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

When a functional murine adenine phosphoribosyltransferase (aprt) gene linked to bovine papilloma virus (BPV) DNA is transfected into Aprt- L cells, the cells are rendered Aprt+ and the aprt gene persists as an episome. Cotransfection with two BPV vectors, one containing the 5' half of the aprt gene and the other the 3' half of the gene, that share about 300 bp of common sequence in intron 2, produces Aprt+ cells with functional aprt as an episome. Southern blot analysis of low molecular weight DNA derived from Hirt extracts revealed the regeneration of a diagnostic SmaI fragment, consistent with establishment of an episome with functional aprt that was reconstituted as a consequence of recombination. To establish cells with an episomal target for recombination, BPV vectors containing a G418 resistance marker and either the 5' half or 3' half of aprt were transfected into Aprt- L cells. Stably transfected cells, selected by their growth in G418, were in turn transfected with DNA containing the other half of the aprt gene. Following selection of Aprt+ cells, Southern blot and polymerase chain reaction (PCR) analysis of low molecular weight DNA confirmed the presence of a complete episomal aprt gene. The region of DNA shared by the episomal aprt fragment and the transfected aprt half was sequenced after PCR amplification of the reconstituted, episomal gene and was found to be wild type. The region of overlap that serves as the substrate for recombination lies entirely within an intron and can, therefore, tolerate nucleotide substitutions and deletions. The absence of such errors in the sequences examined is consistent with recombination events that are not error prone.
Mol Gen Genet 1992 Mar
PMID:Reconstitution of an episomal mouse aprt gene as a consequence of recombination. 131 48

Bovine aromatic L-amino acid decarboxylase (AADC) was expressed in a mouse cell line, using a bovine papilloma virus-derived expression vector containing the full coding region of bovine AADC. The recombinant bovine AADC was characterized biochemically and immunochemically and compared with the native bovine AADC. The specific activity of crude recombinant bovine AADC was 30-fold higher than that of crude native AADC. With regard to optimal pH, effects of pyridoxal phosphate concentration and Km for 3,4-dihydroxyphenylalanine as a substrate, both native and recombinant enzymes were essentially identical. Rabbit polyclonal antiserum directed against bovine adrenal AADC recognized on Western blot a single protein band (molecular mass = 55,000 Dalton) in both native and recombinant bovine AADC crude extracts. Furthermore, double immunodiffusion analysis showed a single precipitin line of confluence with both enzyme preparations, indicating immunological identity of native and recombinant bovine AADC. Northern blot analysis identified a single mRNA species (2.2 kb) from native and recombinant bovine AADC preparations. The recombinant bovine AADC has two charge isozymes corresponding to those of the native bovine enzyme, although their relative abundances are different between native and recombinant enzymes. Taken together, our results show that recombinant bovine AADC, expressed from bovine AADC cDNA in a mouse cell line is not only enzymatically active, but also shares many biochemical and immunochemical common features with native bovine AADC.
Brain Res Mol Brain Res 1992 Dec
PMID:Characterization of bovine aromatic L-amino acid decarboxylase expressed in a mouse cell line: comparison with native enzyme. 133 32

In normal epidermis, the expression of keratins 1 and 10 is associated with the loss of proliferative capacity and the onset of terminal differentiation. Keratins 1 (K1) and 10 (K10) are commonly expressed in the differentiating layer of benign tumors, but are lost during progression from the benign to the malignant state in skin carcinogenesis. Active gene constructs of mouse K1 and K10 were introduced into papilloma and carcinoma cell lines derived from keratinocytes to analyze the consequences of the expression of these keratins on the organization of the endogenous cytoskeletal network and on the mitotic activity of the recipient cells. Exogenous K1 integrated into the preexisting keratin K5/K14 network of both SLC-1 carcinoma and 308 papilloma cells. The formation of a recombinant cytoskeleton was more restricted for K10 than for K1 and appeared to be related to a requirement for cessation of cell division before K10 could integrate. The integration of exogenous K1 filaments into the endogenous keratin network was compatible with sustained proliferation of SLC-1 carcinoma cells in vitro. However, the exogenous gene was not expressed in tumor grafts in vivo. In contrast, stable K1 or K10 transfectants could not be selected in 308 cells, suggesting that benign tumor cells expressing suprabasal keratins cannot sustain proliferation.
Mol Carcinog 1992
PMID:Relationship between the expression of differentiation-specific keratins 1 and 10 and cell proliferation in epidermal tumors. 138 Feb 47

