Transdifferentiation of chicken embryo neural retina into pigment epithelium: indications of its biochemical basis

Development ◽  
1981 ◽  
Vol 62 (1) ◽  
pp. 47-62
Author(s):  
D. J. Pritchard
Keyword(s):  
Pigment Cell ◽  
Pigment Epithelium ◽  
Cell Formation ◽  
Tca Cycle ◽  
Cell Types ◽  
Neural Retina ◽  
Pigment Cells ◽  
Biochemical Basis ◽  
Pigment Synthesis

Neural retina from 8- to 9-day embryo chickens was grown in long-term cell culture in an experiment to test the hpothesis that one step during the in vitro transdifferentiation of neural retina into pigment cells occurs in response to stimulation of tricarboxylic acid (TCA) cycle activity. Time-lapse photography showed that pigment-cell formation occurs through the intermediate stages of ‘undistinguished cells’, ‘pavement epithelium’ and ‘potential pigment cells’. Mitosis of undistinguished cells to pavement epithelium was proportional to malonate over most of the tested range of concentrations and was inhibited by succinate, which respectively depress and stimulate the TCA cycle. Conversely mitosis of pavement epithelium to potential pigment cells occurred in proportion to succinate concentration over most of the tested range and was inhibited by malonate, in support of the hypothesis under test. Melanin synthesis begins in a minority of ‘pigment leader cells’ uniquely stimulated by the lowest concentration of malonate, although higher concentrations blocked pigment synthesis in all cell types. The pigment leader cells appear to act as centres of influence upon neighbouring potential pigment cells, which subsequently also beome pigmented. Lactate inhibited most or all of the steps in formation of pigment epithelium. Between three and five mitoses occur in the production of pigment cells, whereas multilayers and lentoid bodies seem to be formed by expansion of undistinguished cells, probably without mitosis. The observations lead to a general theory that metaplastic conversion between cell types in eye tissues may require the physical isolation of overtly differentiated, multipotent cells from ‘leader’ cells which normally hold them in physiological subjugation.

‘Transdifferentiation’ of chicken neural retina into lens and pigment epithelium in culture: controlling influences

Development ◽  
1978 ◽  
Vol 48 (1) ◽  
pp. 1-21
Author(s):  
D. J. Pritchard ◽  
R. M. Clayton ◽  
D. I. De Pomerai
Keyword(s):  
Pigment Cell ◽  
Pigment Epithelium ◽  
Neural Retina ◽  
Medium Composition ◽  
Pigment Cells ◽  
Bicarbonate Concentration ◽  
Experimental Conditions ◽  
Culture Growth ◽  
New Hypothesis

The in vitro transdifferentiation of chicken embryo neural retina into pigment epithelium and lens cells was investigated under a variety of experimental conditions. Our findings suggest that some aspects of the phenomena are a function of medium composition and volume, whereas others depend upon conditions which develop during culture growth. Before melanin is visible, potential pigment cells are recognized as foci within epithelialsheets which remain in contact with the dish. The final area occupied by colonies of potential pigment cells is directly proportional to bicarbonate concentration. Low total medium volume also favours formation of potential pigment cells. In contrast the extent of cells other than potential pigment cells is not related to bicarbonate and is favoured when the volume of medium is large. Accumulation of melanin within the potential pigment cell colonies is suppressed when cells are crowded together. Lentoid bodies are formed from cells which are distinct from potential pigment cells and arise in crowded situations, in association with multilayering. Another type of structure superficially resembling a lentoid is derived from cell aggregates formed during the initial establishment of cultures. The survival of these ‘aggregate bodies’ is inversely related to bicarbonate concentration. Crystallin content is unrelated to lentoid numbers. The results provide the basis for a new hypothesis concerning cytodifferentiation in this system.

nacre encodes a zebrafish microphthalmia-related protein that regulates neural-crest-derived pigment cell fate

Development ◽  
1999 ◽  
Vol 126 (17) ◽  
pp. 3757-3767 ◽  
Author(s):  
J.A. Lister ◽  
C.P. Robertson ◽  
T. Lepage ◽  
S.L. Johnson ◽  
D.W. Raible
Keyword(s):  
Transcription Factor ◽  
Retinal Pigment Epithelium ◽  
Neural Crest ◽  
Cell Fate ◽  
Pigment Cell ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Pigment Cells ◽  
Evolutionary Divergence ◽  
Wild Type

