The roles and activation of endocardial Notch signaling in heart regeneration

AbstractAs a highly conserved signaling pathway in metazoans, the Notch pathway plays important roles in embryonic development and tissue regeneration. Recently, cardiac injury and regeneration have become an increasingly popular topic for biomedical research, and Notch signaling has been shown to exert crucial functions during heart regeneration as well. In this review, we briefly summarize the molecular functions of the endocardial Notch pathway in several cardiac injury and stress models. Although there is an increase in appreciating the importance of endocardial Notch signaling in heart regeneration, the mechanism of its activation is not fully understood. This review highlights recent findings on the activation of the endocardial Notch pathway by hemodynamic blood flow change in larval zebrafish ventricle after partial ablation, a process involving primary cilia, mechanosensitive ion channel Trpv4 and mechanosensitive transcription factor Klf2.

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Decoding an organ regeneration switch by dissecting cardiac regeneration enhancers

Development ◽

10.1242/dev.194019 ◽

2020 ◽

Vol 147 (24) ◽

pp. dev194019

Author(s):

Ian J. Begeman ◽

Kwangdeok Shin ◽

Daniel Osorio-Méndez ◽

Andrew Kurth ◽

Nutishia Lee ◽

...

Keyword(s):

Gene Expression ◽

Tissue Regeneration ◽

Cardiac Injury ◽

Transcriptional Response ◽

Cardiac Regeneration ◽

Regulatory Elements ◽

Heart Regeneration ◽

New Paradigm ◽

Closely Related Species ◽

Organ Regeneration

ABSTRACTHeart regeneration in regeneration-competent organisms can be accomplished through the remodeling of gene expression in response to cardiac injury. This dynamic transcriptional response relies on the activities of tissue regeneration enhancer elements (TREEs); however, the mechanisms underlying TREEs are poorly understood. We dissected a cardiac regeneration enhancer in zebrafish to elucidate the mechanisms governing spatiotemporal gene expression during heart regeneration. Cardiac lepb regeneration enhancer (cLEN) exhibits dynamic, regeneration-dependent activity in the heart. We found that multiple injury-activated regulatory elements are distributed throughout the enhancer region. This analysis also revealed that cardiac regeneration enhancers are not only activated by injury, but surprisingly, they are also actively repressed in the absence of injury. Our data identified a short (22 bp) DNA element containing a key repressive element. Comparative analysis across Danio species indicated that the repressive element is conserved in closely related species. The repression mechanism is not operational during embryogenesis and emerges when the heart begins to mature. Incorporating both activation and repression components into the mechanism of tissue regeneration constitutes a new paradigm that might be extrapolated to other regeneration scenarios.

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Myocardial NF-κB activation is essential for zebrafish heart regeneration

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1511209112 ◽

2015 ◽

Vol 112 (43) ◽

pp. 13255-13260 ◽

Cited By ~ 54

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.

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Environmental and Molecular Modulation of Motor Individuality in Larval Zebrafish

Frontiers in Behavioral Neuroscience ◽

10.3389/fnbeh.2021.777778 ◽

2021 ◽

Vol 15 ◽

Author(s):

John Hageter ◽

Matthew Waalkes ◽

Jacob Starkey ◽

Haylee Copeland ◽

Heather Price ◽

...

Keyword(s):

