Abstract 300: Leptin Promotes the Osteoblast Differentiation and Mineralization of Primary Cultures of Vascular Smooth Muscle Cells by Regulating GSK-3β
Bibliographic record
Abstract
Obesity is an independent risk factor for cardiovascular disease (CVD) although the precise molecular mechanisms that link obesity to CVD are not understood. Recent studies suggest that factors secreted by adipose tissue may play an adverse role in cardiovascular health. We have previously demonstrated that the adipocytokine, leptin, promotes vascular calcification in apolipoprotein E - deficient mice and that this increase in calcification is associated with an increase in the expression of several osteoblast-specific markers within the vessel wall. In an effort to understand the mechanism by which leptin exerts these effects, we cultured primary bovine aortic smooth muscle cells (BASMCs) in the presence of 0 to 2 μg/ml leptin for up to 12 days. Osteogenic differentiation of BASMCs was determined by an increase in the expression of osteoblast-specific markers, and the induction of both alkaline phosphatase activity and mineralization. Consistent with previous studies, we found that treatment of BASMCs with leptin induced osteoblast differentiation in a dose-dependent manner. To investigate the underlying mechanism, we examined changes in the expression levels of key factors implicated in osteoblast differentiation, including members of the Wnt signaling pathway. We found that exposure to leptin induced the Erk 1/2-dependent inactivation of GSK-3β, through Ser9 phosphorylation, and a subsequent increase in the nuclear accumulation of β-catenin. Transfection of BASMCs with an adenovirus that expressed constitutively active GSK-3β (Ad-GSK-3β S9A) resulted in a > 2-fold increase in GSK-3β activity, a decrease in the expression of the osteoblast-specific marker, osteopontin, and a significant decrease in leptin-induced alkaline phosphatase activity. Together, our results provide a possible mechanism by which elevated leptin concentrations, associated with obesity, promote osteoblast differentiation, and vascular calcification in vivo.
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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".