We report the isolation and identification of a new mutation affecting pigment cell fate in the zebrafish neural crest. Homozygous nacre (nac(w2)) mutants lack melanophores throughout development but have increased numbers of iridophores. The non-crest-derived retinal pigment epithelium is normal, suggesting that the mutation does not affect pigment synthesis per se. Expression of early melanoblast markers is absent in nacre mutants and transplant experiments suggested a cell-autonomous function in melanophores. We show that nac(w2) is a mutation in a zebrafish gene encoding a basic helix-loop-helix/leucine zipper transcription factor related to microphthalmia (Mitf), a gene known to be required for development of eye and crest pigment cells in the mouse. Transient expression of the wild-type nacre gene restored melanophore development in nacre(−/−) embryos. Furthermore, misexpression of nacre induced the formation of ectopic melanized cells and caused defects in eye development in wild-type and mutant embryos. These results demonstrate that melanophore development in fish and mammals shares a dependence on the nacre/Mitf transcription factor, but that proper development of the retinal pigment epithelium in the fish is not nacre-dependent, suggesting an evolutionary divergence in the function of this gene.

scholarly journals KCNQ5/Kv7.5 potassium channel expression and subcellular localization in primate retinal pigment epithelium and neural retina

2011 ◽  
Vol 301 (5) ◽  
pp. C1017-C1026 ◽  
Author(s):  
Xiaoming Zhang ◽  
Dongli Yang ◽  
Bret A. Hughes
Keyword(s):  
Visual Information ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Basal Membrane ◽  
Cell Types ◽  
Neural Retina ◽  
Pcr Analysis ◽  
Rod Photoreceptor ◽  
Rpe Cells ◽  
Channel Expression

Previous studies identified in retinal pigment epithelial (RPE) cells an M-type K+ current, which in many other cell types is mediated by channels encoded by KCNQ genes. The aim of this study was to assess the expression of KCNQ genes in the monkey RPE and neural retina. Application of the specific KCNQ channel blocker XE991 eliminated the M-type current in freshly isolated monkey RPE cells, indicating that KCNQ subunits contribute to the underlying channels. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE and all five KCNQ transcripts in the neural retina. At the protein level, KCNQ5 was detected in the RPE, whereas both KCNQ4 and KCNQ5 were found in neural retina. In situ hybridization in frozen monkey retinal sections revealed KCNQ5 gene expression in the ganglion cell layer and the inner and outer nuclear layers of the neural retina, but results in the RPE were inconclusive due to the presence of melanin. Immunohistochemistry revealed KCNQ5 in the inner and outer plexiform layers, in cone and rod photoreceptor inner segments, and near the basal membrane of the RPE. The data suggest that KCNQ5 channels contribute to the RPE basal membrane K+ conductance and, thus, likely play an important role in active K+ absorption. The distribution of KCNQ5 in neural retina suggests that these channels may function in the shaping of the photoresponses of cone and rod photoreceptors and the processing of visual information by retinal neurons.

scholarly journals Direct regulation of nacre, a zebrafish MITF homolog required for pigment cell formation, by the Wnt pathway

2000 ◽  
Vol 14 (2) ◽  
pp. 158-162 ◽  
Author(s):  
Richard I. Dorsky ◽  
David W. Raible ◽  
Randall T. Moon
Keyword(s):  
Cell Differentiation ◽  
Binding Sites ◽  
Pigment Cell ◽  
Cell Formation ◽  
Dominant Negative ◽  
Reporter Construct ◽  
Cell Fates ◽  
Necessary And Sufficient

We have shown that Wnt signals are necessary and sufficient for neural crest cells to adopt pigment cell fates. nacre, a zebrafish homolog of MITF, is required for pigment cell differentiation. We isolated a promoter region of nacre that contains Tcf/Lef binding sites, which can mediate Wnt responsiveness. This promoter binds to zebrafish Lef1 protein in vitro, and a nacre reporter construct is strongly repressed by dominant-negative Tcf in melanoma cells. Mutation of Tcf/Lef sites abolishes Lef1 binding and reporter function in vivo. Wnt signaling therefore directly activatesnacre, which in turn leads to pigment cell differentiation.

scholarly journals Robust and Scalable Angiogenesis Assay of Perfused 3D Human iPSC-Derived Endothelium for Anti-Angiogenic Drug Screening

2020 ◽  
Vol 21 (13) ◽  
pp. 4804
Author(s):  
Vincent van Duinen ◽  
Wendy Stam ◽  
Eva Mulder ◽  
Farbod Famili ◽  
Arie Reijerkerk ◽  
...  
Keyword(s):  
Drug Screening ◽  
Cell Formation ◽  
Cell Types ◽  
Culture Conditions ◽  
In Vitro Assays ◽  
Vegf Receptor ◽  
Screening Assay ◽  
Angiogenesis Assay

