Showing papers on "Transdifferentiation published in 1995"
TL;DR: The results demonstrate that a developmental switch between these two related but highly specialized cell types can be controlled by the expression of key adipogenic transcription factors.
Abstract: Skeletal muscle and adipose tissue development often has a reciprocal relationship in vivo, particularly in myodystrophic states. We have investigated whether determined myoblasts with no inherent adipogenic potential can be induced to transdifferentiate into mature adipocytes by the ectopic expression of two adipogenic transcription factors, PPAR gamma and C/EBP alpha. When cultured under optimal conditions for muscle differentiation, murine G8 myoblasts expressing PPAR gamma and C/EBP alpha show markedly reduced levels of the myogenic basic helix-loop-helix proteins MyoD, myogenin, MRF4, and myf5 and are completely unable to differentiate into myotubes. Under conditions permissive for adipogenesis including a PPAR activator, these cells differentiate into mature adipocytes that express molecular markers characteristic of this lineage. Our results demonstrate that a developmental switch between these two related but highly specialized cell types can be controlled by the expression of key adipogenic transcription factors. These factors have an ability to inhibit myogenesis that is temporally and functionally separate from their ability to stimulate adipogenesis.
652 citations
Journal Article•
TL;DR: Results indicate that RPE transdifferentiate in culture and that this transition is accompanied by a shift in biologic activities, which indicates morphologic and behavioral transdifferentiation of these cells in culture are influencing factors in experimental pathology.
Abstract: PURPOSE To describe and evaluate retinal pigment epithelial (RPE) cell transdifferentiation in vitro and to determine its importance to the development of proliferative vitreoretinal disorders. METHODS Porcine RPE cells from single animals were examined at different passages in culture. The authors examined cellular morphology, contraction of a collagenous matrix, and adhesion to fibronectin and type I collagen-coated substrata. These activities were correlated with loss of epithelial characteristics, redistribution of the actin cytoskeleton, and expression of alpha-smooth muscle actin (alpha-SMA), a marker of myoid differentiation. RESULTS During routine culture on tissue culture plastic, porcine RPE cells lose epithelial characteristics and acquire a mesenchymal cell-like phenotype. The ability of cultured porcine RPE cells to adhere to and exert tractional forces on an extracellular matrix increases with continued passage in vitro and transdifferentiation. This correlates with the loss of the differentiated epithelial morphology, decreased expression of the epithelial marker cytokeratin 18, redistribution of the actin cytoskeleton, and de novo expression of alpha-SMA. CONCLUSION Results indicate that RPE transdifferentiate in culture and that this transition is accompanied by a shift in biologic activities. Therefore, morphologic and behavioral transdifferentiation of these cells in culture are influencing factors in experimental pathology. The potential relevance of these extensive changes to the biology of proliferative vitreoretinal disorders is discussed.
238 citations
TL;DR: It is concluded that commitment to the AT1 and AT2 cell lineages requires continuous regulatory input to maintain the differentiated states, and that transdifferentiation between AT2 and AT1 cells may be reversible.
Abstract: Alveolar epithelial type II (AT2) cells have been thought to be the progenitors of terminally differentiated type I (AT1) cells in the adult animal in vivo. In this study, we used an AT1 cell-specific monoclonal antibody (mAb VIII B2) to investigate expression of the AT1 cell phenotype accompanying reversible changes in expression of the AT2 cell phenotype. AT2 cells were isolated and cultured either on attached collagen gels or on gels detached 1 or 4 days after plating and maintained thereafter as floating gels. Monolayers on both attached and floating gels were harvested on days 4 and 8 and analyzed by electron microscopy for changes in morphology and binding of mAb VIII B2. Results indicate that: (1) alveolar epithelial cells (AEC) on attached gels develop characteristics of the AT1 cell phenotype, (2) AEC on gels detached on day 1 maintain features of the AT2 cell phenotype (and do not react with mAb VIII B2), and (3) the expression of AT1 cell phenotypic traits seen by day 4 on attached gels is reversed after detachment. We conclude that commitment to the AT1 and AT2 cell lineages requires continuous regulatory input to maintain the differentiated states, and that transdifferentiation between AT2 and AT1 cells may be reversible.
184 citations
TL;DR: The musculature of the mouse esophagus was found to undergo a conversion from smooth muscle in the fetus to skeletal muscle during early postnatal development, which suggests that this conversion is a result of programmed transdifferentiation.
