Impact of N‐linked glycans on the dual short fibulin/ <scp>LTBP</scp> ‐4 axes regulating elastogenesis
Bibliographic record
Abstract
Elastic fibers are key extracellular components, providing elasticity to blood vessels, lungs, skin, and bladder. Elastic fiber formation requires the accessory proteins fibulin-4, fibulin-5, and the long and short isoforms of the latent TGFβ binding protein-4 (LTBP-4L/S). We established two molecular axes, LTBP-4L/fibulin-4 and LTBP-4S/fibulin-5, defined similar and distinct functions, and determined the role of N-linked glycans in this context. Glycoproteomic analysis identified the specific N-linked glycans in these proteins. Biophysical analyses revealed that the N-linked glycans of LTBP-4L, but not fibulin-4, were critical for fibulin-4-mediated conformational extension of LTBP-4L, impacting its function and assembly. Biochemical and recombinant removal of N-linked glycans from fibulin-4 enhanced its interaction with tropoelastin and elastic fiber formation, indicating an inhibitory role for these N-glycans. Fibulin-5 strongly interacted with and robustly induced a conformational extension of LTBP-4S, leading to enhanced binding to fibronectin, increased LTBP-4S deposition, and doubling of elastic fiber formation. Loss of N-linked glycans from fibulin-5, but not LTBP-4S, reduced their interaction by about 10-fold and abolished the ability of fibulin-5 to extend LTBP-4S conformationally. The presence of fibulin-5-extended LTBP-4S did not trigger tropoelastin aggregation in an in vitro assembly assay but boosted elastic fiber-like assembly massively when fibulin-4 and LTBP-4L were additionally present, suggesting synergistic effects. N-linked glycans in fibulin-5 were essential in this process. The study uncovers novel mechanisms that regulate elastic fiber formation, including overlapping and distinct roles of the LTBP-4L/fibulin-4 and the LTBP-4S/fibulin-5 axes and the importance of N-linked glycans of each of these proteins.
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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 | 0.001 | 0.001 |
| 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".