The Unfolded Protein Response in Skeletal Muscle Adaptations to Exercise
Bibliographic record
Abstract
The unfolded protein responses of both the mitochondria (UPR mt ) and the endoplasmic reticulum (UPR ER ) are important in maintaining cellular homeostasis during stimulus‐induced increases in protein synthesis. Exercise is a well‐established trigger for the synthesis of mitochondrial proteins via organelle biogenesis, regulated by the transcriptional coactivator PGC‐1a. However, little work has focused on the role that the UPR mt and the UPR ER play in exercise‐induced adaptations. To investigate this, we subjected rats to 3 hrs of contractile activity (CCA) for 1, 2, 3, 5 or 7 days, followed by 3 hrs recovery, and examined the gene expression responses involved in early‐onset adaptations to exercise. PGC‐1a mRNA expression increased 12‐fold as early as 1 day of CCA, while the ER chaperone BIP increased in mRNA by 2‐4‐fold between 1‐7 days. Likewise, CHOP expression was elevated 2‐3‐fold throughout 1‐7 days of CCA, while XBP1 mRNA displayed a 47% elevation after 2 days of CCA, but decreased by 26% at 7 days. Expression of upstream UPR mt sensors (LonP, ERa and SirT3) remained unchanged over 7 days of CCA, but the mRNAs encoding the mitochondrial chaperones CPN10, mtHSP70 and HSP60 were elevated by 40‐100% between 2‐7 days of CCA. These changes preceded increases in mitochondrial content and marker proteins such as NQO1. Thus, these findings indicate a potential role of the UPR mt and the UPR ER in early exercise‐induced mitochondrial adaptations in skeletal muscle. Supported by NSERC.
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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".