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The lectin-binding pattern of nucleolin and its interaction with endogenous galectin-3
Dorota Hoja-Łukowicz1, Sylwia Kedracka-Krok, Weronika Duda
1Department of Glycoconjugate Biochemistry, Institute of Zoology, Jagiellonian University, 9 Gronostajowa Street, 30-387, Kraków, Poland, dorota.hoja-lukowicz@uj.edu.pl.
Cellular & Molecular Biology Letters
|August 30, 2014
Summary
Surface and cytoplasmic nucleolin display distinct glycosylation and proteolysis patterns. Nucleolin and galectin-3 form complexes in melanoma cells, suggesting galectin-3 roles in DNA organization and ribosome biogenesis.
Area of Science:
- Biochemistry
- Cell Biology
- Glycobiology
Background:
- Nucleolin is a multifunctional protein found in the nucleus, cytoplasm, and on the cell surface.
- Previous studies indicated differences in nucleolin's localization and function, but its post-translational modifications and interactions in different cellular compartments were not fully understood.
Purpose of the Study:
- To investigate the localization-dependent differences in glycosylation and proteolysis of nucleolin.
- To explore the interaction between nucleolin and galectin-3 in various cellular compartments of melanoma cells.
Main Methods:
- Immunofluorescence microscopy to assess nucleolin localization and glycosylation.
- Western blotting and mass spectrometry to analyze nucleolin proteolysis patterns.
- Co-immunoprecipitation assays to detect nucleolin-galectin-3 complex formation.
Main Results:
- Surface-expressed and cytoplasmic nucleolin exhibit Tn antigen, unlike nuclear nucleolin.
- Distinct glycosylation and proteolysis patterns were observed for nucleolin in the nucleus, cytoplasm, and on the cell surface.
- Full-length nucleolin and proteolytic fragments coexist in live cells.
- Extranuclear nucleolin undergoes N- and O-glycosylation; membrane-associated nucleolin is not fucosylated.
- Nucleolin and galectin-3 form complexes in the nucleolus, cytoplasm, and on the cell surface of melanoma cells.
- Nucleolar co-localization of nucleolin and galectin-3 suggests galectin-3's involvement in DNA organization and ribosome biogenesis.
Conclusions:
- Nucleolin exhibits differential post-translational modifications and proteolysis based on its cellular localization.
- Galectin-3 interacts with nucleolin in multiple cellular compartments, including the nucleolus, cytoplasm, and cell surface.
- These findings suggest novel roles for galectin-3 in nucleolar functions such as DNA organization and ribosome biogenesis.
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