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J Neurosci September 11, 2013; 33 (37): 14666-80.

c-Jun N-terminal kinase phosphorylation of heterogeneous nuclear ribonucleoprotein K regulates vertebrate axon outgrowth via a posttranscriptional mechanism.

c-Jun N-terminal kinase (JNK) mediates cell signaling essential for axon outgrowth, but the associated substrates and underlying mechanisms are poorly understood. We identified in Xenopus laevis embryos a novel posttranscriptional mechanism whereby JNK regulates axonogenesis by phosphorylating a specific site on heterogeneous nuclear ribonucleoprotein K (hnRNP K). Both JNK inhibition and hnRNP K knockdown inhibited axon outgrowth and translation of hnRNP K-regulated cytoskeletal RNAs (tau and neurofilament medium), effects that were alleviated by expressing phosphomimetic, but not phosphodeficient, forms of hnRNP K. Immunohistochemical and biochemical analyses indicated that JNK phosphorylation of hnRNP K occurred within the cytoplasm and was necessary for the translational initiation of hnRNP K-targeted RNAs but not for hnRNP K intracellular localization or RNA binding. Thus, in addition to its known roles in transcription and cytoskeletal organization, JNK acts posttranscriptionally through hnRNP K to regulate translation of proteins crucial for axonogenesis.

PubMed ID: 24027268
PMC ID: PMC6705169
Article link: J Neurosci

Species referenced: Xenopus laevis
Genes referenced: dio3 gnl3 hnrnpc hnrnpk igf2bp3 jun mapk1 mapk8 mapt nefm prph sst.1
Antibodies: Nuclear Lamins 2/3 Ab1
Morpholinos: hnrnpk MO1

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References [+] :
Allison, Two distinct Staufen isoforms in Xenopus are vegetally localized during oogenesis. 2004, Pubmed, Xenbase