Nf2 fine-tunes proliferation and tissue alignment during closure of the optic fissure in the embryonic mouse eye

Abstract Uveal coloboma represents one of the most common congenital ocular malformations accounting for up to 10% of childhood blindness (~1 in 5000 live birth). Coloboma originates from defective fusion of the optic fissure (OF), a transient gap that forms during eye morphogenesis by asymmetric, ventral invagination. Genetic heterogeneity combined with the activity of developmentally regulated genes suggests multiple mechanisms regulating OF closure. The tumor suppressor and FERM domain protein Neurofibromin 2 (NF2) controls diverse processes in cancer, development and regeneration, via Hippo pathway and cytoskeleton regulation. In humans, NF2 mutations can cause ocular abnormalities, including coloboma, however, its actual role in OF closure is unknown. Using conditional inactivation in the embryonic mouse eye, our data indicate that loss of Nf2 function results in a novel underlying cause for coloboma. In particular, mutant eyes show substantially increased retinal pigmented epithelium (RPE) proliferation in the fissure region with concomitant acquisition of RPE cell fate. Cells lining the OF margin can maintain RPE fate ectopically and fail to transition from neuroepithelial to cuboidal shape. In the dorsal RPE of the optic cup, Nf2 inactivation leads to a robust increase in cell number, with local disorganization of the cytoskeleton components F-actin and pMLC2. We propose that RPE hyperproliferation is the primary cause for the observed defects causing insufficient alignment of the OF margins in Nf2 mutants and failure to fuse properly, resulting in persistent coloboma. Our findings indicate that limiting proliferation particularly in the RPE layer is a critical mechanism during OF closure.

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Nf2 fine-tunes proliferation and tissue alignment during closure of the optic fissure in the embryonic mouse eye

10.1101/2020.06.28.176065 ◽

2020 ◽

Author(s):

Wesley R. Sun ◽

Sara Ramirez ◽

Kelly E. Spiller ◽

Yan Zhao ◽

Sabine Fuhrmann

Keyword(s):

Cell Fate ◽

Hippo Pathway ◽

Cell Number ◽

Cancer Development ◽

Developmentally Regulated ◽

Ferm Domain ◽

Embryonic Mouse ◽

Ocular Abnormalities ◽

Optic Cup ◽

Eye Morphogenesis

AbstractUveal coloboma represents one of the most common congenital ocular malformations accounting for up to 10% of childhood blindness (1~ in 5,000 live birth). Coloboma originates from defective fusion of the optic fissure (OF), a transient gap that forms during eye morphogenesis by asymmetric, ventral invagination. Genetic heterogeneity combined with the activity of developmentally regulated genes suggest multiple mechanisms regulating OF closure. The tumor suppressor and FERM domain protein neurofibromin 2 (NF2) controls diverse processes in cancer, development and regeneration, via Hippo pathway and cytoskeleton regulation. In humans, NF2 mutations can cause ocular abnormalities, including coloboma, however, its actual role in OF closure is unknown. Using conditional inactivation in the embryonic mouse eye, our data indicates that loss of Nf2 function results in a novel underlying cause for coloboma. In particular, mutant eyes show substantially increased RPE proliferation in the fissure region with concomitant acquisition of RPE cell fate. Cells lining the OF margin can maintain RPE fate ectopically and fail to transition from neuroepithelial to cuboidal shape. In the dorsal RPE of the optic cup, Nf2 inactivation leads to a robust increase in cell number, with local disorganization of the cytoskeleton components F-actin and pMLC2. We propose that RPE hyperproliferation is the primary cause for the observed defects causing insufficient alignment of the OF margins in Nf2 mutants and failure to fuse properly, resulting in persistent coloboma. Our findings indicate that limiting proliferation particularly in the RPE layer is a critical mechanism during optic fissure closure.

