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Association of cAMP phosphodiesterase with microtubule binding proteins in pulmonary endothelium: the PKA‐mediated phosphorylation of Tau and MAP4
Author(s) -
Zhu Bing,
Creighton Judy,
Stevens Troy
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1164
Subject(s) - phosphorylation , forskolin , microbiology and biotechnology , microtubule , spectrin , phosphodiesterase , biology , chemistry , cytoskeleton , biochemistry , cell , receptor , enzyme
Phosphodiesterase 4D4 (PDE4D4) interacts with the SH3 domain of non‐erythroid spectrin in pulmonary microvascular endothelial cells (PMVECs), and compartmentalizes the cAMP signaling at cell‐cell junction regions. A retrovirus construct containing the N‐terminal SH3 binding domains of PDE4D4 1–116 was introduced into PMVECs. This construct converted the forskolin‐stimulated cAMP from a barrier enhancing to a barrier disrupting stimulus. To examine whether the dominant‐negative action of PDE4D4 1–116 allows cAMP to regulate cytoskeleton targets that are normally inaccessible, the phosphorylation of two microtubule binding proteins, Tau and MAP4, were tested using serine‐selective phosphorylation antibodies. The basal phosphorylation of Tau‐ser214 and MAP4‐ser768 were both increased in PDE4D4 1–116 cells as compared to the control cells. Unlike control cells, forskolin (1μM) enhanced the phosphorylation at 30 min in PDE4D4 1–116 expressing cells. PKA‐selective inhibitor H89 blocked the phosphorylation. Co‐immunoprecipitation of Tau‐ser214 with β‐tubulin was only observed in PDE4D4 1–116 cells; this co‐IP was enhanced by forskolin stimulation. Data suggest that the inhibition of the membrane associated PDE4D4 enhances phosphorylated Tau and MAP4 binding to microtubules. Since tau and MAP4 phosphorylation disrupts microtubules, current studies suggest PDE4D4 1–116 may allow cAMP to activate intracellular targets that result in microtubule disassembly in PMVECs. Supported by HL066299 and HL060024.