Na/K-ATPase and Regulation of Sperm Function
Bibliographic record
Abstract
A standard bull breeding soundness evaluation (BBSE) identifies bulls with semen that is grossly abnormal. Nonetheless, semen samples classified as satisfactory based on these traditional approaches differ in fertility; perhaps there are submicroscopic differences in sperm characteristics affecting fertility. Therefore, a better understanding of molecular regulation of sperm function could promote development of novel, evidence-based approaches to predict male fertility. Recently the α4 isoform of Na/K-ATPase (ATP1A4) has received considerable attention, due to its testis- specific expression in post-meiotic germ cells and mature sperm, in addition to its regulation of sperm motility and capacitation. Using fresh bull sperm, we determined that ATP1A4 resided in specialized microdomains (raft and non-raft) of the sperm plasma membrane and activated specific signaling (caveolin-1, EGFR, Src, ERK1/2) molecules during sperm capacitation. Furthermore, ATP1A4 was the predominant isoform responsible for total Na/K-ATPase activity in capacitated sperm. Despite the widely accepted dogma of transcriptional/translational quiescence, bovine sperm translated ATP1A4 mRNA on mitochondrial or mitochondrial-type ribosomes, increasing their content and activity during capacitation. Proteomic analysis of raft and non-raft fractions revealed a significant interaction between ATP1A4 and plakoglobin, a member of the β-catenin family of proteins involved in cell adhesion, in the equatorial segment of capacitated sperm, suggesting a potential role in sperm-oolemma fusion. In frozen-thawed sperm, ATP1A4 content and activity was greater in high- versus low-fertility bulls. Additionally, ATP1A4-induced increases in ROS, calcium, actin polymerization and tyrosine phosphorylation were also involved in regulating post-thaw sperm function in these bulls. Overall, results demonstrated that ATP1A4 had unique roles in controlling several aspects of sperm physiology, acting through well-established enzyme activity and signaling functions. Consequently, isoforms of Na/K-ATPase are potential biomarkers for male fertility.
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How this classification was reachedexpand
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 | 0.000 |
| 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 | 0.000 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".