Sulfur dioxide inhibits vascular smooth muscle cell proliferation via suppressing the Erk/MAP kinase pathway mediated by cAMP/PKA signaling.
The present study was designed to investigate the role of endogenous sulfur dioxide (SO2) 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 SO2 inhibited VSMC proliferation by preventing cell cycle progression from G1 to S phase and by reducing DNA synthesis. SO2 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 SO2 suppressed serum-induced VSMC proliferation. However, annexin V-propidium iodide (PI) staining and cell cycle analysis demonstrated that SO2 did not influence VSMC apoptosis in the serum-induced proliferation model. In a platelet-derived growth factor (PDGF)-BB-stimulated VSMC proliferation model, SO2 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 SO2 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 SO2 could stimulate the cAMP/PKA pathway to block c-Raf activation, whereas the Ser259 site on c-Raf had an important role in SO2-induced suppression of Erk/MAPK pathway. The present study firstly demonstrated that SO2 exerted a negative regulation of VSMC proliferation via suppressing the Erk/MAPK pathway mediated by cAMP/PKA signaling.
Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China.
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Liu
Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China.
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Huang
Central Laboratory, Peking University First Hospital, Beijing, People's Republic of China.
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Bu
Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
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Liu
Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
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Holmberg
Centre of Medical and Health Analysis, Peking University Health Science Center, Beijing, People's Republic of China.
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Jia
1] Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, People's Republic of China [2] Key Laboratory of Molecular Cardiology, Ministry of Education, Beijing, People's Republic of China.
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Tang
1] Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China [2] Key Laboratory of Molecular Cardiology, Ministry of Education, Beijing, People's Republic of China.
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Du
Department of Pediatrics, Peking University First Hospital, Beijing, People's Republic of China.
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Jin
D000818:Animals; D001219:Aspartate Aminotransferases / Q000235:genetics / Q000378:metabolism; D000077214:Becaplermin; D049109:Cell Proliferation / Q000187:drug effects*; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D010766:Phosphorylation; D000090063:Proto-Oncogene Mas; D019908:Proto-Oncogene Proteins c-raf; D020574:Proto-Oncogene Proteins c-sis / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D013458:Sulfur Dioxide / Q000494:pharmacology*; D013997:Time Factors; D014162:Transfection
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D020574:Proto-Oncogene Proteins c-sis; D013458:Sulfur Dioxide; D000077214:Becaplermin; D000242:Cyclic AMP; D001219:Aspartate Aminotransferases; D019908:Proto-Oncogene Proteins c-raf; C546782:Raf1 protein, rat; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; D048369:MAP Kinase Kinase 1