Bioorthogonal probes for imaging sterols in cells

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• Cholesterol is a vital lipid in eukaryotic cell membranes and a precursor for signaling molecules like oxysterols and steroid hormones.
• Sterols, including cholesterol and oxysterols, are crucial for Hedgehog signaling, impacting embryogenesis and cancer.
• Current methods for imaging sterols within cells are limited, hindering research into their diverse biological roles.

Purpose of the Study:

• To develop a novel and adaptable microscopy technique for visualizing sterols in living cells.
• To create functional alkyne-modified cholesterol and oxysterol analogues for cellular imaging.
• To demonstrate the utility of these probes in studying sterol distribution and function in cellular processes.

Main Methods:

• Synthesis of C19 alkyne cholesterol and oxysterol analogues that are biologically active.
• Incorporation of alkyne sterol analogues into cellular membranes.
• High-resolution imaging via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) with fluorescent azides.

Main Results:

• Alkyne sterol analogues were found to be fully functional, supporting growth in cholesterol-auxotrophic cells.
• These analogues effectively mimicked the roles of native sterols in Hedgehog signal transduction.
• The method enabled high-resolution visualization of subcellular sterol distribution and dual-labeling with phospholipids.

Conclusions:

• A robust and versatile sterol microscopy method using alkyne analogues has been established.
• This imaging strategy allows for detailed study of sterol localization and function within cells.
• The technique holds broad applicability for investigating the roles of sterols in physiology and disease states.