To advance pre-clinical vascular drug research, in vitro assays are needed that closely mimic the process of angiogenesis in vivo. Such assays should combine physiological relevant culture conditions with robustness and scalability to enable drug screening. We developed a perfused 3D angiogenesis assay that includes endothelial cells (ECs) from induced pluripotent stem cells (iPSC) and assessed its performance and suitability for anti-angiogenic drug screening. Angiogenic sprouting was compared with primary ECs and showed that the microvessels from iPSC-EC exhibit similar sprouting behavior, including tip cell formation, directional sprouting and lumen formation. Inhibition with sunitinib, a clinically used vascular endothelial growth factor (VEGF) receptor type 2 inhibitor, and 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO), a transient glycolysis inhibitor, both significantly reduced the sprouting of both iPSC-ECs and primary ECs, supporting that both cell types show VEGF gradient-driven angiogenic sprouting. The assay performance was quantified for sunitinib, yielding a minimal signal window of 11 and Z-factor of at least 0.75, both meeting the criteria to be used as screening assay. In conclusion, we have developed a robust and scalable assay that includes physiological relevant culture conditions and is amenable to screening of anti-angiogenic compounds.

Phenotypic plasticity in the intercalated cell: the hensin pathway

1998 ◽  
Vol 275 (2) ◽  
pp. F183-F190 ◽  
Author(s):  
Qais Al-Awqati ◽  
S. Vijayakumar ◽  
C. Hikita ◽  
J. Chen ◽  
J. Takito
Keyword(s):  
Collecting Duct ◽  
Basolateral Membrane ◽  
Cell Types ◽  
Band 3 ◽  
Cytoskeletal Proteins ◽  
Β Cell ◽  
Biochemical Basis ◽  
Intercalated Cell ◽  
Immortalized Cell

The collecting duct of the renal tubule contains two cell types, one of which, the intercalated cell, is responsible for acidification and alkalinization of urine. These cells exist in a multiplicity of morphological forms, with two extreme types, α and β. The former acidifies the urine by an apical proton-translocating ATPase and a basolateral Cl/HCO3 exchanger, which is an alternately spliced form of band 3. This kidney form of band 3, kAE1, is present in the apical membrane of the β-cell, which has the H+-ATPase on the basolateral membrane. We had suggested previously that metabolic acidosis leads to conversion of β-types to α-types. To study the biochemical basis of this plasticity, we used an immortalized cell line of the β-cell and showed that these cells convert to the α-phenotype when plated at superconfluent density. At high density these cells localize a new protein, which we term “hensin,” to the extracellular matrix, and hensin acts as a molecular switch capable of changing the phenotype of these cells in vitro. Hensin induces new cytoskeletal proteins, makes the cells assume a more columnar shape and retargets kAE1 and the H+-ATPase. These recent studies suggest that the conversion of β- to α-cells, at least in vitro, bears many of the hallmarks of terminal differentiation.

scholarly journals Adipose-tissue derived signals control bone remodelling

2020 ◽  
Author(s):  
Maria-Bernadette Madel ◽  
He Fu ◽  
Dominique D. Pierroz ◽  
Mariano Schiffrin ◽  
Carine Winkler ◽  
...  
Keyword(s):  
Bone Erosion ◽  
Cell Formation ◽  
Cell Types ◽  
Whole Body ◽  
Long Bone ◽  
Bone Homeostasis ◽  
Multiple Cell ◽  
The One

SummaryLong bones from mammals host blood cell formation and contain multiple cell types, including adipocytes. Physiological functions of bone marrow adipocytes are poorly documented. Herein, we used adipocyte-deficient PPARγ-whole body null mice to investigate the consequence of total adipocyte deficiency on bone homeostasis in mice. We first highlight the dual bone phenotype of PPARγ null mice: on the one hand the increase bone formation and subsequent trabecularization extending in the long bone diaphysis, due to the well-known impact of PPARγ deficiency on osteoblasts formation and activity; on the other hand, an increased osteoclastogenesis in the cortical bone. We then further explore the cause of this unexpected increased osteoclastogenesis using two independent models of lipoatrophy, which recapitulated this phenotype. This demonstrates that hyperosteoclastogenesis is not intrinsically linked to PPARγ deficiency, but is a consequence of the total lipodystrophy. We further showed that adiponectin, a cytokine produced by adipocytes and mesenchymal stromal cells is a potent inhibitor of osteoclastogenesis in vitro and in vivo. Moreover, pharmacological activation of adiponectin receptors by the synthetic agonist AdipoRon inhibits mature osteoclast activity both in mouse and human cells by blocking podosome formation through AMPK activation. Finally, we demonstrated that AdipoRon treatment blocks bone erosion in vivo in a murine model of inflammatory bone loss, providing potential new approaches to treat osteoporosis.