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Epithelial flow into the optic cup facilitated by suppression of BMP drives eye morphogenesis

10.1101/010165 ◽

2014 ◽

Author(s):

Stephan Heermann ◽

Lucas Schuetz ◽

Steffen Lemke ◽

Kerstin Krieglstein ◽

Joachim Wittbrodt

Keyword(s):

Morphological Changes ◽

Fold Increase ◽

Optic Vesicle ◽

Retinal Pigmented Epithelium ◽

Basal Surface ◽

Classical View ◽

Optic Cup ◽

Pigmented Epithelium ◽

Vertebrate Eye ◽

Eye Morphogenesis

The transformation of the oval optic vesicle to a hemispheric bi-layered optic cup involves major morphological changes during early vertebrate eye development. According to the classical view, the lens-averted epithelium differentiates into the retinal pigmented epithelium (RPE), while the lens-facing epithelium forms the neuroretina. We find a 4.7 fold increase of the entire basal surface of the optic cup. Although the area an individual RPC demands at its basal surface declines during optic cup formation, we find a 4.7 fold increase of the entire basal surface of the optic cup. We demonstrate that the lens-averted epithelium functions as reservoir and contributes to the growing neuroretina by epithelial flow around the distal rims of the optic cup. This flow is negatively modulated by BMP, which arrests epithelial flow. This inhibition results in persisting neuroretina in the RPE domain and ultimately in coloboma.

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Localization of Tfap2β, Casq2, Penk, Zic1, and Zic3 Expression in the Developing Retina, Muscle, and Sclera of the Embryonic Mouse Eye

Journal of Histochemistry & Cytochemistry ◽

10.1369/0022155419885112 ◽

2019 ◽

Vol 67 (12) ◽

pp. 863-871

Author(s):

Yong Wan ◽

Casey White ◽

Nadine Robert ◽

Matthew B. Rogers ◽

Heather L. Szabo-Rogers

Keyword(s):

Calcium Binding ◽

Expression Patterns ◽

Cell Types ◽

Neural Retina ◽

Craniofacial Development ◽

Optic Disk ◽

Embryonic Mouse ◽

Optic Cup ◽

Unique Cell ◽

Eye Morphogenesis

Optic development involves sequential interactions between several different tissue types, including the overlying ectoderm, adjacent mesoderm, and neural crest mesenchyme and the neuroectoderm. In an ongoing expression screen, we identified that Tfap2β, Casq2, Penk, Zic1, and Zic3 are expressed in unique cell types in and around the developing eye. Tfap2β, Zic1, and Zic3 are transcription factors, Casq2 is a calcium binding protein and Penk is a neurotransmitter. Tfap2β, Zic1, and Zic3 have reported roles in brain and craniofacial development, while Casq2 and Penk have unknown roles. These five genes are expressed in the major tissue types in the eye, including the muscles, nerves, cornea, and sclera. Penk expression is found in the sclera and perichondrium. At E12.5 and E15.5, the extra-ocular muscles express Casq2, the entire neural retina expresses Zic1, and Zic3 is expressed in the optic disk and lip of the optic cup. The expression of Tfap2β expanded from corneal epithelium to the neural retina between E12.5 to E15.5. These genes are expressed in similar domains as Hedgehog ( Gli1, and Ptch1) and the Wnt ( Lef1) pathways. The expression patterns of these five genes warrant further study to determine their role in eye morphogenesis:

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A role for the fusogen eff-1 in epidermal stem cell number robustness in Caenorhabditis elegans

Scientific Reports ◽

10.1038/s41598-021-88500-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sneha L. Koneru ◽

Fu Xiang Quah ◽

Ritobrata Ghose ◽

Mark Hintze ◽

Nicola Gritti ◽

...

