Luteolin inhibition of V‐ATPase <i>a3</i>–<i>d2</i> interaction decreases osteoclast resorptive activity
Bibliographic record
Abstract
V-ATPase-mediated acid secretion is required for osteoclast bone resorption. Osteoclasts are enriched in V-ATPase a3 and d2 subunit isoforms, and disruption of either of their genes impairs bone resorption. Using purified fusion proteins of a3 N-terminal domain (NTa3) and full-length d subunits we determined in a solid-phase binding assay that half-maximal binding of d1 or d2 to immobilized NTa3 occurs at 3.1 ± 0.4 or 3.6 ± 0.6 nM, respectively, suggesting equally high-affinity interactions. A high-throughput modification of this assay was then used to screen chemical libraries for a3-d2 interaction inhibitors, and luteolin, a naturally occurring flavonoid, was identified, with half-maximal inhibition at 2.4 ± 0.9 µM. Luteolin did not significantly affect NIH/3T3 or RAW 264.7 cell viability, nor did it affect cytokine-induced osteoclastogenesis of RAW 264.7 cells or bone marrow mononuclear cells at concentrations ≤ 40 µM. Luteolin inhibited osteoclast bone resorption with an EC(50) of approximately 2.5 µM, without affecting osteoclast actin ring formation. Luteolin-treated osteoclasts produced deeper resorption pits, but with decreased surface area, resulting in overall decreased pit volume. Luteolin did not affect transcription, or protein levels, of V-ATPase subunits a3, d2, and E, or V(1) V(0) assembly. Previous work has shown that luteolin can be effective in reducing bone resorption, and our studies suggest that this effect of luteolin may be through disruption of osteoclast V-ATPase a3-d2 interaction. We conclude that the V-ATPase a3-d2 interaction is a viable target for novel anti-resorptive therapeutics that potentially preserve osteoclast-osteoblast signaling important for bone remodeling.
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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".