Identification of tumor promoters by their inhibitory effect on intercellular transfer of lucifer yellow

1989 ◽  
Vol 5 (1) ◽  
pp. 77-89 ◽  
Author(s):  
Irene V. Budunova ◽  
Leonid A. Mittelman ◽  
Gennady A. Belitsky
Keyword(s):  
Lucifer Yellow ◽  
Inhibitory Effect ◽  
Tumor Promoters ◽  
Intercellular Transfer

The effect of complete carcinogens on intercellular transfer of lucifer yellow in fibroblast culture

1990 ◽  
Vol 6 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Irene V. Budunova ◽  
Leonid A. Mittelman ◽  
Gennady A. Belitsky
Keyword(s):  
Lucifer Yellow ◽  
Fibroblast Culture ◽  
Intercellular Transfer ◽  
Complete Carcinogens

A Swiss 3T3 variant cell line resistant to the effects of tumor promoters cannot be transformed by src

1990 ◽  
Vol 10 (8) ◽  
pp. 4155-4162
Author(s):  
M Nori ◽  
L K Shawver ◽  
M J Weber
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Line ◽  
Inhibitory Effect ◽  
Tumor Promoters ◽  
Kinase C ◽  
Growth Inhibitory ◽  
Variant Cell ◽  
Swiss 3T3 ◽  
Variant Cell Line

To study the relationship between oncogenesis by v-src and normal cellular signalling pathways, we determined the effects of v-src on 3T3-TNR9 cells, a Swiss 3T3 variant which does not respond mitogenically to tumor promoters such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We found that src was unable to transform these variant cells, whether the oncogene was introduced by infection with a murine retrovirus vector or by transfection with plasmid DNA. 3T3-TNR9 cells were not inherently resistant to transformation, since infection with similar recombinant retroviruses containing either v-ras or v-abl did induce transformation. Further analysis of Swiss 3T3 and 3T3-TNR9 cell populations infected with the v-src-containing retrovirus revealed that although the amount of v-src DNA in each was approximately the same, the level of the v-src message and protein and the overall level of phosphotyrosine expressed in the infected variants was much less than in infected parental cells. Cotransfection experiments using separate v-src and neo plasmids revealed a decrease in the number of G418-resistant colonies when transfections of TNR9 cells occurred in the presence of the src-containing plasmid, suggesting a growth inhibitory effect of v-src on 3T3-TNR9 cells, as has also been found for TPA itself. Since v-src cannot transform this variant cell line, which does not respond mitogenically to the protein kinase C agonist TPA, we suggest that src makes use of the protein kinase C pathway as part of its signalling activities.

Transport of the cationic fluorochrome rhodamine 123 in an insect's Malpighian tubule: indications of a reabsorptive function of the secondary cell type

1992 ◽  
Vol 101 (2) ◽  
pp. 349-361
Author(s):  
W. Meulemans ◽  
A. De Loof
Keyword(s):  
Lucifer Yellow ◽  
Malpighian Tubule ◽  
Inhibitory Effect ◽  
Malpighian Tubules ◽  
Rhodamine 123 ◽  
Primary Cells ◽  
Short Period ◽  
Selective Accumulation

The pathway of rhodamine 123 was examined after injection into Sarcophaga flies and after in vitro labeling of the Malpighian tubules. After in vitro labeling the primary cells only retained this potential-sensitive dye for a short period while all secondary cells accumulated the dye from the tubule lumen. In vivo the secondary cells also accumulated rhodamine 123 from the lumen, but the primary cells in the distal parts of all four tubules retained the dye for prolonged periods. This was most pronounced in the distal part of the anterior Malpighian tubules, where rhodamine 123 was eventually precipitated on the luminal concretions. Rhodamine 123 initially accumulated in the secondary cell mitochondria and eventually in intensely fluorescing vesicles, probably lysosomes. No evidence for endocytotic processes from the lumen was found using Lucifer Yellow CH, fluorescent dextrans and fluorescent albumin. Prior incubation with the ionophores valinomycin, nigericin, CCCP (all 1 micrograms/ml), dinitrophenol (1 mM) and NaN3 (10(−2) M) inhibited the selective accumulation of rhodamine 123 to a large extent while monensin (1–5 micrograms/ml) showed little inhibitory effect. Furthermore, only cationic and no anionic or neutral dyes were accumulated by the secondary cells. In the fleshfly Calliphora and the fruitfly Drosophila, the dye rhodamine 123 also selectively accumulated in the secondary cells, as well in vitro as in vivo.

scholarly journals Transfected connexin45 alters gap junction permeability in cells expressing endogenous connexin43.

