Inhibition of TGF-β/Smad3 Signaling Disrupts Cardiomyocyte Cell Cycle Progression and Epithelial–Mesenchymal Transition-Like Response During Ventricle Regeneration

Abstract

Unlike mammals, zebrafish can regenerate injured hearts even in the adult stage. Cardiac regeneration requires the coordination of cardiomyocyte (CM) proliferation and migration. The TGF-β/Smad3 signaling pathway has been implicated in cardiac regeneration, but the molecular mechanisms by which this pathway regulates CM proliferation and migration have not been fully illustrated. Here, we investigated the function of TGF-β/Smad3 signaling in a zebrafish model of ventricular ablation. Multiple components of this pathway were upregulated/activated after injury. Utilizing a specific inhibitor of Smad3, we detected an increased ratio of unrecovered hearts. Transcriptomic analysis suggested that the TGF-β/Smad3 signaling pathway could affect CM proliferation and migration. Further analysis demonstrated that the CM cell cycle was disrupted and the epithelial–mesenchymal transition (EMT)-like response was impaired, which limited cardiac regeneration. Altogether, our study reveals an important function of TGF-β/Smad3 signaling in CM cell cycle progression and EMT process during zebrafish ventricle regeneration.

Reawakening the Intrinsic Cardiac Regenerative Potential: Molecular Strategies to Boost Dedifferentiation and Proliferation of Endogenous Cardiomyocytes

“…The inhibition of TGFβ receptor 1 (TGFBR1) activity by SB-431542 was reported to reduce the number of proliferating cardiomyocytes in zebrafish embryos (120). Intriguingly, robust activation of TGFβ/SMAD3 signaling has been documented during zebrafish heart regeneration, as evidenced by upregulation of TGF ligands (tgfb1a, tgfb1b, tgfb2, and tgfb3), receptors (alk5a known as Tgfbr1, and alk5b known as Tgfbr1b) and the downstream effector SMAD3 (10,121). Furthermore, inhibition of TGFβ/SMAD3 signaling reduces cardiomyocyte cell cycle activity and abolishes heart regeneration in adult zebrafish upon cardiac injury (10,121).…”

Optogenetic control of YAP can enhance the rate of wound healing

“…(41) YAP has also been shown to be a mediator of TGF-b signalling (42,43) and the pathway has been implicated in cardiomyocyte proliferation and migration. (44,45) We observed that the expression levels of all three genes probed were significantly upregulated in cells containing activated optoYAP as compared to wildtype (WT) H9c2 (Fig. 1C).…”

“…(41) YAP has also been shown to be a mediator of TGF-β signalling(42,43) and the pathway has been implicated in cardiomyocyte proliferation and migration. (44,45)…”

“…Additionally, we looked at TGF-β transcript levels, an inflammation-related growth factor that is frequently involved in the migration and invasion of tumour cells (47). YAP has also been shown to be a mediator of TGF- β signalling (48,49) and the pathway has been implicated in cardiomyocyte proliferation and migration (50,51).…”

Dynamic Involvement of Telocytes in Modulating Multiple Signaling Pathways in Cardiac Cytoarchitecture

“…However, the activation of the TGFb pathway stimulates the fibrotic process and matrix protein production that dominates the later stages of MI resolution [ 145 ]. In zebra fish hearts (well known for heart regeneration capacity), TGFβ was proved to be involved in endogenous cardiac regeneration [ 146 ]. Moreover, it is worth mentioning that zebrafish hearts (like newt hearts) are abundant in TCs, at this level by their long and slender telopodes TCs creating trabecula-like volumes in which they are establishing multiple contacts with CMs [ 8 ].…”