Differential Expression of Activator Protein-1 Transcription Factors in Pregnant Rat Myometrium1
Bibliographic record
Abstract
While the AP-1 (activator protein-1) genes c-fos and c-jun have been implicated in the expression of myometrial genes associated with the onset of labor, there are no data concerning the role of other members of this family of transcription factors. To address this issue, we defined the expression and hormonal regulation of AP-1 genes in the rat myometrium during pregnancy and labor. Tissue was collected on Days 12, 15, 17, 19, 21, 22, and 23 (labor) and 1 day postpartum. Expression of c-fos, fosB, fra-1, fra-2, and junB was low during early gestation, with a 5- to 10-fold increase on Day 23 during labor, and returned to low levels 1 day postpartum. In contrast, the levels of c-jun and junD remained relatively constant throughout gestation. Administration of progesterone (P4; 16 mg/kg s.c./day) beginning on Day 20 (to maintain elevated plasma P4 levels) prevented the onset of labor and blocked the expected rise in c-fos, fosB, fra-1, fra-2, and junB expression on Day 23. In contrast, administration of the progesterone receptor antagonist RU486 (10 mg/kg s.c.) on Day 19 induced preterm labor and a premature increase in mRNA levels of c-fos, fra-1, fra-2, and junB. In unilaterally pregnant rats, stretch imposed by the growing fetus was found to increase the expression of c-fos, fosB, fra-1, fra-2, and junB only in the gravid horn on the day of labor. These data raise the possibility that AP-1 transcription factors integrate endocrine and mechanical signals, leading to myometrial gene expression required for uterine remodeling and the initiation of labor.
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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 | 0.001 | 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) | 0.001 | 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 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".