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

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

Mice and cells lacking the epidermal growth factor receptor (EGFR) were generated to examine its physiological role in vivo. Mutant fetuses are retarded in growth and die at mid-gestation in a 129/Sv genetic background, whereas in a 129/Sv x C57BL/6 cross some survive until birth and even to postnatal day 20 in a 129/Sv x C57BL/6 x MF1 background. Death in utero probably results from a defect in the spongiotrophoblast layer of the placenta. Newborn mutant mice have open eyes, rudimentary whiskers, immature lungs, and defects in the epidermis, correlating with the expression pattern of the EGFR as monitored by beta-galactosidase activity. These defects are probably cell-autonomous because chimeric mice generated with EGFR-/- embryonic stem cells contribute small amounts of mutant cells to some organs. These results indicate that the EGFR regulates epithelial proliferation and differentiation and that the genetic background influences the resulting phenotype.
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PMID:Strain-dependent epithelial defects in mice lacking the EGF receptor. 761 85

Cytochromes P450 are inserted into and anchored to the endoplasmic reticulum (ER) membrane by a hydrophobic signal sequence at the NH2 terminus. To determine whether the NH2-terminal sequence might also have an ER retention function, the NH2-terminal 29 amino acids of cytochrome P450 2C1, with and without an additional 29 amino acids containing an N-glycosylation site, were fused either to a soluble cytoplasmic protein, Escherichia coli beta-galactosidase, or to a secreted protein, E. coli alkaline phosphatase, and the hybrid proteins were expressed in COS1 cells. Subcellular fractionation indicated that both the beta-galactosidase and alkaline phosphatase hybrid proteins cosedimented with marker enzymes for ER membranes, and localization by immunofluorescent staining was consistent with an ER location. Hybrid proteins with the NH2-terminal glycosylation site were glycosylated in COS1 cells, and the carbohydrate moiety was sensitive to endoglycosidase H digestion, providing further evidence that the proteins were retained in the ER. In vitro studies of membrane insertion of the alkaline phosphatase hybrid indicated that fusion to alkaline phosphatase hybrid indicated that fusion to alkaline phosphatase did not alter the topological properties of the cytochrome P450 NH2-terminal sequence. In addition, alkaline phosphatase fused to the extracellular and transmembrane domains of epidermal growth factor receptor was transported to the plasma membrane in COS1 cells, which establishes that alkaline phosphatase as a cytoplasmic domain does not prevent transport from the ER. These observations indicate that the large cytoplasmic domain of cytochrome P450 is not required for retention in the ER and suggest that a specific sequence or structure within the NH2-terminal 29 amino acids functions as an ER retention signal.
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PMID:The amino-terminal 29 amino acids of cytochrome P450 2C1 are sufficient for retention in the endoplasmic reticulum. 836 Jan 66

Tissue-specific delivery of a variety of molecules has been a valuable technique for biological and medical research. Therefore, we have constructed a recombinant plasmid containing the coding regions for streptavidin core and mature human transforming growth factor-alpha (TGF-alpha). The recombinant plasmid has been expressed in Escherichia coli to produce a chimeric protein with both streptavidin and TGF-alpha activity. The streptavidin-TGF-alpha chimeric protein (ST-TGF-alpha) could efficiently transfer biotinylated beta-galactosidase into A431 cells via the epidermal growth factor receptor. More than 99% of the cells contained the enzyme transferred. Furthermore, ST-TGF-alpha complexed with biotinylated-glucose oxidase had a significant cytotoxic effect when incubated with A431 cells. These findings suggest that the ST-TGF-alpha chimeric protein could be used to deliver proteins of interest into target cells without the need for chemical linkage or genetic construction. Essentially, ST-TGF-alpha serves as a high-modular "molecular bridge" for the passage of a wide variety of effector molecules into target cells.
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PMID:Multi-drug delivery system using streptavidin-transforming growth factor-alpha chimeric protein. 892 14