Keyword(s):

Stem Cell ◽

Caenorhabditis Elegans ◽

Cell Fate ◽

Single Molecule ◽

Phenotypic Variability ◽

Low Frequency ◽

Time Lapse ◽

Cell Number ◽

Seam Cell ◽

Neuronal Tissues

AbstractDevelopmental patterning in Caenorhabditis elegans is known to proceed in a highly stereotypical manner, which raises the question of how developmental robustness is achieved despite the inevitable stochastic noise. We focus here on a population of epidermal cells, the seam cells, which show stem cell-like behaviour and divide symmetrically and asymmetrically over post-embryonic development to generate epidermal and neuronal tissues. We have conducted a mutagenesis screen to identify mutants that introduce phenotypic variability in the normally invariant seam cell population. We report here that a null mutation in the fusogen eff-1 increases seam cell number variability. Using time-lapse microscopy and single molecule fluorescence hybridisation, we find that seam cell division and differentiation patterns are mostly unperturbed in eff-1 mutants, indicating that cell fusion is uncoupled from the cell differentiation programme. Nevertheless, seam cell losses due to the inappropriate differentiation of both daughter cells following division, as well as seam cell gains through symmetric divisions towards the seam cell fate were observed at low frequency. We show that these stochastic errors likely arise through accumulation of defects interrupting the continuity of the seam and changing seam cell shape, highlighting the role of tissue homeostasis in suppressing phenotypic variability during development.

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Build me up optic cup: Intrinsic and extrinsic mechanisms of vertebrate eye morphogenesis

Developmental Biology ◽

10.1016/j.ydbio.2021.03.023 ◽

2021 ◽

Vol 476 ◽

pp. 128-136

Author(s):

Macaulie A. Casey ◽

Sarah Lusk ◽

Kristen M. Kwan

Keyword(s):

Optic Cup ◽

Vertebrate Eye ◽

Eye Morphogenesis

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YAP and endothelin-1 signaling: an emerging alliance in cancer

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-021-01827-8 ◽

2021 ◽

Vol 40 (1) ◽

Author(s):

Piera Tocci ◽

Giovanni Blandino ◽

Anna Bagnato

Keyword(s):

Signaling Pathways ◽

Cell Fate ◽

Therapeutic Option ◽

Hippo Pathway ◽

Signaling Network ◽

Nuclear Accumulation ◽

Binding Motif ◽

Mutant P53 ◽

Endothelin 1 ◽

The Hippo Pathway

AbstractThe rational making the G protein-coupled receptors (GPCR) the centerpiece of targeted therapies is fueled by the awareness that GPCR-initiated signaling acts as pivotal driver of the early stages of progression in a broad landscape of human malignancies. The endothelin-1 (ET-1) receptors (ET-1R), known as ETA receptor (ETAR) and ETB receptor (ETBR) that belong to the GPCR superfamily, affect both cancer initiation and progression in a variety of cancer types. By the cross-talking with multiple signaling pathways mainly through the scaffold protein β-arrestin1 (β-arr1), ET-1R axis cooperates with an array of molecular determinants, including transcription factors and co-factors, strongly affecting tumor cell fate and behavior. In this scenario, recent findings shed light on the interplay between ET-1 and the Hippo pathway. In ETAR highly expressing tumors ET-1 axis induces the de-phosphorylation and nuclear accumulation of the Hippo pathway downstream effectors, the paralogous transcriptional cofactors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). Recent evidence have discovered that ET-1R/β-arr1 axis instigates a transcriptional interplay involving YAP and mutant p53 proteins, which share a common gene signature and cooperate in a oncogenic signaling network. Mechanistically, YAP and mutp53 are enrolled in nuclear complexes that turn on a highly selective YAP/mutp53-dependent transcriptional response. Notably, ET-1R blockade by the FDA approved dual ET-1 receptor antagonist macitentan interferes with ET-1R/YAP/mutp53 signaling interplay, through the simultaneous suppression of YAP and mutp53 functions, hampering metastasis and therapy resistance. Based on these evidences, we aim to review the recent findings linking the GPCR signaling, as for ET-1R, to YAP/TAZ signaling, underlining the clinical relevance of the blockade of such signaling network in the tumor and microenvironmental contexts. In particular, we debate the clinical implications regarding the use of dual ET-1R antagonists to blunt gain of function activity of mutant p53 proteins and thereby considering them as a potential therapeutic option for mutant p53 cancers. The identification of ET-1R/β-arr1-intertwined and bi-directional signaling pathways as targetable vulnerabilities, may open new therapeutic approaches able to disable the ET-1R-orchestrated YAP/mutp53 signaling network in both tumor and stromal cells and concurrently sensitizes to high-efficacy combined therapeutics.

