Overexpression of the tinman-related genes XNkx-2.5 and XNkx-2.3 in Xenopus embryos results in myocardial hyperplasia

Drosophila tinman is an NK-class homeobox gene required for formation of the dorsal vessel, the insect equivalent of the vertebrate heart. Vertebrate sequences related to tinman, such as mouse Nkx-2.5, chicken cNkx-2.5, Xenopus XNkx-2.5 and XNkx-2.3 are expressed in cardiac precursors and in tissues involved in induction of cardiac mesoderm. Mice which lack a functional Nkx-2.5 gene die due to cardiac defects. To determine the role of tinman-related sequences in heart development, we have overexpressed both XNkx-2.3 and XNkx-2.5 in Xenopus laevis embryos. The resulting embryos are morphologically normal except that they have enlarged hearts. The enlarged heart phenotype is due to a thickening of the myocardium caused by an increase in the overall number of myocardial cells (hyperplasia). Neither ectopic nor precocious expression of cardiac differentiation markers is detectable in overexpressing embryos. These results suggest that both XNkx-2.3 and XNkx-2.5 are functional homologues of tinman, responsible for maintenance of the heart field.

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Nodal signalling in Xenopus : the role of Xnr5 in left/right asymmetry and heart development

Open Biology ◽

10.1098/rsob.150187 ◽

2016 ◽

Vol 6 (8) ◽

pp. 150187 ◽

Cited By ~ 4

Author(s):

Emmanuel Tadjuidje ◽

Matthew Kofron ◽

Adnan Mir ◽

Christopher Wylie ◽

Janet Heasman ◽

...

Keyword(s):

Heart Development ◽

Cardiac Troponin ◽

Axis Formation ◽

Mrna Levels ◽

Blastula Stage ◽

Signalling Molecules ◽

Tailbud Stage ◽

Heart Field ◽

Left Right Asymmetry

Nodal class TGF-β signalling molecules play essential roles in establishing the vertebrate body plan. In all vertebrates, nodal family members have specific waves of expression required for tissue specification and axis formation. In Xenopus laevis , six nodal genes are expressed before gastrulation, raising the question of whether they have specific roles or act redundantly with each other. Here, we examine the role of Xnr5. We find it acts at the late blastula stage as a mesoderm inducer and repressor of ectodermal gene expression, a role it shares with Vg1. However, unlike Vg1, Xnr5 depletion reduces the expression of the nodal family member xnr1 at the gastrula stage. It is also required for left/right laterality by controlling the expression of the laterality genes xnr1, antivin ( lefty ) and pitx2 at the tailbud stage. In Xnr5-depleted embryos, the heart field is established normally, but symmetrical reduction in Xnr5 levels causes a severely stunted midline heart, first evidenced by a reduction in cardiac troponin mRNA levels, while left-sided reduction leads to randomization of the left/right axis. This work identifies Xnr5 as the earliest step in the signalling pathway establishing normal heart laterality in Xenopus .

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Hox and Tale transcription factors in heart development and disease

The International Journal of Developmental Biology ◽

10.1387/ijdb.180192sz ◽

2018 ◽

Vol 62 (11-12) ◽

pp. 837-846 ◽

Cited By ~ 8

Author(s):

Fabienne Lescroart ◽

Stephane Zaffran

Keyword(s):

Transcription Factors ◽

Congenital Heart Defects ◽

Heart Development ◽

Congenital Heart ◽

Hox Genes ◽

Heart Defects ◽

First Year ◽

First Year Of Life ◽

Cardiac Mesoderm

Hox genes are highly conserved transcription factors with critical functions during development, in particular for patterning the antero-posterior axis of the embryo. Their action is very often associated with cofactors including the TALE family transcription factors. From Drosophila to vertebrates, Hox genes have been shown to have a major role in heart development. In this review, we focus on the increasing evidence implicating the anterior Hox genes and the Tale family members during heart development both in the cardiac mesoderm and in neural crest cells. Congenital heart defects are the leading cause of death in the first year of life and a better understanding of the role of Hox and Tale factors is highly relevant to human pathologies and will provide novel mechanistic insights into the underlying defects.

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Abstract 16013: Direct Nkx2-5 Transcriptional Repression of Isl1 Controls Cardiomyocyte Subtype Identity

Circulation ◽

10.1161/circ.130.suppl_2.16013 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Alexander Goedel ◽

Tatjana Dorn ◽

Jason T Lam ◽

Franziska Herrmann ◽

Jessica Haas ◽

...

