Synthesis and photochemical properties of PEGylated coumarin-caged ceramides for cell studies

Abstract

Caged ceramide analogues (C6-, C16-, C18-, C22- and C24-Cer) have been prepared by introducing a hydrophilic coumarin-based cage bearing a short polyethylene glycol (PEG) chain. (6-Bromo-7-mTEGylated-coumarin-4-yl)methyl (Btc) caged ceramide showed efficient photo-uncaging to release the parent ceramide upon direct exposure to 350 nm UV light; in contrast (7-mTEGylated-coumarin-4-yl) methyl (Tc) caged ceramide was photolysed more slowly. In preliminary experiments, Btc-caged ceramides were taken up by cells and their photolysis led to decreases in cell viability, but not to activation of caspase enzymes, suggesting that either reactive oxygen species or an alternate caspase-independent pathway may be responsible for the decreases in cell viability caused by photolysis of caged ceramides.

Optical manipulation of sphingolipid biosynthesis using photoswitchable ceramides

“…A distinct advantage of caCers over caged ceramide analogs (Kim et al, 2016; Höglinger et al, 2014; Höglinger et al, 2015) is that their activity can be readily switched off by light. This property enabled us to generate time-resolved pulses of SM synthesis at the plasma membrane of living cells.…”

“…Another method to rapidly increase lipid supply involves the use of caged lipids. These compounds carry a photo-labile protecting group that blocks their biological activity until the active lipid is released with a flash of light (Kim et al, 2016; Höglinger et al, 2014; Höglinger et al, 2015). Alongside the recent development of site-directed variants of caged sphingosine, it has become possible to confine release of this bioactive lipid to specific organelles (Feng et al, 2018).…”