biostudies-literatureAkande ANIGMS NIH HHSNIH HHS94https://www.ebi.ac.uk/biostudies/studies/S-EPMC12487352biostudies-literatureUnknown22(1)Neurogranin (Ng), a known regulator of neuronal Ca²⁺-calmodulin (CaM) signaling, is linked to Alzheimer's disease. Though well-studied in neurons, Ng is also expressed in brain vasculature, where its function remains unclear. To investigate Ng's role in brain microvascular endothelial cells, we defined its interactome using immunoprecipitation-mass spectrometry (IP-MS) under high- and low-Ca²⁺ conditions. Among 119 Ng-binding proteins, we discovered a novel interaction between Ng and MYH9, a key regulator of cytoskeletal remodeling. Ng-MYH9 binding was prominent in high Ca²⁺ and validated via CaM affinity pulldown and proximity ligation assays. Ng knockdown reduced F-actin levels, while MYH9 knockdown decreased both Ng and F-actin. Loss of Ng-MYH9 also impaired AKT-GSK3β signaling and elevated the endothelial activation marker VCAM1. Ng-null mice exhibited disrupted brain microvascular architecture and reduced MYH9 expression in endothelial cells. These findings reveal a novel Ng pathway promoting MYH9-dependent cytoskeletal remodeling and a potential role in maintaining blood-brain barrier integrity, a previously unrecognized function for Ng in brain health and Alzheimer's disease.Fluids and barriers of the CNSNeurogranin-MYH9 interaction regulates cytoskeletal remodeling in cerebral vasculature.PMC12487352P20GM121307P20 GM134974P20 GM121307Park JEAkande AScott RNam HWAlexander JSfalseNeurogranin-MYH9 interaction regulates cytoskeletal remodeling in cerebral vasculature.Neurogranin (Ng), a known regulator of neuronal Ca²⁺-calmodulin (CaM) signaling, is linked to Alzheimer's disease. Though well-studied in neurons, Ng is also expressed in brain vasculature, where its function remains unclear. To investigate Ng's role in brain microvascular endothelial cells, we defined its interactome using immunoprecipitation-mass spectrometry (IP-MS) under high- and low-Ca²⁺ conditions. Among 119 Ng-binding proteins, we discovered a novel interaction between Ng and MYH9, a key regulator of cytoskeletal remodeling. Ng-MYH9 binding was prominent in high Ca²⁺ and validated via CaM affinity pulldown and proximity ligation assays. Ng knockdown reduced F-actin levels, while MYH9 knockdown decreased both Ng and F-actin. Loss of Ng-MYH9 also impaired AKT-GSK3β signaling and elevated the endothelial activation marker VCAM1. Ng-null mice exhibited disrupted brain microvascular architecture and reduced MYH9 expression in endothelial cells. These findings reveal a novel Ng pathway promoting MYH9-dependent cytoskeletal remodeling and a potential role in maintaining blood-brain barrier integrity, a previously unrecognized function for Ng in brain health and Alzheimer's disease.2025-01-01T00:00:00Z2025 Sep2026-06-04T01:48:45.681Z2026-05-04T03:13:57.996ZS-EPMC124873524102942610.1186/s12987-025-00709-x