Regulatory Interaction between Arylhydrocarbon Receptor and SIM1, Two Basic Helix-Loop-Helix PAS Proteins Involved in the Control of Food Intake
Bibliographic record
Abstract
The basic helix-loop-helix PAS (bHLH-PAS) transcription factors SIM1 and arylhydrocarbon receptor (AHR) are involved in the control of feeding behavior. Sim1 haploinsufficiency causes hyperphagia in mice and humans, most likely by perturbing the hypothalamus function. The administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a ligand of AHR, causes severe anorexia, which also appears to be of central origin. Both SIM1 and AHR require heterodimerization either with ARNT or ARNT2 to function. Here, we characterize the promoter for Sim1 and show that a consensus AHR-ARNT/2 binding site positively regulates its activity in the context of transfection experiments in Neuro-2A cells. A gel shift assay indicated that AHR-ARNT/2 can bind its putative site in the Sim1 promoter. Overexpression of Arnt, Arnt2, or Ahr increased the activity of a reporter construct containing the Sim1 promoter by 1.8-, 1.5-, and 2.2-fold, respectively, but failed to do so when the AHR-ARNT/2 binding site was mutated. Similarly, TCDD increased the activity of the reporter construct by 1.8-fold but not that of its mutated version. Finally, we found that TCDD increased Sim1 expression in Neuro-2A cells and in mouse kidney and hypothalamus by 4-, 3-, and 2-fold, respectively. We conclude that Sim1 expression is regulated by AHR-ARNT/2. This result raises the possibility that Sim1 mediates the effect of TCDD on feeding and points to a complex network of regulatory interactions between bHLH-PAS proteins.
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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".