AMP-Activated Protein Kinase Activation May Not Be Involved in AICAR- and Metformin-Mediated Meiotic Arrest in Bovine Oocytes.
Bibliographic record
Abstract
It was recently suggested that 5'-AMP may be involved in meiotic induction in mouse oocytes through activation of AMP-activated protein kinase (AMPK). However, we have shown that the AMPK activators 5'-aminoimnidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) and metformin (MET) inhibited the resumption of meiotic maturation in bovine cumulus-enclosed and denuded oocytes in culture. The objectives of this study were 1) to examine the effects of AMPK inhibitors on bovine oocyte nuclear maturation in vitro; 2) using an enzyme assay, determine whether AICAR and MET activated oocyte AMPK; and 3) determine whether these agents resulted in phosphorylation of Thr172 on the alpha subunit of AMPK. The AMPK inhibitor Compound C (CC) did not reverse the inhibitory effect of AICAR and MET on bovine oocyte meiosis; additionnally, CC inhibited meiosis in cumulus-enclosed and denuded oocytes cultured for 7 h. Only the highest concentration used had a significant effect after 21 h of culture. Both the AMPK activator Adenine 9-β-D-arabinofuranoside 5'-monophosphate (AraAMP) and the AMPK inhibitor Adenine 9-β-D-arabinofuranoside (AraA) inhibited meiosis in cumulus-enclosed oocytes cultured for 7 h. These molecules were without effects when the culture period was extended to 21 h. Okadaic acid reversed the inhibitory effect of MET and CC but not of AICAR indicating that AICAR may inhibit meiosis by a different mechanism. AMPK activity was measured in oocyte extracts by labeling of the AMARA peptide with [γ-32P]ATP. Extracts from COC cultured with AICAR had higher AMPK activity compared to extracts from COC cultured in control conditions; however, the DO response to AICAR was highly variable and non-significant. Phosphorylation of the alpha subunit of AMPK on Thr172 is required for activation. We performed Western analysis of proteins extracted from denuded oocytes and oocytes from cumulus-oocyte complexes after culture in the presence of AICAR and MET at inhibitory concentrations. Preliminary analysis suggest that culture with these agents did not increase Thr172 phosphorylation level in denuded oocytes and oocytes from complexes compared to culture in control medium. Different antibodies will be tested to confirm these results. Taken together, these results indicate that the inhibitory effect of AICAR and MET on bovine oocyte nuclear maturation may not be due to activation of AMPK. Moreover, AICAR and MET may inhibit meiosis by different mechanisms. (poster)
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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 | 0.000 |
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 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".