GHB analogs confer neuroprotection through specific interaction with the CaMKIIα hub domain

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 31; p. 1
• Main Authors: Leurs, Ulrike, Klein, Anders B, McSpadden, Ethan D, Griem-Krey, Nane, Solbak, Sara M Ø, Houlton, Josh, Villumsen, Inge S, Vogensen, Stine B, Hamborg, Louise, Gauger, Stine J, Palmelund, Line B, Larsen, Anne Sofie G, Shehata, Mohamed A, Kelstrup, Christian D, Olsen, Jesper V, Bach, Anders, Burnie, Robert O, Kerr, D Steven, Gowing, Emma K, Teurlings, Selina M W, Chi, Chris C, Gee, Christine L, Frølund, Bente, Kornum, Birgitte R, van Woerden, Geeske M, Clausen, Rasmus P, Kuriyan, John, Clarkson, Andrew N, Wellendorph, Petrine
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 03.08.2021
• Subjects: Analogs; BASIC BIOLOGICAL SCIENCES; Binding Sites; Biological Sciences; Ca2+/calmodulin-dependent protein kinase II; Calcium ions; Calcium-binding protein; Calcium-Calmodulin-Dependent Protein Kinase Type 2 - genetics; Calcium-Calmodulin-Dependent Protein Kinase Type 2 - metabolism; Calmodulin; Carboxylic Acids - pharmacology; Chemical compounds; Crystal structure; Crystallography, X-Ray; Cyclopentanes - pharmacology; Domains; Excitotoxicity; Gene Expression Regulation, Enzymologic - drug effects; HEK293 Cells; HOCPCA; Humans; Ischemia; Kinases; Ligands; Neuroprotection; Oligomers; Pharmacology; Photoaffinity labeling; photothrombotic stroke; Protein Binding; Protein Domains; Proteins; Proteomics; Signal Transduction; Sodium Oxybate - metabolism; Therapeutic targets; Thermal stability; x-ray crystallography; γ-Hydroxybutyric acid; x-ray crystallography; photoaffinity labeling; excitotoxicity; photothrombotic stroke; HOCPCA
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2108079118

Ca /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.