An androgen-repressed human prostate cancer cell line, ARCaP, was established and characterized. This cell line was derived from the ascites fluid of a patient with advanced metastatic disease. In contrast to the behavior of androgen-dependent LNCaP and its androgen-independent C4-2 subline, androgen and estrogen suppress the growth of ARCaP cells in a dose-dependent manner in vivo and in vitro. ARCaP is tumorigenic and highly metastatic. It metastasizes to the lymph node, lung, pancreas, liver, kidney, and bone, and forms ascites fluid in athymic hosts. ARCaP cells express low levels of androgen receptor mRNA and prostate-specific antigen mRNA and protein. Immunohistochemical staining shows that ARCaP cells stain intensely for epidermal growth factor receptor, c-erb B2/neu, and c-erb B3. Staining is negative for chromogranin A and positive for bombesin, serotonin, neuron-specific enolase, and the c-met protooncogene (a hepatic growth factor/scatter factor receptor). ARCaP cells also secrete high levels of gelatinase A and B and some stromelysin, which suggests that this cell line may contain markers representing invasive adenocarcinoma with selective neuronendocrine phenotypes. Along with its repression of growth, androgen is also found to repress the expression of prostate-specific antigen in ARCaP cells as detected by a prostate-specific antigen promoter-beta-galactosidase reporter assay. Our results suggest that the androgen-repressed state may be central to prostate cancer progression and that advanced prostate cancer can progress from an androgen-independent to an androgen-repressed state.
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PMID:Androgen-repressed phenotype in human prostate cancer. 898 79

We have explored the use of adenovirus vector-mediated gene transfer to introduce foreign genes into osteoclasts, terminally differentiated cells responsible for bone resorption. A replication-deficient adenovirus vector that contains a reporter gene encoding beta-galactosidase efficiently infected human osteoclast-like cells (OCLs) derived from human giant cell tumors and mouse OCLs formed in vitro. We then constructed an adenovirus vector carrying human epidermal growth factor receptor (EGFR) cDNA (Ax1CAhEGFR) and introduced the EGFR gene into mouse OCLs. Clear induction of EGF receptor was detected in Ax1CAhEGFR-infected OCLs (EGFR-OCLs) by immunocytochemistry and immunoblotting, and EGF stimulation induced rapid tyrosine phosphorylation of several proteins including EGF receptor itself. Large vacuoles appeared in EGFR-OCLs in response to EGF treatment, and pit-forming activity by EGFR-OCLs was dose-dependently suppressed by recombinant human EGF. In addition, survival of EGFR-OCLs was prolonged by EGF. No expression of EGF receptor or effects of EGF were observed in noninfected OCLs or control vector-infected OCLs. These results suggest that adenoviral vectors are useful for modulating osteoclast function by introducing foreign genes into osteoclasts and that they will be a good means of gene therapy of metabolic bone diseases.
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PMID:Modulation of osteoclast function by adenovirus vector-induced epidermal growth factor receptor. 979 80

We previously developed the "immunogene" approach toward cancer gene therapy using epidermal growth factor receptor (EGFR)-mediated endocytosis. Here, we describe an improved immunogene system, in which the antigen-binding (Fab) fragments of the monoclonal antibody (Ab) B4G7 against the human EGFR were conjugated with poly-L-lysine to form a gene delivery vehicle (designated Fab "immunoporter"). Within 12 hours, the beta-galactosidase beta-gal) gene was transferred via the Fab immunoporter to virtually all of the nuclei of human squamous carcinoma A431 cells that overproduce the EGFR, and the beta-gal enzyme activity was detected within 24 hours and retained for more than 3 days. The beta-gal gene was not transferred into human and mouse cells that were deficient in EGFRs, but it was delivered if those mouse cells were transformed with human EGFR genes. Beta-gal gene transfer via the Fab immunoporter was inhibited by pretreatment with excess amounts of the Fab fragment. The transfer efficiency of the beta-gal gene to A431 cells via the Fab immunoporter was approximately 2%, which is as high as the lipofection method and 20- to 100-fold higher than the whole Ab immunoporter. The transfer of the herpes simplex virus thymidine kinase gene into A431 tumor cells as a form of the thymidine kinase/Fab immunogene was successful, and subsequent treatment with ganciclovir induced remarkable suicide effects which conferred 1000-fold higher drug sensitivity. Thus, the Fab immunogene was substantially improved with regard to the whole Ab immunogene and could be used as a potent gene transfer vehicle for the in vivo targeting of EGFR-hyperproducing tumor cells.
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PMID:Receptor-mediated gene delivery using the Fab fragments of anti-epidermal growth factor receptor antibodies: improved immunogene approach. 991 90

