Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 67-kDa protein identical to the enzymatically inactive spliced variant of beta-galactosidase is a major component of the non-integrin cell surface receptor expressed on fibroblasts, smooth muscle cells, chondroblasts, leukocytes, and certain cancer cell types. It recognizes several non-identical hydrophobic domains on elastin, laminin, and type IV collagen, provided they form a similar secondary conformation. The 67-kDa protein is not a transmembrane molecule, but immobilizes on the cell surface by an association with two other proteins, the 61-kDa neuraminidase and the 55-kDa 'protective protein'. The 67-kDa protein binds to matrix ligands in a calcium independent manner and only in the absence of galactosugars. Binding of these carbohydrate-bearing moieties causes such conformational changes of the 67-kDa protein that it loses the ability to bind its principal matrix ligands and separates from the cell surface. Galactosugars which inactivate this unique cell surface receptor may therefore modulate cell-matrix interactions, especially in such processes as SMC migration during vascular thickening, tumor cell metastasis, or tissue infiltration by the leukocytes. In elastin-producing cells, the 67-kDa protein associates with tropoelastin and serves as a molecular chaperone which facilitates its intracellular transport and extracellular assembly.
...
PMID:Biological roles of the non-integrin elastin/laminin receptor. 892 81

To identify regions involved in tissue specific regulation of transcription of the alpha1(VI) collagen chain, transgenic mice were generated carrying various portions of the gene's 5'-flanking sequence fused to the E. coli beta-galactosidase gene. Analysis of the transgene expression pattern by X-gal staining of embryos revealed that: (a) The proximal 0.6 kb of promoter sequence activated transcription in mesenchymal cells at sites of insertion of superficial muscular aponeurosis into the skin; tendons were also faintly positive. (b) The region between -4.0 and -5.4 kb from the transcription start site was required for activation of the transgene in nerves. It also drove expression in joints, in intervertebral disks, and in subepidermal and vibrissae mesenchyme. (c) The fragment comprised within -6.2 and -7.5 kb was necessary for high level transcription in skeletal muscle and meninges. Positive cells in muscle were mostly mononuclear and probably included connective tissue elements, although staining of myoblasts was not ruled out. This fragment also activated expression in joints, in intervertebral disks, and in subepidermal and vibrissae mesenchyme. (d) beta-Galactosidase staining in vibrissae induced by the sequences -4.0 to -5.4 and -6.2 to -7.5 was not coincident: with the latter sequence labeled nuclei were found mainly in the ventral and posterior quadrant, and, histologically, in the outer layers of mesenchyme surrounding and between the follicles, whereas with the former the remaining quadrants were positive and expressing cells were mostly in the inner layers of the dermal sheath. (e) Other tissues, notably lung, adrenal gland, digestive tract, which produce high amounts of collagen type VI, did not stain for beta-galactosidase. (f) Central nervous system and retina, in which the endogenous gene is inactive, expressed the lacZ transgene in most lines. The data suggest that transcription of alpha1(VI) in different tissues is regulated by distinct sequence elements in a modular arrangement, a mechanism which confers high flexibility in the temporal and spatial pattern of expression during development.
...
PMID:Distinct regions control transcriptional activation of the alpha1(VI) collagen promoter in different tissues of transgenic mice. 892 94

