Fluorophore labeling of a cell-penetrating peptide induces differential effects on its cellular distribution and affects cell viability

TY - JOUR

T1 - Fluorophore labeling of a cell-penetrating peptide induces differential effects on its cellular distribution and affects cell viability

AU - Birch, Ditlev

AU - Christensen, Malene Vinther

AU - Stærk, Dan

AU - Franzyk, Henrik

AU - Nielsen, Hanne Mørck

PY - 2017/12

Y1 - 2017/12

N2 - Cell-penetrating peptides constitute efficient delivery vectors, and studies of their uptake and mechanism of translocation typically involve fluorophore-labeled conjugates. In the present study, the influence of a number of specific fluorophores on the physico-chemical properties and uptake-related characteristics of penetratin were studied. An array of seven fluorophores belonging to distinct structural classes was examined, and the impact of fluorophore labeling on intracellular distribution and cytotoxicity was correlated to the physico-chemical properties of the conjugates. Exposure of several mammalian cell types to fluorophore-penetratin conjugates revealed a strong structure-dependent reduction in viability (1.5- to 20-fold lower IC50 values as compared to those of non-labeled penetratin). Also, the degree of less severe effects on membrane integrity, as well as intracellular distribution patterns differed among the conjugates. Overall, neutral hydrophobic fluorophores or negatively charged fluorophores conferred less cytotoxicity as compared to the effect exerted by positively charged, hydrophobic fluorophores. The latter conjugates, however, exhibited less membrane association and more clearly defined intracellular distribution patterns. Thus, selection of the appropriate flurophore is critical.

AB - Cell-penetrating peptides constitute efficient delivery vectors, and studies of their uptake and mechanism of translocation typically involve fluorophore-labeled conjugates. In the present study, the influence of a number of specific fluorophores on the physico-chemical properties and uptake-related characteristics of penetratin were studied. An array of seven fluorophores belonging to distinct structural classes was examined, and the impact of fluorophore labeling on intracellular distribution and cytotoxicity was correlated to the physico-chemical properties of the conjugates. Exposure of several mammalian cell types to fluorophore-penetratin conjugates revealed a strong structure-dependent reduction in viability (1.5- to 20-fold lower IC50 values as compared to those of non-labeled penetratin). Also, the degree of less severe effects on membrane integrity, as well as intracellular distribution patterns differed among the conjugates. Overall, neutral hydrophobic fluorophores or negatively charged fluorophores conferred less cytotoxicity as compared to the effect exerted by positively charged, hydrophobic fluorophores. The latter conjugates, however, exhibited less membrane association and more clearly defined intracellular distribution patterns. Thus, selection of the appropriate flurophore is critical.

U2 - 10.1016/j.bbamem.2017.09.015

DO - 10.1016/j.bbamem.2017.09.015

M3 - Journal article

C2 - 28919344

SN - 0005-2736

VL - 1859

SP - 2483

EP - 2494

JO - B B A - Biomembranes

JF - B B A - Biomembranes

IS - 12

ER -