Reduced histone biotinylation in multiple carboxylase deficiency patients: a nuclear role for holocarboxylase synthetase
Bibliographic record
Abstract
The attachment of biotin to apocarboxylases is catalyzed by holocarboxylase synthetase (HCS). An inherited deficiency of HCS results in the disorder 'multiple carboxylase deficiency', which is characterized by reduced activity of all biotin-dependent carboxylases. Here we show that the majority of HCS localizes to the nucleus rather than the cytoplasm based on immunofluorescence studies with antibodies to peptides and full length HCS and on the expression of recombinant HCS. Subnuclear fractionations indicate that HCS is associated with chromatin and the nuclear lamina, the latter in a discontinuous distribution in high salt-extracted nuclear membranes. During mitosis, HCS resolves into ring-like particles which co-localize with lamin B. Nuclear HCS retains its biotinylating activity and was shown to biotinylate purified histones in vitro. Significantly, fibroblasts from patients with HCS deficiency are severely deficient in histone biotinylation in addition to the deficiency of carboxylase activities. We propose that the role of HCS in histone modification may be linked to the participation of biotin in the regulation of gene expression or cell division and that affected patients may have additional disease beyond that due to the effect on carboxylases.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".