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Results for “CELL DIFFERENTIATION”

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At least 55 records · Page 3Linked to original sources
PubMed1995

Factors controlling prespore cell differentiation in Dictyostelium discoideum: minute amounts of differentiation-inducing factor promote prespore cell differentiation.

Amoebae of strain V12M2 differentiate efficiently into prespore cells without cell contact in a salt solution containing cAMP, if the pH of the medium is maintained suitably acidic using a restricted buffer [31]. Under such conditions, most cells differentiate into prespore cells at pH 5.2. Using this developmental system, the elements controlling prespore-cell differentiation were analyzed. First, the dependence on cell density was examined. At a very low density (10(2) cells/cm2), most cells did not differentiate. As the density was increased the proportion of prespore cells differentiating increased, reaching a maximum at 5 x 10(3) cells/cm2. Conditioned medium could mimic the effects of cell density on cell differentiation. These findings suggest the presence of factor(s) released into the medium which are involved in inducing prespore-cell differentiation. The conditioned medium was found to contain at least two prespore-inducing components; one is a novel factor(s) and the other is DIF, which has previous only been considered to repress prespore-cell differentiation. These findings were supported by experiments using a DIF-deficient mutant, HM44.

Animals↗
PubMed1986

Cell differentiation and cell cycle effects on human promyelocytic leukemia cells induced by 12-O-tetradecanoylphorbol-13-acetate.

As has been reported, doses of 12-O-tetradecanoylphorbol-13-acetate (TPA) as small as 1 to 100 ng/ml induced human promyelocytic leukemia HL-60 cells to differentiate terminally into macrophage-like cells rather than toward cells of the granulocytic series. This differentiation was accompanied by the appearance of monocyte/macrophage markers and by the disappearance of myeloid markers from the view point of enzyme cytochemistry. Contrasted to untreated HL-60 cells, TPA-treated cells increased in cell size and showed increased phagocytotic activities against opsonized sheep blood red cells and activated yeast. Nitroblue tetrazolium-positive cells increased rapidly after TPA exposure. The alterations of the cell cycle traverse of HL-60 cells by TPA were analyzed by [3H]thymidine autoradiography, flow microfluorimetry, and mitotic cell counting. TPA sequentially caused (a) inhibition of cells to move from G1 to S near G1/S boundary in G1; (b) temporary inhibition in G2; (c) growth arrest of most cells in G1 within 2 to 3 days after TPA exposure.

Cell Cycle↗
PubMed2005

Temporal changes in NCAM immunoreactivity during taste cell differentiation and cell lineage relationships in taste buds.

Neural cell adhesion molecule (NCAM) is a type III cell marker in the taste buds. In order to clarify the cell type of Mash1-expressing cells in taste buds, expression of NCAM was examined in Mash1-expressing taste cells of adult mice in comparison with gustducin- and T1r3-expressing cells, using a combination of NCAM immunohistochemistry and in situ hybridization. About 98% of Mash1-expressing cells were NCAM immunopositive (IP), suggesting that Mash1-expressing cells should be categorized as type III cells. Unexpectedly, small subsets of gustducin- and T1r3-expressing cells were also found to be NCAM-IP, contradicting previous immunohistochemical studies in rats, in which gustducin-IP cells were observed specifically in type II cells, which do not have NCAM immunoreactivity. Examinations of developing taste buds showed temporal changes in the ratio of NCAM-IP cells in gustducin- and T1r3-expressing cells; the ratio of NCAM-IP cells in these gene-expressing cells were approximately 90% at 0.5 days after birth and decreased markedly during development. In contrast, the majority of Mash1-expressing cells showed constant NCAM immunoreactivity throughout development. In addition, BrdU-labeling experiments showed that the differentiation of Mash1-expressing cells precedes those of gustducin- and T1r3-expressing cells in taste buds of adult mice. These results suggest that T1r3- and gustducin-expressing cells are NCAM-IP at the beginning of cell differentiation, and that NCAM immunoreactivity in gustducin- and T1r3-expressing cells might remain from the previous developmental stage expressing Mash1.

Animals↗
PubMed1985

Control of cell differentiation during proliferation. II. Myeloid differentiation and cell cycle arrest of HL-60 promyelocytes preceded by nuclear structural changes.