Abstract: Transdifferentiation is a relatively rare phenomenon in which cells of one differentiated type and function switch to a second discrete identity. In vertebrate embryos, smooth muscle and skeletal muscle are distinct tissues that arise from separate compartments of the mesoderm. The musculature of the mouse esophagus was found to undergo a conversion from smooth muscle in the fetus to skeletal muscle during early postnatal development. The switch from smooth to skeletal muscle features the transitory appearance of individual cells expressing a mixed phenotype, which suggests that this conversion is a result of programmed transdifferentiation.
161 citations
TL;DR: It is believed that the pancreas retains the ability to regenerate a functioning islet cell mass in the postnatal period, and that the process of cell transformation leading to islet neogenesis is mediated by growth factors that are intrinsic to the gland.
156 citations
TL;DR: It is shown that mammalian RPE possesses the ability to transdifferentiate into neural retina at early embryonic stages, and that already differentiated embryonic rat RPE still retain the able to become neural retina up to certain stage.
146 citations
TL;DR: The differentiated state of specialized cells appears to be dependent on interactions between the extracellular microenvironment, cytoplasmic signals and DNA, and perturbations in these interactions lead to phenotypic alterations of the cell--referred to as transdifferentiation.
58 citations
TL;DR: The method of in-vitro culture of pigmented epithelial cells has been optimized to enable detailed studies of the transdifferentiation process by molecular techniques, and growth factors and extracellular matrix components are found to be important in the control of theTrans differentiation process.
54 citations
TL;DR: Fragments of striated muscle tissue of Anthomedusae can be isolated and cultured and Initiation of DNA replication seems to be correlated with a disturbance of cell-ECM interactions.
45 citations
TL;DR: In the budding tunicate, Polyandrocarpa misakiensis, a bud consists of two epithelial sheets, of which the inner, atrial epithelium shows developmental multipotency, which may be triggered by endogenous retinoids, probably retinoic acid (RA).
45 citations
TL;DR: The neural retina of amphibians and chick embryos regenerates following damage and the molecular mechanisms that control the cell fate decision between these two very different cell types involves soluble growth factors of the fibroblast growth factor family, as well as components of the extracellular matrix.
TL;DR: It is proposed that thyroid C-cells are derived from a vagal sympathoadrenal progenitor, similar to serotonergic enteric neurons, and can undergo neuronal transdifferentiation, and should provide suitable and convenient models for molecular and cellular studies onSerotonergic neurons.
Abstract: We have investigated whether rat thyroid C-cells can acquire a phenotype similar to serotonergic neurons. C-cells are neural crest derived endocrine cells with some intrinsic neuronal and serotonergic properties. A relatively simple isolation scheme yielded cultures of about 50% initial purity, as measured by fluorescence activated cell sorting. These enriched C-cells could extend neurites up to 550 microns on a laminin-containing substratum in the presence of NGF. The cultured C-cells expressed neurofilaments and this expression was enhanced by NGF treatment. The C-cells also expressed two markers of the sympathoadrenal neural crest lineage, the mammalian achaete scute homolog-1 (MASH-1) transcription factor, and the B2 cell surface antigen. Interestingly, MASH-1 was not detectable after the C-cells were placed in culture, which is consistent with neuronal differentiation, since MASH-1 is only expressed in neuronal progenitors prior to differentiation. We then demonstrated that C-cells possess the fundamental features of serotonergic neurons: synthesis and secretion, uptake, and feedback control. The enriched C-cells, as well as the CA77 C-cell line, showed 5-HT immunostaining, expression of tryptophan hydroxylase mRNA, 5-HT1B autoreceptor mRNA, and 5-HT transporter mRNA and activity. NGF greatly induced 5-HT transporter activity as determined by sensitivity to sertraline, a selective 5-HT reuptake inhibitor. Based on these results, we propose that thyroid C-cells are derived from a vagal sympathoadrenal progenitor, similar to serotonergic enteric neurons, and can undergo neuronal transdifferentiation. Hence, these cells should provide suitable and convenient models for molecular and cellular studies on serotonergic neurons.
TL;DR: It is demonstrated that chromaffin cells cografted with NGF-producing fibroblasts undergo transdifferentiation in vivo and express many characteristics of mature sympathetic neurons.
