Phosphorylation of zipcode binding protein 1 is required for brain-derived neurotrophic factor signaling of local beta-actin synthesis and growth cone turning.
The localization of specific mRNAs and their local translation in growth cones of developing axons has been shown to play an important mechanism to regulate growth cone turning responses to attractive or repulsive cues. However, the mechanism whereby local translation and growth cone turning may be controlled by specific mRNA-binding proteins is unknown. Here we demonstrate that brain-derived neurotrophic factor (BDNF) signals the Src-dependent phosphorylation of the beta-actin mRNA zipcode binding protein 1 (ZBP1), which is necessary for beta-actin synthesis and growth cone turning. We raised a phospho-specific ZBP1 antibody to Tyr396, which is a Src phosphorylation site, and immunofluorescence revealed BDNF-induced phosphorylation of ZBP1 within growth cones. The BDNF-induced increase in fluorescent signal of a green fluorescent protein translation reporter with the 3' untranslated region of beta-actin was attenuated with the Src family kinase-specific inhibitor PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine]. Furthermore, a nonphosphorylatable mutant, ZBP1 Y396F, suppressed the BDNF-induced and protein synthesis-dependent increase in beta-actin localization in growth cones. Last, the ZBP1 Y396F mutant blocked BDNF-induced attractive growth cone turning. These results indicate that phosphorylation of ZBP1 at Tyr396 within growth cones has a critical role to regulate local protein synthesis and growth cone turning. Our findings provide new insight into how the regulated phosphorylation of mRNA-binding proteins influences local translation underlying growth cone motility and axon guidance.
Sasaki
Yukio
Y
Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Welshhans
Kristy
K
Wen
Zhexing
Z
Yao
Jiaqi
J
Xu
Mei
M
Goshima
Yoshio
Y
Zheng
James Q
JQ
Bassell
Gary J
GJ
D000199:Actins / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D017404:In Situ Hybridization, Fluorescence; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014981:Xenopus
D000199:Actins; D019208:Brain-Derived Neurotrophic Factor; C498634:Igf2bp1 protein, rat; D012333:RNA, Messenger; D016601:RNA-Binding Proteins