In vitro transcription complementation assay with miniextracts of transiently transfected COS-1 cells.
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Cell Extracts↗
Biomedical subjects
O Georgiev
Publications and source records attributed to O Georgiev.
Different activation domains stimulate transcription from remote ('enhancer') and proximal ('promoter') positions.
We reported previously that the lymphocyte-derived octamer transcription factor 2A (Oct-2A or OTF-2A) activated both natural immunoglobulin promoters and synthetic promoters which contain the 'octamer' site, but was unable by itself to stimulate transcription from a remote enhancer position. Here we examine a larger set of transcription factors with respect to their proximal versus remote activation. Since a transcription factor may contain more than one activation domain, we have chosen to study the potential of individual activation domains in the context of fusion proteins that contain the DNA binding domain of GALA. We have identified at least two distinct functional classes of transcriptional activation domains. 'Proximal' activation domains, exemplified by glutamine-rich domains of Oct-1, Oct-2A and Sp1, stimulate transcription only from a position close to the TATA box, usually in response to a remote enhancer. 'General' activation domains, derived from VP16, GAL4, p65 (NF-chi B), TFE3, ITF-1 and ITF-2, can activate transcription from remote as well as proximal positions. These domains contain many acidic amino acids and/or other features such as clusters of serine and threonine. The proline-rich activation domains of AP-2 and CTF/NF1 may represent a third class with considerable promoter activity and low but significant enhancer activity. Furthermore, activation domains of both the acidic and glutamine-rich types seem to have a modular structure, since duplicated subdomains can substitute for the entire domain.
Amino Acid Sequence↗
[Changes in the lungs in progressive systemic scleroderma].
In 24 patients with progressive systemic scleroderma the respiratory disturbances, X-ray, scintigraphic and clinical deviations as well as the statistical correlations between them are described. The functional examination of respiration revealed lowered diffusion capacity, restrictive type of ventilatory failure and hypoxemia as the most frequent disturbances. The functional examination of respiration is correlated with the X-ray changes in the lungs in these patients.
Acid-Base Equilibrium↗
A novel expression assay to study transcriptional activators.
A novel assay to study transcriptional regulation in vivo designated trans-activation-dependent replication (TDR) assay is based on the modulation of a simian virus 40 (SV40)-derived replication system. A mixture of four plasmids (pPARA + pCIS + pTRANS + pREF) is co-transfected into vertebrate cells. After appropriate incubation, the replication of the pPARA plasmid (containing an SV40 origin of replication) is measured with a simple enzymatic test. We demonstrate that the level of replication is dependent on the differential trans-activation of the reporter pCIS (in which SV40 T-antigen is brought under control of the desired promoter) by the specific regulator protein encoded by the pTRANS plasmid. Three advantages make this assay a convenient tool for the systematic analysis of trans-activation in vivo: (1) remarkable sensitivity (higher than conventional assays); (2) rapid sample processing combined with a built-in standard (pREF-plasmid); (3) avoidance of expensive reagents such as freshly radiolabelled probes. We present the application of the TDR assay to the analysis of deletion mutants of the glucocorticoid receptor (GR) and other, GR-based chimeric trans-activators. The results demonstrate that the properties of protein domains are not always additive in a particular chimaera. Further application possibilities of the TDR assay are also discussed.
Animals↗
[Therapeutic drug monitoring of theophylline in the serum and saliva].
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Chromatography, Gas↗
[Dynamic changes in the functional respiratory indices in chronic obstructive lung disease].
The basic functional respiratory indices were followed up in 50 patients suffering from various forms of chronic obstructive pulmonary disease before and after treatment. A decrease of the dynamic indices followed up was found: inspiration indices--FEV 1% (forced expiratory volume), FVC% (forced vital capacity), FEV 1/FVC%, FEV 1/VC%; flow indices--MEF 25% (maximal expiratory flow), MEF 50% MEF 75%, PEF% (peak expiratory flow), MEF/FVC%, MMEF 25-70% (maximal mean expiratory flow). A decrease of vital capacity and of diffusion capacity was also found. The ratio RV/TLC% (residual volume/total lung capacity) was increased and a general hyperventilation was established. Moderate hypoxemia and lowered saturation by normocapnia and normal pH were also established. The control examinations after treatment showed improvement of all indices followed up.
Blood Gas Analysis↗
The conserved CAAGAAAGA spacer sequence is an essential element for the formation of 3' termini of the sea urchin H3 histone mRNA by RNA processing.
Analysis of cDNA sequences obtained from the small nuclear RNA U7 has previously suggested specific contacts, by base pairing, between the conserved stem-loop structure and CAAGAAAGA sequence of the histone pre-mRNA and the 5'-terminal sequence of the U7 RNA during RNA processing. In order to test some aspects of the model we have created a series of linker scan, deletion and insertion mutants of the 3' terminus of a sea urchin H3 histone gene and have injected mutant DNAs or in vitro synthesized precursors into frog oocyte nuclei for interpretation. We find that, in addition to the stem-loop structure of the mRNA, the CAAGAAAGA spacer transcript within the histone pre-mRNA is required absolutely for RNA processing, as predicted from our model. Spacer sequences immediately downstream of the CAAGAAAGA motif are not complementary to U7 RNA. Nevertheless, they are necessary for obtaining a maximal rate of RNA processing, as is the ACCA sequence coding for the 3' terminus of the mature mRNA. An increase of distance between the mRNA palindrome and the CAAGAAAGA by as little as six nucleotides abolishes all processing. It may, therefore, be useful to regard both these sequence motifs as part of one and the same RNA processing signal with narrowly defined topologies. Interestingly, U7 RNA-dependent 3' processing of histone pre-mRNA can occur in RNA injection experiments only when the in vitro synthesized pre-mRNA contains sequence extensions well beyond the region of sequence complementarities to the U7 RNA. In addition to directing 3' processing the terminal mRNA sequences may have a role in histone mRNA stabilization in the cytoplasmic compartment.
Animals↗