Cell shape, intracellular pH, and fibroblast growth factor responsiveness during transdifferentiation of retinal pigment epithelium into neuroepithelium in vitro

1994 ◽  
Vol 72 (7-8) ◽  
pp. 257-265 ◽  
Author(s):  
You Zhou ◽  
Michal Opas
Keyword(s):  
Growth Factor ◽  
Retinal Pigment Epithelium ◽  
Fibroblast Growth Factor ◽  
Intracellular Ph ◽  
Basic Fibroblast Growth Factor ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cell Sheet ◽  
Fibroblast Growth ◽  
Rpe Cells

In this report we show that some retinal pigment epithelial (RPE) cells, with no expression of neural cell adhesion molecule (N-CAM) [Formula: see text], spontaneously lose pigment and start to express N-CAM in culture. Chick RPE cells normally do not express N-CAM, while the protein is present in chick neural retina. Thus some of the RPE cells in culture started to transdifferentiate into a neuroepithelium[Formula: see text]. We have measured intracellular pH (pHi) in the RPE cultures and followed its changes in response to basic fibroblast growth factor (bFGF). The depigmented cells protrude above the RPE cell sheet and have a lower resting pHi (≈7.05) than the pigmented RPE cells (≈7.15). The majority of cells with low resting pHi express N-CAM. The difference in the resting pHi between [Formula: see text]and [Formula: see text] cells is not due to the N-CAM expression by [Formula: see text] cells, as their pHi is the same as the pHi of freshly plated single "round" [Formula: see text] cells that have not spread yet. [Formula: see text] cells respond to bFGF with a quick and sustained pHi rise. In contrast, neither the cuboidal [Formula: see text] cells in a colony centre nor single round [Formula: see text] cells respond to bFGF with cytoplasmic alkalinization. RPE cells do not proliferate in response to bFGF, while NE cells respond to bFGF with a stimulation of growth. We conclude that bFGF acts not on the fully differentiated [Formula: see text], but only on those cells which have already started to transdifferentiate and changed their shape and (or) adhesive status. bFGF provides [Formula: see text] cells that transdifferentiated from [Formula: see text] cells with a signal necessary to transdifferentiate and (or) histodifferentiate further.Key words: retinal pigment epithelium, retina, transdifferentiation, intracellular pH, basic fibroblast growth factor.

scholarly journals Differential induction of gene expression by basic fibroblast growth factor and neuroD in cultured retinal pigment epithelial cells

2000 ◽  
Vol 17 (2) ◽  
pp. 157-164 ◽  
Author(s):  
RUN-TAO YAN ◽  
SHU-ZHEN WANG
Keyword(s):  
Gene Expression ◽  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Fibroblast Growth ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Two Factors

Embryonic chick retinal pigment epithelial (RPE) cells can undergo transdifferentiation upon appropriate stimulation. For example, basic fibroblast growth factor (bFGF) induces intact RPE tissue younger than embryonic day 4.5 (E4.5) to transdifferentiate into a neural retina. NeuroD, a gene encoding a basic helix-loop–helix transcription factor, triggers de novo production of cells that resemble young photoreceptor cells morphologically and express general neuron markers (HNK-1/N-CAM and MAP2) and a photoreceptor-specific marker (visinin) from cell cultures of dissociated E6 RPE (Yan & Wang, 1998). The present study examined whether bFGF will lead to the same transdifferentiation phenomenon as neuroD when applied to dissociated, cultured E6 RPE cells, and whether interplay exists between the two factors under the culture conditions. Dissociated E6 RPE cells were cultured in the presence or absence of bFGF, and with or without the addition of retrovirus expressing neuroD. Gene expression was analyzed with immunocytochemistry and in situ hybridization. Unlike neuroD, bFGF did not induce the expression of visinin, or HNK-1/N-CAM and MAP2. However, bFGF elicited the expression of RA4 immunogenicity; yet, many of these RA4-positive cells lacked a neuronal morphology. Addition of bFGF to neuroD-expressing cultures did not alter the number of visinin-expressing cells; misexpression of neuroD in bFGF-treated cultures did not change the number of RA4-positive cells, suggesting the absence of interference or synergistic interaction between the two factors. Our data indicated that bFGF and neuroD induced the expression of different genes in cultured RPE cells.

Basic fibroblast growth factor induces retinal pigment epithelium to generate neural retina in vitro

Development ◽  
1991 ◽  
Vol 113 (2) ◽  
pp. 577-588 ◽  
Author(s):  
C. Pittack ◽  
M. Jones ◽  
T.A. Reh
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Retinal Pigment ◽  
Neural Retina ◽  
Phenotypic Switching ◽  
Surgical Removal ◽  
Fibroblast Growth ◽  
Neuronal Progenitors

During embryogenesis, the cells of the eye primordium are initially capable of giving rise to either neural retina or pigmented epithelium (PE), but become restricted to one of these potential cell fates. However, following surgical removal of the retina in embryonic chicks and larval amphibians, new neural retina is generated by the transdifferentiation, or phenotypic switching, of PE cells into neuronal progenitors. A recent study has shown that basic fibroblast growth factor (bFGF) stimulates this process in chicks in vivo. To characterize further the mechanisms by which this factor regulates the phenotype of retinal tissues, we added bFGF to enzymatically dissociated chick embryo PE. We found that bFGF stimulated proliferation and caused several morphological changes in the PE, including the loss of pigmentation; however, no transdifferentiation to neuronal phenotypes was observed. By contrast, when small sheets of PE were cultured as aggregates on a shaker device, preventing flattening and spreading on the substratum, we found that a large number of retinal progenitor cells were generated from the PE treated with bFGF. These results indicate that bFGF promotes retinal regeneration in vitro, as well as in ovo, and suggest that the ability of chick PE to undergo transdifferentiation to neuronal progenitors appears to be dependent on the physical configuration of the cells.

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