Environmental Factors ◽

Notch Signaling ◽

Individual Variation ◽

Environmental Enrichment ◽

Notch Pathway ◽

Dependent Manner ◽

Behavioral Variation ◽

Directional Bias ◽

Larval Zebrafish ◽

Genetic And Environmental Factors

Innate behavioral biases such as human handedness are a ubiquitous form of inter-individual variation that are not strictly hardwired into the genome and are influenced by diverse internal and external cues. Yet, genetic and environmental factors modulating behavioral variation remain poorly understood, especially in vertebrates. To identify genetic and environmental factors that influence behavioral variation, we take advantage of larval zebrafish light-search behavior. During light-search, individuals preferentially turn in leftward or rightward loops, in which directional bias is sustained and non-heritable. Our previous work has shown that bias is maintained by a habenula-rostral PT circuit and genes associated with Notch signaling. Here we use a medium-throughput recording strategy and unbiased analysis to show that significant individual to individual variation exists in wildtype larval zebrafish turning preference. We classify stable left, right, and unbiased turning types, with most individuals exhibiting a directional preference. We show unbiased behavior is not due to a loss of photo-responsiveness but reduced persistence in same-direction turning. Raising larvae at elevated temperature selectively reduces the leftward turning type and impacts rostral PT neurons, specifically. Exposure to conspecifics, variable salinity, environmental enrichment, and physical disturbance does not significantly impact inter-individual turning bias. Pharmacological manipulation of Notch signaling disrupts habenula development and turn bias individuality in a dose dependent manner, establishing a direct role of Notch signaling. Last, a mutant allele of a known Notch pathway affecter gene, gsx2, disrupts turn bias individuality, implicating that brain regions independent of the previously established habenula-rostral PT likely contribute to inter-individual variation. These results establish that larval zebrafish is a powerful vertebrate model for inter-individual variation with established neural targets showing sensitivity to specific environmental and gene signaling disruptions. Our results provide new insight into how variation is generated in the vertebrate nervous system.

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Notch Signaling Regulation in HCC: From Hepatitis Virus to Non-Coding RNAs

Cells ◽

10.3390/cells10030521 ◽

2021 ◽

Vol 10 (3) ◽

pp. 521

Author(s):

Catia Giovannini ◽

Francesca Fornari ◽

Fabio Piscaglia ◽

Laura Gramantieri

Keyword(s):

Notch Signaling ◽

Cell Fate ◽

Hepatitis Virus ◽

Notch Pathway ◽

Notch Receptor ◽

Gamma Secretase ◽

Stem Cell Maintenance ◽

Pathway Activation ◽

Promising Therapeutic Approach ◽

Conserved Genes

The Notch family includes evolutionary conserved genes that encode for single-pass transmembrane receptors involved in stem cell maintenance, development and cell fate determination of many cell lineages. Upon activation by different ligands, and depending on the cell type, Notch signaling plays pleomorphic roles in hepatocellular carcinoma (HCC) affecting neoplastic growth, invasion capability and stem like properties. A specific knowledge of the deregulated expression of each Notch receptor and ligand, coupled with resultant phenotypic changes, is still lacking in HCC. Therefore, while interfering with Notch signaling might represent a promising therapeutic approach, the complexity of Notch/ligands interactions and the variable consequences of their modulations raises concerns when performed in undefined molecular background. The gamma-secretase inhibitors (GSIs), representing the most utilized approach for Notch inhibition in clinical trials, are characterized by important adverse effects due to the non-specific nature of GSIs themselves and to the lack of molecular criteria guiding patient selection. In this review, we briefly summarize the mechanisms involved in Notch pathway activation in HCC supporting the development of alternatives to the γ-secretase pan-inhibitor for HCC therapy.

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Notch restricts lymphatic vessel sprouting induced by vascular endothelial growth factor

Blood ◽

10.1182/blood-2010-11-317800 ◽

2011 ◽

Vol 118 (4) ◽

pp. 1154-1162 ◽

Cited By ~ 73

Author(s):

Wei Zheng ◽

Tuomas Tammela ◽

Masahiro Yamamoto ◽

Andrey Anisimov ◽

Tanja Holopainen ◽

...

