Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human pregnancy-specific glycoproteins (PSGs) are a family of closely related placental proteins that, together with the carcinoembryonic antigen members, comprise a subfamily within the immunoglobulin superfamily. To facilitate study of the control of PSG expression, we immortalized human placental cell lines with adenovirus-origin-minus (ori-)-simian virus-40 (SV40) recombinant viruses containing either wild-type or temperature-sensitive (ts) A mutants of SV40. Cells transformed with the SV40 tsA chimera (HP-A1 and HP-A2), but not the SV40 wild-type chimera (HP-W1), were temperature sensitive for transformation. All three cell lines expressed trophoblast-specific genes, including PSG and the alpha- and beta-subunits of hCG. Human CG alpha expression was greatly stimulated by (Bu)2cAMP in all three cell lines; shifting HP-A1 and HP-A2 cells to the nonpermissive temperature (39.5 C) further increased hCG alpha expression. At both 33 C (permissive temperature) and 39.5 C, the transformed placental cells expressed PSG mRNAs of 2.2 and 1.7 kilobases; expression was greatly stimulated by sodium butyrate. In the absence of an inducer, the three placental lines synthesized a PSG of 64 kilodaltons (kDa). In the presence of butyrate, they synthesized PSGs of 72, 64, and 54 kDa, similar to the placental PSGs. However, in placenta the predominant species is the 72-kDa product. At 39.5 C, butyrate selectively increased synthesis of the 72-kDa PSG in HP-A1 and HP-A2 cells. To characterize PSG promoter activity, we constructed chloramphenicol acetyltransferase (CAT) fusion genes containing -809 to -44 basepairs up-stream of the translational start site of the PSG6 gene. Using transient expression assays, we demonstrated that the -809/-44 region of the PSG6 gene contained cis-acting sequences that can direct CAT expression in human placental cells. Sodium butyrate, which stimulates PSG expression, greatly increased CAT activity, indicating that butyrate-induced PSG expression is regulated primarily at the level of gene transcription.
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PMID:Immortalization of virus-free human placental cells that express tissue-specific functions. 131 3

The pregnancy-specific glycoproteins (PSGs) of the human placenta and the carcinoembryonic antigens comprise a subfamily within the immunoglobulin superfamily. There may be as many as 20 different PSG genes which are predominantly expressed in the placenta. As an initial step toward understanding the control of PSG expression, we isolated and characterized two nearly identical PSG genes, PSG1 and PSG1-I. PSG1, which lacks exon 1 (5'/L), but contains exons 2 (L/N), 3 (A1), 4 (A2), and 5 (B2-C), encodes five previously identified type I transcripts, PSG1a, 1b, 1c, 1d, and 1e in a L/N-A1-A2-B2-C domain arrangement. PSG1-I, which contains a complete transcriptional unit consisting of exons 5'/L, L/N, A1, and B2-C, encodes type II PSG transcripts in a L/N-A1-B2-C domain arrangement. The predicted PSG1-I-encoded proteins share nearly complete sequence identity with the PSG1-encoded members, except the latter contain extra A domains. Amplification by polymerase chain reaction of placental or hydatidiform mole cDNA demonstrates that PSG1-I is a functional type II PSG gene. Using transient expression assays, we demonstrated that the -834/-34 region upstream of the translational start site of the PSG1-I gene contained the PSG promoter elements and the -834 to -456 region contained negative control elements. Sodium butyrate, an inducer of PSG synthesis, greatly stimulated expression of all PSG1-I-chloramphenicol acetyltransferase (CAT) fusion gene constructs. However, butyrate was at least 2-fold more effective in stimulating CAT activity of fusion genes containing upstream sequences (-834 to -576) than those containing proximal sequences (-456 to -172), suggesting two regions in the PSG1-I gene that mediate the butyrate response.
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PMID:Cloning and expression of genes encoding human pregnancy-specific glycoproteins. 164 21

