Downregulation of WT1 transcription factor gene expression is required to promote myocardial fate

During cardiac development, cells from the precardiac mesoderm fuse to form the primordial heart tube, which then grows by addition of further progenitors to the venous and arterial poles. In the zebrafish, wilms tumor 1 transcription factor a (wt1a) and b (wt1b) are expressed in the pericardial mesoderm at the venous pole of the forming heart tube. The pericardial mesoderm forms a single layered mesothelial sheet that contributes to further the growth of the myocardium, and forms the proepicardium. Proepicardial cells are subsequently transferred to the myocardial surface and give rise to the epicardium, the outer layer covering the myocardium in the adult heart. wt1a/b expression is downregulated during the transition from pericardium to myocardium, but remains high in proepicardial cells. Here we show that sustained wt1 expression impaired cardiomyocyte maturation including sarcomere assembly, ultimately affecting heart morphology and cardiac function. ATAC-seq data analysis of cardiomyocytes overexpressing wt1 revealed that chromatin regions associated with myocardial differentiation genes remain closed upon wt1b overexpression in cardiomyocytes, suggesting that wt1 represses a myocardial differentiation program. Indeed, a subset of wt1a/b-expressing cardiomyocytes changed their cell adhesion properties, delaminated from the myocardial epithelium, and upregulated the expression of epicardial genes, as confirmed by in vivo imaging. Thus, we conclude that wt1 acts as a break for cardiomyocyte differentiation by repressing chromatin opening at specific genomic loci and that sustained ectopic expression of wt1 in cardiomyocytes can lead to their transformation into epicardial cells.

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Transcription Factor Sp3 Knockout Mice Display Serious Cardiac Malformations

Molecular and Cellular Biology ◽

10.1128/mcb.01350-07 ◽

2007 ◽

Vol 27 (24) ◽

pp. 8571-8582 ◽

Cited By ~ 41

Author(s):

Pieter Fokko van Loo ◽

Edris A. F. Mahtab ◽

Lambertus J. Wisse ◽

Jun Hou ◽

Frank Grosveld ◽

...

Keyword(s):

Transcription Factor ◽

Heart Development ◽

Cardiac Development ◽

Expression Patterns ◽

Marker Genes ◽

Cardiac Malformations ◽

Epicardial Cells ◽

Developmental Hierarchy

ABSTRACT Mice lacking the zinc finger transcription factor specificity protein 3 (Sp3) die prenatally in the C57BL/6 background. To elucidate the cause of mortality we analyzed the potential role of Sp3 in embryonic heart development. Sp3 null hearts display defective looping at embryonic day 10.5 (E10.5), and at E14.5 the Sp3 null mutants have developed a range of severe cardiac malformations. In an attempt to position Sp3 in the cardiac developmental hierarchy, we analyzed the expression patterns of >15 marker genes in Sp3 null hearts. Expression of cardiac ankyrin repeat protein (Carp) was downregulated prematurely after E12.5, while expression of the other marker genes was not affected. Chromatin immunoprecipitation analysis revealed that Sp3 is bound to the Carp promoter region in vivo. Microarray analysis indicates that small-molecule metabolism and cell-cell interactions are the most significantly affected biological processes in E12.5 Sp3 null myocardium. Since the epicardium showed distension from the myocardium, we studied expression of Wt1, a marker for epicardial cells. Wt1 expression was diminished in epicardium-derived cells in the myocardium of Sp3 null hearts. We conclude that Sp3 is required for normal cardiac development and suggest that it has a crucial role in myocardial differentiation.

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IRF6 and TAK1 coordinately promote the activation of HIPK2 to stimulate apoptosis during palate fusion

Science Signaling ◽

10.1126/scisignal.aav7666 ◽

2019 ◽

Vol 12 (593) ◽

pp. eaav7666 ◽

Cited By ~ 2

Author(s):

Chen-Yeh Ke ◽

Hua-Hsuan Mei ◽

Fen-Hwa Wong ◽

Lun-Jou Lo

Keyword(s):