Keyword(s):

Notch Signaling ◽

Cell Fate ◽

Target Genes ◽

Notch Pathway ◽

Lymphatic Vessels ◽

Soluble Form ◽

Fibrin Gel ◽

3 Dimensional ◽

Endothelial Growth Factor

Abstract Notch signaling plays a central role in cell-fate determination, and its role in lateral inhibition in angiogenic sprouting is well established. However, the role of Notch signaling in lymphangiogenesis, the growth of lymphatic vessels, is poorly understood. Here we demonstrate Notch pathway activity in lymphatic endothelial cells (LECs), as well as induction of delta-like ligand 4 (Dll4) and Notch target genes on stimulation with VEGF or VEGF-C. Suppression of Notch signaling by a soluble form of Dll4 (Dll4-Fc) synergized with VEGF in inducing LEC sprouting in 3-dimensional (3D) fibrin gel assays. Expression of Dll4-Fc in adult mouse ears promoted lymphangiogenesis, which was augmented by coexpressing VEGF. Lymphangiogenesis triggered by Notch inhibition was suppressed by a monoclonal VEGFR-2 Ab as well as soluble VEGF and VEGF-C/VEGF-D ligand traps. LECs transduced with Dll4 preferentially adopted the tip cell position over nontransduced cells in 3D sprouting assays, suggesting an analogous role for Dll4/Notch in lymphatic and blood vessel sprouting. These results indicate that the Notch pathway controls lymphatic endothelial quiescence, and explain why LECs are poorly responsive to VEGF compared with VEGF-C. Understanding the role of the Notch pathway in lymphangiogenesis provides further insight for the therapeutic manipulation of the lymphatic vessels.

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Notch Signaling Is Involved in Expression of Thyrocyte Differentiation Markers and Is Down-Regulated in Thyroid Tumors

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2008-0528 ◽

2008 ◽

Vol 93 (10) ◽

pp. 4080-4087 ◽

Cited By ~ 44

Author(s):

E. Ferretti ◽

E. Tosi ◽

A. Po ◽

A. Scipioni ◽

R. Morisi ◽

...

Keyword(s):

Gene Expression ◽

Thyroid Cancer ◽

Notch Signaling ◽

Notch Pathway ◽

Human Thyroid ◽

Thyroid Tumors ◽

Follicular Cells ◽

Differentiation Markers ◽

Thyroid Follicular Cells ◽

Thyroid Cancer Cells

Context: Notch genes encode receptors for a signaling pathway that regulates cell growth and differentiation in various contexts, but the role of Notch signaling in thyroid follicular cells has never been fully published. Objective: The objective of the study was to characterize the expression of Notch pathway components in thyroid follicular cells and Notch signaling activities in normal and transformed thyrocytes. Design/Setting and Patients: Expression of Notch pathway components and key markers of thyrocyte differentiation was analyzed in murine and human thyroid tissues (normal and tumoral) by quantitative RT-PCR and immunohistochemistry. The effects of Notch overexpression in human thyroid cancer cells and FTRL-5 cells were explored with analysis of gene expression, proliferation assays, and experiments involving transfection of a luciferase reporter construct containing human NIS promoter regions. Results: Notch receptors are expressed during the development of murine thyrocytes, and their expression levels parallel those of thyroid differentiation markers. Notch signaling characterized also normal adult thyrocytes and is regulated by TSH. Notch pathway components are variably expressed in human normal thyroid tissue and thyroid tumors, but expression levels are clearly reduced in undifferentiated tumors. Overexpression of Notch-1 in thyroid cancer cells restores differentiation, reduces cell growth rates, and stimulates NIS expression via a direct action on the NIS promoter. Conclusion: Notch signaling is involved in the determination of thyroid cell fate and is a direct regulator of thyroid-specific gene expression. Its deregulation may contribute to the loss of differentiation associated with thyroid tumorigenesis.

