Nuclear localization and binding affinity of STAT5b for the alpha(2)-macroglobulin gene promoter during rat liver development and the acute-phase response.
Bibliographic record
Abstract
Expression of the rat alpha(2)-macroglobulin (MG) gene undergoes dynamic changes throughout an individual's life and during the acute-phase (AP) response. Details of the participation of the STAT family of transcription factors in its control remain incompletely understood. Here we examined the involvement of STAT5b in MG gene expression during development and the AP response. Immuno-blot analysis revealed the highest nuclear level of STAT5b in the fetus and during postnatal development, whereas in the adult it decreased. Stimulation of MG expression during the AP response was accompanied by a decrease in STAT5b. Examination of STAT5b localization revealed that the relative concentrations of STAT5b were higher in the nuclear matrix than in the nuclear extract. Affinity chromatography with the extended promoter region of the MG gene (-825/+12), followed by immuno-blot analysis, revealed dynamic changes in STAT5b binding. The highest concentration of the promoter-binding form of STAT5b was observed in the fetus. As postnatal development progressed, the level of promoter-bound STAT5b decreased and in the adult liver it was the lowest. Stimulation of MG gene expression during the AP response in both the fetus and adult was accompanied by significantly decreased STAT5b binding to the MG promoter. The AP response was accompanied by lower levels of STAT5b serine and tyrosine phosphorylation in both fetus and adult. In the nuclear matrix derived from adult tissues, tyrosine phosphorylated species were completely absent. We conclude that developmental-stage differences in the mechanisms that determine STAT5b nuclear localization contribute to its activity in vivo.
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".