Regulation of Muscle Stem Cell Dynamics and Quiescence by Netrin-1 Cytoskeletal Signaling
Bibliographic record
Abstract
Abstract The hallmark property of muscle stem cells (MuSCs) at homeostasis is quiescence. However, MuSCs have cellular protrusions that are heterogeneous, complex, and tipped with filopodia, all signs of motile structures. Such protrusions may serve as sensors of the MuSC niche. Through development of a novel ex vivo live imaging assay for MuSC protrusion dynamics, we report here the identification of a regulatory pathway in this process. The axon guidance cue Netrin-1 promotes MuSC protrusion outgrowth ex vivo in a manner dependent on its receptors Dcc and Neogenin, the small GTPase Rac1, and the actin-branching factor Arp2/3; this pathway is also required for Netrin-dependent axonal growth cone motility. Adult MuSC-specific genetic removal of Netrin-1 receptors, Rac1, and Arp2/3 each result in failure to maintain homeostatic protrusion lengths, spontaneous quiescence exit, and MuSC attrition in uninjured mice. These findings reveal an unanticipated level of morphological dynamism by a quiescent stem cell at homeostasis and link this phenomenon to preservation of the quiescent state.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".