Transcription Factor ◽

Cell Apoptosis ◽

Transforming Growth Factor ◽

Kinase Inhibitor ◽

Ex Vivo ◽

Human Cancer ◽

Ectopic Expression ◽

Interacting Protein ◽

Human Cancer Cells

Cleft palate is a common craniofacial defect caused by a failure in palate fusion. The palatal shelves migrate toward one another and meet at the embryonic midline, creating a seam. Transforming growth factor–β3 (TGF-β3)–induced apoptosis of the medial edge epithelium (MEE), the cells located along the seam, is required for completion of palate fusion. The transcription factor interferon regulatory factor 6 (IRF6) promotes TGF-β3–induced MEE cell apoptosis by stimulating the degradation of the transcription factor ΔNp63 and promoting the expression of the gene encoding the cyclin-dependent kinase inhibitor p21. Because homeodomain-interacting protein kinase 2 (HIPK2) functions downstream of IRF6 in human cancer cells and is required for ΔNp63 protein degradation in keratinocytes, we investigated whether HIPK2 played a role in IRF6-induced ΔNp63 degradation in palate fusion. HIPK2 was present in the MEE cells of mouse palatal shelves during seam formation in vivo, and ectopic expression of IRF6 in palatal shelves cultured ex vivo stimulated the expression of Hipk2 and the accumulation of phosphorylated HIPK2. Knockdown and ectopic expression experiments in organ culture demonstrated that p21 was required for HIPK2- and IRF6-dependent activation of caspase 3, MEE apoptosis, and palate fusion. Contact between palatal shelves enhanced the phosphorylation of TGF-β–activated kinase 1 (TAK1), which promoted the phosphorylation of HIPK2 and palate fusion. Our findings demonstrate that HIPK2 promotes seam cell apoptosis and palate fusion downstream of IRF6 and that IRF6 and TAK1 appear to coordinately enhance the abundance and activation of HIPK2 during palate fusion.

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FOXO3a-driven miRNA signatures suppresses VEGF-A/NRP1 signaling and breast cancer metastasis

Oncogene ◽

10.1038/s41388-020-01562-y ◽

2020 ◽

Author(s):

Ying Song ◽

Shanshan Zeng ◽

Guopei Zheng ◽

Danyang Chen ◽

Pan Li ◽

...

Keyword(s):

Breast Cancer ◽

Transcription Factor ◽

Cancer Metastasis ◽

Critical Role ◽

Ectopic Expression ◽

Breast Cancer Metastasis ◽

Metastasis Suppressor ◽

Breast Cancer Patients ◽

Signaling Axis

AbstractMetastasis remains the major obstacle to improved survival for breast cancer patients. Downregulation of FOXO3a transcription factor in breast cancer is causally associated with the development of metastasis through poorly understood mechanisms. Here, we report that FOXO3a is functionally related to the inhibition of VEGF-A/NRP1 signaling and to the consequent suppression of breast cancer metastasis. We show that FOXO3a directly induces miR-29b-2 and miR-338 expression. Ectopic expression of miR-29b-2/miR-338 significantly suppresses EMT, migration/invasion, and in vivo metastasis of breast cancer. Moreover, we demonstrate that miR-29b-2 directly targets VEGF-A while miR-338 directly targets NRP1, and show that regulation of miR-29b-2 and miR-338 mediates the ability of FOXO3a to suppress VEGF-A/NRP1 signaling and breast cancer metastasis. Clinically, our results show that the FOXO3a-miR-29b-2/miR-338-VEGF-A/NRP1 axis is dysregulated and plays a critical role in disease progression in breast cancer. Collectively, our findings propose that FOXO3a functions as a metastasis suppressor, and define a novel signaling axis of FOXO3a-miRNA-VEGF-A/NRP1 in breast cancer, which might be potential therapeutic targets for breast cancer.

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Notch1 co-opts lymphoid enhancer factor 1 for survival of murine T-cell lymphomas

Blood ◽

10.1182/blood-2007-04-084202 ◽

2007 ◽

Vol 110 (7) ◽

pp. 2650-2658 ◽

Cited By ~ 30

Author(s):

Christina Spaulding ◽

Erica J. Reschly ◽

Derek E. Zagort ◽

Yumi Yashiro-Ohtani ◽

Levi J. Beverly ◽

...

Keyword(s):

Transcription Factor ◽

T Cell ◽

Cell Lymphoma ◽

Ectopic Expression ◽

Malignant Cell ◽

T Cell Lymphomas ◽

Notch1 Mutations ◽

Enhancer Factor

Oncogenic Notch1 mutations are found in most T-lineage acute lymphoblastic leukemias in humans and T-cell lymphomas in mice. However, the mechanism by which Notch1 promotes transformation or maintains malignant cell survival has not been determined fully. Here, we report that expression of the transcription factor lymphoid enhancer factor 1 (Lef1) is Notch dependent in murine T-cell lymphomas in vitro and in vivo, and that the intracellular domain of Notch1 (ICN1) is present at the Lef1 promoter. Lef1 expression is not Notch dependent in primary T-cell progenitors, but Lef1 mRNA is increased by ectopic expression of ICN1 in these cells. We show that Lef1 is required for survival of T-cell lymphoma lines, and that ectopic expression of Lef1 delays lymphoma cell death in the absence of Notch signaling, indicating that Lef1 is an important Notch target in these cells. Therefore, Notch1 co-opts Lef1 during the process of transformation to maintain survival of T-cell lymphomas.