The pregnancy-specific glycoproteins (PSGs) of the placenta, members of the immunoglobulin superfamily, are encoded by multiple linked genes located on chromosome 19. To study the control of PSG expression, we have immortalized differentiated human placental cells (HP-A1) temperature-sensitive for transformation by a recombinant adenovirus-(ori-)-SV40 tsA mutant virus. We now show that expression of the PSG gene in HP-A1 cells is temperature-sensitive. At the permissive temperature (33 degrees C), these cells expressed low levels of PSG mRNA and synthesized a 64-kDa PSG. Shifting HP-A1 cells to a nonpermissive temperature (39.5 degrees C) increased PSG mRNA expression and biosynthesis with preferential increase in the synthesis of a 54-kDa and a low level of a 72-kDa PSG. Moreover, PSG expression was greatly induced by 5-bromo-2'-deoxyuridine (BudR), which selectively increased synthesis of PSGs of 72 and 54 kDa. In the presence of BudR, HP-A1 synthesized PSGs of 72, 64, and 54 kDa, similar to the pattern seen with placental PSGs. Ribonuclease protection assays demonstrated that HP-A1 cells express the majority of PSG mRNAs and BudR stimulated expression of PSG1 and PSG1-like transcripts. Reverse transcription and polymerase chain reaction analysis using PSG gene-specific primers demonstrated that untreated HP-A1 cells expressed primarily PSG1, PSG2, PSG4, and PSG5 mRNAs. BudR stimulated the expression of all PSG transcripts except PSG4. Moreover, in transient expression assays, BudR increased chloramphenicol acetyltransferase (CAT) expression directed by PSG1-I, PSG4, PSG5, PSG6, and PSG11 promoter-CAT fusion genes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pregnancy-specific glycoprotein gene expression and the induction by 5-bromo-2'-deoxyuridine. 800 89

The pregnancy-specific glycoproteins (PSGs) of the human placenta are a group of proteins that together with the carcinoembryonic antigens comprise a subfamily within the immunoglobulin superfamily. To study the control of PSG expression, we isolated and characterized PSG genes and identified cis-acting DNA elements in the 5'-flanking gene regions essential for PSG expression. Two overlapping PSG cosmid clones, which contain two allelic variants of a PSG gene (PSG12 and PSG12 psi), were isolated from an unamplified library made from a single individual. Cosmid 1 contains exons 1 (5'/L) and 2 (L/N) of the PSG12 gene located downstream of a previously identified PSG1-I gene. Cosmid 6 contains a portion of the PSG1-I gene lacking exons 1 and 2 upstream of a complete PSG12 psi transcription unit. Sequence comparison indicates that exons 5'/L and L/N in PSG12 and PSG12 psi are 99% identical, except that the L/N exon in the PSG12 psi gene contains a stop codon. Both PSG12 and PSG12 psi transcripts were detected in the human placenta, indicating that both genes are actively transcribed. However, the PSG12 psi gene may represent an allelic pseudogene variant of the PSG12 gene, because all identified PSGs contain a functional N-domain. Primer extension analysis showed that the PSG12 gene starts at a cluster of sites located at -106 to -104 base pairs with respect to the translation start site. In transient transfection assays using a chloramphenicol acetyltransferase reporter gene, we demonstrated that the -835 to -34 DNA region upstream of the translation start site of PSG12 or PSG12 psi contained both positive and negative elements that control PSG expression. Deletion analysis showed that nucleotides -172 to -34 in the PSG12 gene could function as a promoter. Gel retardation analysis showed that protein factors in human placental cell extract formed four complexes (I, II, IIa, and III) with the PSG12(-172/-34) DNA. Site-directed mutagenesis that prevents protein factor binding to the PSG12 promoter resulted in a marked reduction in transcription activation, locating the core enhancers at nucleotides -148 to -141 and -60 to -55. Mutagenesis studies also showed that the ACAGC repeats at nucleotides -84 to -68 in the PSG12 5'-flanking are essential for expression of the PSG12 gene in human placental cells.
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PMID:Characterization of two allelic variants of a human pregnancy-specific glycoprotein gene. 834 32