Sulfur dioxide inhibits vascular smooth muscle cell proliferation via suppressing the Erk/MAP kinase pathway mediated by cAMP/PKA signaling

• Published in: Cell death & disease Vol. 5; no. 5; p. e1251
• Main Authors: Liu, D, Huang, Y, Bu, D, Liu, A D, Holmberg, L, Jia, Y, Tang, C, Du, J, Jin, H
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22-05-2014; Springer Nature B.V; Nature Publishing Group
• Subjects: 631/136/2091; 631/80/86; Animals; Antibodies; Aspartate Aminotransferases - genetics; Aspartate Aminotransferases - metabolism; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell Culture; Cell Proliferation - drug effects; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Dose-Response Relationship, Drug; Down-Regulation; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases - metabolism; G1 Phase Cell Cycle Checkpoints - drug effects; HEK293 Cells; Humans; Immunology; Life Sciences; MAP Kinase Kinase 1 - genetics; MAP Kinase Kinase 1 - metabolism; MAP Kinase Kinase Kinases - metabolism; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - enzymology; Muscle, Smooth, Vascular - pathology; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - enzymology; Myocytes, Smooth Muscle - pathology; Original; original-article; Phosphorylation; Proto-Oncogene Proteins c-raf; Proto-Oncogene Proteins c-sis - metabolism; Rats; RNA Interference; SAMHÄLLSVETENSKAP; Signal Transduction - drug effects; SOCIAL SCIENCES; Sulfur Dioxide - pharmacology; Time Factors; Transfection; sulfur dioxide; Erk/MAP kinase; vascular smooth muscle cell; proliferation; cAMP/PKA
• ISSN: 2041-4889; 2041-4889
• DOI: 10.1038/cddis.2014.229

The present study was designed to investigate the role of endogenous sulfur dioxide (SO
2
) in vascular smooth muscle cell (VSMC) proliferation, and explore the possible role of cross-talk between cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and extracellular signal-regulated kinase (Erk)/mitogen-activated protein kinase (MAPK) pathways in this action. By cell counting, growth curve depict, flow cytometry and bromodeoxyuridine (BrdU) labeling assays, we found that SO
2
inhibited VSMC proliferation by preventing cell cycle progression from G1 to S phase and by reducing DNA synthesis. SO
2
synthase aspartate aminotransferase (AAT1 and AAT2) overexpression significantly inhibited serum-induced proliferating cell nuclear antigen (PCNA) protein expression in VSMCs, demonstrated by western blot analysis. Moreover, overexpression of AAT1 or AAT2 markedly reduced incorporation of BrdU in serum-treated VSMCs. By contrast, either AAT1 or AAT2 knockdown significantly exacerbated serum-stimulated VSMC proliferation. Thus, both exogenous- and endogenous-derived SO
2
suppressed serum-induced VSMC proliferation. However, annexin V-propidium iodide (PI) staining and cell cycle analysis demonstrated that SO
2
did not influence VSMC apoptosis in the serum-induced proliferation model. In a platelet-derived growth factor (PDGF)-BB-stimulated VSMC proliferation model, SO
2
dephosphorylated the active sites of Erk1/2, MAPK kinase 1/2 and RAF proto-oncogene serine/threonine-protein kinase (c-Raf) induced by PDGF-BB. However, the inactivation of the three kinases of the Erk/MAPK pathway was not due to the separate interferences on them by SO
2
simultaneously, but a consequence of the influence on the upstream activity of the c-Raf molecule. Hence, we examined the cAMP/PKA pathway, which could inhibit Erk/MAPK transduction in VSMCs. The results showed that SO
2
could stimulate the cAMP/PKA pathway to block c-Raf activation, whereas the Ser259 site on c-Raf had an important role in SO
2
-induced suppression of Erk/MAPK pathway. The present study firstly demonstrated that SO
2
exerted a negative regulation of VSMC proliferation via suppressing the Erk/MAPK pathway mediated by cAMP/PKA signaling.