scholarly journals Neural retina limits the nonviral gene transfer to retinal pigment epithelium in an in vitro bovine eye model

2004 ◽  
Vol 6 (3) ◽  
pp. 72-80 ◽  
Author(s):  
Leena Pitkänen ◽  
Jukka Pelkonen ◽  
Marika Ruponen ◽  
Seppo Rönkkö ◽  
Arto Urtti
Keyword(s):  
Retinal Pigment Epithelium ◽  
Gene Transfer ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Neural Retina ◽  
Nonviral Gene Transfer ◽  
Eye Model

scholarly journals Propofol impairs specification of retinal cell types in zebrafish by inhibiting Zisp-mediated Noggin-1 palmitoylation and trafficking

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoqing Fan ◽  
Haoran Yang ◽  
Lizhu Hu ◽  
Delong Wang ◽  
Ruiting Wang ◽  
...  
Keyword(s):  
Neuronal Development ◽  
Cell Formation ◽  
Cognitive Disorders ◽  
Cell Types ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Retinal Cell ◽  
Soluble Form ◽  
In Vivo Experiments

Abstract Background Propofol can have adverse effects on developing neurons, leading to cognitive disorders, but the mechanism of such an effect remains elusive. Here, we aimed to investigate the effect of propofol on neuronal development in zebrafish and to identify the molecular mechanism(s) involved in this pathway. Methods The effect of propofol on neuronal development was demonstrated by a series of in vitro and in vivo experiments. mRNA injections, whole-mount in situ hybridization and immunohistochemistry, quantitative real-time polymerase chain reaction, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, 5-ethynyl-2′-deoxyuridine labeling, co-immunoprecipitation, and acyl–biotin exchange labeling were used to identify the potential mechanisms of propofol-mediated zisp expression and determine its effect on the specification of retinal cell types. Results Propofol impaired the specification of retinal cell types, thereby inhibiting neuronal and glial cell formation in retinas, mainly through the inhibition of Zisp expression. Furthermore, Zisp promoted the stabilization and secretion of a soluble form of the membrane-associated protein Noggin-1, a specific palmitoylation substrate. Conclusions Propofol caused a severe phenotype during neuronal development in zebrafish. Our findings established a direct link between an anesthetic agent and protein palmitoylation in the regulation of neuronal development. This could be used to investigate the mechanisms via which the improper use of propofol might result in neuronal defects.

scholarly journals Macromere cell fates during sea urchin development

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1085-1091 ◽  
Author(s):  
R.A. Cameron ◽  
S.E. Fraser ◽  
R.J. Britten ◽  
E.H. Davidson
Keyword(s):  
Sea Urchin ◽  
Pigment Cell ◽  
Cell Lineage ◽  
Cell Types ◽  
Cellular Migration ◽  
The Other ◽  
Pigment Cells ◽  
Basal Cells ◽  
Cell Fates ◽  
Gut Pigment

This paper examines the cell lineage relationships and cell fates in embryos of the sea urchin Strongylocentrotus purpuratus leading to the various cell types derived from the definitive vegetal plate territory or the veg2 tier of cells. These cell types are gut, pigment cells, basal cells and coelomic pouches. They are cell types that constitute embryonic structures through cellular migration or rearrangement unlike the relatively non-motile ectoderm cell types. For this analysis, we use previous knowledge of lineage to assign macromeres to one of four types: VOM, the oral macromere; VAM, the aboral macromere, right and left VLM, the lateral macromeres. Each of the four macromeres contributes progeny to all of the cell types that descend from the definitive vegetal plate. Thus in the gut each macromere contributes to the esophagus, stomach and intestine, and the stripe of labeled cells descendant from a macromere reflects the re-arrangement of cells that occurs during archenteron elongation. Pigment cell contributions exhibit no consistent pattern among the four macromeres, and are haphazardly distributed throughout the ectoderm. Gut and pigment cell contributions are thus radially symmetrical. In contrast, the VOM blastomere contributes to both of the coelomic pouches while the other three macromeres contribute to only one or the other pouch. The total of the macromere contribution amounts to 60% of the cells constituting the coelomic pouches.

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