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Protein phosphatase 2A B56α mediates retinoic acid‐induced decreases in phosphorylation of endothelial nitric oxide synthase at serine 1179 and nitric oxide production
Author(s) -
Jo Inho,
Park JungHyun,
Sung Hye Youn,
Lee Jee Young,
Kim Hyun Jin,
Ahn JungHyuck
Publication year - 2013
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.27.1_supplement.1051.3
Subject(s) - protein phosphatase 2 , enos , phosphorylation , nitric oxide synthase type iii , okadaic acid , dephosphorylation , nitric oxide , serine , phosphatase , western blot , chemistry , nitric oxide synthase , endocrinology , medicine , biology , biochemistry , gene
All‐trans retinoic acid (atRA) decreases nitric oxide (NO) production through Akt‐mediated decreased phosphorylation of endothelial NO synthase at serine 1179 (eNOS‐Ser 1179 ) in bovine aortic endothelial cells (BAEC). Since protein phosphatase 2A (PP2A) was also reported to decrease eNOS‐Ser 1179 phosphorylation, we investigated using BAEC whether PP2A mediates atRA‐induced eNOS‐Ser 1179 dephosphorylation and subsequent decreased NO production. Treatment with okadaic acid (5 nM), a selective PP2A inhibitor, or ectopic expression of siRNA of PP2A catalytic subunit α (PP2A Cα) significantly increased eNOS‐Ser 1179 phosphorylation and NO production. Each treatment also significantly reversed atRA‐induced observed effects, suggesting a role for PP2A. We also found that atRA significantly increased cellular PP2A activity. However, western blot analysis revealed that atRA did not increase the expression of PP2A Cα, although it significantly increased the level of B56α of PP2A regulatory B subunit (PP2A B56α) but not PP2A B55α and PP2A B56δ. Real‐time PCR assay confirmed a significant increase in PP2A B56α mRNA expression in atRA‐treated cells. Ectopic expression of siRNA of PP2A B56α significantly reversed atRA‐induced inhibitory effects on eNOS‐Ser 1179 phosphorylation and NO production, suggesting a role for PP2A B56α. Our study demonstrates for the first time that atRA decreases eNOS‐Ser 1179 phosphorylation and NO release at least in part by increasing PP2A B56α‐mediated PP2A activity in BAEC. This study was supported by NRF 2012R1A2A2A01004914 and 2011–0027347.