Xenbase Image ID: 153876

Fig. 6. Model depicting role of Lhx9 in epicardial development in Xenopus. (A) During early tadpole stages, the epicardial lineage is determined and marked by transcription factors tcf21, tbx18, wt1 and lhx9 (blue) as a bilateral population of cells on the septum transversum caudal to the heart (red). (B) Lhx9 functions to drive clustering of cells to form the proepicardial cluster on the right side of the embryo (blue), whereby itga4 expression is activated. At this stage, signaling factors, most likely BMP (yellow arrows), from the heart atrioventricular sulcus (AVS) direct epicardial migration. (C,D) Lhx9-integrin-mediated signaling, including focal adhesion (FA) formation and phosphorylation of paxillin (pPaxillin), allows the PEO bridge (blue) to attach to the heart (red) at the AVS. (E,F) Once the PEO has attached to the heart, deposition of essential ECM components such as fibronectin and laminin are required for the epicardial layer (epic) to adhere and spread over the heart surface. Image published in: Tandon P et al. (2016) Copyright © 2016. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Larger Image Printer Friendly View

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