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EFFECTS OF CYCLIC AMP AND SEPHADEX FRACTIONS OF CHICK EMBRYO EXTRACT ON CLONED RETINAL PIGMENTED EPITHELIUM IN TISSUE CULTURE

The Journal of Cell Biology ◽

10.1083/jcb.61.2.369 ◽

1974 ◽

Vol 61 (2) ◽

pp. 369-382 ◽

Cited By ~ 28

Author(s):

D. A. Newsome ◽

R. T. Fletcher ◽

W. G. Robison ◽

K. R. Kenyon ◽

G. J. Chader

Keyword(s):

Molecular Weight ◽

Chick Embryo ◽

Adenosine Monophosphate ◽

Cell Number ◽

Retinal Pigmented Epithelium ◽

Culture Dish ◽

Adhesive Properties ◽

Embryo Extract ◽

Chick Embryo Extract ◽

Pigmented Epithelium

The effects of dibutyryl cyclic 3',5'-adenosine monophosphate (BcAMP) and Sephadex G-25 fractions of chick embryo extract on the growth rate, morphology, and pigmentation of normal chick retinal pigmented epithelium (PE) were investigated. Seven cloned PE cell lines were each grown in modified Ham's F-12 medium alone (F-12), or in F-12 supplemented with either high molecular weight (H) or low molecular weight (L) fractions of chick embryo extract. Cells grown in F-12 alone or in L medium formed compact epithelial sheets, whereas cells grown in H had a fibrocytic appearance and formed poorly organized monolayers. In H plus BcAMP, cell morphology was more epithelioid than in H alone, and generally the monolayers appeared more differentiated. Under each of these three culture conditions, 2 x 10-4 M BCAMP retarded the increase in cell number and decreased the final number of cells per culture dish, but had little effect on plating efficiency. BcAMP also increased the rate of cell adhesion to a plastic substratum. Pigmentation was marked in cultures grown in F-12 or in L alone, but the addition of BcAMP dramatically reduced visible pigmentation. This effect was reversed when BcAMP was removed from the culture medium. Thus BcAMP modifies cell and colonial morphology, rate of cell accumulation, adhesive properties, and pigmentation of normal PE cells.

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The Hippo Pathway: A Master Regulatory Network Important in Cancer

Cells ◽

10.3390/cells10061416 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1416

Author(s):

Qiuping Liu ◽

Xiaomeng Liu ◽

Guanbin Song

Keyword(s):

Metabolic Regulation ◽

Human Cancer ◽

Hippo Pathway ◽

Tumor Development ◽

Biological Significance ◽

Cancer Development ◽

Hippo Signaling ◽

Complex Regulation ◽

And Function ◽

The Hippo Pathway

The Hippo pathway is pervasively activated and has been well recognized to play critical roles in human cancer. The deregulation of Hippo signaling involved in cancer development, progression, and resistance to cancer treatment have been confirmed in several human cancers. Its biological significance and deregulation in cancer have drawn increasing interest in the past few years. A fundamental understanding of the complexity of the Hippo pathway in cancer is crucial for improving future clinical interventions and therapy for cancers. In this review, we try to clarify the complex regulation and function of the Hippo signaling network in cancer development, including its role in signal transduction, metabolic regulation, and tumor development, as well as tumor therapies targeting the Hippo pathway.

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