Identification and functional analysis of endothelial tip cell-enriched genes.
Sprouting of developing blood vessels is mediated by specialized motile endothelial cells localized at the tips of growing capillaries. Following behind the tip cells, endothelial stalk cells form the capillary lumen and proliferate. Expression of the Notch ligand Delta-like-4 (Dll4) in tip cells suppresses tip cell fate in neighboring stalk cells via Notch signaling. In DLL4(+/-) mouse mutants, most retinal endothelial cells display morphologic features of tip cells. We hypothesized that these mouse mutants could be used to isolate tip cells and so to determine their genetic repertoire. Using transcriptome analysis of retinal endothelial cells isolated from DLL4(+/-) and wild-type mice, we identified 3 clusters of tip cell-enriched genes, encoding extracellular matrix degrading enzymes, basement membrane components, and secreted molecules. Secreted molecules endothelial-specific molecule 1, angiopoietin 2, and apelin bind to cognate receptors on endothelial stalk cells. Knockout mice and zebrafish morpholino knockdown of apelin showed delayed angiogenesis and reduced proliferation of stalk cells expressing the apelin receptor APJ. Thus, tip cells may regulate angiogenesis via matrix remodeling, production of basement membrane, and release of secreted molecules, some of which regulate stalk cell behavior.
del Toro
Raquel
R
Inserm U833, Paris, France.
Prahst
Claudia
C
Mathivet
Thomas
T
Siegfried
Geraldine
G
Kaminker
Joshua S
JS
Larrivee
Bruno
B
Breant
Christiane
C
Duarte
Antonio
A
Takakura
Nobuyuki
N
Fukamizu
Akiyoshi
A
Penninger
Josef
J
Eichmann
Anne
A
D048868:Adaptor Proteins, Signal Transducing; D054392:Adipokines; D000818:Animals; D000073861:Apelin; D000075244:Apelin Receptors; D002135:Calcium-Binding Proteins; D002196:Capillaries / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D020869:Gene Expression Profiling; D057895:Haploinsufficiency; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D005810:Multigene Family; D018919:Neovascularization, Physiologic / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D043562:Receptors, G-Protein-Coupled / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D012171:Retinal Vessels / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D015027:Zebrafish
D048868:Adaptor Proteins, Signal Transducing; D054392:Adipokines; D000073861:Apelin; D000075244:Apelin Receptors; C402826:Apln protein, mouse; C491285:Aplnr protein, mouse; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; C519665:DLL4 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D043562:Receptors, G-Protein-Coupled; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases