DOT1L is widely framed as a transcription-elongation factor, but the one direct test found in erythroleukaemic cells reported a role in initiation - in a non-KMT2A-rearranged line, so it is a counter-lead for the elongation model, not a refutation
also called DOT1L elongation versus initiation · DOT1L complex TBP occupancy
Many descriptions of how DOT1L drives this leukaemia say it helps the cell's copying machinery keep running along a gene. One 2021 study that tested this directly in a different leukaemia cell line found DOT1L mattered more at the start of a gene than along it. That line does not carry the KMT2A fusion, so the result is a reason to check, not a reason to change the picture.
The same thing, for a scientist
Bearing on the DOT1L mechanism, not the menin interface. The corpus links DOT1L to elongation in 88 node files by a proximity search (DOT1L within 80 characters of 'elongation'); this is a co-mention count, not a count of entries asserting it. None cites PMID 34187895. In human erythroleukaemic cells (K562 background, not KMT2A-rearranged), the authors report that DOT1L depletion reduced global DOT1L occupancy without changing the Pol II traveling ratio or elongation rate (4sU-DRB-seq), and that DOT1L and ENL depletion each reduced TBP occupancy and, on a fraction of direct targets, Pol II occupancy, which they read as an initiation role. Proteomic and biochemical work in the abstract suggests recruitment or stabilisation of TFIID, possibly H2Bub1-enhanced, and DOT1L limiting SAGA recruitment to raise H2Bub1.
What was found and in what system
Read from the PubMed abstract (fetched 2026-10-07). The abstract states the prevailing view the authors set out to test: that DOT1L regulates elongation, inferred from colocalisation with Pol II, subunits shared between the DOT1L complex and the super elongation complex (AF9, ENL), and the spread of H3K79 methylation over promoters and gene bodies 1. Their result in human erythroleukaemic cells is that depleting DOT1L did not change the traveling ratio or the elongation rate, while DOT1L or ENL depletion lowered TBP occupancy at thousands of genes 1. Pol II and TBP fell together at a significant fraction of DOT1L-bound genes 1. The abstract ends by saying the work has implications for MLL-rearranged leukaemia; it does not report experiments in KMT2A-rearranged cells.
Why this is a lead and not a correction
The system is not the disease: erythroleukaemic cells are not KMT2A-rearranged, and the fusion changes who DOT1L is recruited by (through AF9/ENL-type contacts on the fusion partner side). A mechanism seen without the fusion may not hold with it. Equally, 88 co-mentions cannot be read as 88 settled claims: the corpus needs a pass to separate entries that assert elongation from entries that only mention it. That pass is the task this entry creates.
| corpus comention count | 88 |
|---|---|
| corpus comention method | grep -rliE 'DOT1L.{0,80}elongation|elongation.{0,80}DOT1L' over data/graph/nodes on 2026-10-07; proximity match, not assertion |
| geo | GSE161367 |
- If DOT1L acts partly at initiation, pharmacodynamic readouts for DOT1L inhibitors that rest on elongation markers (traveling ratio, Pol II pausing) may miss or misread target engagement.
- A combination rationale that treats DOT1L and super-elongation-complex inhibition as hitting the same elongation step would need rechecking if the DOT1L step is partly initiation.
- How many of the 88 entries assert an elongation role as established, and how many merely mention it? Triage by hand.
- Does the same Pol II / TBP pattern hold in a KMT2A-rearranged line (SEM, RS4;11, MV4-11) after DOT1L or pinometostat treatment?
- GSE161367 is a 74-sample ChIP and 4sU-DRB-seq deposit; is a re-analysis in the rearranged-line context available from another group?
- E1moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
In human erythroleukaemic cells, DOT1L depletion reduced DOT1L occupancy without changing the Pol II traveling ratio or elongation rate, and DOT1L or ENL depletion reduced TBP occupancy, which the authors interpret as a role in transcription initiation.
DOT1L complex regulates transcriptional initiation in human erythroleukemic cells · Wu A, Zhi J, Tian T, et al. · Proc Natl Acad Sci U S A 2021What this evidence cannot show
Abstract read only; full text and methods not read. Cell system is erythroleukaemic, not KMT2A-rearranged. Depletion experiments, not inhibitor experiments, so catalytic and scaffolding roles are not separated in what I have read. The authors' own abstract describes the elongation view as one that had been 'believed', so the field's position is that it was inferred, not that it was tested and confirmed.
Evidence that argues against this (1)
- The result comes from one non-rearranged cell system. A KMT2A-fusion cell may recruit DOT1L differently, so an elongation role there is not excluded by this paper. The related GEO series GSE161367 (74 samples) holds the underlying data and was not re-analysed here.
elongation versus initiation role of the DOT1L complex
ENL depletion reduced TBP occupancy alongside DOT1L