Functional significance of Sp1, Sp2, and Sp3 transcription factors in regulation of the murine CTP:phosphocholine cytidylyltransferase α promoter
Bibliographic record
Abstract
The transcription factor Sp1 has been implicated in regulation of the expression of the murine CTP:phosphocholine cytidylyltransferase alpha (CTalpha) gene, Ctpct (M. Bakovic, K. Waite, W. Tang, I. Tabas, and D. E. Vance. 1999. Biochim. Biophys. Acta. 1438: 147;-165). We have utilized transient transfections, mutation analysis, electromobility gel-shifts, and immunoblot analysis to test the hypothesis that expression of the CTalpha gene is controlled in part by the binding of three trans-acting nuclear factors, Sp1, Sp2, and Sp3. Sp1 and Sp3 activate CTalpha gene transcription through sequence specific binding within three promoter domains. In Sp1-mediated transcription, Sp3 acts as an activator in a dose-dependent manner and vice versa. Sp2 represses Sp1- and Sp3-driven transcription in Drosophila SL2 cells, but stimulates transcription in C3H10T1/2 mammalian cells. Our results suggest that the predominant action of Sp proteins is a direct function of local organization of three cis-acting elements in the regions A (-31/-9), B (-88/-50), and C (-148/-128). The ability of distal C (-148/-128) and proximal A (-31/-9) regions to activate or repress transcription depends upon the cellular background. The multiple binding elements at position B (-88/-50) confer a positive regulation independent of the cell context. However, the effectiveness of Sp proteins at this site is strongly governed by neighboring sites A and C. The results suggest that the level of expression of the CTalpha gene will depend on the cell type, the availability of Sp proteins, and the structure and organization of three cis-acting elements.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".