TY - JOUR
T1 - Sphingosine kinase 1 expression is regulated by signaling through PI3K, AKT2, and mTOR in human coronary artery smooth muscle cells
AU - Francy, Jacquelyn M.
AU - Nag, Arpita
AU - Conroy, Elizabeth J.
AU - Hengst, Jeremy A.
AU - Yun, Jong K.
N1 - Funding Information:
The authors would like to thank the Functional Genomics Core Facility at the Pennsylvania State College of Medicine for assistance with quantitative RT-PCR, Kruti Patel, Michael Guilford, Dr. B. Stanley of the Mass Spectrometry/Proteomics Core Facility for assistance with mass spectrometric analysis, and Drs. Bill Freeman, Mark Kester, Kent Vrana, Todd Fox, and Brian Reese for their advice and assistance. This study was funded in part by NIH grant CA 91155.
PY - 2007/4
Y1 - 2007/4
N2 - Sphingosine kinase 1 (SphK1) is a lipid kinase implicated in mitogenic signaling pathways in vascular smooth muscle cells. We demonstrate that human coronary artery smooth muscle (HCASM) cells require SphK1 for growth and that SphK1 mRNA and protein levels are elevated in PDGF stimulated HCASM cells. To determine the mechanism of PDGF-induced SphK1 expression, we used pharmacological inhibitors of the PI3K/AKT/mTOR signaling pathway. Wortmannin, SH-5, and rapamycin significantly blocked PDGF-stimulated induction of SphK1 mRNA and protein expression, indicating a regulatory role of the PI3K/AKT/mTOR pathway in SphK1 expression. To determine which isoform of AKT regulates SphK1 mRNA and protein levels, siRNAs specific for AKT1, AKT2, and AKT3 were used. We show that AKT2 siRNA significantly blocked PDGF-stimulated increases in SphK1 mRNA and protein expression levels as well as SphK1 enzymatic activity levels. In contrast, AKT1 or AKT3 siRNA did not have an effect. Together, these results demonstrate that the PI3K/AKT/mTOR signaling pathway is involved in regulation of SphK1, with AKT2 playing a key role in PDGF-induced SphK1 expression in HCASM cells.
AB - Sphingosine kinase 1 (SphK1) is a lipid kinase implicated in mitogenic signaling pathways in vascular smooth muscle cells. We demonstrate that human coronary artery smooth muscle (HCASM) cells require SphK1 for growth and that SphK1 mRNA and protein levels are elevated in PDGF stimulated HCASM cells. To determine the mechanism of PDGF-induced SphK1 expression, we used pharmacological inhibitors of the PI3K/AKT/mTOR signaling pathway. Wortmannin, SH-5, and rapamycin significantly blocked PDGF-stimulated induction of SphK1 mRNA and protein expression, indicating a regulatory role of the PI3K/AKT/mTOR pathway in SphK1 expression. To determine which isoform of AKT regulates SphK1 mRNA and protein levels, siRNAs specific for AKT1, AKT2, and AKT3 were used. We show that AKT2 siRNA significantly blocked PDGF-stimulated increases in SphK1 mRNA and protein expression levels as well as SphK1 enzymatic activity levels. In contrast, AKT1 or AKT3 siRNA did not have an effect. Together, these results demonstrate that the PI3K/AKT/mTOR signaling pathway is involved in regulation of SphK1, with AKT2 playing a key role in PDGF-induced SphK1 expression in HCASM cells.
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U2 - 10.1016/j.bbaexp.2007.03.005
DO - 10.1016/j.bbaexp.2007.03.005
M3 - Article
C2 - 17482291
AN - SCOPUS:34248219175
SN - 0167-4781
VL - 1769
SP - 253
EP - 265
JO - Biochimica et Biophysica Acta - Gene Structure and Expression
JF - Biochimica et Biophysica Acta - Gene Structure and Expression
IS - 4
ER -