The induction of skin papillomas in mice can be divided into two different stages. Chemical initiation frequently elicits mutations in the Ha-ras gene, leading to the constitutive activation of ras. The second step, promotion, involves repetitive topical application of phorbol esters or wounding, leading to epidermal hyperproliferation and papilloma formation. We have found that overexpression of transforming growth factor alpha (TGF-alpha) in the basal epidermal layer of transgenic mice yielded papillomas directly upon wounding or 12-O-tetradecanoylphorbol-13-acetate treatment without the need for an initiator. Moreover, papillomas from TGF-alpha mice did not exhibit mutations in the Ha-ras gene. Interestingly, TGF-alpha acted synergistically with 12-O-tetradecanoylphorbol-13-acetate to enhance epidermal hyperproliferation. Our results demonstrate a central role for TGF-alpha overexpression in tumorigenesis and provide an important animal model for the study of skin tumorigenesis.
Mol Cell Biol 1992 Oct
PMID:Transgenic overexpression of transforming growth factor alpha bypasses the need for c-Ha-ras mutations in mouse skin tumorigenesis. 140 54

Okadaic acid (OA), a potent mouse skin tumor promoter and inhibitor of the protein phosphatases 1 and 2A, was investigated for its effects on the expression of tumor-associated early and secondary response genes in mouse keratinocytes. Adult mice were treated topically with 12.5 nmol of OA, and the steady-state levels of various gene transcripts in the skin were determined at different times after treatment. The nuclear proto-oncogenes c-fos and c-jun are referred to as early response genes because the classical tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) induces their expression to maximal levels within 2 h after treatment. OA induced the expression of c-fos 2-72 h after treatment, with two peaks at 6 and 48 h. The steady-state level of expression of c-jun was relatively high in untreated skin, and OA induced a slight increase in its expression from 12 to 48 h after treatment. Transin and plasminogen-activator (PA) urokinase, whose induced expression peaks at least 4 h after TPA treatment, are referred to as secondary response genes. OA induced their expression more slowly than TPA. In mouse papilloma cell line 308, OA induced higher and more sustained steady-state levels of c-jun and c-fos than an equimolar dose of TPA. Transin and PA-urokinase were induced to similar levels by TPA and OA in 308 cells; however, the induction of these genes by OA was slower than induction by TPA. The existence of different patterns of induced expression of early and secondary response genes by OA and TPA suggests that these tumor promoters affect gene expression in mouse keratinocytes through different pathways.
Mol Carcinog 1992
PMID:Okadaic acid induces the expression of both early and secondary response genes in mouse keratinocytes. 154 37

Bovine phenylethanolamine N-methyltransferase (PNMT) cDNA was inserted into a bovine papilloma virus-based expression vector and used to transfect a mouse C127 cell line. The resultant recombinant bovine PNMT was characterized biochemically and immunochemically. Recombinant bovine PNMT activity, like the native bovine enzyme, was enhanced by phosphate ion in a concentration-dependent manner. Their molecular weights were shown to be identical by Western blot analysis. Antibodies raised against native bovine adrenal PNMT equally immunoprecipitated the activity of the recombinant and native enzymes. In addition, double immunodiffusion analysis showed a single precipitin line of confluence with both enzyme preparations, indicating immunological identity of native and recombinant bovine PNMT. These antibodies immunostained the recombinant enzyme protein in transfected cells and in their neurite-like processes. In addition, in situ hybridization with the bovine PNMT cDNA probe resulted in a labelling pattern similar to the immunostaining. The recombinant bovine PNMT as the native bovine enzyme exist in multiple-charge forms, but only one form is predominant. Taken together, our results suggest that recombinant bovine PNMT, expressed from bovine PNMT cDNA in a mouse cell line is enzymatically active and shares many common features with native bovine adrenal PNMT.
Brain Res Mol Brain Res 1991 Jun
PMID:Characterization of recombinant bovine phenylethanolamine N-methyltransferase expressed in a mouse C127 cell line. 165 89

To investigate whether overexpression of the insulin receptor results in altered cell growth we used NIH 3T3 cells transfected with a bovine papilloma virus/insulin receptor cDNA construct (3T3/HIR). These cells expressed high numbers of insulin receptors (mean +/- sd, 631.0 +/- 16.7 ng receptors/10(6) cells). Insulin significantly stimulated the growth of 3T3/HIR cells maintained in serum-free medium. Moreover, in these cells, insulin induced marked phenotypic changes, including alterations in cell shape, loss of contact inhibition, and focal growth. In contrast to 3T3/HIR cells, insulin was without effect in either wild-type 3T3 cells (3T3/wt), 3T3 cells transfected with the neomycin resistance gene (3T3/NEO), or the bovine papilloma virus (3T3/BPV). To assess the presence of anchorage-independent growth, cells were seeded in soft agar and inspected for colony formation. 3T3/HIR cells showed absent or minimal colony growth in the absence of insulin. However, there was a dose-dependent insulin-stimulated increase in both colony size and number. Insulin-stimulated colony formation was specifically inhibited by an insulin antagonist, monoclonal antibody MA-10. In the presence of 100 nM insulin, about 3% of cells formed large colonies. Insulin neither stimulated growth nor induced colony formation in 3T3/wt cells or 3T3/NEO cells. Insulin also stimulated colony formation in CHO cells transfected with an insulin receptor cDNA construct. In conclusion, overexpression of normal insulin receptors induces a ligand-dependent transformed phenotype. This phenomenon may have clinical relevance by conferring a selective growth advantage to tumor cells with high numbers of insulin receptors.
Mol Endocrinol 1991 Mar
PMID:Overexpression of insulin receptors in fibroblast and ovary cells induces a ligand-mediated transformed phenotype. 165 97