In order to develop gene therapy for Alport syndrome, we have examined the efficiency of adenovirus-mediated transfer of the beta-galactosidase gene into cultured cells and intact glomeruli in vitro, and developed an organ perfusion system for gene transfer into kidney ex vivo and in vivo. Human endothelial and mesangial cells, as well as isolated human glomeruli, were readily infected and exhibited expression of the reporter gene. Single or multiple injections of the virus solution into the renal artery of pig in vivo did not lead to significant gene transfer and expression of the reporter gene in kidney cells. To increase the exposure time of kidney cells to the virus we perfused kidneys ex vivo and in vivo for up to 12 and 2 h, respectively. The perfusion system consisted of a perfusate container, a peristaltic pump and an artificial membrane lung gassed with carbogen. Using this system, intense expression of the reporter gene could be achieved in up to about 85% of the glomeruli after perfusion of an explanted kidney ex vivo and about the same efficiency of gene transfer could be obtained in glomerular cells after 2-h perfusion in vivo. Some expression was observed in other vascular endothelial cells following the perfusion, but no expression was observed in cells of the Bowman's capsule or epithelial cells of the tubuli. The X chromosome-linked form of Alport syndrome is caused by defects in the gene for the type IV collagen of alpha5 chain, which is primarily expressed in the kidney in glomerular cells. The present results demonstrated that efficient gene transfer can be achieved into glomerular cells, a prerequisite for gene therapy of this disease. The organ perfusion method developed in this study might also be applicable for gene therapy of other diseases.
...
PMID:Adenovirus-mediated gene transfer into kidney glomeruli using an ex vivo and in vivo kidney perfusion system - first steps towards gene therapy of Alport syndrome. 892 8

A number of factors have been implicated in the regulation of tissue-specific collagen fibril diameter. Previous data suggest that assembly of heterotypic fibrils composed of two different fibrillar collagens represents a general mechanism regulating fibril diameter. Specifically, we hypothesize that type V collagen is required for the assembly of the small diameter fibrils observed in the cornea. To test this, we used a dominant-negative retroviral strategy to decrease the levels of type V collagen secreted by chicken corneal fibroblasts. The chicken alpha 1(V) collagen gene was cloned, and retroviral vectors that expressed a polycistronic mRNA encoding a truncated alpha 1(V) minigene and the reporter gene LacZ were constructed. The efficiency of viral infection was 30-40%, as determined by assaying beta-galactosidase activity. To assess the expression from the recombinant provirus, Northern analysis was performed and indicated that infected fibroblasts expressed high steady-state levels of retroviral mRNA. Infected cells synthesized the truncated alpha 1(V) protein, and this was detectable only intracellularly, in a distribution that colocalized with lysosomes. To assess endogenous alpha 1(V) protein levels, infected cell cultures were assayed, and these consistently demonstrated reductions relative to control virus-infected or uninfected cultures. Analyses of corneal fibril morphology demonstrated that the reduction in type V collagen resulted in the assembly of large-diameter fibrils with a broad size distribution, characteristics similar to fibrils produced in connective tissues with low type V concentrations. Immunoelectron microscopy demonstrated the amino-terminal domain of type V collagen was associated with the small-diameter fibrils, but not the large fibrils. These data indicate that type V collagen levels regulate corneal fibril diameter and that the reduction of type V collagen is sufficient to alter fibril assembly so that abnormally large-diameter fibrils are deposited into the matrix.
...
PMID:Reduction of type V collagen using a dominant-negative strategy alters the regulation of fibrillogenesis and results in the loss of corneal-specific fibril morphology. 894 62

1,25-Dihydroxyvitamin D3 (calcitriol) at 100 nmol/l elicited morphological differentiation and expression of collagen IV in mouse F9 embryonal carcinoma cells, and its effect was enhanced and accelerated by dibutyryl-cAMP (db-cAMP). The RAR beta 2 promoter was also activated, as evidenced by an increase in beta-galactosidase activity in an F9 reporter cell line with a stably integrated RAR beta 2-lacZ construct. All three effects were slower and less extensive with calcitriol than with retinoic acid, even in the presence of db-cAMP. Activation of the RAR beta 2 promoter by calcitriol required its TRE sequence, whereas db-cAMP required the CRE. TPA also activated the RAR beta 2 promoter, requiring a functional TRE. Thus, in the RAR beta 2 promoter the TRE sequence, whose function has so far been unidentified, mediates the effects of calcitriol and TPA. RAR beta 2 promoter activation by calcitriol was blocked by inhibitors of protein kinase C indicating that calcitriol elicits its effect via protein kinase C. Therefore, calcitriol induces differentiation of F9 mouse embryonal carcinoma cells at least in part by a pathway different from the classical one operative with retinoic acids.
...
PMID:Induction of mouse embryonal carcinoma cell differentiation and activation of the retinoic acid receptor beta 2 promoter by 1,25-dihydroxyvitamin D3. 896 Mar 71

