<i>Mitf</i> over-expression leads to microphthalmia and coloboma in <i>Mitf-cre</i> mice
Bibliographic record
Abstract
ABSTRACT The Microphthalmia associated transcription factor (Mitf) is a critical regulator of the melanocyte lineage and also plays an important role in eye development. Mitf activity in different cell types is controlled in part by ten alternative promoters and their resulting isoforms. A useful tool for melanocyte-based research, the Mitf-cre transgene was designed to express Cre recombinase from the Mitf-M promoter, which is melanocyte specific. However, Mitf-cre mice are also microphthalmic, perhaps because of insertional mutagenesis or disrupted gene expression. Here, we investigated these possibilities. We determined that the eye phenotype arises early, with Mitf-cre embryos at E13.5 exhibiting variable ocular sizes and abnormalities, but all with coloboma. Targeted locus amplification and next generation sequencing indicated that multiple copies of the transgene integrated into an intergenic region on chromosome 2, in between Spred1 and Meis2 . The BAC transgene used to make Mitf-cre was larger than expected, carrying three upstream alternative promoters, Mitf-H, Mitf-D, and Mitf-B, which could express their isoforms intact off the transgene. RT-qPCR using eye tissue demonstrated a 5-fold increase in Mitf transcripts containing exon 1B1b, which is shared by Mitf-H, Mitf-D, and Mitf-B, while Spred1 and Meis2 did not differ in their expression. These findings clarify and support the usage of Mitf-cre in conditional mutagenesis in melanocytes. The specific over-expression of the Mitf-H and Mitf-D isoforms, which are preferentially expressed in the RPE, presents a unique resource for those interested in eye development and coloboma.
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".