Abstract
The epicardium, the outer layer of the heart, has been of interest in cardiac research due to its vital role in the developing and diseased heart. During development, epicardial cells are active and supply cells and paracrine cues to the myocardium. In the injured adult heart, the epicardium is re-activated and recapitulates embryonic behavior that is essential for a proper repair response. Two indispensable processes for epicardial contribution to heart tissue formation are epithelial to mesenchymal transition (EMT), and tissue invasion. One of the key groups of cytokines regulating both EMT and invasion is the transforming growth factor β (TGFβ) family, including TGFβ and Bone Morphogenetic Protein (BMP). Abundant research has been performed to understand the role of TGFβ family signaling in the developing epicardium. However, less is known about signaling in the adult epicardium. This review provides an overview of the current knowledge on the role of TGFβ in epicardial behavior both in the development and in the repair of the heart. We aim to describe the presence of involved ligands and receptors to establish if and when signaling can occur. Finally, we discuss potential targets to improve the epicardial contribution to cardiac repair as a starting point for future investigation.
Highlights
The Epicardial TimelineThe epicardium, a mesothelial layer covering the heart, has been recognized as a distinct structure for a long time, whilst its origin and function remained uncertain
Viral induction of caALK5 in chick heart explant cultures induced epicardial invasion into a collagen gel [60]. This data confirms the in vivo observation that transforming growth factor β (TGFβ) and its signaling is crucial for epicardial behavior, and that ALK5 signaling is involved in the induction of both epicardial epithelial to mesenchymal transition (EMT) and invasion
In this review we aimed to provide a structured overview of the role of multiple ligands and receptors of the TGFβ family in epicardial behavior
Summary
The epicardium, a mesothelial layer covering the heart, has been recognized as a distinct structure for a long time, whilst its origin and function remained uncertain. In the adult heart there appears to be limited migration of epicardial derived cells into the injured myocardium [18,19] This observation created a window of opportunity to boost the epicardial response to improve cardiac regeneration, which has emerged as an area of active research. A signaling pathway that is involved in many processes underlying epicardial behavior is the transforming growth factor (TGF) β pathway This family of growth factors, well known for its role in EMT and invasion of cells of different origins [24], is considered to be important for epicardial cell behavior during development and is a potential target for rejuvenating the adult epicardium. We will discuss potential targets to improve the epicardial contribution to cardiac repair as a starting point for future investigation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