A micrometastasis model was established using a rat differentiated prostatic adenocarcinoma, designated PLS30lZ, transfected with the lacZ gene encoding a bacterial beta-galactosidase. The morphology, tumorigenicity and metastatic ability of PLS30lZ were comparable to those of the parental cells. Micrometastatic foci could be specifically detected at the single cell level after X-Gal staining with a dissecting microscope. After intravenous injection, the number of X-Gal positive foci in the lung decreased progressively to a steady-state level (less than 1% of injected cells) by 4-7 days, while the size of persisting positive foci started to increase from 4 days after inoculation, as demonstrated by image analysis. X-Gal and BrdU double staining revealed that BrdU labeling indices of X-Gal-positive cells decreased transiently at the 2-day time point and increased again from 4 days after inoculation. Type IV collagen immunostaining showed the tumor cells to be surrounded by a basement membrane intravascularly at the time point when they started new growth. Electron microscopy confirmed that, 2 days post injection, most tumor cells were degenerative or dead, but on day 4, persisting tumor cells formed multicellular clumps in contact with the vascular basement membrane inside vessels. These results indicate that PLS30lZ cells begin to grow intravascularly depending upon the presence of a basement membrane before extravasation at the initial stage of micrometastasis formation.
...
PMID:Growth characteristics in the initial stage of micrometastasis formation by bacterial LacZ gene-tagged rat prostatic adenocarcinoma cells. 904 57

Proliferating, activated, hepatic stellate cells have a high level of collagen type I expression. Therefore, stellate cell proliferation is a critical step in hepatic fibrosis. Here we show that proliferation of activated primary rat stellate cells was blocked by elevation of cAMP with 8 Br-cAMP or isomethylbutyl xanthine, a phosphodiesterase inhibitor, and by stimulation of Ca2+ fluxes with the Ca2+ ionophore A-23187. Because phosphorylation of CREB on Ser133 is an important mediator of cAMP-protein kinase (PKA) and Ca2+-calmodulin kinase II (CAMK-II) activation, we tested whether CREB-PSer133 was essential for stellate cell quiescence. Nuclear extracts from quiescent, but not from activated, stellate cells contained CREB-PSer133. Moreover, the phosphorylation of CREB on Ser133 was stimulated in activated cells by inducing the activity of PKA or CAMK-II. In addition, coexpression of CREB and either a constitutively active PKA or a constitutively active CAMK-II inhibited the proliferation of activated stellate cells. In contrast, expression of CREB alone, PKA or CAMK-II alone, CREB-Ala 133 (which lacks the Ser133 phosphoacceptor) with PKA or CAMK-II, or CREB with inactive PKA or CAMK-II mutants did not affect stellate cell proliferation, suggesting that CREB-PSer133 is necessary for blocking the stellate cell cycle. Conversely, expression of a trans-dominant negative CREB-Ala 133 mutant (which competes with CREB/CREB-PSer133 for cognate DNA binding sites and presumably for protein interactions) induced a greater than fivefold entry into S-phase of quiescent stellate cells, compared with control cells expressing either beta-galactosidase or wt CREB, indicating that CREB-PSer133 may be indispensable for the quiescent stellate cell phenotype. This study suggests that PKA and CAMK-II play an essential role on stellate cell activation through the induction of CREB phosphorylation on Ser133, and provides potential approaches for the treatment of hepatic fibrogenesis in patients with chronic liver diseases.
...
PMID:Proliferation of hepatic stellate cells is inhibited by phosphorylation of CREB on serine 133. 907 42