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Abstract 3380: Acetylation-dependent Regulation Of Notch1 Signaling In Endothelial Cells

Circulation ◽

10.1161/circ.118.suppl_18.s_415-c ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Virginia Guarani ◽

Franck Dequiedt ◽

Andreas M Zeiher ◽

Stefanie Dimmeler ◽

Michael Potente

Keyword(s):

Endothelial Cells ◽

Notch Signaling ◽

Cell Fate ◽

Molecular Mechanisms ◽

Trichostatin A ◽

Notch Pathway ◽

Dependent Manner ◽

Class Iii ◽

Cell Fate Decisions ◽

Knock Down

The Notch signaling pathway is a versatile regulator of cell fate decisions and plays an essential role for embryonic and postnatal vascular development. As only modest differences in Notch pathway activity suffice to determine dramatic differences in blood vessel development, this pathway is tightly regulated by a variety of molecular mechanisms. Reversible acetylation has emerged as an important post-translational modification of several non-histone proteins, which are targeted by histone deacetylases (HDACs). Here, we report that specifically the Notch1 intracellular domain (NICD) is itself an acetylated protein and that its acetylation level is tightly regulated by the SIRT1 deacetylase, which we have previously identified as a key regulator of endothelial angiogenic functions during vascular growth. Coexpression of NICD with histone acetyltransferases such as p300 or PCAF induced a dose- and time-dependent acetylation of NICD. Blocking HDAC activity using the class III HDAC inhibitor nicotinamid (NAM), but not the class I/II HDAC inhibior trichostatin A, resulted in a significant increase of NICD acetylation suggesting that NICD is targetd by class III HDACs for deacetylation. Among the class III HDACs with deacetylase activity (SIRT1, 2, 3, 5), knock down of specifically SIRT1 resulted in enhanced acetylation of NICD. Moreover, wild type SIRT1, but not a catalytically inactive mutant catalyzed the deacetylation of NICD in a nicotinamid-dependent manner. SIRT1, but SIRT2, SIRT3 or SIRT5, associated with NICD through its catalytic domain demonstrating that SIRT1 is a direct NICD deacetylase. Enhancing NICD acetylation by either overexpression of p300 or inhibition of SIRT1 activity using NAM or RNAi-mediated knock down resulted in enhanced NICD protein stability by blocking its ubiquitin-mediated degradation. Consistent with these results, loss of SIRT1 amplified Notch target gene expression in endothelial cells in response to NICD overexpression or treatment with the Notch ligand Dll4. In summary, our results identify reversible acetylation of NICD as a novel molecular mechanism to control Notch signaling and suggest that deacetylation of NICD by SIRT1 plays a key role in the dynamic regulation of Notch signaling in endothelial cells.

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Vertebrate cardiac regeneration: evolutionary and developmental perspectives

Cell Regeneration ◽

10.1186/s13619-020-00068-y ◽

2021 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Stephen Cutie ◽

Guo N. Huang

Keyword(s):

Cardiac Injury ◽

Adaptive Immune System ◽

Cardiac Regeneration ◽

Heart Regeneration ◽

Adaptive Immune ◽

Selective Pressures ◽

Trade Offs ◽

Lower Vertebrates ◽

Complex Adaptive ◽

And Function

AbstractCardiac regeneration is an ancestral trait in vertebrates that is lost both as more recent vertebrate lineages evolved to adapt to new environments and selective pressures, and as members of certain species developmentally progress towards their adult forms. While higher vertebrates like humans and rodents resolve cardiac injury with permanent fibrosis and loss of cardiac output as adults, neonates of these same species can fully regenerate heart structure and function after injury – as can adult lower vertebrates like many teleost fish and urodele amphibians. Recent research has elucidated several broad factors hypothesized to contribute to this loss of cardiac regenerative potential both evolutionarily and developmentally: an oxygen-rich environment, vertebrate thermogenesis, a complex adaptive immune system, and cancer risk trade-offs. In this review, we discuss the evidence for these hypotheses as well as the cellular participators and molecular regulators by which they act to govern heart regeneration in vertebrates.

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ZFP57 dictates allelic expression switch of target imprinted genes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2005377118 ◽

2021 ◽

Vol 118 (5) ◽

pp. e2005377118

Author(s):

Weijun Jiang ◽

Jiajia Shi ◽

Jingjie Zhao ◽

Qiu Wang ◽

Dan Cong ◽

...