Abstract: Although adrenal medullary chromaffin cells have been used extensively for intracerebral grafting, their survival has generally been poor. Improved survival of the implanted cells has been achieved by exposing the chromaffin cells to NGF in vivo. Culture studies have shown, however, that chromaffin cells are converted into sympathetic neurons when NGF is included in the medium. The degree to which such a transdifferentiation may occur in vivo has not been determined. We assessed the effects of cografting chromaffin cells with primary fibroblasts genetically engineered to express NGF. Chromaffin cells from 10 d old rats were implanted with NGF-producing or beta- galactosidase-producing primary fibroblasts (control fibroblasts) into the striatum of 6-hydroxydopamine treated adult rats of the same strain. Eight weeks postgrafting, chromaffin cells cografted with NGF- producing fibroblasts displayed many of the features of mature sympathetic neurons such as large somata, long processes, transmitter vesicles similar to those found in neurons, and positive immunolabeling for the neuronal markers neurofilament, MAP2 and SCG10. Chromaffin- derived neuron number was also significantly enhanced in the presence of NGF-producing fibroblasts. While control fibroblasts were also found to increase chromaffin cell number above that of chromaffin cells grafted alone, the control fibroblasts did not induce neuronal transdifferentiation. These results demonstrate that chromaffin cells cografted with NGF-producing fibroblasts undergo transdifferentiation in vivo and express many characteristics of mature sympathetic neurons. The consequences of this transdifferentiation on the long term survival and function of the transplanted cells in vivo remain to be clarified.
TL;DR: Evidence is presented that certain cell types of the limb have the capacity to differentiate to different cell types than their original one by cellular metaplasia, called transdifferentiation.
TL;DR: The skeletal muscle tropomyosin 3' UTR induces transdifferentiation into a striated muscle phenotype in a cell-type-specific context and organizes muscle and nonmuscle isoforms into the same structures.
Abstract: Transfection with a plasmid encoding the 3' untranslated region (3' UTR) of skeletal muscle tropomyosin induces chicken embryonic fibroblasts to express skeletal tropomyosin. Such cells become spindle shaped, fuse, and express titin, a marker of striated muscle differentiation. Skeletal muscle tropomyosin and titin organize in sarcomeric arrays. When the tropomyosin 3' UTR is expressed in osteoblasts, less skeletal muscle tropomyosin is expressed, and titin expression is delayed. Some transfected osteoblasts become spindle shaped but do not fuse nor organize these proteins into sarcomeres. Transfected cells expressing muscle tropomyosin organize muscle and nonmuscle isoforms into the same structures. Thus, the skeletal muscle tropomyosin 3' UTR induces transdifferentiation into a striated muscle phenotype in a cell-type-specific context.
TL;DR: The data suggest the involvement of DNA-repair events in the transdifferentiation of mesophyll cells into tracheary elements in Zinnia elegans.
Abstract: In cultures of isolated mesophyll cells ofZinnia elegans, transdifferentiation into tracheary elements is induced by a combination of auxin and cytokinin and is blocked by inhibitors of DNA synthesis and poly (ADP-ribose) synthesis. During transdifferentiation, a very low level of synthesis of nuclear DNA was found in some cultured cells by microautoradiography after pulse-labeling with [3H]thymidine. Density profiles of nuclear DNA that had been double-labeledin vivo with bromodeoxyuridine (BrdU) and [3H]thymidine indicated that this DNA synthesis was repair-type synthesis. The sedimentation velocity of nucleoids increased during the culture of isolated mesophyll cells and the increase was dependent on phytohormones. This phenomenon may reflect the rejoining of DNA strand breaks after repair-type DNA synthesis during transdifferentiation. Treatment of cells with inhibitors of DNA synthesis or of poly(ADP-ribose) synthesis prevented the increase in the sedimentation velocity of nucleoids. The data suggest the involvement of DNA-repair events in the transdifferentiation of mesophyll cells into tracheary elements.
TL;DR: Results indicate that localized sources of growth factors are effective in inducing the transdifferentiation of grafted Chromaffin cells as well as the extension of chromaffin-derived neurites into the host parenchyma, and caution that promoting trans Differentiation and neurite extension from engrafted chromAffin cells may not be sufficient to achieve desired functional effects of such grafts.
TL;DR: Based on heterokaryon and 5-aza-cytidine-induced hypomethylation experiments, the muscle determination gene MyoD1 was identified and isolated, which was shown to induce myogenic differentiation even in cells of ectodermal lineage.
Journal Article•
TL;DR: The immunostaining of keratins was absent in the cells of normal and regenerating retina, as well as in retinal pigment epithelium cells before restoration of their structural and functional relationship with the retinal regenerate.