1995 ◽  
Vol 130 (4) ◽  
pp. 987-995 ◽  
Author(s):  
M Koval ◽  
S T Geist ◽  
E M Westphale ◽  
A E Kemendy ◽  
R Civitelli ◽  
...  
Keyword(s):  
Gap Junction ◽  
Lucifer Yellow ◽  
Direct Interaction ◽  
Full Length ◽  
Osteosarcoma Cell ◽  
Dye Transfer ◽  
Fluorescent Reporter ◽  
Intercellular Transfer ◽  
Carboxyl Terminal ◽  
Gap Junctional

Many cells express multiple connexins, the gap junction proteins that interconnect the cytosol of adjacent cells. Connexin43 (Cx43) channels allow intercellular transfer of Lucifer Yellow (LY, MW = 443 D), while connexin45 (Cx45) channels do not. We transfected full-length or truncated chicken Cx45 into a rat osteosarcoma cell line ROS-17/2.8, which expresses endogenous Cx43. Both forms of Cx45 were expressed at high levels and colocalized with Cx43 at plasma membrane junctions. Cells transfected with full-length Cx45 (ROS/Cx45) and cells transfected with Cx45 missing the 37 carboxyl-terminal amino acids (ROS/Cx45tr) showed 30-60% of the gap junctional conductance exhibited by ROS cells. Intercellular transfer of three negatively charged fluorescent reporter molecules was examined. In ROS cells, microinjected LY was transferred to an average of 11.2 cells/injected cell, while dye transfer between ROS/Cx45 cells was reduced to 3.9 transfer between ROS/Cx45 cells was reduced to 3.9 cells. In contrast, ROS/Cx45tr cells transferred LY to > 20 cells. Transfer of calcein (MW = 623 D) was also reduced by approximately 50% in ROS/Cx45 cells, but passage of hydroxycoumarin carboxylic acid (HCCA; MW = 206 D) was only reduced by 35% as compared to ROS cells. Thus, introduction of Cx45 altered intercellular coupling between cells expressing Cx43, most likely the result of direct interaction between Cx43 and Cx45. Transfection of Cx45tr and Cx45 had different effects in ROS cells, consistent with a role of the carboxyl-terminal domain of Cx45 in determining gap junction permeability or interactions between connexins. These data suggest that coexpression of multiple connexins may enable cells to achieve forms of intercellular communication that cannot be attained by expression of a single connexin.

Voltage-Dependent Calcium Currents in Bulbospinal Neurons of Neonatal Rat Rostral Ventrolateral Medulla: Modulation by α2-Adrenergic Receptors

1998 ◽  
Vol 79 (2) ◽  
pp. 583-594 ◽  
Author(s):  
Yu-Wen Li ◽  
Patrice G. Guyenet ◽  
Douglas A. Bayliss
Keyword(s):  
Adrenergic Receptors ◽  
Calcium Current ◽  
Low Voltage ◽  
Lucifer Yellow ◽  
Inhibitory Effect ◽  
Rostral Ventrolateral Medulla ◽  
Calcium Currents ◽  
Neonatal Rat ◽  
Ventrolateral Medulla ◽  
Voltage Dependent

