the three genes, gvpA, gvpB, and gvpC, are organized in an operon that is exclusively expressed during GV formation in hormogonia.