scholarly journals Prrx1b restricts fibrosis and promotes Nrg1-dependent cardiomyocyte proliferation during zebrafish heart regeneration

Development ◽  
2021 ◽  
Author(s):  
Dennis E.M. de Bakker ◽  
Mara Bouwman ◽  
Esther Dronkers ◽  
Filipa C. Simões ◽  
Paul R. Riley ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cardiac Injury ◽  
Lineage Tracing ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Fibrotic Scar ◽  
Ligand Expression ◽  
Zebrafish Heart

Fibroblasts are activated to repair the heart following injury. Fibroblast activation in the mammalian heart leads to a permanent fibrotic scar that impairs cardiac function. In other organisms, like zebrafish, cardiac injury is followed by transient fibrosis and scar-free regeneration. The mechanisms that drive scarring versus scar-free regeneration are not well understood. Here we show that the homeo-box containing transcription factor Prrx1b is required for scar-free regeneration of the zebrafish heart as the loss of Prrx1b results in excessive fibrosis and impaired cardiomyocyte proliferation. Through lineage tracing and single-cell RNA-sequencing we find that Prrx1b is activated in epicardial-derived cells (EPDCs) where it restricts TGF-β ligand expression and collagen production. Furthermore, through combined in vitro experiments in human fetal EPDCs and in vivo rescue experiments in zebrafish, we conclude that Prrx1 stimulates Nrg1 expression and promotes cardiomyocyte proliferation. Collectively, these results indicate that Prrx1 is a key transcription factor that balances fibrosis and regeneration in the injured zebrafish heart.

scholarly journals Nrg1 is an injury-induced cardiomyocyte mitogen for the endogenous heart regeneration program in zebrafish

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Matthew Gemberling ◽  
Ravi Karra ◽  
Amy L Dickson ◽  
Kenneth D Poss
Keyword(s):  
Cardiac Injury ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Adult Zebrafish ◽  
Perivascular Cells ◽  
Adult Heart ◽  
Muscle Hyperplasia ◽  
Zebrafish Heart

Heart regeneration is limited in adult mammals but occurs naturally in adult zebrafish through the activation of cardiomyocyte division. Several components of the cardiac injury microenvironment have been identified, yet no factor on its own is known to stimulate overt myocardial hyperplasia in a mature, uninjured animal. In this study, we find evidence that Neuregulin1 (Nrg1), previously shown to have mitogenic effects on mammalian cardiomyocytes, is sharply induced in perivascular cells after injury to the adult zebrafish heart. Inhibition of Erbb2, an Nrg1 co-receptor, disrupts cardiomyocyte proliferation in response to injury, whereas myocardial Nrg1 overexpression enhances this proliferation. In uninjured zebrafish, the reactivation of Nrg1 expression induces cardiomyocyte dedifferentiation, overt muscle hyperplasia, epicardial activation, increased vascularization, and causes cardiomegaly through persistent addition of wall myocardium. Our findings identify Nrg1 as a potent, induced mitogen for the endogenous adult heart regeneration program.

scholarly journals Myocardial NF-κB activation is essential for zebrafish heart regeneration

2015 ◽  
Vol 112 (43) ◽  
pp. 13255-13260 ◽  
Author(s):  
Ravi Karra ◽  
Anne K. Knecht ◽  
Kazu Kikuchi ◽  
Kenneth D. Poss
Keyword(s):  
Tissue Regeneration ◽  
Therapeutic Strategy ◽  
Cardiac Injury ◽  
Regulatory Sequences ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Developmental Program ◽  
Lower Vertebrates ◽  
Outstanding Question ◽  
Zebrafish Heart

Heart regeneration offers a novel therapeutic strategy for heart failure. Unlike mammals, lower vertebrates such as zebrafish mount a strong regenerative response following cardiac injury. Heart regeneration in zebrafish occurs by cardiomyocyte proliferation and reactivation of a cardiac developmental program, as evidenced by induction of gata4 regulatory sequences in regenerating cardiomyocytes. Although many of the cellular determinants of heart regeneration have been elucidated, how injury triggers a regenerative program through dedifferentiation and epicardial activation is a critical outstanding question. Here, we show that NF-κB signaling is induced in cardiomyocytes following injury. Myocardial inhibition of NF-κB activity blocks heart regeneration with pleiotropic effects, decreasing both cardiomyocyte proliferation and epicardial responses. Activation of gata4 regulatory sequences is also prevented by NF-κB signaling antagonism, suggesting an underlying defect in cardiomyocyte dedifferentiation. Our results implicate NF-κB signaling as a key node between cardiac injury and tissue regeneration.

