Aptamer-recognized carbohydrates on the cell membrane revealed by super-resolution microscopy

Area of Science:

• Biochemistry and Molecular Biology
• Cell Biology
• Biotechnology

Background:

• Cell membrane carbohydrates play crucial roles in physiological processes, and their altered expression indicates disease.
• Traditional carbohydrate analysis often uses lectins, but their multivalent nature and crosslinking artifacts limit precise structural visualization.
• Aptamers, small and flexible molecules, present a novel alternative for high-resolution carbohydrate imaging.

Purpose of the Study:

• To develop and validate an aptamer-based method for high-precision imaging of membrane-bound N-acetylgalactosamine (GalNAc).
• To compare the resolution and specificity of aptamer recognition against lectin recognition for GalNAc visualization.
• To assess the potential of aptamers as substitutes for lectins in super-resolution fluorescence imaging of carbohydrates.

Main Methods:

• Development of an aptamer recognition assay for imaging membrane-bound GalNAc.
• Utilizing direct stochastic optical reconstruction microscopy (dSTORM) for nanometer-scale visualization.
• Comparative analysis of aptamer versus lectin recognition methods using N-acetylgalactosidase treatment.

Main Results:

• Aptamer recognition achieved high-resolution imaging of GalNAc clusters on the cell membrane (23 ± 7 nm).
• GalNAc was observed to form irregular clusters on the cell membrane.
• Aptamer-based GalNAc imaging demonstrated significantly greater reduction in cluster size and density after enzyme treatment compared to lectin methods, confirming superior specificity.

Conclusions:

• Aptamers provide a highly precise and specific alternative to lectins for carbohydrate labeling.
• The aptamer recognition method enables detailed nanometer-scale visualization of membrane-bound carbohydrates.
• This approach holds significant potential for advancing super-resolution fluorescence imaging in glycobiology and diagnostics.