Activity-dependent sulfhydration of serine racemase controls synaptic plasticity in the hippocampus via increasing D-serine availability

Aims More and more advances show that hydrogen sulfide （H2S） sulfhydrates functional proteins and regulates their actions. However, much less is known about the endogenous sulfhydration of key proteins under physiological conditions. Methods Biotin-switch assay, electrophysiological recording, RNA interference, full ESI-MS scan et al. Results Herein, we found that the protein sulfhydration was dynamically regulated by neuro- nal activity. H2S sulfhydrated and activated serine racemase （SR） in the hippocampus, resuhantly increased D- serine level. Notably, sulfhydration of SR was markedly promoted by neuronal stimulation and underlay activity-de- pendent changes of D-serine availability. Both genetic knockdown and pharmacological inhibition of cystathionine β-synthase （CBS）, the key H2S-producing enzyme in brain, attenuated hippoeampal long-term potentiation （LTP） , which can be reversed by exogenous supplement of H2S or D-serine. We also observed that the increase in LTP induced by H2S is dependent on D-serine and polysulfides. In aged rats, sulfhydration of SR was significantly decreased. Furthermore, exogenous supplement of H2S restored the level of sulfhydration and reversed the age-re- lated deficits in hippocampal LTP. Conclusion Our data provide direct evidence for the biological significance of endogenous sulfhydration in physiological conditions and demonstrate a pivotal role of activity-dependent sulfhydra- tion in synaptic plasticity.