Sprouty1 inhibits angiogenesis in association with up-regulation of p21 and p27.
Sprouty1 (Spry1) is a conserved antagonist of FGF signaling. The goal of this study was to further explore the downstream mechanisms governing Spry1 inhibition of endothelial cell proliferation. Up-regulation of Spry1 in HUVECs inhibited tube formation on Matrigel (n = 6, P < 0.001). This was associated with decreased proliferation as measured by BrdU incorporation (n = 6, P < 0.001) and increased protein expression of the cyclin-dependent kinase inhibitor 1A (CDKN1A), p21 and cyclin-dependent kinase inhibitor 1B (CDKN1B), p27. A transcriptional analysis using a targeted human angiogenesis array following up-regulation of Spry1 demonstrated a >2-fold increase in an anti-angiogenic factor, serpin peptidase inhibitor, clad F (Serpinf1), and a >2-fold decrease in pro-angiogenic factors fms-related tyrosine kinase 1 (FLT1), angiopoietin2 (Ang-2), and placental growth factor (PGF) (n = 2). To define upstream mechanisms that may regulate endogenous Spry1, we performed a search for responsive elements upstream of the promoter region. This search resulted in the identification of multiple degenerate hypoxia responsive elements. Exposure to hypoxia resulted in a significant increase in Spry1 expression (n = 8, P < 0.01). These findings shed new light on downstream signaling pathways associated with Spry1 anti-proliferative responses, and provide new evidence that hypoxia stimulates Spry1 expression.
Lee
Sangjin
S
Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, USA.
Bui Nguyen
Tri M
TM
Kovalenko
Dmitry
D
Adhikari
Neeta
N
Grindle
Suzanne
S
Polster
Sean P
SP
Friesel
Robert
R
Ramakrishnan
Sundaram
S
Hall
Jennifer L
JL
D049109:Cell Proliferation; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018919:Neovascularization, Physiologic; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation
D050759:Cyclin-Dependent Kinase Inhibitor p21; D008565:Membrane Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C486055:SPRY1 protein, human; D050760:Cyclin-Dependent Kinase Inhibitor p27