title: Alternative splicing in the variable domain of CaMKIIβ affects the level of F-actin association in developing neurons.
abstract: The Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII) β has an essential function in dendritic spines via binding to and reorganization of the actin cytoskeleton during plasticity events not shared by CaMKIIα isoform. CaMKIIβ and CaMKIIα isoforms have remarkable structural differences within the variable region. Three exons (E1, E3, and E4) are present in CaMKIIβ but not in CaMKIIα gene. Four splice variants of CaMKIIβ isoforms (CaMKIIβ, β', βe and β'e) were discovered in embryonic and adult brains. Exons E1 (lacked in βe and β'e) and E4 (lacked in β' and β'e) are subject to differential alternative splicing. We hypothesized that the sequences encoded by exons E1, E3, and/or E4 are involved in CaMKIIβ-specific bundling to the F-actin cytoskeleton. We tested the colocalization and association of these CaMKIIβ variants within an F-actin-rich structure (microspike) in CaMKIIα free embryonic day 18 (E-18) rat cortical neurons. Our results showed that CaMKIIβ and CaMKIIβ' containing exon E1 displayed an association with F-actin, while CaMKIIβe and CaMKIIβ'e lacking E1 did not. Moreover, CaMKIIβ' lacking exon E4 but having E1 showed decreased actin bindingcapacity compared to WT CaMKIIβ. This suggested E1 is required for the association between CaMKIIβ and F-actin, while E4 assists CaMKIIβ to associate with F-actin better. Thus, alternative splicing of CaMKIIβ variants in developing neurons may serve as a developmental switch for actin cytoskeleton-associated isoforms and therefore correlated with dendritic arborization and synapse formation during LTP.
authors.affiliation: Department of Rehabilitation, Zhongnan Hospital of Wuhan University Wuhan 430071, Hubei, China ; Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University Augusta, Georgia 30912, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University Augusta, Georgia 30912, USA.
authors.forename: Lori
authors.initials: L
authors.lastname: Redmond
authors.affiliation: Department of Neurosurgery, Zhongnan Hospital of Wuhan University Wuhan 430071, Hubei, China.
authors.forename: Chengshi
authors.initials: C
authors.lastname: Xu
authors.affiliation: Department of Plastic Surgery, Jinan Central Hospital Affiliated to Shandong University Jinan 250013, Shandong, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Kuang
authors.affiliation: Department of Rehabilitation, Zhongnan Hospital of Wuhan University Wuhan 430071, Hubei, China.
authors.forename: Weijing
authors.initials: W
authors.lastname: Liao
mesh_terms: D000199:Actins / Q000378:metabolism*; D017398:Alternative Splicing; D000818:Animals; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D005091:Exons; D036681:Fluorescence Recovery After Photobleaching; D015151:Immunoblotting; D007150:Immunohistochemistry; D055495:Neurogenesis / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D020033:Protein Isoforms; D051381:Rats; D020318:Rats, Long-Evans; D014162:Transfection
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; C581829:Camk2n1 protein, rat; D002352:Carrier Proteins; D020033:Protein Isoforms
keywords: CaMKIIβ; F-actin; FRAP; developing neuron