Calnexin Silencing in Mouse Neonatal Cardiomyocytes Induces Ca<sup>2+</sup> Cycling Defects, ER Stress, and Apoptosis
Bibliographic record
Abstract
Calnexin (CNX) is an endoplasmic reticulum (ER) quality control chaperone that has been implicated in ER stress. ER stress is a prominent pathological feature of various pathologic conditions, including cardiovascular diseases. However, the role of CNX and ER stress has not been studied in the heart. In the present study, we aimed to characterize the role of CNX in cardiomyocyte physiology with respect to ER stress, apoptosis, and cardiomyocyte Ca(2+) cycling. We demonstrated significantly decreased CNX mRNA and protein levels by LentiVector mediated transduction of targeting shRNAs. CNX silenced cardiomyocytes exhibited ER stress as evidenced by increased GRP78 and ATF6 protein levels, increased levels of spliced XBP1 mRNA, ASK-1, ERO1a, and CHOP mRNA levels. CNX silencing also led to significant activation of caspases-3 and -9. This activation of caspases was associated with hallmark morphological features of apoptosis including loss of sarcomeric organization and nuclear integrity. Ca(2+) imaging in live cells showed that CNX silencing resulted in Ca(2+) transients with significantly larger amplitudes but decreased frequency and Ca(2+) uptake rates in the basal state. Interestingly, 5 mM caffeine stimulated Ca(2+) transients were similar between control and CNX silenced cardiomyocytes. Finally, we demonstrated that CNX silencing induced the expression of the L-type voltage dependent calcium channel (CAV1.2) but reduced the expression of the sarcoplasmic reticulum ATPase (SERCA2a). In conclusion, this is the first study to demonstrate CNX has a specific role in cardiomyocyte viability and Ca(2+) cycling through its effects on ER stress, apoptosis and Ca(2+) channel expression.
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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".