Keyword(s):

Heart Development ◽

Transcriptional Repression ◽

Embryonic Stem ◽

Cardiac Differentiation ◽

Heart Tube ◽

Cardiac Progenitors ◽

Gene Enhancer ◽

Heart Field ◽

Homeobox Protein ◽

Islet 1

During heart development the second heart field (SHF) provides progenitor cells for most cardiomyocytes and expresses the LIM-homeodomain transcription factor Islet-1 (Isl1) and the homeobox protein Nkx2-5. Here, we show that a direct repression of Isl1 transcription by Nkx2-5 is necessary for proper specification and maturation of ventricular and atrial chamber-specific myocardial lineages. Overexpression of Nkx2-5 in mouse embryonic stem cells (ESCs) delayed specification of cardiac progenitors and inhibited expression of Isl1 and its downstream targets in the Isl1+ precursor population. These effects were partially rescued by Isl1 overexpression. Embryos deficient for Nkx2-5 in the Isl1+ lineage failed to downregulate Isl1 protein in cardiomyocytes of the heart tube (Figure 1A). We demonstrated that Nkx2-5 directly binds to an Isl1 gene enhancer and represses the transcriptional activity of Isl1. Furthermore, we showed that overexpression of Isl1 does not prevent cardiac differentiation of ESCs and in Xenopus laevis embryos. Instead, Isl1 overexpression in ESCs leads to enhanced specification of cardiac progenitors, earlier cardiac differentiation, and increased number of cardiomyocytes (Figure 1B). Functional and molecular analysis of Isl1-overexpressing cardiomyocytes revealed higher beating frequencies in both ESC-derived contracting areas and Xenopus Isl1-gain-of-function hearts (Figure 1C), which was associated with upregulation of nodal-specific genes and downregulation of transcripts of working myocardium. Our findings provide an Isl1/Nkx2-5-mediated mechanism that coordinately regulates the specification of cardiac progenitors towards the different myocardial lineages and ensures proper acquisition of myocyte subtype-identity (Figure 1D).

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The role of cardiac transcription factor NKX2-5 in regulating the human cardiac miRNAome

Scientific Reports ◽

10.1038/s41598-019-52280-9 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Deevina Arasaratnam ◽

Katrina M. Bell ◽

Choon Boon Sim ◽

Kathy Koutsis ◽

David J. Anderson ◽

...

Keyword(s):

Mirna Expression ◽

Heart Development ◽

Regulatory Network ◽

Mirna Expression Profile ◽

Cardiac Progenitors ◽

Gene Regulatory ◽

Cardiac Transcription Factors ◽

Early Human ◽

Cardiac Mesoderm

Abstract MicroRNAs (miRNAs) are translational regulatory molecules with recognised roles in heart development and disease. Therefore, it is important to define the human miRNA expression profile in cardiac progenitors and early-differentiated cardiomyocytes and to determine whether critical cardiac transcription factors such as NKX2-5 regulate miRNA expression. We used an NKX2-5eGFP/w reporter line to isolate both cardiac committed mesoderm and cardiomyocytes. We identified 11 miRNAs that were differentially expressed in NKX2-5 -expressing cardiac mesoderm compared to non-cardiac mesoderm. Subsequent profiling revealed that the canonical myogenic miRNAs including MIR1-1, MIR133A1 and MIR208A were enriched in cardiomyocytes. Strikingly, deletion of NKX2-5 did not result in gross changes in the cardiac miRNA profile, either at committed mesoderm or cardiomyocyte stages. Thus, in early human cardiomyocyte commitment and differentiation, the cardiac myogenic miRNA program is predominantly regulated independently of the highly conserved NKX2-5 -dependant gene regulatory network.

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Targeted Inactivation of Serum Response Factor in the Developing Heart Results in Myocardial Defects and Embryonic Lethality

Molecular and Cellular Biology ◽

10.1128/mcb.24.12.5281-5289.2004 ◽

2004 ◽

Vol 24 (12) ◽

pp. 5281-5289 ◽

Cited By ~ 143

Author(s):

Ara Parlakian ◽

David Tuil ◽

Ghislaine Hamard ◽

Geneviève Tavernier ◽

Daniele Hentzen ◽

...

Keyword(s):

Heart Development ◽

Serum Response Factor ◽

Interventricular Septum ◽

Early Response ◽

Cardiac Differentiation ◽

Response Factor ◽

Transgenic Mouse Line ◽

Serum Response

ABSTRACT Serum response factor (SRF) is at the confluence of multiple signaling pathways controlling the transcription of immediate-early response genes and muscle-specific genes. There are active SRF target sequences in more than 50 genes expressed in the three muscle lineages including normal and diseased hearts. However, the role of SRF in heart formation has not been addressed in vivo thus far due to the early requirement of SRF for mesoderm formation. We have generated a conditional mutant of SRF by using Cre-LoxP strategy that will be extremely useful to study the role of SRF in embryonic and postnatal cardiac functions, as well as in other tissues. This report shows that heart-specific deletion of SRF in the embryo by using a new βMHC-Cre transgenic mouse line results in lethal cardiac defects between embryonic day 10.5 (E10.5) and E13.5, as evidenced by abnormally thin myocardium, dilated cardiac chambers, poor trabeculation, and a disorganized interventricular septum. At E9.5, we found a marked reduction in the expression of essential regulators of heart development, including Nkx2.5, GATA4, myocardin, and the SRF target gene c-fos prior to overt maldevelopment. We conclude that SRF is crucial for cardiac differentiation and maturation, acting as a global regulator of multiple developmental genes.

