How new blood vessels sprout
IBS biologists discovered a key regulator of normal as well as pathological formation of new blood vessels
New blood vessels branch out of preexisting ones is via a process called angiogenesis. Although this is essential for survival, development and wound healing, on the flip side, it also feeds and progresses malignant tumors, as well as other diseases. IBS scientists at the Center for Vascular Research, within the Institute for Basic Science (IBS), in collaboration with LIM Dae-Sik at KAIST, discovered a key regulator of this process, which could become a potential therapeutic target for treating diseases associated with the formation of new blood vessels.
Cells forming the wall of blood vessels, endothelial cells (ECs), are the main actors of angiogenesis. The formation of a new vascular wall is a multistep process that requires coordinated cell migration, proliferation, and junction formation. ECs need to stretch and move and to do that, they use their own “skeleton”, the cytoskeleton. The ECs at the front of the migration route are called tip cells and the ones at the base the stalk cells. Tip cells form extensions that help them to creep into the connective tissue. Then, as the new vessel grows out of the existing one, cells also need to create strong bonds to assure a robust wall. Each step is controlled by several proteins whose behavior is only beginning to be understood.
The research team found out that in the presence of growth stimuli, the proteins YAP and TAZ are critical for sprouting angiogenesis, vascular barrier formation, and maturation. YAP and TAZ work together and they have been re-dubbed YAP/TAZ. YAP/TAZ is negatively controlled by the Hippo signaling pathway, a “molecular conversation” whose role is to adjust the organ size to a normal volume. Curiously, mutations in the proteins of this pathway cause oversized organs, from that the name “hippo”….