VEGFR1 tyrosine kinase signaling promotes lymphangiogenesis as well as angiogenesis indirectly via macrophage recruitment.
OBJECTIVE
Angiogenesis and lymphangiogenesis are complex phenomena that involve the interplay of several growth factors and receptors. Recently, we have demonstrated that in Keratin-14 (K14) promoter-driven Vegf-A transgenic (Tg) mice, not only angiogenesis but also lymphangiogenesis is stimulated. However, the mechanism by which VEGFR1 is involved in lymphangiogenesis remains unclear.


RESULTS
To examine how important the tyrosine kinase (TK) of VEGFR1 is in lymphangiogenesis in K14 Vegf-A Tg mice, we crossed the K14 Vegf-A Tg mice with VEGFR1-TK-deficient mice to generate double mutant K14 Vegf-A Tg Vegfr1 tk(-/-) mice. K14 Vegf-A Tg Vegfr1 tk(-/-) mice exhibit a remarkable decrease in lymphangiogensis as well as angiogenesis in subcutaneous tissues. To address the mechanism underlying the decrease in lymphangiogensis, we investigated the recruitment of monocyte-macrophage-lineage cells into the skin. The recruitment of VEGFR1-expressing macrophages driven by VEGF-A was reduced in K14 Vegf-A Tg Vegfr1 tk(-/-) mice. Vegf-A Tg mice that received VEGFR1-TK-deficient bone marrow showed a reduction of macrophage recruitment, lymphangiogenesis and angiogenesis compared with those in K14 Vegf-A Tg mice.


CONCLUSIONS
VEGFR1 signaling promotes lymphangiogenesis as well as angiogenesis mainly by increasing bone marrow-derived macrophage recruitment.
Murakami
Masato
M
Division of Genetics, Institute of Medical Science, University of Tokyo, Japan.
Zheng
Yujuan
Y
Hirashima
Masanori
M
Suda
Toshio
T
Morita
Yohei
Y
Ooehara
Jun
J
Ema
Hideo
H
Fong
Guo-Hua
GH
Shibuya
Masabumi
M
D000818:Animals; D016026:Bone Marrow Transplantation; D002199:Capillary Permeability / Q000502:physiology; D005260:Female; D042583:Lymphangiogenesis / Q000502:physiology*; D008264:Macrophages / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000502:physiology; D042582:Vascular Endothelial Growth Factor C / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D042461:Vascular Endothelial Growth Factor A; D042582:Vascular Endothelial Growth Factor C; C467480:vascular endothelial growth factor A, mouse; C467483:vascular endothelial growth factor C, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1