Protein Kinase C-βII Is an Apoptotic Lamin Kinase in Polyomavirus-transformed, Etoposide-treated pyF111 Rat Fibroblasts
Bibliographic record
Abstract
The role of protein kinase C-beta(II) (PKC-beta(II)) in etoposide (VP-16)-induced apoptosis was studied using polyomavirus-transformed pyF111 rat fibroblasts in which PKC-beta(II) specific activity in the nuclear membrane (NM) doubled and the enzyme was cleaved into catalytic fragments. No PKC-beta(II) complexes with lamin B1 and/or active caspases were immunoprecipitable from the NM of proliferating untreated cells, but large complexes of PKC-beta(II) holoprotein and its catalytic fragments with lamin B1, active caspase-3 and -6, and inactive phospho-CDK-1, but not PKC-beta(I) or PKC-delta, could be immunoprecipitated from the NM of VP-16-treated cells, suggesting that PKC-beta(II) is an apoptotic lamin kinase. By 30 min after normal nuclei were mixed with cytoplasms from VP-16-treated, but not untreated, cells, PKC-beta(II) holoprotein had moved from the apoptotic cytoplasm to the normal NM, and lamin B1 was phosphorylated before cleavage by caspase-6. Lamin B1 phosphorylation was partly reduced, but its cleavage was completely prevented, despite the presence of active caspase-6, by adding a selective PKC-betas inhibitor, hispidin, to the apoptotic cytoplasms. Thus, a PKC-beta(II) response to VP-16 seems necessary for lamin B1 cleavage by caspase-6 and nuclear lamina dissolution in apoptosing pyF111 fibroblasts. The possibility of PKC-beta(II) being an apoptotic lamin kinase in these cells was further suggested by lamin B1-bound PKC-delta being inactive or only slightly active and by PKC-alpha not combining with the lamin.
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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) | 0.001 | 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 | 0.001 | 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 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".