POU Homeodomain Protein OCT1 Is Implicated in the Expression of the Caudal-related Homeobox Gene Cdx-2
Bibliographic record
Abstract
The caudal homeobox gene Cdx-2 is a transcriptional activator for approximately a dozen genes specifically expressed in pancreatic islets and intestinal cells. It is also involved in preventing the development of colorectal tumors. Studies using "knockout" approaches demonstrated that Cdx-2 is haplo-insufficient in certain tissues including the intestines but not the pancreatic islets. The mechanisms, especially transcription factors, which regulate Cdx-2 expression, are virtually unknown. We found previously that Cdx-2 expression could be autoregulated in a cell type-specific manner. In this study, we located an octamer (OCT) binding site within the mouse Cdx-2 gene promoter. This site, designated as Cdx-2(P)OCT, is involved in the expression of the Cdx-2 promoter. Both pancreatic and intestinal cell lines were found to express a number of POU (OCT binding) homeodomain proteins examined by electrophoretic mobility shift assay. However, it appears that Cdx-2(P)OCT interacts only with OCT1 in the nuclear extracts of the intestinal cell lines examined, although it interacts with OCT1 and at least two other POU proteins that are to be identified in the pancreatic InR1-G9 cell nuclear extract. Co-transfecting OCT1 cDNA but not five other POU gene cDNAs activates the Cdx-2 promoter in the pancreatic InR1-G9 and the intestinal Caco-2 cell lines. In contrast, Cdx-2(P)OCT cannot act as an enhancer element if it is fused to a thymidine kinase promoter. Furthermore, Cdx-2(P)OCT-thymidine kinase fusion promoters cannot be activated by OCT1 co-transfection. Cell type-specific expression, cell type-specific binding affinity of POU proteins to the cis-element Cdx-2(P)OCT, and the DNA content-dependent activation of Cdx-2 promoter via Cdx-2(P)OCT by OCT1 suggest that POU proteins play important and complicated roles in modulating Cdx-2 expression in cell type-specific manners.
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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) | 0.001 | 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".