JNK phosphorylates Ser332 of doublecortin and regulates its function in neurite extension and neuronal migration

Junghee Jin, Hiromi Suzuki, Syu Ichi Hirai, Katsuhiko Mikoshiba, Toshio Ohshima

    Research output: Contribution to journalArticle

    22 Citations (Scopus)

    Abstract

    Doublecortin (DCX) is expressed in young neurons and functions as a microtubule-associated protein. DCX is essential for neuronal migration because humans with mutations in the DCX gene exhibit cortical lamination defects known as lissencephaly in males and subcortical laminar heterotopia (or double cortex syndrome) in females. Phosphorylation of DCX alters its affinity for tubulin and may modulate neurite extension and neuronal migra tion. Previous in vitro phosphorylation experiments revealed that cyclin-dependent kinase 5 (Cdk5) phosphorylates multiple sites of DCX, including Ser332, (S332). However, phosphorylation at only Ser297 has been shown in vivo. In the present study, we examined phosphorylation of S332 of DCX in the Cdk5-/- mouse brain and results found, unexpectedly, indicate an increased DCX phosphorylation at S332. We found that JNK, not Cdk5, phosphorylates DCX at S332 in vivo. To examine the physiological significance of S332 phosphorylation of DCX in neuronal cells, we transfected cells with either GFP, GFP-DCX-WT, or GFP-DCX-S332A and analyzed neurite extension and migration. Introduction of GFP-DCX-WT enhanced neurite extension and migration. These effects of DCX introduction were suppressed when we used GFP-DCX-S332A. Treatment of neurons with JNK inhibitor increased the amount of DCX that bound to tubulin. Interestingly, amount of DCX that bound to tubulin decreased in Cdk5-/- brain homogenates, which indicates that phosphorylation of DCX by JNK is critical for the regulation of DCX binding to tubulin. These results suggest the physiological importance of phosphorylation of DCX for its function.

    Original languageEnglish
    Pages (from-to)929-942
    Number of pages14
    JournalDevelopmental Neurobiology
    Volume70
    Issue number14
    DOIs
    Publication statusPublished - 2010

    Fingerprint

    Neurites
    Phosphorylation
    Cyclin-Dependent Kinase 5
    Tubulin
    Classical Lissencephalies and Subcortical Band Heterotopias
    Lissencephaly
    Neurons
    Microtubule-Associated Proteins
    Brain
    Mutation
    Genes

    Keywords

    • Cdk5
    • Doublecortin
    • JNK
    • Neurite extension
    • Neuronal migration
    • Phosphorylation

    ASJC Scopus subject areas

    • Cellular and Molecular Neuroscience
    • Developmental Neuroscience

    Cite this

    JNK phosphorylates Ser332 of doublecortin and regulates its function in neurite extension and neuronal migration. / Jin, Junghee; Suzuki, Hiromi; Hirai, Syu Ichi; Mikoshiba, Katsuhiko; Ohshima, Toshio.

    In: Developmental Neurobiology, Vol. 70, No. 14, 2010, p. 929-942.

    Research output: Contribution to journalArticle

    Jin, Junghee ; Suzuki, Hiromi ; Hirai, Syu Ichi ; Mikoshiba, Katsuhiko ; Ohshima, Toshio. / JNK phosphorylates Ser332 of doublecortin and regulates its function in neurite extension and neuronal migration. In: Developmental Neurobiology. 2010 ; Vol. 70, No. 14. pp. 929-942.
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    abstract = "Doublecortin (DCX) is expressed in young neurons and functions as a microtubule-associated protein. DCX is essential for neuronal migration because humans with mutations in the DCX gene exhibit cortical lamination defects known as lissencephaly in males and subcortical laminar heterotopia (or double cortex syndrome) in females. Phosphorylation of DCX alters its affinity for tubulin and may modulate neurite extension and neuronal migra tion. Previous in vitro phosphorylation experiments revealed that cyclin-dependent kinase 5 (Cdk5) phosphorylates multiple sites of DCX, including Ser332, (S332). However, phosphorylation at only Ser297 has been shown in vivo. In the present study, we examined phosphorylation of S332 of DCX in the Cdk5-/- mouse brain and results found, unexpectedly, indicate an increased DCX phosphorylation at S332. We found that JNK, not Cdk5, phosphorylates DCX at S332 in vivo. To examine the physiological significance of S332 phosphorylation of DCX in neuronal cells, we transfected cells with either GFP, GFP-DCX-WT, or GFP-DCX-S332A and analyzed neurite extension and migration. Introduction of GFP-DCX-WT enhanced neurite extension and migration. These effects of DCX introduction were suppressed when we used GFP-DCX-S332A. Treatment of neurons with JNK inhibitor increased the amount of DCX that bound to tubulin. Interestingly, amount of DCX that bound to tubulin decreased in Cdk5-/- brain homogenates, which indicates that phosphorylation of DCX by JNK is critical for the regulation of DCX binding to tubulin. These results suggest the physiological importance of phosphorylation of DCX for its function.",
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    AU - Jin, Junghee

