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Modulation of fibronectin, laminin, and cellular adhesion in the transformation and differentiation of murine AKR fibroblasts (1987)

Chakrabarty, Subhas ; Brattain, Michael G. ; Ochs, Robert L. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 133 (1987), S. 415-425

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: The functional relationship between membrane/cell surface expression of fibronectin and laminin and transformation/differentiation was examined in an AKR mouse fibroblastic cell model. This model consisted of the untransformed AKR-2B cells, their chemically transformed counterpart (AKR-MCA cells) and the chemically differentiated from of the AKR-MCA cells. The transformed AKR-MCA cells were found to express more surface laminin and less fibronectin than the untransformed AKR-2B cells. The transformed AKR-MCA cells were slower to attach and spread on both plastic and type IV collagen-coated dishes in comparison of the AKR-2B cells. However, a higher percentage of the AKR-MCA cells ultimately attached and spread on the type IV collagen-coated dishes. The induction of differentiation in the AKR-MCA cells by N, N-dimethylformamide (DMF) restored fibronection to the surface of the AKR-MCA cells but reduced laminin expression only slightly. The DMF-treated AKR-MCA cells resembled the AKR-2B cells in that they rapidly attached and spread on plastic dishes and dishes coated with type IV collagen. They also resembled the AKR- MCA cells in that a high proportion ultimately attached and spread on the collagen-coated dishes.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041330302

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Growth modulation by epidermal growth factor (EGF) in human colonic carcinoma cells: Constitutive expression of the human EGF gene (1991)

Huang, Shuang ; Lin, Pin-Fang ; Fan, Dominic ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 148 (1991), S. 220-227

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: The functional role of epidermal growth factor (EGF) in epithelium-derived human colonic carcinoma cells was investigated by transfection with plasmid pUCDS3, which contained synthetic human EGF encoding sequences, into two human colonic carcinoma cell types with dissimilar phenotypic properties: the moderately differentiated and growth factor-responsive Moser and the highly metastatic KM12SM cells. The Moser cells exhibited a proliferative response to treatment with exogenous EGF, while the KM12SM cells did not. The constitutive expression of the human EGF gene in these colonic carcinoma cell types resulted in elevated expression of EGF mRNA, with concurrent production and secretion of a large amount of EGF, and downmodulation of transforming growth factor-alpha (TGF-alpha) secretion. Growth stimulation and down-modulation of both high and low affinity EGF receptors were observed in the EGF-transfected Moser clones. Results of experiments using anti-EGF and anti-EGF-receptor antibody to block the proliferation of EGF-transfected Moser clones suggested that autocrine stimulatory mechanisms involving both EGF and TGF-alpha were operative in these cells. By comparison, a growth-inhibitory effect, with no apparent EGF receptor modulation, was observed in the EGF-transfected KM12SM clones. Both the parental and EGF-transfected KM12SM clones possessed fewer EGF receptors than the Moser cells, and anti-EGF or anti-EGF-receptor antibody did not affect the cells' growth properties. These results suggested that the mechanisms of growth inhibition in the EGF-transfected KM12SM clones were non-autocrine or intracellular in nature. Thus, constitutive expression of the human EGF gene in two phenotypically different, epithelium-derived human colonic carcinoma cells resulted in divergent altered growth characteristics.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041480206

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Modulation of fibronectin synthesis and fibronectin binding during transformation and differentiation of mouse AKR fibroblasts (1990)

Varani, James ; Chakrabarty, Subhas

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 143 (1990), S. 445-454

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: In previous studies it was shown that transformation of AKR fibroblasts with 3-methylcholanthrene was associated with a loss of surface fibronectin and that induction of differentiation of the transformed cells with N,N-dimethylformamide (DMF) was associated with reacquisition of surface fibronectin (Chakrabarty et al., J. Cell. Physiol. 133:415, 1987). It is shown in the present study that changes in surface fibronectin reflect altered fibronectin synthesis and altered fibronectin binding. Both the nontransformed cells (AKR-2B) and their transformed counterparts (AKR-MCA) bound 125I-fibronectin in a receptor-like fashion, but the AKR-MCA cells had only 20% of the receptors found on the AKR-2B cells. Whole cell extracts prepared from the AKR-2B cells and separated by sodium dodecyl sufate-polyacrylamide gel electrophoresis under reducing conditions were examined for 125I-fibronectin binding. Under these conditions, the majority of binding occurred to moieties with molecular weights of 180 kD, 150 kD, and 97 kD. Binding to similar moieties on the AKR-MCA cells was virtually absent but occurred rapidly after treatment with DMF. The appearance of these moieties paralleled the acquisition of 125I-fibronectin binding activity by whole cells. Antibodies to the fibronectin receptor isolated from human placenta reacted with the DMF-sensitive moieties in immunoblot assays. Both the appearance of the fibronectin binding moieties and the acquisition of 125I-fibronectin binding activity by whole cells occurred within 6 hr of DMF treatment and increased over the suosequent 4 day period. The time course of these events paralleled closely the time course for induction of fibronectin biosynthesis by DMF. These changes in fibronectin binding and fibronectin production were associated with alterations in cell-substrate adhesion. The AKR-2B cells rapidly attached and spread on bovine serum albumin-coated dishes and on fibronectin-coated dishes, whereas the AKR-MCA cells were less adhesive on both substrates. Capacity to attach and spread was regained concomitantly with the induction of fibronectin binding and fibronectin production. Adhesion on both substrates was partially inhibited by antibodies to the fibronectin receptor and by RGDS. These studies suggest that fibronectin production and fibronectin binding are coregulated in AKR fibroblasts and that they function together to bring about changes in cell-substrate adhesion.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041430307

