Submitted on November 8, 2005
Revised on December 19, 2005
Accepted on December 19, 2005
Synthesis and biological properties of the fluorescent ether lipid precursor, 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol
Hongying Zheng, Richard I. Duclos . Jr, Conor C. Smith, Harrison W. Farber, and Raphael A. Zoeller
Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
Corresponding Author: rzoeller{at}bu.edu
The synthesis of an -pyrene-labeled 1-O-alkyl-sn-glycerol was performed using a chirospecific method starting from R-(-)-2,3-O-isopropylidene-sn-glycerol. The product, 1-O-[9'-(1"-pyrenyl)]nonyl-sn-glycerol (pAG) is a fluorescent ether lipid that has a pyrene moiety covalently attached at the alkyl chain terminus. pAG was taken up into CHO-K1 cells and a plasmalogen-deficient variant of CHO-K1, NRel-4. This variant is defective in dihydroxyacetonephosphate acyltransferase, which catalyzes the first step in plasmenylethanolamine biosynthesis. pAG was incorporated primarily into ethanolamine and choline phospholipids as well as a neutral lipid fraction tentatively identified as alkyldiacylglycerols. NRel-4 accumulated more fluorescence in the phospholipid fraction than CHO-K1, specifically in the ethanolamine phospholipids. Analysis of the fluorescent lipids showed that 93% of the pAG was incorporated into glycerolipids with the ether bond intact. While the addition of 20 µM 1-O-hexadecyl-sn-glycerol (HG) to the medium fully restored plasmenylethanolamine biosynthesis in NRel-4 cells, pAG only partially restored plasmenylethanolamine synthesis. Incubation of cells with pAG followed by irradiation with long wavelength (>300 nm) ultraviolet light resulted in cytotoxicity. NRel-4 cells displayed an increased sensitivity to this treatment when compared with CHO-K1 cells. This photodynamic cytotoxicity approach could be employed to select for mutants which are defective in downstream steps in ether lipid biosynthesis.