The LIM homeodomain protein ISL1 mediates the function of TCF7L2 in pancreatic beta cells
Bibliographic record
Abstract
Pancreatic β-cell Tcf7l2 deletion or its functional knockdown suggested the essential role of this Wnt pathway effector in controlling insulin secretion, glucose homeostasis and β-cell gene expression. As the LIM homeodomain protein ISL1 is a suggested Wnt pathway downstream target, we hypothesize that it mediates metabolic functions of TCF7L2. We aimed to determine the role of ISL1 in mediating the function of TCF7L2 and the incretin hormone GLP-1 in pancreatic β-cells. The effect of dominant negative TCF7L2 (TCF7L2DN) mediated Wnt pathway functional knockdown on Isl1 expression was determined in βTCFDN mouse islets and in the rat insulinoma cell line INS-1 832/13. Luciferase reporter assay and chromatin immunoprecipitation were utilized to determine whether Isl1 is a direct downstream target of Tcf7l2 . TCF7L2DN adenovirus infection and siRNA-mediated Isl1 knockdown on β-cell gene expression were compared. Furthermore, Isl1 knockdown on GLP-1 stimulated β-catenin S675 phosphorylation and insulin secretion was determined. We found that TCF7L2DN repressed ISL1 levels in βTCFDN islets and the INS-1 832/13 cell line. Wnt stimulators enhanced Isl1 promoter activity and binding of TCF7L2 on Isl1 promoter. TCF7L2DN adenovirus infection and Isl1 knockdown generated similar repression on expression of β-cell genes, including the ones that encode GLUT2 and GLP-1 receptor. Either TCF7L2DN adenovirus infection or Isl1 knockdown attenuated GLP-1-stimulated β-catenin S675 phosphorylation in INS-1 832/13 cells or mouse islets and GLP-1 stimulated insulin secretion in INS-1 832/13 or MIN6 cells. Our observations support the existence of TCF7L2–ISL1 transcriptional network, and we suggest that this network also mediates β-cell function of GLP-1.
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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 | 0.001 |
| 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 | 0.001 |
| 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".