CellFy: A Cell-Based Fragment Screen against C-Type Lectins

Area of Science:

• Biochemistry
• Drug Discovery
• Cell Biology

Background:

• Fragment-based drug discovery (FBDD) complements high-throughput screening for difficult targets.
• Low-molecular-weight fragments often exhibit low affinity, necessitating sensitive detection methods.
• Conventional screening methods may lack physiological relevance compared to cell-based approaches.

Purpose of the Study:

• To develop a sensitive cell-based fragment screening assay (cellFy) for identifying ligands against challenging targets.
• To apply cellFy to discover fragments targeting C-type lectin receptors (CLRs), specifically Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Nonintegrin (DC-SIGN) and Langerin.
• To establish a multiplexed assay format for simultaneous screening and selectivity counterscreening against multiple CLRs.

Main Methods:

• Development of a cell-based fragment screening assay (cellFy) utilizing a fluorescently labeled multivalent reporter.
• Direct measurement of fragment displacement without enzymatic reactions or receptor activation.
• Application of cellFy to screen fragment libraries against DC-SIGN and Langerin, followed by hit validation.

Main Results:

• Identification of promising fragment candidates for DC-SIGN through cellFy screening.
• Development of a multiplexed assay for simultaneous screening against multiple CLRs, enabling selectivity assessment.
• Demonstration of cellFy's sensitivity and applicability to challenging targets with shallow, hydrophilic binding sites.

Conclusions:

• The cellFy assay provides a sensitive and physiologically relevant platform for fragment-based drug discovery.
• This method is particularly valuable for identifying bioactive fragments against difficult targets like CLRs.
• The developed assay facilitates the rapid discovery of potential immune modulators targeting CLR family receptors.