scholarly journals Transcription factor Tlx1 marks a subset of lymphoid tissue organizer-like mesenchymal progenitor cells in the neonatal spleen

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuta Ueno ◽  
Keiko Fujisaki ◽  
Shoko Hosoda ◽  
Yusuke Amemiya ◽  
Shogo Okazaki ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Progenitor Cells ◽  
Stromal Cells ◽  
Lymphoid Tissue ◽  
Stromal Cell ◽  
Lineage Tracing ◽  
Mesenchymal Progenitor Cells ◽  
Reticular Cells

AbstractThe spleen is comprised of spatially distinct compartments whose functions, such as immune responses and removal of aged red blood cells, are tightly controlled by the non-hematopoietic stromal cells that provide regionally-restricted signals to properly activate hematopoietic cells residing in each area. However, information regarding the ontogeny and relationships of the different stromal cell types remains limited. Here we have used in vivo lineage tracing analysis and in vitro mesenchymal stromal cell assays and found that Tlx1, a transcription factor essential for embryonic spleen organogenesis, marks neonatal stromal cells that are selectively localized in the spleen and retain mesenchymal progenitor potential to differentiate into mature follicular dendritic cells, fibroblastic reticular cells and marginal reticular cells. Furthermore, by establishing a novel three-dimensional cell culture system that enables maintenance of Tlx1-expressing cells in vitro, we discovered that signals from the lymphotoxin β receptor and TNF receptor promote differentiation of these cells to express MAdCAM-1, CCL19 and CXCL13, representative functional molecules expressed by different subsets of mature stromal cells in the spleen. Taken together, these findings indicate that mesenchymal progenitor cells expressing Tlx1 are a subset of lymphoid tissue organizer-like cells selectively found in the neonatal spleen.

scholarly journals Induction of Wnt signaling antagonists and P21-activated kinase enhances cardiomyocyte proliferation during zebrafish heart regeneration

2020 ◽  
Author(s):  
Xiangwen Peng ◽  
Kaa Seng Lai ◽  
Peilu She ◽  
Junsu Kang ◽  
Tingting Wang ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Cardiac Tissue ◽  
Cardiac Injury ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Cardiac Damage ◽  
Ectopic Activation ◽  
P21 Activated Kinase ◽  
Wnt Inhibitors ◽  
Zebrafish Heart

Abstract Heart regeneration occurs by dedifferentiation and proliferation of pre-existing cardiomyocytes (CMs). However, the signaling mechanisms by which injury induces CM renewal remain incompletely understood. Here, we find that cardiac injury in zebrafish induces expression of the secreted Wnt inhibitors, including Dickkopf 1 (Dkk1), Dkk3, secreted Frizzled-related protein 1 (sFrp1), and sFrp2, in cardiac tissue adjacent to injury sites. Experimental blocking of Wnt activity via Dkk1 overexpression enhances CM proliferation and heart regeneration, whereas ectopic activation of Wnt8 signaling blunts injury-induced CM dedifferentiation and proliferation. Although Wnt signaling is dampened upon injury, the cytoplasmic β-catenin is unexpectedly increased at disarrayed CM sarcomeres in myocardial wound edges. Our analyses indicated that P21-activated kinase 2 (Pak2) is induced at regenerating CMs, where it phosphorylates cytoplasmic β-catenin at Ser675 and increases its stability at disassembled sarcomeres during regeneration. Myocardial-specific induction of the phospho-mimetic β-catenin (S675E) enhances CM dedifferentiation and sarcomere disassembly in response to cardiac damage. Importantly, inactivation of Pak2 kinase activity reduces the Ser675-phosphorylated β-catenin (pS675-β-catenin) at cardiac wounds and attenuates CM sarcomere disorganization, dedifferentiation, and proliferation. Taken together, these findings demonstrate that coordination of Wnt signaling inhibition and Pak2/pS675-β-catenin signaling enhances zebrafish heart regeneration by supporting CM dedifferentiation and proliferation.

