Search

Ca2+/calmodulin-dependent protein kinase II alpha subunit (CaMKIIα) is a key neuronal signaling protein and an emerging drug target. The central hub domain regulates the activity of CaMKIIα by organizing the holoenzyme complex into functional oligomers, yet pharmacological modulation of the hub domain has never been demonstrated. Here, using a combination of photoaffinity labeling and chemical proteomics, we show that compounds related to the natural substance γ-hydroxybutyrate (GHB) bind selectively to CaMKIIα. By means of a 2.2-Å x-ray crystal structure of ligand-bound CaMKIIα hub, we reveal the molecular details of the binding site deep within the hub. Furthermore, we show that binding of GHB and related analogs to this site promotes concentration-dependent increases in hub thermal stability believed to alter holoenzyme functionality. Selectively under states of pathological CaMKIIα activation, hub ligands provide a significant and sustained neuroprotection, which is both time and dose dependent. This is demonstrated in neurons exposed to excitotoxicity and in a mouse model of cerebral ischemia with the selective GHB analog, HOCPCA (3-hydroxycyclopent-1-enecarboxylic acid). Together, our results indicate a hitherto unknown mechanism for neuroprotection by a highly specific and unforeseen interaction between the CaMKIIα hub domain and small molecule brain-penetrant GHB analogs. This establishes GHB analogs as powerful tools for investigating CaMKII neuropharmacology in general and as potential therapeutic compounds for cerebral ischemia in particular.

Ischemic stroke remains a leading cause of disability worldwide, with limited treatment options available. This study investigates GABAC receptors as novel pharmacological targets for stroke recovery. The expression of ρ1 and ρ2 mRNA in mice were determined in peri-infarct tissue following photothrombotic motor cortex stroke. (R)-4-amino-cyclopent-1-enyl butylphosphinic acid (R)-4-ACPBPA and (S)-4-ACPBPA were assessed using 2-elecotrode voltage electrophysiology in Xenopus laevis oocytes. Stroke mice were treated for 4 weeks with either vehicle, the α5-selective negative allosteric modulator, L655,708, or the ρ1/2 antagonists, (R)-4-ACPBPA and (S)-4-ACPBPA respectively from 3 days post-stroke. Infarct size and expression levels of GAT3 and reactive astrogliosis were determined using histochemistry and immunohistochemistry respectively, and motor function was assessed using both the grid-walking and cylinder tasks. After stroke, significant increases in ρ1 and ρ2 mRNAs were observed on day 3, with ρ2 showing a further increase on day 7. (R)- and (S)-4-ACPBPA are both potent antagonists at ρ2 and only weak inhibitors of α5β2γ2 receptors. Treatment with either L655,708, (S)-4-ACPBPA (ρ1/2 antagonist; 5 mM only), or (R)-4-ACPBPA (ρ2 antagonist; 2.5 and 5 mM) from 3 days after stroke resulted in a significant improvement in motor recovery on the grid-walking task, with L655,708 and (R)-4-ACPBPA also showing an improvement in the cylinder task. Infarct size was unaffected, and only (R)-4-ACPBPA significantly increased peri-infarct GAT3 expression and decreased the level of reactive astrogliosis. Importantly, inhibiting GABAC receptors affords significant improvement in motor function after stroke. Targeting the ρ-subunit could provide a novel delayed treatment option for stroke recovery. [ABSTRACT FROM AUTHOR]

Stroke remains a leading cause of adult disability with treatments limited to thrombolytic therapies that are severely limited by a narrow therapeutic window. The potential of hundreds of other therapeutic agents cannot be evaluated due to their poor ability to cross the blood-brain barrier. Recently, biopolymer hydrogels have shown promise at overcoming these obstacles via the delivering of therapeutic molecules (pharmacological, mRNA, stem cells, etc.) to injured nervous tissue to afford functional recovery in rodent models of stroke. To date, we have tested different biopolymer hydrogels in mouse models of stroke for their ability to promote post-stroke recovery and for in situ delivery of growth factors, small pharmacological compounds, siRNAs, and stem cells. Here, we describe practical instructions on how to prepare various biopolymer hydrogels in house with further guidance on how to use them for intracerebral administration of therapeutic agents in preclinical stroke models., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)