Epigenetics
Can one enzyme put histamine on histones and take it off?
Open access · cc by · source: Europe PMC
Transglutaminase 2 not only installs serotonin/dopamine on histone H3Q5 but also erases and swaps those marks; histaminylation (H3Q5his) rises and falls over the day, blocks WDR5, and helps set neural circadian gene expression and behavior.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Two monoamine marks at the same residue have opposite effects on the same downstream complex.
Monoaminylation marks are dynamic and regionally specific. Transglutaminase 2 acts as eraser and exchanger as well as writer, and H3Q5 histaminylation is diurnally rhythmic in brain — enriched in the histaminergic tuberomammillary nucleus, the only HDC-positive region — where, unlike H3Q5 serotonylation, it inhibits WDR5 binding and so H3K4 methyltransferase activity.
Evidence for the claim as stated.
These marks are studied in systems that answer different questions. The cancer work links lactylation to outcome and to treatment response in patient-derived models, while the monoaminylation work establishes enzymology and rhythmicity in brain without an outcome — so the strength of evidence for the mark mattering differs by field rather than by mark.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
These marks are studied in systems that answer different questions. The cancer work links lactylation to outcome and to treatment response in patient-derived models, while the monoaminylation work establishes enzymology and rhythmicity in brain without an outcome — so the strength of evidence for the mark mattering differs by field rather than by mark.
Study at a glance
- Design
- Animal / in-vitro — Biochemical, genomic, and mouse work showing TG2 writes/erases H3Q5 monoaminylations, including rhythmic H3Q5his in TMN
- N
- N=25 · Multiple assays; example in vivo n = 12 zolpidem vs 13 vehicle mice plus TMN-focused molecular time courses
- Population
- Biochemical systems, mouse brain (especially histaminergic TMN), and circadian/behavioral assays
- Outcome
- H3Q5ser/dop/his dynamics, WDR5/H3K4 methylation antagonism, circadian gene expression and locomotor rhythmicity
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Can one enzyme put histamine on histones and take it off?
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Zolpidem locomotor assay used 12 vs 13 mice.
Locomotor activity in mice treated with zolpidem ( n = 12 mice) versus vehicle ( n = 13 mice) during their active phase.
H3Q5his, unlike H3Q5ser, inhibits WDR5 and H3K4 methylation.
We found that H3Q5his, in contrast to H3Q5ser, inhibits the binding of WDR5, a core member of histone H3 Lys4 (H3K4) methyltransferase complexes, thereby antagonizing methyltransferase activities on H3K4.
Key findings
TG2 acts as eraser/exchanger as well as writer. H3Q5his is diurnally rhythmic in brain (enriched in histaminergic TMN, the only HDC+ region) and, unlike H3Q5ser, inhibits WDR5 binding and thereby H3K4 methyltransferase activity, linking monoamine microenvironments to neural rhythmicity.
Methodology
Combined enzymology, chromatin binding, TMN-focused genomics, and mouse behavior to test whether TG2 erases/exchanges H3Q5 monoaminylations and whether H3Q5his is rhythmic and functionally distinct from H3Q5ser.
Limitations
Mouse and in vitro chromatin biochemistry cannot yet show that targeting H3Q5his would treat human circadian or psychiatric disorders.
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