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In vitro and in vivo characterization of pp39mos association with tubulin
R P Zhou1, R L Shen, P Pinto da Silva
1ABL-Basic Research Program, NCI-Frederick Cancer Research & Development Center, Maryland 21702.
Abstract:
The product of protooncogene c-mos, pp39mos, is expressed and functions during oocyte maturation. We have previously found that pp39mos is complexed with and phosphorylates tubulin. In addition, part of pp39mos is localized on mitotic spindle and spindle pole regions in c-mosxe-transformed NIH/3T3 cells. Here, we further characterized the interaction between pp39mos and tubulin. We show that mos product synthesized in vitro appears in a 500 kD complex and can oligomerize with tubulin in vitro under tubulin polymerization conditions. Moreover, conditions which favor microtubule depolymerization facilitate pp39mos extraction from c-mosxe-transformed NIH/3T3 cells. We also show by immunofluorescence and immunoelectron microscopy that pp39mos is localized on microtubules. Thus, in vitro and in vivo the mos product is associated with tubulin and microtubules, respectively. Therefore, the mos product may be involved in the modification of microtubules and formation of the spindle.
Insights
The mos product (pp39mos) interacts with tubulin and microtubules. This suggests a role for the mos product in microtubule modification and spindle formation during cell division.
Area of Science:
- Cell Biology
- Molecular Biology
- Oncology
Background:
- Protooncogene c-mos product, pp39mos, is crucial for oocyte maturation.
- Previous studies indicated pp39mos complexes with and phosphorylates tubulin.
- pp39mos has been observed in mitotic spindle regions of transformed cells.
Purpose of the Study:
- To further characterize the interaction between pp39mos and tubulin.
- To investigate the association of pp39mos with microtubules in vitro and in vivo.
Main Methods:
- In vitro synthesis and oligomerization of mos product with tubulin.
- Microtubule depolymerization and protein extraction experiments.
- Immunofluorescence and immunoelectron microscopy for localization studies.
Main Results:
- Synthesized mos product forms a 500 kD complex with tubulin in vitro.
- Microtubule depolymerization conditions enhance pp39mos extraction from cells.
- Immunolocalization confirms pp39mos association with microtubules.
Conclusions:
- The mos product (pp39mos) directly associates with tubulin and microtubules.
- pp39mos may play a role in microtubule dynamics and spindle assembly.
- Findings suggest a novel function for the mos product in cell division processes.