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Ceramide Recruits and Activates PKCzeta Within Structured Microdomains
Author(s) -
O'Neill Sean Michael,
Nagarajan M.,
Fox T.,
Houck K.,
Stover T.,
Unal O.,
Yun J.,
Naides S.,
Kester M.
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.a1121-a
Subject(s) - ceramide , microbiology and biotechnology , lipid signaling , protein kinase c , vascular smooth muscle , lipid raft , protein kinase b , phosphorylation , chemistry , biology , signal transduction , apoptosis , endocrinology , biochemistry , receptor , smooth muscle
We have previously demonstrated that C 6 ‐ceramide, an anti‐mitogenic cell‐permeable lipid metabolite, limits vascular smooth muscle growth by abrogating trauma‐induced AKT activity in a model of neointimal hyperplasia after balloon catheter stretch injury ( Charles et al., Circ Res 2000 ; 87 : 282 – 88 ). PKC zeta(ζ) was demonstrated to be a direct and selective target for ceramide, whose activation is necessary for suppression of AKT‐dependent mitogenesis ( Bourbon et al., J Biol Chem 2002 ; 277 : 3286 – 92 ). To further probe the interaction between ceramide and PKCζ, we investigated if ceramide localization within highly structured lipid‐microdomains or rafts leads to recruitment of ceramide‐binding targets such as PKCζ. Using rat aorta vascular smooth muscle cells (A7r5), we now demonstrate the intra‐membranous recruitment of activated, phosphorylated PKCζ 410 to ceramide‐enriched, caveolin‐containing, lipid microdomains. In addition, transfected myristoylated‐PKCζ accumulated within these microdomains. Pharmacological disruption of highly structured lipid microdomains resulted in abrogation of ceramide‐activated, PKCζ‐dependent AKT inactivation, while molecular strategies suggest that ceramide‐dependent PKCζ phosphorylation of Akt3 at Ser 34 was necessary for ceramide‐induced vascular smooth muscle cell growth arrest. Taken together, these data suggest that ceramide‐enriched structured microdomains are necessary for the PKCζ‐induced inactivation of Akt, as well as resultant vascular smooth muscle cell growth arrest.