CaMKII[beta]-mediated LIM-kinase activation plays a crucial role in BDNF-induced neuritogenesis

• Published in: Genes to cells : devoted to molecular & cellular mechanisms Vol. 18; no. 7; p. 533
• Main Authors: Saito, Akihiko, Miyajima, Ken, Akatsuka, Junichi, Kondo, Hiroshi, Mashiko, Toshiya, Kiuchi, Tai, Ohashi, Kazumasa, Mizuno, Kensaku
• Format: Journal Article
• Language: English
• Published: Tokyo Wiley Subscription Services, Inc 01.07.2013
• Subjects: Brain-derived neurotrophic factor; Cellular biology; Kinases; Proteins
• ISSN: 1356-9597; 1365-2443
• DOI: 10.1111/gtc.12054

LIM-kinase 1 (LIMK1) regulates actin cytoskeletal reorganization by phosphorylating and inactivating actin-depolymerizing factor and cofilin. We examined the role of LIMK1 in brain-derived neurotrophic factor (BDNF)-induced neuritogenesis in primary-cultured rat cortical neurons. Knockdown of LIMK1 or expression of a kinase-dead LIMK1 mutant suppressed BDNF-induced enhancement of primary neurite formation. By contrast, expression of an active form of LIMK1 promoted primary neuritogenesis in the absence of BDNF. BDNF-induced neuritogenesis was inhibited by KN-93, an inhibitor of Ca2+/calmodulin-dependent protein kinases (CaMKs), but not by STO-609, an inhibitor of CaMK-kinase (CaMKK). CaMKK activity is required for the activation of CaMKI and CaMKIV, but not CaMKII, which suggests that CaMKII is principally involved in BDNF-induced enhancement of neuritogenesis. Knockdown of CaMKII[beta], but not CaMKII[alpha], suppressed BDNF-induced neuritogenesis. Active CaMKII[beta] promoted neuritogenesis, and this promotion was inhibited by knockdown of LIMK1, indicating that CaMKII[beta] is involved in BDNF-induced neuritogenesis via activation of LIMK1. Furthermore, in vitro kinase assays revealed that CaMKII[beta] phosphorylates LIMK1 at Thr-508 in the kinase domain and activates the cofilin-phosphorylating activity of LIMK1. In summary, these results suggest that CaMKII[beta]-mediated activation of LIMK1 plays a crucial role in BDNF-induced enhancement of primary neurite formation. [PUBLICATION ABSTRACT]