Ca2+/
calmodulin-dependent protein kinase II alpha (CaMKIIα) is a potential target for acute neuroprotection due to its key role in physiological and pathological
glutamate signaling. The hub domain organizes the
CaMKII holoenzyme into large oligomers, and additional functional effects on
holoenzyme activation have lately emerged. We recently reported that compounds related to the proposed
neuromodulator γ-hydroxybutyrate (GHB) selectively bind to the CaMKIIα hub domain and increase hub thermal stabilization, which is believed to have functional consequences and to mediate neuroprotection. However, the detailed molecular mechanism is unknown. In this study, we functionally characterize the novel and brain permeable GHB analog (E)-2-(5-hydroxy-2-phenyl-5,7,8,9-tetrahydro-6H-benzo[7]annulen-6-ylidene)
acetic acid (Ph-HTBA). Administration of a single dose of Ph-HTBA at a clinically relevant time point (3-6 h after photothrombotic
stroke) promotes neuroprotection with a superior effect at low doses compared to the smaller GHB analog
3-hydroxycyclopent-1-enecarboxylic acid (
HOCPCA). In contrast to
HOCPCA, Ph-HTBA reduces Ca2+-stimulated CaMKIIα Thr286 autophosphorylation in primary cortical neurons and substrate phosphorylation of recombinant CaMKIIα, potentially contributing to its
neuroprotective effect. Supported by previous in silico docking studies, we suggest that Ph-HTBA makes distinct molecular interactions with the hub cavity, which may contribute to its differential functional profile and superior
neuroprotective effect compared to
HOCPCA. Together, this highlights Ph-HTBA as a promising tool to study hub functionality, but also as a good candidate for clinical development.