Histone variant H2BE controls activity-dependent gene expression and homeostatic scaling.

Neuronal responses to stimuli rely on transcriptional programs controlled by histone proteins, including histone variants. Recent findings demonstrate that the variant H2BE promotes transcription and is critical for long-term memory, which relies on intact activity-dependent responses. However, whether H2BE is regulated by synaptic stimuli and controls activity-dependent responses remains to be determined. Here, we demonstrate that, unlike other variants, H2BE is depleted following long-term but not short-term increases in activity, indicating that its loss may promote homeostatic downscaling. Neurons lacking H2BE are unable to mount proper long-term activity-dependent transcriptional responses both in cultured neurons and in animal models. Lastly, we demonstrate that H2BE-knockout neurons fail to undergo the electrophysiological changes associated with homeostatic plasticity. In summary, these data demonstrate that H2BE expression is inversely correlated with activity and is necessary for long-term activity-dependent scaling responses, revealing a mechanism through which histone variants control homeostatic plasticity in neurons.