The Molecular Mechanism of Endoplasmic Reticulum Stress-Induced Apoptosis in PC-12 Neuronal Cells: The Protective Effect of Insulin-Like Growth Factor I
Bibliographic record
Abstract
Endoplasmic reticulum (ER) stress has been implicated in several neurodegenerative diseases. Although CCAAT/enhancer-binding protein homologous protein (CHOP) has been shown to play a critical role in ER stress, the precise apoptosis cascade downstream of CHOP is unknown. In this report, we investigated the mechanism of ER stress-mediated apoptosis as well as the action of IGF-I in PC-12 neuronal cells. Our results demonstrated that tribbles-related protein 3 (TRB3), which is a target gene of CHOP, was responsible for tunicamycin (an ER stress inducer)-induced apoptosis. TRB3 could promote dephosphorylation of Akt in PC-12 cells. IGF-I inhibited ER stress-induced apoptosis by restoring the phosphorylation level of Akt. Both wortmannin (a phosphatidylinositide 3-kinase inhibitor) and SB 212090 (a p38 MAPK inhibitor) suppressed the protective effect of IGF-I on ER stress-induced apoptosis. Interestingly, IGF-I attenuated ER stress-mediated expression of TRB3 but not CHOP. This action of IGF-I was abolished by SB 212090 but not by wortmannin. Immunoprecipitation analysis revealed that IGF-I promoted the phosphorylation of CHOP by activating p38 MAPK, probably leading to a decrease in the transcriptional activity of CHOP. The dephosphorylation of Akt resulted in increased expression of a proapoptotic protein, p53 up-regulated modulator of apoptosis (PUMA), in a forkhead box O3a-dependent manner. Knockdown of PUMA by short hairpin RNA attenuated ER stress-mediated apoptosis. Thus, our current study indicates that both TRB3 and PUMA are critical molecules in ER stress-induced apoptosis. IGF-I effectively protects PC-12 neuronal cells against ER stress-induced apoptosis through the phosphatidylinositide 3-kinase/Akt and p38 MAPK pathways.
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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 | 0.001 | 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".