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The Ultrastructure of Myocardial Cells in Normal and Cardiac Lethal Mutant Mexican Axolotls, (Ambystoma Mexicanum)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067303 ◽

1970 ◽

Vol 28 ◽

pp. 62-63

Author(s):

Larry F. Lemanski ◽

Eldridge M. Bertke ◽

J. T. Justus

Keyword(s):

Fine Structure ◽

Heart Development ◽

Osmium Tetroxide ◽

Picric Acid ◽

Ambystoma Mexicanum ◽

Recessive Mutation ◽

Acid Mixture ◽

Myocardial Cells ◽

Lethal Mutant ◽

Mexican Axolotl

A recessive mutation has been recently described in the Mexican Axolotl, Ambystoma mexicanum; in which the heart forms structurally, but does not contract (Humphrey, 1968. Anat. Rec. 160:475). In this study, the fine structure of myocardial cells from normal (+/+; +/c) and cardiac lethal mutant (c/c) embryos at Harrison's stage 40 was compared. The hearts were fixed in a 0.1 M phosphate buffered formaldehyde-glutaraldehyde-picric acid-styphnic acid mixture and were post fixed in 0.1 M s-collidine buffered 1% osmium tetroxide. A detailed study of heart development in normal and mutant embryos from stages 25-46 will be described elsewhere.

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Faculty Opinions recommendation of Role of the MEOX2 homeobox gene in neurovascular dysfunction in Alzheimer disease.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1029489.345432 ◽

2005 ◽

Author(s):

Ivor Mason

Keyword(s):

Alzheimer Disease ◽

Homeobox Gene ◽

Neurovascular Dysfunction

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Altered DNA methylation pattern reveals epigenetic regulation of Hox genes in thoracic aortic dissection and serves as a biomarker in disease diagnosis

Clinical Epigenetics ◽

10.1186/s13148-021-01110-9 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Peiru Liu ◽

Jing Zhang ◽

Duo Du ◽

Dandan Zhang ◽

Zelin Jin ◽

...

Keyword(s):

Dna Methylation ◽

Aortic Dissection ◽

Epigenetic Regulation ◽

Heart Development ◽

Type A ◽

Methylation Pattern ◽

Healthy Controls ◽

Global Methylation ◽

Thoracic Aortic Dissection

Abstract Background Thoracic aortic dissection (TAD) is a severe disease with limited understandings in its pathogenesis. Altered DNA methylation has been revealed to be involved in many diseases etiology. Few studies have examined the role of DNA methylation in the development of TAD. This study explored alterations of the DNA methylation landscape in TAD and examined the potential role of cell-free DNA (cfDNA) methylation as a biomarker in TAD diagnosis. Results Ascending aortic tissues from TAD patients (Stanford type A; n = 6) and healthy controls (n = 6) were first examined via whole-genome bisulfite sequencing (WGBS). While no obvious global methylation shift was observed, numerous differentially methylated regions (DMRs) were identified, with associated genes enriched in the areas of vasculature and heart development. We further confirmed the methylation and expression changes in homeobox (Hox) clusters with 10 independent samples using bisulfite pyrosequencing and quantitative real-time PCR (qPCR). Among these, HOXA5, HOXB6 and HOXC6 were significantly down-regulated in TAD samples relative to controls. To evaluate cfDNA methylation pattern as a biomarker in TAD diagnosis, cfDNA from TAD patients (Stanford type A; n = 7) and healthy controls (n = 4) were examined by WGBS. A prediction model was built using DMRs identified previously from aortic tissues on methylation data from cfDNA. Both high sensitivity (86%) and specificity (75%) were achieved in patient classification (AUC = 0.96). Conclusions These findings showed an altered epigenetic regulation in TAD patients. This altered epigenetic regulation and subsequent altered expression of genes associated with vasculature and heart development, such as Hox family genes, may contribute to the loss of aortic integrity and TAD pathogenesis. Additionally, the cfDNA methylation in TAD was highly disease specific, which can be used as a non-invasive biomarker for disease prediction.

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