This article describes the step-wise approach undertaken to select a serum-free medium (SFM) for the efficient production of a recombinant adenoviral vectors expressing beta-galactosidase (Ad5 CMV-LacZ), in the complementing human embryonic kidney 293S cells. In the first step, a 293S-derived transfectoma, secreting a soluble epidermal growth factor receptor sEGFr (D2-22), was used to estimate the potential of selected serum-free formulations to support the production of a recombinant protein as compared to serum-containing medium. Assays showed that only one among six commercial serum-free formulations could support both sEGFr production and cell growth in static or suspension culture. In commercially available calcium-containing serum-free formulations, the cell aggregates reached up to 3 mm in diameter. In the second step, 293S cells were gradually adapted to a low-calcium version of the selected medium (LC-SFM). Cells were cloned, then screened according to their ability to grow at a rate and an extent comparable to parental cells in serum-containing medium (standard) as single cells or small aggregates. The 293SF-3F6 clone, first adapted to and then cloned in the selected serum-free medium, was selected for further experiments. Bioreactor run performed with the 293SF-3F6 clone showed similar growth curve as in the shake-flask controls. In the final step, the recombinant viral vector productivity of the 293S cells and the 293SF-3F6 clone was tested. The 293SF-3F6 cells infected by Ad5 CMV-LacZ in 3 L-scale bioreactor maintained the specific productivities of both beta-galactosidase and adenoviral vector equivalent to the shake-flask controls in suspension culture. Results from this study clearly demonstrate that the 293SF-3F6 cell line thus selected may be used either for establishing stable transfected cell line or for the production of adenoviral vectors required for gene therapy studies.
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PMID:Serum-free production of recombinant proteins and adenoviral vectors by 293SF-3F6 cells. 1009 73

Cytotoxic strategies which are directed to tumor-associated antigens might be most beneficial for cancer patients with minimal tumor load such as in an adjuvant setting after initial therapy. We have recently described a highly potent single chain antibody-toxin, scFv(14E1)-ETA, which consists of the variable domains of the antibody 14E1 genetically fused to a truncated form of Pseudomonas exotoxin A. ScFv(14E1)-ETA specifically recognizes the human epidermal growth factor receptor (EGFR) and the oncogenically activated receptor variant EGFRvIII, which have been implicated in the development of various human malignancies. Here we have investigated the antimetastatic activity of bacterially expressed scFv(14E1)-ETA and its disulfide-stabilized derivative ds-scFv(14E1)-ETA in a novel model for disseminated disease which is based on murine renal carcinoma cells subsequently transfected with the E. coli beta-galactosidase gene, and human full-length or variant EGFR cDNAs. Intravenous injection of these Renca-lacZ/EGFR and Renca-lacZ/EGFRvIII cells in syngenic Balb/c mice led to the formation of pulmonary metastases which were readily detectable upon excision of the lungs and X-gal staining. Systemic treatment of mice with scFv(14E1)-ETA resulted in the complete suppression of Renca-lacZ/EGFRvIII metastasis formation and drastically reduced the number of pulmonary Renca-lacZ/EGFR tumor nodules. The ds-scFv(14E1)-ETA derivative where the antibody variable regions are connected by an artificial disulfide bond displayed improved thermal stability at physiological temperature but due to reduced cytotoxic activity was less potent than the original scFv(14E1)-ETA in metastasis suppression.
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PMID:Suppression of metastasis formation by a recombinant single chain antibody-toxin targeted to full-length and oncogenic variant EGF receptors. 1020 32

