Cloning and characterization of a new cAMP responsive element binding protein on rat angiotensinogen gene
Bibliographic record
Abstract
Angiotensinogen (ANG) is a single peptide glycoprotein that contains 452 amino acids in human (453 amino acids in rodents). ANG releases a 10-amino acids peptide known as angiotensin l (Ang I) from it's N-terminal when acted by renin, a acidic protease. Ang I can be fiirther converted into angiotensin II (Ang II) by angiotensin converting enzyme (ACE). Ang II is one of the most potent vasoconstrictors known. Ang II also acts on the brain to mcrease blood pressure. Ang II acts on the adrenal cortex to increase the secretion of aldosterone. The levels of ANG in plasma or local tissues diïectly contribute to the levels ofAng II. Therefore the studies of regulation ofANG gene expression is important to understand the molecular mechanisms of some related diseases, such as hypertension. Previous studies m which the transfection of the fusion genes that were generated with various lengths of 5'-flanking region of the rat ANG gene linked to a bacterial chloramphenicol acetyl transferase (CAT) gene as a reporter into mouse hepatoma (Hepa 1- 6) ceUs and opossum kidney (OK) cells, identified a putative cyclic AMP responsive element (CRE) in the rat ANG gene 5'-regulatory region (N-806/-779). Compared with palindromic CRE octamer (TGACGTCA), the putative CRE of the ANG gene (ANG-CRE) is almost identical except the last two bases were in reversed order (TGACGTAC). In the present study, we isolated a fuU-length cDNA of 1345 base pairs from mouse liver cDNA library, which encodes a nuclear DNA-binding protein consisting of 436 amino acids with an apparent molecular weight of 52 kilodalton (kDa). This protein binds to the ANG-CRE, and was designated as 52-kDa protein. Southwestern blot revealed that this 52 kDa protein was present in the following tissues, such as liver, kidney, testis, brain, but not in spleen. Analysis of the deduced amino acid sequence shows no apparent basic regionleucine zipper (bZIP) stmcture, indicatmg ANG-CREB is structurally distinct fi-om bZIP family members. The antiserum against 43-kDa-CREB or ATF-2 can not interact with this 52-kDa protein, further supporting that the 52-kDa protem is immunologically different fi-om the bZIP family. The 52-kDa protein may represent a new group of CRE-binding proteins. Competitive gel mobility shift assays and Southwestern blot analysis revealed that the ANG-CREB binds to ANG-CRE, and this bindmg is not displaceable by excess amounts of CREs fi-om somatostatin (SOM), phosphoenopymvate carboxyl kmase PEPCK), and tyrosine ammo transferase (TAT) genes in vitro. These data suggest that the 52-kDa protein binds specifically to ANG-CRE and may regulate the ANG gene expression. The biological function of the 52-kDa protein is not known at present. The primary data from transient gene transfection assays showed that this protein has represser activity on the ANG gene promoter when ANG gene was stimulated by isoproterenol, but showed no effect on the ANG basal level (without any stimulation). Further experiments will be needed to study the biological function of the 52-kDa protein.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".