Investigating the roles of BMPs during chondrocyte maturation
Bibliographic record
Abstract
Endochondral ossification is a process in which embryonic cartilage serves as a template for bone formation. Cartilage cells called chondrocytes are set in a proteoglycan (PG)-rich matrix, where chondrocytes undergo a developmental transition termed “maturation” or hypertrophy, and express chondrocyte maturation markers such as prehypertrophic marker, Indian hedgehog (Ihh), and the hypertrophic markers, Collagen type X (Col10a1) and alkaline phosphatase (Alpl). During chondrocyte maturation, Ihh induces cells in the surrounding perichondrium to differentiate into perichondral bone. Bone morphogenetic proteins (BMPs) are growth factors that belong to the transforming growth factor-beta (TGF-) superfamily of signalling proteins. These proteins interact with cell-surface receptors and transduce intracellular downstream signalling via SMAD transcription factor complexes (SMAD-1,5,9). These complexes are then translocated into the nucleus where several markers of chondrocyte maturation (ihh, col10a1, and alkaline phosphatase) are transcribed. Previous studies have demonstrated that ihh, col10a1 and alpl are targets of the BMP signalling pathway. However, the regulation of chondrocyte maturation by Bmps still needs to be investigated to substantiate which BMPs are involved in chondrocyte maturation. With over 20 different BMPs under study, Bmp4 and Bmp7 are implicated in chondrocyte maturation. Current literature using the in vitro cell culture model suggests that Bmp4 promotes chondrocyte maturation and Bmp7 suppresses chondrocyte maturation. Here, we aim to test the hypothesis that Bmp4 and Bmp7 have positive and negative roles, respectively, during chondrocyte maturation. To test this hypothesis, ATDC5 cells and transgenic zebrafish were used for in vitro and in vivo experiments, respectively. Contradictory to the proposed hypothesis, the results from our in vitro RT-qPCR assay suggest that the chondrocyte maturation is negatively regulated under Bmp4 and positively regulated under Bmp7. The alcian blue histological staining showed that neither Bmp4 nor Bmp7 individually impacts the production of sulfated GAGs. This result may indicate that these Bmps might be under the influence of some other signalling factors. Data from ALP activity assay and immunofluorescence for ColX are contradictory to each other. Bmp4 appears to promote ALP activity on day 7 while Bmp7 significantly upregulates ColX levels on day 7. On the other hand, our in vivo RT-qPCR assays performed on the transgenic bmp zebrafish demonstrate that both Bmp4 and Bmp7a upregulate the transcript levels of col10a1 and ihha. This may indicate that both the Bmps might influence maturation in vivo. Alcian blue and Alizarin red histological staining reveal the presence of perichondral bone in transgenic bmp7a and not in transgenic bmp4 zebrafish.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".