scholarly journals Fosl1 is vital to heart regeneration upon apex resection in adult Xenopus tropicalis

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Hai-Yan Wu ◽  
Yi-Min Zhou ◽  
Zhu-Qin Liao ◽  
Jia-Wen Zhong ◽  
You-Bin Liu ◽  
...  
Keyword(s):  
Early Stage ◽  
Dominant Negative ◽  
Luciferase Reporter ◽  
Heart Regeneration ◽  
Cell Cycle Regulators ◽  
Cardiomyocyte Proliferation ◽  
Neonatal Mice ◽  
Heart Injury

AbstractCardiovascular disease is the leading cause of death in the world due to losing regenerative capacity in the adult heart. Frogs possess remarkable capacities to regenerate multiple organs, including spinal cord, tail, and limb, but the response to heart injury and the underlying molecular mechanism remains largely unclear. Here we demonstrated that cardiomyocyte proliferation greatly contributes to heart regeneration in adult X. tropicalis upon apex resection. Using RNA-seq and qPCR, we found that the expression of Fos-like antigen 1 (Fosl1) was dramatically upregulated in early stage of heart injury. To study Fosl1 function in heart regeneration, its expression was modulated in vitro and in vivo. Overexpression of X. tropicalis Fosl1 significantly promoted the proliferation of cardiomyocyte cell line H9c2. Consistently, endogenous Fosl1 knockdown suppressed the proliferation of H9c2 cells and primary cardiomyocytes isolated from neonatal mice. Taking use of a cardiomyocyte-specific dominant-negative approach, we show that blocking Fosl1 function leads to defects in cardiomyocyte proliferation during X. tropicalis heart regeneration. We further show that knockdown of Fosl1 can suppress the capacity of heart regeneration in neonatal mice, but overexpression of Fosl1 can improve the cardiac function in adult mouse upon myocardium infarction. Co-immunoprecipitation, luciferase reporter, and ChIP analysis reveal that Fosl1 interacts with JunB and promotes the expression of Cyclin-T1 (Ccnt1) during heart regeneration. In conclusion, we demonstrated that Fosl1 plays an essential role in cardiomyocyte proliferation and heart regeneration in vertebrates, at least in part, through interaction with JunB, thereby promoting expression of cell cycle regulators including Ccnt1.

scholarly journals Midkine-a regulates the formation of a fibrotic scar during zebrafish heart regeneration

2021 ◽  
Author(s):  
Dimitrios Grivas ◽  
Álvaro González-Rajal ◽  
José Luis de la Pompa
Keyword(s):  
Critical Role ◽  
Cardiac Injury ◽  
Transcriptional Analysis ◽  
Endothelial Cell Proliferation ◽  
Heart Regeneration ◽  
Knock Out ◽  
Tgfβ Signalling ◽  
Fibrotic Scar ◽  
Zebrafish Heart

AbstractThe adult zebrafish heart regenerates after injury, unlike the hearts of mammals. Heart cryoinjury triggers the formation of a fibrotic scar that gradually degrades, leading to regeneration. Midkine-a (Mdka) is a multifunctional cytokine that is activated after cardiac injury. Here, we investigated the role of mdka in zebrafish heart regeneration. We show that mdka expression is strongly induced at 1-day post cryoinjury (dpci) throughout the epicardium, whereas by 7 dpci expression has become restricted to epicardial cells covering the injured area. To study the role of mdka in heart regeneration, we generated mdka-knock out (KO) zebrafish strains. Analysis of injured hearts showed that loss of mdka decreased endothelial cell proliferation and resulted in a blockade of heart regeneration characterized by retention of a collagenous scar. Transcriptional analysis revealed increases in collagen transcription and TGFβ signalling activity. These results reveal a critical role for mdka in fibrosis regulation during heart regeneration.

scholarly journals Midkine-a Regulates the Formation of a Fibrotic Scar During Zebrafish Heart Regeneration

