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PDE3A Deletion Suppresses Mouse VSMC Proliferation via Inhibition of MAPK Signaling and Cell Cycle Arrest
Author(s) -
Begum Najma,
Hockman Steven,
manganiello Vincent C
Publication year - 2011
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.25.1_supplement.39.6
Subject(s) - microbiology and biotechnology , mapk/erk pathway , cell growth , cell cycle , cell cycle checkpoint , chemistry , signal transduction , cell , biology , biochemistry
Phosphodiesterase type 3 (PDE3) is an important regulator of cAMP‐mediated responses within the cardiovascular system. However, the function and role of PDE3A and PDE3B isoforms in VSMC growth regulation are largely unclear. In this study, we examined the role of PDE3A and PDE3B in mechanisms for regulation of PDGF‐induced VSMC growth. Cultured VSMCs expanded from the aortas of PDE3A deficient mice (PDE3A−/−) exhibited >80% inhibition of PDGF‐induced DNA synthesis when compared to VSMCs from PDE3A WT type (PDE3A+/+) or PDE3B deficient (PDE3B−/−) mice (p<0.05). The growth inhibition was due to cell cycle arrest at G0/G1 phase, via selective inhibition of ERK phosphorylation due to increased site‐specific Raf‐1 ser259 inhibitory phosphorylation as well as excessive dephosphorylation of ERKs by elevated MAPK phosphatase 1 (MKP‐1). In contrast, the PI3‐kinase/Akt arm of PDGF signaling is preserved in PDE3A−/− VSMCs. PDE3A−/− VSMCs exhibited 2 ‐fold increase in basal PKA activity, upregulation of CREB and p53 proteins/phosphorylation, and elevated p21 expression, together with marked reduction of cyclin D1 levels and Rb phosphorylation. Adenoviral infection with inactive CREB partially restored growth effects in PDE3A−/− VSMCs. In contrast, exposure of PDE3A+/+ VSMCs to active CREB was associated with inhibition of cell growth, similar to PDE3A−/− VSMCs. Transfection of PDE3A−/− VSMCs with p53 siRNA diminished p21 and MKP‐1 and completely restored growth, without affecting cyclin D1 and Rb phosphorylation. We conclude that PDE3A regulates VSMC growth via two complimentary signaling pathways, p53 as well as PKA‐CREB, by predominantly modulating p21, MKP‐1, ERK signaling, and as well as G0/G1 cell cycle proteins such as cyclin D1 and Rb phosphorylation.