Abstract
The adenomatous polyposis coli protein (APC) is mutated in familial adenomatous polyposis patients as well as in sporadic colorectal tumors. In an attempt to further understand the function of APC, the subcellular localization of APC was examined. Wild-type and mutant forms of APC were expressed in mammalian cells and protein detected by immunofluorescence using monoclonal and polyclonal antibodies. Staining of wild-type APC protein revealed a filamentous network which extended throughout the cytoplasm and colocalized with microtubules. In striking contrast, mutant APC protein gave a diffuse cytoplasmic staining pattern. Treatment with a microtubule depolymerizing agent, nocodazole, caused APC as well as tubulin to become diffusely cytoplasmic. In addition, immunoperoxidaze staining of transfected APC protein followed by transmission electron microscopy revealed staining of microtubules. These results suggest that wild-type but not mutant APC protein may be associated with the microtubule cytoskeleton.
Footnotes
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↵1 This work was supported by NIH Grants GM07184 and CA57345. B. V. is an American Cancer Society Research Professor.
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↵2 To whom requests for reprints should be addressed, at Johns Hopkins Oncology Center, Room 109, 424 North Bond Street, Baltimore, MD 21231.
- Received April 5, 1994.
- Accepted June 1, 1994.
- ©1994 American Association for Cancer Research.
Volume 54, Issue 14
