Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.2.1.7 (BAL)
 1,977 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deletion analysis of the 5' flank of the Chinese hamster dihydrofolate reductase (dhfr) gene reveals a promoter region starting 48 base pairs upstream of the major transcriptional start site. A dhfr minigene containing approximately 900 base pairs of 5' flank and one small intron was used as a wild-type standard. Seven deletions were created with BAL-31. Promoter activity was measured in three ways: 1) transient expression of the dhfr gene; 2) frequence of transfection of dhfr- Chinese hamster cells to a dhfr+ phenotype; and 3) RNase protection analysis of dhfr transcripts in pooled populations of permanently transfected cells. The transient expression assay was developed in this work for the rapid analysis of dhfr promoter mutants; this assay could be of general use for analyzing constructs carrying dhfr as a reporter gene. Two of the deletions define a requirement for part or all of the sequence GGGCGT located 48 base pairs upstream of the major transcriptional start site. This site has been shown to bind transcription factor Sp1 in the mouse dhfr gene. The function of the major promoter is independent of the function of the minor promoter. These minigene constructs also contain cryptic promoters located upstream of the natural start sites, probably in the plasmid vector. Transcripts originating from these upstream sites are inefficiently spliced, but do result in messenger RNA molecules that are translated into active dihydrofolate reductase.
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PMID:Deletion analysis of the Chinese hamster dihydrofolate reductase gene promoter. 318 92

To detect nuclear proteins that might be involved in induction of cellular mitogenesis, we examined the effect of various mitogens on early changes in synthesis of nuclear proteins in murine B lymphocytes. Using two-dimensional gel electrophoresis, we found that activation of B cells by mitogens (anti-immunoglobulin antibody, lipopolysaccharide, phorbol 12-myristate 13-acetate (PMA)/A23187) was associated with a rapid and prominent (5-20-fold) increase in the synthesis of a 40-kDa/pI 5.0 nuclear protein, here termed numatrin. Numatrin was found to be absent from the cytosol (soluble fraction) of resting as well as activated B cells and was markedly resistant to DNase/RNase digestion and 2 N NaCl extraction, indicating that this protein is tightly bound to the nuclear matrix. Kinetic studies showed that the increase in synthesis of numatrin was detected 60-120 min following mitogen activation, reached a peak at 16 h, and declined to almost control level by 48 h, correlating with the peak of cellular DNA synthesis. The increase in synthesis of numatrin in normal B cells was found to be associated exclusively with cellular commitment for mitogenesis because activation of B cells by stimuli such as B cell stimulating factor 1, PMA alone, and calcium ionophore A23187, which do not stimulate an increase in DNA synthesis, also failed to induce an increase in the synthesis of numatrin. Inhibition of anti-Ig-induced proliferation (by PMA pretreatment) was associated with a 63% inhibition in the synthesis of numatrin. Addition of 8-mercaptoguanosine to these PMA-treated cells was associated with restoration of the increase in synthesis of numatrin, concomitant with induction of proliferation. Elevated synthesis of numatrin was also detected in the malignant B lymphoma cells: Raji, BAL-17, and WEHI-231. Taken collectively, these results suggest that numatrin, a tightly bound nuclear matrix protein, is a growth-regulated protein which might have an important role in regulation of cellular mitogenesis in normal and malignant B lymphocytes.
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PMID:"Numatrin," a nuclear matrix protein associated with induction of proliferation in B lymphocytes. 330 55

The +1 site for initiation of inducible chloramphenicol acetyl transferase (CAT) mRNA encoded by plasmid pC194 was determined experimentally by using [alpha-32P]ATP-labeled runoff transcripts partially digested with T1 RNase. By partial digestion of the in vitro transcripts with S1, T1, and cobra venom nucleases as probes of mRNA conformation, single- and double-stranded regions, respectively, were also identified. Thus, a prominent inverted complementary repeat sequence was demonstrated spanning the +14 to +50 positions, which contain the complementary sequences CCUCC and GGAGG (the Shine and Dalgarno sequence for synthesis of CAT) symmetrically apposed and paired as part of a perfect 12-base-pair inverted complementary repeat sequence (-19.5 kcal [ca. -81.7 kJ] per mol). The CAT mRNA was stable to digestion by T1 RNase at the four guanosine residues in the Shine and Dalgarno sequence GGAGG , even at 60 degrees C, suggesting that nascent CAT mRNA allows ribosomes to initiate protein synthesis inefficiently and that induction involves post-transcriptional unmasking of the Shine and Dalgarno sequence. Consistent with this model of regulation, we found that cells carrying pC194 , induced with chloramphenicol, contain about the same concentration of pulse-labeled CAT-specific RNA as do uninduced cells. Induction of CAT synthesis by the non- acetylatable chloramphenicol analog fluorothiamphenicol was tested by using minicells of Bacillus subtilis carrying pC194 as well as minicells containing the cloned pC194 derivatives in which parts of the CAT structural gene were deleted in vitro with BAL 31 exonuclease. Optimal induction of both full-length (active) and deleted (inactive) CAT required similar concentrations of fluorothiamphenicol, whereas induction by chloramphenicol required a higher concentration for the wild-type full-length (active) CAT than for the (inactive) deleted CAT. Because synthesis of deleted CAT was inducible, we infer that CAT plays no direct role in regulating its own synthesis.
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PMID:Post-transcriptional regulation of chloramphenicol acetyl transferase. 620 72

Surfactant protein D (SP-D) appears to play an important role in regulating local pulmonary inflammatory responses to pathogens. There is also in vitro evidence that SP-D may suppress local T cell responses. However, the role of SP-D in regulating T cell responses directly in the lung has not been previously evaluated in vivo. SP-D(-)(/-) mice demonstrate peribronchial and perivascular accumulations of lymphocytes. Therefore, we investigated the functional status and abundance of intrapulmonary lymphocytes in SP-D(-)(/-) mice. By morphometric analysis, SP-D(-)(/-) mice demonstrated increased numbers of airway- and vessel-associated lymphocytes without increases in interstitial lymphocytes. There was increased proliferative activity of lymphocytes isolated by enzymatic disassociation of minced lung. Flow cytometry was used to determine the number and functional activation status of intrapulmonary CD4(+) and CD8(+) T cells, as well as B cells and NK cells. Cytokine expression patterns in lung tissues were evaluated using RNase protection assays, reverse transcriptase/polymerase chain reaction, and enzyme-linked immunosorbent assay. There was marked T cell activation in the lungs of SP-D(-)(/-) mice, as reflected by an increased percentage of both CD4(+) and CD8(+) T cells expressing CD69 and CD25. BAL CD4 lymphocytes were increased and the fraction expressing CD69 was also increased. Although there were increases in BAL CD8 lymphocytes, apparent increases in CD69-positive CD8 lymphocytes did not reach statistical significance. In contrast, splenic T cells were not activated in SPD(-)(/-) mice. Of the proinflammatory cytokines evaluated, only interleukin (IL)-12 and IL-6 expression were consistently upregulated in the lungs of SPD(-)(/-) mice. Increased IL-2 expression was apparent but did not reach statistical significance. We conclude that the lack of local pulmonary production of SP-D leads to a state of persistent T cell activation, possibly in response to exogenous antigens. This study therefore provides further evidence of the important local immunoregulatory role of SP-D in vivo.
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PMID:Lymphocyte activation in the lungs of SP-D null mice. 1209 Dec 42