2177-P: Role of De Novo Sphingolipid Metabolites in Oleate-Induced Pancreatic ß-Cell Proliferation in Rats
Bibliographic record
Abstract
Fatty acids (FA) are major regulators of pancreatic β-cell function. In a rat model of nutrient excess we previously showed that FA potentiate glucose-induced β-cell proliferation. Sphingolipids, derived from the intracellular metabolism of FA, act as cellular mediators in the regulation of pancreatic β-cell function. However, the contribution of sphingolipid species to FA-induced β-cell proliferation is unknown. Objective: To determine the role of de novo sphingolipid synthesis in FA-induced β-cell proliferation. Methods: Isolated rat islets were exposed to oleate or palmitate (0.5 mM) in the presence of 16.7 mM glucose for 48h. Sphingosine kinase (SphK) 1 and 2 expression was measured by real-time PCR. Serine palmitoyl transferase (SPT), SphK, and the S1P3 receptor were inhibited with Myriocin, SKI II and TY52156, respectively. β-cell proliferation was assessed in cryosections by immunohistochemical detection of insulin and the proliferation marker Ki67 or by flow cytometry by labeling for C-peptide and EdU incorporation. Wistar rats were infused for 72 hours with glucose and a lipid emulsion (CLI) to induce β-cell proliferation. Results: The monounsaturated FA oleate, but not the saturated FA palmitate, increased β-cell proliferation. Blocking de novo sphingolipid synthesis by SPT inhibition decreased oleate-induced β-cell proliferation as did inhibition of SphK and S1P3 receptor activation. Sphk1/2 mRNA levels in islets were not significantly changed following nutrient infusion in rats or FA exposure ex vivo. Conclusion: β-cell proliferation in response to oleate requires de novo sphingolipid synthesis and S1P3 signaling. Analyses are underway to assess the contribution of SphK products sphingosine-1-phosphate and dihydrosphinganine-1-phosphate in S1P3-mediated β-cell proliferation. Disclosure A. Castell: None. A. Vivoli: None. V.S. Moullé: None. J. Ghislain: None. V. Poitout: None. Funding National Institutes of Health; Canadian Institutes of Health Research
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 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".