Mitogenic signaling via platelet-derived growth factor beta in metanephric mesenchymal cells.
Mice deficient in either platelet-derived growth factor (PDGF) B chain or PDGF receptor (PDGFR) beta lack mesangial cells. PDGF stimulates proliferation and migration of metanephric mesenchymal cells, from which mesangial cells are derived. Binding of PDGF to PDGFR-beta induces autophosphorylation at specific tyrosine residues and activates various effector proteins, including phosphatidylinositol-3-kinase (PI3-K). This study explored the role of PI 3-K and reactive oxygen species (ROS) in PDGF-mediated signaling using cells established from wild-type and PDGFR-beta -/- metanephric blastemas at 11.5 days post-conception. PDGF-induced effects that were dependent on PI3-K activation were determined using PDGFR-beta -/- cells made to express "add-back" mutant PDGFR-beta capable of binding PI3-K. We found that PDGF is mitogenic for mesenchymal cells expressing PDGFR-beta, and PI3-K is an important regulator of PDGF-induced DNA synthesis. Activation of ERK1/2 is partially dependent on PI3-K, and both the PI3-K and MEK-ERK1/2 pathways contribute to PI3-K-dependent mitogenesis. In addition, PDGF-induced DNA synthesis in wild-type cells was found to be dependent on ROS that are generated downstream of PI3-K activation. Using antisense oligonucleotides and small interfering RNA, we determined that the NAD(P)H oxidase Nox4 produces these ROS that activate Akt and the MEK-ERK1/2 mitogenic cascade. In conclusion, the present study demonstrates Nox4 involvement in PDGF-induced DNA synthesis in metanephric mesenchymal cells and provides the first evidence that PDGF-induced PI3-K activity enhances production of ROS by Nox4.
Wagner
Brent
B
Division of Nephrology, Department of Medicine, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA. wagnerb@uthscsa.edu
Ricono
Jill M
JM
Gorin
Yves
Y
Block
Karen
K
Arar
Mazen
M
Riley
Dan
D
Choudhury
Goutam Ghosh
GG
Abboud
Hanna E
HE
D000818:Animals; D018929:Cell Culture Techniques; D007678:Kidney Glomerulus / Q000196:embryology*; D008648:Mesoderm / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D008938:Mitosis / Q000502:physiology; D019255:NADPH Oxidases / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
D010982:Platelet-Derived Growth Factor; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D020797:Receptor, Platelet-Derived Growth Factor beta