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Proceedings Paper

Three-dimensional imaging of nucleolin trafficking in normal cells, transfectants, and heterokaryons
Author(s): Byron T. Ballou; Gregory W. Fisher; Jau-Shyong Deng; Thomas R. Hakala; Meera Srivastava; Daniel L. Farkas
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Paper Abstract

The study of intracellular trafficking using labeled molecules has been aided by the development of the cyanine fluorochromes, which are easily coupled, very soluble, resist photobleaching, and fluoresce at far-red wavelengths where background fluorescence is minimal. We have used Cy3-, Cy5-, and Cy5.5-labeled antibodies, antigen-binding fragments, and specifically binding single-stranded oligonucleotides to follow expression and trafficking of nucleolin, the most abundant protein of the nucleolus. Nucleolin shuttles between the nucleolus and the cytoplasm, and is also expressed on the cell surface, allowing us to test our techniques at all three cellular sites. Differentially cyanine-labeled non-specific antibodies were used to control for non-specific binding. Similarly, the differentially labeled non-binding strand of the cloned oligonucleotide served as a control. The multimode microscope allowed us to follow both rapid and slow redistributions of labeled ligands in the same study. We also performed 3-D reconstructions of nucleolin distribution in cells using rapid acquisition and deconvolution. Microinjection of labeled ligands was used to follow intracellular distribution, while incubation of whole cells with antibody and antigen-binding fragments was used to study uptake. To unambiguously define trafficking, and eliminate the possibility of interference by cross-reactive proteins, we transfected mouse renal cell carcinoma cells that express cell surface nucleolin with human nucleolin. We used microinjection and cell surface staining with Cy3- or Cy5- labeled monoclonal antibody D3 (specific for human nucleolin) to assess the cellular distribution of the human protein. Several clones expressed human nucleolin on their surfaces and showed high levels of transport of the human protein into the mouse nucleus and nucleolus. This distribution roughly parallels that of mouse nucleolin as determined by labeled polyclonal antibody. We have used these engineered transfectants to determine whether the cell surface-expressed xenogeneic nucleolin can serve as a target for antibodies in vivo.

Paper Details

Date Published: 1 April 1996
PDF: 8 pages
Proc. SPIE 2680, Ultrasensitive Biochemical Diagnostics, (1 April 1996); doi: 10.1117/12.237600
Show Author Affiliations
Byron T. Ballou, Carnegie Mellon Univ., Univ. of Pittsburgh School of Medicine, and VA Medical Ctr. (United States)
Gregory W. Fisher, Carnegie Mellon Univ. (United States)
Jau-Shyong Deng, Univ. of Pittsburgh School of Medicine and VA Medical Ctr. (United States)
Thomas R. Hakala, Univ. of Pittsburgh School of Medicine and VA Medical Ctr. (United States)
Meera Srivastava, National Institutes of Health (United States)
Daniel L. Farkas, Carnegie Mellon Univ. (United States)

Published in SPIE Proceedings Vol. 2680:
Ultrasensitive Biochemical Diagnostics
Gerald E. Cohn; Steven A. Soper; C. H. Winston Chen, Editor(s)

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