Abstract: Keratins of the cytoskeletal intermediate filaments have been identified immunohistochemically in pigment epithelium cells of the adult newt retina. We studied the expression of keratins in transdifferentiating and redifferentiating cells of the retinal pigment epithelium at different periods after removal of the retina. We have shown that the expression of keratins decreases. This appears as the decreased intensity of the immunospecific reaction soon after the operation. The latter observation has also been made immediately after artificial dissociation of the pigment epithelium cells of the retina isolated from nonoperated newt eyes. We found that the immunostaining of keratins was absent in the cells of normal and regenerating retina, as well as in retinal pigment epithelium cells before restoration of their structural and functional relationship with the retinal regenerate. The results obtained provide evidence for the inhibition of keratins expression during the transformation of retinal pigment epithelium into the retina. We proposed that there exists a mechanism responsible for gradual replacement of keratins by proteins of neurofilaments that have earlier been identified at the beginning of transdifferentiation of the retinal pigment epithelium.
TL;DR: Results have shown that in P. misakiensis the cell division cycle, probably DNA replication, is indispensable for transdifferentiation of the atrial epithelium, although every cell in the organ rudiment need not enter cell cycling, and suggest that homoiogenetic induction occurs between dividing cells and non‐dividing cells.
Abstract: In the tunicate, Polyandrocarpa misakiensis, transdifferentiation occurs in the multipotent atrial epithelium during morphallactic bud development. Irradiation (10–80 Gy) or aphidicolin (10 μg/mL) blocked this process severely, although the atrial epithelium could form organ placodes. The placodes consisted of cuboidal cells with a high nucleus : cytoplasm ratio and were lacking the alkaline phosphatase antigen from the cell surface, suggesting that the atrial epithelium might undergo dedifferentiation without initiating cell cycling. Irradiated buds could resume organogenesis in temporal accordance with the restoration of mitotic activity. Bud pieces irradiated at 40 Gy were juxtaposed with unirradiated counterparts. In the operated buds, irradiated, non-dividing cells participated in organogenesis at the site of juxtaposition in cooperation with the unirradiated, dividing cells. These results have shown that in P. misakiensis the cell division cycle, probably DNA replication, is indispensable for transdifferentiation of the atrial epithelium, although every cell in the organ rudiment need not enter cell cycling. We suggest that homoiogenetic induction occurs between dividing cells and non-dividing cells.
01 Jan 1995
TL;DR: Using Pod-EPPT as a molecular marker for head quality the morphological relationship between the two metagenic life stages of this hydroid, the polyp and the medusa, was studied and demonstrated that expression of the gene corresponding is restricted to secretory cells in the endoderm of the oral hypostome region of polyps and medusae and, presumably, to progenitor cells of this type.
Abstract: An antiserum to transdifferentiated striated muscle cells from the medusa of Podocoryne carnea was prepared and used to screen a λ gt11-expression library prepared from gonozoids of P. carnea. We isolated a cDNA clone termed Pod-EPPT with at least 63 tandem repeats of the tetrapeptide-motive glu-pro-pro-thr, named Pod-EPPT. Using Pod-EPPT as a molecular marker for head quality the morphological relationship between the two metagenic life stages of this hydroid, the polyp and the medusa, was studied. In situ hybridization demonstrated that expression of the gene corresponding is restricted to secretory cells in the endoderm of the oral hypostome region of polyps and medusae and, presumably, to progenitor cells of this type. Cells expressing Pod-EPPT could not be observed in the larval stage. During head regeneration in polyps, Pod-EPPT expression is upregulated soon after head removal in previously non-expressing cells and in newly differentiating secretory cells. This activation of a head-specific gene precedes the morphologically obvious events of head regeneration. Pod-EPPT is one of the genes that are activated during manubrium (mouth) regeneration from experimentally combined subumbrellar plate endoderm and striated muscle of the medusa.
Journal Article•
TL;DR: The present results indicate that human monocytes from the peripheral blood are capable of transforming into fibroblast-like cells under in vitro conditions, and blood-borne monocytes could represent a major source for the fibro Blast cells found in proliferative vitreoretinopathy.
Abstract: Proliferative vitreoretinopathy is a process of uncontrolled cell proliferation in the vitreous. There is some evidence that monocytes and macrophages play an essential role during the pathogenesis. The purpose of this study was to investigate whether human monocytes derived from the peripheral blood can transform into fibroblast-like cells under in vitro conditions. To provide similar environmental conditions in vitro, human monocytes were brought onto fresh calf vitreous and kept for 17 days. Monocytes differentiated into macrophages and assumed a fibroblast-like morphology. During transdifferentiation, expression of CD11c was present for only 3 days and that of CD18, for only 7 days. The longest presence was found for CD68 expression, which lasted for 15 days. The present results indicate that human monocytes from the peripheral blood are capable of transforming into fibroblast-like cells under in vitro conditions. Blood-borne monocytes could therefore represent a major source for the fibroblast-like cells found in proliferative vitreoretinopathy.