HIF-1α Stabilization Hampers the Chondrogenic Differentiation of Aged Bone Marrow Mesenchymal Stem Cells by Adenosine A <sub>2A</sub> /A <sub>2B</sub> Receptors Imbalance
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Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Trauma and excessive motion are deleterious to cartilage by triggering HIF-1α stabilization, leading to changes in extracellular adenosine formation via CD73. How these changes affect adenosine A 2A /A 2B receptors activation balance in chondrogenesis is unclear. We used bone marrow mesenchymal stem cells (BM-MSCs) from aged women to investigate the impact of HIF-1α overactivation on adenosine formation from ATP breakdown and subsequent A 2A /A 2B receptor tone-regulating chondrogenesis. The chondrogenic differentiation of BM-MSCs from 27 postmenopausal ( Pm ) women was induced for 14 days with or without DMOG, a prolyl-4-hydroxylase (PHD) inhibitor that increases HIF-1α intracellular accumulation. Chondrogenesis was ascertained by the nuclear translocation of SOX9, type II/X collagen, and MMP13 production and by transcriptomic RNAseq analysis. Changes in the density of adenosine receptors, ecto-NTPDases, and CD73 were assessed by immunofluorescence confocal microscopy. The kinetics of ATP hydrolysis and adenosine formation was performed by HPLC. DMOG-induced HIF-1α transcriptional activity increased cartilage damage biomarkers (MMP13 and type X collagen), while decreasing cell viability, SOX9 nuclear translocation, and type II collagen production. DMOG upregulated pro-inflammatory genes and down-regulated chondrogenic gene transcripts determined by RNAseq. HIF-1α stabilization decreased CD39/CD73 amounts and activity, thus reducing adenosine formation. Hence, changes in the A 2A /A 2B receptor tone resulted in preferential activation of the SCH 442416-sensitive A 2A receptor, which is deleterious to the cartilage. In conclusion, HIF-1α overactivation hampers the chondrogenic differentiation of aged BM-MSCs by decreasing adenosine formation from ATP hydrolysis via CD39/CD73, leading to preferential activation of the high-affinity A 2A versus the chondroprotective A 2B receptor.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| 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