2021 ◽  
Vol 9 ◽  
Author(s):  
Dimitrios Grivas ◽  
Álvaro González-Rajal ◽  
José Luis de la Pompa
Keyword(s):  
Critical Role ◽  
Cardiac Injury ◽  
Transcriptional Analysis ◽  
Endothelial Cell Proliferation ◽  
Heart Regeneration ◽  
Knock Out ◽  
Injured Area ◽  
Fibrotic Scar ◽  
Zebrafish Heart

Unlike the hearts of mammals, the adult zebrafish heart regenerates after injury. Heart cryoinjury in zebrafish triggers the formation of a fibrotic scar that gradually degrades, leading to regeneration. Midkine-a (Mdka) is a multifunctional cytokine that is activated after cardiac injury. Here, we investigated the role of mdka in zebrafish heart regeneration. We show that mdka expression was induced at 1-day post-cryoinjury (dpci) throughout the epicardial layer, whereas by 7 dpci expression had become restricted to the epicardial cells covering the injured area. To study the role of mdka in heart regeneration, we generated mdka-knock out (KO) zebrafish strains. Analysis of injured hearts showed that loss of mdka decreased endothelial cell proliferation and resulted in an arrest in heart regeneration characterized by retention of a collagenous scar. Transcriptional analysis revealed increases in collagen transcription and intense TGFβ signaling activity. These results reveal a critical role for mdka in fibrosis regulation during heart regeneration.

scholarly journals Ephrin-B1 blocks adult cardiomyocyte proliferation and heart regeneration

2019 ◽  
Author(s):  
Marie Cauquil ◽  
Céline Mias ◽  
Céline Guilbeau-Frugier ◽  
Clément Karsenty ◽  
Marie-Hélène Seguelas ◽  
...  
Keyword(s):  
Resting State ◽  
Cardiac Tissue ◽  
Hippo Pathway ◽  
Cardiac Regeneration ◽  
Mouse Heart ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Postnatal Maturation

AbstractAimsDeciphering the innate mechanisms governing the blockade of proliferation in adult cardiomyocytes (CMs) is challenging for mammalian heart regeneration. Despite the exit of CMs from the cell cycle during the postnatal maturation period coincides with their morphological switch to a typical adult rod-shape, whether these two processes are connected is unknown. Here, we examined the role of ephrin-B1, a CM rod-shape stabilizer, in adult CM proliferation and cardiac regeneration.Methods and resultsTransgenic- or AAV9-based ephrin-B1 repression in adult mouse heart led to substantial proliferation of resident CMs and tissue regeneration to compensate for apex resection, myocardial infarction (MI) and senescence. Interestingly, in the resting state, CMs lacking ephrin-B1 did not constitutively proliferate, indicative of no major cardiac defects. However, they exhibited proliferation-competent signature, as indicated by higher mononucleated state and a dramatic decrease of miR-195 mitotic blocker, which can be mobilized under neuregulin-1 stimulation in vitro and in vivo. Mechanistically, the post-mitotic state of the adult CM relies on ephrin-B1 sequestering of inactive phospho-Yap1, the effector of the Hippo-pathway, at the lateral membrane. Hence, ephrin-B1 repression leads to phospho-Yap1 release in the cytosol but CM quiescence at resting state. Upon cardiac stresses (apectomy, MI, senescence), Yap1 could be activated and translocated to the nucleus to induce proliferation-gene expression and consequent CM proliferationConclusionsOur results identified ephrin-B1 as a new natural locker of adult CM proliferation and emphasize that targeting ephrin-B1 may prove a future promising approach in cardiac regenerative medicine for HF treatment.SignificanceThe mammalian adult heart is unable to regenerate due to the inability of cardiomyocytes (CMs) to proliferate and replace cardiac tissue lost. Exploiting CM-specific transgenic mice or AAV9-based gene therapy, this works identifies ephrin-B1, a specific rod-shape stabilizer of the adult CM, as a natural padlock of adult CM proliferation for compensatory adaptation to different cardiac stresses (apectomy, MI, senescence), thus emphasizing a new link between the adult CM morphology and their proliferation potential. Moreover, the study demonstrates proof-of-concept that targeting ephrin-B1 may be an innovative therapeutic approach for ischemic heart failure.

