Molecular Characterization, Tissue-Specific Expression, and Regulation of Melanocortin 2 Receptor in Rainbow Trout
Bibliographic record
Abstract
ACTH, the primary secretagogue for corticosteroid biosynthesis, binds to melanocortin 2 receptor (MC2R) and activates the signaling cascade leading to steroid biosynthesis in the adrenal cortex. Whereas MC2R regulation has been studied using mammalian models, little is known about the molecular mechanisms involved in ACTH signaling in nonmammalian vertebrates. A full-length cDNA encoding MC2R was sequenced from rainbow trout (Oncorhynchus mykiss) interrenal tissue (analogous to the adrenal cortex in mammals) and showed about 60 and about 44% amino acid sequence similarity to teleosts and humans, respectively. Phylogenetic analysis confirmed that MC2R from all species clustered together and was distant from other MCRs. Quantitative real-time PCR revealed a marked tissue-specific difference in MC2R mRNA abundance, with the highest levels observed in the interrenal tissue, ovary, and testis. Acute ACTH, but not alpha-MSH or [Nle4, d-Phe7]-MSH, stimulation resulted in a time- and dose-related elevation in MC2R mRNA abundance in the interrenal tissue. This corresponded with higher steroidogenic acute regulatory protein and cytochrome P450 side-chain cleavage enzyme gene expression as well as elevated cortisol production. An acute stressor transiently elevated plasma ACTH and cortisol levels at 1 h, and this was followed by a significant increase in MC2R mRNA abundance at 4 h after stressor exposure. Taken together, our results demonstrate that ACTH regulation of MC2R is highly conserved in vertebrates, whereas the tissue-specific distribution of this receptor transcript level leads us to propose a role for ACTH signaling in the stressor-mediated suppression of sex steroid levels in fish.
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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".