Intestinal Epithelial AMPK Does Not Protect Against High Dose DSS‐Induced Colitis in Mice
Bibliographic record
Abstract
AMP‐Activated Protein Kinase (AMPK) is a master regulator of cellular energy status whose activity requires α1 and α2 isoforms of the catalytic subunit. Recent evidence suggested AMPK protects against DSS‐induced colitis using villin‐Cre AMPKα1 knockout mice and nonspecific pharmacological activators. However, previous studies have not tested if both AMPKα isoforms are required for protection as α1/α2 double‐knockout is embryonic lethal in mice. Moreover, we previously showed AMPKα1 protein is increased in AMPKα2−/− mice, potentially confounding conclusions. Furthermore, the role of intestinal epithelial AMPK in inflammatory responses remains poorly understood. The goals of this study were to determine if AMPK is necessary for intestinal homeostasis and to confirm if intestinal epithelial AMPK is required for protection against colitis in a mouse model. Methods Intestinal epithelial‐specific deletion of both AMPK catalytic isoforms (AMPKα ΔIEC KO ) was generated by crossing villin‐Cre recombinase mice with Prkaa1 and Prkaa2 floxed mice (AMPKα fl/fl ). Barrier integrity and function were assessed histologically, by 40 kDa FITC‐dextran (FD4) intestinal permeability assay and by agonist stimulation of chloride secretion ex vivo in Ussing chambers. Colitis was induced with 5% dextran sulfate sodium (DSS) in drinking water for 5 days, followed by 3 days of water. Body weight, stool consistency and hemoccult were recorded daily to determine disease activity index scores. Intestinal permeability during colitis was determined by FD4 permeability. Mice were euthanized according to institutional IACUC protocols. Tissues were fixed in 4% paraformaldehyde for imaging or flash frozen for protein and RNA analysis. Results Unchallenged AMPKα ΔIEC KO mice showed no histologic changes in intestinal integrity, nor any significant change in intestinal permeability or agonist‐stimulated chloride secretion. Mice administered 5% DSS developed severe colitis indicated by dramatic weight loss and increased disease activity index score compared to untreated controls. Colitis induced similar levels of colonic shortening and increased intestinal permeability in both floxed and AMPKα ΔIEC KO mice, however AMPK‐regulated pro‐inflammatory gene expression was unchanged compared to untreated controls. Despite the lack of an overt phenotypic difference in AMPKα ΔIEC KO mice compared to AMPKα fl/fl mice, we did observe significant differences in protein expression. The tight junction protein claudin 2 was significantly decreased in proximal colon of AMPKα ΔIEC KO mice compared to AMPKα fl/fl mice without DSS challenge. Untreated and DSS‐treated AMPKα ΔIEC KO mice had decreased levels of the apoptosis markers cleaved caspase 3 in ileum, and PARP in proximal colon respectively, while cleaved caspase 3 was increased in distal colon compared to matched AMPKα fl/fl mice. Conclusion Loss of AMPK alone altered levels of claudin 2 and apoptotic markers in intestinal epithelial cells but did not alter DSS‐induced colitis severity. Support or Funding Information NIH 2R01DK091281 (DFM) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".