Na<sup>+</sup>/K<sup>+</sup>ATPase regulates sperm capacitation through a mechanism involving kinases and redistribution of its testis‐specific isoform
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Bibliographic record
Abstract
Incubation of bovine sperm with ouabain, an endogenous cardiac glycoside that inhibits both the ubiquitous (ATP1A1) and testis-specific alpha4 (ATP1A4) isoforms of Na(+)/K(+)ATPase, induces tyrosine phosphorylation and capacitation. The objectives of this study were to investigate: (1) fertilizing ability of bovine sperm capacitated by incubating with ouabain; (2) involvement of ATP1A4 in this process; and (3) signaling mechanisms involved in the regulation of sperm capacitation induced by inhibition of Na(+)/K(+)ATPase activity. Fresh sperm capacitated by incubating with ouabain (inhibits both ATP1A1 and ATP1A4) or with anti-ATP1A4 immunoserum fertilized bovine oocytes in vitro. Capacitation was associated with relocalization of ATP1A4 from the entire sperm head to the post-acrosomal region. To investigate signaling mechanisms involved in oubain-induced regulation of sperm capacitation, sperm preparations were pre-incubated with inhibitors of specific signaling molecules, followed by incubation with ouabain. The phosphotyrosine content of sperm preparations was determined by immunoblotting, and capacitation status of these sperm preparations were evaluated through an acrosome reaction assay. We inferred that Na(+)/K(+)ATPase was involved in the regulation of tyrosine phosphorylation in sperm proteins through receptor tyrosine kinase, nonreceptor type protein kinase, and protein kinases A and C. In conclusion, inhibition of Na(+)/K(+)ATPase induced tyrosine phosphorylation and capacitation through multiple signal transduction pathways, imparting fertilizing ability in bovine sperm. To our knowledge, this is the first report documenting both the involvement of ATP1A4 in the regulation of bovine sperm capacitation and that fresh bovine sperm capacitated by the inhibition of Na(+)/K(+)ATPase can fertilize oocytes in vitro.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it