Transforming growth factor beta (TGF-beta) plays important roles in the regulation of proliferation, differentiation, apoptosis, and carcinogenesis. To identify genes responsible for maintaining the phenotype induced by TGF-beta, we performed a retrovirus-mediated gene trap screening designed to isolate TGF-beta-responsive genes in human lung carcinoma cell line A549. After screening 249 trap lines, 21 were found to express the reporter beta-galactosidase gene in a TGF-beta-responsive manner. Interestingly, in large proportions of these trap lines, the reporter gene was responsive also to phorbol ester and was suppressed by gamma interferon. Fragments of all these trapped genes were recovered by 5'- and 3'-rapid amplification of cDNA ends (RACE), and in 15 out of 21 cases (71%), the TGF-beta responsiveness of the endogenous genes was confirmed by RNA blot hybridization. In at least five cases, the TGF-beta-induced upregulation was found to be cycloheximide resistant, suggesting the roles of the genes in the TGF-beta-induced primary responses. Sequence analyses revealed that 43% (9 of 21) of the trapped genes were novel and that the remainder included genes previously reported to be upregulated by TGF-beta, such as epidermal growth factor receptor and beta1 integrin, documenting the validity of this approach. Other known genes include the ones encoding the proteins associated with cell proliferation (ribosomal proteins S15a, hNRP/NAP-1, and lipocortin II), focal adhesions (paxillin), and transcriptional regulation (thyroid hormone receptor activator molecule 1 [TRAM-1]).
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PMID:Identification of a series of transforming growth factor beta-responsive genes by retrovirus-mediated gene trap screening. 1075 10

In recent years gene therapy has evolved as a new treatment for brain tumors, where genetically engineered cells can be used to deliver specific substances to target cells. However, clinical success has been limited due to insufficient gene transfer, lack of prolonged gene expression, and immunorejection of producer cells. These obstacles may be overcome by encapsulating producer cells into immunoisolating substances such as alginate. This may provide a stable in situ delivery system of specific proteins, which can interfere with tumor growth and differentiation. This article represents a fundamental study describing the in vitro and the in vivo behavior of alginate-encapsulated producer cells. The viability and cell cycle distribution of encapsulated NIH 3T3 cells was studied by confocal laser scanning microscopy (CLSM) and by flow cytometry. The CLSM study showed a high viability of the encapsulated NIH 3T3 cells during 9 weeks in culture. The flow cytometric analysis revealed a change in cellular ploidy after 1 week in culture, with normalization in ploidy after 3 and 9 weeks. The production of the bacterial E. coli beta-galactosidase in alginate-encapsulated BT4CnVlacZ cells was studied by x-gal staining, and the cells expressed prolonged beta-galactosidase activity. H528 hybridoma cells producing monoclonal antibodies (mAbs) against the human epidermal growth factor receptor (EGFR) were encapsulated in alginate, and the mAb release was determined. The release of mAbs stabilized around 400 ng/ml/h after 12 days in vitro. To actually demonstrate that alginate-encapsulated H528 cells potentially inhibit a heterogeneous glioma cell population, cell migration from human GaMg glioma spheroids was studied during stimulation with EGF in the presence of encapsulated H528 cells. The migration in vitro was totally inhibited in the presence of H528 encapsulated cells. Alginate beads with H528 cells were also implanted into rat brains, and after 9 weeks the distribution of mAbs within the brain was studied by immunohistochemistry. It is shown that the alginate entrapped H528 cells produce mAbs inside the brain for prolonged periods and that the mAbs are distributed within all CSF compartments. Encapsulated producer cells represent a potential delivery system for specific proteins to brain tumors. Different producer cells may be encapsulated in alginate to target phenotypic features and microenvironmental factors, which may influence the progressive growth of brain tumors.
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PMID:Alginate-encapsulated producer cells: a potential new approach for the treatment of malignant brain tumors. 1120 64


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