Myostatin attenuates hyperplasia and is important for muscle remodeling during compensatory growth
Bibliographic record
Abstract
Myostatin (Mstn) is a TGFβ family growth factor that negatively regulates skeletal muscle growth such that mice lacking this protein display a doubling in muscle mass. To investigate the role for Mstn in muscle fiber remodeling, we compared the effects of functional muscle overload (OV) of the plantaris in Mstn Knockout (Mstn−/−) and C57BL/6 mice. The muscle midbelly area of non‐OV Mstn−/− mice was double that of C57BL/6 counterparts due to a higher number of muscle fibers and fibers displaying greater cross sectional size. OV induced a rapid increase (70%) in plantaris midbelly area of mstn−/− mice due to nascent muscle fibers and without concomitant increases in individual fiber sizes until 6 weeks of OV. C57BL/6 mice displayed a gradual increase (130%) in plantaris midbelly area over 6 weeks in response to OV largely due to muscle fiber hypertrophy. Molecular markers for hyperplasia confirmed this differential response in OV mstn−/− mice. The plantaris of Mstn−/− mice also did not undergo the typical OV‐related fiber type remodeling seen in C57BL/6 mice. These results show that hyperplasia is the major mechanism of muscle growth in OV mstn−/− mice whereas hypertrophy is the prime response in OV C57BL/6 mice. This differential growth pattern may be of importance when considering Myostatin‐related therapies in aging and diseases such as muscular dystrophy. Funded by CIHR, NSERC and CRC.
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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) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".