UC San Diego

Guanidinium-rich molecular transporters have been shown to deliver otherwise non-permeable biologically relevant cargo into cells. While many such transporters have been reported, the studies reported here focus on guanidinoglycosides, which have been shown to permeate the cell-membrane in a heparan sulfate-dependent manner. In attempt to promote a cooperative interaction with cell- surface heparan sulfate, dimeric guanidinoglycosides were synthesized and studied for their cellular uptake properties in various Chinese hamster ovary (CHO) cell lines. Flow cytometry studies revealed that conjugates prepared with the monomeric compounds showed reduced uptake in mutant cells expressing heparan sulfate chains with altered patterns of sulfation, whereas the dimeric constructs could distinguish the various mutants and maintain high levels of uptake. These findings suggest that uptake depends on the valency of the transporter and the sulfate content on the cell surface receptors, thereby providing reagents that could distinguish cell types based on the composition of their cell surface heparan sulfate proteoglycans. To further investigate the viability of these transporters, their potential to escape endosomal vesicles and diffuse into the cytosol was examined using a FRET-based cellular assay in HeLa cells. Findings indicate that guanidinoglycosides appear to enter the cytosol at around half the rate of poly9arginine. Interestingly, confocal microscopy studies indicate co-localization of the two different transporters