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Control of AKR fibroblast phenotype by fibronectin: Regulation of cell-surface fibronectin binding receptor by fibronectin (1994)

Huang, Shuang ; Varani, James ; Chakrabarty, Subhas

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 161 (1994), S. 470-482

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Results of previous studies show that the expression of fibronectin and its cell-surface fibronectin binding receptor is coregulated in 3-methylchloranthrene transformation of normal AKR-2B cells to form AKR-MCA cells and in N, N,-dimethylformamide (DMF) induction of differentiation of transformed AKR-MCA cells (1990, J. Cell. Physiol., 143:445). In this study, we tested the corgulation hypothesis by transfection experiments using an antisense fibronectin expression vector. We determined the effect of antisense fibronectin RNA expression on untransformed AKR-2B cells, and on the responses of transformed AKR-MCA cells to DMF treatment. Expression of antisense fibronectin RNA in AKR-2B cells down-modulated fibronectin production, reduced adhesion to extracellular fibronectin, and altered cellular morphology Saturation binding and Scatchard analyses using radiolabelled fibronectin revealed a concurrent down-modulation of cell-surface fibronectin binding sites, but the binding affinity of the receptor for the ligand was not affected. Immunoblotting and immunostaining revealed down-modulation of the expression of α5β1 integrins. Expression of antisense fibronectin RNA in AKR-MCA cells down-modulated the ability of DMF to restore normal fibronectin production, cell-surface fibronectin binding receptor, adhesion to extracellular fibronectin, and cellular morphology. These studies show that both fibronectin and its cell-surface fibronectin binding receptor were tightly regulated during transformation and induction of differentiation in these cells, that the ligand and its cell-surface fibronectin binding receptor worked together to bring about phenotypic changes, and that fibronectin production regulated the expression of its cell-surface fibronectin binding receptor. © 1994 Wiley-Liss, Inc.

Additional Material: 12 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041610310

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Role of protein kinase C in transforming growth factor-β1 induction of carcinoembryonic antigen in human colon carcinoma cells (1992)

Chakrabarty, Subhas

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 152 (1992), S. 494-499

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Transforming growth factor-β1 (TGF-β1) regulates the expression of the carcinoembryonic antigen (CEA) gene family in the human colon carcinoma cell line Moser. The mechanisms through which it acts, however, are unknown. In this communication, several lines of evidence are presented to show that the induction of CEA expression and secretion (collectively called CEA responses) by TGF-β1 is associated with protein kinase C (PKC) pathway of signal transduction. Treatment of intact cells with the PKC-specific inhibitor calphostin C downmodulated cellular PKC phosphotransferase activity and blocked the induction of the CEA responses by TGF-β1. Depletion of PKC by treatment of intact cells with phorbol ester also blocked the action of TGF-β1. The induction of the CEA responses by TGF-β1 was also blocked by the protein kinase inhibitor 1-(isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), which also inhibited cellular PKC activity. However, TGF-β1 did induce the CEA responses in intact cells treated with the calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7), the calmodulin-dependent phosphodiesterase inhibitor calmidazolium, the diacylglycerol kinase inhibitor R59 022, and the G-protein inhibitors cholera toxin and pertussis toxin. Treatment of intact cells with TGF-β1 induced a rapid and transient increase in PKC phosphotransferase activity. TGF-β1, however, was unable to induce PKC enzymatic activity in cells pretreated with calphostin C. Therefore, it is concluded that TGF-β1 regulates the CEA responses through a signal transducing pathway associated with PKC. © 1992 Wiley-Liss, Inc.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041520308

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Role of protein kinase cα in the induction of carcinoembryonic antigen by transforming growth factor β (1995)

Chakrabarty, Subhas ; Huang, Shuang

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 164 (1995), S. 148-153

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Previous studies showed that transforming growth factor b̃ (TGFb̃1) regulates the expression of carcinoembryonic antigen (CEA) and CEA-cross-reactive glycoproteins (CEA-GLYs) in human colon carcinoma cells through a signal-transducing pathway associated with protein kinase C (PKC) (Chakrabarty, J. Cell. Physiol., 1992, 152 494-499). In this study we determined the role of the PKCα isoform in the regulation of CEA and CEA-GLYs expression by TGFb̃1. Expression of PKCα antisense RNA, through transfection experiments with an antisense PKCα expression vector, resulted in down-modulation of PKCα RNA and protein expression. TGFb̃1 was unable to stimulate the expression and secretion of CEA in cells in which the expression of PKCα protein was substantially reduced. The ability of TGFb̃1 to stimulate the expression of the 95- and 55-KDa CEA-GLYs, however, was not affected. We therefore conclude that TGFb̃1 regulates the secretion and expression of CEA through a signal-transducing pathway associated with PKCα. TGFb̃1 may also regulate the expression of CEA-GLYs through signal-transducing pathways associated with other PKC isoforms. © 1995 Wiley-Liss, Inc.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041640119

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