Xenopus Dab2 is required for embryonic angiogenesis.
BACKGROUND
The molecular mechanisms governing the formation of the embryonic vascular system remain poorly understood. Here, we show that Disabled-2 (Dab2), a cytosolic adaptor protein, has a pivotal role in the blood vessel formation in Xenopus early embryogenesis.


RESULTS
Xenopus Disabled-2 (XDab2) is spatially localized to the blood vessels including the intersomitic veins (ISV) in early embryos. Both antisense morpholino oligonucleotide (MO)-mediated knockdown and overexpression of XDab2 inhibit the formation of ISV, which arise from angiogenesis. In addition, we found that activin-like signaling is essential for this angiogenic event. Functional assays in Xenopus animal caps reveal that activin-like signals induce VEGF expression and this induction can be inhibited by XDab2 depletion. However, XDab2 MO has no effects on the induction of other target genes by activin-like signals. Furthermore, we show that the disruption of the sprouting ISV in XDab2-depleted embryos can be rescued by coexpression of VEGF.


CONCLUSIONS
Taking together, we suggest that XDab2 regulates the embryonic angiogenesis by mediating the VEGF induction by activin-like signaling in Xenopus early development.
Cheong
Seong-Moon
SM
Division of Molecular and Life Sciences, Pohang University of Science and Technology, San 31, Hyoja Dong, Pohang, Kyungbuk, 790-784, Republic of Korea. tsetse77@postech.ac.kr <tsetse77@postech.ac.kr>
Choi
Sun-Cheol
SC
Han
Jin-Kwan
JK
D028341:Activins / Q000502:physiology; D000818:Animals; D004625:Embryo, Nonmammalian / Q000502:physiology*; D004627:Embryonic Induction / Q000502:physiology*; D018919:Neovascularization, Physiologic / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D029867:Xenopus Proteins / Q000096:biosynthesis* / Q000235:genetics; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
D029867:Xenopus Proteins; D028341:Activins