Vitamin K-dependent carboxylation in osteoblasts regulates bone resorption through GAS6 in male mice
Bibliographic record
Abstract
Abstract Studies in humans suggest that vitamin K is involved in the regulation of bone remodeling, but the precise mechanism at play remains unknown. In cells, vitamin K functions as a co-factor for the γ-glutamyl carboxylase (GGCX), an enzyme responsible for the conversion of glutamic acid residues (Glu) into γ-carboxyglutamic acid (Gla) residues in secreted proteins. We aim here at determining the role of γ-carboxylation in bone remodeling and at identifying the Gla protein(s) involved. We show that male mice lacking γ-carboxylation specifically in osteoblasts ( Ggcx flox/flox ; OCN-Cre ) have increased bone mass at 6 months of age due to a reduced number of multinucleated bone resorbing osteoclasts. In co-culture experiments, Ggcx -deficient osteoblasts were less effective than control osteoblasts at supporting osteoclast formation. Among known Gla proteins, we identify GAS6 as an osteoblast-secreted γ-carboxylated factor which signals to differentiating osteoclasts. The GAS6 receptors MerTK and AXL are expressed in pre-osteoclasts and pharmacological inhibitors of AXL and MerTK block osteoclast generation in co-culture. Conversely, recombinant γ-carboxylated GAS6 dose-dependently increases the size of osteoclasts and the number of nuclei per osteoclast in culture. GAS6 marginally affected the induction of osteoclast-specific genes during osteoclast differentiation but significantly increased pre-osteoclast fusion. Finally, increasing bone marrow GAS6 level in transgenic male mice was sufficient to increase the number and size of osteoclasts and to decrease bone mass. This work identifies GAS6 as a novel osteoblast-derived vitamin K-dependent protein regulating osteoclast maturation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".