Departments of Surgery and Pathology, Keck School of Medicine, University of Southern California, and The Saban Research Institute, Childrens Hospital Los Angeles, Los Angeles, CA 90027, USA.
Proc Natl Acad Sci U S A. 2010 Oct 5;107(40):17206-10. doi: 10.1073/pnas.0915016107. Epub 2010 Sep 21.
A zebrafish heart can fully regenerate after amputation of up to 20% of its ventricle. During this process, newly formed coronary blood vessels revascularize the regenerating tissue. The formation of coronary blood vessels during zebrafish heart regeneration likely recapitulates embryonic coronary vessel development, which involves the activation and proliferation of the epicardium, followed by an epithelial-to-mesenchymal transition. The molecular and cellular mechanisms underlying these processes are not well understood. We examined the role of PDGF signaling in explant-derived primary cultured epicardial cells in vitro and in regenerating zebrafish hearts in vivo. We observed that mural and mesenchymal cell markers, including pdgfrβ, are up-regulated in the regenerating hearts. Using a primary culture of epicardial cells derived from heart explants, we found that PDGF signaling is essential for epicardial cell proliferation. PDGF also induces stress fibers and loss of cell-cell contacts of epicardial cells in explant culture. This effect is mediated by Rho-associated protein kinase. Inhibition of PDGF signaling in vivo impairs epicardial cell proliferation, expression of mesenchymal and mural cell markers, and coronary blood vessel formation. Our data suggest that PDGF signaling plays important roles in epicardial function and coronary vessel formation during heart regeneration in zebrafish.
斑马鱼的心脏在切除 20%的心室后可以完全再生。在这个过程中，新形成的冠状血管使再生组织重新得到血液供应。斑马鱼心脏再生过程中冠状血管的形成可能再现了胚胎冠状血管的发育，涉及心外膜的激活和增殖，随后是上皮细胞向间充质细胞的转变。这些过程背后的分子和细胞机制尚不清楚。我们研究了 PDGF 信号在体外分离的原代培养心外膜细胞和体内再生的斑马鱼心脏中的作用。我们观察到，在再生的心脏中，壁细胞和间充质细胞标志物，包括 pdgfrβ，上调。通过从心脏外植体分离的原代培养心外膜细胞，我们发现 PDGF 信号对于心外膜细胞的增殖是必需的。PDGF 还诱导外植体培养中的心外膜细胞中的应激纤维和细胞-细胞接触的丧失。这种作用是由 Rho 相关蛋白激酶介导的。体内 PDGF 信号的抑制会损害心外膜细胞的增殖、间充质和壁细胞标志物的表达以及冠状血管的形成。我们的数据表明，PDGF 信号在斑马鱼心脏再生过程中心外膜功能和冠状血管形成中发挥重要作用。