The aim of this work was to develop a procedure for the lipid-mediated transfection of DNA into normal adult human hepatocytes in culture. Cells were plated in a serum-free culture medium at various cell densities, on plastic or collagen-coated dishes, both in the absence and in the presence of epidermal growth factor (EGF). The cells were incubated for various periods of time with mixtures of DNA-lipofectin or DNA-3 beta[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol (DC-chol) liposomes, and the efficiency of transfection was assessed by measuring the activity of reporter genes, beta-galactosidase or chloramphenicol acetyl-transferase (CAT). For comparison, similar experiments were carried out with human cell lines including HepG2, Caco-2, and WRL68. The efficiency of transfection (in percentage of cells) was not significantly different after transfection with lipofectin or DC-chol and comprised between 0.04 and 1.7% (extreme values) for different cultures. The efficiency of transfection decreased as the age or density of the culture increased and increased in cultures treated with EGF. Direct measurement of the rate of DNA synthesis suggested that the efficiency of transfection was related to the number of cells entering the S phase. Under the same conditions, the efficiency of transfection was one to two orders of magnitude greater in the three cell lines. A plasmid harboring 660 bp of the 5'-flanking region of CYP1A1 (containing two xenobiotic enhancer elements) fused upstream of the promoter of thymidine kinase and the CAT reporter gene was constructed. When this plasmid was transfected in human hepatocytes, CAT activity was induced as expected. We conclude that normal adult human hepatocytes can be transfected with exogenous DNA and that the transfected construct is regulated in the manner expected from in vivo studies.
...
PMID:Lipid-mediated transfection of normal adult human hepatocytes in primary culture. 912 68

A method has been developed for culturing cardiac myocytes in a collagen matrix to produce a coherently contracting 3-dimensional model heart tissue that allows direct measurement of isometric contractile force. Embryonic chick cardiomyocytes were mixed with collagen solution and allowed to gel between two Velcro-coated glass tubes. During culture, the cardiomyocytes formed spontaneously beating cardiac myocyte-populated matrices (CMPMs) anchored at opposite ends to the Velcro-covered tubes through which they could be attached to a force measuring system. Immunohistochemistry and electron microscopy revealed a highly organized tissue-like structure of alpha-actin and alpha-tropomyosin-positive cardiac myocytes exhibiting typical cross-striation, sarcomeric myofilaments, intercalated discs, desmosomes, and tight junctions. Force measurements of paced or unpaced CMPMs were performed in organ baths after 6-11 days of cultivation and were stable for up to 24 h. Force increased with frequency between 0.8 and 2.0 Hz (positive "staircase"), increasing rest length (Starling mechanism), and increasing extracellular calcium. The utility of this system as a test bed for genetic manipulation was demonstrated by infecting the CMPMs with a recombinant beta-galactosidase-carrying adenovirus. Transduction efficiency increased from about 5% (MOI 0.1) to about 50% (MOI 100). CMPMs display more physiological characteristics of intact heart tissue than monolayer cultures. This approach, simpler and faster than generation of transgenic animals, should allow functional consequences of genetic or pharmacological manipulation of cardiomyocytes in vitro to be studied under highly controlled conditions.
...
PMID:Three-dimensional reconstitution of embryonic cardiomyocytes in a collagen matrix: a new heart muscle model system. 924 Sep 69

There are no reported, convenient in vitro models for studying polarized functions in salivary epithelial cells. Accordingly, we examined three often-used salivary cell lines for their ability to form a polarized monolayer on permeable, collagen-coated polycarbonate filters. Only the SMIE line, derived from rat submandibular gland, had this ability. The SMIE cell monolayer exhibited junctional complexes, with a tight-junction-associated protein, ZO-1, localized to cell-cell contact areas. The Na+/K+-ATPase alpha1-subunit was detected predominantly in the basolateral membranes, while the Na+/H+ exchanger isoform 2 appeared primarily in the apical membranes. Using adenovirus-mediated cDNA transfer, SMIE cells were shown to be capable of routing marker proteins (beta-galactosidase +/- a nuclear targeting signal, alpha1-antitrypsin, aquaporin-1) to appropriate locations. Furthermore, this salivary cell monolayer provided a convenient tool for studying aquaporin-1-mediated, osmotically directed, transepithelial fluid movement in vitro. Thus, SMIE cells appear to be a useful experimental model with which to study some polarized functions in a salivary epithelial cell line.
...
PMID:A polarized salivary cell monolayer useful for studying transepithelial fluid movement in vitro. 942 93


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---