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Activation of Cyclic AMP‐Dependent Protein Kinase in Okadaic Acid‐Treated Neurons Potentiates Neurofilament Fragmentation and Stimulates Phosphorylation of Ser 2 in the Low‐Molecular‐Mass Neurofilament Subunit
Author(s) -
Giasson Benoit I.,
Cromlish James A.,
Athlan Eric S.,
Mushynski Walter E.
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.66031207.x
Subject(s) - dephosphorylation , phosphorylation , okadaic acid , neurofilament , protein subunit , phosphatase , phosphoserine , phosphopeptide , protein kinase a , biochemistry , chemistry , protein phosphatase 1 , protein phosphorylation , microbiology and biotechnology , kinase , biology , serine , immunohistochemistry , gene , immunology
The activation of cyclic AMP‐dependent protein kinase (PKA) in rat dorsal root ganglion (DRG) cultures increased phosphorylation of the low‐molecular‐mass neurofilament subunit (NFL) at a site previously identified as Ser 55 but had no effect on neurofilament integrity. When PKA was activated in DRG cultures treated with 20–250 n M okadaic acid, neurofilament fragmentation was enhanced, and there was a corresponding increase in phosphorylation of NFL at a novel site. This site was also phosphorylated by PKA in vitro and was determined to be Ser 2 by mass spectrometric analysis of the purified chymotryptic phosphopeptide. The PKA sites in NFL were dephosphorylated by the purified catalytic subunit of protein phosphatase‐2A but not that of protein phosphatase‐1, and phosphoserine‐2 was a better substrate than phosphoserine‐55. The phosphorylation and dephosphorylation of Ser 2 and Ser 55 in NFL may therefore be involved in the modulation of neurofilament dynamics through the antagonistic effects of PKA and protein phosphatase‐2A.