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Influence of both coculture and BrdU on NOR activity of mouse, rat and human cells
1Institute of Genetics, Academia Sinica, Beijing, China.
Abstract:
The coculture of mouse PG19 cells with human MGC cells can significantly suppress nucleolar organizer region (NORs) activity of both PG19 and MGC cells. 5'-bormodeoxyuridine (BrdU) can also significantly suppress the NOR activity of rat RC cells, human MGC and Hela cells, and mouse PG19 cells: i.e. the average number of Ag-NORs and the number of chromosomes bearing Ag-NORs per cell decrease significantly. The degree of the suppression increases with increase in both BrdU concentration in the culture medium and BrdU treatment time. The suppressed NOR activity of the PG19 cells can gradually be restored when the BrdU-treated cells are transferred into BrdU-free medium for 50 h. In PG19 cells deoxycytidine (dC) can reverse the suppression of NOR activity caused by BrdU. Coculture plus BrdU treatment suppress the NOR activity of PG19 cells more severely than BrdU treatment alone. In coculture medium containing 30 μg BrdU/ml, dC can also reverse the suppression of the NOR activity of PG19 cells but not that of the MGC cells. The degree of the reversion in the coculture plus BrdU treatment is significantly lower than that found with BrdU-treatment alone.
Insights
Bromodeoxyuridine (BrdU) and cell coculture suppress nucleolar organizer region (NOR) activity. BrdU suppression is reversible in mouse cells, but less so in cocultures, especially for human cells.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Nucleolar organizer regions (NORs) are crucial for ribosome biogenesis and are involved in cell proliferation.
- Disruptions in NOR activity are linked to various cellular processes and diseases.
- Understanding factors that modulate NOR activity is important for cell biology research.
Purpose of the Study:
- To investigate the effects of 5'-bromodeoxyuridine (BrdU) and cell coculture on nucleolar organizer region (NOR) activity in different cell lines.
- To determine the reversibility and specificity of BrdU-induced NOR suppression.
Main Methods:
- Coculture of mouse PG19 cells with human MGC cells.
- Treatment of various cell lines (rat RC, human MGC, Hela, mouse PG19) with BrdU at different concentrations and durations.
- Assessment of NOR activity by quantifying silver-stained NORs (Ag-NORs).
- Evaluation of BrdU-induced suppression reversal using deoxycytidine (dC) and BrdU-free medium.
Main Results:
- Coculture of PG19 and MGC cells significantly suppressed NOR activity in both cell types.
- BrdU treatment significantly suppressed NOR activity (average Ag-NORs and chromosomes with Ag-NORs) in rat RC, human MGC, Hela, and mouse PG19 cells.
- NOR suppression increased with higher BrdU concentration and longer treatment time.
- BrdU-induced suppression in PG19 cells was gradually reversible in BrdU-free medium and reversible by dC.
- Combined coculture and BrdU treatment suppressed NOR activity more severely than BrdU alone.
- dC reversed BrdU-induced suppression in PG19 cells within coculture, but not in MGC cells, with lower overall reversion compared to BrdU treatment alone.
Conclusions:
- BrdU and cell coculture are potent suppressors of NOR activity.
- BrdU-induced NOR suppression is cell-type dependent and partially reversible, particularly in mouse cells.
- Coculture conditions can exacerbate BrdU's suppressive effects and alter its reversibility, highlighting complex cellular interactions.
