The Evidence Layer for Scientific AI

 Quick Analysis Plan Copied

 Long Analysis Plan

Mechanistic inference

Negative SPR rules out direct binding to folded recombinant ID1, but does not exclude covalent, allosteric, or cellular-context-dependent interactions. Suppression of all four ID proteins within 24 hours is most consistent with a shared post-translational node. The strongest literature precedent is USP1, the deubiquitinase that stabilizes ID1; USP1 inhibition (e.g., pimozide, carbodoxime analogs) triggers proteasomal ID1 degradation without any direct ligand–ID1 engagement (USP1 inhibitors promote ID1 degradation). A transcriptional route remains plausible: ID1 is rapidly induced by upstream signals such as TGF-β1 in tubular epithelial cells (TGF-β1 rapidly induces Id1 transcription), and STING–ID1 axis data show ID1 is downstream of stress pathways (STING–ID1 upstream axis). However, a single upstream regulator that simultaneously suppresses ID1, ID2, ID3, and ID4 within 24h is less parsimonious than a shared degradation machinery.

Discriminating experiments

1. Paired mRNA/protein time course (0, 2, 6, 12, 24h X6632): RT-qPCR for ID1–4 + Western blot. Early protein loss with intact mRNA → post-transcriptional. Coordinated mRNA + protein loss → transcriptional.

2. MG132/lactacystin rescue: proteasome inhibitor added 4h before X6632. Full rescue of ID protein levels confirms degradation mechanism.

3. Cycloheximide chase: X6632 should shorten ID1–4 protein half-life in the degradation model, with no effect in the transcriptional model.

4. USP1 activity assay + ubiquitination pull-down: assesses whether X6632 inhibits USP1 or promotes ID ubiquitination, directly testing the mechanistic precedent (USP1 deubiquitinase target for ID1).

5. ID promoter–luciferase and BMP/Smad reporter: unaffected promoter activity despite protein loss further supports post-transcriptional action.

Confidence: moderate — inference based on the known USP1–ID1 degradation axis, not on direct X6632 data. Falsification of the degradation hypothesis: ID1–4 protein remains suppressed in the presence of MG132 and mRNA falls concurrently.