Direct Regulation of the Proglucagon Gene by Insulin, Leptin, and cAMP in Embryonic versus Adult Hypothalamic Neurons
Bibliographic record
Abstract
The proglucagon gene is expressed not only in the pancreas and intestine but also in the hypothalamus. Proglucagon-derived peptides have emerged as potential regulators of energy homeostasis. Whether leptin, insulin, or cAMP activation controls proglucagon gene expression in the hypothalamus is not known. A key reason for this has been the inaccessibility of hypothalamic proglucagon-expressing neurons and the lack of suitable neuronal cell lines. Herein we describe the mechanisms involved in the direct regulation of the proglucagon gene by insulin, leptin, and cAMP in hypothalamic cell models. Insulin, through an Akt-dependent manner, significantly induced proglucagon mRNA expression by 70% in adult-derived mHypoA-2/10 neurons and significantly suppressed it by 45% in embryonic-derived mHypoE-39 neurons. Leptin, via the Janus kinase-2/ signal transducer and activator of transcription-3 pathway, caused an initial increase by 66 and 43% at 1 h followed by a decrease by 45 and 34% at 12 h in mHypoA-2/10 and mHypoE-39 cells, respectively. Furthermore, cAMP activation by forskolin up-regulated proglucagon expression by 87% in mHypoE-39 neurons and increased proglucagon mRNA, through Epac activation, in the mHypoE-20/2 neurons. Specific regions of the proglucagon promoter were regulated by cAMP signaling, as determined by transient transfections, whereas mRNA stability assays demonstrate that insulin and leptin increase proglucagon mRNA stability in the adult cells. These findings suggest that insulin, leptin, and cAMP act directly, but differentially, on specific hypothalamic neurons to regulate proglucagon gene expression. Because proglucagon-derived peptides are potential regulators of energy homeostasis, an understanding of hypothalamic proglucagon neurons is important to further expand our knowledge of alternative feeding circuits.
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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".