Glycosylation modifications are a typical class of modifications that arise on exosomal membrane proteins and membrane lipids, which play a critical role in exosome-mediated cell differentiation, pathogen invasion, and the biological phenomena of tumorigenesis, development, and migration. Creative Biolabs offers a service to detect glycosylated exosomes with lectin microarrays, allowing for high-throughput resolution of specific glycan structures in exosomes.

Rationale of Lectin Microarray Detection

Lectins is a group of naturally occurring glycan-binding proteins with more than one site that recognizes and binds specific glycan structures, linking different cells that contribute to cell recognition and adhesion reactions. This capability of lectins allows the development of strategies to identify glycoprotein modifications and glycan structures on exosomes. The lectin microarray technology is designed to immobilize multiple classical lectins in the form of microarrays on the polymeric 3D chip substrates to form high-throughput lectin microarrays. This has resulted in a shift from "one-to-one" to "many-to-many" studies for glycan structure resolution and allows simultaneous screening and cross-validation of multiple glycan structures. The lectin microarray provides a beneficial tool for researchers focused on the analysis of exosomal protein glycosylation.

Fig.1 Schematic protocol of glycoprotein analysis using lectin-based microarray system. (Hatakeyama, 2021)

High-Throughput Exosomal Lectin Chip Detection Service at Creative Biolabs

At Creative Biolabs, glycan structure profiling based on lectin microarray technology has been developed for multi-directional glycan profiling, including specific protein surface glycan profile construction and differential detection, live cell surface glycan profile construction and differential detection, cell/tissue lysate glycan profile construction and differential detection, clinical sample glycan profile construction and biomarker discovery, and coupling with mass spectrometry technology to study glycosylated proteome. More complex research projects can be accomplished by the combination of high-throughput lectin microarray and exosomal glycosylated proteome mass spectrometry. We assist in the differential screening of glycoprotein profiles in high-volume exosome samples by high-throughput lectin microarrays to discover candidate markers. The exosomal glycoproteins identified by specific lectins are then resolved with glycosylated proteomic mass spectra to obtain a complete structure of the exosomal glycoprotein profile and glycosylation site map. Our lectin microarrays feature the following,

• Specifications: crystal-core polymer 3D substrate, size 75x25 mm.
• Lectin types: 55 types.
• Dot volume: 0.5~1 nL/dot.
• Dot diameter: ~120 microns.
• Dot spacing: 270 µm in the X-direction and 300 µm in the Y-direction (circular spacing).
• Technical repetition: 3 repetitive dots on each chip.
• Chip dot post-processing: 4 °C overnight fixation followed by long-term storage at -80 °C.

Fig.2 High-throughput exosomal lectin chip detection workflow.

Application

The application of lectin microarrays to biomarker development protocols, which integrate protein microarrays and mass spectrometry, provides new research ideas for marker development in a variety of complex diseases. For example, breast cancer is accompanied by a significant decrease in bisecting GlcNAc modifications, while exosomal membrane proteins secreted by more aggressive cancer cells also lowly express bisecting GlcNAc modifications. The altered glycoproteins on the surface of exosome-treated breast cancer cells were analyzed with a specific lectin enrichment combined with mass spectrometry strategy, from which it was found that integrin β1 may be regulated by bisecting GlcNAc modification. Further glycosylated proteome mass spectrometry analysis resolved the glycan structure of GlcNAc modification and confirmed its ability to bind to integrin β1 and the binding site. Finally, blocking experiments confirmed that the modification of bisecting GlcNAc on exosomes and their cells deregulated the extension of glycan chains, leading to the activation of the recipient cell membrane protein integrin β1 and its downstream FAK-AKT pathway. Thus allowing such exosomes to mediate the ability of recipient cells to become cancerous and accelerate metastasis. This started with exosomes and their cellular low expression of glycoconjugates, deciphering the mechanism of exosomes mediating cancer cell metastasis and identifying relevant glycosylated exosome markers.

Fig.3 Identification of integrin β1 as the target protein bearing bisecting GlcNAc. (Tan, 2020)

Exosomes mediate various physiological processes, including intermolecular recognition, cell adhesion, and tumor metastasis, which involve glycosylation modifications of their exosomal proteins. Creative Biolabs provides high-throughput exosome lectin microarray services to support the development of glycosylation profiles and their associated biomarkers. Please contact us to learn more.

References

1. Hatakeyama, S.; et al. Narrative review of urinary glycan biomarkers in prostate cancer. Transl Androl Urol. 2021, 10(4): 1850-1864.
2. Tan, Z.; et al. Bisecting GlcNAc modification diminishes the pro-metastatic functions of small extracellular vesicles from breast cancer cells. J Extracell Vesicles. 2020, 10(1): e12005.

• Glycosylated Exosomal Proteomic Detection