scholarly journals Regeneration of the pulmonary vascular endothelium after viral pneumonia requires COUP-TF2

2020 ◽  
Vol 6 (48) ◽  
pp. eabc4493
Author(s):  
Gan Zhao ◽  
Aaron I. Weiner ◽  
Katherine M. Neupauer ◽  
Maria Fernanda de Mello Costa ◽  
Gargi Palashikar ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Vascular Endothelium ◽  
Nuclear Factor Κb ◽  
H1n1 Influenza ◽  
Lineage Tracing ◽  
Neuropilin 1 ◽  
Repair Mechanisms ◽  
And Migration

Acute respiratory distress syndrome is associated with a robust inflammatory response that damages the vascular endothelium, impairing gas exchange. While restoration of microcapillaries is critical to avoid mortality, therapeutic targeting of this process requires a greater understanding of endothelial repair mechanisms. Here, we demonstrate that lung endothelium possesses substantial regenerative capacity and lineage tracing reveals that native endothelium is the source of vascular repair after influenza injury. Ablation of chicken ovalbumin upstream promoter–transcription factor 2 (COUP-TF2) (Nr2f2), a transcription factor implicated in developmental angiogenesis, reduced endothelial proliferation, exacerbating viral lung injury in vivo. In vitro, COUP-TF2 regulates proliferation and migration through activation of cyclin D1 and neuropilin 1. Upon influenza injury, nuclear factor κB suppresses COUP-TF2, but surviving endothelial cells ultimately reestablish vascular homeostasis dependent on restoration of COUP-TF2. Therefore, stabilization of COUP-TF2 may represent a therapeutic strategy to enhance recovery from pathogens, including H1N1 influenza and SARS-CoV-2.

scholarly journals Prrx1b directs pro-regenerative fibroblasts during zebrafish heart regeneration

2020 ◽  
Author(s):  
Dennis E.M. de Bakker ◽  
Esther Dronkers ◽  
Mara Bouwman ◽  
Aryan Vink ◽  
Marie-José Goumans ◽  
...  
Keyword(s):  
Human Heart ◽  
Cardiac Fibrosis ◽  
Lineage Tracing ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Loss Of Function ◽  
Epicardial Cells ◽  
Injured Area ◽  
Novel Therapeutic Strategies ◽  
Zebrafish Heart

ABSTRACTRationaleThe human heart loses millions of cardiomyocytes after an ischemic injury, but is unable to regenerate the lost tissue. Instead, the injured human heart is repaired by pro-fibrotic fibroblasts that form a large permanent scar. In contrast, the injured zebrafish heart regenerates efficiently without the formation of a permanent scar. While fibroblasts have been shown to be indispensable for zebrafish heart regeneration, very little is known about the mechanisms balancing the fibrotic and regenerative response. A better understanding of these mechanisms could lead to the discovery of novel therapeutic strategies to reduce fibrosis and promote heart regeneration.ObjectiveTo identify novel mechanisms that regulate the balance between cardiac fibrosis and scar-free regeneration.Methods and ResultsUsing a genetic approach, we first show that zebrafish prrx1b loss-of-function mutants display reduced cardiomyocyte proliferation and impaired heart regeneration. Using a lineage tracing approach, we show that Prrx1b is expressed in tcf21+ epicardial-derived cells localizing around and inside the injured area. Next, we used a single cell RNA-sequencing approach on sorted tcf21+ cells isolated from injured prrx1b-/- and wild-type hearts and identified two distinct fibroblast populations. With combined bioinformatic and histological analysis we found that prrx1b-/- hearts contain an excess of pro-fibrotic fibroblasts that produce TGF-β ligands and collagens, while fewer pro-regenerative Nrg1-expressing fibroblasts are formed. Furthermore, by injecting recombinant NRG1 in prrx1b-/- fish we were able to rescue their cardiomyocyte proliferation defect. Finally, using cultured human fetal epicardial cells and siRNA mediated knock-down of PRRX1 we found that PRRX1 is required for NRG1 induction in human epicardial-derived cells.ConclusionsPrrx1b in the injured heart restricts fibrosis and stimulates regeneration by directing epicardial-derived cells towards a pro-regenerative Nrg1-producing fibroblast state.

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