    AU - Suzuki, Hiromi

    AU - Hirai, Syu Ichi

    AU - Mikoshiba, Katsuhiko

    AU - Ohshima, Toshio

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    N2 - Doublecortin (DCX) is expressed in young neurons and functions as a microtubule-associated protein. DCX is essential for neuronal migration because humans with mutations in the DCX gene exhibit cortical lamination defects known as lissencephaly in males and subcortical laminar heterotopia (or double cortex syndrome) in females. Phosphorylation of DCX alters its affinity for tubulin and may modulate neurite extension and neuronal migra tion. Previous in vitro phosphorylation experiments revealed that cyclin-dependent kinase 5 (Cdk5) phosphorylates multiple sites of DCX, including Ser332, (S332). However, phosphorylation at only Ser297 has been shown in vivo. In the present study, we examined phosphorylation of S332 of DCX in the Cdk5-/- mouse brain and results found, unexpectedly, indicate an increased DCX phosphorylation at S332. We found that JNK, not Cdk5, phosphorylates DCX at S332 in vivo. To examine the physiological significance of S332 phosphorylation of DCX in neuronal cells, we transfected cells with either GFP, GFP-DCX-WT, or GFP-DCX-S332A and analyzed neurite extension and migration. Introduction of GFP-DCX-WT enhanced neurite extension and migration. These effects of DCX introduction were suppressed when we used GFP-DCX-S332A. Treatment of neurons with JNK inhibitor increased the amount of DCX that bound to tubulin. Interestingly, amount of DCX that bound to tubulin decreased in Cdk5-/- brain homogenates, which indicates that phosphorylation of DCX by JNK is critical for the regulation of DCX binding to tubulin. These results suggest the physiological importance of phosphorylation of DCX for its function.

    AB - Doublecortin (DCX) is expressed in young neurons and functions as a microtubule-associated protein. DCX is essential for neuronal migration because humans with mutations in the DCX gene exhibit cortical lamination defects known as lissencephaly in males and subcortical laminar heterotopia (or double cortex syndrome) in females. Phosphorylation of DCX alters its affinity for tubulin and may modulate neurite extension and neuronal migra tion. Previous in vitro phosphorylation experiments revealed that cyclin-dependent kinase 5 (Cdk5) phosphorylates multiple sites of DCX, including Ser332, (S332). However, phosphorylation at only Ser297 has been shown in vivo. In the present study, we examined phosphorylation of S332 of DCX in the Cdk5-/- mouse brain and results found, unexpectedly, indicate an increased DCX phosphorylation at S332. We found that JNK, not Cdk5, phosphorylates DCX at S332 in vivo. To examine the physiological significance of S332 phosphorylation of DCX in neuronal cells, we transfected cells with either GFP, GFP-DCX-WT, or GFP-DCX-S332A and analyzed neurite extension and migration. Introduction of GFP-DCX-WT enhanced neurite extension and migration. These effects of DCX introduction were suppressed when we used GFP-DCX-S332A. Treatment of neurons with JNK inhibitor increased the amount of DCX that bound to tubulin. Interestingly, amount of DCX that bound to tubulin decreased in Cdk5-/- brain homogenates, which indicates that phosphorylation of DCX by JNK is critical for the regulation of DCX binding to tubulin. These results suggest the physiological importance of phosphorylation of DCX for its function.

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