Molecular Assembly of Thyroglobulin Induced by In Vitro Nitric Oxide Treatments: Implication Its Role in Thyroid Cells
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The formation of amyloid-like fibrils, which polymerize from various soluble proteins under physiological and acidic conditions, causes a wide range of protein-folding diseases, such as Alzheimer’s disease and Parkinson’s disease. Fibril assembly in in vitro solutions containing nitric oxide, a free radical that functions as an important signalling molecule involved in numerous physiological and pathological processes, has not been reported. Here, we investigated the protein assembly that occur in thyroglobulin under mildly acidic conditions in the presence of nitric oxide. Solution studies, size exclusion chromatography, dynamic light scattering and analytical ultracentrifugation, demonstrated the size changes of thyroglobulin oligomers after nitric oxide treatment. Following electron microscopic analysis visualized their structural changes and revealed that the molecules can morphologically form polymerized fibril assemblies with a length of 2–5 μm and width 10–100 nm. Taken together, these results provide suggestive evidence for the propensity of forming polymerized thyroglobulin fibrils implying their presence in thyroid cells, which may be related to the onset or progression of thyroid diseases.
KeywordsProtein assembly Fibril formation Thyroglobulin Thyroid diseases Oxide-derived reactive species
Reactive oxygen species
Reactive nitrogen species
Nitric oxide synthase
Size exclusion chromatography
Dynamic light scattering
We thank Seong Oak Park for EM imaging. AUC performed at the Central laboratory of Mokpo National University. This work was supported by the Converging Research Center Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (2012K001403) and by Korea Basic Science Institute Grant (T33415).
Conflict of interest
The authors declare no competing financial interests.
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