Transcriptional Regulation of 2′,3′‐Cyclic Nucleotide 3′‐Phosphodiesterase Gene Expression by Cyclic AMP in C6 Cells
Bibliographic record
Abstract
It was recently shown that the two transcripts encoding the isoforms of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP1 and CNP2) are differentially regulated during the process of oligodendrocyte maturation. In oligodendrocyte precursors, only CNP2 mRNA is present, whereas in differentiating oligodendrocytes, both CNP1 and CNP2 mRNAs are expressed. This pattern of CNP expression is likely due to stage-specific transcriptional regulation of the two CNP promoters during the process of oligodendrocyte differentiation. Here, we report the influence of increased intracellular cyclic AMP (cAMP) levels on the transcription of both CNP1 and CNP2 mRNAs in rat C6 glioma cells. We found that the transcription of CNP1 mRNA was significantly increased in comparison with that of CNP2 mRNA in cells treated with cAMP analogues to elevate intracellular cAMP levels. This up-regulation of CNP1 expression (a) is due to an increase of transcription, (b) requires de novo protein synthesis, and (c) requires the activity of protein kinase A. These results are physiologically significant and support the idea that a cAMP-mediated pathway is part of the molecular mechanisms regulating the expression of CNP1 in oligodendrocytes. The regulation of CNP1 promoter activity by cAMP was then investigated in stably transfected C6 cell lines containing various deletions of the CNP promoter directing the bacterial chloramphenicol acetyltransferase gene. We showed that the sequence between nucleotides -126 and -102 was essential for the cAMP-dependent induction of CNP1 expression. Gel retardation analysis showed that two protein-DNA complexes are formed between this sequence and nuclear factors from C6 cells treated or not treated with cAMP. This suggests that the induction of CNP1 mRNA transcription is not mediated by changes in binding of nuclear factors that interact directly with the -126/-102 sequence. Sequence analysis of this region revealed the presence of a putative activator protein-2 (AP-2) binding site. It is interesting that mutagenesis of this region resulted in a significant reduction in transcriptional responses to cAMP, implying a possible role for the AP-2 factor in the expression of CNP1. In addition, we have shown that putative binding sites for activator protein-4 and nuclear factor-1 adjacent to the AP-2 site are required for efficient induction of CNP1 expression by cAMP. Taken together, our results show that the cAMP-dependent accumulation of CNP1 mRNA appears to depend on the synergistic interaction of several regulatory elements.
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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".