DNA rotational mobility in a bovine papilloma virus (BPV)-based minichromosome, autonomously replicating in mouse cells, was studied using topoisomer analysis in temperature shift experiments. It was found that in live cells the average number of topological turns increased by six in the course of temperature shift through a range of 37 degrees C. This comprised approximately 85% of the total potential mobility of naked plasmid DNA. DNA rotation in isolated nuclei was found to be 3.5-4.0 turns per 37 degrees C in 100 mM NaCl - much higher than in all experiments with animal cells reported thus far. In low salt mobility was considerably lowered. Attempts to extract minichromosomes from nuclei allowed isolation of no more than 10% of minichromosomal DNA, with could indicate a very high proportion of transcriptionally active minichromosomes in the intracellular population. Growing cells in the presence of sodium butyrate resulted not only in an increase in the level of plasmid superhelicity and a decrease of its transcription (as we report in the accompanying publication) but also reduced rotational mobility of plasmid DNA threefold (from 6 to 2 turns per 37 degrees C). The decrease in DNA rotational mobility after butyrate treatment was also partially manifested in isolated nuclei (especially at lower ionic strength). To check whether histone acetylation is directly responsible for DNA immobilization, we performed in vitro acetylation of histones using acetyl adenylate. This resulted in severe DNA immobilization in experiments using both up and down temperature shifts.
Mol Gen Genet 1991 Dec
PMID:High rotational mobility of DNA in animal cells and its modulation by histone acetylation. 166 71

Gene expression during mouse keratinocyte carcinogenesis was examined in a clonal cell model. Tumor cells from three separate initiated cell lineages were compared with their nontumorigenic precursors and with the progenitor cell strain prior to treatment with 7,12-dimethylbenz[a]anthracene (DMBA). The steady-state levels of VL30 RNA in normal and papilloma cells were regulated by extracellular Ca2+ (which controls proliferation and differentiation in normal epidermal keratinocytes) and culture density. In contrast, steady-state levels of VL30 RNA were not regulated by these factors in the squamous cell carcinoma or the anaplastic carcinoma cells. VL30 expression was Ca2+ dependent in the initiated cell precursors within each tumor cell lineage, suggesting that the loss of response to extracellular Ca2+ was associated with the malignant conversion stage of carcinogenesis. No differences between normal and tumor cells were found in the cellular RNA levels of five additional proto-oncogenes. The mouse epidermal cell model should provide a means for direct assessment of a potential functional role of VL30 sequences in cancer development.
Mol Carcinog 1990
PMID:Altered levels of endogenous retrovirus-like sequence (VL30) RNA during mouse epidermal cell carcinogenesis. 169 77

The role of transforming growth factor-beta 1 (TGF-beta 1) in multisage carcinogenesis in mouse skin was assessed by studying its growth inhibitory effects on nontumorigenic and tumorigenic keratinocytes and by examining its mRNA expression in vitro and during epidermal hyperproliferation and multistage carcinogenesis. While growth of primary basal keratinocytes was inhibited by TGF-beta 1 in doses as low as 0.1 ng/mL, the immortal keratinocyte line MCA/3D ("putatively initiated" cells) responded to TGF-beta 1 with slightly reduced sensitivity, and the papilloma-producing keratinocyte line 308 was considerably less sensitive. In contrast, the squamous carcinoma cell line Carc B was completely nonresponsive, and two other tumorigenic cell lines (PDV and PDVC57) were sensitive to growth inhibition by TGF-beta 1. Steady-state levels of TGF-beta 1 mRNA were high in all the malignant cell lines and in line 308 papilloma cells, but low in primary basal cells and in the nontumorigenic keratinocyte lines V2, Reb1, and MCA/3D. Our in vivo studies showed that tumor promoters, but not mitogenic or weak hyperplasiogenic agents, were able to induce transient expression of TGF-beta 1 mRNA in mouse epidermis. A constitutive overexpression of TGF-beta 1 mRNA was observed in malignant carcinomas but not in the benign premalignant lesions, indicating that overexpression may be associated with malignant progression.
Mol Carcinog 1991
PMID:TGF-beta 1 and skin carcinogenesis: antiproliferative effect in vitro and TGF-beta 1 mRNA expression during epidermal hyperproliferation and multistage tumorigenesis. 171 Apr 62


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