Keyword(s):

Dna Methylation ◽

Notch Signaling ◽

Notch Pathway ◽

Notch Signaling Pathway ◽

Mouse Embryos ◽

The Other ◽

Allelic Expression ◽

Monoallelic Expression ◽

Imprinted Genes ◽

Parent Of Origin

ZFP57 is a master regulator of genomic imprinting. It has both maternal and zygotic functions that are partially redundant in maintaining DNA methylation at some imprinting control regions (ICRs). In this study, we found that DNA methylation was lost at most known ICRs in Zfp57 mutant embryos. Furthermore, loss of ZFP57 caused loss of parent-of-origin–dependent monoallelic expression of the target imprinted genes. The allelic expression switch occurred in the ZFP57 target imprinted genes upon loss of differential DNA methylation at the ICRs in Zfp57 mutant embryos. Specifically, upon loss of ZFP57, the alleles of the imprinted genes located on the same chromosome with the originally methylated ICR switched their expression to mimic their counterparts on the other chromosome with unmethylated ICR. Consistent with our previous study, ZFP57 could regulate the NOTCH signaling pathway in mouse embryos by impacting allelic expression of a few regulators in the NOTCH pathway. In addition, the imprinted Dlk1 gene that has been implicated in the NOTCH pathway was significantly down-regulated in Zfp57 mutant embryos. Our allelic expression switch models apply to the examined target imprinted genes controlled by either maternally or paternally methylated ICRs. Our results support the view that ZFP57 controls imprinted expression of its target imprinted genes primarily through maintaining differential DNA methylation at the ICRs.

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Serrate and Notch specify cell fates in the heart field by suppressing cardiomyogenesis

Development ◽

10.1242/dev.127.17.3865 ◽

2000 ◽

Vol 127 (17) ◽

pp. 3865-3876

Author(s):

M.S. Rones ◽

K.A. McLaughlin ◽

M. Raffin ◽

M. Mercola

Keyword(s):

Gene Expression ◽

Notch Signaling ◽

Cell Fate ◽

Notch Pathway ◽

Cell Types ◽

Myocardial Cell ◽

Dominant Negative ◽

Cell Fates ◽

Cell Fate Decisions ◽

Heart Field

Notch signaling mediates numerous developmental cell fate decisions in organisms ranging from flies to humans, resulting in the generation of multiple cell types from equipotential precursors. In this paper, we present evidence that activation of Notch by its ligand Serrate apportions myogenic and non-myogenic cell fates within the early Xenopus heart field. The crescent-shaped field of heart mesoderm is specified initially as cardiomyogenic. While the ventral region of the field forms the myocardial tube, the dorsolateral portions lose myogenic potency and form the dorsal mesocardium and pericardial roof (Raffin, M., Leong, L. M., Rones, M. S., Sparrow, D., Mohun, T. and Mercola, M. (2000) Dev. Biol., 218, 326–340). The local interactions that establish or maintain the distinct myocardial and non-myocardial domains have never been described. Here we show that Xenopus Notch1 (Xotch) and Serrate1 are expressed in overlapping patterns in the early heart field. Conditional activation or inhibition of the Notch pathway with inducible dominant negative or active forms of the RBP-J/Suppressor of Hairless [Su(H)] transcription factor indicated that activation of Notch feeds back on Serrate1 gene expression to localize transcripts more dorsolaterally than those of Notch1, with overlap in the region of the developing mesocardium. Moreover, Notch pathway activation decreased myocardial gene expression and increased expression of a marker of the mesocardium and pericardial roof, whereas inhibition of Notch signaling had the opposite effect. Activation or inhibition of Notch also regulated contribution of individual cells to the myocardium. Importantly, expression of Nkx2. 5 and Gata4 remained largely unaffected, indicating that Notch signaling functions downstream of heart field specification. We conclude that Notch signaling through Su(H) suppresses cardiomyogenesis and that this activity is essential for the correct specification of myocardial and non-myocardial cell fates.

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