AMPK Deletion in the Intestinal Epithelium Reveals Region‐Specific Roles in Health and Disease
Bibliographic record
Abstract
AMP‐Activated Protein Kinase (AMPK) is a conserved energy sensor that has been suggested to modulate intestinal barrier function. Intestinal barrier function contributes to partitioning of the gut lumen and lamina propria and is primarily mediated by intestinal epithelial cell (IEC) control of permeability, ion transport, and regulation of cell turnover. Dysfunction of the intestinal barrier is a feature of pathologies such as Inflammatory Bowel Disease (IBD) and diarrhea. The aim of this study was to identify the impact of AMPK activity on intestinal barrier function by utilizing a tissue‐specific knockout mouse model lacking both AMPK‐α catalytic isoforms. Methods Intestinal epithelial‐specific AMPK knockout mice (AMPKα Δ IEC KO ) were created by crossing Prkaa1 and Prkaa2 floxed mice (AMPKα fl/fl ) with Villin‐Cre mice. Large intestine (cecum, proximal, and distal colon) was stripped of the seromuscular layer and mounted in Ussing chambers containing Kreb’s Ringer’s buffer. Transepithelial electrical resistance (TER), 4 kDa FITC‐dextran (FD4) permeability and ion transport responses to Forskolin (20 μM, bilateral) and Carbachol (300 μM, serosal) were measured. Protein expression was analyzed in isolated IECs or whole tissue by immunoblotting or by immunostaining of whole intestinal tissue. Colitis was induced by 5% Dextran Sodium Sulfate (DSS) in drinking water (ad libitum for 5 days) followed by 3 days of water. Results AMPKα Δ IEC KO mice had decreased TER only in the proximal colon vs. AMPKα fl/fl mice (p = 0.057, n = 6–7), with no change in FD4 permeability. Decreased TER in the proximal colon was associated with reduced Claudin‐4 expression. Claudin‐4 in the distal colon was significantly decreased in AMPKα Δ IEC KO mice (48% decrease, p = 0.0136, n = 5). Ion transport responses to Carbachol were increased in the cecum of AMPKα Δ IEC KO mice vs . AMPKα fl/fl mice (p = 0.012, n = 3), while Forskolin responses were unchanged. Expression of the AMPK‐regulated ion transport protein, Na + ‐K + ‐Cl − Cotransporter 1 (NKCC1) was increased in the cecum and distal colon of AMPKα Δ IEC KO vs . AMPKα fl/fl mice, thus indicating that AMPK repressed NKCC1 expression in these regions (p<0.05 ‐ p<0.001). Inflammatory challenge (DSS colitis) caused increased cell death (TUNEL staining) in cecum and distal colon but TUNEL staining was reduced in the cecum of AMPKα Δ IEC KO mice vs . AMPKα fl/fl mice (6.2‐fold, p = 0.0241, n = 2–3). Consistent with unaltered TUNEL staining in the proximal colon, the apoptosis markers cleaved caspase‐3 and PARP‐1 were also reduced in both mouse genotypes. However, despite increased TUNEL staining, these cleavage events were not increased in the cecum or distal colon of DSS‐treated mice suggesting cell death occurred by a mechanism independent of caspase‐3 and PARP cleavage. Conclusions Epithelial AMPK regulation of intestinal barrier permeability, ion transport, and inflammation‐induced cell death displays regional heterogeneity along the large intestine. Support or Funding Information NIH 2R01DK091281 (DFM)
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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) | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".