Li, Yu-Wen, Patrice G. Guyenet, and Douglas A. Bayliss. Voltage-dependent calcium currents in bulbospinal neurons of neonatal rat rostral ventrolateral medulla: modulation by α2-adrenergic receptors. J. Neurophysiol. 79: 583–594, 1998. The properties and modulation by norepinephrine (NE) of voltage-dependent calcium currents were studied in bulbospinal neurons ( n = 116) of the rostral ventrolateral medulla (RVLM) using whole cell patch-clamp techniques in neonatal rat brain stem slices. RVLM bulbospinal neurons were identified visually by their location in slices and by the presence of flourescein isothiocyanate-tagged microbeads, which were injected into the spinal cord before the experiment; RVLM neurons were filled with Lucifer yellow during recordings, and the slice was processed for detection of tyrosine hydroxylase immunoreactivity (TH-IR). Thirty-four of 42 recovered cells (81%) were positive for TH-IR, indicating that most recorded cells were C1 neurons. Bulbospinal RVLM neurons expressed a prominent high-voltage–activated (HVA) calcium current, which began to activate at −30 to −40 mV (from a holding potential of −60 or −70 mV), and peaked at ∼0 mV (0.8 ± 0.1 nA;mean ± SE). HVA current comprised predominantly ω-conotoxin GVIA-sensitive, N-type and ω-agatoxin IVA-sensitive, P/Q-type components, with smaller dihydropyridine-sensitive, L-type, and residual current components. Most RVLM bulbospinal neurons ( n = 44/52, including 12/14 histologically identified C1 cells) also expressed low-voltage–activated (LVA) calcium current. LVA current began to activate at ∼−60 mV (from a holding potential of −100 mV) and was nearly completely inactivated at −50 mV with a half-inactivation potential of −70 ± 2 mV. The amplitude of LVA current at −50 mV was 78 ± 24 pA with Ba2+ and 156 ± 38 pA with Ca2+ as a charge carrier. NE inhibited HVA current in most bulbospinal RVLM neurons ( n = 70/77) with an EC50 of 1.2 μM; NE had no effect on LVA current. Calcium current inhibition by NE was mediated by α2-adrenergic receptors (α2-ARs) as the effect was mimicked by the selective α2-AR agonist, UK-14,304, and blocked by idazoxan, an α2-AR antagonist, but unaffected by prazosin and propranolol (α1- and β-AR antagonists, respectively). Most of the NE-sensitive calcium current was N- and P/Q-type. NE-induced inhibition of calcium current evoked by action potential waveforms (APWs) was significantly larger than that evoked by depolarizing steps (34 ± 2.5 vs. 23 ± 2.7%; P < 0.05). Although inhibition of calcium current was voltage dependent and partially relieved by strong depolarizations, when calcium currents were evoked with a 10-Hz train of APWs as a voltage command, the inhibitory effect of NE was maintained throughout the train. In conclusion, bulbospinal RVLM neurons, including C1 cells, express multiple types of calcium currents. Inhibition of HVA calcium current by NE may modulate input-output relationships and release of transmitters from C1 cells.

scholarly journals A Swiss 3T3 variant cell line resistant to the effects of tumor promoters cannot be transformed by src.

1990 ◽  
Vol 10 (8) ◽  
pp. 4155-4162 ◽  
Author(s):  
M Nori ◽  
L K Shawver ◽  
M J Weber
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Line ◽  
Inhibitory Effect ◽  
Tumor Promoters ◽  
Kinase C ◽  
Growth Inhibitory ◽  
Variant Cell ◽  
Swiss 3T3 ◽  
Variant Cell Line

To study the relationship between oncogenesis by v-src and normal cellular signalling pathways, we determined the effects of v-src on 3T3-TNR9 cells, a Swiss 3T3 variant which does not respond mitogenically to tumor promoters such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We found that src was unable to transform these variant cells, whether the oncogene was introduced by infection with a murine retrovirus vector or by transfection with plasmid DNA. 3T3-TNR9 cells were not inherently resistant to transformation, since infection with similar recombinant retroviruses containing either v-ras or v-abl did induce transformation. Further analysis of Swiss 3T3 and 3T3-TNR9 cell populations infected with the v-src-containing retrovirus revealed that although the amount of v-src DNA in each was approximately the same, the level of the v-src message and protein and the overall level of phosphotyrosine expressed in the infected variants was much less than in infected parental cells. Cotransfection experiments using separate v-src and neo plasmids revealed a decrease in the number of G418-resistant colonies when transfections of TNR9 cells occurred in the presence of the src-containing plasmid, suggesting a growth inhibitory effect of v-src on 3T3-TNR9 cells, as has also been found for TPA itself. Since v-src cannot transform this variant cell line, which does not respond mitogenically to the protein kinase C agonist TPA, we suggest that src makes use of the protein kinase C pathway as part of its signalling activities.

Inhibitory effect of iridoids on Epstein-Barr virus activation by a short-term in vitro assay for anti-tumor promoters

1996 ◽  
Vol 102 (1-2) ◽  
pp. 223-226 ◽  
Author(s):  
Govind J. Kapadia ◽  
Shekhar C. Sharma ◽  
Harukuni Tokuda ◽  
Hoyoku Nishino ◽  
Shinichi Ueda
Keyword(s):  
Epstein Barr Virus ◽  
Inhibitory Effect ◽  
In Vitro Assay ◽  
Tumor Promoters ◽  
Short Term ◽  
Vitro Assay ◽  
Barr Virus ◽  
Epstein Barr
Sign in / Sign up

Export Citation Format

Share Document