Identification of Several Connexins Expressed in Porcine Cumulus Oocyte Complex and Their Transcriptional Regulation During the First Hours of In Vitro Maturation.
Bibliographic record
Abstract
Gap junction intercellular communication (GJC) plays an important role in ovarian cell physiology. Closure of GJC in the cumulus oocyte complex has been proposed to be involved in oocyte maturation, particularly in the resumption of meiosis, by controlling the flow of meiosis inhibitors such as cAMP and cGMP. GJC results from mutual docking of plasma membrane hemi-channels composed of six proteins subunits called connexins (Cx). GJC consist of one or more types of connexin, which interact with each other to form homomeric channels (composed of the same sort of Cx) or heteromeric channels (composed of different sort of Cx). The ability of the cell to vary gap junction structure in this manner increases the possibilities for regulating specific permeability. We have previously shown that cumulus cells are crucial during the first 4 hours of porcine in vitro maturation, driving meiotic resumption, and that GJC between cumulus cells is highly regulated by gonadotropins during this time period. Based on these results, we hypothesized that several connexins are expressed in the porcine cumulus oocyte complex to regulate GJC and that expression of these connexins is directed by gonadotropins during the first few hours of in vitro maturation. We first use a classic PCR approach to identified connexins expressed into the cumulus oocyte complex and localized their main expression in the oocyte or cumulus cells. We show that Cx43, Cx45 and Cx60 transcripts are present in the porcine cumulus oocyte complex while Cx26 and Cx32 are weakly expressed and we were not able to find any transcript of Cx37 or Cx30.3. We found that Cx60 is expressed in the oocyte, Cx43 in cumulus cells and Cx45 is expressed both in cumulus cells and the oocyte. Then, we used real time PCR to address whether or not expression of these connexins were regulated by gonadotropins during the first hours of maturation. We show that pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) acted in concert to increase by almost four times Cx43 transcripts in cumulus cells after 4.5h of maturation. Neither PMSG nor hCG alone in the culture medium were able to reproduce an increase in Cx43 expression. In contrast, expression of Cx45 and Cx60 is halved during the first hours of maturation. These results support that Cx43 is expressed in cumulus cells, Cx60 in the oocyte and Cx45 in both. Gonadotropins regulate the expression of these connexins during the first few hours of in vitro maturation. PMSG and hCG act together on cumulus cells to increase Cx43 expression after 4.5 hours of maturation whereas expression of Cx45 and Cx60 decreased. These findings improve our efforts to decipher the regulation of GJC during in vitro maturation and thus oocyte maturation. This study provides evidence that the composition of the IVM medium in terms of gonadotropins clearly affects connexins expression, which may in turn affect meiotic resumption and consequently the development of a competent oocyte.
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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 | 0.001 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".