Can one enzyme put histamine on histones and take it off?
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.
Source
Bidirectional histone monoaminylation dynamics regulate neural rhythmicity
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.
What they did
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.
What they found
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.
The limits
What it doesn't show
Mouse and in vitro chromatin biochemistry cannot yet show that targeting H3Q5his would treat human circadian or psychiatric disorders.
Key terms
- H3Q5ser / H3Q5dop / H3Q5his
- Serotonin, dopamine, or histamine covalently attached to histone H3 glutamine 5.
- TG2
- Transglutaminase 2: writer, eraser, and exchanger of H3 monoaminylations.
- WDR5
- Core subunit of H3K4 methyltransferase complexes; binding blocked by H3Q5his not H3Q5ser.
- TMN
- Tuberomammillary nucleus; sole hypothalamic source of HDC+ histaminergic neurons.
- HDC
- Histidine decarboxylase, making histamine from histidine.
- Neural rhythmicity
- Circadian gene expression and behavior influenced by H3Q5his dynamics.
Flashcards
Research intelligence for this paper
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Quiz yourself
TG2 is shown here to be:
Common questions
What new job does TG2 have here?
Eraser and exchanger of H3 monoaminylations, not only writer.
How does H3Q5his differ from H3Q5ser?
It inhibits WDR5 and H3K4 methylation.
Where is histamine made in brain?
TMN neurons expressing HDC.
Is H3Q5his static?
No—it is diurnally rhythmic.
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