P4: Role of Integrin-linked kinase (ILK) in VEGFR3 signaling and cardiovascular development
Background
Recently, a molecular mechanism has been proposed for aorta formation in vivo and sprouting angiogenesis in vitro (Ellertsdottir et al., 2010). More specifically, it was shown that apical endothelial cell surfaces repulse from each other to give rise to a small vascular lumen and that subsequent VEGF-driven changes in the endothelial F-actin cytoskeleton widen the lumen. In addition, a crosstalk between beta1-integrin and VEGFR2 as well as VEGFR3 signaling has been identified in the developing blood and lymphatic vasculature, respectively.
Previous work
The Lammert group has sufficient experience in genetically, biochemically and light microscopically investigating cardiovascular development and growth in the developing mouse and in sprouting blood vessels. More specifically, the Lammert lab has been working on the role of VEGF-A and VE-cadherin as well as beta1-integrin, VEGFR2 and VEGFR3 signaling in blood and lymphatic vessel formation in developing mouse embryos.
In turn, the Peirce lab has extensive experience in investigating arterialization and arterial adaptation processes in adult mice during ischemia and other pathologic processes. In addition, the Peirce lab has been using mathematical and computational models to study angiogenesis and arteriogenesis, such as Agent Based Modeling (ABM), which is suitable to model both sprouting angiogenesis and arterial adaptation in adult mice. Whereas the Lammert laboratory focuses on basic mechanisms of sprouting angiogenesis and embryonic aorta formation, thus facilitating the generation of simple models for lumen formation in arteries and sprouts, the Peirce laboratory focuses on more complicated, but medically relevant pathomechanisms that induce neovascularization following tissue ischemia. The labs use complementary assays for studying sprouting angiogenesis and vascular growth. Moreover, both laboratories extensively stain vascular networks using immunohistochemistry and image blood vessels using laser-scanning microscopy (LSM). Finally, both laboratories analyze blood vessel morphologies using quantitative image analysis programs.
Aims
The working hypothesis of the project is that crosstalk between integrin and VEGFR2 signaling influence sprouting angiogenesis and vascular growth. This combined activity enhances vascular sprouting and vessel growth, both under embryonic, physiologic (Lammert) and adult, pathologic (Peirce) conditions. As a basis for the collaborative project, an ABM of sprouting angiogenesis and arterial adaptation to hypertension is used. This model simulates sprouting angiogenesis as well as arterial growth during homeostasis and in response to both transient and sustained increases in blood pressure. Importantly, the model will be used to make predictions for experiments on the developing and adult arteries, such as mouse aorta. These predictions can be easily tested using whole embryo culture (WEC) of mouse embryos injected with substances that interfere with beta1-integrin and VEGFR2 signaling. In addition, the blood pressure can be changed in developing mouse embryos. Once the results of these experiments have been entered into the ABM-based model, selected signals (both biochemical and mechanical cues) will subsequently be tested in the adult mouse aorta under hypertension. Thus, the collaboration between the Peirce and Lammert laboratories enables to compare the physiologic growth of the developing mouse aorta and embryonic vessels with the growth and adaptation of adult arteries during pathologic processes.
Cooperation
Finally, the collaborative project is well embedded in the IRTG, since the agent-based modeling approach can incorporate the experimental findings of the signaling pathways investigated by the other research groups. Moreover, the experimental setups allow testing other signals and incorporating them into the model.