Involvement of Smads in TGFβ1‐induced furin (<i>fur</i>) transcription
Bibliographic record
Abstract
Furin is recognized as being one of the main convertases of the cellular constitutive secretion pathway but the mechanisms regulating its expression are still unknown. We have previously demonstrated that TGFbeta1 up-regulates its own converting enzyme, furin, creating a novel activation/regulation cycle of potential importance in a variety of physiological and pathophysiological conditions. The fur (fes upstream region) gene is regulated via three alternative promoters; P1, P1A, and P1B. To gain insight into the molecular mechanism(s) underlying this up-regulation, we performed transient cell transfections with P1, P1A, and P1B promoter luciferase constructs. Transfection experiments in HepG2 cells revealed that fur P1 promoter is the strongest and the most sensitive to TGFbeta1 stimulation (5 ng/ml) (3.2-fold vs. 2.4-fold for P1A and 2.1-fold for P1B). Cotransfection with either a dominant negative mutant form of Smad2 [Smad2(3SA)] or a known Smad inhibitor [Smad7] inhibit constitutive and TGFbeta1-induced luciferase activity indicating the participation of endogenous Smads. Increased levels of TGFbeta1-induced transcriptional activation of the P1 promoter by overexpression of Smad2 and/or Smad4 is greatly reduced in the presence of Smad2(3SA) and completely inhibited by Smad7, suggesting the participation of endogenous Smad2/Smad4 complexes. Furthermore, the fork-head activin signal transducer (FAST-1), known to interact with Smad2/Smad4 complexes, is a potent stimulator of TGFbeta1-induced transactivation of the fur P1 promoter. Five prime-deletion analysis of this promoter identified the proximal region (between positions -8734 and -7925), as the nucleotide stretch that carries most of the transcriptional activation of fur P1 promoter by Smad2. Overall, the present data demonstrate that Smad2 and Smad4 possibly in complex with FAST-1 or other DNA binding partners participate in the constitutive and inducible transactivation of the fur P1 promoter. This represents the first detailed study of the transcriptional regulation of the fur gene.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".