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In vitro generation of HSC-like cells from murine ESCs/iPSCs by enforced expression of LIM-homeobox transcription factor Lhx2

Blood ◽

10.1182/blood-2010-07-298596 ◽

2011 ◽

Vol 117 (14) ◽

pp. 3748-3758 ◽

Cited By ~ 37

Author(s):

Kenji Kitajima ◽

Ken-ichi Minehata ◽

Kenji Sakimura ◽

Toru Nakano ◽

Takahiko Hara

Keyword(s):

Stem Cells ◽

Transcription Factor ◽

Ectopic Expression ◽

Hematopoietic Cells ◽

Embryonic Stem ◽

Hematopoietic Stem ◽

Homeobox Transcription Factor ◽

Induced Pluripotent

Abstract Identification of genes involved in in vitro differentiation induction of embryonic stem cells (ESCs) into hematopoietic stem cells (HSCs) has been challenged during last decade. To date, a homeobox transcription factor Hoxb4 has been only demonstrated to possess such an effect in mice. Here, we show that HSC-like cells were efficiently induced from mouse ESCs by enforced expression of Lhx2, a LIM-homeobox transcription factor. Transduction of Lhx2 into ESC-derived mesodermal cells resulted in robust differentiation of c-Kit+/Sca-1+/Lineage− (KSL) cells in vitro. The KSL cell induction frequency was superior to the case of Hoxb4. Furthermore, transplantation of Lhx2-transduced hematopoietic cells into lethally irradiated mice resulted in multilineage repopulation of hematopoietic cells over 4 months. Transduction of Lhx2 into induced pluripotent stem cells (iPSCs) was also effective in generating KSL cells in vitro, as well as HSC-like activities in vivo. These results demonstrate that ectopic expression of Lhx2 confers an in vivo engrafting capacity to ESC/iPSC-derived hematopoietic cells and in vivo behavior of iPSC-derived hematopoietic cells is almost identical to that of ESC-derived cells.

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Resolving titin’s lifecycle and the spatial organization of protein turnover in mouse cardiomyocytes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1904385116 ◽

2019 ◽

Vol 116 (50) ◽

pp. 25126-25136 ◽

Cited By ~ 3

Author(s):

Franziska Rudolph ◽

Judith Hüttemeister ◽

Katharina da Silva Lopes ◽

René Jüttner ◽

Lily Yu ◽

...

Keyword(s):

Spatial Organization ◽

Cardiac Development ◽

Protein Composition ◽

Protein Pool ◽

Embryonic Cardiomyocytes ◽

Sarcomere Assembly ◽

Protein Synthesis And Degradation ◽

Knockin Mouse ◽

Synthesis And Degradation

Cardiac protein homeostasis, sarcomere assembly, and integration of titin as the sarcomeric backbone are tightly regulated to facilitate adaptation and repair. Very little is known on how the >3-MDa titin protein is synthesized, moved, inserted into sarcomeres, detached, and degraded. Here, we generated a bifluorescently labeled knockin mouse to simultaneously visualize both ends of the molecule and follow titin’s life cycle in vivo. We find titin mRNA, protein synthesis and degradation compartmentalized toward the Z-disk in adult, but not embryonic cardiomyocytes. Originating at the Z-disk, titin contributes to a soluble protein pool (>15% of total titin) before it is integrated into the sarcomere lattice. Titin integration, disintegration, and reintegration are stochastic and do not proceed sequentially from Z-disk to M-band, as suggested previously. Exchange between soluble and integrated titin depends on titin protein composition and differs between individual cardiomyocytes. Thus, titin dynamics facilitate embryonic vs. adult sarcomere remodeling with implications for cardiac development and disease.

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Cell-cell contact regulates gene expression in CDK4-transformed mouse podocytes

AJP Renal Physiology ◽

10.1152/ajprenal.00205.2010 ◽

2010 ◽

Vol 299 (4) ◽

pp. F802-F809 ◽

Cited By ~ 10

Author(s):

Toru Sakairi ◽

Yoshifusa Abe ◽

Parmijit S. Jat ◽

Jeffrey B. Kopp

Keyword(s):

Gene Expression ◽

Mrna Expression ◽

Wilms Tumor ◽

Ectopic Expression ◽

T Antigen ◽

Marker Genes ◽

Cell Contact ◽

Sv40 Large T Antigen ◽

Cell Cell

We transformed mouse podocytes by ectopic expression of cyclin-dependent kinase 4 (CDK4). Compared with podocytes transformed with a thermo-sensitive SV40 large T antigen mutant tsA58U19 (tsT podocytes), podocytes transformed with CDK4 (CDK4 podocytes) exhibited significantly higher expression of nephrin mRNA. Synaptopodin mRNA expression was significantly lower in CDK4 podocytes and in tsT podocytes under growth-permissive conditions (33°C) compared with tsT podocytes under growth-restricted conditions (37°C), which suggests a role for cell cycle arrest in synaptopodin mRNA expression. Confluent CDK4 podocytes showed significantly higher mRNA expression levels for nephrin, synaptopodin, Wilms tumor 1, podocalyxin, and P-cadherin compared with subconfluent cultures. We carried out experiments to clarify roles of various factors in the confluent podocyte cultures; our findings indicate that cell-cell contact promotes expression of five podocyte marker genes studied, that cellular quiescence increases synaptopodin and podocalyxin mRNA expression, and that soluble factors play a role in nephrin mRNA expression. Our findings suggest that CDK4 podocytes are useful tools to study podocyte biology. Furthermore, the role of cell-cell contact in podocyte gene expression may have relevance for podocyte function in vivo.

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