The time-dependent dynamics of nuclear structure, cell cycle transit and arrest, and cellular differentiation were studied using the human promyelocytic leukemia cell line HL-60. Myeloid differentiation of HL-60 cells was induced by 10(-6) M beta, all trans, retinoic acid (RA). During exponential growth the cells had G1, S, G2 and M durations of 9, 11, 0.5 and 0.5 h respectively. Significant growth arrest in the G1/0 phase of the cell cycle was apparent after 48 h of RA exposure or after two division cycles. Thereafter, cells arrested in G1/0 with wide dispersion in times of arrest which extended over several cell cycle generation times. The kinetics of phenotypic differentiation, detected by phorbol myristate acetate inducible superoxide production, paralleled those of G1/0 growth arrest with similar lag and dispersion. These kinetics are consistent with a model hypothesizing the existence of an S-phase differentiation control (DC) point regulating both terminal proliferation and differentiation. Before any cell differentiation or termination of cell proliferation occurred, the nuclei of RA-treated cells underwent a structural change detected by narrow-angle light scatter measured with flow cytometry. Narrow-angle light scatter was transiently reduced, reaching a nadir at 24-48 h and returning to control values at 96 h. This change was independent of cell cycle phase or total nuclear protein content. It was associated with a morphological change of the nuclear membrane from a smooth to dimpled or pitted structure. These findings focus attention on the potential significance of nuclear structural reorganization as an early event during cell differentiation.

Cell Cycle↗
PubMed2002

The pore of the leaf cavity of Azolla species: teat cell differentiation and cell wall projections.

The differentiation of the specialized secretory teat cells of the leaf cavity pore of Azolla species was investigated at the ultrastructural level with emphasis on their peculiar cell wall projections. The results indicated that the projections are formed as soon as the teat cells complete their differentiation and that their production is principally associated with changes in endoplasmic reticulum profiles. The number of projections increases with the teat cell age and is stimulated under salt and P deficiency stresses. Salt stress also promotes their emergence on Azolla species that under normal conditions do not produce projections. Cytochemical tests on different Azolla species showed that the projection composition is almost identical: proteins, acidic polysaccharides, and pectin are always detected. This study revealed that Azolla teat cell projections differ fundamentally from other types of hitherto described cell wall projections that are considered as remnant structures from cell separation. In contrast, in Azolla teat cells projections are actively produced and compounds are excreted by an exocytotic mechanism. The possible role of the projections in the symbiosis of Azolla spp. with Anabaena azollae is discussed.

Cell Differentiation↗
PubMed1988

Production and utilization of growth factors related to fibroblast growth factor by embryonal carcinoma cells and their differentiated cells.

Previous studies have established that embryonal carcinoma (EC) cells produce several different growth factors, but express few, if any, receptors for epidermal growth factor, platelet-derived growth factor, or transforming growth factor type-beta. In this study, the production and utilization of fibroblast growth factor (FGF) by EC cells and their differentiated cells were investigated. We have determined that EC cells produce a heat-labile, heparin-binding factor that competes with FGF for binding to membrane receptors and appears to be immunologically related to FGF. The same or a similar factor is produced by three different EC cell lines, including a multipotent human EC cell line. However, production of this factor is apparently reduced when each EC cell line differentiates. Unlike the parental EC cells, the differentiated cells respond to FGF by growth stimulation and the growth responses to FGF correlate with increased binding of FGF. Although the binding data indicate that both the EC cells and their differentiated cells exhibit high affinity receptors for FGF, the differentiated cells express these receptors at levels approximately 10-fold higher. These findings suggest that the FGF-related growth factor could influence the growth of EC cells or their differentiated cells.

Binding, Competitive↗
PubMed1984

Post-transcriptional regulation of the abundance of mRNAs encoding alpha-tubulin and a 94,000-dalton protein in teratocarcinoma-derived stem cells versus differentiated cells.

Changes in the expression of the genes encoding alpha-tubulin and a 94,000-dalton protein (p94) specified by a cDNA clone, p4-30, were examined in a differentiated teratocarcinoma-derived parietal endoderm cell line, PYS-2, and an undifferentiated teratocarcinoma stem cell line, F9. Relative to other proteins or mRNA species, the synthesis rate of the alpha-tubulins and of p94, as well as the levels of their corresponding cytoplasmic mRNAs, were lower in PYS-2 than in F9 cells. The decrease was greater for the relative abundance of cytoplasmic alpha-tubulin mRNA than for p94 mRNA. Similarly, induction of differentiation of F9 cells by simultaneous exposure to retinoic acid (RA) and dibutyryl cyclic AMP resulted in reduced relative levels of the cytoplasmic mRNAs for these proteins. The reduction in abundance of the two RNA species was not due to a decrease in growth rate since the differentiated cells, PYS-2, RA-treated F9, and RA plus dibutyryl cyclic AMP-treated F9 cells, grew at a rate similar to that of undifferentiated F9 cells. However, induction of differentiation of F9 cells by treatment with RA alone did not cause down-regulation of the two RNA species. The relative levels of total cellular RNA encoding alpha-tubulin and p94 in PYS-2 cells were also lower than those in F9 cells to an extent comparable to the decrease in the cytoplasmic RNAs. Since the apparent relative rates of RNA transcription were similar in both cell types, we conclude that the reduction in relative levels of the alpha-tubulin and p94 RNAs in the cell depends largely on the relative stability of the two RNAs and not on the relative rates of transcription. The faster disappearance of the two RNA species relative to other cellular RNAs from actinomycin D-treated PYS-2 compared with F9 cells is consistent with this interpretation.

Animals↗