Analysis of Mammalian Septin Expression in Human Malignant Brain Tumors
Bibliographic record
Abstract
Septins are a highly conserved subfamily of GTPases that play an important role in the process of cytokinesis. To increase our understanding of the expression and localization of the different mammalian septins in human brain tumors, we used antibodies against septins 2, 3, 4, 5, 6, 7, 9, and 11 in immunofluorescence and Western blot analyses of astrocytomas and medulloblastomas. We then characterized the expression and subcellular distribution of the SEPT2 protein in aphidicolin-synchronized U373 MG astrocytoma cells by immunofluorescence and fluorescence-activated cell sorter analysis. To determine the role of SEPT2 in astrocytoma cytokinesis, we inducibly expressed a dominant-negative (DN) SEPT2 mutant in U373 MG astrocytoma cells. We show variable levels and expression patterns of the different septins in brain tissue, brain tumor specimens, and human brain tumor cell lines. SEPT2 was abundantly expressed in all brain tumor samples and cell lines studied. SEPT3 was expressed in medulloblastoma specimens and cell lines, but not in astrocytoma specimens or cell lines. SEPT2 expression was cell cycle-related, with maximal levels in G2-M. Immunocytochemical analysis showed endogenous levels of the different septins within the perinuclear and peripheral cytoplasmic regions. In mitosis, SEPT2 was concentrated at the cleavage furrow. By immunocytochemistry and flow cytometry, we show that a DN SEPT2 mutant inhibits the completion of cell division and results in the accumulation of multinucleated cells. These results suggest that septins are variably expressed in human brain tumors. Stable expression of the DN SEPT2 mutant leads to a G2-M cell cycle block in astrocytoma cells.
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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".