Truncated peptides from melittin and its analog with high lytic activity at endosomal pH enhance branched polyethylenimine-mediated gene transfection.
BACKGROUND
Melittin is a commonly used cell-penetrating peptide (CPP) for improving branched polyethylenimine (BPEI)-mediated gene transfection. However, its application is limited owing to the cytotoxicity generated by the lytic activity at neutral pH. In the present study, we report two truncated peptides from melittin and florae with improved transfection efficiency.


METHODS
Two truncated peptides consisting of 1-20 residues of melittin (MT20) and florae (FL20) were synthesized. Circular dichroism (CD) spectrometry was used to analyze the secondary structures of the peptides. The membrane-lytic activity of the peptides and their potency in enhancing cellular uptake of calcein were evaluated. The peptides and BPEI mixtures were mixed with plasmid DNA to prepare peptide/BPEI/DNA complexes. The physicochemical characters of complexes were measured and the effect of the peptides on BPEI-mediated transfection was determined.


RESULTS
CD analysis and structure observation showed that the truncated peptides have α-helical conformation, which was necessary for penetrating activity. The truncated peptides exhibited several advantages than their parent peptides: (i) they showed higher hemolytic potency in acidic pH but lower lytic activity than their parent peptides in neutral pH; (ii) enhanced calcein efficiently release from both early and late endosome; (iii) they did not affect the DNA-binding affinity of BPEI and the physicochemical characteristics of BPEI/DNA complexes. Moreover, the peptides could increase BPEI-mediated transfection efficiency in different cell lines (293FT, B16F10 and CHO-K1) by simply mixing with BPEI, without causing cytotoxicity.


CONCLUSIONS
The results obtained in the present study indicate that the truncated peptides with higher endosomal disrupting activity were better enhancers for increasing transfection efficiency.
Beijing Institute of Transfusion Medicine, Beijing, People's Republic of China.
Ying-Xia
YX
Tan
Chong
C
Chen
Ying-Li
YL
Wang
Song
S
Lin
Yang
Y
Wang
Su-Bo
SB
Li
Xiao-Pan
XP
Jin
Hong-Wei
HW
Gao
Fu-Sheng
FS
Du
Feng
F
Gong
Shou-Ping
SP
Ji
D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D057846:Cell-Penetrating Peptides / Q000737:chemistry*; D002942:Circular Dichroism; D006224:Cricetinae; D004247:DNA / Q000008:administration & dosage; D004337:Drug Carriers; D011992:Endosomes / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008555:Melitten / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D014162:Transfection / Q000379:methods*
D057846:Cell-Penetrating Peptides; D004337:Drug Carriers; D008555:Melitten; D011094:Polyethyleneimine; D004247:DNA